Mercurial > hg
view mercurial/wireprotoframing.py @ 40767:33d30fb1e4ae
push: config option to control behavior when pushing to a publishing server
Pushing to a publishing server by mistake can lead to a difficult situation to
solve because evolution doesn't work on public changesets. This new
experimental config tries to help avoiding unintentionally (or at least being
aware of) pushing to publishing remotes.
`hg push --publish` can be used to make push succeed even when auto-publish is
set to 'abort'.
author | Anton Shestakov <av6@dwimlabs.net> |
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date | Mon, 05 Nov 2018 13:52:19 +0800 |
parents | 2c55716f8a1c |
children | 2372284d9457 |
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line source
# wireprotoframing.py - unified framing protocol for wire protocol # # Copyright 2018 Gregory Szorc <gregory.szorc@gmail.com> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. # This file contains functionality to support the unified frame-based wire # protocol. For details about the protocol, see # `hg help internals.wireprotocol`. from __future__ import absolute_import import collections import struct from .i18n import _ from .thirdparty import ( attr, ) from . import ( encoding, error, pycompat, util, wireprototypes, ) from .utils import ( cborutil, stringutil, ) FRAME_HEADER_SIZE = 8 DEFAULT_MAX_FRAME_SIZE = 32768 STREAM_FLAG_BEGIN_STREAM = 0x01 STREAM_FLAG_END_STREAM = 0x02 STREAM_FLAG_ENCODING_APPLIED = 0x04 STREAM_FLAGS = { b'stream-begin': STREAM_FLAG_BEGIN_STREAM, b'stream-end': STREAM_FLAG_END_STREAM, b'encoded': STREAM_FLAG_ENCODING_APPLIED, } FRAME_TYPE_COMMAND_REQUEST = 0x01 FRAME_TYPE_COMMAND_DATA = 0x02 FRAME_TYPE_COMMAND_RESPONSE = 0x03 FRAME_TYPE_ERROR_RESPONSE = 0x05 FRAME_TYPE_TEXT_OUTPUT = 0x06 FRAME_TYPE_PROGRESS = 0x07 FRAME_TYPE_SENDER_PROTOCOL_SETTINGS = 0x08 FRAME_TYPE_STREAM_SETTINGS = 0x09 FRAME_TYPES = { b'command-request': FRAME_TYPE_COMMAND_REQUEST, b'command-data': FRAME_TYPE_COMMAND_DATA, b'command-response': FRAME_TYPE_COMMAND_RESPONSE, b'error-response': FRAME_TYPE_ERROR_RESPONSE, b'text-output': FRAME_TYPE_TEXT_OUTPUT, b'progress': FRAME_TYPE_PROGRESS, b'sender-protocol-settings': FRAME_TYPE_SENDER_PROTOCOL_SETTINGS, b'stream-settings': FRAME_TYPE_STREAM_SETTINGS, } FLAG_COMMAND_REQUEST_NEW = 0x01 FLAG_COMMAND_REQUEST_CONTINUATION = 0x02 FLAG_COMMAND_REQUEST_MORE_FRAMES = 0x04 FLAG_COMMAND_REQUEST_EXPECT_DATA = 0x08 FLAGS_COMMAND_REQUEST = { b'new': FLAG_COMMAND_REQUEST_NEW, b'continuation': FLAG_COMMAND_REQUEST_CONTINUATION, b'more': FLAG_COMMAND_REQUEST_MORE_FRAMES, b'have-data': FLAG_COMMAND_REQUEST_EXPECT_DATA, } FLAG_COMMAND_DATA_CONTINUATION = 0x01 FLAG_COMMAND_DATA_EOS = 0x02 FLAGS_COMMAND_DATA = { b'continuation': FLAG_COMMAND_DATA_CONTINUATION, b'eos': FLAG_COMMAND_DATA_EOS, } FLAG_COMMAND_RESPONSE_CONTINUATION = 0x01 FLAG_COMMAND_RESPONSE_EOS = 0x02 FLAGS_COMMAND_RESPONSE = { b'continuation': FLAG_COMMAND_RESPONSE_CONTINUATION, b'eos': FLAG_COMMAND_RESPONSE_EOS, } FLAG_SENDER_PROTOCOL_SETTINGS_CONTINUATION = 0x01 FLAG_SENDER_PROTOCOL_SETTINGS_EOS = 0x02 FLAGS_SENDER_PROTOCOL_SETTINGS = { b'continuation': FLAG_SENDER_PROTOCOL_SETTINGS_CONTINUATION, b'eos': FLAG_SENDER_PROTOCOL_SETTINGS_EOS, } FLAG_STREAM_ENCODING_SETTINGS_CONTINUATION = 0x01 FLAG_STREAM_ENCODING_SETTINGS_EOS = 0x02 FLAGS_STREAM_ENCODING_SETTINGS = { b'continuation': FLAG_STREAM_ENCODING_SETTINGS_CONTINUATION, b'eos': FLAG_STREAM_ENCODING_SETTINGS_EOS, } # Maps frame types to their available flags. FRAME_TYPE_FLAGS = { FRAME_TYPE_COMMAND_REQUEST: FLAGS_COMMAND_REQUEST, FRAME_TYPE_COMMAND_DATA: FLAGS_COMMAND_DATA, FRAME_TYPE_COMMAND_RESPONSE: FLAGS_COMMAND_RESPONSE, FRAME_TYPE_ERROR_RESPONSE: {}, FRAME_TYPE_TEXT_OUTPUT: {}, FRAME_TYPE_PROGRESS: {}, FRAME_TYPE_SENDER_PROTOCOL_SETTINGS: FLAGS_SENDER_PROTOCOL_SETTINGS, FRAME_TYPE_STREAM_SETTINGS: FLAGS_STREAM_ENCODING_SETTINGS, } ARGUMENT_RECORD_HEADER = struct.Struct(r'<HH') def humanflags(mapping, value): """Convert a numeric flags value to a human value, using a mapping table.""" namemap = {v: k for k, v in mapping.iteritems()} flags = [] val = 1 while value >= val: if value & val: flags.append(namemap.get(val, '<unknown 0x%02x>' % val)) val <<= 1 return b'|'.join(flags) @attr.s(slots=True) class frameheader(object): """Represents the data in a frame header.""" length = attr.ib() requestid = attr.ib() streamid = attr.ib() streamflags = attr.ib() typeid = attr.ib() flags = attr.ib() @attr.s(slots=True, repr=False) class frame(object): """Represents a parsed frame.""" requestid = attr.ib() streamid = attr.ib() streamflags = attr.ib() typeid = attr.ib() flags = attr.ib() payload = attr.ib() @encoding.strmethod def __repr__(self): typename = '<unknown 0x%02x>' % self.typeid for name, value in FRAME_TYPES.iteritems(): if value == self.typeid: typename = name break return ('frame(size=%d; request=%d; stream=%d; streamflags=%s; ' 'type=%s; flags=%s)' % ( len(self.payload), self.requestid, self.streamid, humanflags(STREAM_FLAGS, self.streamflags), typename, humanflags(FRAME_TYPE_FLAGS.get(self.typeid, {}), self.flags))) def makeframe(requestid, streamid, streamflags, typeid, flags, payload): """Assemble a frame into a byte array.""" # TODO assert size of payload. frame = bytearray(FRAME_HEADER_SIZE + len(payload)) # 24 bits length # 16 bits request id # 8 bits stream id # 8 bits stream flags # 4 bits type # 4 bits flags l = struct.pack(r'<I', len(payload)) frame[0:3] = l[0:3] struct.pack_into(r'<HBB', frame, 3, requestid, streamid, streamflags) frame[7] = (typeid << 4) | flags frame[8:] = payload return frame