wireprotoserver: move error response handling out of hgweb

The exception handler for ErrorResponse has more to do with the
wire protocol than the generic HTTP server. Move the code so it
lives alongside other wire protocol code.

Differential Revision: https://phab.mercurial-scm.org/D2021

mercurial/hgweb/hgweb_mod.py

@@ -1,494 +1,483 b''
 # hgweb/hgweb_mod.py - Web interface for a repository.
 #
 # Copyright 21 May 2005 - (c) 2005 Jake Edge <[e-mail]>
 # Copyright 2005-2007 Matt Mackall <[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 contextlib
 import os
 
 from .common import (
     ErrorResponse,
     HTTP_BAD_REQUEST,
     HTTP_NOT_FOUND,
     HTTP_NOT_MODIFIED,
     HTTP_OK,
     HTTP_SERVER_ERROR,
     caching,
     cspvalues,
     permhooks,
 )
 from .request import wsgirequest
 
 from .. import (
     encoding,
     error,
     hg,
     hook,
     profiling,
     pycompat,
     repoview,
     templatefilters,
     templater,
     ui as uimod,
     util,
     wireprotoserver,
 )
 
 from . import (
     webcommands,
     webutil,
     wsgicgi,
 )
 
 perms = {
     'changegroup': 'pull',
     'changegroupsubset': 'pull',
     'getbundle': 'pull',
     'stream_out': 'pull',
     'listkeys': 'pull',
     'unbundle': 'push',
     'pushkey': 'push',
 }
 
 archivespecs = util.sortdict((
     ('zip', ('application/zip', 'zip', '.zip', None)),
     ('gz', ('application/x-gzip', 'tgz', '.tar.gz', None)),
     ('bz2', ('application/x-bzip2', 'tbz2', '.tar.bz2', None)),
 ))
 
 def getstyle(req, configfn, templatepath):
     fromreq = req.form.get('style', [None])[0]
     if fromreq is not None:
         fromreq = pycompat.sysbytes(fromreq)
     styles = (
         fromreq,
         configfn('web', 'style'),
         'paper',
     )
     return styles, templater.stylemap(styles, templatepath)
 
 def makebreadcrumb(url, prefix=''):
     '''Return a 'URL breadcrumb' list
 
     A 'URL breadcrumb' is a list of URL-name pairs,
     corresponding to each of the path items on a URL.
     This can be used to create path navigation entries.
     '''
     if url.endswith('/'):
         url = url[:-1]
     if prefix:
         url = '/' + prefix + url
     relpath = url
     if relpath.startswith('/'):
         relpath = relpath[1:]
 
     breadcrumb = []
     urlel = url
     pathitems = [''] + relpath.split('/')
     for pathel in reversed(pathitems):
         if not pathel or not urlel:
             break
         breadcrumb.append({'url': urlel, 'name': pathel})
         urlel = os.path.dirname(urlel)
     return reversed(breadcrumb)
 
 class requestcontext(object):
     """Holds state/context for an individual request.
 
     Servers can be multi-threaded. Holding state on the WSGI application
     is prone to race conditions. Instances of this class exist to hold
     mutable and race-free state for requests.
     """
     def __init__(self, app, repo):
         self.repo = repo
         self.reponame = app.reponame
 
         self.archivespecs = archivespecs
 
         self.maxchanges = self.configint('web', 'maxchanges')
         self.stripecount = self.configint('web', 'stripes')
         self.maxshortchanges = self.configint('web', 'maxshortchanges')
         self.maxfiles = self.configint('web', 'maxfiles')
         self.allowpull = self.configbool('web', 'allow-pull')
 
         # we use untrusted=False to prevent a repo owner from using
         # web.templates in .hg/hgrc to get access to any file readable
         # by the user running the CGI script
         self.templatepath = self.config('web', 'templates', untrusted=False)
 
         # This object is more expensive to build than simple config values.
         # It is shared across requests. The app will replace the object
         # if it is updated. Since this is a reference and nothing should
         # modify the underlying object, it should be constant for the lifetime
         # of the request.
         self.websubtable = app.websubtable
 
         self.csp, self.nonce = cspvalues(self.repo.ui)
 
