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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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r30888:561a019c stable
r35994:48a3a928 default
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test-convert-tla.t
134 lines | 4.0 KiB | text/troff | Tads3Lexer
#require tla symlink
$ tla my-id "mercurial <mercurial@mercurial-scm.org>"
$ echo "[extensions]" >> $HGRCPATH
$ echo "convert=" >> $HGRCPATH
create tla archive
$ tla make-archive tla@mercurial--convert `pwd`/hg-test-convert-tla
initialize tla repo
$ mkdir tla-repo
$ cd tla-repo/
$ tla init-tree tla@mercurial--convert/tla--test--0
$ tla import
* creating version tla@mercurial--convert/tla--test--0
* imported tla@mercurial--convert/tla--test--0
create initial files
$ echo 'this is a file' > a
$ tla add a
$ mkdir src
$ tla add src
$ cd src
$ dd count=1 if=/dev/zero of=b > /dev/null 2> /dev/null
$ tla add b
$ tla commit -s "added a file, src and src/b (binary)"
A/ .arch-ids
A/ src
A/ src/.arch-ids
A .arch-ids/a.id
A a
A src/.arch-ids/=id
A src/.arch-ids/b.id
A src/b
* update pristine tree (tla@mercurial--convert/tla--test--0--base-0 => tla--test--0--patch-1)
* committed tla@mercurial--convert/tla--test--0--patch-1
create link file and modify a
$ ln -s ../a a-link
$ tla add a-link
$ echo 'this a modification to a' >> ../a
$ tla commit -s "added link to a and modify a"
A src/.arch-ids/a-link.id
A src/a-link
M a
* update pristine tree (tla@mercurial--convert/tla--test--0--patch-1 => tla--test--0--patch-2)
* committed tla@mercurial--convert/tla--test--0--patch-2
create second link and modify b
$ ln -s ../a a-link-2
$ tla add a-link-2
$ dd count=1 seek=1 if=/dev/zero of=b > /dev/null 2> /dev/null
$ tla commit -s "added second link and modify b"
A src/.arch-ids/a-link-2.id
A src/a-link-2
Mb src/b
* update pristine tree (tla@mercurial--convert/tla--test--0--patch-2 => tla--test--0--patch-3)
* committed tla@mercurial--convert/tla--test--0--patch-3
b file to link and a-link-2 to regular file
$ rm -f a-link-2
$ echo 'this is now a regular file' > a-link-2
$ ln -sf ../a b
$ tla commit -s "file to link and link to file test"
fl src/b
lf src/a-link-2
* update pristine tree (tla@mercurial--convert/tla--test--0--patch-3 => tla--test--0--patch-4)
* committed tla@mercurial--convert/tla--test--0--patch-4
move a-link-2 file and src directory
$ cd ..
$ tla mv src/a-link-2 c
$ tla mv src test
$ tla commit -s "move and rename a-link-2 file and src directory"
D/ src/.arch-ids
A/ test/.arch-ids
/> src test
=> src/.arch-ids/a-link-2.id .arch-ids/c.id
=> src/a-link-2 c
=> src/.arch-ids/=id test/.arch-ids/=id
=> src/.arch-ids/a-link.id test/.arch-ids/a-link.id
=> src/.arch-ids/b.id test/.arch-ids/b.id
* update pristine tree (tla@mercurial--convert/tla--test--0--patch-4 => tla--test--0--patch-5)
* committed tla@mercurial--convert/tla--test--0--patch-5
$ cd ..
converting tla repo to Mercurial
$ hg convert tla-repo tla-repo-hg
initializing destination tla-repo-hg repository
analyzing tree version tla@mercurial--convert/tla--test--0...
scanning source...
sorting...
converting...
5 initial import
4 added a file, src and src/b (binary)
3 added link to a and modify a
2 added second link and modify b
1 file to link and link to file test
0 move and rename a-link-2 file and src directory
$ tla register-archive -d tla@mercurial--convert
$ glog()
> {
> hg log -G --template '{rev} "{desc|firstline}" files: {files}\n' "$@"
> }
show graph log
$ glog -R tla-repo-hg
o 5 "move and rename a-link-2 file and src directory" files: c src/a-link src/a-link-2 src/b test/a-link test/b
|
o 4 "file to link and link to file test" files: src/a-link-2 src/b
|
o 3 "added second link and modify b" files: src/a-link-2 src/b
|
o 2 "added link to a and modify a" files: a src/a-link
|
o 1 "added a file, src and src/b (binary)" files: a src/b
|
o 0 "initial import" files:
$ hg up -q -R tla-repo-hg
$ hg -R tla-repo-hg manifest --debug
c4072c4b72e1cabace081888efa148ee80ca3cbb 644 a
0201ac32a3a8e86e303dff60366382a54b48a72e 644 c
c0067ba5ff0b7c9a3eb17270839d04614c435623 644 @ test/a-link
375f4263d86feacdea7e3c27100abd1560f2a973 644 @ test/b