indygreg created this revision.
Herald added a subscriber: mercurial-devel.
Herald added a reviewer: hg-reviewers.

REVISION SUMMARY
  HTTP messages communicate their media types and what media types
  they can understand via the Content-Type and Accept header,
  respectively.
  
  While I don't want the wire protocol to lean too heavily on HTTP
  because I'm aiming for the wire protocol to be as transport
  agnostic as possible, it is nice to play by the spec if possible.
  
  This commit defines our media negotiation mechanism for version
  2 of the HTTP protocol. Essentially, we mandate the use of a
  new media type and how clients and servers should react to
  various headers or lack thereof.
  
  The name of the media type is a placeholder. We purposefully don't
  yet define the format of the new media type because that's a lot
  of work.
  
  I feel pretty strongly that we should use Content-Type. I feel
  less strongly about Accept. I think it is reasonable for servers
  to return the media type that was submitted to them. So we may
  strike this header before the protocol is finished...

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D2850

AFFECTED FILES
  mercurial/help/internals/wireprotocol.txt
  mercurial/wireprotoserver.py
  tests/test-http-api-httpv2.t

CHANGE DETAILS

diff --git a/tests/test-http-api-httpv2.t b/tests/test-http-api-httpv2.t
--- a/tests/test-http-api-httpv2.t
+++ b/tests/test-http-api-httpv2.t
@@ -1,4 +1,5 @@
   $ HTTPV2=exp-http-v2-0001
+  $ MEDIATYPE=application/mercurial-tbd
 
   $ send() {
   >   hg --verbose debugwireproto --peer raw http://$LOCALIP:$HGPORT/
@@ -45,27 +46,6 @@
   $ hg -R server serve -p $HGPORT -d --pid-file hg.pid
   $ cat hg.pid > $DAEMON_PIDS
 
-Request to read-only command works out of the box
-
-  $ send << EOF
-  > httprequest POST api/$HTTPV2/ro/known
-  >     user-agent: test
-  > EOF
-  using raw connection to peer
-  s>     POST /api/exp-http-v2-0001/ro/known HTTP/1.1\r\n
-  s>     Accept-Encoding: identity\r\n
-  s>     user-agent: test\r\n
-  s>     host: $LOCALIP:$HGPORT\r\n (glob)
-  s>     \r\n
-  s> makefile('rb', None)
-  s>     HTTP/1.1 200 OK\r\n
-  s>     Server: testing stub value\r\n
-  s>     Date: $HTTP_DATE$\r\n
-  s>     Content-Type: text/plain\r\n
-  s>     Content-Length: 9\r\n
-  s>     \r\n
-  s>     ro/known\n
-
 Request to unknown command yields 404
 
   $ send << EOF
@@ -108,6 +88,100 @@
   s>     \r\n
   s>     commands require POST requests
 
+Missing Accept header results in 406
+
+  $ send << EOF
+  > httprequest POST api/$HTTPV2/ro/known
+  >     user-agent: test
+  > EOF
+  using raw connection to peer
+  s>     POST /api/exp-http-v2-0001/ro/known HTTP/1.1\r\n
+  s>     Accept-Encoding: identity\r\n
+  s>     user-agent: test\r\n
+  s>     host: $LOCALIP:$HGPORT\r\n (glob)
+  s>     \r\n
+  s> makefile('rb', None)
+  s>     HTTP/1.1 406 Not Acceptable\r\n
+  s>     Server: testing stub value\r\n
+  s>     Date: $HTTP_DATE$\r\n
+  s>     Content-Type: text/plain\r\n
+  s>     Content-Length: 72\r\n
+  s>     \r\n
+  s>     client MUST specify Accept header with value: 
application/mercurial-tbd\n
+
+Bad Accept header results in 406
+
+  $ send << EOF
+  > httprequest POST api/$HTTPV2/ro/known
+  >     accept: invalid
+  >     user-agent: test
+  > EOF
+  using raw connection to peer
+  s>     POST /api/exp-http-v2-0001/ro/known HTTP/1.1\r\n
+  s>     Accept-Encoding: identity\r\n
+  s>     accept: invalid\r\n
+  s>     user-agent: test\r\n
+  s>     host: $LOCALIP:$HGPORT\r\n (glob)
+  s>     \r\n
+  s> makefile('rb', None)
+  s>     HTTP/1.1 406 Not Acceptable\r\n
+  s>     Server: testing stub value\r\n
+  s>     Date: $HTTP_DATE$\r\n
+  s>     Content-Type: text/plain\r\n
+  s>     Content-Length: 72\r\n
+  s>     \r\n
+  s>     client MUST specify Accept header with value: 
application/mercurial-tbd\n
+
+Bad Content-Type header results in 415
+
+  $ send << EOF
+  > httprequest POST api/$HTTPV2/ro/known
+  >     accept: $MEDIATYPE
+  >     user-agent: test
+  >     content-type: badmedia
+  > EOF
+  using raw connection to peer
+  s>     POST /api/exp-http-v2-0001/ro/known HTTP/1.1\r\n
+  s>     Accept-Encoding: identity\r\n
+  s>     accept: application/mercurial-tbd\r\n
+  s>     content-type: badmedia\r\n
+  s>     user-agent: test\r\n
+  s>     host: $LOCALIP:$HGPORT\r\n (glob)
+  s>     \r\n
+  s> makefile('rb', None)
+  s>     HTTP/1.1 415 Unsupported Media Type\r\n
+  s>     Server: testing stub value\r\n
+  s>     Date: $HTTP_DATE$\r\n
+  s>     Content-Type: text/plain\r\n
+  s>     Content-Length: 75\r\n
+  s>     \r\n
+  s>     client MUST send Content-Type header with value: 
application/mercurial-tbd\n
+
+Request to read-only command works out of the box
+
+  $ send << EOF
+  > httprequest POST api/$HTTPV2/ro/known
+  >     accept: $MEDIATYPE
+  >     content-type: $MEDIATYPE
+  >     user-agent: test
+  > EOF
+  using raw connection to peer
+  s>     POST /api/exp-http-v2-0001/ro/known HTTP/1.1\r\n
+  s>     Accept-Encoding: identity\r\n
+  s>     accept: application/mercurial-tbd\r\n
+  s>     content-type: application/mercurial-tbd\r\n
+  s>     user-agent: test\r\n
+  s>     host: $LOCALIP:$HGPORT\r\n (glob)
+  s>     \r\n
+  s> makefile('rb', None)
+  s>     HTTP/1.1 200 OK\r\n
+  s>     Server: testing stub value\r\n
+  s>     Date: $HTTP_DATE$\r\n
+  s>     Content-Type: text/plain\r\n
+  s>     Content-Length: 9\r\n
+  s>     \r\n
+  s>     ro/known\n
+
 Request to read-write command fails because server is read-only by default
 