     # Trust the settings from the .hg/hgrc files by default.
     def config(self, section, name, default=uimod._unset, untrusted=True):
         return self.repo.ui.config(section, name, default,
                                    untrusted=untrusted)
 
     def configbool(self, section, name, default=uimod._unset, untrusted=True):
         return self.repo.ui.configbool(section, name, default,
                                        untrusted=untrusted)
 
     def configint(self, section, name, default=uimod._unset, untrusted=True):
         return self.repo.ui.configint(section, name, default,
                                       untrusted=untrusted)
 
     def configlist(self, section, name, default=uimod._unset, untrusted=True):
         return self.repo.ui.configlist(section, name, default,
                                        untrusted=untrusted)
 
     def archivelist(self, nodeid):
         allowed = self.configlist('web', 'allow_archive')
         for typ, spec in self.archivespecs.iteritems():
             if typ in allowed or self.configbool('web', 'allow%s' % typ):
                 yield {'type': typ, 'extension': spec[2], 'node': nodeid}
 
     def templater(self, req):
         # determine scheme, port and server name
         # this is needed to create absolute urls
 
         proto = req.env.get('wsgi.url_scheme')
         if proto == 'https':
             proto = 'https'
             default_port = '443'
         else:
             proto = 'http'
             default_port = '80'
 
         port = req.env[r'SERVER_PORT']
         port = port != default_port and (r':' + port) or r''
         urlbase = r'%s://%s%s' % (proto, req.env[r'SERVER_NAME'], port)
         logourl = self.config('web', 'logourl')
         logoimg = self.config('web', 'logoimg')
         staticurl = self.config('web', 'staticurl') or req.url + 'static/'
         if not staticurl.endswith('/'):
             staticurl += '/'
 
         # some functions for the templater
 
         def motd(**map):
             yield self.config('web', 'motd')
 
         # figure out which style to use
 
         vars = {}
         styles, (style, mapfile) = getstyle(req, self.config,
                                             self.templatepath)
         if style == styles[0]:
             vars['style'] = style
 
         start = '&' if req.url[-1] == r'?' else '?'
         sessionvars = webutil.sessionvars(vars, start)
 
         if not self.reponame:
             self.reponame = (self.config('web', 'name', '')
                              or req.env.get('REPO_NAME')
                              or req.url.strip('/') or self.repo.root)
 
         def websubfilter(text):
             return templatefilters.websub(text, self.websubtable)
 
         # create the templater
 
         defaults = {
             'url': req.url,
             'logourl': logourl,
             'logoimg': logoimg,
             'staticurl': staticurl,
             'urlbase': urlbase,
             'repo': self.reponame,
             'encoding': encoding.encoding,
             'motd': motd,
             'sessionvars': sessionvars,
             'pathdef': makebreadcrumb(req.url),
             'style': style,
             'nonce': self.nonce,
         }
         tmpl = templater.templater.frommapfile(mapfile,
                                                filters={'websub': websubfilter},
                                                defaults=defaults)
         return tmpl
 
 
 class hgweb(object):
     """HTTP server for individual repositories.
 
     Instances of this class serve HTTP responses for a particular
     repository.
 
     Instances are typically used as WSGI applications.
 
     Some servers are multi-threaded. On these servers, there may
     be multiple active threads inside __call__.
     """
     def __init__(self, repo, name=None, baseui=None):
         if isinstance(repo, str):
             if baseui:
                 u = baseui.copy()
             else:
                 u = uimod.ui.load()
             r = hg.repository(u, repo)
         else:
             # we trust caller to give us a private copy
             r = repo
 
         r.ui.setconfig('ui', 'report_untrusted', 'off', 'hgweb')
         r.baseui.setconfig('ui', 'report_untrusted', 'off', 'hgweb')
         r.ui.setconfig('ui', 'nontty', 'true', 'hgweb')
         r.baseui.setconfig('ui', 'nontty', 'true', 'hgweb')
         # resolve file patterns relative to repo root
         r.ui.setconfig('ui', 'forcecwd', r.root, 'hgweb')
         r.baseui.setconfig('ui', 'forcecwd', r.root, 'hgweb')
         # displaying bundling progress bar while serving feel wrong and may
         # break some wsgi implementation.
         r.ui.setconfig('progress', 'disable', 'true', 'hgweb')
         r.baseui.setconfig('progress', 'disable', 'true', 'hgweb')
         self._repos = [hg.cachedlocalrepo(self._webifyrepo(r))]
         self._lastrepo = self._repos[0]
         hook.redirect(True)
         self.reponame = name
 
     def _webifyrepo(self, repo):
         repo = getwebview(repo)
         self.websubtable = webutil.getwebsubs(repo)
         return repo
 
     @contextlib.contextmanager
     def _obtainrepo(self):
         """Obtain a repo unique to the caller.
 
