Mercurial > hg
view mercurial/wireprotoserver.py @ 36066:2ad145fbde54
wireprotoserver: add context manager mechanism for redirecting stdio
Today, proto.redirect() sets up redirecting stdio and proto.restore()
undoes that. The API is a bit wonky because restore() is only
implemented on the HTTP protocol. Furthermore, not all calls to
redirect() are obviously paired with calls to restore(). For
example, the call to restore() for "unbundle" requests is handled
by the response handler for the HTTP protocol.
This commit introduces a new method on the protocol handler interface
to maybe capture stdio. It emits a file object or None depending on
whether stdio capture is used by the transport.
To prove it works, the "pushkey" wire protocol command has been
updated to use the new API.
I'm not convinced this is the best mechanism to capture stdio. I may
need to come up with something better once the new wire protocol
emerges into existence. But it is strictly better than before because
it removes variance in the wire protocol handler interface. It
therefore gets us closer to a unified interface between the SSH and
HTTP transports.
Differential Revision: https://phab.mercurial-scm.org/D2081
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Wed, 07 Feb 2018 20:17:47 -0800 |
parents | bf676267f64f |
children | caca3ac2ac04 |
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# Copyright 21 May 2005 - (c) 2005 Jake Edge <jake@edge2.net> # Copyright 2005-2007 Matt Mackall <mpm@selenic.com> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from __future__ import absolute_import import abc import cgi import contextlib import struct import sys from .i18n import _ from . import ( encoding, error, hook, pycompat, util, wireproto, ) stringio = util.stringio urlerr = util.urlerr urlreq = util.urlreq HTTP_OK = 200 HGTYPE = 'application/mercurial-0.1' HGTYPE2 = 'application/mercurial-0.2' HGERRTYPE = 'application/hg-error' # Names of the SSH protocol implementations. SSHV1 = 'ssh-v1' # This is advertised over the wire. Incremental the counter at the end # to reflect BC breakages. SSHV2 = 'exp-ssh-v2-0001' class baseprotocolhandler(object): """Abstract base class for wire protocol handlers. A wire protocol handler serves as an interface between protocol command handlers and the wire protocol transport layer. Protocol handlers provide methods to read command arguments, redirect stdio for the duration of the request, handle response types, etc. """ __metaclass__ = abc.ABCMeta @abc.abstractproperty def name(self): """The name of the protocol implementation. Used for uniquely identifying the transport type. """ @abc.abstractmethod def getargs(self, args): """return the value for arguments in <args> returns a list of values (same order as <args>)""" @abc.abstractmethod def getfile(self, fp): """write the whole content of a file into a file like object The file is in the form:: (<chunk-size>\n<chunk>)+0\n chunk size is the ascii version of the int. """ @abc.abstractmethod def mayberedirectstdio(self): """Context manager to possibly redirect stdio. The context manager yields a file-object like object that receives stdout and stderr output when the context manager is active. Or it yields ``None`` if no I/O redirection occurs. The intent of this context manager is to capture stdio output so it may be sent in the response. Some transports support streaming stdio to the client in real time. For these transports, stdio output won't be captured. """ @abc.abstractmethod def redirect(self): """may setup interception for stdout and stderr See also the `restore` method.""" # If the `redirect` function does install interception, the `restore` # function MUST be defined. If interception is not used, this function # MUST NOT be defined. # # left commented here on purpose # #def restore(self): # """reinstall previous stdout and stderr and return intercepted stdout # """ # raise NotImplementedError() def decodevaluefromheaders(req, headerprefix): """Decode a long value from multiple HTTP request headers. Returns the value as a bytes, not a str. """ chunks = [] i = 1 prefix = headerprefix.upper().replace(r'-', r'_') while True: v = req.env.get(r'HTTP_%s_%d' % (prefix, i)) if v is None: break chunks.append(pycompat.bytesurl(v)) i += 1 return ''.join(chunks) class webproto(baseprotocolhandler): def __init__(self, req, ui): self._req = req self._ui = ui @property def name(self): return 'http' def getargs(self, args): knownargs = self._args() data = {} keys = args.split() for k in keys: if k == '*': star = {} for key in knownargs.keys(): if key != 'cmd' and key not in keys: star[key] = knownargs[key][0] data['*'] = star else: data[k] = knownargs[k][0] return [data[k] for k in keys] def _args(self): args = util.rapply(pycompat.bytesurl, self._req.form.copy()) postlen = int(self._req.env.get(r'HTTP_X_HGARGS_POST', 0)) if postlen: args.update(cgi.parse_qs( self._req.read(postlen), keep_blank_values=True)) return args argvalue = decodevaluefromheaders(self._req, r'X-HgArg') args.update(cgi.parse_qs(argvalue, keep_blank_values=True)) return args def getfile(self, fp): length = int(self._req.env[r'CONTENT_LENGTH']) # If httppostargs is used, we need to read Content-Length # minus the amount that was consumed by args. length -= int(self._req.env.get(r'HTTP_X_HGARGS_POST', 0)) for s in util.filechunkiter(self._req, limit=length): fp.write(s) @contextlib.contextmanager def mayberedirectstdio(self): oldout = self._ui.fout olderr = self._ui.ferr out = util.stringio() try: self._ui.fout = out self._ui.ferr = out yield out finally: self._ui.fout = oldout self._ui.ferr = olderr def redirect(self): self._oldio = self._ui.fout, self._ui.ferr self._ui.ferr = self._ui.fout = stringio() def restore(self): val = self._ui.fout.getvalue() self._ui.ferr, self._ui.fout = self._oldio return val def _client(self): return 'remote:%s:%s:%s' % ( self._req.env.get('wsgi.url_scheme') or 'http', urlreq.quote(self._req.env.get('REMOTE_HOST', '')), urlreq.quote(self._req.env.get('REMOTE_USER', ''))) def responsetype(self, prefer_uncompressed): """Determine the appropriate response type and compression settings. Returns a tuple of (mediatype, compengine, engineopts). """ # Determine the response media type and compression engine based # on the request parameters. protocaps = decodevaluefromheaders(self._req, r'X-HgProto').split(' ') if '0.2' in protocaps: # All clients are expected to support uncompressed data. if prefer_uncompressed: return HGTYPE2, util._noopengine(), {} # Default as defined by wire protocol spec. compformats = ['zlib', 'none'] for cap in protocaps: if cap.startswith('comp='): compformats = cap[5:].split(',') break # Now find an agreed upon compression format. for engine in wireproto.supportedcompengines(self._ui, self, util.SERVERROLE): if engine.wireprotosupport().name in compformats: opts = {} level = self._ui.configint('server', '%slevel' % engine.name()) if level is not None: opts['level'] = level return HGTYPE2, engine, opts # No mutually supported compression format. Fall back to the # legacy protocol. # Don't allow untrusted settings because disabling compression or # setting a very high compression level could lead to flooding # the server's network or CPU. opts = {'level': self._ui.configint('server', 'zliblevel')} return HGTYPE, util.compengines['zlib'], opts def iscmd(cmd): return cmd in wireproto.commands def parsehttprequest(repo, req, query): """Parse the HTTP request for a wire protocol request. If the current request appears to be a wire protocol request, this function returns a dict with details about that request, including an ``abstractprotocolserver`` instance suitable for handling the request. Otherwise, ``None`` is returned. ``req`` is a ``wsgirequest`` instance. """ # HTTP version 1 wire protocol requests are denoted by a "cmd" query # string parameter. If it isn't present, this isn't a wire protocol # request. if r'cmd' not in req.form: return None cmd = pycompat.sysbytes(req.form[r'cmd'][0]) # The "cmd" request parameter is used by both the wire protocol and hgweb. # While not all wire protocol commands are available for all transports, # if we see a "cmd" value that resembles a known wire protocol command, we # route it to a protocol handler. This is better than routing possible # wire protocol requests to hgweb because it prevents hgweb from using # known wire protocol commands and it is less confusing for machine # clients. if cmd not in wireproto.commands: return None proto = webproto(req, repo.ui) return { 'cmd': cmd, 'proto': proto, 'dispatch': lambda: _callhttp(repo, req, proto, cmd), 'handleerror': lambda ex: _handlehttperror(ex, req, cmd), } def _callhttp(repo, req, proto, cmd): def genversion2(gen, engine, engineopts): # application/mercurial-0.2 always sends a payload header # identifying the compression engine. name = engine.wireprotosupport().name assert 0 < len(name) < 256 yield struct.pack('B', len(name)) yield name for chunk in gen: yield chunk rsp = wireproto.dispatch(repo, proto, cmd) if not wireproto.commands.commandavailable(cmd, proto): req.respond(HTTP_OK, HGERRTYPE, body=_('requested wire protocol command is not available ' 'over HTTP')) return [] if isinstance(rsp, bytes): req.respond(HTTP_OK, HGTYPE, body=rsp) return [] elif isinstance(rsp, wireproto.streamres_legacy): gen = rsp.gen req.respond(HTTP_OK, HGTYPE) return gen