 GET to read-write request yields 405
@@ -192,10 +266,14 @@
   $ send << EOF
   > httprequest POST api/$HTTPV2/rw/known
   >     user-agent: test
+  >     accept: $MEDIATYPE
+  >     content-type: $MEDIATYPE
   > EOF
   using raw connection to peer
   s>     POST /api/exp-http-v2-0001/rw/known HTTP/1.1\r\n
   s>     Accept-Encoding: identity\r\n
+  s>     accept: application/mercurial-tbd\r\n
+  s>     content-type: application/mercurial-tbd\r\n
   s>     user-agent: test\r\n
   s>     host: $LOCALIP:$HGPORT\r\n (glob)
   s>     \r\n
@@ -213,10 +291,12 @@
   $ send << EOF
   > httprequest POST api/$HTTPV2/rw/badcommand
   >     user-agent: test
+  >     accept: $MEDIATYPE
   > EOF
   using raw connection to peer
   s>     POST /api/exp-http-v2-0001/rw/badcommand HTTP/1.1\r\n
   s>     Accept-Encoding: identity\r\n
+  s>     accept: application/mercurial-tbd\r\n
   s>     user-agent: test\r\n
   s>     host: $LOCALIP:$HGPORT\r\n (glob)
   s>     \r\n
diff --git a/mercurial/wireprotoserver.py b/mercurial/wireprotoserver.py
--- a/mercurial/wireprotoserver.py
+++ b/mercurial/wireprotoserver.py
@@ -32,6 +32,7 @@
 HGTYPE = 'application/mercurial-0.1'
 HGTYPE2 = 'application/mercurial-0.2'
 HGERRTYPE = 'application/hg-error'
+HTTPV2TYPE = 'application/mercurial-tbd'
 
 HTTPV2 = wireprototypes.HTTPV2
 SSHV1 = wireprototypes.SSHV1
@@ -335,6 +336,23 @@
         res.setbodybytes(_('invalid wire protocol command: %s') % command)
         return
 
+    if req.headers.get(b'Accept') != HTTPV2TYPE:
+        res.status = b'406 Not Acceptable'
+        res.headers[b'Content-Type'] = b'text/plain'
+        res.setbodybytes(_('client MUST specify Accept header with value: %s\n'
+                           % HTTPV2TYPE))
+        return
+
+    if (b'Content-Type' in req.headers
+        and req.headers[b'Content-Type'] != HTTPV2TYPE):
+        res.status = b'415 Unsupported Media Type'
+        # TODO we should send a response with appropriate media type,
+        # since client does Accept it.
+        res.headers[b'Content-Type'] = b'text/plain'
+        res.setbodybytes(_('client MUST send Content-Type header with '
+                           'value: %s\n') % HTTPV2TYPE)
+        return
+
     # We don't do anything meaningful yet.
     res.status = b'200 OK'
     res.headers[b'Content-Type'] = b'text/plain'
diff --git a/mercurial/help/internals/wireprotocol.txt 
b/mercurial/help/internals/wireprotocol.txt
--- a/mercurial/help/internals/wireprotocol.txt
+++ b/mercurial/help/internals/wireprotocol.txt
@@ -187,6 +187,19 @@
 Requests to unknown commands or URLS result in an HTTP 404.
 TODO formally define response type, how error is communicated, etc.
 
+HTTP request and response bodies use the *TBD Protocol* for media exchange.
+
+Clients and servers MUST advertise the ``TBD`` media type via the
+``Content-Type`` request and response headers. In addition, clients MUST
+advertise this media type value in their ``Accept`` request header in all
+requests.
+
+Servers receiving requests without an ``Accept`` header SHOULD respond with
+an HTTP 406.
+
+Servers receiving requests with an invalid ``Content-Type`` header SHOULD
+respond with an HTTP 415.
+
 SSH Protocol
 ============
 



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