sslutil: config option to specify TLS protocol version

Currently, Mercurial will use TLS 1.0 or newer when connecting to
remote servers, selecting the highest TLS version supported by both
peers. On older Pythons, only TLS 1.0 is available. On newer Pythons,
TLS 1.1 and 1.2 should be available.

Security-minded people may want to not take any risks running
TLS 1.0 (or even TLS 1.1). This patch gives those people a config
option to explicitly control which TLS versions Mercurial should use.
By providing this option, one can require newer TLS versions
before they are formally deprecated by Mercurial/Python/OpenSSL/etc
and lower their security exposure. This option also provides an
easy mechanism to change protocol policies in Mercurial. If there
is a 0-day and TLS 1.0 is completely broken, we can act quickly
without changing much code.

Because setting the minimum TLS protocol is something you'll likely
want to do globally, this patch introduces a global config option under
[hostsecurity] for that purpose.

wrapserversocket() has been taught a hidden config option to define
the explicit protocol to use. This is queried in this function and
not passed as an argument because I don't want to expose this dangerous
option as part of the Python API. There is a risk someone could footgun
themselves. But the config option is a devel option, has a warning
comment, and I doubt most people are using `hg serve` to run a
production HTTPS server (I would have something not Mercurial/Python
handle TLS). If this is problematic, we can go back to using a
custom extension in tests to coerce the server into bad behavior.

mercurial/help/config.txt

@@ -1,2166 +1,2189
 The Mercurial system uses a set of configuration files to control
 aspects of its behavior.
 
 Troubleshooting
 ===============
 
 If you're having problems with your configuration,
 :hg:`config --debug` can help you understand what is introducing
 a setting into your environment.
 
 See :hg:`help config.syntax` and :hg:`help config.files`
 for information about how and where to override things.
 
 Structure
 =========
 
 The configuration files use a simple ini-file format. A configuration
 file consists of sections, led by a ``[section]`` header and followed
 by ``name = value`` entries::
 
   [ui]
   username = Firstname Lastname <[e-mail]>
   verbose = True
 
 The above entries will be referred to as ``ui.username`` and
 ``ui.verbose``, respectively. See :hg:`help config.syntax`.
 
 Files
 =====
 
 Mercurial reads configuration data from several files, if they exist.
 These files do not exist by default and you will have to create the
 appropriate configuration files yourself:
 
 Local configuration is put into the per-repository ``<repo>/.hg/hgrc`` file.
 
 Global configuration like the username setting is typically put into:
 
 .. container:: windows
 
   - ``%USERPROFILE%\mercurial.ini`` (on Windows)
 
 .. container:: unix.plan9
 
   - ``$HOME/.hgrc`` (on Unix, Plan9)
 
 The names of these files depend on the system on which Mercurial is
 installed. ``*.rc`` files from a single directory are read in
 alphabetical order, later ones overriding earlier ones. Where multiple
 paths are given below, settings from earlier paths override later
 ones.
 
 .. container:: verbose.unix
 
   On Unix, the following files are consulted:
 
   - ``<repo>/.hg/hgrc`` (per-repository)
   - ``$HOME/.hgrc`` (per-user)
   - ``<install-root>/etc/mercurial/hgrc`` (per-installation)
   - ``<install-root>/etc/mercurial/hgrc.d/*.rc`` (per-installation)
   - ``/etc/mercurial/hgrc`` (per-system)
   - ``/etc/mercurial/hgrc.d/*.rc`` (per-system)
   - ``<internal>/default.d/*.rc`` (defaults)
 
 .. container:: verbose.windows
 
   On Windows, the following files are consulted:
 
   - ``<repo>/.hg/hgrc`` (per-repository)
   - ``%USERPROFILE%\.hgrc`` (per-user)
   - ``%USERPROFILE%\Mercurial.ini`` (per-user)
   - ``%HOME%\.hgrc`` (per-user)
   - ``%HOME%\Mercurial.ini`` (per-user)
   - ``HKEY_LOCAL_MACHINE\SOFTWARE\Mercurial`` (per-installation)
   - ``<install-dir>\hgrc.d\*.rc`` (per-installation)
   - ``<install-dir>\Mercurial.ini`` (per-installation)
   - ``<internal>/default.d/*.rc`` (defaults)
 
   .. note::
 
    The registry key ``HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Mercurial``
    is used when running 32-bit Python on 64-bit Windows.
 
 .. container:: windows
 
   On Windows 9x, ``%HOME%`` is replaced by ``%APPDATA%``.
 
 .. container:: verbose.plan9
 
   On Plan9, the following files are consulted:
 
   - ``<repo>/.hg/hgrc`` (per-repository)
   - ``$home/lib/hgrc`` (per-user)
   - ``<install-root>/lib/mercurial/hgrc`` (per-installation)
   - ``<install-root>/lib/mercurial/hgrc.d/*.rc`` (per-installation)
   - ``/lib/mercurial/hgrc`` (per-system)
   - ``/lib/mercurial/hgrc.d/*.rc`` (per-system)
   - ``<internal>/default.d/*.rc`` (defaults)
 
 Per-repository configuration options only apply in a
 particular repository. This file is not version-controlled, and
 will not get transferred during a "clone" operation. Options in
 this file override options in all other configuration files.
 
 .. container:: unix.plan9
 
   On Plan 9 and Unix, most of this file will be ignored if it doesn't
   belong to a trusted user or to a trusted group. See
   :hg:`help config.trusted` for more details.
 
 Per-user configuration file(s) are for the user running Mercurial.  Options
 in these files apply to all Mercurial commands executed by this user in any
 directory. Options in these files override per-system and per-installation
 options.
 
 Per-installation configuration files are searched for in the
 directory where Mercurial is installed. ``<install-root>`` is the
 parent directory of the **hg** executable (or symlink) being run.
 
 .. container:: unix.plan9
 
   For example, if installed in ``/shared/tools/bin/hg``, Mercurial
   will look in ``/shared/tools/etc/mercurial/hgrc``. Options in these
   files apply to all Mercurial commands executed by any user in any
   directory.
 
 Per-installation configuration files are for the system on
 which Mercurial is running. Options in these files apply to all
 Mercurial commands executed by any user in any directory. Registry
 keys contain PATH-like strings, every part of which must reference
 a ``Mercurial.ini`` file or be a directory where ``*.rc`` files will
 be read.  Mercurial checks each of these locations in the specified
 order until one or more configuration files are detected.
 
 Per-system configuration files are for the system on which Mercurial
 is running. Options in these files apply to all Mercurial commands
 executed by any user in any directory. Options in these files
 override per-installation options.
 
 Mercurial comes with some default configuration. The default configuration
 files are installed with Mercurial and will be overwritten on upgrades. Default
 configuration files should never be edited by users or administrators but can
 be overridden in other configuration files. So far the directory only contains
 merge tool configuration but packagers can also put other default configuration
 there.
 
 Syntax
 ======
 
 A configuration file consists of sections, led by a ``[section]`` header
 and followed by ``name = value`` entries (sometimes called
 ``configuration keys``)::
 
     [spam]
     eggs=ham
     green=
        eggs
 
 Each line contains one entry. If the lines that follow are indented,
 they are treated as continuations of that entry. Leading whitespace is
 removed from values. Empty lines are skipped. Lines beginning with
 ``#`` or ``;`` are ignored and may be used to provide comments.
 
 Configuration keys can be set multiple times, in which case Mercurial
 will use the value that was configured last. As an example::
 
     [spam]
     eggs=large
     ham=serrano
     eggs=small
 
 This would set the configuration key named ``eggs`` to ``small``.
 
 It is also possible to define a section multiple times. A section can
 be redefined on the same and/or on different configuration files. For
 example::
 
     [foo]
     eggs=large
     ham=serrano
     eggs=small
 
     [bar]
     eggs=ham
     green=
        eggs
 
     [foo]
     ham=prosciutto
     eggs=medium
     bread=toasted
 
 This would set the ``eggs``, ``ham``, and ``bread`` configuration keys
 of the ``foo`` section to ``medium``, ``prosciutto``, and ``toasted``,
 respectively. As you can see there only thing that matters is the last
 value that was set for each of the configuration keys.
 
 If a configuration key is set multiple times in different
 configuration files the final value will depend on the order in which
 the different configuration files are read, with settings from earlier
 paths overriding later ones as described on the ``Files`` section
 above.
 
 A line of the form ``%include file`` will include ``file`` into the
 current configuration file. The inclusion is recursive, which means
 that included files can include other files. Filenames are relative to
 the configuration file in which the ``%include`` directive is found.
 Environment variables and ``~user`` constructs are expanded in
 ``file``. This lets you do something like::
 
   %include ~/.hgrc.d/$HOST.rc
 
 to include a different configuration file on each computer you use.
 
 A line with ``%unset name`` will remove ``name`` from the current
 section, if it has been set previously.
 
 The values are either free-form text strings, lists of text strings,
 or Boolean values. Boolean values can be set to true using any of "1",
 "yes", "true", or "on" and to false using "0", "no", "false", or "off"
 (all case insensitive).
 
 List values are separated by whitespace or comma, except when values are
 placed in double quotation marks::
 
   allow_read = "John Doe, PhD", brian, betty
 
 Quotation marks can be escaped by prefixing them with a backslash. Only
 quotation marks at the beginning of a word is counted as a quotation
 (e.g., ``foo"bar baz`` is the list of ``foo"bar`` and ``baz``).
 
 Sections
 ========
 
 This section describes the different sections that may appear in a
 Mercurial configuration file, the purpose of each section, its possible
 keys, and their possible values.
 
 ``alias``
 ---------
 
 Defines command aliases.
 
 Aliases allow you to define your own commands in terms of other
 commands (or aliases), optionally including arguments. Positional
 arguments in the form of ``$1``, ``$2``, etc. in the alias definition
 are expanded by Mercurial before execution. Positional arguments not
 already used by ``$N`` in the definition are put at the end of the
 command to be executed.
 
 Alias definitions consist of lines of the form::
 
     <alias> = <command> [<argument>]...
 
 For example, this definition::
 
     latest = log --limit 5
 
 creates a new command ``latest`` that shows only the five most recent
 changesets. You can define subsequent aliases using earlier ones::
 
     stable5 = latest -b stable
 
 .. note::
 
    It is possible to create aliases with the same names as
    existing commands, which will then override the original
    definitions. This is almost always a bad idea!
 
 An alias can start with an exclamation point (``!``) to make it a
 shell alias. A shell alias is executed with the shell and will let you
 run arbitrary commands. As an example, ::
 
    echo = !echo $@
 
 will let you do ``hg echo foo`` to have ``foo`` printed in your
 terminal. A better example might be::
 
    purge = !$HG status --no-status --unknown -0 re: | xargs -0 rm
 
 which will make ``hg purge`` delete all unknown files in the
 repository in the same manner as the purge extension.
 
 Positional arguments like ``$1``, ``$2``, etc. in the alias definition
 expand to the command arguments. Unmatched arguments are
 removed. ``$0`` expands to the alias name and ``$@`` expands to all
 arguments separated by a space. ``"$@"`` (with quotes) expands to all
 arguments quoted individually and separated by a space. These expansions
 happen before the command is passed to the shell.
 
 Shell aliases are executed in an environment where ``$HG`` expands to
 the path of the Mercurial that was used to execute the alias. This is
 useful when you want to call further Mercurial commands in a shell
 alias, as was done above for the purge alias. In addition,
 ``$HG_ARGS`` expands to the arguments given to Mercurial. In the ``hg
 echo foo`` call above, ``$HG_ARGS`` would expand to ``echo foo``.
 
 .. note::
 
    Some global configuration options such as ``-R`` are
    processed before shell aliases and will thus not be passed to
    aliases.
 
 
 ``annotate``
 ------------
 
 Settings used when displaying file annotations. All values are
 Booleans and default to False. See :hg:`help config.diff` for
 related options for the diff command.
 
 ``ignorews``
     Ignore white space when comparing lines.
 
 ``ignorewsamount``
     Ignore changes in the amount of white space.
 
 ``ignoreblanklines``
     Ignore changes whose lines are all blank.
 
 
 ``auth``
 --------
 
 Authentication credentials for HTTP authentication. This section
 allows you to store usernames and passwords for use when logging
 *into* HTTP servers. See :hg:`help config.web` if
 you want to configure *who* can login to your HTTP server.
 
 Each line has the following format::
 
     <name>.<argument> = <value>
 
 where ``<name>`` is used to group arguments into authentication
 entries. Example::
 
     foo.prefix = hg.intevation.de/mercurial
     foo.username = foo
     foo.password = bar
     foo.schemes = http https
 
     bar.prefix = secure.example.org
     bar.key = path/to/file.key
     bar.cert = path/to/file.cert
     bar.schemes = https
 
 Supported arguments:
 
 ``prefix``
     Either ``*`` or a URI prefix with or without the scheme part.
     The authentication entry with the longest matching prefix is used
     (where ``*`` matches everything and counts as a match of length
     1). If the prefix doesn't include a scheme, the match is performed
     against the URI with its scheme stripped as well, and the schemes
     argument, q.v., is then subsequently consulted.
 
 ``username``
     Optional. Username to authenticate with. If not given, and the
     remote site requires basic or digest authentication, the user will
     be prompted for it. Environment variables are expanded in the
     username letting you do ``foo.username = $USER``. If the URI
     includes a username, only ``[auth]`` entries with a matching
     username or without a username will be considered.
 
 ``password``
     Optional. Password to authenticate with. If not given, and the
     remote site requires basic or digest authentication, the user
     will be prompted for it.
 
 ``key``
     Optional. PEM encoded client certificate key file. Environment
     variables are expanded in the filename.
 
 ``cert``
     Optional. PEM encoded client certificate chain file. Environment
     variables are expanded in the filename.
 
 ``schemes``
     Optional. Space separated list of URI schemes to use this
     authentication entry with. Only used if the prefix doesn't include
     a scheme. Supported schemes are http and https. They will match
     static-http and static-https respectively, as well.
     (default: https)
 
 If no suitable authentication entry is found, the user is prompted
 for credentials as usual if required by the remote.
 
 
 ``committemplate``
 ------------------
 
 ``changeset``
     String: configuration in this section is used as the template to
     customize the text shown in the editor when committing.
 
 In addition to pre-defined template keywords, commit log specific one
 below can be used for customization:
 
 ``extramsg``
     String: Extra message (typically 'Leave message empty to abort
     commit.'). This may be changed by some commands or extensions.
 
 For example, the template configuration below shows as same text as
 one shown by default::
 
     [committemplate]
     changeset = {desc}\n\n
         HG: Enter commit message.  Lines beginning with 'HG:' are removed.
         HG: {extramsg}
         HG: --
         HG: user: {author}\n{ifeq(p2rev, "-1", "",
        "HG: branch merge\n")
        }HG: branch '{branch}'\n{if(activebookmark,
        "HG: bookmark '{activebookmark}'\n")   }{subrepos %
        "HG: subrepo {subrepo}\n"              }{file_adds %
        "HG: added {file}\n"                   }{file_mods %
        "HG: changed {file}\n"                 }{file_dels %
        "HG: removed {file}\n"                 }{if(files, "",
        "HG: no files changed\n")}
 
 .. note::
 
    For some problematic encodings (see :hg:`help win32mbcs` for
    detail), this customization should be configured carefully, to
    avoid showing broken characters.
 
    For example, if a multibyte character ending with backslash (0x5c) is
    followed by the ASCII character 'n' in the customized template,
    the sequence of backslash and 'n' is treated as line-feed unexpectedly
    (and the multibyte character is broken, too).
 
 Customized template is used for commands below (``--edit`` may be
 required):
 
 - :hg:`backout`
 - :hg:`commit`
 - :hg:`fetch` (for merge commit only)
 - :hg:`graft`
 - :hg:`histedit`
 - :hg:`import`
 - :hg:`qfold`, :hg:`qnew` and :hg:`qrefresh`
 - :hg:`rebase`
 - :hg:`shelve`
 - :hg:`sign`
 - :hg:`tag`
 - :hg:`transplant`
 
 Configuring items below instead of ``changeset`` allows showing
 customized message only for specific actions, or showing different
 messages for each action.
 
