diff mercurial/wireprotoserver.py @ 36023:cdc93fe1da77

wireprotoserver: move protocol parsing and dispatch out of hgweb

Previously, hgweb_mod had code for detecting if the request
was for the wire protocol. It would then (eventually) call
wireprotoserver.callhttp() to dispatch the request handling.

Detection of wire protocol requests is not trivial. There's
currently a big gotcha in the handling of the "cmd" request
parameter, for example.

Furthermore, in the near future we will have a second HTTP
protocol handler. Its mechanism for calling commands will be
a bit different. And we don't want the low-level logic for
detecting protocol commands to live in hgweb.

We establish a new function in wireprotoserver for detecting
an HTTP protocol request and for giving the caller an easy-to-use
mechanism for dispatching requests to it.

Some wire protocol specific functionality still lives in hgweb.
This will be addressed in subsequent commits.

Differential Revision: https://phab.mercurial-scm.org/D2019

--- a/mercurial/wireprotoserver.py	Thu Feb 01 18:48:52 2018 -0800
+++ b/mercurial/wireprotoserver.py	Wed Jan 31 16:21:43 2018 -0800
@@ -208,9 +208,43 @@
 def iscmd(cmd):
     return cmd in wireproto.commands
 
-def callhttp(repo, req, cmd):
+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),
+    }
+
+def _callhttp(repo, req, proto, cmd):
     def genversion2(gen, engine, engineopts):
         # application/mercurial-0.2 always sends a payload header
         # identifying the compression engine.