def makeframefromhumanstring(s): """Create a frame from a human readable string Strings have the form: <request-id> <stream-id> <stream-flags> <type> <flags> <payload> This can be used by user-facing applications and tests for creating frames easily without having to type out a bunch of constants. Request ID and stream IDs are integers. Stream flags, frame type, and flags can be specified by integer or named constant. Flags can be delimited by `|` to bitwise OR them together. If the payload begins with ``cbor:``, the following string will be evaluated as Python literal and the resulting object will be fed into a CBOR encoder. Otherwise, the payload is interpreted as a Python byte string literal. """ fields = s.split(b' ', 5) requestid, streamid, streamflags, frametype, frameflags, payload = fields requestid = int(requestid) streamid = int(streamid) finalstreamflags = 0 for flag in streamflags.split(b'|'): if flag in STREAM_FLAGS: finalstreamflags |= STREAM_FLAGS[flag] else: finalstreamflags |= int(flag) if frametype in FRAME_TYPES: frametype = FRAME_TYPES[frametype] else: frametype = int(frametype) finalflags = 0 validflags = FRAME_TYPE_FLAGS[frametype] for flag in frameflags.split(b'|'): if flag in validflags: finalflags |= validflags[flag] else: finalflags |= int(flag) if payload.startswith(b'cbor:'): payload = b''.join(cborutil.streamencode( stringutil.evalpythonliteral(payload[5:]))) else: payload = stringutil.unescapestr(payload) return makeframe(requestid=requestid, streamid=streamid, streamflags=finalstreamflags, typeid=frametype, flags=finalflags, payload=payload) def parseheader(data): """Parse a unified framing protocol frame header from a buffer. The header is expected to be in the buffer at offset 0 and the buffer is expected to be large enough to hold a full header. """ # 24 bits payload length (little endian) # 16 bits request ID # 8 bits stream ID # 8 bits stream flags # 4 bits frame type # 4 bits frame flags # ... payload framelength = data[0] + 256 * data[1] + 16384 * data[2] requestid, streamid, streamflags = struct.unpack_from(r'<HBB', data, 3) typeflags = data[7] frametype = (typeflags & 0xf0) >> 4 frameflags = typeflags & 0x0f return frameheader(framelength, requestid, streamid, streamflags, frametype, frameflags) def readframe(fh): """Read a unified framing protocol frame from a file object. Returns a 3-tuple of (type, flags, payload) for the decoded frame or None if no frame is available. May raise if a malformed frame is seen. """ header = bytearray(FRAME_HEADER_SIZE) readcount = fh.readinto(header) if readcount == 0: return None if readcount != FRAME_HEADER_SIZE: raise error.Abort(_('received incomplete frame: got %d bytes: %s') % (readcount, header)) h = parseheader(header) payload = fh.read(h.length) if len(payload) != h.length: raise error.Abort(_('frame length error: expected %d; got %d') % (h.length, len(payload))) return frame(h.requestid, h.streamid, h.streamflags, h.typeid, h.flags, payload) def createcommandframes(stream, requestid, cmd, args, datafh=None, maxframesize=DEFAULT_MAX_FRAME_SIZE, redirect=None): """Create frames necessary to transmit a request to run a command. This is a generator of bytearrays. Each item represents a frame ready to be sent over the wire to a peer. """ data = {b'name': cmd} if args: data[b'args'] = args if redirect: data[b'redirect'] = redirect data = b''.join(cborutil.streamencode(data)) offset = 0 while True: flags = 0 # Must set new or continuation flag. if not offset: flags |= FLAG_COMMAND_REQUEST_NEW else: flags |= FLAG_COMMAND_REQUEST_CONTINUATION # Data frames is set on all frames. if datafh: flags |= FLAG_COMMAND_REQUEST_EXPECT_DATA payload = data[offset:offset + maxframesize] offset += len(payload) if len(payload) == maxframesize and offset < len(data): flags |= FLAG_COMMAND_REQUEST_MORE_FRAMES yield stream.makeframe(requestid=requestid, typeid=FRAME_TYPE_COMMAND_REQUEST, flags=flags, payload=payload) if not (flags & FLAG_COMMAND_REQUEST_MORE_FRAMES): break if datafh: while True: data = datafh.read(DEFAULT_MAX_FRAME_SIZE) done = False if len(data) == DEFAULT_MAX_FRAME_SIZE: flags = FLAG_COMMAND_DATA_CONTINUATION else: flags = FLAG_COMMAND_DATA_EOS assert datafh.read(1) == b'' done = True yield stream.makeframe(requestid=requestid, typeid=FRAME_TYPE_COMMAND_DATA, flags=flags, payload=data) if done: break def createcommandresponseokframe(stream, requestid): overall = b''.join(cborutil.streamencode({b'status': b'ok'})) if stream.streamsettingssent: overall = stream.encode(overall) encoded = True if not overall: return None else: encoded = False return stream.makeframe(requestid=requestid, typeid=FRAME_TYPE_COMMAND_RESPONSE, flags=FLAG_COMMAND_RESPONSE_CONTINUATION, payload=overall, encoded=encoded) def createcommandresponseeosframes(stream, requestid, maxframesize=DEFAULT_MAX_FRAME_SIZE): """Create an empty payload frame representing command end-of-stream.""" payload = stream.flush() offset = 0 while True: chunk = payload[offset:offset + maxframesize] offset += len(chunk) done = offset == len(payload) if done: flags = FLAG_COMMAND_RESPONSE_EOS else: flags = FLAG_COMMAND_RESPONSE_CONTINUATION yield stream.makeframe(requestid=requestid, typeid=FRAME_TYPE_COMMAND_RESPONSE, flags=flags, payload=chunk, encoded=payload != b'') if done: break def createalternatelocationresponseframe(stream, requestid, location): data = { b'status': b'redirect', b'location': { b'url': location.url, b'mediatype': location.mediatype, } } for a in (r'size', r'fullhashes', r'fullhashseed', r'serverdercerts', r'servercadercerts'): value = getattr(location, a) if value