 - ``changeset.backout`` for :hg:`backout`
 - ``changeset.commit.amend.merge`` for :hg:`commit --amend` on merges
 - ``changeset.commit.amend.normal`` for :hg:`commit --amend` on other
 - ``changeset.commit.normal.merge`` for :hg:`commit` on merges
 - ``changeset.commit.normal.normal`` for :hg:`commit` on other
 - ``changeset.fetch`` for :hg:`fetch` (impling merge commit)
 - ``changeset.gpg.sign`` for :hg:`sign`
 - ``changeset.graft`` for :hg:`graft`
 - ``changeset.histedit.edit`` for ``edit`` of :hg:`histedit`
 - ``changeset.histedit.fold`` for ``fold`` of :hg:`histedit`
 - ``changeset.histedit.mess`` for ``mess`` of :hg:`histedit`
 - ``changeset.histedit.pick`` for ``pick`` of :hg:`histedit`
 - ``changeset.import.bypass`` for :hg:`import --bypass`
 - ``changeset.import.normal.merge`` for :hg:`import` on merges
 - ``changeset.import.normal.normal`` for :hg:`import` on other
 - ``changeset.mq.qnew`` for :hg:`qnew`
 - ``changeset.mq.qfold`` for :hg:`qfold`
 - ``changeset.mq.qrefresh`` for :hg:`qrefresh`
 - ``changeset.rebase.collapse`` for :hg:`rebase --collapse`
 - ``changeset.rebase.merge`` for :hg:`rebase` on merges
 - ``changeset.rebase.normal`` for :hg:`rebase` on other
 - ``changeset.shelve.shelve`` for :hg:`shelve`
 - ``changeset.tag.add`` for :hg:`tag` without ``--remove``
 - ``changeset.tag.remove`` for :hg:`tag --remove`
 - ``changeset.transplant.merge`` for :hg:`transplant` on merges
 - ``changeset.transplant.normal`` for :hg:`transplant` on other
 
 These dot-separated lists of names are treated as hierarchical ones.
 For example, ``changeset.tag.remove`` customizes the commit message
 only for :hg:`tag --remove`, but ``changeset.tag`` customizes the
 commit message for :hg:`tag` regardless of ``--remove`` option.
 
 When the external editor is invoked for a commit, the corresponding
 dot-separated list of names without the ``changeset.`` prefix
 (e.g. ``commit.normal.normal``) is in the ``HGEDITFORM`` environment
 variable.
 
 In this section, items other than ``changeset`` can be referred from
 others. For example, the configuration to list committed files up
 below can be referred as ``{listupfiles}``::
 
     [committemplate]
     listupfiles = {file_adds %
        "HG: added {file}\n"     }{file_mods %
        "HG: changed {file}\n"   }{file_dels %
        "HG: removed {file}\n"   }{if(files, "",
        "HG: no files changed\n")}
 
 ``decode/encode``
 -----------------
 
 Filters for transforming files on checkout/checkin. This would
 typically be used for newline processing or other
 localization/canonicalization of files.
 
 Filters consist of a filter pattern followed by a filter command.
 Filter patterns are globs by default, rooted at the repository root.
 For example, to match any file ending in ``.txt`` in the root
 directory only, use the pattern ``*.txt``. To match any file ending
 in ``.c`` anywhere in the repository, use the pattern ``**.c``.
 For each file only the first matching filter applies.
 
 The filter command can start with a specifier, either ``pipe:`` or
 ``tempfile:``. If no specifier is given, ``pipe:`` is used by default.
 
 A ``pipe:`` command must accept data on stdin and return the transformed
 data on stdout.
 
 Pipe example::
 
   [encode]
   # uncompress gzip files on checkin to improve delta compression
   # note: not necessarily a good idea, just an example
   *.gz = pipe: gunzip
 
   [decode]
   # recompress gzip files when writing them to the working dir (we
   # can safely omit "pipe:", because it's the default)
   *.gz = gzip
 
 A ``tempfile:`` command is a template. The string ``INFILE`` is replaced
 with the name of a temporary file that contains the data to be
 filtered by the command. The string ``OUTFILE`` is replaced with the name
 of an empty temporary file, where the filtered data must be written by
 the command.
 
 .. container:: windows
 
    .. note::
 
      The tempfile mechanism is recommended for Windows systems,
      where the standard shell I/O redirection operators often have
      strange effects and may corrupt the contents of your files.
 
 This filter mechanism is used internally by the ``eol`` extension to
 translate line ending characters between Windows (CRLF) and Unix (LF)
 format. We suggest you use the ``eol`` extension for convenience.
 
 
 ``defaults``
 ------------
 
 (defaults are deprecated. Don't use them. Use aliases instead.)
 
 Use the ``[defaults]`` section to define command defaults, i.e. the
 default options/arguments to pass to the specified commands.
 
 The following example makes :hg:`log` run in verbose mode, and
 :hg:`status` show only the modified files, by default::
 
   [defaults]
   log = -v
   status = -m
 
 The actual commands, instead of their aliases, must be used when
 defining command defaults. The command defaults will also be applied
 to the aliases of the commands defined.
 
 
 ``diff``
 --------
 
 Settings used when displaying diffs. Everything except for ``unified``
 is a Boolean and defaults to False. See :hg:`help config.annotate`
 for related options for the annotate command.
 
 ``git``
     Use git extended diff format.
 
 ``nobinary``
     Omit git binary patches.
 
 ``nodates``
     Don't include dates in diff headers.
 
 ``noprefix``
     Omit 'a/' and 'b/' prefixes from filenames. Ignored in plain mode.
 
 ``showfunc``
     Show which function each change is in.
 
 ``ignorews``
     Ignore white space when comparing lines.
 
 ``ignorewsamount``
     Ignore changes in the amount of white space.
 
 ``ignoreblanklines``
     Ignore changes whose lines are all blank.
 
 ``unified``
     Number of lines of context to show.
 
 ``email``
 ---------
 
 Settings for extensions that send email messages.
 
 ``from``
     Optional. Email address to use in "From" header and SMTP envelope
     of outgoing messages.
 
 ``to``
     Optional. Comma-separated list of recipients' email addresses.
 
 ``cc``
     Optional. Comma-separated list of carbon copy recipients'
     email addresses.
 
 ``bcc``
     Optional. Comma-separated list of blind carbon copy recipients'
     email addresses.
 
 ``method``
     Optional. Method to use to send email messages. If value is ``smtp``
     (default), use SMTP (see the ``[smtp]`` section for configuration).
     Otherwise, use as name of program to run that acts like sendmail
     (takes ``-f`` option for sender, list of recipients on command line,
     message on stdin). Normally, setting this to ``sendmail`` or
     ``/usr/sbin/sendmail`` is enough to use sendmail to send messages.
 
 ``charsets``
     Optional. Comma-separated list of character sets considered
     convenient for recipients. Addresses, headers, and parts not
     containing patches of outgoing messages will be encoded in the
     first character set to which conversion from local encoding
     (``$HGENCODING``, ``ui.fallbackencoding``) succeeds. If correct
     conversion fails, the text in question is sent as is.
     (default: '')
 
     Order of outgoing email character sets:
 
     1. ``us-ascii``: always first, regardless of settings
     2. ``email.charsets``: in order given by user
     3. ``ui.fallbackencoding``: if not in email.charsets
     4. ``$HGENCODING``: if not in email.charsets
     5. ``utf-8``: always last, regardless of settings
 
 Email example::
 
   [email]
   from = Joseph User <[e-mail]>
   method = /usr/sbin/sendmail
   # charsets for western Europeans
   # us-ascii, utf-8 omitted, as they are tried first and last
   charsets = iso-8859-1, iso-8859-15, windows-1252
 
 
 ``extensions``
 --------------
 
 Mercurial has an extension mechanism for adding new features. To
 enable an extension, create an entry for it in this section.
 
 If you know that the extension is already in Python's search path,
 you can give the name of the module, followed by ``=``, with nothing
 after the ``=``.
 
 Otherwise, give a name that you choose, followed by ``=``, followed by
 the path to the ``.py`` file (including the file name extension) that
 defines the extension.
 
 To explicitly disable an extension that is enabled in an hgrc of
 broader scope, prepend its path with ``!``, as in ``foo = !/ext/path``
 or ``foo = !`` when path is not supplied.
 
 Example for ``~/.hgrc``::
 
   [extensions]
   # (the color extension will get loaded from Mercurial's path)
   color =
   # (this extension will get loaded from the file specified)
   myfeature = ~/.hgext/myfeature.py
 
 
 ``format``
 ----------
 
 ``usegeneraldelta``
     Enable or disable the "generaldelta" repository format which improves
     repository compression by allowing "revlog" to store delta against arbitrary
     revision instead of the previous stored one. This provides significant
     improvement for repositories with branches.
 
     Repositories with this on-disk format require Mercurial version 1.9.
 
     Enabled by default.
 
 ``dotencode``
     Enable or disable the "dotencode" repository format which enhances
     the "fncache" repository format (which has to be enabled to use
     dotencode) to avoid issues with filenames starting with ._ on
     Mac OS X and spaces on Windows.
 
     Repositories with this on-disk format require Mercurial version 1.7.
 
     Enabled by default.
 
 ``usefncache``
     Enable or disable the "fncache" repository format which enhances
     the "store" repository format (which has to be enabled to use
     fncache) to allow longer filenames and avoids using Windows
     reserved names, e.g. "nul".
 
     Repositories with this on-disk format require Mercurial version 1.1.
 
     Enabled by default.
 
 ``usestore``
     Enable or disable the "store" repository format which improves
     compatibility with systems that fold case or otherwise mangle
     filenames. Disabling this option will allow you to store longer filenames
     in some situations at the expense of compatibility.
 
     Repositories with this on-disk format require Mercurial version 0.9.4.
 
     Enabled by default.
 
 ``graph``
 ---------
 
 Web graph view configuration. This section let you change graph
 elements display properties by branches, for instance to make the
 ``default`` branch stand out.
 
 Each line has the following format::
 
     <branch>.<argument> = <value>
 
 where ``<branch>`` is the name of the branch being
 customized. Example::
 
     [graph]
     # 2px width
     default.width = 2
     # red color
     default.color = FF0000
 
 Supported arguments:
 
 ``width``
     Set branch edges width in pixels.
 
 ``color``
     Set branch edges color in hexadecimal RGB notation.
 
 ``hooks``
 ---------
 
 Commands or Python functions that get automatically executed by
 various actions such as starting or finishing a commit. Multiple
 hooks can be run for the same action by appending a suffix to the
 action. Overriding a site-wide hook can be done by changing its
 value or setting it to an empty string.  Hooks can be prioritized
 by adding a prefix of ``priority.`` to the hook name on a new line
 and setting the priority. The default priority is 0.
 
 Example ``.hg/hgrc``::
 
   [hooks]
   # update working directory after adding changesets
   changegroup.update = hg update
   # do not use the site-wide hook
   incoming =
   incoming.email = /my/email/hook
   incoming.autobuild = /my/build/hook
   # force autobuild hook to run before other incoming hooks
   priority.incoming.autobuild = 1
 
 Most hooks are run with environment variables set that give useful
 additional information. For each hook below, the environment
 variables it is passed are listed with names of the form ``$HG_foo``.
 
 ``changegroup``
   Run after a changegroup has been added via push, pull or unbundle.  ID of the
   first new changeset is in ``$HG_NODE`` and last in ``$HG_NODE_LAST``. URL
   from which changes came is in ``$HG_URL``.
 
 ``commit``
   Run after a changeset has been created in the local repository. ID
   of the newly created changeset is in ``$HG_NODE``. Parent changeset
   IDs are in ``$HG_PARENT1`` and ``$HG_PARENT2``.
 
 ``incoming``
   Run after a changeset has been pulled, pushed, or unbundled into
   the local repository. The ID of the newly arrived changeset is in
   ``$HG_NODE``. URL that was source of changes came is in ``$HG_URL``.
 
 ``outgoing``
   Run after sending changes from local repository to another. ID of
   first changeset sent is in ``$HG_NODE``. Source of operation is in
   ``$HG_SOURCE``; Also see :hg:`help config.hooks.preoutgoing` hook.
 
 ``post-<command>``
   Run after successful invocations of the associated command. The
   contents of the command line are passed as ``$HG_ARGS`` and the result
   code in ``$HG_RESULT``. Parsed command line arguments are passed as
   ``$HG_PATS`` and ``$HG_OPTS``. These contain string representations of
   the python data internally passed to <command>. ``$HG_OPTS`` is a
   dictionary of options (with unspecified options set to their defaults).
   ``$HG_PATS`` is a list of arguments. Hook failure is ignored.
 
 ``fail-<command>``
   Run after a failed invocation of an associated command. The contents
   of the command line are passed as ``$HG_ARGS``. Parsed command line
   arguments are passed as ``$HG_PATS`` and ``$HG_OPTS``. These contain
   string representations of the python data internally passed to
   <command>. ``$HG_OPTS`` is a dictionary of options (with unspecified
   options set to their defaults). ``$HG_PATS`` is a list of arguments.
   Hook failure is ignored.
 
 ``pre-<command>``
   Run before executing the associated command. The contents of the
   command line are passed as ``$HG_ARGS``. Parsed command line arguments
   are passed as ``$HG_PATS`` and ``$HG_OPTS``. These contain string
   representations of the data internally passed to <command>. ``$HG_OPTS``
   is a dictionary of options (with unspecified options set to their
   defaults). ``$HG_PATS`` is a list of arguments. If the hook returns
   failure, the command doesn't execute and Mercurial returns the failure
   code.
 
 ``prechangegroup``
   Run before a changegroup is added via push, pull or unbundle. Exit
   status 0 allows the changegroup to proceed. Non-zero status will
   cause the push, pull or unbundle to fail. URL from which changes
   will come is in ``$HG_URL``.
 
 ``precommit``
   Run before starting a local commit. Exit status 0 allows the
   commit to proceed. Non-zero status will cause the commit to fail.
   Parent changeset IDs are in ``$HG_PARENT1`` and ``$HG_PARENT2``.
 
 ``prelistkeys``
   Run before listing pushkeys (like bookmarks) in the
   repository. Non-zero status will cause failure. The key namespace is
   in ``$HG_NAMESPACE``.
 
 ``preoutgoing``
   Run before collecting changes to send from the local repository to
   another. Non-zero status will cause failure. This lets you prevent
   pull over HTTP or SSH. Also prevents against local pull, push
   (outbound) or bundle commands, but not effective, since you can
   just copy files instead then. Source of operation is in
   ``$HG_SOURCE``. If "serve", operation is happening on behalf of remote
   SSH or HTTP repository. If "push", "pull" or "bundle", operation
   is happening on behalf of repository on same system.
 
 ``prepushkey``
   Run before a pushkey (like a bookmark) is added to the
   repository. Non-zero status will cause the key to be rejected. The
   key namespace is in ``$HG_NAMESPACE``, the key is in ``$HG_KEY``,
   the old value (if any) is in ``$HG_OLD``, and the new value is in
   ``$HG_NEW``.
 
 ``pretag``
   Run before creating a tag. Exit status 0 allows the tag to be
   created. Non-zero status will cause the tag to fail. ID of
   changeset to tag is in ``$HG_NODE``. Name of tag is in ``$HG_TAG``. Tag is
   local if ``$HG_LOCAL=1``, in repository if ``$HG_LOCAL=0``.
 
 ``pretxnopen``
   Run before any new repository transaction is open. The reason for the
   transaction will be in ``$HG_TXNNAME`` and a unique identifier for the
   transaction will be in ``HG_TXNID``. A non-zero status will prevent the
   transaction from being opened.
 
 ``pretxnclose``
   Run right before the transaction is actually finalized. Any repository change
   will be visible to the hook program. This lets you validate the transaction
   content or change it. Exit status 0 allows the commit to proceed. Non-zero
   status will cause the transaction to be rolled back. The reason for the
   transaction opening will be in ``$HG_TXNNAME`` and a unique identifier for
   the transaction will be in ``HG_TXNID``. The rest of the available data will
   vary according the transaction type. New changesets will add ``$HG_NODE`` (id
   of the first added changeset), ``$HG_NODE_LAST`` (id of the last added
   changeset), ``$HG_URL`` and ``$HG_SOURCE`` variables, bookmarks and phases
   changes will set ``HG_BOOKMARK_MOVED`` and ``HG_PHASES_MOVED`` to ``1``, etc.
 
