#45 Added hg keyring_clear

README.txt

@@ -1,279 +1,316 b''
 .. -*- mode: rst; compile-command: "rst2html README.txt README.html" -*-
 
-=================
+=======================================================
 Mercurial Keyring
-=================
+=======================================================
 
 Mercurial Keyring is a Mercurial_ extension used to securely save HTTP
 and SMTP authentication passwords in password databases (Gnome
 Keyring, KDE KWallet, OSXKeyChain, Windows Vault etc).
 
 With ``mercurial_keyring`` active, Mercurial remembers your passwords
 and reuses them without prompting (as if you stored them in ``.hgrc``),
 but password storage is reasonably secure.
 
 Actual password storage is implemented by the keyring_ library, this 
 extension glues it to Mercurial.
 
 .. contents::
    :local:
    :depth: 2
 
 .. sectnum::
 
 .. _keyring: http://pypi.python.org/pypi/keyring
 .. _Mercurial: http://mercurial.selenic.com
 
 How does it work
-================
+=======================================================
 
 On your first pull or push to HTTP url (or first email sent via given
 SMTP server), you are prompted for the password, just like bare
 Mercurial does. But the password you entered is saved to appropriate
 password database. On successive runs, whenever the password is
 needed, ``mercurial_keyring`` checks for password in password
 database, and uses it without troubling you.
 
 In case password turns out to be incorrect (for example, because you
-changed it, or entered it incorrectly), ``mercurial_keyring`` wipes
-it, and prompts you again.
+changed it, or entered it incorrectly), ``mercurial_keyring`` prompts
+you again, and overwrites the password.
 
 You can use many passwords (for various remote urls).  Saved passwords
 are identified by pair of username and url prefix. See below for
 information how to configure those properly.
 
 Installation
-============
+=======================================================
 
 Prerequisites
 -------------
 
 This extension requires keyring_ and `mercurial_extension_utils`_ to
 work. In many cases both will be installed automatically while you
 install ``mercurial_keyring``, but you may need to control the process.
 
 The keyring_ library can usually be installed by::
 
     pip install --user keyring
 
 (or ``easy_install keyring``), but on some systems it is preferable to
 use official distribution archive. For example, on Debian and Ubuntu,
 you may install ``python-keyring`` and either ``python-keyring-gnome``
 or ``python-keyring-kwallet`` packages::
 
     sudo apt-get install python-keyring python-keyring-gnome
 
 (this will save you the need to provide working compiler and various
 development libraries).
 
 The `mercurial_extension_utils`_ module is tiny Python-only module,
 which can be installed by::
 
     pip install --user mercurial_extension_utils
 
 but in some cases (Windows…) require more care. See
 `mercurial_extension_utils`_ documentation.
     
 
 Extension installation
 ----------------------
 
 There are two possible ways of installing the extension: using PyPi package,
 or using source clone.
 
 To install as a package::
 
     pip install --user mercurial_keyring
 
 (or ``sudo pip install mercurial_keyring`` for system-wide
 installation) and then enable it in ``~/.hgrc`` (or
 ``/etc/mercurial/hgrc`` or ``Mercurial.ini``) using::
 
     [extensions]
     mercurial_keyring = 
 
 To install as source clone, install keyring_ according to instructions above, then
 clone::
     
     hg clone https://bitbucket.org/Mekk/mercurial_keyring/
     hg clone https://bitbucket.org/Mekk/mercurial-extension_utils/
 
 and configure Mercurial by telling it full path to the extension
 (in )::
 
     [extensions]
     mercurial_keyring = /path/to/mercurial_keyring/mercurial_keyring.py
 
 .. _the code: 
 .. _mercurial_keyring.py: http://bitbucket.org/Mekk/mercurial_keyring/src/tip/mercurial_keyring.py
 
 Password backend configuration
-==============================
+=======================================================
 
 The library should usually pick the most appropriate password backend
 without configuration. Still, if necessary, it can be configured using
 ``keyringrc.cfg`` file.  Refer to keyring_ docs for more details.
 
 .. note::
 
    With current (as I write) keyring (5.6), this file is (on Linux)
    located at ``~/.local/share/python_keyring/keyringrc.cfg`` and
    it's example content look like::
 
         [backend]
         default-keyring=keyring.backends.Gnome.Keyring
         # default-keyring=keyring.backends.kwallet.Keyring
 
    For list of known backends run ``pydoc keyring.backends``.
 