is not None: data[b'location'][pycompat.bytestr(a)] = value payload = b''.join(cborutil.streamencode(data)) if stream.streamsettingssent: payload = stream.encode(payload) encoded = True else: encoded = False return stream.makeframe(requestid=requestid, typeid=FRAME_TYPE_COMMAND_RESPONSE, flags=FLAG_COMMAND_RESPONSE_CONTINUATION, payload=payload, encoded=encoded) def createcommanderrorresponse(stream, requestid, message, args=None): # TODO should this be using a list of {'msg': ..., 'args': {}} so atom # formatting works consistently? m = { b'status': b'error', b'error': { b'message': message, } } if args: m[b'error'][b'args'] = args overall = b''.join(cborutil.streamencode(m)) yield stream.makeframe(requestid=requestid, typeid=FRAME_TYPE_COMMAND_RESPONSE, flags=FLAG_COMMAND_RESPONSE_EOS, payload=overall) def createerrorframe(stream, requestid, msg, errtype): # TODO properly handle frame size limits. assert len(msg) <= DEFAULT_MAX_FRAME_SIZE payload = b''.join(cborutil.streamencode({ b'type': errtype, b'message': [{b'msg': msg}], })) yield stream.makeframe(requestid=requestid, typeid=FRAME_TYPE_ERROR_RESPONSE, flags=0, payload=payload) def createtextoutputframe(stream, requestid, atoms, maxframesize=DEFAULT_MAX_FRAME_SIZE): """Create a text output frame to render text to people. ``atoms`` is a 3-tuple of (formatting string, args, labels). The formatting string contains ``%s`` tokens to be replaced by the corresponding indexed entry in ``args``. ``labels`` is an iterable of formatters to be applied at rendering time. In terms of the ``ui`` class, each atom corresponds to a ``ui.write()``. """ atomdicts = [] for (formatting, args, labels) in atoms: # TODO look for localstr, other types here? if not isinstance(formatting, bytes): raise ValueError('must use bytes formatting strings') for arg in args: if not isinstance(arg, bytes): raise ValueError('must use bytes for arguments') for label in labels: if not isinstance(label, bytes): raise ValueError('must use bytes for labels') # Formatting string must be ASCII. formatting = formatting.decode(r'ascii', r'replace').encode(r'ascii') # Arguments must be UTF-8. args = [a.decode(r'utf-8', r'replace').encode(r'utf-8') for a in args] # Labels must be ASCII. labels = [l.decode(r'ascii', r'strict').encode(r'ascii') for l in labels] atom = {b'msg': formatting} if args: atom[b'args'] = args if labels: atom[b'labels'] = labels atomdicts.append(atom) payload = b''.join(cborutil.streamencode(atomdicts)) if len(payload) > maxframesize: raise ValueError('cannot encode data in a single frame') yield stream.makeframe(requestid=requestid, typeid=FRAME_TYPE_TEXT_OUTPUT, flags=0, payload=payload) class bufferingcommandresponseemitter(object): """Helper object to emit command response frames intelligently. Raw command response data is likely emitted in chunks much smaller than what can fit in a single frame. This class exists to buffer chunks until enough data is available to fit in a single frame. TODO we'll need something like this when compression is supported. So it might make sense to implement this functionality at the stream level. """ def __init__(self, stream, requestid, maxframesize=DEFAULT_MAX_FRAME_SIZE): self._stream = stream self._requestid = requestid self._maxsize = maxframesize self._chunks = [] self._chunkssize = 0 def send(self, data): """Send new data for emission. Is a generator of new frames that were derived from the new input. If the special input ``None`` is received, flushes all buffered data to frames. """ if data is None: for frame in self._flush(): yield frame return data = self._stream.encode(data) # There is a ton of potential to do more complicated things here. # Our immediate goal is to coalesce small chunks into big frames, # not achieve the fewest number of frames possible. So we go with # a simple implementation: # # * If a chunk is too large for a frame, we flush and emit frames # for the new chunk. # * If a chunk can be buffered without total buffered size limits # being exceeded, we do that. # * If a chunk causes us to go over our buffering limit, we flush # and then buffer the new chunk. if not data: return if len(data) > self._maxsize: for frame in self._flush(): yield frame # Now emit frames for the big chunk. offset = 0 while True: chunk = data[offset:offset + self._maxsize] offset += len(chunk) yield self._stream.makeframe( self._requestid, typeid=FRAME_TYPE_COMMAND_RESPONSE, flags=FLAG_COMMAND_RESPONSE_CONTINUATION, payload=chunk, encoded=True) if offset == len(data): return # If we don't have enough to constitute a full frame, buffer and # return. if len(data) + self._chunkssize < self._maxsize: self._chunks.append(data) self._chunkssize += len(data) return # Else flush what we have and buffer the new chunk. We could do # something more intelligent here, like break the chunk. Let's # keep things simple for now. for frame in self._flush(): yield frame self._chunks.append(data) self._chunkssize = len(data) def _flush(self): payload = b''.join(self._chunks) assert len(payload) <= self._maxsize self._chunks[:] = [] self._chunkssize = 0 if not payload: return yield self._stream.makeframe( self._requestid, typeid=FRAME_TYPE_COMMAND_RESPONSE, flags=FLAG_COMMAND_RESPONSE_CONTINUATION, payload=payload, encoded=True) # TODO consider defining encoders/decoders using the util.compressionengine # mechanism. class identityencoder(object): """Encoder for the "identity" stream encoding profile.""" def __init__(self, ui): pass def encode(self, data): return data def flush(self): return b'' def finish(self): return b'' class identitydecoder(object): """Decoder