 ``txnclose``
   Run after any repository transaction has been committed. At this
   point, the transaction can no longer be rolled back. The hook will run
   after the lock is released. See :hg:`help config.hooks.pretxnclose` docs for
   details about available variables.
 
 ``txnabort``
   Run when a transaction is aborted. See :hg:`help config.hooks.pretxnclose`
   docs for details about available variables.
 
 ``pretxnchangegroup``
   Run after a changegroup has been added via push, pull or unbundle, but before
   the transaction has been committed. Changegroup is visible to hook program.
   This lets you validate incoming changes before accepting them. Passed the ID
   of the first new changeset in ``$HG_NODE`` and last in ``$HG_NODE_LAST``.
   Exit status 0 allows the transaction to commit. Non-zero status will cause
   the transaction to be rolled back and the push, pull or unbundle will fail.
   URL that was source of changes is in ``$HG_URL``.
 
 ``pretxncommit``
   Run after a changeset has been created but the transaction not yet
   committed. Changeset is visible to hook program. This lets you
   validate commit message and changes. Exit status 0 allows the
   commit to proceed. Non-zero status will cause the transaction to
   be rolled back. ID of changeset is in ``$HG_NODE``. Parent changeset
   IDs are in ``$HG_PARENT1`` and ``$HG_PARENT2``.
 
 ``preupdate``
   Run before updating the working directory. Exit status 0 allows
   the update to proceed. Non-zero status will prevent the update.
   Changeset ID of first new parent is in ``$HG_PARENT1``. If merge, ID
   of second new parent is in ``$HG_PARENT2``.
 
 ``listkeys``
   Run after listing pushkeys (like bookmarks) in the repository. The
   key namespace is in ``$HG_NAMESPACE``. ``$HG_VALUES`` is a
   dictionary containing the keys and values.
 
 ``pushkey``
   Run after a pushkey (like a bookmark) is added to the
   repository. The key namespace is in ``$HG_NAMESPACE``, the key is in
   ``$HG_KEY``, the old value (if any) is in ``$HG_OLD``, and the new
   value is in ``$HG_NEW``.
 
 ``tag``
   Run after a tag is created. ID of tagged changeset is in ``$HG_NODE``.
   Name of tag is in ``$HG_TAG``. Tag is local if ``$HG_LOCAL=1``, in
   repository if ``$HG_LOCAL=0``.
 
 ``update``
   Run after updating the working directory. Changeset ID of first
   new parent is in ``$HG_PARENT1``. If merge, ID of second new parent is
   in ``$HG_PARENT2``. If the update succeeded, ``$HG_ERROR=0``. If the
   update failed (e.g. because conflicts not resolved), ``$HG_ERROR=1``.
 
 .. note::
 
    It is generally better to use standard hooks rather than the
    generic pre- and post- command hooks as they are guaranteed to be
    called in the appropriate contexts for influencing transactions.
    Also, hooks like "commit" will be called in all contexts that
    generate a commit (e.g. tag) and not just the commit command.
 
 .. note::
 
    Environment variables with empty values may not be passed to
    hooks on platforms such as Windows. As an example, ``$HG_PARENT2``
    will have an empty value under Unix-like platforms for non-merge
    changesets, while it will not be available at all under Windows.
 
 The syntax for Python hooks is as follows::
 
   hookname = python:modulename.submodule.callable
   hookname = python:/path/to/python/module.py:callable
 
 Python hooks are run within the Mercurial process. Each hook is
 called with at least three keyword arguments: a ui object (keyword
 ``ui``), a repository object (keyword ``repo``), and a ``hooktype``
 keyword that tells what kind of hook is used. Arguments listed as
 environment variables above are passed as keyword arguments, with no
 ``HG_`` prefix, and names in lower case.
 
 If a Python hook returns a "true" value or raises an exception, this
 is treated as a failure.
 
 
 ``hostfingerprints``
 --------------------
 
 (Deprecated. Use ``[hostsecurity]``'s ``fingerprints`` options instead.)
 
 Fingerprints of the certificates of known HTTPS servers.
 
 A HTTPS connection to a server with a fingerprint configured here will
 only succeed if the servers certificate matches the fingerprint.
 This is very similar to how ssh known hosts works.
 
 The fingerprint is the SHA-1 hash value of the DER encoded certificate.
 Multiple values can be specified (separated by spaces or commas). This can
 be used to define both old and new fingerprints while a host transitions
 to a new certificate.
 
 The CA chain and web.cacerts is not used for servers with a fingerprint.
 
 For example::
 
     [hostfingerprints]
     hg.intevation.de = fc:e2:8d:d9:51:cd:cb:c1:4d:18:6b:b7:44:8d:49:72:57:e6:cd:33
     hg.intevation.org = fc:e2:8d:d9:51:cd:cb:c1:4d:18:6b:b7:44:8d:49:72:57:e6:cd:33
 
 ``hostsecurity``
 ----------------
 
-Used to specify per-host security settings.
-
-Options in this section have the form ``hostname``:``setting``. This allows
-multiple settings to be defined on a per-host basis.
+Used to specify global and per-host security settings for connecting to
+other machines.
+
+The following options control default behavior for all hosts.
+
+``minimumprotocol``
+    Defines the minimum channel encryption protocol to use.
+
+    By default, the highest version of TLS - 1.0 or greater - supported by
+    both client and server is used.
+
+    Allowed values are: ``tls1.0`` (the default), ``tls1.1``, ``tls1.2``.
+
+Options in the ``[hostsecurity]`` section can have the form
+``hostname``:``setting``. This allows multiple settings to be defined on a
+per-host basis.
 
 The following per-host settings can be defined.
 
 ``fingerprints``
     A list of hashes of the DER encoded peer/remote certificate. Values have
     the form ``algorithm``:``fingerprint``. e.g.
     ``sha256:c3ab8ff13720e8ad9047dd39466b3c8974e592c2fa383d4a3960714caef0c4f2``.
 
     The following algorithms/prefixes are supported: ``sha1``, ``sha256``,
     ``sha512``.
 
     Use of ``sha256`` or ``sha512`` is preferred.
 
     If a fingerprint is specified, the CA chain is not validated for this
     host and Mercurial will require the remote certificate to match one
     of the fingerprints specified. This means if the server updates its
     certificate, Mercurial will abort until a new fingerprint is defined.
     This can provide stronger security than traditional CA-based validation
     at the expense of convenience.
 
     This option takes precedence over ``verifycertsfile``.
 
+``minimumprotocol``
+    This behaves like ``minimumprotocol`` as described above except it
+    only applies to the host on which it is defined.
+
 ``verifycertsfile``
     Path to file a containing a list of PEM encoded certificates used to
     verify the server certificate. Environment variables and ``~user``
     constructs are expanded in the filename.
 
     The server certificate or the certificate's certificate authority (CA)
     must match a certificate from this file or certificate verification
     will fail and connections to the server will be refused.
 
     If defined, only certificates provided by this file will be used:
     ``web.cacerts`` and any system/default certificates will not be
     used.
 
     This option has no effect if the per-host ``fingerprints`` option
     is set.
 
     The format of the file is as follows:
 
         -----BEGIN CERTIFICATE-----
         ... (certificate in base64 PEM encoding) ...
         -----END CERTIFICATE-----
         -----BEGIN CERTIFICATE-----
         ... (certificate in base64 PEM encoding) ...
         -----END CERTIFICATE-----
 
 For example::
 
     [hostsecurity]
     hg.example.com:fingerprints = sha256:c3ab8ff13720e8ad9047dd39466b3c8974e592c2fa383d4a3960714caef0c4f2
     hg2.example.com:fingerprints = sha1:914f1aff87249c09b6859b88b1906d30756491ca, sha1:fc:e2:8d:d9:51:cd:cb:c1:4d:18:6b:b7:44:8d:49:72:57:e6:cd:33
     foo.example.com:verifycertsfile = /etc/ssl/trusted-ca-certs.pem
 
+To change the default minimum protocol version to TLS 1.2 but to allow TLS 1.1
+when connecting to ``hg.example.com``::
+
+    [hostsecurity]
+    minimumprotocol = tls1.2
+    hg.example.com:minimumprotocol = tls1.1
+
 ``http_proxy``
 --------------
 
 Used to access web-based Mercurial repositories through a HTTP
 proxy.
 
 ``host``
     Host name and (optional) port of the proxy server, for example
     "myproxy:8000".
 
 ``no``
     Optional. Comma-separated list of host names that should bypass
     the proxy.
 
 ``passwd``
     Optional. Password to authenticate with at the proxy server.
 
 ``user``
     Optional. User name to authenticate with at the proxy server.
 
 ``always``
     Optional. Always use the proxy, even for localhost and any entries
     in ``http_proxy.no``. (default: False)
 
 ``merge``
 ---------
 
 This section specifies behavior during merges and updates.
 
 ``checkignored``
    Controls behavior when an ignored file on disk has the same name as a tracked
    file in the changeset being merged or updated to, and has different
    contents. Options are ``abort``, ``warn`` and ``ignore``. With ``abort``,
    abort on such files. With ``warn``, warn on such files and back them up as
    ``.orig``. With ``ignore``, don't print a warning and back them up as
    ``.orig``. (default: ``abort``)
 
 ``checkunknown``
    Controls behavior when an unknown file that isn't ignored has the same name
    as a tracked file in the changeset being merged or updated to, and has
    different contents. Similar to ``merge.checkignored``, except for files that
    are not ignored. (default: ``abort``)
 
 ``merge-patterns``
 ------------------
 
 This section specifies merge tools to associate with particular file
 patterns. Tools matched here will take precedence over the default
 merge tool. Patterns are globs by default, rooted at the repository
 root.
 
 Example::
 
   [merge-patterns]
   **.c = kdiff3
   **.jpg = myimgmerge
 
 ``merge-tools``
 ---------------
 
 This section configures external merge tools to use for file-level
 merges. This section has likely been preconfigured at install time.
 Use :hg:`config merge-tools` to check the existing configuration.
 Also see :hg:`help merge-tools` for more details.
 
 Example ``~/.hgrc``::
 
   [merge-tools]
   # Override stock tool location
   kdiff3.executable = ~/bin/kdiff3
   # Specify command line
   kdiff3.args = $base $local $other -o $output
   # Give higher priority
   kdiff3.priority = 1
 
   # Changing the priority of preconfigured tool
   meld.priority = 0
 
   # Disable a preconfigured tool
   vimdiff.disabled = yes
 
   # Define new tool
   myHtmlTool.args = -m $local $other $base $output
   myHtmlTool.regkey = Software\FooSoftware\HtmlMerge
   myHtmlTool.priority = 1
 
 Supported arguments:
 
 ``priority``
   The priority in which to evaluate this tool.
   (default: 0)
 
 ``executable``
   Either just the name of the executable or its pathname.
 
   .. container:: windows
 
     On Windows, the path can use environment variables with ${ProgramFiles}
     syntax.
 
   (default: the tool name)
 
 ``args``
   The arguments to pass to the tool executable. You can refer to the
   files being merged as well as the output file through these
   variables: ``$base``, ``$local``, ``$other``, ``$output``. The meaning
   of ``$local`` and ``$other`` can vary depending on which action is being
   performed. During and update or merge, ``$local`` represents the original
   state of the file, while ``$other`` represents the commit you are updating
   to or the commit you are merging with. During a rebase ``$local``
   represents the destination of the rebase, and ``$other`` represents the
   commit being rebased.
   (default: ``$local $base $other``)
 
 ``premerge``
   Attempt to run internal non-interactive 3-way merge tool before
   launching external tool.  Options are ``true``, ``false``, ``keep`` or
   ``keep-merge3``. The ``keep`` option will leave markers in the file if the
   premerge fails. The ``keep-merge3`` will do the same but include information
   about the base of the merge in the marker (see internal :merge3 in
   :hg:`help merge-tools`).
   (default: True)
 
 ``binary``
   This tool can merge binary files. (default: False, unless tool
   was selected by file pattern match)
 
 ``symlink``
   This tool can merge symlinks. (default: False)
 
 ``check``
   A list of merge success-checking options:
 
   ``changed``
     Ask whether merge was successful when the merged file shows no changes.
   ``conflicts``
     Check whether there are conflicts even though the tool reported success.
   ``prompt``
     Always prompt for merge success, regardless of success reported by tool.
 
 ``fixeol``
   Attempt to fix up EOL changes caused by the merge tool.
   (default: False)
 
 ``gui``
   This tool requires a graphical interface to run. (default: False)
 
 .. container:: windows
 
   ``regkey``
     Windows registry key which describes install location of this
     tool. Mercurial will search for this key first under
     ``HKEY_CURRENT_USER`` and then under ``HKEY_LOCAL_MACHINE``.
     (default: None)
 
   ``regkeyalt``
     An alternate Windows registry key to try if the first key is not
     found.  The alternate key uses the same ``regname`` and ``regappend``
     semantics of the primary key.  The most common use for this key
     is to search for 32bit applications on 64bit operating systems.
     (default: None)
 
   ``regname``
     Name of value to read from specified registry key.
     (default: the unnamed (default) value)
 
   ``regappend``
     String to append to the value read from the registry, typically
     the executable name of the tool.
     (default: None)
 
 
 ``patch``
 ---------
 
 Settings used when applying patches, for instance through the 'import'
 command or with Mercurial Queues extension.
 
 ``eol``
     When set to 'strict' patch content and patched files end of lines
     are preserved. When set to ``lf`` or ``crlf``, both files end of
     lines are ignored when patching and the result line endings are
     normalized to either LF (Unix) or CRLF (Windows). When set to
     ``auto``, end of lines are again ignored while patching but line
     endings in patched files are normalized to their original setting
     on a per-file basis. If target file does not exist or has no end
     of line, patch line endings are preserved.
     (default: strict)
 
 ``fuzz``
     The number of lines of 'fuzz' to allow when applying patches. This
     controls how much context the patcher is allowed to ignore when
     trying to apply a patch.
     (default: 2)
 
 ``paths``
 ---------
 
 Assigns symbolic names and behavior to repositories.
 
 Options are symbolic names defining the URL or directory that is the
 location of the repository. Example::
 
     [paths]
     my_server = https://example.com/my_repo
     local_path = /home/me/repo
 
 These symbolic names can be used from the command line. To pull
 from ``my_server``: :hg:`pull my_server`. To push to ``local_path``:
 :hg:`push local_path`.
 
 Options containing colons (``:``) denote sub-options that can influence
 behavior for that specific path. Example::
 
     [paths]
     my_server = https://example.com/my_path
     my_server:pushurl = ssh://example.com/my_path
 
 The following sub-options can be defined:
 
 ``pushurl``
    The URL to use for push operations. If not defined, the location
    defined by the path's main entry is used.
 
 ``pushrev``
    A revset defining which revisions to push by default.
 
    When :hg:`push` is executed without a ``-r`` argument, the revset
    defined by this sub-option is evaluated to determine what to push.
 
    For example, a value of ``.`` will push the working directory's
    revision by default.
 
    Revsets specifying bookmarks will not result in the bookmark being
    pushed.
 
 The following special named paths exist:
 
 ``default``
    The URL or directory to use when no source or remote is specified.
 
    :hg:`clone` will automatically define this path to the location the
    repository was cloned from.
 
 ``default-push``
    (deprecated) The URL or directory for the default :hg:`push` location.
    ``default:pushurl`` should be used instead.
 
 ``phases``
 ----------
 
 Specifies default handling of phases. See :hg:`help phases` for more
 information about working with phases.
 