 
 ``hgrc`` configuration (HTTP)
-===============================
+=======================================================
 
 Mercurial Keyring uses standard Mercurial ``[auth]`` configuration to
 detect your username (on given remote) and url prefix. You are
 strongly advised to configure both.
 
 Without the username ``mercurial_keyring`` can't save or restore
 passwords, so it disables itself.
 
 Without url prefix ``mercurial_keyring`` works, but binds passwords to
 repository urls. That means you will have to (re)enter password for
 every repository cloned from given remote (and that there will be many
 copies of this password in secure storage).
 
 Repository level configuration
 ------------------------------------
 
 Edit repository-local ``.hg/hgrc`` and save there the remote
 repository path and the username, but do not save the password. For
 example:
 
 ::
 
     [paths]
     myremote = https://my.server.com/hgrepo/someproject
 
     [auth]
     myremote.prefix = https://my.server.com/hgrepo
     myremote.username = John
 
 Simpler form with url-embedded name can also be used:
 
 ::
 
     [paths]
     bitbucket = https://[e-mail]/hgrepo/someproject/
 
 Note that all repositories sharing the same ``prefix`` share the same
 password.
 
 Mercurial allows also for password in ``.hg/hgrc`` (either given by
 ``«prefix».password``, or embedded in url). If such password is found,
 Mercurial Keyring disables itself.
 
 
 Account-level configuration
 ---------------------------
 
 If you are consistent about remote repository nicknames, you can
 configure the username in your `~/.hgrc` (`.hgrc` in your home
 directory). For example, write there::
 
     [auth]
     acme.prefix = hg.acme.com/repositories
     acme.username = johnny
     acme.schemes = http https
     bitbucket.prefix = https://bitbucket.org
     bitbucket.username = Mekk
     mydep.prefix = https://dev.acmeorg.com
     mydep.username = drmartin
 
 and as long as you will be using alias ``acme`` for repositories like
 ``https://hg.acme.com/repositories/my_beautiful_app``, username
 ``johnny`` will be used, and the same password reused. Similarly
 any ``hg push bitbucket`` will share the same password.
 
 With such config repository-level ``.hg/hgrc`` need only contain
 ``[paths]``.
 
 Additional advantage of this method is that it works also during
 `clone`.
 
 
 .. note::
 
    Mercurial Keyring works well with `Path Pattern`_. On my setup I use::
 
        [path_pattern]
        bitbucket.local = ~/devel/{below}
        bitbucket.remote = https://bitbucket.org/Mekk/{below:/=-}
  
    so all my repositories understand ``hg push bitbucket`` without
    any repository-level configuration.
 
 
 ``hgrc`` configuration (SMTP)
-===============================
+=======================================================
 
 Edit either repository-local ``.hg/hgrc``, or ``~/.hgrc`` and set
 there all standard email and smtp properties, including SMTP
 username, but without SMTP password. For example:
 
 ::
 
     [email]
     method = smtp
     from = Joe Doe <[e-mail]>
 
     [smtp]
     host = smtp.gmail.com
     port = 587
     username = [e-mail]
     tls = true
 
 Just as in case of HTTP, you *must* set username, but *must not* set
 password here to use the extension, in other cases it will revert to
 the default behavior.
 
 Usage
-=====
+======================================================
+
+Saving and restoring passwords
+-------------------------------------------------------
 
 Configure the repository as above, then just ``hg pull``, ``hg push``,
 etc.  You should be asked for the password only once (per every
 username and remote repository prefix or url combination).
 
 Similarly, for email, configure as above and just ``hg email``.
 Again, you will be asked for the password once (per every username and
 email server address combination).
 
+Checking password status (``hg keyring_check``)
+-------------------------------------------------------
+
+The ``keyring_check`` command can be used to check whether/which
+password(s) are saved. It can be used in three ways:
+
+- without parameters, it prints info related to all HTTP paths
+  defined for current repository (everything from ``hg paths``
+  that resolves to HTTP url)::
+
+    hg keyring_check
+
+- given alias as param, it prints info about this alias::
+
+    hg keyring_check work
+
+- finally, any path can be checked::
+
+    hg keyring_check https://bitbucket.org/Mekk/mercurial_keyring
+
+Deleting saved password (``hg keyring_clear``)
+-------------------------------------------------------
+
+The ``keyring_clear`` command removes saved password related to given
+path. It can be used in two ways:
+
+- given alias as param, it drops password used by this alias::
+
+    hg keyring_clear work
+
+- given full path, it drops password related to this path::
+
+    hg keyring_clear https://bitbucket.org/Mekk/mercurial_keyring
+
 Implementation details
-======================
+=======================================================
 
 The extension is monkey-patching the mercurial ``passwordmgr`` class
 to replace the ``find_user_password`` method. Detailed order of operations
 is described in the comments inside `the code`_.
 