for the "identity" stream encoding profile.""" def __init__(self, ui, extraobjs): if extraobjs: raise error.Abort(_('identity decoder received unexpected ' 'additional values')) def decode(self, data): return data class zlibencoder(object): def __init__(self, ui): import zlib self._zlib = zlib self._compressor = zlib.compressobj() def encode(self, data): return self._compressor.compress(data) def flush(self): # Z_SYNC_FLUSH doesn't reset compression context, which is # what we want. return self._compressor.flush(self._zlib.Z_SYNC_FLUSH) def finish(self): res = self._compressor.flush(self._zlib.Z_FINISH) self._compressor = None return res class zlibdecoder(object): def __init__(self, ui, extraobjs): import zlib if extraobjs: raise error.Abort(_('zlib decoder received unexpected ' 'additional values')) self._decompressor = zlib.decompressobj() def decode(self, data): # Python 2's zlib module doesn't use the buffer protocol and can't # handle all bytes-like types. if not pycompat.ispy3 and isinstance(data, bytearray): data = bytes(data) return self._decompressor.decompress(data) class zstdbaseencoder(object): def __init__(self, level): from . import zstd self._zstd = zstd cctx = zstd.ZstdCompressor(level=level) self._compressor = cctx.compressobj() def encode(self, data): return self._compressor.compress(data) def flush(self): # COMPRESSOBJ_FLUSH_BLOCK flushes all data previously fed into the # compressor and allows a decompressor to access all encoded data # up to this point. return self._compressor.flush(self._zstd.COMPRESSOBJ_FLUSH_BLOCK) def finish(self): res = self._compressor.flush(self._zstd.COMPRESSOBJ_FLUSH_FINISH) self._compressor = None return res class zstd8mbencoder(zstdbaseencoder): def __init__(self, ui): super(zstd8mbencoder, self).__init__(3) class zstdbasedecoder(object): def __init__(self, maxwindowsize): from . import zstd dctx = zstd.ZstdDecompressor(max_window_size=maxwindowsize) self._decompressor = dctx.decompressobj() def decode(self, data): return self._decompressor.decompress(data) class zstd8mbdecoder(zstdbasedecoder): def __init__(self, ui, extraobjs): if extraobjs: raise error.Abort(_('zstd8mb decoder received unexpected ' 'additional values')) super(zstd8mbdecoder, self).__init__(maxwindowsize=8 * 1048576) # We lazily populate this to avoid excessive module imports when importing # this module. STREAM_ENCODERS = {} STREAM_ENCODERS_ORDER = [] def populatestreamencoders(): if STREAM_ENCODERS: return try: from . import zstd zstd.__version__ except ImportError: zstd = None # zstandard is fastest and is preferred. if zstd: STREAM_ENCODERS[b'zstd-8mb'] = (zstd8mbencoder, zstd8mbdecoder) STREAM_ENCODERS_ORDER.append(b'zstd-8mb') STREAM_ENCODERS[b'zlib'] = (zlibencoder, zlibdecoder) STREAM_ENCODERS_ORDER.append(b'zlib') STREAM_ENCODERS[b'identity'] = (identityencoder, identitydecoder) STREAM_ENCODERS_ORDER.append(b'identity') class stream(object): """Represents a logical unidirectional series of frames.""" def __init__(self, streamid, active=False): self.streamid = streamid self._active = active def makeframe(self, requestid, typeid, flags, payload): """Create a frame to be sent out over this stream. Only returns the frame instance. Does not actually send it. """ streamflags = 0 if not self._active: streamflags |= STREAM_FLAG_BEGIN_STREAM self._active = True return makeframe(requestid, self.streamid, streamflags, typeid, flags, payload) class inputstream(stream): """Represents a stream used for receiving data.""" def __init__(self, streamid, active=False): super(inputstream, self).__init__(streamid, active=active) self._decoder = None def setdecoder(self, ui, name, extraobjs): """Set the decoder for this stream. Receives the stream profile name and any additional CBOR objects decoded from the stream encoding settings frame payloads. """ if name not in STREAM_ENCODERS: raise error.Abort(_('unknown stream decoder: %s') % name) self._decoder = STREAM_ENCODERS[name][1](ui, extraobjs) def decode(self, data): # Default is identity decoder. We don't bother instantiating one # because it is trivial. if not self._decoder: return data return self._decoder.decode(data) def flush(self): if not self._decoder: return b'' return self._decoder.flush() class outputstream(stream): """Represents a stream used for sending data.""" def __init__(self, streamid, active=False): super(outputstream, self).__init__(streamid, active=active) self.streamsettingssent = False self._encoder = None self._encodername = None def setencoder(self, ui, name): """Set the encoder for this stream. Receives the stream profile name. """ if name not in STREAM_ENCODERS: raise error.Abort(_('unknown stream encoder: %s') % name) self._encoder = STREAM_ENCODERS[name][0](ui) self._encodername = name def encode(self, data): if not self._encoder: return data return self._encoder.encode(data) def flush(self): if not self._encoder: return b'' return self._encoder.flush() def finish(self): if not self._encoder: return b'' self._encoder.finish() def makeframe(self, requestid, typeid, flags, payload, encoded=False): """Create a frame to be sent out over this stream. Only returns the frame instance. Does not actually send it. """ streamflags = 0 if not self._active: streamflags |= STREAM_FLAG_BEGIN_STREAM self._active = True if encoded: if not self.streamsettingssent: raise error.ProgrammingError( b'attempting to send encoded frame without sending stream ' b'settings') streamflags |= STREAM_FLAG_ENCODING_APPLIED if (typeid == FRAME_TYPE_STREAM_SETTINGS and flags & FLAG_STREAM_ENCODING_SETTINGS_EOS): self.streamsettingssent = True return