         Internally we maintain a stack of cachedlocalrepo instances
         to be handed out. If one is available, we pop it and return it,
         ensuring it is up to date in the process. If one is not available,
         we clone the most recently used repo instance and return it.
 
         It is currently possible for the stack to grow without bounds
         if the server allows infinite threads. However, servers should
         have a thread limit, thus establishing our limit.
         """
         if self._repos:
             cached = self._repos.pop()
             r, created = cached.fetch()
         else:
             cached = self._lastrepo.copy()
             r, created = cached.fetch()
         if created:
             r = self._webifyrepo(r)
 
         self._lastrepo = cached
         self.mtime = cached.mtime
         try:
             yield r
         finally:
             self._repos.append(cached)
 
     def run(self):
         """Start a server from CGI environment.
 
         Modern servers should be using WSGI and should avoid this
         method, if possible.
         """
         if not encoding.environ.get('GATEWAY_INTERFACE',
                                     '').startswith("CGI/1."):
             raise RuntimeError("This function is only intended to be "
                                "called while running as a CGI script.")
         wsgicgi.launch(self)
 
     def __call__(self, env, respond):
         """Run the WSGI application.
 
         This may be called by multiple threads.
         """
         req = wsgirequest(env, respond)
         return self.run_wsgi(req)
 
     def run_wsgi(self, req):
         """Internal method to run the WSGI application.
 
         This is typically only called by Mercurial. External consumers
         should be using instances of this class as the WSGI application.
         """
         with self._obtainrepo() as repo:
             profile = repo.ui.configbool('profiling', 'enabled')
             with profiling.profile(repo.ui, enabled=profile):
                 for r in self._runwsgi(req, repo):
                     yield r
 
     def _runwsgi(self, req, repo):
         rctx = requestcontext(self, repo)
 
         # This state is global across all threads.
         encoding.encoding = rctx.config('web', 'encoding')
         rctx.repo.ui.environ = req.env
 
         if rctx.csp:
             # hgwebdir may have added CSP header. Since we generate our own,
             # replace it.
             req.headers = [h for h in req.headers
                            if h[0] != 'Content-Security-Policy']
             req.headers.append(('Content-Security-Policy', rctx.csp))
 
         # work with CGI variables to create coherent structure
         # use SCRIPT_NAME, PATH_INFO and QUERY_STRING as well as our REPO_NAME
 
         req.url = req.env[r'SCRIPT_NAME']
         if not req.url.endswith('/'):
             req.url += '/'
         if req.env.get('REPO_NAME'):
             req.url += req.env[r'REPO_NAME'] + r'/'
 
         if r'PATH_INFO' in req.env:
             parts = req.env[r'PATH_INFO'].strip('/').split('/')
             repo_parts = req.env.get(r'REPO_NAME', r'').split(r'/')
             if parts[:len(repo_parts)] == repo_parts:
                 parts = parts[len(repo_parts):]
             query = '/'.join(parts)
         else:
             query = req.env[r'QUERY_STRING'].partition(r'&')[0]
             query = query.partition(r';')[0]
 
         # Route it to a wire protocol handler if it looks like a wire protocol
         # request.
         protohandler = wireprotoserver.parsehttprequest(rctx.repo, req, query)
 
         if protohandler:
             cmd = protohandler['cmd']
             try:
                 if query:
                     raise ErrorResponse(HTTP_NOT_FOUND)
                 if cmd in perms:
                     self.check_perm(rctx, req, perms[cmd])
             except ErrorResponse as inst:
-                # A client that sends unbundle without 100-continue will
-                # break if we respond early.
-                if (cmd == 'unbundle' and
-                    (req.env.get('HTTP_EXPECT',
-                                 '').lower() != '100-continue') or
-                    req.env.get('X-HgHttp2', '')):
-                    req.drain()
-                else:
-                    req.headers.append((r'Connection', r'Close'))
-                req.respond(inst, wireprotoserver.HGTYPE,
-                            body='0\n%s\n' % inst)
-                return ''
+                return protohandler['handleerror'](inst)
 
             return protohandler['dispatch']()
 
