D2850: wireproto: define content negotiation for HTTPv2
indygreg (Gregory Szorc)
phabricator at mercurial-scm.org
Wed Mar 14 01:16:49 UTC 2018
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
============
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