makeframe(requestid, self.streamid, streamflags, typeid, flags, payload) def makestreamsettingsframe(self, requestid): """Create a stream settings frame for this stream. Returns frame data or None if no stream settings frame is needed or has already been sent. """ if not self._encoder or self.streamsettingssent: return None payload = b''.join(cborutil.streamencode(self._encodername)) return self.makeframe(requestid, FRAME_TYPE_STREAM_SETTINGS, FLAG_STREAM_ENCODING_SETTINGS_EOS, payload) def ensureserverstream(stream): if stream.streamid % 2: raise error.ProgrammingError('server should only write to even ' 'numbered streams; %d is not even' % stream.streamid) DEFAULT_PROTOCOL_SETTINGS = { 'contentencodings': [b'identity'], } class serverreactor(object): """Holds state of a server handling frame-based protocol requests. This class is the "brain" of the unified frame-based protocol server component. While the protocol is stateless from the perspective of requests/commands, something needs to track which frames have been received, what frames to expect, etc. This class is that thing. Instances are modeled as a state machine of sorts. Instances are also reactionary to external events. The point of this class is to encapsulate the state of the connection and the exchange of frames, not to perform work. Instead, callers tell this class when something occurs, like a frame arriving. If that activity is worthy of a follow-up action (say *run a command*), the return value of that handler will say so. I/O and CPU intensive operations are purposefully delegated outside of this class. Consumers are expected to tell instances when events occur. They do so by calling the various ``on*`` methods. These methods return a 2-tuple describing any follow-up action(s) to take. The first element is the name of an action to perform. The second is a data structure (usually a dict) specific to that action that contains more information. e.g. if the server wants to send frames back to the client, the data structure will contain a reference to those frames. Valid actions that consumers can be instructed to take are: sendframes Indicates that frames should be sent to the client. The ``framegen`` key contains a generator of frames that should be sent. The server assumes that all frames are sent to the client. error Indicates that an error occurred. Consumer should probably abort. runcommand Indicates that the consumer should run a wire protocol command. Details of the command to run are given in the data structure. wantframe Indicates that nothing of interest happened and the server is waiting on more frames from the client before anything interesting can be done. noop Indicates no additional action is required. Known Issues ------------ There are no limits to the number of partially received commands or their size. A malicious client could stream command request data and exhaust the server's memory. Partially received commands are not acted upon when end of input is reached. Should the server error if it receives a partial request? Should the client send a message to abort a partially transmitted request to facilitate graceful shutdown? Active requests that haven't been responded to aren't tracked. This means that if we receive a command and instruct its dispatch, another command with its request ID can come in over the wire and there will be a race between who responds to what. """ def __init__(self, ui, deferoutput=False): """Construct a new server reactor. ``deferoutput`` can be used to indicate that no output frames should be instructed to be sent until input has been exhausted. In this mode, events that would normally generate output frames (such as a command response being ready) will instead defer instructing the consumer to send those frames. This is useful for half-duplex transports where the sender cannot receive until all data has been transmitted. """ self._ui = ui self._deferoutput = deferoutput self._state = 'initial' self._nextoutgoingstreamid = 2 self._bufferedframegens = [] # stream id -> stream instance for all active streams from the client. self._incomingstreams = {} self._outgoingstreams = {} # request id -> dict of commands that are actively being received. self._receivingcommands = {} # Request IDs that have been received and are actively being processed. # Once all output for a request has been sent, it is removed from this # set. self._activecommands = set() self._protocolsettingsdecoder = None # Sender protocol settings are optional. Set implied default values. self._sendersettings = dict(DEFAULT_PROTOCOL_SETTINGS) populatestreamencoders() def onframerecv(self, frame): """Process a frame that has been received off the wire. Returns a dict with an ``action`` key that details what action, if any, the consumer should take next. """ if not frame.streamid % 2: self._state = 'errored' return self._makeerrorresult( _('received frame with even numbered stream ID: %d') % frame.streamid) if frame.streamid not in self._incomingstreams: if not frame.streamflags & STREAM_FLAG_BEGIN_STREAM: self._state = 'errored' return self._makeerrorresult( _('received frame on unknown inactive stream without ' 'beginning of stream flag set')) self._incomingstreams[frame.streamid] = inputstream(frame.streamid) if frame.streamflags & STREAM_FLAG_ENCODING_APPLIED: # TODO handle decoding frames self._state = 'errored' raise error.ProgrammingError('support for decoding stream payloads ' 'not yet implemented') if frame.streamflags & STREAM_FLAG_END_STREAM: del self._incomingstreams[frame.streamid] handlers = { 'initial': self._onframeinitial, 'protocol-settings-receiving': self._onframeprotocolsettings, 'idle': self._onframeidle, 'command-receiving': self._onframecommandreceiving, 'errored': self._onframeerrored, } meth = handlers.get(self._state) if not meth: raise error.ProgrammingError('unhandled state: %s' % self._state) return meth(frame) def oncommandresponsereadyobjects(self, stream, requestid, objs): """Signal that objects are ready to be sent to the client. ``objs`` is an iterable of objects (typically a generator) that will be encoded via CBOR and added to frames, which will be sent to the client. """ ensureserverstream(stream) # A more robust solution would be to check for objs.