 ``publish``
     Controls draft phase behavior when working as a server. When true,
     pushed changesets are set to public in both client and server and
     pulled or cloned changesets are set to public in the client.
     (default: True)
 
 ``new-commit``
     Phase of newly-created commits.
     (default: draft)
 
 ``checksubrepos``
     Check the phase of the current revision of each subrepository. Allowed
     values are "ignore", "follow" and "abort". For settings other than
     "ignore", the phase of the current revision of each subrepository is
     checked before committing the parent repository. If any of those phases is
     greater than the phase of the parent repository (e.g. if a subrepo is in a
     "secret" phase while the parent repo is in "draft" phase), the commit is
     either aborted (if checksubrepos is set to "abort") or the higher phase is
     used for the parent repository commit (if set to "follow").
     (default: follow)
 
 
 ``profiling``
 -------------
 
 Specifies profiling type, format, and file output. Two profilers are
 supported: an instrumenting profiler (named ``ls``), and a sampling
 profiler (named ``stat``).
 
 In this section description, 'profiling data' stands for the raw data
 collected during profiling, while 'profiling report' stands for a
 statistical text report generated from the profiling data. The
 profiling is done using lsprof.
 
 ``type``
     The type of profiler to use.
     (default: ls)
 
     ``ls``
       Use Python's built-in instrumenting profiler. This profiler
       works on all platforms, but each line number it reports is the
       first line of a function. This restriction makes it difficult to
       identify the expensive parts of a non-trivial function.
     ``stat``
       Use a third-party statistical profiler, statprof. This profiler
       currently runs only on Unix systems, and is most useful for
       profiling commands that run for longer than about 0.1 seconds.
 
 ``format``
     Profiling format.  Specific to the ``ls`` instrumenting profiler.
     (default: text)
 
     ``text``
       Generate a profiling report. When saving to a file, it should be
       noted that only the report is saved, and the profiling data is
       not kept.
     ``kcachegrind``
       Format profiling data for kcachegrind use: when saving to a
       file, the generated file can directly be loaded into
       kcachegrind.
 
 ``frequency``
     Sampling frequency.  Specific to the ``stat`` sampling profiler.
     (default: 1000)
 
 ``output``
     File path where profiling data or report should be saved. If the
     file exists, it is replaced. (default: None, data is printed on
     stderr)
 
 ``sort``
     Sort field.  Specific to the ``ls`` instrumenting profiler.
     One of ``callcount``, ``reccallcount``, ``totaltime`` and
     ``inlinetime``.
     (default: inlinetime)
 
 ``limit``
     Number of lines to show. Specific to the ``ls`` instrumenting profiler.
     (default: 30)
 
 ``nested``
     Show at most this number of lines of drill-down info after each main entry.
     This can help explain the difference between Total and Inline.
     Specific to the ``ls`` instrumenting profiler.
     (default: 5)
 
 ``progress``
 ------------
 
 Mercurial commands can draw progress bars that are as informative as
 possible. Some progress bars only offer indeterminate information, while others
 have a definite end point.
 
 ``delay``
     Number of seconds (float) before showing the progress bar. (default: 3)
 
 ``changedelay``
     Minimum delay before showing a new topic. When set to less than 3 * refresh,
     that value will be used instead. (default: 1)
 
 ``refresh``
     Time in seconds between refreshes of the progress bar. (default: 0.1)
 
 ``format``
     Format of the progress bar.
 
     Valid entries for the format field are ``topic``, ``bar``, ``number``,
     ``unit``, ``estimate``, ``speed``, and ``item``. ``item`` defaults to the
     last 20 characters of the item, but this can be changed by adding either
     ``-<num>`` which would take the last num characters, or ``+<num>`` for the
     first num characters.
 
     (default: topic bar number estimate)
 
 ``width``
     If set, the maximum width of the progress information (that is, min(width,
     term width) will be used).
 
 ``clear-complete``
     Clear the progress bar after it's done. (default: True)
 
 ``disable``
     If true, don't show a progress bar.
 
 ``assume-tty``
     If true, ALWAYS show a progress bar, unless disable is given.
 
 ``rebase``
 ----------
 
 ``allowdivergence``
     Default to False, when True allow creating divergence when performing
     rebase of obsolete changesets.
 
 ``revsetalias``
 ---------------
 
 Alias definitions for revsets. See :hg:`help revsets` for details.
 
 ``server``
 ----------
 
 Controls generic server settings.
 
 ``uncompressed``
     Whether to allow clients to clone a repository using the
     uncompressed streaming protocol. This transfers about 40% more
     data than a regular clone, but uses less memory and CPU on both
     server and client. Over a LAN (100 Mbps or better) or a very fast
     WAN, an uncompressed streaming clone is a lot faster (~10x) than a
     regular clone. Over most WAN connections (anything slower than
     about 6 Mbps), uncompressed streaming is slower, because of the
     extra data transfer overhead. This mode will also temporarily hold
     the write lock while determining what data to transfer.
     (default: True)
 
 ``preferuncompressed``
     When set, clients will try to use the uncompressed streaming
     protocol. (default: False)
 
 ``validate``
     Whether to validate the completeness of pushed changesets by
     checking that all new file revisions specified in manifests are
     present. (default: False)
 
 ``maxhttpheaderlen``
     Instruct HTTP clients not to send request headers longer than this
     many bytes. (default: 1024)
 
 ``bundle1``
     Whether to allow clients to push and pull using the legacy bundle1
     exchange format. (default: True)
 
 ``bundle1gd``
     Like ``bundle1`` but only used if the repository is using the
     *generaldelta* storage format. (default: True)
 
 ``bundle1.push``
     Whether to allow clients to push using the legacy bundle1 exchange
     format. (default: True)
 
 ``bundle1gd.push``
     Like ``bundle1.push`` but only used if the repository is using the
     *generaldelta* storage format. (default: True)
 
 ``bundle1.pull``
     Whether to allow clients to pull using the legacy bundle1 exchange
     format. (default: True)
 
 ``bundle1gd.pull``
     Like ``bundle1.pull`` but only used if the repository is using the
     *generaldelta* storage format. (default: True)
 
     Large repositories using the *generaldelta* storage format should
     consider setting this option because converting *generaldelta*
     repositories to the exchange format required by the bundle1 data
     format can consume a lot of CPU.
 
 ``smtp``
 --------
 
 Configuration for extensions that need to send email messages.
 
 ``host``
     Host name of mail server, e.g. "mail.example.com".
 
 ``port``
     Optional. Port to connect to on mail server. (default: 465 if
     ``tls`` is smtps; 25 otherwise)
 
 ``tls``
     Optional. Method to enable TLS when connecting to mail server: starttls,
     smtps or none. (default: none)
 
 ``username``
     Optional. User name for authenticating with the SMTP server.
     (default: None)
 
 ``password``
     Optional. Password for authenticating with the SMTP server. If not
     specified, interactive sessions will prompt the user for a
     password; non-interactive sessions will fail. (default: None)
 
 ``local_hostname``
     Optional. The hostname that the sender can use to identify
     itself to the MTA.
 
 
 ``subpaths``
 ------------
 
 Subrepository source URLs can go stale if a remote server changes name
 or becomes temporarily unavailable. This section lets you define
 rewrite rules of the form::
 
     <pattern> = <replacement>
 
 where ``pattern`` is a regular expression matching a subrepository
 source URL and ``replacement`` is the replacement string used to
 rewrite it. Groups can be matched in ``pattern`` and referenced in
 ``replacements``. For instance::
 
     http://server/(.*)-hg/ = http://hg.server/\1/
 
 rewrites ``http://server/foo-hg/`` into ``http://hg.server/foo/``.
 
 Relative subrepository paths are first made absolute, and the
 rewrite rules are then applied on the full (absolute) path. If ``pattern``
 doesn't match the full path, an attempt is made to apply it on the
 relative path alone. The rules are applied in definition order.
 
 ``templatealias``
 -----------------
 
 Alias definitions for templates. See :hg:`help templates` for details.
 
 ``trusted``
 -----------
 
 Mercurial will not use the settings in the
 ``.hg/hgrc`` file from a repository if it doesn't belong to a trusted
 user or to a trusted group, as various hgrc features allow arbitrary
 commands to be run. This issue is often encountered when configuring
 hooks or extensions for shared repositories or servers. However,
 the web interface will use some safe settings from the ``[web]``
 section.
 
 This section specifies what users and groups are trusted. The
 current user is always trusted. To trust everybody, list a user or a
 group with name ``*``. These settings must be placed in an
 *already-trusted file* to take effect, such as ``$HOME/.hgrc`` of the
 user or service running Mercurial.
 
 ``users``
   Comma-separated list of trusted users.
 
 ``groups``
   Comma-separated list of trusted groups.
 
 
 ``ui``
 ------
 
 User interface controls.
 
 ``archivemeta``
     Whether to include the .hg_archival.txt file containing meta data
     (hashes for the repository base and for tip) in archives created
     by the :hg:`archive` command or downloaded via hgweb.
     (default: True)
 
 ``askusername``
     Whether to prompt for a username when committing. If True, and
     neither ``$HGUSER`` nor ``$EMAIL`` has been specified, then the user will
     be prompted to enter a username. If no username is entered, the
     default ``USER@HOST`` is used instead.
     (default: False)
 
 ``clonebundles``
     Whether the "clone bundles" feature is enabled.
 
     When enabled, :hg:`clone` may download and apply a server-advertised
     bundle file from a URL instead of using the normal exchange mechanism.
 
     This can likely result in faster and more reliable clones.
 
     (default: True)
 
 ``clonebundlefallback``
     Whether failure to apply an advertised "clone bundle" from a server
     should result in fallback to a regular clone.
 
     This is disabled by default because servers advertising "clone
     bundles" often do so to reduce server load. If advertised bundles
     start mass failing and clients automatically fall back to a regular
     clone, this would add significant and unexpected load to the server
     since the server is expecting clone operations to be offloaded to
     pre-generated bundles. Failing fast (the default behavior) ensures
     clients don't overwhelm the server when "clone bundle" application
     fails.
 
     (default: False)
 
 ``clonebundleprefers``
     Defines preferences for which "clone bundles" to use.
 
     Servers advertising "clone bundles" may advertise multiple available
     bundles. Each bundle may have different attributes, such as the bundle
     type and compression format. This option is used to prefer a particular
     bundle over another.
 
     The following keys are defined by Mercurial:
 
     BUNDLESPEC
        A bundle type specifier. These are strings passed to :hg:`bundle -t`.
        e.g. ``gzip-v2`` or ``bzip2-v1``.
 
     COMPRESSION
        The compression format of the bundle. e.g. ``gzip`` and ``bzip2``.
 
     Server operators may define custom keys.
 
     Example values: ``COMPRESSION=bzip2``,
     ``BUNDLESPEC=gzip-v2, COMPRESSION=gzip``.
 
     By default, the first bundle advertised by the server is used.
 
 ``commitsubrepos``
     Whether to commit modified subrepositories when committing the
     parent repository. If False and one subrepository has uncommitted
     changes, abort the commit.
     (default: False)
 
 ``debug``
     Print debugging information. (default: False)
 
 ``editor``
     The editor to use during a commit. (default: ``$EDITOR`` or ``vi``)
 
 ``fallbackencoding``
     Encoding to try if it's not possible to decode the changelog using
     UTF-8. (default: ISO-8859-1)
 
 ``graphnodetemplate``
     The template used to print changeset nodes in an ASCII revision graph.
     (default: ``{graphnode}``)
 
 ``ignore``
     A file to read per-user ignore patterns from. This file should be
     in the same format as a repository-wide .hgignore file. Filenames
     are relative to the repository root. This option supports hook syntax,
     so if you want to specify multiple ignore files, you can do so by
     setting something like ``ignore.other = ~/.hgignore2``. For details
     of the ignore file format, see the ``hgignore(5)`` man page.
 
 ``interactive``
     Allow to prompt the user. (default: True)
 
 ``interface``
     Select the default interface for interactive features (default: text).
     Possible values are 'text' and 'curses'.
 
 ``interface.chunkselector``
     Select the interface for change recording (e.g. :hg:`commit` -i).
     Possible values are 'text' and 'curses'.
     This config overrides the interface specified by ui.interface.
 
 ``logtemplate``
     Template string for commands that print changesets.
 
 ``merge``
     The conflict resolution program to use during a manual merge.
     For more information on merge tools see :hg:`help merge-tools`.
     For configuring merge tools see the ``[merge-tools]`` section.
 
 ``mergemarkers``
     Sets the merge conflict marker label styling. The ``detailed``
     style uses the ``mergemarkertemplate`` setting to style the labels.
     The ``basic`` style just uses 'local' and 'other' as the marker label.
     One of ``basic`` or ``detailed``.
     (default: ``basic``)
 
 ``mergemarkertemplate``
     The template used to print the commit description next to each conflict
     marker during merge conflicts. See :hg:`help templates` for the template
     format.
 
     Defaults to showing the hash, tags, branches, bookmarks, author, and
     the first line of the commit description.
 
     If you use non-ASCII characters in names for tags, branches, bookmarks,
     authors, and/or commit descriptions, you must pay attention to encodings of
     managed files. At template expansion, non-ASCII characters use the encoding
     specified by the ``--encoding`` global option, ``HGENCODING`` or other
     environment variables that govern your locale. If the encoding of the merge
     markers is different from the encoding of the merged files,
     serious problems may occur.
 
 ``origbackuppath``
     The path to a directory used to store generated .orig files. If the path is
     not a directory, one will be created.
 
 ``patch``
     An optional external tool that ``hg import`` and some extensions
     will use for applying patches. By default Mercurial uses an
     internal patch utility. The external tool must work as the common
     Unix ``patch`` program. In particular, it must accept a ``-p``
     argument to strip patch headers, a ``-d`` argument to specify the
     current directory, a file name to patch, and a patch file to take
     from stdin.
 
     It is possible to specify a patch tool together with extra
     arguments. For example, setting this option to ``patch --merge``
     will use the ``patch`` program with its 2-way merge option.
 
 ``portablefilenames``
     Check for portable filenames. Can be ``warn``, ``ignore`` or ``abort``.
     (default: ``warn``)
 
     ``warn``
       Print a warning message on POSIX platforms, if a file with a non-portable
       filename is added (e.g. a file with a name that can't be created on
       Windows because it contains reserved parts like ``AUX``, reserved
       characters like ``:``, or would cause a case collision with an existing
       file).
 
     ``ignore``
       Don't print a warning.
 
     ``abort``
       The command is aborted.
 
     ``true``
       Alias for ``warn``.
 
     ``false``
       Alias for ``ignore``.
 
     .. container:: windows
 
       On Windows, this configuration option is ignored and the command aborted.
 
 ``quiet``
     Reduce the amount of output printed.
     (default: False)
 
 ``remotecmd``
     Remote command to use for clone/push/pull operations.
     (default: ``hg``)
 
 ``report_untrusted``
     Warn if a ``.hg/hgrc`` file is ignored due to not being owned by a
     trusted user or group.
     (default: True)
 
 ``slash``
     Display paths using a slash (``/``) as the path separator. This
     only makes a difference on systems where the default path
     separator is not the slash character (e.g. Windows uses the
     backslash character (``\``)).
     (default: False)
 
 ``statuscopies``
     Display copies in the status command.
 
 ``ssh``
     Command to use for SSH connections. (default: ``ssh``)
 
 ``strict``
     Require exact command names, instead of allowing unambiguous
     abbreviations. (default: False)
 
 ``style``
     Name of style to use for command output.
 
 ``supportcontact``
     A URL where users should report a Mercurial traceback. Use this if you are a
     large organisation with its own Mercurial deployment process and crash
     reports should be addressed to your internal support.
 
 ``textwidth``
     Maximum width of help text. A longer line generated by ``hg help`` or
     ``hg subcommand --help`` will be broken after white space to get this
     width or the terminal width, whichever comes first.
     A non-positive value will disable this and the terminal width will be
     used. (default: 78)
 
 ``timeout``
     The timeout used when a lock is held (in seconds), a negative value
     means no timeout. (default: 600)
 
 ``traceback``
     Mercurial always prints a traceback when an unknown exception
     occurs. Setting this to True will make Mercurial print a traceback
     on all exceptions, even those recognized by Mercurial (such as
     IOError or MemoryError). (default: False)
 
 ``username``
     The committer of a changeset created when running "commit".
     Typically a person's name and email address, e.g. ``Fred Widget
     <[e-mail]>``. Environment variables in the
     username are expanded.
 