 History
-==========
+=======================================================
 
 See `HISTORY.txt`_.
 
 Development
-===========
+=======================================================
 
 Development is tracked on BitBucket, see 
 http://bitbucket.org/Mekk/mercurial_keyring/
 
 
 Additional notes
-================
+=======================================================
 
 Information about this extension is also available
 on Mercurial Wiki: http://mercurial.selenic.com/wiki/KeyringExtension
 
 .. _HISTORY.txt: http://bitbucket.org/Mekk/mercurial_keyring/src/tip/HISTORY.txt
 .. _TortoiseHg: http://tortoisehg.bitbucket.org/
 .. _Mercurial: http://mercurial.selenic.com
 .. _mercurial_extension_utils: https://bitbucket.org/Mekk/mercurial-extension_utils/
 .. _Path Pattern: https://bitbucket.org/Mekk/mercurial-path_pattern/

mercurial_keyring.py

@@ -1,740 +1,771 b''
 # -*- coding: utf-8 -*-
 #
 # mercurial_keyring: save passwords in password database
 #
 # Copyright (c) 2009 Marcin Kasperski <[e-mail]>
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions
 # are met:
 # 1. Redistributions of source code must retain the above copyright
 #    notice, this list of conditions and the following disclaimer.
 # 2. Redistributions in binary form must reproduce the above copyright
 #    notice, this list of conditions and the following disclaimer in the
 #    documentation and/or other materials provided with the distribution.
 # 3. The name of the author may not be used to endorse or promote products
 #    derived from this software without specific prior written permission.
 #
 # THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 # IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 # OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 # IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 # NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 # THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #
 # See README.txt for more details.
 
 '''securely save HTTP and SMTP passwords to encrypted storage
 
 mercurial_keyring securely saves HTTP and SMTP passwords in password
 databases (Gnome Keyring, KDE KWallet, OSXKeyChain, Win32 crypto
 services).
 
 The process is automatic.  Whenever bare Mercurial just prompts for
 the password, Mercurial with mercurial_keyring enabled checks whether
 saved password is available first.  If so, it is used.  If not, you
 will be prompted for the password, but entered password will be
 saved for the future use.
 
 In case saved password turns out to be invalid (HTTP or SMTP login
 fails) it is dropped, and you are asked for current password.
 
 Actual password storage is implemented by Python keyring library, this
 extension glues those services to Mercurial. Consult keyring
 documentation for information how to configure actual password
 backend (by default keyring guesses, usually correctly, for example
 you get KDE Wallet under KDE, and Gnome Keyring under Gnome or Unity).
 '''
 
 from mercurial import util, sslutil
 from mercurial.i18n import _
 from mercurial.url import passwordmgr
 from mercurial import mail
 from mercurial.mail import SMTPS, STARTTLS
 from mercurial import encoding
 
 from urlparse import urlparse
 import urllib2
 import smtplib
 import socket
 import os
 import sys
+import re
 
 # pylint: disable=invalid-name, line-too-long, protected-access, too-many-arguments
 
 ###########################################################################
 # Specific import trickery
 ###########################################################################
 
 
 def import_meu():
     """
     Convoluted import of mercurial_extension_utils, which helps
     TortoiseHg/Win setups. This routine and it's use below
     performs equivalent of
         from mercurial_extension_utils import monkeypatch_method
     but looks for some non-path directories.
     """
     try:
         import mercurial_extension_utils
     except ImportError:
         my_dir = os.path.dirname(__file__)
         sys.path.extend([
             # In the same dir (manual or site-packages after pip)
             my_dir,
             # Developer clone
             os.path.join(os.path.dirname(my_dir), "extension_utils"),
             # Side clone
             os.path.join(os.path.dirname(my_dir), "mercurial-extension_utils"),
         ])
         try:
             import mercurial_extension_utils
         except ImportError:
             raise util.Abort(_("""Can not import mercurial_extension_utils.
 Please install this module in Python path.
 See Installation chapter in https://bitbucket.org/Mekk/mercurial-dynamic_username/ for details
 (and for info about TortoiseHG on Windows, or other bundled Python)."""))
     return mercurial_extension_utils
 
