view tests/test-dispatch.t @ 35884:197d10e157ce

httppeer: remove support for connecting to <0.9.1 servers (BC)

Previously, HTTP wire protocol clients would attempt a
"capabilities" wire protocol command. If that failed, they would
fall back to issuing a "between" command.

The "capabilities" command was added in Mercurial 0.9.1 (released
July 2006). The "between" command has been present for as long as
the wire protocol has existed. So if the "between" command failed,
it was safe to assume that the remote could not speak any version
of the Mercurial wire protocol.

The "between" fallback was added in 395a84f78736 in 2011. Before that
changeset, Mercurial would *always* issue the "between" command and
would issue "capabilities" if capabilities were requested. At that time,
many connections would issue "capabilities" eventually, so it was
decided to issue "capabilities" by default and fall back to "between"
if that failed. This saved a round trip when connecting to modern
servers while still preserving compatibility with legacy servers.

Fast forward ~7 years. Mercurial servers supporting "capabilities"
have been around for over a decade. If modern clients are
connecting to <0.9.1 servers, they are getting a bad experience.
They may even be getting bad data (an old server is vulnerable to
numerous security issues and could have been p0wned, leading to a
Mercurial repository serving backdoors or other badness).

In addition, the fallback can harm experience for modern servers.
If a client experiences an intermittent HTTP request failure (due to
bad network, etc) and falls back to a "between" that works, it would
assume an empty capability set and would attempt to communicate with
the repository using a very ancient wire protocol. Auditing HTTP logs
for hg.mozilla.org, I did find a handful of requests for the
null range of the "between" command. However, requests can be days
apart. And when I do see requests, they come in batches. Those
batches seem to correlate to spikes of HTTP 500 or other
server/network events. So I think these requests are fallbacks from
failed "capabilities" requests and not from old clients.

If you need even more evidence to discontinue support, apparently
we have no test coverage for communicating with servers not
supporting "capabilities." I know this because all tests pass
with the "between" fallback removed.

Finally, server-side support for <0.9.1 pushing (the "addchangegroup"
wire protocol command along with locking-related commands) was dropped
from the HTTP client in fda0867cfe03 in 2017 and the SSH client in
9f6e0e7ef828 in 2015.

I think this all adds up to enough justification for removing client
support for communicating with servers not supporting "capabilities."
So this commit removes that fallback.

Differential Revision: https://phab.mercurial-scm.org/D2001

test command parsing and dispatch

  $ hg init a
  $ cd a

Redundant options used to crash (issue436):
  $ hg -v log -v
  $ hg -v log -v x

  $ echo a > a
  $ hg ci -Ama
  adding a

Missing arg:

  $ hg cat
  hg cat: invalid arguments
  hg cat [OPTION]... FILE...
  
  output the current or given revision of files
  
  options ([+] can be repeated):
  
   -o --output FORMAT       print output to file with formatted name
   -r --rev REV             print the given revision
      --decode              apply any matching decode filter
   -I --include PATTERN [+] include names matching the given patterns
   -X --exclude PATTERN [+] exclude names matching the given patterns
  
  (use 'hg cat -h' to show more help)
  [255]

Missing parameter for early option:

  $ hg log -R 2>&1 | grep 'hg log'
  hg log: option -R requires argument
  hg log [OPTION]... [FILE]
  (use 'hg log -h' to show more help)

"--" may be an option value:

  $ hg -R -- log
  abort: repository -- not found!
  [255]
  $ hg log -R --
  abort: repository -- not found!
  [255]
  $ hg log -T --
  -- (no-eol)
  $ hg log -T -- -k nomatch

Parsing of early options should stop at "--":

  $ hg cat -- --config=hooks.pre-cat=false
  --config=hooks.pre-cat=false: no such file in rev cb9a9f314b8b
  [1]
  $ hg cat -- --debugger
  --debugger: no such file in rev cb9a9f314b8b
  [1]

Unparsable form of early options:

  $ hg cat --debugg
  abort: option --debugger may not be abbreviated!
  [255]

Parsing failure of early options should be detected before executing the
command:

  $ hg log -b '--config=hooks.pre-log=false' default
  abort: option --config may not be abbreviated!
  [255]
  $ hg log -b -R. default
  abort: option -R has to be separated from other options (e.g. not -qR) and --repository may only be abbreviated as --repo!
  [255]
  $ hg log --cwd .. -b --cwd=. default
  abort: option --cwd may not be abbreviated!
  [255]

However, we can't prevent it from loading extensions and configs:

  $ cat <<EOF > bad.py
  > raise Exception('bad')
  > EOF
  $ hg log -b '--config=extensions.bad=bad.py' default
  *** failed to import extension bad from bad.py: bad
  abort: option --config may not be abbreviated!
  [255]

