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
#require killdaemons
Tests discovery against servers without getbundle support:
$ cat >> $HGRCPATH <<EOF
> [ui]
> logtemplate="{rev} {node|short}: {desc} {branches}\n"
> EOF
$ cp $HGRCPATH $HGRCPATH-withcap
$ CAP="getbundle known changegroupsubset bundle2"
$ . "$TESTDIR/notcapable"
$ cp $HGRCPATH $HGRCPATH-nocap
$ cp $HGRCPATH-withcap $HGRCPATH
Prep for test server without branchmap support
$ CAP="branchmap"
$ . "$TESTDIR/notcapable"
$ cp $HGRCPATH $HGRCPATH-nocap-branchmap
$ cp $HGRCPATH-withcap $HGRCPATH
Setup HTTP server control:
$ remote=http://localhost:$HGPORT/
$ export remote
$ tstart() {
> echo '[web]' > $1/.hg/hgrc
> echo 'push_ssl = false' >> $1/.hg/hgrc
> echo 'allow_push = *' >> $1/.hg/hgrc
> cp $HGRCPATH-nocap $HGRCPATH
> hg serve -R $1 -p $HGPORT -d --pid-file=hg.pid -E errors.log
> cat hg.pid >> $DAEMON_PIDS
> }
$ tstop() {
> killdaemons.py
> cp $HGRCPATH-withcap $HGRCPATH
> }
Both are empty:
$ hg init empty1
$ hg init empty2
$ tstart empty2
$ hg incoming -R empty1 $remote
comparing with http://localhost:$HGPORT/
no changes found
[1]
$ hg outgoing -R empty1 $remote
comparing with http://localhost:$HGPORT/
no changes found
[1]
$ hg pull -R empty1 $remote
pulling from http://localhost:$HGPORT/
no changes found
$ hg push -R empty1 $remote
pushing to http://localhost:$HGPORT/
no changes found
[1]
$ tstop
Base repo:
$ hg init main
$ cd main
$ hg debugbuilddag -mo '+2:tbase @name1 +3:thead1 <tbase @name2 +4:thead2 @both /thead1 +2:tmaintip'
$ hg log -G
o 11 a19bfa7e7328: r11 both
|
o 10 8b6bad1512e1: r10 both
|
o 9 025829e08038: r9 both
|\
| o 8 d8f638ac69e9: r8 name2
| |
| o 7 b6b4d315a2ac: r7 name2
| |
| o 6 6c6f5d5f3c11: r6 name2
| |
| o 5 70314b29987d: r5 name2
| |
o | 4 e71dbbc70e03: r4 name1
| |
o | 3 2c8d5d5ec612: r3 name1
| |
o | 2 a7892891da29: r2 name1
|/
o 1 0019a3b924fd: r1
|
o 0 d57206cc072a: r0
$ cd ..
$ tstart main
Full clone:
$ hg clone main full
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd full
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ hg pull $remote
pulling from http://localhost:$HGPORT/
searching for changes
no changes found
$ hg push $remote
pushing to http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ cd ..
Local is empty:
$ cd empty1
$ hg incoming $remote --rev name1
comparing with http://localhost:$HGPORT/
abort: cannot look up remote changes; remote repository does not support the 'changegroupsubset' capability!
[255]
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
0 d57206cc072a: r0
1 0019a3b924fd: r1
2 a7892891da29: r2 name1
3 2c8d5d5ec612: r3 name1
4 e71dbbc70e03: r4 name1
5 70314b29987d: r5 name2
6 6c6f5d5f3c11: r6 name2
7 b6b4d315a2ac: r7 name2
8 d8f638ac69e9: r8 name2
9 025829e08038: r9 both
10 8b6bad1512e1: r10 both
11 a19bfa7e7328: r11 both
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
no changes found
[1]
$ hg push $remote
pushing to http://localhost:$HGPORT/
no changes found
[1]
$ hg pull $remote
pulling from http://localhost:$HGPORT/
requesting all changes
adding changesets
adding manifests
adding file changes
added 12 changesets with 24 changes to 2 files
new changesets d57206cc072a:a19bfa7e7328
(run 'hg update' to get a working copy)
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ cd ..
