| 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 |
| self._pipei = doublepipe(self.ui, self._pipei, self._pipee) | self._pipei = doublepipe(self.ui, self._pipei, self._pipee) | ||||
| self._pipeo = doublepipe(self.ui, self._pipeo, self._pipee) | self._pipeo = doublepipe(self.ui, self._pipeo, self._pipee) | ||||
| def badresponse(): | def badresponse(): | ||||
| msg = _("no suitable response from remote hg") | msg = _("no suitable response from remote hg") | ||||
| hint = self.ui.config("ui", "ssherrorhint") | hint = self.ui.config("ui", "ssherrorhint") | ||||
| self._abort(error.RepoError(msg, hint=hint)) | self._abort(error.RepoError(msg, hint=hint)) | ||||
| # The purpose of the ``between`` command with a null range is to | |||||
| # reliably get a specific response (``1\n\n`` - a 1 byte reply | |||||
| # with value ``\n``) from *all* servers, possibly after "noise" | |||||
| # emitted by the server (e.g. message of the day banners). The | |||||
| # ``between`` command has existed for as long as the SSH peer has | |||||
| # existed, which is how we know that we can rely on that command | |||||
| # working. If we send the ``between`` command, we should see | |||||
| # ``1\n\n`` in the response. If not, the remote isn't a valid | |||||
| # Mercurial server. | |||||
| # | |||||
| # The ``hello`` command was added in Mercurial 0.9.1 as a mechanism for | |||||
| # servers to advertise their capabilities. The client sends both | |||||
| # ``hello`` and ``between`` to tease out old servers. If the server | |||||
| # doesn't support ``hello``, it will send an empty reply (``0\n``) to | |||||
| # that command. However, there will always be a reply to the ``between`` | |||||
| # command allowing us to differentiate between "noise" and command | |||||
| # response. | |||||
| try: | try: | ||||
| # skip any noise generated by remote shell | |||||
| self._callstream("hello") | self._callstream("hello") | ||||
| r = self._callstream("between", pairs=("%s-%s" % ("0"*40, "0"*40))) | r = self._callstream("between", pairs=("%s-%s" % ("0"*40, "0"*40))) | ||||
| except IOError: | except IOError: | ||||
| badresponse() | badresponse() | ||||
| lines = ["", "dummy"] | lines = ["", "dummy"] | ||||
| max_noise = 500 | max_noise = 500 | ||||
| while lines[-1] and max_noise: | while lines[-1] and max_noise: | ||||
| try: | try: | ||||
| l = r.readline() | l = r.readline() | ||||
| self._readerr() | self._readerr() | ||||
| if lines[-1] == "1\n" and l == "\n": | if lines[-1] == "1\n" and l == "\n": | ||||
| break | break | ||||
| if l: | if l: | ||||
| self.ui.debug("remote: ", l) | self.ui.debug("remote: ", l) | ||||
| lines.append(l) | lines.append(l) | ||||
| max_noise -= 1 | max_noise -= 1 | ||||
| except IOError: | except IOError: | ||||
| badresponse() | badresponse() | ||||
| else: | else: | ||||
| badresponse() | badresponse() | ||||
| # Search for the ``hello`` response in reverse wire order. If there | |||||
| # was e.g. an SSH banner that happened to emit ``capabilities:``, that | |||||
| # should be before Mercurial's output. | |||||
| self._caps = set() | self._caps = set() | ||||
| for l in reversed(lines): | for l in reversed(lines): | ||||
| if l.startswith("capabilities:"): | if l.startswith("capabilities:"): | ||||
| self._caps.update(l[:-1].split(":")[1].split()) | self._caps.update(l[:-1].split(":")[1].split()) | ||||
| break | break | ||||
| def _readerr(self): | def _readerr(self): | ||||
| _forwardoutput(self.ui, self._pipee) | _forwardoutput(self.ui, self._pipee) | ||||