httppeer: always add x-hg* headers to Vary header

Before, we manually updated the Vary header value for each
header contributing to it.

All X-Hg* headers are reserved for the Mercurial protocol and
could have caching implications. So it makes sense to always add
these headers to Vary.

A test revealed that X-HgArgs-Post wasn't being added to Vary.
This is only sent on POST requests. POST requests generally
aren't cacheable. However, it is possible if the server sends
the appropriate headers. Mercurial shouldn't be sending those
headers. But let's not take any chances.

Differential Revision: https://phab.mercurial-scm.org/D3240

mercurial/httppeer.py

@@ -158,7 +158,6 b' def makev1commandrequest(ui, requestbuil'
     ui.debug("sending %s command\n" % cmd)
     q = [('cmd', cmd)]
     headersize = 0
-    varyheaders = []
     # Important: don't use self.capable() here or else you end up
     # with infinite recursion when trying to look up capabilities
     # for the first time.
@@ -194,7 +193,6 b' def makev1commandrequest(ui, requestbuil'
             for header, value in encodevalueinheaders(encargs, 'X-HgArg',
                                                       headersize):
                 headers[header] = value
-                varyheaders.append(header)
         # Send arguments via query string (Mercurial <1.9).
         else:
             q += sorted(args.items())
@@ -238,10 +236,14 b' def makev1commandrequest(ui, requestbuil'
                                             headersize or 1024)
         for header, value in protoheaders:
             headers[header] = value
+
+    varyheaders = []
+    for header in headers:
+        if header.lower().startswith(r'x-hg'):
             varyheaders.append(header)
 
     if varyheaders:
-        headers[r'Vary'] = r','.join(varyheaders)
+        headers[r'Vary'] = r','.join(sorted(varyheaders))
 
     req = requestbuilder(pycompat.strurl(cu), data, headers)
 

tests/test-http-bad-server.t

@@ -200,7 +200,7 b' Failure to read getbundle HTTP request'
 
 Now do a variation using POST to send arguments
 
-  $ hg serve --config experimental.httppostargs=true --config badserver.closeafterrecvbytes=361,330 -p $HGPORT -d --pid-file=hg.pid -E error.log
+  $ hg serve --config experimental.httppostargs=true --config badserver.closeafterrecvbytes=375,344 -p $HGPORT -d --pid-file=hg.pid -E error.log
   $ cat hg.pid > $DAEMON_PIDS
 
   $ hg clone http://localhost:$HGPORT/ clone
@@ -210,12 +210,12 b' Now do a variation using POST to send ar'
   $ killdaemons.py $DAEMON_PIDS
 
   $ cat error.log
-  readline(361 from 65537) -> (33) GET /?cmd=capabilities HTTP/1.1\r\n
-  readline(328 from -1) -> (27) Accept-Encoding: identity\r\n
-  readline(301 from -1) -> (19) vary: X-HgProto-1\r\n
-  readline(282 from -1) -> (27) x-hgproto-1: partial-pull\r\n
-  readline(255 from -1) -> (35) accept: application/mercurial-0.1\r\n
-  readline(220 from -1) -> (2?) host: localhost:$HGPORT\r\n (glob)
+  readline(375 from 65537) -> (33) GET /?cmd=capabilities HTTP/1.1\r\n
+  readline(342 from -1) -> (27) Accept-Encoding: identity\r\n
+  readline(315 from -1) -> (19) vary: X-HgProto-1\r\n
+  readline(296 from -1) -> (27) x-hgproto-1: partial-pull\r\n
+  readline(269 from -1) -> (35) accept: application/mercurial-0.1\r\n
+  readline(234 from -1) -> (2?) host: localhost:$HGPORT\r\n (glob)
   readline(* from -1) -> (49) user-agent: mercurial/proto-1.0 (Mercurial 4.2)\r\n (glob)
   readline(* from -1) -> (2) \r\n (glob)
   write(36) -> HTTP/1.1 200 Script output follows\r\n
@@ -225,17 +225,17 b' Now do a variation using POST to send ar'
   write(21) -> Content-Length: 449\r\n
   write(2) -> \r\n
   write(449) -> batch branchmap bundle2=HG20%0Abookmarks%0Achangegroup%3D01%2C02%0Adigests%3Dmd5%2Csha1%2Csha512%0Aerror%3Dabort%2Cunsupportedcontent%2Cpushraced%2Cpushkey%0Ahgtagsfnodes%0Alistkeys%0Apushkey%0Aremote-changegroup%3Dhttp%2Chttps%0Arev-branch-cache changegroupsubset compression=none getbundle httpheader=1024 httpmediatype=0.1rx,0.1tx,0.2tx httppostargs known lookup pushkey streamreqs=generaldelta,revlogv1 unbundle=HG10GZ,HG10BZ,HG10UN unbundlehash
-  readline\(14[67] from 65537\) -> \(2[67]\) POST /\?cmd=batch HTTP/1.1\\r\\n (re)
-  readline\(1(19|20) from -1\) -> \(27\) Accept-Encoding: identity\\r\\n (re)
-  readline(9? from -1) -> (41) content-type: application/mercurial-0.1\r\n (glob)
-  readline(5? from -1) -> (19) vary: X-HgProto-1\r\n (glob)
+  readline(1?? from 65537) -> (27) POST /?cmd=batch HTTP/1.1\r\n (glob)
+  readline(1?? from -1) -> (27) Accept-Encoding: identity\r\n (glob)
+  readline(1?? from -1) -> (41) content-type: application/mercurial-0.1\r\n (glob)
+  readline(6? from -1) -> (33) vary: X-HgArgs-Post,X-HgProto-1\r\n (glob)
   readline(3? from -1) -> (19) x-hgargs-post: 28\r\n (glob)
   readline(1? from -1) -> (1?) x-hgproto-1: * (glob)
   read limit reached; closing socket
-  readline(330 from 65537) -> (27) POST /?cmd=batch HTTP/1.1\r\n
-  readline(303 from -1) -> (27) Accept-Encoding: identity\r\n
-  readline(276 from -1) -> (41) content-type: application/mercurial-0.1\r\n
-  readline(235 from -1) -> (19) vary: X-HgProto-1\r\n
+  readline(344 from 65537) -> (27) POST /?cmd=batch HTTP/1.1\r\n
+  readline(317 from -1) -> (27) Accept-Encoding: identity\r\n
+  readline(290 from -1) -> (41) content-type: application/mercurial-0.1\r\n
+  readline(249 from -1) -> (33) vary: X-HgArgs-Post,X-HgProto-1\r\n
   readline(216 from -1) -> (19) x-hgargs-post: 28\r\n
   readline(197 from -1) -> (61) x-hgproto-1: 0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull\r\n
   readline(136 from -1) -> (35) accept: application/mercurial-0.1\r\n