{next,__next__}. if isinstance(objs, list): objs = iter(objs) # We need to take care over exception handling. Uncaught exceptions # when generating frames could lead to premature end of the frame # stream and the possibility of the server or client process getting # in a bad state. # # Keep in mind that if ``objs`` is a generator, advancing it could # raise exceptions that originated in e.g. wire protocol command # functions. That is why we differentiate between exceptions raised # when iterating versus other exceptions that occur. # # In all cases, when the function finishes, the request is fully # handled and no new frames for it should be seen. def sendframes(): emitted = False alternatelocationsent = False emitter = bufferingcommandresponseemitter(stream, requestid) while True: try: o = next(objs) except StopIteration: for frame in emitter.send(None): yield frame if emitted: for frame in createcommandresponseeosframes( stream, requestid): yield frame break except error.WireprotoCommandError as e: for frame in createcommanderrorresponse( stream, requestid, e.message, e.messageargs): yield frame break except Exception as e: for frame in createerrorframe( stream, requestid, '%s' % stringutil.forcebytestr(e), errtype='server'): yield frame break try: # Alternate location responses can only be the first and # only object in the output stream. if isinstance(o, wireprototypes.alternatelocationresponse): if emitted: raise error.ProgrammingError( 'alternatelocationresponse seen after initial ' 'output object') frame = stream.makestreamsettingsframe(requestid) if frame: yield frame yield createalternatelocationresponseframe( stream, requestid, o) alternatelocationsent = True emitted = True continue if alternatelocationsent: raise error.ProgrammingError( 'object follows alternatelocationresponse') if not emitted: # Frame is optional. frame = stream.makestreamsettingsframe(requestid) if frame: yield frame # May be None if empty frame (due to encoding). frame = createcommandresponseokframe(stream, requestid) if frame: yield frame emitted = True # Objects emitted by command functions can be serializable # data structures or special types. # TODO consider extracting the content normalization to a # standalone function, as it may be useful for e.g. cachers. # A pre-encoded object is sent directly to the emitter. if isinstance(o, wireprototypes.encodedresponse): for frame in emitter.send(o.data): yield frame elif isinstance( o, wireprototypes.indefinitebytestringresponse): for chunk in cborutil.streamencodebytestringfromiter( o.chunks): for frame in emitter.send(chunk): yield frame # A regular object is CBOR encoded. else: for chunk in cborutil.streamencode(o): for frame in emitter.send(chunk): yield frame except Exception as e: for frame in createerrorframe(stream, requestid, '%s' % e, errtype='server'): yield frame break self._activecommands.remove(requestid) return self._handlesendframes(sendframes()) def oninputeof(self): """Signals that end of input has been received. No more frames will be received. All pending activity should be completed. """ # TODO should we do anything about in-flight commands? if not self._deferoutput or not self._bufferedframegens: return 'noop', {} # If we buffered all our responses, emit those. def makegen(): for gen in self._bufferedframegens: for frame in gen: yield frame return 'sendframes', { 'framegen': makegen(), } def _handlesendframes(self, framegen): if self._deferoutput: self._bufferedframegens.append(framegen) return 'noop', {} else: return 'sendframes', { 'framegen': framegen, } def onservererror(self, stream, requestid, msg): ensureserverstream(stream) def sendframes(): for frame in createerrorframe(stream, requestid, msg, errtype='server'): yield frame self._activecommands.remove(requestid) return self._handlesendframes(sendframes()) def oncommanderror(self, stream, requestid, message, args=None): """Called when a command encountered an error before sending output.""" ensureserverstream(stream) def sendframes(): for frame in createcommanderrorresponse(stream, requestid, message, args): yield frame self._activecommands.remove(requestid) return self._handlesendframes(sendframes()) def makeoutputstream(self): """Create a stream to be used for sending data to the client. If this is called before protocol settings frames are received, we don't know what stream encodings are supported by the client and we will default to identity. """ streamid = self._nextoutgoingstreamid self._nextoutgoingstreamid += 2 s = outputstream(streamid) self._outgoingstreams[streamid] = s # Always use the *server's* preferred encoder over the client's, # as servers have more to lose from sub-optimal encoders being used. for name in STREAM_ENCODERS_ORDER: if name in self._sendersettings['contentencodings']: s.setencoder(self._ui, name) break return s def _makeerrorresult(self, msg): return 'error', { 'message': msg, } def _makeruncommandresult(self, requestid): entry = self._receivingcommands[requestid] if not entry['requestdone']: self._state = 'errored' raise error.ProgrammingError('should not be called without ' 'requestdone set') del self._receivingcommands[requestid] if self._receivingcommands: self._state = 'command-receiving' else: self._state = 'idle' # Decode the payloads as CBOR. entry['payload'].seek(0) request = cborutil.decodeall(entry['payload'].getvalue())[0] if b'name' not in request: self._state = 'errored' return self._makeerrorresult( _('command request missing "name" field')) if b'args' not in request: request[b'args'] = {} assert requestid not in self._activecommands self._activecommands.add(requestid) return 'runcommand', { 'requestid': requestid, 'command': request[b'name'], 'args': request[b'args'], 'redirect': request.get(b'redirect'), 'data': entry['data'].getvalue() if entry['data'] else None, } def _makewantframeresult(self): return 'wantframe', { 'state': self._state, } def _validatecommandrequestframe(self, frame): new = frame.flags & FLAG_COMMAND_REQUEST_NEW continuation = frame.flags & FLAG_COMMAND_REQUEST_CONTINUATION if new and continuation: self._state = 'errored' return self._makeerrorresult( _('received command request frame with both new and ' 'continuation flags set')) if not new and not continuation: self._state = 'errored' return self._makeerrorresult( _('received command request frame with neither new nor ' 'continuation flags set')) def _onframeinitial(self, frame): # Called when we receive a frame when in the "initial" state. if frame.typeid == FRAME_TYPE_SENDER_PROTOCOL_SETTINGS: self._state = 'protocol-settings-receiving' self._protocolsettingsdecoder = cborutil.bufferingdecoder() return self._onframeprotocolsettings(frame) elif frame.typeid == FRAME_TYPE_COMMAND_REQUEST: self._state = 'idle' return self._onframeidle(frame) else: self._state = 'errored' return self._makeerrorresult( _('expected sender protocol settings or command request ' 'frame; got %d') % frame.typeid) def _onframeprotocolsettings(self, frame): assert self._state == 'protocol-settings-receiving' assert self._protocolsettingsdecoder is not None if frame.typeid != FRAME_TYPE_SENDER_PROTOCOL_SETTINGS: self._state = 'errored' return self._makeerrorresult( _('expected sender protocol settings frame; got %d') % frame.typeid) more = frame.flags & FLAG_SENDER_PROTOCOL_SETTINGS_CONTINUATION eos = frame.flags & FLAG_SENDER_PROTOCOL_SETTINGS_EOS if more and eos: self._state = 'errored' return self._makeerrorresult( _('sender protocol settings frame cannot have both ' 'continuation and end of stream flags set')) if not more and not eos: self._state = 'errored' return self._makeerrorresult( _('sender protocol settings frame must have continuation or ' 'end of stream flag set')) # TODO establish limits for maximum amount of data that can be # buffered. try: self._protocolsettingsdecoder.decode(frame.payload) except Exception as e: self._state = 'errored' return self._makeerrorresult( _('error decoding CBOR from sender protocol settings frame: %s') % stringutil.forcebytestr(e)) if more: return self._makewantframeresult() assert eos decoded = self._protocolsettingsdecoder.getavailable() self._protocolsettingsdecoder = None if not decoded: self._state = 'errored' return self._makeerrorresult( _('sender protocol settings frame did not contain CBOR data')) elif len(decoded) > 1: self._state = 'errored' return self._makeerrorresult( _('sender protocol settings frame contained multiple CBOR ' 'values')) d = decoded[0] if b'contentencodings' in d: self._sendersettings['contentencodings'] = d[b'contentencodings'] self._state = 'idle' return self._makewantframeresult() def _onframeidle(self, frame): # The only frame type that should be received in this state is a # command request. if frame.typeid != FRAME_TYPE_COMMAND_REQUEST: self._state = 'errored' return self._makeerrorresult( _('expected command request frame; got %d') % frame.typeid) res = self._validatecommandrequestframe(frame) if res: return res if frame.requestid in self._receivingcommands: self._state = 'errored' return self._makeerrorresult( _('request with ID %d already received') % frame.requestid) if frame.requestid in self._activecommands: self._state = 'errored' return self._makeerrorresult( _('request with ID %d is already active') % frame.requestid) new = frame.flags & FLAG_COMMAND_REQUEST_NEW moreframes = frame.flags & FLAG_COMMAND_REQUEST_MORE_FRAMES expectingdata = frame.flags & FLAG_COMMAND_REQUEST_EXPECT_DATA if not new: self._state = 'errored' return self._makeerrorresult( _('received command request frame without new flag set')) payload = util.bytesio() payload.write(frame.payload) self._receivingcommands[frame.requestid] = { 'payload': payload, 'data': None, 'requestdone': not moreframes, 'expectingdata': bool(expectingdata), } # This is the final frame for this request. Dispatch it. if not moreframes and not expectingdata: return self._makeruncommandresult(frame.requestid) assert moreframes or expectingdata self._state = 'command-receiving' return self._makewantframeresult() def _onframecommandreceiving(self, frame): if frame.typeid == FRAME_TYPE_COMMAND_REQUEST: # Process new command requests as such. if frame.flags & FLAG_COMMAND_REQUEST_NEW: return self._onframeidle(frame) res = self._validatecommandrequestframe(frame) if res: return res # All other frames should be related to a command that is currently # receiving but is not active. if frame.requestid in self._activecommands: self._state = 'errored' return self._makeerrorresult( _('received frame for request that is still active: %d') % frame.requestid) if