| lothiraldan | |
| yuja |
| hg-reviewers |
The mechanism by which SSH peers establish connections with remotes
is wonky and requires a bit of code archeology to understand. While
it is already documented in hg help internals.wireproto, it helps
to have documentation in the code as well.
| Lint Skipped |
| Unit Tests Skipped |
| return proc, stdin, stdout, stderr | return proc, stdin, stdout, stderr | ||||
| def _performhandshake(ui, stdin, stdout, stderr): | def _performhandshake(ui, stdin, stdout, stderr): | ||||
| def badresponse(): | def badresponse(): | ||||
| msg = _('no suitable response from remote hg') | msg = _('no suitable response from remote hg') | ||||
| hint = ui.config('ui', 'ssherrorhint') | hint = ui.config('ui', 'ssherrorhint') | ||||
| raise error.RepoError(msg, hint=hint) | raise error.RepoError(msg, hint=hint) | ||||
| # The handshake consists of sending 2 wire protocol commands: | |||||
| # ``hello`` and ``between``. | |||||
| # | |||||
| # The ``hello`` command (which was introduced in Mercurial 0.9.1) | |||||
| # instructs the server to advertise its capabilities. | |||||
| # | |||||
| # The ``between`` command (which has existed in all Mercurial servers | |||||
| # for as long as SSH support has existed), asks for the set of revisions | |||||
| # between a pair of revisions. | |||||
| # | |||||
| # The ``between`` command is issued with a request for the null | |||||
| # range. If the remote is a Mercurial server, this request will | |||||
| # generate a specific response: ``1\n\n``. This represents the | |||||
| # wire protocol encoded value for ``\n``. We look for ``1\n\n`` | |||||
| # in the output stream and know this is the response to ``between`` | |||||
| # and we're at the end of our handshake reply. | |||||
| # | |||||
| # The response to the ``hello`` command will be a line with the | |||||
| # length of the value returned by that command followed by that | |||||
| # value. If the server doesn't support ``hello`` (which should be | |||||
| # rare), that line will be ``0\n``. Otherwise, the value will contain | |||||
| # RFC 822 like lines. Of these, the ``capabilities:`` line contains | |||||
| # the capabilities of the server. | |||||
| # | |||||
| # In addition to the responses to our command requests, the server | |||||
| # may emit "banner" output on stdout. SSH servers are allowed to | |||||
| # print messages to stdout on login. Issuing commands on connection | |||||
| # allows us to flush this banner output from the server by scanning | |||||
| # for output to our well-known ``between`` command. Of course, if | |||||
| # the banner contains ``1\n\n``, this will throw off our detection. | |||||
| requestlog = ui.configbool('devel', 'debug.peer-request') | requestlog = ui.configbool('devel', 'debug.peer-request') | ||||
| try: | try: | ||||
| pairsarg = '%s-%s' % ('0' * 40, '0' * 40) | pairsarg = '%s-%s' % ('0' * 40, '0' * 40) | ||||
| handshake = [ | handshake = [ | ||||
| 'hello\n', | 'hello\n', | ||||
| 'between\n', | 'between\n', | ||||
| 'pairs %d\n' % len(pairsarg), | 'pairs %d\n' % len(pairsarg), | ||||
| max_noise -= 1 | max_noise -= 1 | ||||
| except IOError: | except IOError: | ||||
| badresponse() | badresponse() | ||||
| else: | else: | ||||
| badresponse() | badresponse() | ||||
| caps = set() | caps = set() | ||||
| for l in reversed(lines): | for l in reversed(lines): | ||||
| # Look for response to ``hello`` command. Scan from the back so | |||||
| # we don't misinterpret banner output as the command reply. | |||||
| if l.startswith('capabilities:'): | if l.startswith('capabilities:'): | ||||
| caps.update(l[:-1].split(':')[1].split()) | caps.update(l[:-1].split(':')[1].split()) | ||||
| break | break | ||||
| return caps | return caps | ||||
| class sshpeer(wireproto.wirepeer): | class sshpeer(wireproto.wirepeer): | ||||
| def __init__(self, ui, url, proc, stdin, stdout, stderr, caps): | def __init__(self, ui, url, proc, stdin, stdout, stderr, caps): | ||||