         # translate user-visible url structure to internal structure
 
         args = query.split('/', 2)
         if r'cmd' not in req.form and args and args[0]:
             cmd = args.pop(0)
             style = cmd.rfind('-')
             if style != -1:
                 req.form['style'] = [cmd[:style]]
                 cmd = cmd[style + 1:]
 
             # avoid accepting e.g. style parameter as command
             if util.safehasattr(webcommands, cmd):
                 req.form[r'cmd'] = [cmd]
 
             if cmd == 'static':
                 req.form['file'] = ['/'.join(args)]
             else:
                 if args and args[0]:
                     node = args.pop(0).replace('%2F', '/')
                     req.form['node'] = [node]
                 if args:
                     req.form['file'] = args
 
             ua = req.env.get('HTTP_USER_AGENT', '')
             if cmd == 'rev' and 'mercurial' in ua:
                 req.form['style'] = ['raw']
 
             if cmd == 'archive':
                 fn = req.form['node'][0]
                 for type_, spec in rctx.archivespecs.iteritems():
                     ext = spec[2]
                     if fn.endswith(ext):
                         req.form['node'] = [fn[:-len(ext)]]
                         req.form['type'] = [type_]
         else:
             cmd = pycompat.sysbytes(req.form.get(r'cmd', [r''])[0])
 
         # process the web interface request
 
         try:
             tmpl = rctx.templater(req)
             ctype = tmpl('mimetype', encoding=encoding.encoding)
             ctype = templater.stringify(ctype)
 
             # check read permissions non-static content
             if cmd != 'static':
                 self.check_perm(rctx, req, None)
 
             if cmd == '':
                 req.form[r'cmd'] = [tmpl.cache['default']]
                 cmd = req.form[r'cmd'][0]
 
             # Don't enable caching if using a CSP nonce because then it wouldn't
             # be a nonce.
             if rctx.configbool('web', 'cache') and not rctx.nonce:
                 caching(self, req) # sets ETag header or raises NOT_MODIFIED
             if cmd not in webcommands.__all__:
                 msg = 'no such method: %s' % cmd
                 raise ErrorResponse(HTTP_BAD_REQUEST, msg)
             elif cmd == 'file' and r'raw' in req.form.get(r'style', []):
                 rctx.ctype = ctype
                 content = webcommands.rawfile(rctx, req, tmpl)
             else:
                 content = getattr(webcommands, cmd)(rctx, req, tmpl)
                 req.respond(HTTP_OK, ctype)
 
             return content
 
         except (error.LookupError, error.RepoLookupError) as err:
             req.respond(HTTP_NOT_FOUND, ctype)
             msg = str(err)
             if (util.safehasattr(err, 'name') and
                 not isinstance(err,  error.ManifestLookupError)):
                 msg = 'revision not found: %s' % err.name
             return tmpl('error', error=msg)
         except (error.RepoError, error.RevlogError) as inst:
             req.respond(HTTP_SERVER_ERROR, ctype)
             return tmpl('error', error=str(inst))
         except ErrorResponse as inst:
             req.respond(inst, ctype)
             if inst.code == HTTP_NOT_MODIFIED:
                 # Not allowed to return a body on a 304
                 return ['']
             return tmpl('error', error=str(inst))
 
     def check_perm(self, rctx, req, op):
         for permhook in permhooks:
             permhook(rctx, req, op)
 
 def getwebview(repo):
     """The 'web.view' config controls changeset filter to hgweb. Possible
     values are ``served``, ``visible`` and ``all``. Default is ``served``.
     The ``served`` filter only shows changesets that can be pulled from the
     hgweb instance.  The``visible`` filter includes secret changesets but
     still excludes "hidden" one.
 
     See the repoview module for details.
 