 meu = import_meu()
 monkeypatch_method = meu.monkeypatch_method
 
 
 def import_keyring():
     """
     Importing keyring happens to be costly if wallet is slow, so we delay it
     until it is really needed. The routine below also works around various
     demandimport-related problems.
     """
     if 'keyring' in sys.modules:
         return sys.modules['keyring']
     # mercurial.demandimport incompatibility workaround.
     # various keyring backends fail as they can't properly import helper
     # modules (as demandimport modifies python import behaviour).
     # If you get import errors with demandimport in backtrace, try
     # guessing what to block and extending the list below.
     from mercurial import demandimport
     for blocked_module in [
             "gobject._gobject",
             "configparser",
             "json",
             "abc",
             "io",
             "keyring",
             "gdata.docs.service",
             "gdata.service",
             "types",
             "atom.http",
             "atom.http_interface",
             "atom.service",
             "atom.token_store",
             "ctypes",
             "secretstorage.exceptions",
             "fs.opener",
     ]:
         if blocked_module not in demandimport.ignore:
             demandimport.ignore.append(blocked_module)
 
     # Various attempts to define is_demandimport_enabled
     try:
         # Since Mercurial 2.9.1
         is_demandimport_enabled = demandimport.isenabled
     except AttributeError:
         def is_demandimport_enabled():
             """Checks whether demandimport is enabled at the moment"""
             return __import__ == demandimport._demandimport
 
     # Shut up warning about uninitialized logging for new keyring versions.
     # But beware 2.6…
     try:
         import logging
         logging.getLogger("keyring").addHandler(logging.NullHandler())
     except:  # pylint: disable=bare-except
         pass
 
     # Temporarily disable demandimport to make the need of extending
     # the list above less likely.
     if is_demandimport_enabled():
         demandimport.disable()
         try:
             import keyring
         finally:
             demandimport.enable()
     else:
         import keyring
     return keyring
 
 #################################################################
 # Actual implementation
 #################################################################
 
 KEYRING_SERVICE = "Mercurial"
 
 
 class PasswordStore(object):
     """
     Helper object handling keyring usage (password save&restore,
     the way passwords are keyed in the keyring).
     """
     def __init__(self):
         self.cache = dict()
 
     def get_http_password(self, url, username):
         """
         Checks whether password of username for url is available,
         returns it or None
         """
         return self._read_password_from_keyring(
             self._format_http_key(url, username))
 
     def set_http_password(self, url, username, password):
         """Saves password to keyring"""
         self._save_password_to_keyring(
             self._format_http_key(url, username),
             password)
 
     def clear_http_password(self, url, username):
         """Drops saved password"""
         self.set_http_password(url, username, "")
 
     @staticmethod
     def _format_http_key(url, username):
         """Construct actual key for password identification"""
         return "%s@@%s" % (username, url)
 
     def get_smtp_password(self, machine, port, username):
         """Checks for SMTP password in keyring, returns
         password or None"""
         return self._read_password_from_keyring(
             self._format_smtp_key(machine, port, username))
 
     def set_smtp_password(self, machine, port, username, password):
         """Saves SMTP password to keyring"""
         self._save_password_to_keyring(
             self._format_smtp_key(machine, port, username),
             password)
 
     def clear_smtp_password(self, machine, port, username):
         """Drops saved SMTP password"""
         self.set_smtp_password(machine, port, username, "")
 
     @staticmethod
     def _format_smtp_key(machine, port, username):
         """Construct key for SMTP password identification"""
         return "%s@@%s:%s" % (username, machine, str(port))
 
     @staticmethod
     def _read_password_from_keyring(pwdkey):
         """Physically read from keyring"""
         keyring = import_keyring()
         password = keyring.get_password(KEYRING_SERVICE, pwdkey)
         # Reverse recoding from next routine
         if isinstance(password, unicode):
             return encoding.tolocal(password.encode('utf-8'))
         return password
 
     @staticmethod
     def _save_password_to_keyring(pwdkey, password):
         """Physically write to keyring"""
         keyring = import_keyring()
         # keyring in general expects unicode.
         # Mercurial provides "local" encoding. See #33
         password = encoding.fromlocal(password).decode('utf-8')
         keyring.set_password(
             KEYRING_SERVICE, pwdkey, password)
 
 password_store = PasswordStore()
 
