wireproto: define and implement HTTP handshake to upgrade protocol
When clients connect to repositories over HTTP, they issue a request
to the well-known URL "?cmd=capabilities" to fetch the repository
capabilities. This is the handshake portion of the HTTP protocol.
This commit defines a mechanism to use that HTTP request to return
information about modern server features.
If a client sends an X-HgUpgrade-* header containing a list of
client-supported API names, the server responds with a response
containing information about available services. This includes
the normal capabilities string. So if the server doesn't support
any newer services, the client can easily fall back.
By advertising supported services from clients, server operators
can see and log what client support exists in the wild. This will
also help with debugging.
The response contains the base path to API services. We know there
are potential issues with the <repo>/api/ URL space conflicting with
hgwebdir and subrepos. By making the API URL dynamic from the
perspective of the client, the URL for APIs is not subject to backwards
compatibility concerns - at least as long as a ?cmd=capabilities request
is made.
We've also defined the ``cbor`` client capability for the X-HgProto-*
header. This MUST be sent in order to get the modern response from
"?cmd=capabilities". During implementation, I initially always sent
an application/mercurial-cbor response. However, the handshake
mechanism will be more future compatible if the client is in charge
of which formats to request. We already perform content negotiation
from X-HgProto-*, so keying off this for the capabilities response
feels appropriate.
In addition, I initially used application/cbor. However, it is
conceivable that a non-Mercurial server could serve application/cbor.
To rule out this possibility, I've invented a new media type that
is Mercurial specific and can't be confused for generic CBOR.
Differential Revision: https://phab.mercurial-scm.org/D3242
#testcases lfsremote-on lfsremote-off
#require serve no-reposimplestore
This test splits `hg serve` with and without using the extension into separate
tests cases. The tests are broken down as follows, where "LFS"/"No-LFS"
indicates whether or not there are commits that use an LFS file, and "D"/"E"
indicates whether or not the extension is loaded. The "X" cases are not tested
individually, because the lfs requirement causes the process to bail early if
the extension is disabled.
. Server
.
. No-LFS LFS
. +----------------------------+
. | || D | E | D | E |
. |---++=======================|
. C | D || N/A | #1 | X | #4 |
. l No +---++-----------------------|
. i LFS | E || #2 | #2 | X | #5 |
. e +---++-----------------------|
. n | D || X | X | X | X |
. t LFS |---++-----------------------|
. | E || #3 | #3 | X | #6 |
. |---++-----------------------+
$ hg init server
$ SERVER_REQUIRES="$TESTTMP/server/.hg/requires"
Skip the experimental.changegroup3=True config. Failure to agree on this comes
first, and causes a "ValueError: no common changegroup version" or "abort:
HTTP Error 500: Internal Server Error", if the extension is only loaded on one
side. If that *is* enabled, the subsequent failure is "abort: missing processor
for flag '0x2000'!" if the extension is only loaded on one side (possibly also
masked by the Internal Server Error message).
$ cat >> $HGRCPATH <<EOF
> [lfs]
> usercache = null://
> threshold=10
> [web]
> allow_push=*
> push_ssl=False
> EOF
#if lfsremote-on
$ hg --config extensions.lfs= -R server \
> serve -p $HGPORT -d --pid-file=hg.pid --errorlog=$TESTTMP/errors.log
#else
$ hg --config extensions.lfs=! -R server \
> serve -p $HGPORT -d --pid-file=hg.pid --errorlog=$TESTTMP/errors.log
#endif
$ cat hg.pid >> $DAEMON_PIDS
$ hg clone -q http://localhost:$HGPORT client
$ grep 'lfs' client/.hg/requires $SERVER_REQUIRES
[1]
--------------------------------------------------------------------------------
Case #1: client with non-lfs content and the extension disabled; server with
non-lfs content, and the extension enabled.