     (default: ``$EMAIL`` or ``username@hostname``. If the username in
     hgrc is empty, e.g. if the system admin set ``username =`` in the
     system hgrc, it has to be specified manually or in a different
     hgrc file)
 
 ``verbose``
     Increase the amount of output printed. (default: False)
 
 
 ``web``
 -------
 
 Web interface configuration. The settings in this section apply to
 both the builtin webserver (started by :hg:`serve`) and the script you
 run through a webserver (``hgweb.cgi`` and the derivatives for FastCGI
 and WSGI).
 
 The Mercurial webserver does no authentication (it does not prompt for
 usernames and passwords to validate *who* users are), but it does do
 authorization (it grants or denies access for *authenticated users*
 based on settings in this section). You must either configure your
 webserver to do authentication for you, or disable the authorization
 checks.
 
 For a quick setup in a trusted environment, e.g., a private LAN, where
 you want it to accept pushes from anybody, you can use the following
 command line::
 
     $ hg --config web.allow_push=* --config web.push_ssl=False serve
 
 Note that this will allow anybody to push anything to the server and
 that this should not be used for public servers.
 
 The full set of options is:
 
 ``accesslog``
     Where to output the access log. (default: stdout)
 
 ``address``
     Interface address to bind to. (default: all)
 
 ``allow_archive``
     List of archive format (bz2, gz, zip) allowed for downloading.
     (default: empty)
 
 ``allowbz2``
     (DEPRECATED) Whether to allow .tar.bz2 downloading of repository
     revisions.
     (default: False)
 
 ``allowgz``
     (DEPRECATED) Whether to allow .tar.gz downloading of repository
     revisions.
     (default: False)
 
 ``allowpull``
     Whether to allow pulling from the repository. (default: True)
 
 ``allow_push``
     Whether to allow pushing to the repository. If empty or not set,
     pushing is not allowed. If the special value ``*``, any remote
     user can push, including unauthenticated users. Otherwise, the
     remote user must have been authenticated, and the authenticated
     user name must be present in this list. The contents of the
     allow_push list are examined after the deny_push list.
 
 ``allow_read``
     If the user has not already been denied repository access due to
     the contents of deny_read, this list determines whether to grant
     repository access to the user. If this list is not empty, and the
     user is unauthenticated or not present in the list, then access is
     denied for the user. If the list is empty or not set, then access
     is permitted to all users by default. Setting allow_read to the
     special value ``*`` is equivalent to it not being set (i.e. access
     is permitted to all users). The contents of the allow_read list are
     examined after the deny_read list.
 
 ``allowzip``
     (DEPRECATED) Whether to allow .zip downloading of repository
     revisions. This feature creates temporary files.
     (default: False)
 
 ``archivesubrepos``
     Whether to recurse into subrepositories when archiving.
     (default: False)
 
 ``baseurl``
     Base URL to use when publishing URLs in other locations, so
     third-party tools like email notification hooks can construct
     URLs. Example: ``http://hgserver/repos/``.
 
 ``cacerts``
     Path to file containing a list of PEM encoded certificate
     authority certificates. Environment variables and ``~user``
     constructs are expanded in the filename. If specified on the
     client, then it will verify the identity of remote HTTPS servers
     with these certificates.
 
     To disable SSL verification temporarily, specify ``--insecure`` from
     command line.
 
     You can use OpenSSL's CA certificate file if your platform has
     one. On most Linux systems this will be
     ``/etc/ssl/certs/ca-certificates.crt``. Otherwise you will have to
     generate this file manually. The form must be as follows::
 
         -----BEGIN CERTIFICATE-----
         ... (certificate in base64 PEM encoding) ...
         -----END CERTIFICATE-----
         -----BEGIN CERTIFICATE-----
         ... (certificate in base64 PEM encoding) ...
         -----END CERTIFICATE-----
 
 ``cache``
     Whether to support caching in hgweb. (default: True)
 
 ``certificate``
     Certificate to use when running :hg:`serve`.
 
 ``collapse``
     With ``descend`` enabled, repositories in subdirectories are shown at
     a single level alongside repositories in the current path. With
     ``collapse`` also enabled, repositories residing at a deeper level than
     the current path are grouped behind navigable directory entries that
     lead to the locations of these repositories. In effect, this setting
     collapses each collection of repositories found within a subdirectory
     into a single entry for that subdirectory. (default: False)
 
 ``comparisoncontext``
     Number of lines of context to show in side-by-side file comparison. If
     negative or the value ``full``, whole files are shown. (default: 5)
 
     This setting can be overridden by a ``context`` request parameter to the
     ``comparison`` command, taking the same values.
 
 ``contact``
     Name or email address of the person in charge of the repository.
     (default: ui.username or ``$EMAIL`` or "unknown" if unset or empty)
 
 ``deny_push``
     Whether to deny pushing to the repository. If empty or not set,
     push is not denied. If the special value ``*``, all remote users are
     denied push. Otherwise, unauthenticated users are all denied, and
     any authenticated user name present in this list is also denied. The
     contents of the deny_push list are examined before the allow_push list.
 
 ``deny_read``
     Whether to deny reading/viewing of the repository. If this list is
     not empty, unauthenticated users are all denied, and any
     authenticated user name present in this list is also denied access to
     the repository. If set to the special value ``*``, all remote users
     are denied access (rarely needed ;). If deny_read is empty or not set,
     the determination of repository access depends on the presence and
     content of the allow_read list (see description). If both
     deny_read and allow_read are empty or not set, then access is
     permitted to all users by default. If the repository is being
     served via hgwebdir, denied users will not be able to see it in
     the list of repositories. The contents of the deny_read list have
     priority over (are examined before) the contents of the allow_read
     list.
 
 ``descend``
     hgwebdir indexes will not descend into subdirectories. Only repositories
     directly in the current path will be shown (other repositories are still
     available from the index corresponding to their containing path).
 
 ``description``
     Textual description of the repository's purpose or contents.
     (default: "unknown")
 
 ``encoding``
     Character encoding name. (default: the current locale charset)
     Example: "UTF-8".
 
 ``errorlog``
     Where to output the error log. (default: stderr)
 
 ``guessmime``
     Control MIME types for raw download of file content.
     Set to True to let hgweb guess the content type from the file
     extension. This will serve HTML files as ``text/html`` and might
     allow cross-site scripting attacks when serving untrusted
     repositories. (default: False)
 
 ``hidden``
     Whether to hide the repository in the hgwebdir index.
     (default: False)
 
 ``ipv6``
     Whether to use IPv6. (default: False)
 
 ``labels``
     List of string *labels* associated with the repository.
 
     Labels are exposed as a template keyword and can be used to customize
     output. e.g. the ``index`` template can group or filter repositories
     by labels and the ``summary`` template can display additional content
     if a specific label is present.
 
 ``logoimg``
     File name of the logo image that some templates display on each page.
     The file name is relative to ``staticurl``. That is, the full path to
     the logo image is "staticurl/logoimg".
     If unset, ``hglogo.png`` will be used.
 
 ``logourl``
     Base URL to use for logos. If unset, ``https://mercurial-scm.org/``
     will be used.
 
 ``maxchanges``
     Maximum number of changes to list on the changelog. (default: 10)
 
 ``maxfiles``
     Maximum number of files to list per changeset. (default: 10)
 
 ``maxshortchanges``
     Maximum number of changes to list on the shortlog, graph or filelog
     pages. (default: 60)
 
 ``name``
     Repository name to use in the web interface.
     (default: current working directory)
 
 ``port``
     Port to listen on. (default: 8000)
 
 ``prefix``
     Prefix path to serve from. (default: '' (server root))
 
 ``push_ssl``
     Whether to require that inbound pushes be transported over SSL to
     prevent password sniffing. (default: True)
 
 ``refreshinterval``
     How frequently directory listings re-scan the filesystem for new
     repositories, in seconds. This is relevant when wildcards are used
     to define paths. Depending on how much filesystem traversal is
     required, refreshing may negatively impact performance.
 
     Values less than or equal to 0 always refresh.
     (default: 20)
 
 ``staticurl``
     Base URL to use for static files. If unset, static files (e.g. the
     hgicon.png favicon) will be served by the CGI script itself. Use
     this setting to serve them directly with the HTTP server.
     Example: ``http://hgserver/static/``.
 
 ``stripes``
     How many lines a "zebra stripe" should span in multi-line output.
     Set to 0 to disable. (default: 1)
 
 ``style``
     Which template map style to use. The available options are the names of
     subdirectories in the HTML templates path. (default: ``paper``)
     Example: ``monoblue``.
 
 ``templates``
     Where to find the HTML templates. The default path to the HTML templates
     can be obtained from ``hg debuginstall``.
 
 ``websub``
 ----------
 
 Web substitution filter definition. You can use this section to
 define a set of regular expression substitution patterns which
 let you automatically modify the hgweb server output.
 
 The default hgweb templates only apply these substitution patterns
 on the revision description fields. You can apply them anywhere
 you want when you create your own templates by adding calls to the
 "websub" filter (usually after calling the "escape" filter).
 
 This can be used, for example, to convert issue references to links
 to your issue tracker, or to convert "markdown-like" syntax into
 HTML (see the examples below).
 
 Each entry in this section names a substitution filter.
 The value of each entry defines the substitution expression itself.
 The websub expressions follow the old interhg extension syntax,
 which in turn imitates the Unix sed replacement syntax::
 
     patternname = s/SEARCH_REGEX/REPLACE_EXPRESSION/[i]
 
 You can use any separator other than "/". The final "i" is optional
 and indicates that the search must be case insensitive.
 
 Examples::
 
     [websub]
     issues = s|issue(\d+)|<a href="http://bts.example.org/issue\1">issue\1</a>|i
     italic = s/\b_(\S+)_\b/<i>\1<\/i>/
     bold = s/\*\b(\S+)\b\*/<b>\1<\/b>/
 
 ``worker``
 ----------
 
 Parallel master/worker configuration. We currently perform working
 directory updates in parallel on Unix-like systems, which greatly
 helps performance.
 
 ``numcpus``
     Number of CPUs to use for parallel operations. A zero or
     negative value is treated as ``use the default``.
     (default: 4 or the number of CPUs on the system, whichever is larger)
 
 ``backgroundclose``
     Whether to enable closing file handles on background threads during certain
     operations. Some platforms aren't very efficient at closing file
     handles that have been written or appended to. By performing file closing
     on background threads, file write rate can increase substantially.
     (default: true on Windows, false elsewhere)
 
 ``backgroundcloseminfilecount``
     Minimum number of files required to trigger background file closing.
     Operations not writing this many files won't start background close
     threads.
     (default: 2048)
 
 ``backgroundclosemaxqueue``
     The maximum number of opened file handles waiting to be closed in the
     background. This option only has an effect if ``backgroundclose`` is
     enabled.
     (default: 384)
 
 ``backgroundclosethreadcount``
     Number of threads to process background file closes. Only relevant if
     ``backgroundclose`` is enabled.
     (default: 4)

mercurial/sslutil.py

@@ -1,666 +1,733
 # sslutil.py - SSL handling for mercurial
 #
 # Copyright 2005, 2006, 2007, 2008 Matt Mackall <[e-mail]>
 # Copyright 2006, 2007 Alexis S. L. Carvalho <[e-mail]>
 # Copyright 2006 Vadim Gelfer <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
 import hashlib
 import os
 import re
 import ssl
 import sys
 
 from .i18n import _
 from . import (
     error,
     util,
 )
 
 # Python 2.7.9+ overhauled the built-in SSL/TLS features of Python. It added
 # support for TLS 1.1, TLS 1.2, SNI, system CA stores, etc. These features are
 # all exposed via the "ssl" module.
 #
 # Depending on the version of Python being used, SSL/TLS support is either
 # modern/secure or legacy/insecure. Many operations in this module have
 # separate code paths depending on support in Python.
 
-hassni = getattr(ssl, 'HAS_SNI', False)
+configprotocols = set([
+    'tls1.0',
+    'tls1.1',
+    'tls1.2',
+])
 
-try:
-    OP_NO_SSLv2 = ssl.OP_NO_SSLv2
-    OP_NO_SSLv3 = ssl.OP_NO_SSLv3
-except AttributeError:
-    OP_NO_SSLv2 = 0x1000000
-    OP_NO_SSLv3 = 0x2000000
+hassni = getattr(ssl, 'HAS_SNI', False)
 
 try:
     # ssl.SSLContext was added in 2.7.9 and presence indicates modern
     # SSL/TLS features are available.
     SSLContext = ssl.SSLContext
     modernssl = True
     _canloaddefaultcerts = util.safehasattr(SSLContext, 'load_default_certs')
 except AttributeError:
     modernssl = False
     _canloaddefaultcerts = False
 
     # We implement SSLContext using the interface from the standard library.
     class SSLContext(object):
         # ssl.wrap_socket gained the "ciphers" named argument in 2.7.
         _supportsciphers = sys.version_info >= (2, 7)
 
         def __init__(self, protocol):
             # From the public interface of SSLContext
             self.protocol = protocol
             self.check_hostname = False
             self.options = 0
             self.verify_mode = ssl.CERT_NONE
 
             # Used by our implementation.
             self._certfile = None
             self._keyfile = None
             self._certpassword = None
             self._cacerts = None
             self._ciphers = None
 
         def load_cert_chain(self, certfile, keyfile=None, password=None):
             self._certfile = certfile
             self._keyfile = keyfile
             self._certpassword = password
 
         def load_default_certs(self, purpose=None):
             pass
 
         def load_verify_locations(self, cafile=None, capath=None, cadata=None):
             if capath:
                 raise error.Abort(_('capath not supported'))
             if cadata:
                 raise error.Abort(_('cadata not supported'))
 
             self._cacerts = cafile
 
         def set_ciphers(self, ciphers):
             if not self._supportsciphers:
                 raise error.Abort(_('setting ciphers not supported'))
 
             self._ciphers = ciphers
 
         def wrap_socket(self, socket, server_hostname=None, server_side=False):
             # server_hostname is unique to SSLContext.wrap_socket and is used
             # for SNI in that context. So there's nothing for us to do with it
             # in this legacy code since we don't support SNI.
 
             args = {
                 'keyfile': self._keyfile,
                 'certfile': self._certfile,
                 'server_side': server_side,
                 'cert_reqs': self.verify_mode,
                 'ssl_version': self.protocol,
                 'ca_certs': self._cacerts,
             }
 
             if self._supportsciphers:
                 args['ciphers'] = self._ciphers
 
             return ssl.wrap_socket(socket, **args)
 
 def _hostsettings(ui, hostname):
     """Obtain security settings for a hostname.
 
