indygreg updated this revision to Diff 6837.
indygreg edited the summary of this revision.

REPOSITORY
  rHG Mercurial

CHANGES SINCE LAST UPDATE
  https://phab.mercurial-scm.org/D2775?vs=6821&id=6837

REVISION DETAIL
  https://phab.mercurial-scm.org/D2775

AFFECTED FILES
  mercurial/hgweb/hgweb_mod.py
  mercurial/hgweb/request.py
  mercurial/wireprotoserver.py

CHANGE DETAILS

diff --git a/mercurial/wireprotoserver.py b/mercurial/wireprotoserver.py
--- a/mercurial/wireprotoserver.py
+++ b/mercurial/wireprotoserver.py
@@ -149,18 +149,18 @@
 def iscmd(cmd):
     return cmd in wireproto.commands
 
-def handlewsgirequest(rctx, wsgireq, req, checkperm):
+def handlewsgirequest(rctx, wsgireq, req, res, checkperm):
     """Possibly process a wire protocol request.
 
     If the current request is a wire protocol request, the request is
     processed by this function.
 
     ``wsgireq`` is a ``wsgirequest`` instance.
     ``req`` is a ``parsedrequest`` instance.
+    ``res`` is a ``wsgiresponse`` instance.
 
-    Returns a 2-tuple of (bool, response) where the 1st element indicates
-    whether the request was handled and the 2nd element is a return
-    value for a WSGI application (often a generator of bytes).
+    Returns a bool indicating if the request was serviced. If set, the caller
+    should stop processing the request, as a response has already been issued.
     """
     # Avoid cycle involving hg module.
     from .hgweb import common as hgwebcommon
@@ -171,7 +171,7 @@
     # string parameter. If it isn't present, this isn't a wire protocol
     # request.
     if 'cmd' not in req.querystringdict:
-        return False, None
+        return False
 
     cmd = req.querystringdict['cmd'][0]
 
@@ -183,18 +183,19 @@
     # known wire protocol commands and it is less confusing for machine
     # clients.
     if not iscmd(cmd):
-        return False, None
+        return False
 
     # The "cmd" query string argument is only valid on the root path of the
     # repo. e.g. ``/?cmd=foo``, ``/repo?cmd=foo``. URL paths within the repo
     # like ``/blah?cmd=foo`` are not allowed. So don't recognize the request
     # in this case. We send an HTTP 404 for backwards compatibility reasons.
     if req.dispatchpath:
-        res = _handlehttperror(
-            hgwebcommon.ErrorResponse(hgwebcommon.HTTP_NOT_FOUND), wsgireq,
-            req)
-
-        return True, res
+        res.status = hgwebcommon.statusmessage(404)
+        res.headers['Content-Type'] = HGTYPE
+        # TODO This is not a good response to issue for this request. This
+        # is mostly for BC for now.
+        res.setbodybytes('0\n%s\n' % b'Not Found')
+        return True
 
     proto = httpv1protocolhandler(wsgireq, req, repo.ui,
                                   lambda perm: checkperm(rctx, wsgireq, perm))
@@ -204,11 +205,16 @@
     # exception here. So consider refactoring into a exception type that
     # is associated with the wire protocol.
     try:
-        res = _callhttp(repo, wsgireq, req, proto, cmd)
+        _callhttp(repo, wsgireq, req, res, proto, cmd)
     except hgwebcommon.ErrorResponse as e:
-        res = _handlehttperror(e, wsgireq, req)
+        for k, v in e.headers:
+            res.headers[k] = v
+        res.status = hgwebcommon.statusmessage(e.code, pycompat.bytestr(e))
+        # TODO This response body assumes the failed command was
+        # "unbundle." That assumption is not always valid.
+        res.setbodybytes('0\n%s\n' % pycompat.bytestr(e))
 
-    return True, res
+    return True
 
 def _httpresponsetype(ui, req, prefer_uncompressed):
     """Determine the appropriate response type and compression settings.
@@ -250,7 +256,10 @@
     opts = {'level': ui.configint('server', 'zliblevel')}
     return HGTYPE, util.compengines['zlib'], opts
 
-def _callhttp(repo, wsgireq, req, proto, cmd):
+def _callhttp(repo, wsgireq, req, res, proto, cmd):
+    # Avoid cycle involving hg module.
+    from .hgweb import common as hgwebcommon
+
     def genversion2(gen, engine, engineopts):
         # application/mercurial-0.2 always sends a payload header
         # identifying the compression engine.
@@ -262,26 +271,35 @@
         for chunk in gen:
             yield chunk
 