$ cd client
$ echo 'non-lfs' > nonlfs.txt
$ hg ci -Aqm 'non-lfs'
$ grep 'lfs' .hg/requires $SERVER_REQUIRES
[1]
#if lfsremote-on
$ hg push -q
$ grep 'lfs' .hg/requires $SERVER_REQUIRES
[1]
$ hg clone -q http://localhost:$HGPORT $TESTTMP/client1_clone
$ grep 'lfs' $TESTTMP/client1_clone/.hg/requires $SERVER_REQUIRES
[1]
$ hg init $TESTTMP/client1_pull
$ hg -R $TESTTMP/client1_pull pull -q http://localhost:$HGPORT
$ grep 'lfs' $TESTTMP/client1_pull/.hg/requires $SERVER_REQUIRES
[1]
$ hg identify http://localhost:$HGPORT
d437e1d24fbd
#endif
--------------------------------------------------------------------------------
Case #2: client with non-lfs content and the extension enabled; server with
non-lfs content, and the extension state controlled by #testcases.
$ cat >> $HGRCPATH <<EOF
> [extensions]
> lfs =
> EOF
$ echo 'non-lfs' > nonlfs2.txt
$ hg ci -Aqm 'non-lfs file with lfs client'
Since no lfs content has been added yet, the push is allowed, even when the
extension is not enabled remotely.
$ hg push -q
$ grep 'lfs' .hg/requires $SERVER_REQUIRES
[1]
$ hg clone -q http://localhost:$HGPORT $TESTTMP/client2_clone
$ grep 'lfs' $TESTTMP/client2_clone/.hg/requires $SERVER_REQUIRES
[1]
$ hg init $TESTTMP/client2_pull
$ hg -R $TESTTMP/client2_pull pull -q http://localhost:$HGPORT
$ grep 'lfs' $TESTTMP/client2_pull/.hg/requires $SERVER_REQUIRES
[1]
$ hg identify http://localhost:$HGPORT
1477875038c6
--------------------------------------------------------------------------------
Case #3: client with lfs content and the extension enabled; server with
non-lfs content, and the extension state controlled by #testcases. The server
should have an 'lfs' requirement after it picks up its first commit with a blob.
$ echo 'this is a big lfs file' > lfs.bin
$ hg ci -Aqm 'lfs'
$ grep 'lfs' .hg/requires $SERVER_REQUIRES
.hg/requires:lfs
#if lfsremote-off
$ hg push -q
abort: required features are not supported in the destination: lfs
(enable the lfs extension on the server)
[255]
#else
$ hg push -q
#endif
$ grep 'lfs' .hg/requires $SERVER_REQUIRES
.hg/requires:lfs
$TESTTMP/server/.hg/requires:lfs (lfsremote-on !)
$ hg clone -q http://localhost:$HGPORT $TESTTMP/client3_clone
$ grep 'lfs' $TESTTMP/client3_clone/.hg/requires $SERVER_REQUIRES || true
$TESTTMP/client3_clone/.hg/requires:lfs (lfsremote-on !)
$TESTTMP/server/.hg/requires:lfs (lfsremote-on !)
$ hg init $TESTTMP/client3_pull
$ hg -R $TESTTMP/client3_pull pull -q http://localhost:$HGPORT
$ grep 'lfs' $TESTTMP/client3_pull/.hg/requires $SERVER_REQUIRES || true
$TESTTMP/client3_pull/.hg/requires:lfs (lfsremote-on !)
$TESTTMP/server/.hg/requires:lfs (lfsremote-on !)
The difference here is the push failed above when the extension isn't
enabled on the server.
$ hg identify http://localhost:$HGPORT
8374dc4052cb (lfsremote-on !)
1477875038c6 (lfsremote-off !)
Don't bother testing the lfsremote-off cases- the server won't be able
to launch if there's lfs content and the extension is disabled.
#if lfsremote-on
--------------------------------------------------------------------------------
Case #4: client with non-lfs content and the extension disabled; server with
lfs content, and the extension enabled.
$ cat >> $HGRCPATH <<EOF
> [extensions]
> lfs = !
> EOF
$ hg init $TESTTMP/client4
$ cd $TESTTMP/client4
$ cat >> .hg/hgrc <<EOF
> [paths]
> default = http://localhost:$HGPORT
> EOF
$ echo 'non-lfs' > nonlfs2.txt
$ hg ci -Aqm 'non-lfs'
$ grep 'lfs' .hg/requires $SERVER_REQUIRES
$TESTTMP/server/.hg/requires:lfs
$ hg push -q --force
warning: repository is unrelated
$ grep 'lfs' .hg/requires $SERVER_REQUIRES
$TESTTMP/server/.hg/requires:lfs
TODO: fail more gracefully.