 
 ############################################################
 # Various utils
 ############################################################
 
 def _debug(ui, msg):
     """Generic debug message"""
     ui.debug("keyring: " + msg + "\n")
 
 
 class PwdCache(object):
     """Short term cache, used to preserve passwords
     if they are used twice during a command"""
     def __init__(self):
         self._cache = {}
 
     def store(self, realm, url, user, pwd):
         """Saves password"""
         cache_key = (realm, url, user)
         self._cache[cache_key] = pwd
 
     def check(self, realm, url, user):
         """Checks for cached password"""
         cache_key = (realm, url, user)
         return self._cache.get(cache_key)
 
 
 ############################################################
 # HTTP password management
 ############################################################
 
 
 class HTTPPasswordHandler(object):
     """
     Actual implementation of password handling (user prompting,
     configuration file searching, keyring save&restore).
 
     Object of this class is bound as passwordmgr attribute.
     """
     def __init__(self):
         self.pwd_cache = PwdCache()
         self.last_reply = None
 
     # Markers and also names used in debug notes. Password source
     SRC_URL = "repository URL"
     SRC_CFGAUTH = "hgrc"
     SRC_MEMCACHE = "temporary cache"
     SRC_KEYRING = "keyring"
 
     def get_credentials(self, pwmgr, realm, authuri, skip_caches=False):
         """
         Looks up for user credentials in various places, returns them
         and information about their source.
 
         Used internally inside find_auth and inside informative
         commands (thiis method doesn't cache, doesn't detect bad
         passwords etc, doesn't prompt interactively, doesn't store
         password in keyring).
 
         Returns: user, password, SRC_*, actual_url
 
         If not found, password and SRC is None, user can be given or
         not, url is always set
         """
         ui = pwmgr.ui
 
         # Strip arguments to get actual remote repository url.
         base_url = self.canonical_url(authuri)
 
         # Extract username (or password) stored directly in url
         url_user, url_pwd \
             = urllib2.HTTPPasswordMgrWithDefaultRealm.find_user_password(
                 pwmgr, realm, authuri)
         if url_user and url_pwd:
             return url_user, url_pwd, self.SRC_URL, base_url
 
         # Consult configuration to normalize url to prefix, and find username
         # (and maybe password)
         auth_user, auth_pwd, keyring_url = self.get_url_config(
             ui, base_url, url_user)
         if auth_user and url_user and (url_user != auth_user):
             raise util.Abort(_('mercurial_keyring: username for %s specified both in repository path (%s) and in .hg/hgrc/[auth] (%s). Please, leave only one of those' % (base_url, url_user, auth_user)))
         if auth_user and auth_pwd:
             return auth_user, auth_pwd, self.SRC_CFGAUTH, keyring_url
 
         if skip_caches:
             return auth_user, None, None, keyring_url
 
         # Check memory cache (reuse )
         # Checking the memory cache (there may be many http calls per command)
         cached_pwd = self.pwd_cache.check(realm, keyring_url, auth_user)
         if cached_pwd:
             return auth_user, cached_pwd, self.SRC_MEMCACHE, keyring_url
 
         # Load from keyring.
         if auth_user:
             ui.debug(_("keyring: looking for password (user %s, url %s)\n") % (auth_user, keyring_url))
             keyring_pwd = password_store.get_http_password(keyring_url, auth_user)
             if keyring_pwd:
                 return auth_user, keyring_pwd, self.SRC_KEYRING, keyring_url
 
         return auth_user, None, None, keyring_url
 
 
     @staticmethod
     def prompt_interactively(ui, user, realm, url):
         """Actual interactive prompt"""
         if not ui.interactive():
             raise util.Abort(_('mercurial_keyring: http authorization required but program used in non-interactive mode'))
 
         if not user:
             ui.status(_("keyring: username not specified in hgrc (or in url). Password will not be saved.\n"))
 
         ui.write(_("http authorization required\n"))
         ui.status(_("realm: %s\n") % realm)
         ui.status(_("url: %s\n") % url)
         if user:
             ui.write(_("user: %s (fixed in hgrc or url)\n" % user))
         else:
             user = ui.prompt(_("user:"), default=None)
         pwd = ui.getpass(_("password: "))
         return user, pwd
 
     def find_auth(self, pwmgr, realm, authuri, req):
         """
         Actual implementation of find_user_password - different
         ways of obtaining the username and password.
 