  $ mkdir -p badrepo/.hg
  $ echo 'invalid-syntax' > badrepo/.hg/hgrc
  $ hg log -b -Rbadrepo default
  hg: parse error at badrepo/.hg/hgrc:1: invalid-syntax
  [255]

  $ hg log -b --cwd=inexistent default
  abort: $ENOENT$: 'inexistent'
  [255]

  $ hg log -b '--config=ui.traceback=yes' 2>&1 | grep '^Traceback'
  Traceback (most recent call last):
  $ hg log -b '--config=profiling.enabled=yes' 2>&1 | grep -i sample
  Sample count: .*|No samples recorded\. (re)

Early options can't be specified in [aliases] and [defaults] because they are
applied before the command name is resolved:

  $ hg log -b '--config=alias.log=log --config=hooks.pre-log=false'
  hg log: option -b not recognized
  error in definition for alias 'log': --config may only be given on the command
  line
  [255]

  $ hg log -b '--config=defaults.log=--config=hooks.pre-log=false'
  abort: option --config may not be abbreviated!
  [255]

Shell aliases bypass any command parsing rules but for the early one:

  $ hg log -b '--config=alias.log=!echo howdy'
  howdy

Early options must come first if HGPLAIN=+strictflags is specified:
(BUG: chg cherry-picks early options to pass them as a server command)

#if no-chg
  $ HGPLAIN=+strictflags hg log -b --config='hooks.pre-log=false' default
  abort: unknown revision '--config=hooks.pre-log=false'!
  [255]
  $ HGPLAIN=+strictflags hg log -b -R. default
  abort: unknown revision '-R.'!
  [255]
  $ HGPLAIN=+strictflags hg log -b --cwd=. default
  abort: unknown revision '--cwd=.'!
  [255]
#endif
  $ HGPLAIN=+strictflags hg log -b --debugger default
  abort: unknown revision '--debugger'!
  [255]
  $ HGPLAIN=+strictflags hg log -b --config='alias.log=!echo pwned' default
  abort: unknown revision '--config=alias.log=!echo pwned'!
  [255]

  $ HGPLAIN=+strictflags hg log --config='hooks.pre-log=false' -b default
  abort: option --config may not be abbreviated!
  [255]
  $ HGPLAIN=+strictflags hg log -q --cwd=.. -b default
  abort: option --cwd may not be abbreviated!
  [255]
  $ HGPLAIN=+strictflags hg log -q -R . -b default
  abort: option -R has to be separated from other options (e.g. not -qR) and --repository may only be abbreviated as --repo!
  [255]

  $ HGPLAIN=+strictflags hg --config='hooks.pre-log=false' log -b default
  abort: pre-log hook exited with status 1
  [255]
  $ HGPLAIN=+strictflags hg --cwd .. -q -Ra log -b default
  0:cb9a9f314b8b
  $ HGPLAIN=+strictflags hg --cwd .. -q --repository a log -b default
  0:cb9a9f314b8b
  $ HGPLAIN=+strictflags hg --cwd .. -q --repo a log -b default
  0:cb9a9f314b8b

For compatibility reasons, HGPLAIN=+strictflags is not enabled by plain HGPLAIN:

  $ HGPLAIN= hg log --config='hooks.pre-log=false' -b default
  abort: pre-log hook exited with status 1
  [255]
  $ HGPLAINEXCEPT= hg log --cwd .. -q -Ra -b default
  0:cb9a9f314b8b

[defaults]

  $ hg cat a
  a
  $ cat >> $HGRCPATH <<EOF
  > [defaults]
  > cat = -r null
  > EOF
  $ hg cat a
  a: no such file in rev 000000000000
  [1]

  $ cd "$TESTTMP"

OSError "No such file or directory" / "The system cannot find the path
specified" should include filename even when it is empty

  $ hg -R a archive ''
  abort: *: '' (glob)
  [255]

#if no-outer-repo

No repo:

  $ hg cat
  abort: no repository found in '$TESTTMP' (.hg not found)!
  [255]

#endif

#if rmcwd

Current directory removed:

  $ mkdir $TESTTMP/repo1
  $ cd $TESTTMP/repo1
  $ rm -rf $TESTTMP/repo1

The output could be one of the following and something else:
 chg: abort: failed to getcwd (errno = *) (glob)
 abort: error getting current working directory: * (glob)
 sh: 0: getcwd() failed: $ENOENT$
Since the exact behavior depends on the shell, only check it returns non-zero.
  $ HGDEMANDIMPORT=disable hg version -q 2>/dev/null || false
  [1]

#endif