     The option has been around undocumented since Mercurial 2.5, but no
     user ever asked about it. So we better keep it undocumented for now."""
     # experimental config: web.view
     viewconfig = repo.ui.config('web', 'view', untrusted=True)
     if viewconfig == 'all':
         return repo.unfiltered()
     elif viewconfig in repoview.filtertable:
         return repo.filtered(viewconfig)
     else:
         return repo.filtered('served')

mercurial/wireprotoserver.py

@@ -1,404 +1,421 b''
 # Copyright 21 May 2005 - (c) 2005 Jake Edge <[e-mail]>
 # Copyright 2005-2007 Matt Mackall <[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 abc
 import cgi
 import struct
 import sys
 
 from .i18n import _
 from . import (
     encoding,
     error,
     hook,
     pycompat,
     util,
     wireproto,
 )
 
 stringio = util.stringio
 
 urlerr = util.urlerr
 urlreq = util.urlreq
 
 HTTP_OK = 200
 
 HGTYPE = 'application/mercurial-0.1'
 HGTYPE2 = 'application/mercurial-0.2'
 HGERRTYPE = 'application/hg-error'
 
 # Names of the SSH protocol implementations.
 SSHV1 = 'ssh-v1'
 # This is advertised over the wire. Incremental the counter at the end
 # to reflect BC breakages.
 SSHV2 = 'exp-ssh-v2-0001'
 
 class abstractserverproto(object):
     """abstract class that summarizes the protocol API
 
     Used as reference and documentation.
     """
 
     __metaclass__ = abc.ABCMeta
 
     @abc.abstractproperty
     def name(self):
         """The name of the protocol implementation.
 
         Used for uniquely identifying the transport type.
         """
 
     @abc.abstractmethod
     def getargs(self, args):
         """return the value for arguments in <args>
 
         returns a list of values (same order as <args>)"""
 
     @abc.abstractmethod
     def getfile(self, fp):
         """write the whole content of a file into a file like object
 
         The file is in the form::
 
             (<chunk-size>\n<chunk>)+0\n
 
         chunk size is the ascii version of the int.
         """
 
     @abc.abstractmethod
     def redirect(self):
         """may setup interception for stdout and stderr
 
         See also the `restore` method."""
 
     # If the `redirect` function does install interception, the `restore`
     # function MUST be defined. If interception is not used, this function
     # MUST NOT be defined.
     #
     # left commented here on purpose
     #
     #def restore(self):
     #    """reinstall previous stdout and stderr and return intercepted stdout
     #    """
     #    raise NotImplementedError()
 
 def decodevaluefromheaders(req, headerprefix):
     """Decode a long value from multiple HTTP request headers.
 
     Returns the value as a bytes, not a str.
     """
     chunks = []
     i = 1
     prefix = headerprefix.upper().replace(r'-', r'_')
     while True:
         v = req.env.get(r'HTTP_%s_%d' % (prefix, i))
         if v is None:
             break
         chunks.append(pycompat.bytesurl(v))
         i += 1
 
     return ''.join(chunks)
 
 class webproto(abstractserverproto):
     def __init__(self, req, ui):
         self._req = req
         self._ui = ui
 
     @property
     def name(self):
         return 'http'
 
     def getargs(self, args):
         knownargs = self._args()
         data = {}
         keys = args.split()
         for k in keys:
             if k == '*':
                 star = {}
                 for key in knownargs.keys():
                     if key != 'cmd' and key not in keys:
                         star[key] = knownargs[key][0]
                 data['*'] = star
             else:
                 data[k] = knownargs[k][0]
         return [data[k] for k in keys]
 
     def _args(self):
         args = util.rapply(pycompat.bytesurl, self._req.form.copy())
         postlen = int(self._req.env.get(r'HTTP_X_HGARGS_POST', 0))
         if postlen:
             args.update(cgi.parse_qs(
                 self._req.read(postlen), keep_blank_values=True))
             return args
 
         argvalue = decodevaluefromheaders(self._req, r'X-HgArg')
         args.update(cgi.parse_qs(argvalue, keep_blank_values=True))
         return args
 
     def getfile(self, fp):
         length = int(self._req.env[r'CONTENT_LENGTH'])
         # If httppostargs is used, we need to read Content-Length
         # minus the amount that was consumed by args.
         length -= int(self._req.env.get(r'HTTP_X_HGARGS_POST', 0))
         for s in util.filechunkiter(self._req, limit=length):
             fp.write(s)
 
     def redirect(self):
         self._oldio = self._ui.fout, self._ui.ferr
         self._ui.ferr = self._ui.fout = stringio()
 
     def restore(self):
         val = self._ui.fout.getvalue()
         self._ui.ferr, self._ui.fout = self._oldio
         return val
 
     def _client(self):
         return 'remote:%s:%s:%s' % (
             self._req.env.get('wsgi.url_scheme') or 'http',
             urlreq.quote(self._req.env.get('REMOTE_HOST', '')),
             urlreq.quote(self._req.env.get('REMOTE_USER', '')))
 
     def responsetype(self, prefer_uncompressed):
         """Determine the appropriate response type and compression settings.
 