Local is subset:
$ cp $HGRCPATH-withcap $HGRCPATH
$ hg clone main subset --rev name2 ; cd subset
adding changesets
adding manifests
adding file changes
added 6 changesets with 12 changes to 2 files
new changesets d57206cc072a:d8f638ac69e9
updating to branch name2
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cp $HGRCPATH-nocap $HGRCPATH
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
searching for changes
6 a7892891da29: r2 name1
7 2c8d5d5ec612: r3 name1
8 e71dbbc70e03: r4 name1
9 025829e08038: r9 both
10 8b6bad1512e1: r10 both
11 a19bfa7e7328: r11 both
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ hg push $remote
pushing to http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ hg pull $remote
pulling from http://localhost:$HGPORT/
searching for changes
adding changesets
adding manifests
adding file changes
added 6 changesets with 12 changes to 2 files
new changesets a7892891da29:a19bfa7e7328
(run 'hg update' to get a working copy)
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ cd ..
Remote is empty:
$ tstop ; tstart empty2
$ cd main
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
0 d57206cc072a: r0
1 0019a3b924fd: r1
2 a7892891da29: r2 name1
3 2c8d5d5ec612: r3 name1
4 e71dbbc70e03: r4 name1
5 70314b29987d: r5 name2
6 6c6f5d5f3c11: r6 name2
7 b6b4d315a2ac: r7 name2
8 d8f638ac69e9: r8 name2
9 025829e08038: r9 both
10 8b6bad1512e1: r10 both
11 a19bfa7e7328: r11 both
$ hg pull $remote
pulling from http://localhost:$HGPORT/
searching for changes
no changes found
$ hg push $remote
pushing to http://localhost:$HGPORT/
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 12 changesets with 24 changes to 2 files
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ cd ..
Local is superset:
$ tstop
$ hg clone main subset2 --rev name2
adding changesets
adding manifests
adding file changes
added 6 changesets with 12 changes to 2 files
new changesets d57206cc072a:d8f638ac69e9
updating to branch name2
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ tstart subset2
$ cd main
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
2 a7892891da29: r2 name1
3 2c8d5d5ec612: r3 name1
4 e71dbbc70e03: r4 name1
9 025829e08038: r9 both
10 8b6bad1512e1: r10 both
11 a19bfa7e7328: r11 both
$ hg pull $remote
pulling from http://localhost:$HGPORT/
searching for changes
no changes found
$ hg push $remote
pushing to http://localhost:$HGPORT/
searching for changes
abort: push creates new remote branches: both, name1!
(use 'hg push --new-branch' to create new remote branches)
[255]
$ hg push $remote --new-branch
pushing to http://localhost:$HGPORT/
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 6 changesets with 12 changes to 2 files
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ cd ..
Partial pull:
$ tstop ; tstart main
$ hg clone $remote partial --rev name2
abort: partial pull cannot be done because other repository doesn't support changegroupsubset.
[255]
$ hg init partial; cd partial
$ hg incoming $remote --rev name2
comparing with http://localhost:$HGPORT/
abort: cannot look up remote changes; remote repository does not support the 'changegroupsubset' capability!
[255]
$ hg pull $remote --rev name2
pulling from http://localhost:$HGPORT/
abort: partial pull cannot be done because other repository doesn't support changegroupsubset.
[255]
$ cd ..
$ tstop
Exercise pushing to server without branchmap capability
$ cp $HGRCPATH-nocap-branchmap $HGRCPATH-nocap
$ hg init rlocal
$ cd rlocal
$ echo A > A
$ hg ci -Am A
adding A
$ cd ..
$ hg clone rlocal rremote
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd rlocal
$ echo B > B
$ hg ci -Am B
adding B
$ cd ..
$ tstart rremote
$ cd rlocal
$ hg incoming $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
1 27547f69f254: B
$ hg pull $remote
pulling from http://localhost:$HGPORT/
searching for changes
no changes found
$ hg push $remote
pushing to http://localhost:$HGPORT/
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
$ hg outgoing $remote
comparing with http://localhost:$HGPORT/
searching for changes
no changes found
[1]
$ cd ..
$ tstop