         Returns pair username, password
         """
         ui = pwmgr.ui
         after_bad_auth = self._after_bad_auth(ui, realm, authuri, req)
 
         # Look in url, cache, etc
         user, pwd, src, final_url = self.get_credentials(
             pwmgr, realm, authuri, skip_caches=after_bad_auth)
         if pwd:
             if src != self.SRC_MEMCACHE:
                 self.pwd_cache.store(realm, final_url, user, pwd)
             self._note_last_reply(realm, authuri, user, req)
             _debug(ui, _("Password found in " + src))
             return user, pwd
 
         # Last resort: interactive prompt
         user, pwd = self.prompt_interactively(ui, user, realm, final_url)
 
         if user:
             # Saving password to the keyring.
             # It is done only if username is permanently set.
             # Otherwise we won't be able to find the password so it
             # does not make much sense to preserve it
             _debug(ui, _("Saving password for %s to keyring") % user)
             password_store.set_http_password(final_url, user, pwd)
 
         # Saving password to the memory cache
         self.pwd_cache.store(realm, final_url, user, pwd)
         self._note_last_reply(realm, authuri, user, req)
         _debug(ui, _("Manually entered password"))
         return user, pwd
 
     def get_url_config(self, ui, base_url, user):
         """
         Checks configuration to decide whether/which username, prefix,
         and password are configured for given url. Consults [auth] section.
 
         Returns tuple (username, password, prefix) containing elements
         found. username and password can be None (if unset), if prefix
         is not found, url itself is returned.
         """
         from mercurial.httpconnection import readauthforuri
         _debug(ui, _("Checking for hgrc info about url %s, user %s") % (base_url, user))
         res = readauthforuri(ui, base_url, user)
         if res:
             group, auth_token = res
         else:
             auth_token = None
 
         if auth_token:
             username = auth_token.get('username')
             password = auth_token.get('password')
             prefix = auth_token.get('prefix')
         else:
             username = None
             password = None
             prefix = None
 
         password_url = self.password_url(base_url, prefix)
         return username, password, password_url
 
     def _note_last_reply(self, realm, authuri, user, req):
         """
         Internal helper. Saves info about auth-data obtained,
         preserves them in last_reply, and returns pair user, pwd
         """
         self.last_reply = dict(realm=realm, authuri=authuri,
                                user=user, req=req)
 
     def _after_bad_auth(self, ui, realm, authuri, req):
         """
         If we are called again just after identical previous
         request, then the previously returned auth must have been
         wrong. So we note this to force password prompt (and avoid
         reusing bad password indefinitely).
 
         This routine checks for this condition.
         """
         if self.last_reply:
             if (self.last_reply['realm'] == realm) \
                and (self.last_reply['authuri'] == authuri) \
                and (self.last_reply['req'] == req):
                 _debug(ui, _("Working after bad authentication, cached passwords not used %s") % str(self.last_reply))
                 return True
         return False
 
     @staticmethod
     def password_url(base_url, prefix):
         """Calculates actual url identifying the password. Takes
         configured prefix under consideration (so can be shorter
         than repo url)"""
         if not prefix or prefix == '*':
             return base_url
         scheme, hostpath = base_url.split('://', 1)
         p = prefix.split('://', 1)
         if len(p) > 1:
             prefix_host_path = p[1]
         else:
             prefix_host_path = prefix
         password_url = scheme + '://' + prefix_host_path
         return password_url
 
     @staticmethod
     def canonical_url(authuri):
         """
         Strips query params from url. Used to convert urls like
         https://repo.machine.com/repos/apps/module?pairs=0000000000000000000000000000000000000000-0000000000000000000000000000000000000000&cmd=between
         to
         https://repo.machine.com/repos/apps/module
         """
         parsed_url = urlparse(authuri)
         return "%s://%s%s" % (parsed_url.scheme, parsed_url.netloc,
                               parsed_url.path)
 
 ############################################################
 # Mercurial monkey-patching
 ############################################################
 
 
 @monkeypatch_method(passwordmgr)
 def find_user_password(self, realm, authuri):
     """
     keyring-based implementation of username/password query
     for HTTP(S) connections
 
     Passwords are saved in gnome keyring, OSX/Chain or other platform
     specific storage and keyed by the repository url
     """
     # Extend object attributes
     if not hasattr(self, '_pwd_handler'):
         self._pwd_handler = HTTPPasswordHandler()
 
     if hasattr(self, '_http_req'):
         req = self._http_req
     else:
         req = None
 
     return self._pwd_handler.find_auth(self, realm, authuri, req)
 