         Returns a tuple of (mediatype, compengine, engineopts).
         """
         # Determine the response media type and compression engine based
         # on the request parameters.
         protocaps = decodevaluefromheaders(self._req, r'X-HgProto').split(' ')
 
         if '0.2' in protocaps:
             # All clients are expected to support uncompressed data.
             if prefer_uncompressed:
                 return HGTYPE2, util._noopengine(), {}
 
             # Default as defined by wire protocol spec.
             compformats = ['zlib', 'none']
             for cap in protocaps:
                 if cap.startswith('comp='):
                     compformats = cap[5:].split(',')
                     break
 
             # Now find an agreed upon compression format.
             for engine in wireproto.supportedcompengines(self._ui, self,
                                                          util.SERVERROLE):
                 if engine.wireprotosupport().name in compformats:
                     opts = {}
                     level = self._ui.configint('server',
                                               '%slevel' % engine.name())
                     if level is not None:
                         opts['level'] = level
 
                     return HGTYPE2, engine, opts
 
             # No mutually supported compression format. Fall back to the
             # legacy protocol.
 
         # Don't allow untrusted settings because disabling compression or
         # setting a very high compression level could lead to flooding
         # the server's network or CPU.
         opts = {'level': self._ui.configint('server', 'zliblevel')}
         return HGTYPE, util.compengines['zlib'], opts
 
 def iscmd(cmd):
     return cmd in wireproto.commands
 
 def parsehttprequest(repo, req, query):
     """Parse the HTTP request for a wire protocol request.
 
     If the current request appears to be a wire protocol request, this
     function returns a dict with details about that request, including
     an ``abstractprotocolserver`` instance suitable for handling the
     request. Otherwise, ``None`` is returned.
 
     ``req`` is a ``wsgirequest`` instance.
     """
     # HTTP version 1 wire protocol requests are denoted by a "cmd" query
     # string parameter. If it isn't present, this isn't a wire protocol
     # request.
     if r'cmd' not in req.form:
         return None
 
     cmd = pycompat.sysbytes(req.form[r'cmd'][0])
 
     # The "cmd" request parameter is used by both the wire protocol and hgweb.
     # While not all wire protocol commands are available for all transports,
     # if we see a "cmd" value that resembles a known wire protocol command, we
     # route it to a protocol handler. This is better than routing possible
     # wire protocol requests to hgweb because it prevents hgweb from using
     # known wire protocol commands and it is less confusing for machine
     # clients.
     if cmd not in wireproto.commands:
         return None
 
     proto = webproto(req, repo.ui)
 
     return {
         'cmd': cmd,
         'proto': proto,
         'dispatch': lambda: _callhttp(repo, req, proto, cmd),
+        'handleerror': lambda ex: _handlehttperror(ex, req, cmd),
     }
 
 def _callhttp(repo, req, proto, cmd):
     def genversion2(gen, engine, engineopts):
         # application/mercurial-0.2 always sends a payload header
         # identifying the compression engine.
         name = engine.wireprotosupport().name
         assert 0 < len(name) < 256
         yield struct.pack('B', len(name))
         yield name
 
         for chunk in gen:
             yield chunk
 
     rsp = wireproto.dispatch(repo, proto, cmd)
 
     if not wireproto.commands.commandavailable(cmd, proto):
         req.respond(HTTP_OK, HGERRTYPE,
                     body=_('requested wire protocol command is not available '
                            'over HTTP'))
         return []
 
     if isinstance(rsp, bytes):
         req.respond(HTTP_OK, HGTYPE, body=rsp)
         return []
     elif isinstance(rsp, wireproto.streamres_legacy):
         gen = rsp.gen
         req.respond(HTTP_OK, HGTYPE)
         return gen
     elif isinstance(rsp, wireproto.streamres):
         gen = rsp.gen
 