     Returns a dict of settings relevant to that hostname.
     """
     s = {
         # Whether we should attempt to load default/available CA certs
         # if an explicit ``cafile`` is not defined.
         'allowloaddefaultcerts': True,
         # List of 2-tuple of (hash algorithm, hash).
         'certfingerprints': [],
         # Path to file containing concatenated CA certs. Used by
         # SSLContext.load_verify_locations().
         'cafile': None,
         # Whether certificate verification should be disabled.
         'disablecertverification': False,
         # Whether the legacy [hostfingerprints] section has data for this host.
         'legacyfingerprint': False,
         # PROTOCOL_* constant to use for SSLContext.__init__.
         'protocol': None,
         # ssl.CERT_* constant used by SSLContext.verify_mode.
         'verifymode': None,
         # Defines extra ssl.OP* bitwise options to set.
         'ctxoptions': None,
     }
 
     # Despite its name, PROTOCOL_SSLv23 selects the highest protocol
     # that both ends support, including TLS protocols. On legacy stacks,
-    # the highest it likely goes in TLS 1.0. On modern stacks, it can
+    # the highest it likely goes is TLS 1.0. On modern stacks, it can
     # support TLS 1.2.
     #
     # The PROTOCOL_TLSv* constants select a specific TLS version
     # only (as opposed to multiple versions). So the method for
     # supporting multiple TLS versions is to use PROTOCOL_SSLv23 and
     # disable protocols via SSLContext.options and OP_NO_* constants.
     # However, SSLContext.options doesn't work unless we have the
     # full/real SSLContext available to us.
-    if modernssl:
-        s['protocol'] = ssl.PROTOCOL_SSLv23
-    else:
-        s['protocol'] = ssl.PROTOCOL_TLSv1
+
+    # Allow minimum TLS protocol to be specified in the config.
+    def validateprotocol(protocol, key):
+        if protocol not in configprotocols:
+            raise error.Abort(
+                _('unsupported protocol from hostsecurity.%s: %s') %
+                (key, protocol),
+                hint=_('valid protocols: %s') %
+                     ' '.join(sorted(configprotocols)))
 
-    # SSLv2 and SSLv3 are broken. We ban them outright.
-    # WARNING: ctxoptions doesn't have an effect unless the modern ssl module
-    # is available. Be careful when adding flags!
-    s['ctxoptions'] = OP_NO_SSLv2 | OP_NO_SSLv3
+    key = 'minimumprotocol'
+    # Default to TLS 1.0+ as that is what browsers are currently doing.
+    protocol = ui.config('hostsecurity', key, 'tls1.0')
+    validateprotocol(protocol, key)
 
-    # Prevent CRIME.
-    # There is no guarantee this attribute is defined on the module.
-    s['ctxoptions'] |= getattr(ssl, 'OP_NO_COMPRESSION', 0)
+    key = '%s:minimumprotocol' % hostname
+    protocol = ui.config('hostsecurity', key, protocol)
+    validateprotocol(protocol, key)
+
+    s['protocol'], s['ctxoptions'] = protocolsettings(protocol)
 
     # Look for fingerprints in [hostsecurity] section. Value is a list
     # of <alg>:<fingerprint> strings.
     fingerprints = ui.configlist('hostsecurity', '%s:fingerprints' % hostname,
                                  [])
     for fingerprint in fingerprints:
         if not (fingerprint.startswith(('sha1:', 'sha256:', 'sha512:'))):
             raise error.Abort(_('invalid fingerprint for %s: %s') % (
                                 hostname, fingerprint),
                               hint=_('must begin with "sha1:", "sha256:", '
                                      'or "sha512:"'))
 
         alg, fingerprint = fingerprint.split(':', 1)
         fingerprint = fingerprint.replace(':', '').lower()
         s['certfingerprints'].append((alg, fingerprint))
 
     # Fingerprints from [hostfingerprints] are always SHA-1.
     for fingerprint in ui.configlist('hostfingerprints', hostname, []):
         fingerprint = fingerprint.replace(':', '').lower()
         s['certfingerprints'].append(('sha1', fingerprint))
         s['legacyfingerprint'] = True
 
     # If a host cert fingerprint is defined, it is the only thing that
     # matters. No need to validate CA certs.
     if s['certfingerprints']:
         s['verifymode'] = ssl.CERT_NONE
         s['allowloaddefaultcerts'] = False
 
     # If --insecure is used, don't take CAs into consideration.
     elif ui.insecureconnections:
         s['disablecertverification'] = True
         s['verifymode'] = ssl.CERT_NONE
         s['allowloaddefaultcerts'] = False
 
     if ui.configbool('devel', 'disableloaddefaultcerts'):
         s['allowloaddefaultcerts'] = False
 
     # If both fingerprints and a per-host ca file are specified, issue a warning
     # because users should not be surprised about what security is or isn't
     # being performed.
     cafile = ui.config('hostsecurity', '%s:verifycertsfile' % hostname)
     if s['certfingerprints'] and cafile:
         ui.warn(_('(hostsecurity.%s:verifycertsfile ignored when host '
                   'fingerprints defined; using host fingerprints for '
                   'verification)\n') % hostname)
 
     # Try to hook up CA certificate validation unless something above
     # makes it not necessary.
     if s['verifymode'] is None:
         # Look at per-host ca file first.
         if cafile:
             cafile = util.expandpath(cafile)
             if not os.path.exists(cafile):
                 raise error.Abort(_('path specified by %s does not exist: %s') %
                                   ('hostsecurity.%s:verifycertsfile' % hostname,
                                    cafile))
             s['cafile'] = cafile
         else:
             # Find global certificates file in config.
             cafile = ui.config('web', 'cacerts')
 
             if cafile:
                 cafile = util.expandpath(cafile)
                 if not os.path.exists(cafile):
                     raise error.Abort(_('could not find web.cacerts: %s') %
                                       cafile)
             elif s['allowloaddefaultcerts']:
                 # CAs not defined in config. Try to find system bundles.
                 cafile = _defaultcacerts(ui)
                 if cafile:
                     ui.debug('using %s for CA file\n' % cafile)
 
             s['cafile'] = cafile
 
         # Require certificate validation if CA certs are being loaded and
         # verification hasn't been disabled above.
         if cafile or (_canloaddefaultcerts and s['allowloaddefaultcerts']):
             s['verifymode'] = ssl.CERT_REQUIRED
         else:
             # At this point we don't have a fingerprint, aren't being
             # explicitly insecure, and can't load CA certs. Connecting
             # is insecure. We allow the connection and abort during
             # validation (once we have the fingerprint to print to the
             # user).
             s['verifymode'] = ssl.CERT_NONE
 
     assert s['protocol'] is not None
     assert s['ctxoptions'] is not None
     assert s['verifymode'] is not None
 
     return s
 
+def protocolsettings(protocol):
+    """Resolve the protocol and context options for a config value."""
+    if protocol not in configprotocols:
+        raise ValueError('protocol value not supported: %s' % protocol)
+
+    # Legacy ssl module only supports up to TLS 1.0. Ideally we'd use
+    # PROTOCOL_SSLv23 and options to disable SSLv2 and SSLv3. However,
+    # SSLContext.options doesn't work in our implementation since we use
+    # a fake SSLContext on these Python versions.
+    if not modernssl:
+        if protocol != 'tls1.0':
+            raise error.Abort(_('current Python does not support protocol '
+                                'setting %s') % protocol,
+                              hint=_('upgrade Python or disable setting since '
+                                     'only TLS 1.0 is supported'))
+
+        return ssl.PROTOCOL_TLSv1, 0
+
+    # WARNING: returned options don't work unless the modern ssl module
+    # is available. Be careful when adding options here.
+
+    # SSLv2 and SSLv3 are broken. We ban them outright.
+    options = ssl.OP_NO_SSLv2 | ssl.OP_NO_SSLv3
+
+    if protocol == 'tls1.0':
+        # Defaults above are to use TLS 1.0+
+        pass
+    elif protocol == 'tls1.1':
+        options |= ssl.OP_NO_TLSv1
+    elif protocol == 'tls1.2':
+        options |= ssl.OP_NO_TLSv1 | ssl.OP_NO_TLSv1_1
+    else:
+        raise error.Abort(_('this should not happen'))
+
+    # Prevent CRIME.
+    # There is no guarantee this attribute is defined on the module.
+    options |= getattr(ssl, 'OP_NO_COMPRESSION', 0)
+
+    return ssl.PROTOCOL_SSLv23, options
+
 def wrapsocket(sock, keyfile, certfile, ui, serverhostname=None):
     """Add SSL/TLS to a socket.
 
     This is a glorified wrapper for ``ssl.wrap_socket()``. It makes sane
     choices based on what security options are available.
 
     In addition to the arguments supported by ``ssl.wrap_socket``, we allow
     the following additional arguments:
 
     * serverhostname - The expected hostname of the remote server. If the
       server (and client) support SNI, this tells the server which certificate
       to use.
     """
     if not serverhostname:
         raise error.Abort(_('serverhostname argument is required'))
 
     settings = _hostsettings(ui, serverhostname)
 
     # We can't use ssl.create_default_context() because it calls
     # load_default_certs() unless CA arguments are passed to it. We want to
     # have explicit control over CA loading because implicitly loading
     # CAs may undermine the user's intent. For example, a user may define a CA
     # bundle with a specific CA cert removed. If the system/default CA bundle
     # is loaded and contains that removed CA, you've just undone the user's
     # choice.
     sslcontext = SSLContext(settings['protocol'])
 
     # This is a no-op unless using modern ssl.
     sslcontext.options |= settings['ctxoptions']
 
     # This still works on our fake SSLContext.
     sslcontext.verify_mode = settings['verifymode']
 
     if certfile is not None:
         def password():
             f = keyfile or certfile
             return ui.getpass(_('passphrase for %s: ') % f, '')
         sslcontext.load_cert_chain(certfile, keyfile, password)
 
     if settings['cafile'] is not None:
         try:
             sslcontext.load_verify_locations(cafile=settings['cafile'])
         except ssl.SSLError as e:
             raise error.Abort(_('error loading CA file %s: %s') % (
                               settings['cafile'], e.args[1]),
                               hint=_('file is empty or malformed?'))
         caloaded = True
     elif settings['allowloaddefaultcerts']:
         # This is a no-op on old Python.
         sslcontext.load_default_certs()
         caloaded = True
     else:
         caloaded = False
 
     try:
         sslsocket = sslcontext.wrap_socket(sock, server_hostname=serverhostname)
-    except ssl.SSLError:
+    except ssl.SSLError as e:
         # If we're doing certificate verification and no CA certs are loaded,
         # that is almost certainly the reason why verification failed. Provide
         # a hint to the user.
         # Only modern ssl module exposes SSLContext.get_ca_certs() so we can
         # only show this warning if modern ssl is available.
         if (caloaded and settings['verifymode'] == ssl.CERT_REQUIRED and
             modernssl and not sslcontext.get_ca_certs()):
             ui.warn(_('(an attempt was made to load CA certificates but none '
                       'were loaded; see '
                       'https://mercurial-scm.org/wiki/SecureConnections for '
                       'how to configure Mercurial to avoid this error)\n'))
+        # Try to print more helpful error messages for known failures.
+        if util.safehasattr(e, 'reason'):
+            if e.reason == 'UNSUPPORTED_PROTOCOL':
+                ui.warn(_('(could not negotiate a common protocol; see '
+                          'https://mercurial-scm.org/wiki/SecureConnections '
+                          'for how to configure Mercurial to avoid this '
+                          'error)\n'))
         raise
 
     # check if wrap_socket failed silently because socket had been
     # closed
     # - see http://bugs.python.org/issue13721
     if not sslsocket.cipher():
         raise error.Abort(_('ssl connection failed'))
 
     sslsocket._hgstate = {
         'caloaded': caloaded,
         'hostname': serverhostname,
         'settings': settings,
         'ui': ui,
     }
 
     return sslsocket
 
 def wrapserversocket(sock, ui, certfile=None, keyfile=None, cafile=None,
                      requireclientcert=False):
     """Wrap a socket for use by servers.
 
     ``certfile`` and ``keyfile`` specify the files containing the certificate's
     public and private keys, respectively. Both keys can be defined in the same
     file via ``certfile`` (the private key must come first in the file).
 
     ``cafile`` defines the path to certificate authorities.
 
     ``requireclientcert`` specifies whether to require client certificates.
 
     Typically ``cafile`` is only defined if ``requireclientcert`` is true.
     """
+    protocol, options = protocolsettings('tls1.0')
+
+    # This config option is intended for use in tests only. It is a giant
+    # footgun to kill security. Don't define it.
+    exactprotocol = ui.config('devel', 'serverexactprotocol')
+    if exactprotocol == 'tls1.0':
+        protocol = ssl.PROTOCOL_TLSv1
+    elif exactprotocol == 'tls1.1':
+        protocol = ssl.PROTOCOL_TLSv1_1
+    elif exactprotocol == 'tls1.2':
+        protocol = ssl.PROTOCOL_TLSv1_2
+    elif exactprotocol:
+        raise error.Abort(_('invalid value for serverexactprotocol: %s') %
+                          exactprotocol)
+
     if modernssl:
         # We /could/ use create_default_context() here since it doesn't load
-        # CAs when configured for client auth.
-        sslcontext = SSLContext(ssl.PROTOCOL_SSLv23)
-        # SSLv2 and SSLv3 are broken. Ban them outright.
-        sslcontext.options |= OP_NO_SSLv2 | OP_NO_SSLv3
-        # Prevent CRIME
-        sslcontext.options |= getattr(ssl, 'OP_NO_COMPRESSION', 0)
+        # CAs when configured for client auth. However, it is hard-coded to
+        # use ssl.PROTOCOL_SSLv23 which may not be appropriate here.
+        sslcontext = SSLContext(protocol)
+        sslcontext.options |= options
+
         # Improve forward secrecy.
         sslcontext.options |= getattr(ssl, 'OP_SINGLE_DH_USE', 0)
         sslcontext.options |= getattr(ssl, 'OP_SINGLE_ECDH_USE', 0)
 
         # Use the list of more secure ciphers if found in the ssl module.
         if util.safehasattr(ssl, '_RESTRICTED_SERVER_CIPHERS'):
             sslcontext.options |= getattr(ssl, 'OP_CIPHER_SERVER_PREFERENCE', 0)
             sslcontext.set_ciphers(ssl._RESTRICTED_SERVER_CIPHERS)
     else:
         sslcontext = SSLContext(ssl.PROTOCOL_TLSv1)
 
     if requireclientcert:
         sslcontext.verify_mode = ssl.CERT_REQUIRED
     else:
         sslcontext.verify_mode = ssl.CERT_NONE
 
     if certfile or keyfile:
         sslcontext.load_cert_chain(certfile=certfile, keyfile=keyfile)
 
     if cafile:
         sslcontext.load_verify_locations(cafile=cafile)
 
     return sslcontext.wrap_socket(sock, server_side=True)
 
 class wildcarderror(Exception):
     """Represents an error parsing wildcards in DNS name."""
 
 def _dnsnamematch(dn, hostname, maxwildcards=1):
     """Match DNS names according RFC 6125 section 6.4.3.
 
     This code is effectively copied from CPython's ssl._dnsname_match.
 
     Returns a bool indicating whether the expected hostname matches
     the value in ``dn``.
     """
     pats = []
     if not dn:
         return False
 
     pieces = dn.split(r'.')
     leftmost = pieces[0]
     remainder = pieces[1:]
     wildcards = leftmost.count('*')
     if wildcards > maxwildcards:
         raise wildcarderror(
             _('too many wildcards in certificate DNS name: %s') % dn)
 
     # speed up common case w/o wildcards
     if not wildcards:
         return dn.lower() == hostname.lower()
 
     # RFC 6125, section 6.4.3, subitem 1.
     # The client SHOULD NOT attempt to match a presented identifier in which
     # the wildcard character comprises a label other than the left-most label.
     if leftmost == '*':
         # When '*' is a fragment by itself, it matches a non-empty dotless
         # fragment.
         pats.append('[^.]+')
     elif leftmost.startswith('xn--') or hostname.startswith('xn--'):
         # RFC 6125, section 6.4.3, subitem 3.
         # The client SHOULD NOT attempt to match a presented identifier
         # where the wildcard character is embedded within an A-label or
         # U-label of an internationalized domain name.
         pats.append(re.escape(leftmost))
     else:
         # Otherwise, '*' matches any dotless string, e.g. www*
         pats.append(re.escape(leftmost).replace(r'\*', '[^.]*'))
 
     # add the remaining fragments, ignore any wildcards
     for frag in remainder:
         pats.append(re.escape(frag))
 
     pat = re.compile(r'\A' + r'\.'.join(pats) + r'\Z', re.IGNORECASE)
     return pat.match(hostname) is not None
 
 def _verifycert(cert, hostname):
     '''Verify that cert (in socket.getpeercert() format) matches hostname.
     CRLs is not handled.
 