 
 @monkeypatch_method(urllib2.AbstractBasicAuthHandler, "http_error_auth_reqed")
 def basic_http_error_auth_reqed(self, authreq, host, req, headers):
     """Preserves current HTTP request so it can be consulted
     in find_user_password above"""
     self.passwd._http_req = req
     try:
         return basic_http_error_auth_reqed.orig(self, authreq, host, req, headers)
     finally:
         self.passwd._http_req = None
 
 
 @monkeypatch_method(urllib2.AbstractDigestAuthHandler, "http_error_auth_reqed")
 def digest_http_error_auth_reqed(self, authreq, host, req, headers):
     """Preserves current HTTP request so it can be consulted
     in find_user_password above"""
     self.passwd._http_req = req
     try:
         return digest_http_error_auth_reqed.orig(self, authreq, host, req, headers)
     finally:
         self.passwd._http_req = None
 
 ############################################################
 # SMTP support
 ############################################################
 
 
 def try_smtp_login(ui, smtp_obj, username, password):
     """
     Attempts smtp login on smtp_obj (smtplib.SMTP) using username and
     password.
 
     Returns:
     - True if login succeeded
     - False if login failed due to the wrong credentials
 
     Throws Abort exception if login failed for any other reason.
 
     Immediately returns False if password is empty
     """
     if not password:
         return False
     try:
         ui.note(_('(authenticating to mail server as %s)\n') %
                  (username))
         smtp_obj.login(username, password)
         return True
     except smtplib.SMTPException, inst:
         if inst.smtp_code == 535:
             ui.status(_("SMTP login failed: %s\n\n") % inst.smtp_error)
             return False
         else:
             raise util.Abort(inst)
 
 
 def keyring_supported_smtp(ui, username):
     """
     keyring-integrated replacement for mercurial.mail._smtp
     Used only when configuration file contains username, but
     does not contain the password.
 
     Most of the routine below is copied as-is from
     mercurial.mail._smtp. The only changed part is
     marked with # >>>>> and # <<<<< markers
     """
     local_hostname = ui.config('smtp', 'local_hostname')
     tls = ui.config('smtp', 'tls', 'none')
     # backward compatible: when tls = true, we use starttls.
     starttls = tls == 'starttls' or util.parsebool(tls)
     smtps = tls == 'smtps'
     if (starttls or smtps) and not util.safehasattr(socket, 'ssl'):
         raise util.Abort(_("can't use TLS: Python SSL support not installed"))
     mailhost = ui.config('smtp', 'host')
     if not mailhost:
         raise util.Abort(_('smtp.host not configured - cannot send mail'))
     verifycert = ui.config('smtp', 'verifycert', 'strict')
     if verifycert not in ['strict', 'loose']:
         if util.parsebool(verifycert) is not False:
             raise util.Abort(_('invalid smtp.verifycert configuration: %s')
                              % (verifycert))
         verifycert = False
     if (starttls or smtps) and verifycert:
         sslkwargs = sslutil.sslkwargs(ui, mailhost)
     else:
         sslkwargs = {}
     if smtps:
         ui.note(_('(using smtps)\n'))
         s = SMTPS(sslkwargs, local_hostname=local_hostname)
     elif starttls:
         s = STARTTLS(sslkwargs, local_hostname=local_hostname)
     else:
         s = smtplib.SMTP(local_hostname=local_hostname)
     if smtps:
         defaultport = 465
     else:
         defaultport = 25
     mailport = util.getport(ui.config('smtp', 'port', defaultport))
     ui.note(_('sending mail: smtp host %s, port %s\n') %
             (mailhost, mailport))
     s.connect(host=mailhost, port=mailport)
     if starttls:
         ui.note(_('(using starttls)\n'))
         s.ehlo()
         s.starttls()
         s.ehlo()
     if (starttls or smtps) and verifycert:
         ui.note(_('(verifying remote certificate)\n'))
         sslutil.validator(ui, mailhost)(s.sock, verifycert == 'strict')
 
     # >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
     stored = password = password_store.get_smtp_password(
         mailhost, mailport, username)
     # No need to check whether password was found as try_smtp_login
     # just returns False if it is absent.
     while not try_smtp_login(ui, s, username, password):
         password = ui.getpass(_("Password for %s on %s:%d: ") % (username, mailhost, mailport))
 
     if stored != password:
         password_store.set_smtp_password(
             mailhost, mailport, username, password)
     # <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
 
     def send(sender, recipients, msg):
         try:
             return s.sendmail(sender, recipients, msg)
         except smtplib.SMTPRecipientsRefused, inst:
             recipients = [r[1] for r in inst.recipients.values()]
             raise util.Abort('\n' + '\n'.join(recipients))
         except smtplib.SMTPException, inst:
             raise util.Abort(inst)
 
     return send
 
 ############################################################
 # SMTP monkeypatching
 ############################################################
 