         # This code for compression should not be streamres specific. It
         # is here because we only compress streamres at the moment.
         mediatype, engine, engineopts = proto.responsetype(
             rsp.prefer_uncompressed)
         gen = engine.compressstream(gen, engineopts)
 
         if mediatype == HGTYPE2:
             gen = genversion2(gen, engine, engineopts)
 
         req.respond(HTTP_OK, mediatype)
         return gen
     elif isinstance(rsp, wireproto.pushres):
         val = proto.restore()
         rsp = '%d\n%s' % (rsp.res, val)
         req.respond(HTTP_OK, HGTYPE, body=rsp)
         return []
     elif isinstance(rsp, wireproto.pusherr):
         # drain the incoming bundle
         req.drain()
         proto.restore()
         rsp = '0\n%s\n' % rsp.res
         req.respond(HTTP_OK, HGTYPE, body=rsp)
         return []
     elif isinstance(rsp, wireproto.ooberror):
         rsp = rsp.message
         req.respond(HTTP_OK, HGERRTYPE, body=rsp)
         return []
     raise error.ProgrammingError('hgweb.protocol internal failure', rsp)
 
+def _handlehttperror(e, req, cmd):
+    """Called when an ErrorResponse is raised during HTTP request processing."""
+    # A client that sends unbundle without 100-continue will
+    # break if we respond early.
+    if (cmd == 'unbundle' and
+        (req.env.get('HTTP_EXPECT',
+                     '').lower() != '100-continue') or
+        req.env.get('X-HgHttp2', '')):
+        req.drain()
+    else:
+        req.headers.append((r'Connection', r'Close'))
+
+    req.respond(e, HGTYPE, body='0\n%s\n' % e)
+
+    return ''
+
 class sshserver(abstractserverproto):
     def __init__(self, ui, repo):
         self._ui = ui
         self._repo = repo
         self._fin = ui.fin
         self._fout = ui.fout
 
         hook.redirect(True)
         ui.fout = repo.ui.fout = ui.ferr
 
         # Prevent insertion/deletion of CRs
         util.setbinary(self._fin)
         util.setbinary(self._fout)
 
     @property
     def name(self):
         return 'ssh'
 
     def getargs(self, args):
         data = {}
         keys = args.split()
         for n in xrange(len(keys)):
             argline = self._fin.readline()[:-1]
             arg, l = argline.split()
             if arg not in keys:
                 raise error.Abort(_("unexpected parameter %r") % arg)
             if arg == '*':
                 star = {}
                 for k in xrange(int(l)):
                     argline = self._fin.readline()[:-1]
                     arg, l = argline.split()
                     val = self._fin.read(int(l))
                     star[arg] = val
                 data['*'] = star
             else:
                 val = self._fin.read(int(l))
                 data[arg] = val
         return [data[k] for k in keys]
 
     def getfile(self, fpout):
         self._sendresponse('')
         count = int(self._fin.readline())
         while count:
             fpout.write(self._fin.read(count))
             count = int(self._fin.readline())
 
     def redirect(self):
         pass
 
     def _sendresponse(self, v):
         self._fout.write("%d\n" % len(v))
         self._fout.write(v)
         self._fout.flush()
 
     def _sendstream(self, source):
         write = self._fout.write
         for chunk in source.gen:
             write(chunk)
         self._fout.flush()
 
     def _sendpushresponse(self, rsp):
         self._sendresponse('')
         self._sendresponse(str(rsp.res))
 
     def _sendpusherror(self, rsp):
         self._sendresponse(rsp.res)
 
     def _sendooberror(self, rsp):
         self._ui.ferr.write('%s\n-\n' % rsp.message)
         self._ui.ferr.flush()
         self._fout.write('\n')
         self._fout.flush()
 
     def serve_forever(self):
         while self.serve_one():
             pass
         sys.exit(0)
 
     _handlers = {
         str: _sendresponse,
         wireproto.streamres: _sendstream,
         wireproto.streamres_legacy: _sendstream,
         wireproto.pushres: _sendpushresponse,
         wireproto.pusherr: _sendpusherror,
         wireproto.ooberror: _sendooberror,
     }
 
     def serve_one(self):
         cmd = self._fin.readline()[:-1]
         if cmd and wireproto.commands.commandavailable(cmd, self):
             rsp = wireproto.dispatch(self._repo, self, cmd)
             self._handlers[rsp.__class__](self, rsp)
         elif cmd:
             self._sendresponse("")
         return cmd != ''
 
     def _client(self):
         client = encoding.environ.get('SSH_CLIENT', '').split(' ', 1)[0]
         return 'remote:ssh:' + client