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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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test-bundle-type.t
228 lines | 5.0 KiB | text/troff | Tads3Lexer
$ cat << EOF >> $HGRCPATH
> [format]
> usegeneraldelta=yes
> EOF
bundle w/o type option
$ hg init t1
$ hg init t2
$ cd t1
$ echo blablablablabla > file.txt
$ hg ci -Ama
adding file.txt
$ hg log | grep summary
summary: a
$ hg bundle ../b1 ../t2
searching for changes
1 changesets found
$ cd ../t2
$ hg pull ../b1
pulling from ../b1
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets c35a0f9217e6
(run 'hg update' to get a working copy)
$ hg up
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg log | grep summary
summary: a
$ cd ..
Unknown compression type is rejected
$ hg init t3
$ cd t3
$ hg -q pull ../b1
$ hg bundle -a -t unknown out.hg
abort: unknown is not a recognized bundle specification
(see 'hg help bundlespec' for supported values for --type)
[255]
$ hg bundle -a -t unknown-v2 out.hg
abort: unknown compression is not supported
(see 'hg help bundlespec' for supported values for --type)
[255]
$ cd ..
test bundle types
$ testbundle() {
> echo % test bundle type $1
> hg init t$1
> cd t1
> hg bundle -t $1 ../b$1 ../t$1
> f -q -B6 -D ../b$1; echo
> cd ../t$1
> hg debugbundle ../b$1
> hg debugbundle --spec ../b$1
> echo
> cd ..
> }
$ for t in "None" "bzip2" "gzip" "none-v2" "v2" "v1" "gzip-v1"; do
> testbundle $t
> done
% test bundle type None
searching for changes
1 changesets found
HG20\x00\x00 (esc)
Stream params: {}
changegroup -- {nbchanges: 1, version: 02}
c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
none-v2
% test bundle type bzip2
searching for changes
1 changesets found
HG20\x00\x00 (esc)
Stream params: {Compression: BZ}
changegroup -- {nbchanges: 1, version: 02}
c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
bzip2-v2
% test bundle type gzip
searching for changes
1 changesets found
HG20\x00\x00 (esc)
Stream params: {Compression: GZ}
changegroup -- {nbchanges: 1, version: 02}
c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
gzip-v2
% test bundle type none-v2
searching for changes
1 changesets found
HG20\x00\x00 (esc)
Stream params: {}
changegroup -- {nbchanges: 1, version: 02}
c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
none-v2
% test bundle type v2
searching for changes
1 changesets found
HG20\x00\x00 (esc)
Stream params: {Compression: BZ}
changegroup -- {nbchanges: 1, version: 02}
c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
bzip2-v2
% test bundle type v1
searching for changes
1 changesets found
HG10BZ
c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
bzip2-v1
% test bundle type gzip-v1
searching for changes
1 changesets found
HG10GZ
c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
gzip-v1
Compression level can be adjusted for bundle2 bundles
$ hg init test-complevel
$ cd test-complevel
$ cat > file0 << EOF
> this is a file
> with some text
> and some more text
> and other content
> EOF
$ cat > file1 << EOF
> this is another file
> with some other content
> and repeated, repeated, repeated, repeated content
> EOF
$ hg -q commit -A -m initial
$ hg bundle -a -t gzip-v2 gzip-v2.hg
1 changesets found
$ f --size gzip-v2.hg
gzip-v2.hg: size=427
$ hg --config experimental.bundlecomplevel=1 bundle -a -t gzip-v2 gzip-v2-level1.hg
1 changesets found
$ f --size gzip-v2-level1.hg
gzip-v2-level1.hg: size=435
$ cd ..
#if zstd
$ for t in "zstd" "zstd-v2"; do
> testbundle $t
> done
% test bundle type zstd
searching for changes
1 changesets found
HG20\x00\x00 (esc)
Stream params: {Compression: ZS}
changegroup -- {nbchanges: 1, version: 02}
c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
zstd-v2
% test bundle type zstd-v2
searching for changes
1 changesets found
HG20\x00\x00 (esc)
Stream params: {Compression: ZS}
changegroup -- {nbchanges: 1, version: 02}
c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
zstd-v2
Explicit request for zstd on non-generaldelta repos
$ hg --config format.usegeneraldelta=false init nogd
$ hg -q -R nogd pull t1
$ hg -R nogd bundle -a -t zstd nogd-zstd
1 changesets found
zstd-v1 always fails
$ hg -R tzstd bundle -a -t zstd-v1 zstd-v1
abort: compression engine zstd is not supported on v1 bundles
(see 'hg help bundlespec' for supported values for --type)
[255]
#else
zstd is a valid engine but isn't available
$ hg -R t1 bundle -a -t zstd irrelevant.hg
abort: compression engine zstd could not be loaded
[255]
#endif
test garbage file
$ echo garbage > bgarbage
$ hg init tgarbage
$ cd tgarbage
$ hg pull ../bgarbage
pulling from ../bgarbage
abort: ../bgarbage: not a Mercurial bundle
[255]
$ cd ..
test invalid bundle type
$ cd t1
$ hg bundle -a -t garbage ../bgarbage
abort: garbage is not a recognized bundle specification
(see 'hg help bundlespec' for supported values for --type)
[255]
$ cd ..