 
 @monkeypatch_method(mail)
 def _smtp(ui):
     """
     build an smtp connection and return a function to send email
 
     This is the monkeypatched version of _smtp(ui) function from
     mercurial/mail.py. It calls the original unless username
     without password is given in the configuration.
     """
     username = ui.config('smtp', 'username')
     password = ui.config('smtp', 'password')
 
     if username and not password:
         return keyring_supported_smtp(ui, username)
     else:
         return _smtp.orig(ui)
 
 
 ############################################################
 # Custom commands
 ############################################################
 
-def cmd_keyring_check(ui, repo, *path_args, **opts):
+_re_http_url = re.compile(r'^https?://')
+
+def is_http_path(url):
+    return bool(_re_http_url.search(url))
+
+
+def cmd_keyring_check(ui, repo, *path_args, **opts):   # pylint: disable=unused-argument
     """
     Prints basic info (whether password is currently saved, and how is
     it identified) for given path or for all defined repo paths which are HTTP.
     """
-    import re
-
-    re_http_url = re.compile(r'^https?://')
     defined_paths = [(name, url)
                      for name, url in ui.configitems('paths')]
     if path_args:
         # Maybe parameter is an alias
         defined_paths_dic = dict(defined_paths)
         paths = [(path_arg, defined_paths_dic.get(path_arg, path_arg))
                  for path_arg in path_args]
     else:
         paths = [(name, url) for name, url in defined_paths]
 
     if not paths:
-        ui.status(_("keyring_check: no paths defined"))
+        ui.status(_("keyring_check: no paths defined\n"))
 
     handler = HTTPPasswordHandler()
 
     ui.status(_("keyring password save status:\n"))
     for name, url in paths:
-        if not re_http_url.search(url):
+        if not is_http_path(url):
             if path_args:
                 ui.status(_("    %s: non-http path (%s)\n") % (name, url))
             continue
-        user, pwd, source, final_url = handler.get_credentials(passwordmgr(ui), name, url)
+        user, pwd, source, final_url = handler.get_credentials(
+            passwordmgr(ui), name, url)
         if pwd:
             ui.status(_("    %s: password available, source: %s, bound to user %s, url %s\n") % (
                 name, source, user, final_url))
         elif user:
             ui.status(_("    %s: password not available, once entered, will be bound to user %s, url %s\n") % (
                 name, user, final_url))
         else:
             ui.status(_("    %s: password not available, user unknown, url %s\n") % (
                 name, final_url))
 
 
-def cmd_keyring_clear(ui, repo, path, **opts):
+def cmd_keyring_clear(ui, repo, path, **opts):  # pylint: disable=unused-argument
+    """
+    Drops password bound to given path (if any is saved).
     """
-    Drops password bound to given path (if any).
-    """
-    # TODO
-    ui.status(_("Not yet implemented"))
+    path_url = path
+    for name, url in ui.configitems('paths'):
+        if name == path:
+            path_url = url
+            break
+    if not is_http_path(path_url):
+        ui.warn(_("%s is not a http path (%s)") % (path, path_url))
+        return
+
+    handler = HTTPPasswordHandler()
+
+    user, pwd, source, final_url = handler.get_credentials(
+        passwordmgr(ui), path, path_url)
+    if not user:
+        ui.status(_("Username not configured for url %s\n") % final_url)
+        return
+    if not pwd:
+        ui.status(_("No password is saved for user %s, url %s\n") % (
+            user, final_url))
+        return
+
+    if source != handler.SRC_KEYRING:
+        ui.status(_("Password for user %s, url %s is saved in %s, not in keyring\n") % (
+            user, final_url, source))
+
+    password_store.clear_http_password(final_url, user)
+    ui.status(_("Password removed for user %s, url %s\n") % (
+        user, final_url))
 
 
 cmdtable = {
     "keyring_check": (
         cmd_keyring_check,
         [],
         "keyring_check [PATH]",
     ),
     "keyring_clear": (
         cmd_keyring_clear,
         [],
         "keyring_check PATH",
     ),
 }