elif isinstance(rsp, wireproto.streamres): gen = rsp.gen # This code for compression should not be streamres specific. It # is here because we only compress streamres at the moment. mediatype, engine, engineopts = proto.responsetype( rsp.prefer_uncompressed) gen = engine.compressstream(gen, engineopts) if mediatype == HGTYPE2: gen = genversion2(gen, engine, engineopts) req.respond(HTTP_OK, mediatype) return gen elif isinstance(rsp, wireproto.pushres): val = proto.restore() rsp = '%d\n%s' % (rsp.res, val) req.respond(HTTP_OK, HGTYPE, body=rsp) return [] elif isinstance(rsp, wireproto.pusherr): # This is the httplib workaround documented in _handlehttperror(). req.drain() proto.restore() rsp = '0\n%s\n' % rsp.res req.respond(HTTP_OK, HGTYPE, body=rsp) return [] elif isinstance(rsp, wireproto.ooberror): rsp = rsp.message req.respond(HTTP_OK, HGERRTYPE, body=rsp) return [] raise error.ProgrammingError('hgweb.protocol internal failure', rsp) def _handlehttperror(e, req, cmd): """Called when an ErrorResponse is raised during HTTP request processing.""" # Clients using Python's httplib are stateful: the HTTP client # won't process an HTTP response until all request data is # sent to the server. The intent of this code is to ensure # we always read HTTP request data from the client, thus # ensuring httplib transitions to a state that allows it to read # the HTTP response. In other words, it helps prevent deadlocks # on clients using httplib. if (req.env[r'REQUEST_METHOD'] == r'POST' and # But not if Expect: 100-continue is being used. (req.env.get('HTTP_EXPECT', '').lower() != '100-continue') or # Or the non-httplib HTTP library is being advertised by # the client. req.env.get('X-HgHttp2', '')): req.drain() else: req.headers.append((r'Connection', r'Close')) # TODO This response body assumes the failed command was # "unbundle." That assumption is not always valid. req.respond(e, HGTYPE, body='0\n%s\n' % e) return '' def _sshv1respondbytes(fout, value): """Send a bytes response for protocol version 1.""" fout.write('%d\n' % len(value)) fout.write(value) fout.flush() def _sshv1respondstream(fout, source): write = fout.write for chunk in source.gen: write(chunk) fout.flush() def _sshv1respondooberror(fout, ferr, rsp): ferr.write(b'%s\n-\n' % rsp) ferr.flush() fout.write(b'\n') fout.flush() class sshv1protocolhandler(baseprotocolhandler): """Handler for requests services via version 1 of SSH protocol.""" def __init__(self, ui, fin, fout): self._ui = ui self._fin = fin self._fout = fout @property def name(self): return 'ssh' def getargs(self, args): data = {} keys = args.split() for n in xrange(len(keys)): argline = self._fin.readline()[:-1] arg, l = argline.split() if arg not in keys: raise error.Abort(_("unexpected parameter %r") % arg) if arg == '*': star = {} for k in xrange(int(l)): argline = self._fin.readline()[:-1] arg, l = argline.split() val = self._fin.read(int(l)) star[arg] = val data['*'] = star else: val = self._fin.read(int(l)) data[arg] = val return [data[k] for k in keys] def getfile(self, fpout): _sshv1respondbytes(self._fout, b'') count = int(self._fin.readline()) while count: fpout.write(self._fin.read(count)) count = int(self._fin.readline()) @contextlib.contextmanager def mayberedirectstdio(self): yield None def redirect(self): pass def _client(self): client = encoding.environ.get('SSH_CLIENT', '').split(' ', 1)[0] return 'remote:ssh:' + client class sshserver(object): def __init__(self, ui, repo): self._ui = ui self._repo = repo self._fin = ui.fin self._fout = ui.fout hook.redirect(True) ui.fout = repo.ui.fout = ui.ferr # Prevent insertion/deletion of CRs util.setbinary(self._fin) util.setbinary(self._fout) self._proto = sshv1protocolhandler(self._ui, self._fin, self._fout) def serve_forever(self): while self.serve_one(): pass sys.exit(0) def serve_one(self): cmd = self._fin.readline()[:-1] if cmd and wireproto.commands.commandavailable(cmd, self._proto): rsp = wireproto.dispatch(self._repo, self._proto, cmd) if isinstance(rsp, bytes): _sshv1respondbytes(self._fout, rsp) elif isinstance(rsp, wireproto.streamres): _sshv1respondstream(self._fout, rsp) elif isinstance(rsp, wireproto.streamres_legacy): _sshv1respondstream(self._fout, rsp) elif isinstance(rsp, wireproto.pushres): _sshv1respondbytes(self._fout, b'') _sshv1respondbytes(self._fout, bytes(rsp.res)) elif isinstance(rsp, wireproto.pusherr): _sshv1respondbytes(self._fout, rsp.res) elif isinstance(rsp, wireproto.ooberror): _sshv1respondooberror(self._fout, self._ui.ferr, rsp.message) else: raise error.ProgrammingError('unhandled response type from ' 'wire protocol command: %s' % rsp) elif cmd: _sshv1respondbytes(self._fout, b'') return cmd != ''