+    def setresponse(code, contenttype, bodybytes=None, bodygen=None):
+        if code == HTTP_OK:
+            res.status = '200 Script output follows'
+        else:
+            res.status = hgwebcommon.statusmessage(code)
+
+        res.headers['Content-Type'] = contenttype
+
+        if bodybytes is not None:
+            res.setbodybytes(bodybytes)
+        if bodygen is not None:
+            res.setbodygen(bodygen)
+
     if not wireproto.commands.commandavailable(cmd, proto):
-        wsgireq.respond(HTTP_OK, HGERRTYPE,
-                        body=_('requested wire protocol command is not '
-                               'available over HTTP'))
-        return []
+        setresponse(HTTP_OK, HGERRTYPE,
+                    _('requested wire protocol command is not available over '
+                      'HTTP'))
+        return
 
     proto.checkperm(wireproto.commands[cmd].permission)
 
     rsp = wireproto.dispatch(repo, proto, cmd)
 
     if isinstance(rsp, bytes):
-        wsgireq.respond(HTTP_OK, HGTYPE, body=rsp)
-        return []
+        setresponse(HTTP_OK, HGTYPE, bodybytes=rsp)
     elif isinstance(rsp, wireprototypes.bytesresponse):
-        wsgireq.respond(HTTP_OK, HGTYPE, body=rsp.data)
-        return []
+        setresponse(HTTP_OK, HGTYPE, bodybytes=rsp.data)
     elif isinstance(rsp, wireprototypes.streamreslegacy):
-        gen = rsp.gen
-        wsgireq.respond(HTTP_OK, HGTYPE)
-        return gen
+        setresponse(HTTP_OK, HGTYPE, bodygen=rsp.gen)
     elif isinstance(rsp, wireprototypes.streamres):
         gen = rsp.gen
 
@@ -294,30 +312,18 @@
         if mediatype == HGTYPE2:
             gen = genversion2(gen, engine, engineopts)
 
-        wsgireq.respond(HTTP_OK, mediatype)
-        return gen
+        setresponse(HTTP_OK, mediatype, bodygen=gen)
     elif isinstance(rsp, wireprototypes.pushres):
         rsp = '%d\n%s' % (rsp.res, rsp.output)
-        wsgireq.respond(HTTP_OK, HGTYPE, body=rsp)
-        return []
+        setresponse(HTTP_OK, HGTYPE, bodybytes=rsp)
     elif isinstance(rsp, wireprototypes.pusherr):
         rsp = '0\n%s\n' % rsp.res
-        wsgireq.respond(HTTP_OK, HGTYPE, body=rsp)
-        return []
+        res.drain = True
+        setresponse(HTTP_OK, HGTYPE, bodybytes=rsp)
     elif isinstance(rsp, wireprototypes.ooberror):
-        rsp = rsp.message
-        wsgireq.respond(HTTP_OK, HGERRTYPE, body=rsp)
-        return []
-    raise error.ProgrammingError('hgweb.protocol internal failure', rsp)
-
-def _handlehttperror(e, wsgireq, req):
-    """Called when an ErrorResponse is raised during HTTP request 
processing."""
-
-    # TODO This response body assumes the failed command was
-    # "unbundle." That assumption is not always valid.
-    wsgireq.respond(e, HGTYPE, body='0\n%s\n' % pycompat.bytestr(e))
-
-    return ''
+        setresponse(HTTP_OK, HGERRTYPE, bodybytes=rsp.message)
+    else:
+        raise error.ProgrammingError('hgweb.protocol internal failure', rsp)
 
 def _sshv1respondbytes(fout, value):
     """Send a bytes response for protocol version 1."""
diff --git a/mercurial/hgweb/request.py b/mercurial/hgweb/request.py
--- a/mercurial/hgweb/request.py
+++ b/mercurial/hgweb/request.py
@@ -23,6 +23,7 @@
     attr,
 )
 from .. import (
+    error,
     pycompat,
     util,
 )
@@ -201,6 +202,128 @@
                          headers=headers,
                          bodyfh=bodyfh)
 