     Returns error message if any problems are found and None on success.
     '''
     if not cert:
         return _('no certificate received')
 
     dnsnames = []
     san = cert.get('subjectAltName', [])
     for key, value in san:
         if key == 'DNS':
             try:
                 if _dnsnamematch(value, hostname):
                     return
             except wildcarderror as e:
                 return e.args[0]
 
             dnsnames.append(value)
 
     if not dnsnames:
         # The subject is only checked when there is no DNS in subjectAltName.
         for sub in cert.get('subject', []):
             for key, value in sub:
                 # According to RFC 2818 the most specific Common Name must
                 # be used.
                 if key == 'commonName':
                     # 'subject' entries are unicide.
                     try:
                         value = value.encode('ascii')
                     except UnicodeEncodeError:
                         return _('IDN in certificate not supported')
 
                     try:
                         if _dnsnamematch(value, hostname):
                             return
                     except wildcarderror as e:
                         return e.args[0]
 
                     dnsnames.append(value)
 
     if len(dnsnames) > 1:
         return _('certificate is for %s') % ', '.join(dnsnames)
     elif len(dnsnames) == 1:
         return _('certificate is for %s') % dnsnames[0]
     else:
         return _('no commonName or subjectAltName found in certificate')
 
 def _plainapplepython():
     """return true if this seems to be a pure Apple Python that
     * is unfrozen and presumably has the whole mercurial module in the file
       system
     * presumably is an Apple Python that uses Apple OpenSSL which has patches
       for using system certificate store CAs in addition to the provided
       cacerts file
     """
     if sys.platform != 'darwin' or util.mainfrozen() or not sys.executable:
         return False
     exe = os.path.realpath(sys.executable).lower()
     return (exe.startswith('/usr/bin/python') or
             exe.startswith('/system/library/frameworks/python.framework/'))
 
 _systemcacertpaths = [
     # RHEL, CentOS, and Fedora
     '/etc/pki/tls/certs/ca-bundle.trust.crt',
     # Debian, Ubuntu, Gentoo
     '/etc/ssl/certs/ca-certificates.crt',
 ]
 
 def _defaultcacerts(ui):
     """return path to default CA certificates or None.
 
     It is assumed this function is called when the returned certificates
     file will actually be used to validate connections. Therefore this
     function may print warnings or debug messages assuming this usage.
 
     We don't print a message when the Python is able to load default
     CA certs because this scenario is detected at socket connect time.
     """
     # The "certifi" Python package provides certificates. If it is installed,
     # assume the user intends it to be used and use it.
     try:
         import certifi
         certs = certifi.where()
         ui.debug('using ca certificates from certifi\n')
         return certs
     except ImportError:
         pass
 
     # On Windows, only the modern ssl module is capable of loading the system
     # CA certificates. If we're not capable of doing that, emit a warning
     # because we'll get a certificate verification error later and the lack
     # of loaded CA certificates will be the reason why.
     # Assertion: this code is only called if certificates are being verified.
     if os.name == 'nt':
         if not _canloaddefaultcerts:
             ui.warn(_('(unable to load Windows CA certificates; see '
                       'https://mercurial-scm.org/wiki/SecureConnections for '
                       'how to configure Mercurial to avoid this message)\n'))
 
         return None
 
     # Apple's OpenSSL has patches that allow a specially constructed certificate
     # to load the system CA store. If we're running on Apple Python, use this
     # trick.
     if _plainapplepython():
         dummycert = os.path.join(os.path.dirname(__file__), 'dummycert.pem')
         if os.path.exists(dummycert):
             return dummycert
 
     # The Apple OpenSSL trick isn't available to us. If Python isn't able to
     # load system certs, we're out of luck.
     if sys.platform == 'darwin':
         # FUTURE Consider looking for Homebrew or MacPorts installed certs
         # files. Also consider exporting the keychain certs to a file during
         # Mercurial install.
         if not _canloaddefaultcerts:
             ui.warn(_('(unable to load CA certificates; see '
                       'https://mercurial-scm.org/wiki/SecureConnections for '
                       'how to configure Mercurial to avoid this message)\n'))
         return None
 
     # / is writable on Windows. Out of an abundance of caution make sure
     # we're not on Windows because paths from _systemcacerts could be installed
     # by non-admin users.
     assert os.name != 'nt'
 
     # Try to find CA certificates in well-known locations. We print a warning
     # when using a found file because we don't want too much silent magic
     # for security settings. The expectation is that proper Mercurial
     # installs will have the CA certs path defined at install time and the
     # installer/packager will make an appropriate decision on the user's
     # behalf. We only get here and perform this setting as a feature of
     # last resort.
     if not _canloaddefaultcerts:
         for path in _systemcacertpaths:
             if os.path.isfile(path):
                 ui.warn(_('(using CA certificates from %s; if you see this '
                           'message, your Mercurial install is not properly '
                           'configured; see '
                           'https://mercurial-scm.org/wiki/SecureConnections '
                           'for how to configure Mercurial to avoid this '
                           'message)\n') % path)
                 return path
 
         ui.warn(_('(unable to load CA certificates; see '
                   'https://mercurial-scm.org/wiki/SecureConnections for '
                   'how to configure Mercurial to avoid this message)\n'))
 
     return None
 
 def validatesocket(sock):
     """Validate a socket meets security requiremnets.
 
     The passed socket must have been created with ``wrapsocket()``.
     """
     host = sock._hgstate['hostname']
     ui = sock._hgstate['ui']
     settings = sock._hgstate['settings']
 
     try:
         peercert = sock.getpeercert(True)
         peercert2 = sock.getpeercert()
     except AttributeError:
         raise error.Abort(_('%s ssl connection error') % host)
 
     if not peercert:
         raise error.Abort(_('%s certificate error: '
                            'no certificate received') % host)
 
     if settings['disablecertverification']:
         # We don't print the certificate fingerprint because it shouldn't
         # be necessary: if the user requested certificate verification be
         # disabled, they presumably already saw a message about the inability
         # to verify the certificate and this message would have printed the
         # fingerprint. So printing the fingerprint here adds little to no
         # value.
         ui.warn(_('warning: connection security to %s is disabled per current '
                   'settings; communication is susceptible to eavesdropping '
                   'and tampering\n') % host)
         return
 
     # If a certificate fingerprint is pinned, use it and only it to
     # validate the remote cert.
     peerfingerprints = {
         'sha1': hashlib.sha1(peercert).hexdigest(),
         'sha256': hashlib.sha256(peercert).hexdigest(),
         'sha512': hashlib.sha512(peercert).hexdigest(),
     }
 
     def fmtfingerprint(s):
         return ':'.join([s[x:x + 2] for x in range(0, len(s), 2)])
 
     nicefingerprint = 'sha256:%s' % fmtfingerprint(peerfingerprints['sha256'])
 
     if settings['certfingerprints']:
         for hash, fingerprint in settings['certfingerprints']:
             if peerfingerprints[hash].lower() == fingerprint:
                 ui.debug('%s certificate matched fingerprint %s:%s\n' %
                          (host, hash, fmtfingerprint(fingerprint)))
                 return
 
         # Pinned fingerprint didn't match. This is a fatal error.
         if settings['legacyfingerprint']:
             section = 'hostfingerprint'
             nice = fmtfingerprint(peerfingerprints['sha1'])
         else:
             section = 'hostsecurity'
             nice = '%s:%s' % (hash, fmtfingerprint(peerfingerprints[hash]))
         raise error.Abort(_('certificate for %s has unexpected '
                             'fingerprint %s') % (host, nice),
                           hint=_('check %s configuration') % section)
 
     # Security is enabled but no CAs are loaded. We can't establish trust
     # for the cert so abort.
     if not sock._hgstate['caloaded']:
         raise error.Abort(
             _('unable to verify security of %s (no loaded CA certificates); '
               'refusing to connect') % host,
             hint=_('see https://mercurial-scm.org/wiki/SecureConnections for '
                    'how to configure Mercurial to avoid this error or set '
                    'hostsecurity.%s:fingerprints=%s to trust this server') %
                    (host, nicefingerprint))
 
     msg = _verifycert(peercert2, host)
     if msg:
         raise error.Abort(_('%s certificate error: %s') % (host, msg),
                          hint=_('set hostsecurity.%s:certfingerprints=%s '
                                 'config setting or use --insecure to connect '
                                 'insecurely') %
                               (host, nicefingerprint))

tests/test-https.t

@@ -1,435 +1,503
 #require serve ssl
 
 Proper https client requires the built-in ssl from Python 2.6.
 
 Make server certificates:
 
   $ CERTSDIR="$TESTDIR/sslcerts"
   $ cat "$CERTSDIR/priv.pem" "$CERTSDIR/pub.pem" >> server.pem
   $ PRIV=`pwd`/server.pem
   $ cat "$CERTSDIR/priv.pem" "$CERTSDIR/pub-not-yet.pem" > server-not-yet.pem
   $ cat "$CERTSDIR/priv.pem" "$CERTSDIR/pub-expired.pem" > server-expired.pem
 
   $ hg init test
   $ cd test
   $ echo foo>foo
   $ mkdir foo.d foo.d/bAr.hg.d foo.d/baR.d.hg
   $ echo foo>foo.d/foo
   $ echo bar>foo.d/bAr.hg.d/BaR
   $ echo bar>foo.d/baR.d.hg/bAR
   $ hg commit -A -m 1
   adding foo
   adding foo.d/bAr.hg.d/BaR
   adding foo.d/baR.d.hg/bAR
   adding foo.d/foo
   $ hg serve -p $HGPORT -d --pid-file=../hg0.pid --certificate=$PRIV
   $ cat ../hg0.pid >> $DAEMON_PIDS
 
 cacert not found
 
   $ hg in --config web.cacerts=no-such.pem https://localhost:$HGPORT/
   abort: could not find web.cacerts: no-such.pem
   [255]
 
 Test server address cannot be reused
 
 #if windows
   $ hg serve -p $HGPORT --certificate=$PRIV 2>&1
   abort: cannot start server at ':$HGPORT':
   [255]
 #else
   $ hg serve -p $HGPORT --certificate=$PRIV 2>&1
   abort: cannot start server at ':$HGPORT': Address already in use
   [255]
 #endif
   $ cd ..
 
 Our test cert is not signed by a trusted CA. It should fail to verify if
 we are able to load CA certs.
 
 #if sslcontext defaultcacerts no-defaultcacertsloaded
   $ hg clone https://localhost:$HGPORT/ copy-pull
   (an attempt was made to load CA certificates but none were loaded; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this error)
   abort: error: *certificate verify failed* (glob)
   [255]
 #endif
 
 #if no-sslcontext defaultcacerts
   $ hg clone https://localhost:$HGPORT/ copy-pull
   (using CA certificates from *; if you see this message, your Mercurial install is not properly configured; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this message) (glob) (?)
   abort: error: *certificate verify failed* (glob)
   [255]
 #endif
 
 #if no-sslcontext windows
   $ hg clone https://localhost:$HGPORT/ copy-pull
   (unable to load Windows CA certificates; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this message)
   abort: error: *certificate verify failed* (glob)
   [255]
 #endif
 
 #if no-sslcontext osx
   $ hg clone https://localhost:$HGPORT/ copy-pull
   (unable to load CA certificates; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this message)
   abort: localhost certificate error: no certificate received
   (set hostsecurity.localhost:certfingerprints=sha256:20:de:b3:ad:b4:cd:a5:42:f0:74:41:1c:a2:70:1e:da:6e:c0:5c:16:9e:e7:22:0f:f1:b7:e5:6e:e4:92:af:7e config setting or use --insecure to connect insecurely)
   [255]
 #endif
 
 #if defaultcacertsloaded
   $ hg clone https://localhost:$HGPORT/ copy-pull
   (using CA certificates from *; if you see this message, your Mercurial install is not properly configured; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this message) (glob) (?)
   abort: error: *certificate verify failed* (glob)
   [255]
 #endif
 
 #if no-defaultcacerts
   $ hg clone https://localhost:$HGPORT/ copy-pull
   (unable to load * certificates; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this message) (glob) (?)
   abort: localhost certificate error: no certificate received
   (set hostsecurity.localhost:certfingerprints=sha256:20:de:b3:ad:b4:cd:a5:42:f0:74:41:1c:a2:70:1e:da:6e:c0:5c:16:9e:e7:22:0f:f1:b7:e5:6e:e4:92:af:7e config setting or use --insecure to connect insecurely)
   [255]
 #endif
 
 Specifying a per-host certificate file that doesn't exist will abort
 
   $ hg --config hostsecurity.localhost:verifycertsfile=/does/not/exist clone https://localhost:$HGPORT/
   abort: path specified by hostsecurity.localhost:verifycertsfile does not exist: /does/not/exist
   [255]
 
 A malformed per-host certificate file will raise an error
 
   $ echo baddata > badca.pem
 #if sslcontext
   $ hg --config hostsecurity.localhost:verifycertsfile=badca.pem clone https://localhost:$HGPORT/
   abort: error loading CA file badca.pem: * (glob)
   (file is empty or malformed?)
   [255]
 #else
   $ hg --config hostsecurity.localhost:verifycertsfile=badca.pem clone https://localhost:$HGPORT/
   abort: error: * (glob)
   [255]
 #endif
 
 A per-host certificate mismatching the server will fail verification
 
 (modern ssl is able to discern whether the loaded cert is a CA cert)
 #if sslcontext
   $ hg --config hostsecurity.localhost:verifycertsfile="$CERTSDIR/client-cert.pem" clone https://localhost:$HGPORT/
   (an attempt was made to load CA certificates but none were loaded; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this error)
   abort: error: *certificate verify failed* (glob)
   [255]
 #else
   $ hg --config hostsecurity.localhost:verifycertsfile="$CERTSDIR/client-cert.pem" clone https://localhost:$HGPORT/
   abort: error: *certificate verify failed* (glob)
   [255]
 #endif
 
 A per-host certificate matching the server's cert will be accepted
 
   $ hg --config hostsecurity.localhost:verifycertsfile="$CERTSDIR/pub.pem" clone -U https://localhost:$HGPORT/ perhostgood1
   requesting all changes
   adding changesets
   adding manifests
   adding file changes
   added 1 changesets with 4 changes to 4 files
 
 A per-host certificate with multiple certs and one matching will be accepted
 
   $ cat "$CERTSDIR/client-cert.pem" "$CERTSDIR/pub.pem" > perhost.pem
   $ hg --config hostsecurity.localhost:verifycertsfile=perhost.pem clone -U https://localhost:$HGPORT/ perhostgood2
   requesting all changes
   adding changesets
   adding manifests
   adding file changes
   added 1 changesets with 4 changes to 4 files
 
 Defining both per-host certificate and a fingerprint will print a warning
 
   $ hg --config hostsecurity.localhost:verifycertsfile="$CERTSDIR/pub.pem" --config hostsecurity.localhost:fingerprints=sha1:ecd87cd6b386d04fc1b8b41c9d8f5e168eef1c03 clone -U https://localhost:$HGPORT/ caandfingerwarning
   (hostsecurity.localhost:verifycertsfile ignored when host fingerprints defined; using host fingerprints for verification)
   requesting all changes
   adding changesets
   adding manifests
   adding file changes
   added 1 changesets with 4 changes to 4 files
 
   $ DISABLECACERTS="--config devel.disableloaddefaultcerts=true"
 
 Inability to verify peer certificate will result in abort
 
   $ hg clone https://localhost:$HGPORT/ copy-pull $DISABLECACERTS
   abort: unable to verify security of localhost (no loaded CA certificates); refusing to connect
   (see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this error or set hostsecurity.localhost:fingerprints=sha256:20:de:b3:ad:b4:cd:a5:42:f0:74:41:1c:a2:70:1e:da:6e:c0:5c:16:9e:e7:22:0f:f1:b7:e5:6e:e4:92:af:7e to trust this server)
   [255]
 
   $ hg clone --insecure https://localhost:$HGPORT/ copy-pull
   warning: connection security to localhost is disabled per current settings; communication is susceptible to eavesdropping and tampering
   requesting all changes
   adding changesets
   adding manifests
   adding file changes
   added 1 changesets with 4 changes to 4 files
   updating to branch default
   4 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg verify -R copy-pull
   checking changesets
   checking manifests
   crosschecking files in changesets and manifests
   checking files
   4 files, 1 changesets, 4 total revisions
   $ cd test
   $ echo bar > bar
   $ hg commit -A -d '1 0' -m 2
   adding bar
   $ cd ..
 
 pull without cacert
 
   $ cd copy-pull
   $ echo '[hooks]' >> .hg/hgrc
   $ echo "changegroup = printenv.py changegroup" >> .hg/hgrc
   $ hg pull $DISABLECACERTS
   pulling from https://localhost:$HGPORT/
   abort: unable to verify security of localhost (no loaded CA certificates); refusing to connect
   (see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this error or set hostsecurity.localhost:fingerprints=sha256:20:de:b3:ad:b4:cd:a5:42:f0:74:41:1c:a2:70:1e:da:6e:c0:5c:16:9e:e7:22:0f:f1:b7:e5:6e:e4:92:af:7e to trust this server)
   [255]
 
