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sshpeer: initial definition and implementation of new SSH protocol...
sshpeer: initial definition and implementation of new SSH protocol The existing SSH protocol has several design flaws. Future commits will elaborate on these flaws as new features are introduced to combat these flaws. For now, hopefully you can take me for my word that a ground up rewrite of the SSH protocol is needed. This commit lays the foundation for a new SSH protocol by defining a mechanism to upgrade the SSH transport channel away from the default (version 1) protocol to something modern (which we'll call "version 2" for now). This upgrade process is detailed in the internals documentation for the wire protocol. The gist of it is the client sends a request line preceding the "hello" command/line which basically says "I'm requesting an upgrade: here's what I support." If the server recognizes that line, it processes the upgrade request and the transport channel is switched to use the new version of the protocol. If not, it sends an empty response, which is how all Mercurial SSH servers from the beginning of time reacted to unknown commands. The upgrade request is effectively ignored and the client continues to use the existing version of the protocol as if nothing happened. The new version of the SSH protocol is completely identical to version 1 aside from the upgrade dance and the bytes that follow. The immediate bytes that follow the protocol switch are defined to be a length framed "capabilities: " line containing the remote's advertised capabilities. In reality, this looks very similar to what the "hello" response would look like. But it will evolve quickly. The methodology by which the protocol will evolve is important. I'm not going to introduce the new protocol all at once. That would likely lead to endless bike shedding and forward progress would stall. Instead, I intend to tricle out new features and diversions from the existing protocol in small, incremental changes. To support the gradual evolution of the protocol, the on-the-wire advertised protocol name contains an "exp" to denote "experimental" and a 4 digit field to capture the sub-version of the protocol. Whenever we make a BC change to the wire protocol, we can increment this version and lock out all older clients because it will appear as a completely different protocol version. This means we can incur as many breaking changes as we want. We don't have to commit to supporting any one feature or idea for a long period of time. We can even evolve the handshake mechanism, because that is defined as being an implementation detail of the negotiated protocol version! Hopefully this lowers the barrier to accepting changes to the protocol and for experimenting with "radical" ideas during its development. In core, sshpeer received most of the attention. We haven't even implemented the server bits for the new protocol in core yet. Instead, we add very primitive support to our test server, mainly just to exercise the added code paths in sshpeer. Differential Revision: https://phab.mercurial-scm.org/D2061 # no-check-commit because of required foo_bar naming

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r35994:48a3a928 default
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test-pull-branch.t
224 lines | 5.5 KiB | text/troff | Tads3Lexer
$ hg init t
$ cd t
$ echo 1 > foo
$ hg ci -Am1 # 0
adding foo
$ hg branch branchA
marked working directory as branch branchA
(branches are permanent and global, did you want a bookmark?)
$ echo a1 > foo
$ hg ci -ma1 # 1
$ cd ..
$ hg init tt
$ cd tt
$ hg pull ../t
pulling from ../t
requesting all changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
new changesets 495a0ec48aaf:50e089d141b7
(run 'hg update' to get a working copy)
$ hg up branchA
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd ../t
$ echo a2 > foo
$ hg ci -ma2 # 2
Create branch B:
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg branch branchB
marked working directory as branch branchB
$ echo b1 > foo
$ hg ci -mb1 # 3
$ cd ../tt
A new branch is there
$ hg pull -u ../t
pulling from ../t
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files (+1 heads)
new changesets 9f878dea0b96:5be59ce5067b
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
Develop both branches:
$ cd ../t
$ hg up branchA
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo a3 > foo
$ hg ci -ma3 # 4
$ hg up branchB
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo b2 > foo
$ hg ci -mb2 # 5
$ cd ../tt
Should succeed, no new heads:
$ hg pull -u ../t
pulling from ../t
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
new changesets 7c8fe7e20c32:453e93fa00a5
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
Add a head on other branch:
$ cd ../t
$ hg up branchA
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo a4 > foo
$ hg ci -ma4 # 6
$ hg up branchB
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo b3.1 > foo
$ hg ci -m b3.1 # 7
$ hg up 5
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo b3.2 > foo
$ hg ci -m b3.2 # 8
created new head
$ cd ../tt
Should succeed because there is only one head on our branch:
$ hg pull -u ../t
pulling from ../t
searching for changes
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 1 files (+1 heads)
new changesets da3a8a0161c6:b61cab8fe4e8
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd ../t
$ hg up -C branchA
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo a5.1 > foo
$ hg ci -ma5.1 # 9
$ hg up 6
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo a5.2 > foo
$ hg ci -ma5.2 # 10
created new head
$ hg up 7
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo b4.1 > foo
$ hg ci -m b4.1 # 11
$ hg up -C 8
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo b4.2 > foo
$ hg ci -m b4.2 # 12
$ cd ../tt
$ hg pull -u ../t
pulling from ../t
searching for changes
adding changesets
adding manifests
adding file changes
added 4 changesets with 4 changes to 1 files (+1 heads)
new changesets 0c4d148ae29e:ecfc3f4a6fd9
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
updated to "d740e1a584e7: a5.2"
1 other heads for branch "branchA"
Make changes on new branch on tt
$ hg up 6
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg branch branchC
marked working directory as branch branchC
$ echo b1 > bar
$ hg ci -Am "commit on branchC on tt"
adding bar
Make changes on default branch on t
$ cd ../t
$ hg up -C default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo a1 > bar
$ hg ci -Am "commit on default on t"
adding bar
Pull branchC from tt
$ hg pull ../tt
pulling from ../tt
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
new changesets 7d8ffa4c0b22
(run 'hg heads' to see heads)
Make changes on default and branchC on tt
$ cd ../tt
$ hg pull ../t
pulling from ../t
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
new changesets 2b94b54b6b5f
(run 'hg heads' to see heads)
$ hg up -C default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo a1 > bar1
$ hg ci -Am "commit on default on tt"
adding bar1
$ hg up branchC
2 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo a1 > bar2
$ hg ci -Am "commit on branchC on tt"
adding bar2
Make changes on default and branchC on t
$ cd ../t
$ hg up default
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo a1 > bar3
$ hg ci -Am "commit on default on t"
adding bar3
$ hg up branchC
2 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo a1 > bar4
$ hg ci -Am "commit on branchC on tt"
adding bar4
Pull from tt
$ hg pull ../tt
pulling from ../tt
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 2 files (+2 heads)
new changesets eed40c14b407:e634733b0309
(run 'hg heads .' to see heads, 'hg merge' to merge)
$ cd ..