+class wsgiresponse(object):
+    """Represents a response to a WSGI request.
+
+    A response consists of a status line, headers, and a body.
+
+    Consumers must populate the ``status`` and ``headers`` fields and
+    make a call to a ``setbody*()`` method before the response can be
+    issued.
+
+    When it is time to start sending the response over the wire,
+    ``sendresponse()`` is called. It handles emitting the header portion
+    of the response message. It then yields chunks of body data to be
+    written to the peer. Typically, the WSGI application itself calls
+    and returns the value from ``sendresponse()``.
+    """
+
+    def __init__(self, req, startresponse):
+        """Create an empty response tied to a specific request.
+
+        ``req`` is a ``parsedrequest``. ``startresponse`` is the
+        ``start_response`` function passed to the WSGI application.
+        """
+        self._req = req
+        self._startresponse = startresponse
+
+        self.status = None
+        self.headers = wsgiheaders.Headers([])
+
+        self._bodybytes = None
+        self._bodygen = None
+        self._started = False
+
+    def setbodybytes(self, b):
+        """Define the response body as static bytes."""
+        if self._bodybytes is not None or self._bodygen is not None:
+            raise error.ProgrammingError('cannot define body multiple times')
+
+        self._bodybytes = b
+        self.headers['Content-Length'] = '%d' % len(b)
+
+    def setbodygen(self, gen):
+        """Define the response body as a generator of bytes."""
+        if self._bodybytes is not None or self._bodygen is not None:
+            raise error.ProgrammingError('cannot define body multiple times')
+
+        self._bodygen = gen
+
+    def sendresponse(self):
+        """Send the generated response to the client.
+
+        Before this is called, ``status`` must be set and one of
+        ``setbodybytes()`` or ``setbodygen()`` must be called.
+
+        Calling this method multiple times is not allowed.
+        """
+        if self._started:
+            raise error.ProgrammingError('sendresponse() called multiple 
times')
+
+        self._started = True
+
+        if not self.status:
+            raise error.ProgrammingError('status line not defined')
+
+        if self._bodybytes is None and self._bodygen is None:
+            raise error.ProgrammingError('response body not defined')
+
+        # Various HTTP clients (notably httplib) won't read the HTTP response
+        # until the HTTP request has been sent in full. If servers (us) send a
+        # response before the HTTP request has been fully sent, the connection
+        # may deadlock because neither end is reading.
+        #
+        # We work around this by "draining" the request data before
+        # sending any response in some conditions.
+        drain = False
+        close = False
+
+        # If the client sent Expect: 100-continue, we assume it is smart enough
+        # to deal with the server sending a response before reading the 
request.
+        # (httplib doesn't do this.)
+        if self._req.headers.get('Expect', '').lower() == '100-continue':
+            pass
+        # Only tend to request methods that have bodies. Strictly speaking,
+        # we should sniff for a body. But this is fine for our existing
+        # WSGI applications.
+        elif self._req.method not in ('POST', 'PUT'):
+            pass
+        else:
+            # If we don't know how much data to read, there's no guarantee
+            # that we can drain the request responsibly. The WSGI
+            # specification only says that servers *should* ensure the
+            # input stream doesn't overrun the actual request. So there's
+            # no guarantee that reading until EOF won't corrupt the stream
+            # state.
+            if not isinstance(self._req.bodyfh, util.cappedreader):
+                close = True
+            else:
+                # We /could/ only drain certain HTTP response codes. But 200 
and
+                # non-200 wire protocol responses both require draining. Since
+                # we have a capped reader in place for all situations where we
+                # drain, it is safe to read from that stream. We'll either do
+                # a drain or no-op if we're already at EOF.
+                drain = True
+
+        if close:
+            self.headers['Connection'] = 'Close'
+
+        if drain:
+            assert isinstance(self._req.bodyfh, util.cappedreader)
+            while True:
+                chunk = self._req.bodyfh.read(32768)
+                if not chunk:
+                    break
+
+        self._startresponse(pycompat.sysstr(self.status), self.headers.items())
+        if self._bodybytes:
+            yield self._bodybytes
+        elif self._bodygen:
+            for chunk in self._bodygen:
+                yield chunk
+        else:
+            error.ProgrammingError('do not know how to send body')
+
 class wsgirequest(object):
     """Higher-level API for a WSGI request.
 
@@ -228,6 +351,7 @@
         self.env = wsgienv
         self.req = parserequestfromenv(wsgienv, inp)
         self.form = self.req.querystringdict
+        self.res = wsgiresponse(self.req, start_response)
         self._start_response = start_response
         self.server_write = None
         self.headers = []
diff --git a/mercurial/hgweb/hgweb_mod.py b/mercurial/hgweb/hgweb_mod.py
--- a/mercurial/hgweb/hgweb_mod.py
+++ b/mercurial/hgweb/hgweb_mod.py
@@ -305,6 +305,7 @@
 
     def _runwsgi(self, wsgireq, repo):
         req = wsgireq.req
+        res = wsgireq.res
         rctx = requestcontext(self, repo)
 
         # This state is global across all threads.
@@ -317,11 +318,12 @@
             wsgireq.headers = [h for h in wsgireq.headers
                                if h[0] != 'Content-Security-Policy']
             wsgireq.headers.append(('Content-Security-Policy', rctx.csp))
+            res.headers['Content-Security-Policy'] = rctx.csp
 
-        handled, res = wireprotoserver.handlewsgirequest(
-            rctx, wsgireq, req, self.check_perm)
+        handled = wireprotoserver.handlewsgirequest(
+            rctx, wsgireq, req, res, self.check_perm)
         if handled:
-            return res
+            return res.sendresponse()
 
         if req.havepathinfo:
             query = req.dispatchpath



To: indygreg, #hg-reviewers
Cc: mercurial-devel
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