   $ hg pull --insecure
   pulling from https://localhost:$HGPORT/
   warning: connection security to localhost is disabled per current settings; communication is susceptible to eavesdropping and tampering
   searching for changes
   adding changesets
   adding manifests
   adding file changes
   added 1 changesets with 1 changes to 1 files
   changegroup hook: HG_NODE=5fed3813f7f5e1824344fdc9cf8f63bb662c292d HG_NODE_LAST=5fed3813f7f5e1824344fdc9cf8f63bb662c292d HG_SOURCE=pull HG_TXNID=TXN:* HG_URL=https://localhost:$HGPORT/ (glob)
   (run 'hg update' to get a working copy)
   $ cd ..
 
 cacert configured in local repo
 
   $ cp copy-pull/.hg/hgrc copy-pull/.hg/hgrc.bu
   $ echo "[web]" >> copy-pull/.hg/hgrc
   $ echo "cacerts=$CERTSDIR/pub.pem" >> copy-pull/.hg/hgrc
   $ hg -R copy-pull pull --traceback
   pulling from https://localhost:$HGPORT/
   searching for changes
   no changes found
   $ mv copy-pull/.hg/hgrc.bu copy-pull/.hg/hgrc
 
 cacert configured globally, also testing expansion of environment
 variables in the filename
 
   $ echo "[web]" >> $HGRCPATH
   $ echo 'cacerts=$P/pub.pem' >> $HGRCPATH
   $ P="$CERTSDIR" hg -R copy-pull pull
   pulling from https://localhost:$HGPORT/
   searching for changes
   no changes found
   $ P="$CERTSDIR" hg -R copy-pull pull --insecure
   pulling from https://localhost:$HGPORT/
   warning: connection security to localhost is disabled per current settings; communication is susceptible to eavesdropping and tampering
   searching for changes
   no changes found
 
 empty cacert file
 
   $ touch emptycafile
 
 #if sslcontext
   $ hg --config web.cacerts=emptycafile -R copy-pull pull
   pulling from https://localhost:$HGPORT/
   abort: error loading CA file emptycafile: * (glob)
   (file is empty or malformed?)
   [255]
 #else
   $ hg --config web.cacerts=emptycafile -R copy-pull pull
   pulling from https://localhost:$HGPORT/
   abort: error: * (glob)
   [255]
 #endif
 
 cacert mismatch
 
   $ hg -R copy-pull pull --config web.cacerts="$CERTSDIR/pub.pem" \
   > https://127.0.0.1:$HGPORT/
   pulling from https://127.0.0.1:$HGPORT/ (glob)
   abort: 127.0.0.1 certificate error: certificate is for localhost (glob)
   (set hostsecurity.127.0.0.1:certfingerprints=sha256:20:de:b3:ad:b4:cd:a5:42:f0:74:41:1c:a2:70:1e:da:6e:c0:5c:16:9e:e7:22:0f:f1:b7:e5:6e:e4:92:af:7e config setting or use --insecure to connect insecurely) (glob)
   [255]
   $ hg -R copy-pull pull --config web.cacerts="$CERTSDIR/pub.pem" \
   > https://127.0.0.1:$HGPORT/ --insecure
   pulling from https://127.0.0.1:$HGPORT/ (glob)
   warning: connection security to 127.0.0.1 is disabled per current settings; communication is susceptible to eavesdropping and tampering (glob)
   searching for changes
   no changes found
   $ hg -R copy-pull pull --config web.cacerts="$CERTSDIR/pub-other.pem"
   pulling from https://localhost:$HGPORT/
   abort: error: *certificate verify failed* (glob)
   [255]
   $ hg -R copy-pull pull --config web.cacerts="$CERTSDIR/pub-other.pem" \
   > --insecure
   pulling from https://localhost:$HGPORT/
   warning: connection security to localhost is disabled per current settings; communication is susceptible to eavesdropping and tampering
   searching for changes
   no changes found
 
 Test server cert which isn't valid yet
 
   $ hg serve -R test -p $HGPORT1 -d --pid-file=hg1.pid --certificate=server-not-yet.pem
   $ cat hg1.pid >> $DAEMON_PIDS
   $ hg -R copy-pull pull --config web.cacerts="$CERTSDIR/pub-not-yet.pem" \
   > https://localhost:$HGPORT1/
   pulling from https://localhost:$HGPORT1/
   abort: error: *certificate verify failed* (glob)
   [255]
 
 Test server cert which no longer is valid
 
   $ hg serve -R test -p $HGPORT2 -d --pid-file=hg2.pid --certificate=server-expired.pem
   $ cat hg2.pid >> $DAEMON_PIDS
   $ hg -R copy-pull pull --config web.cacerts="$CERTSDIR/pub-expired.pem" \
   > https://localhost:$HGPORT2/
   pulling from https://localhost:$HGPORT2/
   abort: error: *certificate verify failed* (glob)
   [255]
 
 Fingerprints
 
 - works without cacerts (hostkeyfingerprints)
   $ hg -R copy-pull id https://localhost:$HGPORT/ --insecure --config hostfingerprints.localhost=ec:d8:7c:d6:b3:86:d0:4f:c1:b8:b4:1c:9d:8f:5e:16:8e:ef:1c:03
   5fed3813f7f5
 
 - works without cacerts (hostsecurity)
   $ hg -R copy-pull id https://localhost:$HGPORT/ --config hostsecurity.localhost:fingerprints=sha1:ecd87cd6b386d04fc1b8b41c9d8f5e168eef1c03
   5fed3813f7f5
 
   $ hg -R copy-pull id https://localhost:$HGPORT/ --config hostsecurity.localhost:fingerprints=sha256:20:de:b3:ad:b4:cd:a5:42:f0:74:41:1c:a2:70:1e:da:6e:c0:5c:16:9e:e7:22:0f:f1:b7:e5:6e:e4:92:af:7e
   5fed3813f7f5
 
 - multiple fingerprints specified and first matches
   $ hg --config 'hostfingerprints.localhost=ecd87cd6b386d04fc1b8b41c9d8f5e168eef1c03, deadbeefdeadbeefdeadbeefdeadbeefdeadbeef' -R copy-pull id https://localhost:$HGPORT/ --insecure
   5fed3813f7f5
 
   $ hg --config 'hostsecurity.localhost:fingerprints=sha1:ecd87cd6b386d04fc1b8b41c9d8f5e168eef1c03, sha1:deadbeefdeadbeefdeadbeefdeadbeefdeadbeef' -R copy-pull id https://localhost:$HGPORT/
   5fed3813f7f5
 
 - multiple fingerprints specified and last matches
   $ hg --config 'hostfingerprints.localhost=deadbeefdeadbeefdeadbeefdeadbeefdeadbeef, ecd87cd6b386d04fc1b8b41c9d8f5e168eef1c03' -R copy-pull id https://localhost:$HGPORT/ --insecure
   5fed3813f7f5
 
   $ hg --config 'hostsecurity.localhost:fingerprints=sha1:deadbeefdeadbeefdeadbeefdeadbeefdeadbeef, sha1:ecd87cd6b386d04fc1b8b41c9d8f5e168eef1c03' -R copy-pull id https://localhost:$HGPORT/
   5fed3813f7f5
 
 - multiple fingerprints specified and none match
 
   $ hg --config 'hostfingerprints.localhost=deadbeefdeadbeefdeadbeefdeadbeefdeadbeef, aeadbeefdeadbeefdeadbeefdeadbeefdeadbeef' -R copy-pull id https://localhost:$HGPORT/ --insecure
   abort: certificate for localhost has unexpected fingerprint ec:d8:7c:d6:b3:86:d0:4f:c1:b8:b4:1c:9d:8f:5e:16:8e:ef:1c:03
   (check hostfingerprint configuration)
   [255]
 
   $ hg --config 'hostsecurity.localhost:fingerprints=sha1:deadbeefdeadbeefdeadbeefdeadbeefdeadbeef, sha1:aeadbeefdeadbeefdeadbeefdeadbeefdeadbeef' -R copy-pull id https://localhost:$HGPORT/
   abort: certificate for localhost has unexpected fingerprint sha1:ec:d8:7c:d6:b3:86:d0:4f:c1:b8:b4:1c:9d:8f:5e:16:8e:ef:1c:03
   (check hostsecurity configuration)
   [255]
 
 - fails when cert doesn't match hostname (port is ignored)
   $ hg -R copy-pull id https://localhost:$HGPORT1/ --config hostfingerprints.localhost=ecd87cd6b386d04fc1b8b41c9d8f5e168eef1c03
   abort: certificate for localhost has unexpected fingerprint f4:2f:5a:0c:3e:52:5b:db:e7:24:a8:32:1d:18:97:6d:69:b5:87:84
   (check hostfingerprint configuration)
   [255]
 
 
 - ignores that certificate doesn't match hostname
   $ hg -R copy-pull id https://127.0.0.1:$HGPORT/ --config hostfingerprints.127.0.0.1=ecd87cd6b386d04fc1b8b41c9d8f5e168eef1c03
   5fed3813f7f5
 
-HGPORT1 is reused below for tinyproxy tests. Kill that server.
+Ports used by next test. Kill servers.
+
+  $ killdaemons.py hg0.pid
   $ killdaemons.py hg1.pid
+  $ killdaemons.py hg2.pid
+
+#if sslcontext
+Start servers running supported TLS versions
+
+  $ cd test
+  $ hg serve -p $HGPORT -d --pid-file=../hg0.pid --certificate=$PRIV \
+  > --config devel.serverexactprotocol=tls1.0
+  $ cat ../hg0.pid >> $DAEMON_PIDS
+  $ hg serve -p $HGPORT1 -d --pid-file=../hg1.pid --certificate=$PRIV \
+  > --config devel.serverexactprotocol=tls1.1
+  $ cat ../hg1.pid >> $DAEMON_PIDS
+  $ hg serve -p $HGPORT2 -d --pid-file=../hg2.pid --certificate=$PRIV \
+  > --config devel.serverexactprotocol=tls1.2
+  $ cat ../hg2.pid >> $DAEMON_PIDS
+  $ cd ..
+
+Clients talking same TLS versions work
+
+  $ P="$CERTSDIR" hg --config hostsecurity.minimumprotocol=tls1.0 id https://localhost:$HGPORT/
+  5fed3813f7f5
+  $ P="$CERTSDIR" hg --config hostsecurity.minimumprotocol=tls1.1 id https://localhost:$HGPORT1/
+  5fed3813f7f5
+  $ P="$CERTSDIR" hg --config hostsecurity.minimumprotocol=tls1.2 id https://localhost:$HGPORT2/
+  5fed3813f7f5
+
+Clients requiring newer TLS version than what server supports fail
+
+  $ P="$CERTSDIR" hg --config hostsecurity.minimumprotocol=tls1.1 id https://localhost:$HGPORT/
+  (could not negotiate a common protocol; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this error)
+  abort: error: *unsupported protocol* (glob)
+  [255]
+  $ P="$CERTSDIR" hg --config hostsecurity.minimumprotocol=tls1.2 id https://localhost:$HGPORT/
+  (could not negotiate a common protocol; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this error)
+  abort: error: *unsupported protocol* (glob)
+  [255]
+  $ P="$CERTSDIR" hg --config hostsecurity.minimumprotocol=tls1.2 id https://localhost:$HGPORT1/
+  (could not negotiate a common protocol; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this error)
+  abort: error: *unsupported protocol* (glob)
+  [255]
+
+The per-host config option overrides the default
+
+  $ P="$CERTSDIR" hg id https://localhost:$HGPORT/ \
+  > --config hostsecurity.minimumprotocol=tls1.2 \
+  > --config hostsecurity.localhost:minimumprotocol=tls1.0
+  5fed3813f7f5
+
+The per-host config option by itself works
+
+  $ P="$CERTSDIR" hg id https://localhost:$HGPORT/ \
+  > --config hostsecurity.localhost:minimumprotocol=tls1.2
+  (could not negotiate a common protocol; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this error)
+  abort: error: *unsupported protocol* (glob)
+  [255]
+
+  $ killdaemons.py hg0.pid
+  $ killdaemons.py hg1.pid
+  $ killdaemons.py hg2.pid
+#endif
 
 Prepare for connecting through proxy
 
+  $ hg serve -R test -p $HGPORT -d --pid-file=hg0.pid --certificate=$PRIV
+  $ cat hg0.pid >> $DAEMON_PIDS
+  $ hg serve -R test -p $HGPORT2 -d --pid-file=hg2.pid --certificate=server-expired.pem
+  $ cat hg2.pid >> $DAEMON_PIDS
+tinyproxy.py doesn't fully detach, so killing it may result in extra output
+from the shell. So don't kill it.
   $ tinyproxy.py $HGPORT1 localhost >proxy.log </dev/null 2>&1 &
   $ while [ ! -f proxy.pid ]; do sleep 0; done
   $ cat proxy.pid >> $DAEMON_PIDS
 
   $ echo "[http_proxy]" >> copy-pull/.hg/hgrc
   $ echo "always=True" >> copy-pull/.hg/hgrc
   $ echo "[hostfingerprints]" >> copy-pull/.hg/hgrc
   $ echo "localhost =" >> copy-pull/.hg/hgrc
 
 Test unvalidated https through proxy
 
   $ http_proxy=http://localhost:$HGPORT1/ hg -R copy-pull pull --insecure --traceback
   pulling from https://localhost:$HGPORT/
   warning: connection security to localhost is disabled per current settings; communication is susceptible to eavesdropping and tampering
   searching for changes
   no changes found
 
 Test https with cacert and fingerprint through proxy
 
   $ http_proxy=http://localhost:$HGPORT1/ hg -R copy-pull pull \
   > --config web.cacerts="$CERTSDIR/pub.pem"
   pulling from https://localhost:$HGPORT/
   searching for changes
   no changes found
   $ http_proxy=http://localhost:$HGPORT1/ hg -R copy-pull pull https://127.0.0.1:$HGPORT/ --config hostfingerprints.127.0.0.1=ecd87cd6b386d04fc1b8b41c9d8f5e168eef1c03
   pulling from https://127.0.0.1:$HGPORT/ (glob)
   searching for changes
   no changes found
 
 Test https with cert problems through proxy
 
   $ http_proxy=http://localhost:$HGPORT1/ hg -R copy-pull pull \
   > --config web.cacerts="$CERTSDIR/pub-other.pem"
   pulling from https://localhost:$HGPORT/
   abort: error: *certificate verify failed* (glob)
   [255]
   $ http_proxy=http://localhost:$HGPORT1/ hg -R copy-pull pull \
   > --config web.cacerts="$CERTSDIR/pub-expired.pem" https://localhost:$HGPORT2/
   pulling from https://localhost:$HGPORT2/
   abort: error: *certificate verify failed* (glob)
   [255]
 
 
   $ killdaemons.py hg0.pid
 
 #if sslcontext
 
 Start hgweb that requires client certificates:
 
   $ cd test
   $ hg serve -p $HGPORT -d --pid-file=../hg0.pid --certificate=$PRIV \
   > --config devel.servercafile=$PRIV --config devel.serverrequirecert=true
   $ cat ../hg0.pid >> $DAEMON_PIDS
   $ cd ..
 
 without client certificate:
 
   $ P="$CERTSDIR" hg id https://localhost:$HGPORT/
   abort: error: *handshake failure* (glob)
   [255]
 
 with client certificate:
 
   $ cat << EOT >> $HGRCPATH
   > [auth]
   > l.prefix = localhost
   > l.cert = $CERTSDIR/client-cert.pem
   > l.key = $CERTSDIR/client-key.pem
   > EOT
 
   $ P="$CERTSDIR" hg id https://localhost:$HGPORT/ \
   > --config auth.l.key="$CERTSDIR/client-key-decrypted.pem"
   5fed3813f7f5
 
   $ printf '1234\n' | env P="$CERTSDIR" hg id https://localhost:$HGPORT/ \
   > --config ui.interactive=True --config ui.nontty=True
   passphrase for */client-key.pem: 5fed3813f7f5 (glob)
 
   $ env P="$CERTSDIR" hg id https://localhost:$HGPORT/
   abort: error: * (glob)
   [255]
 
 #endif