$ hg clone -q http://localhost:$HGPORT $TESTTMP/client4_clone
abort: HTTP Error 500: Internal Server Error
[255]
$ grep 'lfs' $TESTTMP/client4_clone/.hg/requires $SERVER_REQUIRES
grep: $TESTTMP/client4_clone/.hg/requires: $ENOENT$
$TESTTMP/server/.hg/requires:lfs
[2]
TODO: fail more gracefully.
$ hg init $TESTTMP/client4_pull
$ hg -R $TESTTMP/client4_pull pull -q http://localhost:$HGPORT
abort: HTTP Error 500: Internal Server Error
[255]
$ grep 'lfs' $TESTTMP/client4_pull/.hg/requires $SERVER_REQUIRES
$TESTTMP/server/.hg/requires:lfs
$ hg identify http://localhost:$HGPORT
03b080fa9d93
--------------------------------------------------------------------------------
Case #5: client with non-lfs content and the extension enabled; server with
lfs content, and the extension enabled.
$ cat >> $HGRCPATH <<EOF
> [extensions]
> lfs =
> EOF
$ echo 'non-lfs' > nonlfs3.txt
$ hg ci -Aqm 'non-lfs file with lfs client'
$ hg push -q
$ grep 'lfs' .hg/requires $SERVER_REQUIRES
$TESTTMP/server/.hg/requires:lfs
$ hg clone -q http://localhost:$HGPORT $TESTTMP/client5_clone
$ grep 'lfs' $TESTTMP/client5_clone/.hg/requires $SERVER_REQUIRES
$TESTTMP/client5_clone/.hg/requires:lfs
$TESTTMP/server/.hg/requires:lfs
$ hg init $TESTTMP/client5_pull
$ hg -R $TESTTMP/client5_pull pull -q http://localhost:$HGPORT
$ grep 'lfs' $TESTTMP/client5_pull/.hg/requires $SERVER_REQUIRES
$TESTTMP/client5_pull/.hg/requires:lfs
$TESTTMP/server/.hg/requires:lfs
$ hg identify http://localhost:$HGPORT
c729025cc5e3
--------------------------------------------------------------------------------
Case #6: client with lfs content and the extension enabled; server with
lfs content, and the extension enabled.
$ echo 'this is another lfs file' > lfs2.txt
$ hg ci -Aqm 'lfs file with lfs client'
$ hg push -q
$ grep 'lfs' .hg/requires $SERVER_REQUIRES
.hg/requires:lfs
$TESTTMP/server/.hg/requires:lfs
$ hg clone -q http://localhost:$HGPORT $TESTTMP/client6_clone
$ grep 'lfs' $TESTTMP/client6_clone/.hg/requires $SERVER_REQUIRES
$TESTTMP/client6_clone/.hg/requires:lfs
$TESTTMP/server/.hg/requires:lfs
$ hg init $TESTTMP/client6_pull
$ hg -R $TESTTMP/client6_pull pull -q http://localhost:$HGPORT
$ grep 'lfs' $TESTTMP/client6_pull/.hg/requires $SERVER_REQUIRES
$TESTTMP/client6_pull/.hg/requires:lfs
$TESTTMP/server/.hg/requires:lfs
$ hg identify http://localhost:$HGPORT
d3b84d50eacb
--------------------------------------------------------------------------------
Misc: process dies early if a requirement exists and the extension is disabled
$ hg --config extensions.lfs=! summary
abort: repository requires features unknown to this Mercurial: lfs!
(see https://mercurial-scm.org/wiki/MissingRequirement for more information)
[255]
#endif
$ $PYTHON $TESTDIR/killdaemons.py $DAEMON_PIDS
#if lfsremote-on
$ cat $TESTTMP/errors.log | grep '^[A-Z]'
Traceback (most recent call last):
ValueError: no common changegroup version
Traceback (most recent call last):
ValueError: no common changegroup version
#else
$ cat $TESTTMP/errors.log
#endif