frame.requestid not in self._receivingcommands: self._state = 'errored' return self._makeerrorresult( _('received frame for request that is not receiving: %d') % frame.requestid) entry = self._receivingcommands[frame.requestid] if frame.typeid == FRAME_TYPE_COMMAND_REQUEST: moreframes = frame.flags & FLAG_COMMAND_REQUEST_MORE_FRAMES expectingdata = bool(frame.flags & FLAG_COMMAND_REQUEST_EXPECT_DATA) if entry['requestdone']: self._state = 'errored' return self._makeerrorresult( _('received command request frame when request frames ' 'were supposedly done')) if expectingdata != entry['expectingdata']: self._state = 'errored' return self._makeerrorresult( _('mismatch between expect data flag and previous frame')) entry['payload'].write(frame.payload) if not moreframes: entry['requestdone'] = True if not moreframes and not expectingdata: return self._makeruncommandresult(frame.requestid) return self._makewantframeresult() elif frame.typeid == FRAME_TYPE_COMMAND_DATA: if not entry['expectingdata']: self._state = 'errored' return self._makeerrorresult(_( 'received command data frame for request that is not ' 'expecting data: %d') % frame.requestid) if entry['data'] is None: entry['data'] = util.bytesio() return self._handlecommanddataframe(frame, entry) else: self._state = 'errored' return self._makeerrorresult(_( 'received unexpected frame type: %d') % frame.typeid) def _handlecommanddataframe(self, frame, entry): assert frame.typeid == FRAME_TYPE_COMMAND_DATA # TODO support streaming data instead of buffering it. entry['data'].write(frame.payload) if frame.flags & FLAG_COMMAND_DATA_CONTINUATION: return self._makewantframeresult() elif frame.flags & FLAG_COMMAND_DATA_EOS: entry['data'].seek(0) return self._makeruncommandresult(frame.requestid) else: self._state = 'errored' return self._makeerrorresult(_('command data frame without ' 'flags')) def _onframeerrored(self, frame): return self._makeerrorresult(_('server already errored')) class commandrequest(object): """Represents a request to run a command.""" def __init__(self, requestid, name, args, datafh=None, redirect=None): self.requestid = requestid self.name = name self.args = args self.datafh = datafh self.redirect = redirect self.state = 'pending' class clientreactor(object): """Holds state of a client issuing frame-based protocol requests. This is like ``serverreactor`` but for client-side state. Each instance is bound to the lifetime of a connection. For persistent connection transports using e.g. TCP sockets and speaking the raw framing protocol, there will be a single instance for the lifetime of the TCP socket. For transports where there are multiple discrete interactions (say tunneled within in HTTP request), there will be a separate instance for each distinct interaction. Consumers are expected to tell instances when events occur by calling various methods. These methods return a 2-tuple describing any follow-up action(s) to take. The first element is the name of an action to perform. The second is a data structure (usually a dict) specific to that action that contains more information. e.g. if the reactor wants to send frames to the server, the data structure will contain a reference to those frames. Valid actions that consumers can be instructed to take are: noop Indicates no additional action is required. sendframes Indicates that frames should be sent to the server. The ``framegen`` key contains a generator of frames that should be sent. The reactor assumes that all frames in this generator are sent to the server. error Indicates that an error occurred. The ``message`` key contains an error message describing the failure. responsedata Indicates a response to a previously-issued command was received. The ``request`` key contains the ``commandrequest`` instance that represents the request this data is for. The ``data`` key contains the decoded data from the server. ``expectmore`` and ``eos`` evaluate to True when more response data is expected to follow or we're at the end of the response stream, respectively. """ def __init__(self, ui, hasmultiplesend=False, buffersends=True, clientcontentencoders=None): """Create a new instance. ``hasmultiplesend`` indicates whether multiple sends are supported by the transport. When True, it is possible to send commands immediately instead of buffering until the caller signals an intent to finish a send operation. ``buffercommands`` indicates whether sends should be buffered until the last request has been issued. ``clientcontentencoders`` is an iterable of content encoders the client will advertise to the server and that the server can use for encoding data. If not defined, the client will not advertise content encoders to the server. """ self._ui = ui self._hasmultiplesend = hasmultiplesend self._buffersends = buffersends self._clientcontentencoders = clientcontentencoders self._canissuecommands = True self._cansend = True self._protocolsettingssent = False self._nextrequestid = 1 # We only support a single outgoing stream for now. self._outgoingstream = outputstream(1) self._pendingrequests = collections.deque() self._activerequests = {} self._incomingstreams = {} self._streamsettingsdecoders = {} populatestreamencoders() def callcommand(self, name, args, datafh=None, redirect=None): """Request that a command be executed. Receives the command name, a dict of arguments to pass to the command, and an optional file object containing the raw data for the command. Returns a 3-tuple of (request, action, action data). """ if not self._canissuecommands: raise error.ProgrammingError('cannot issue new commands') requestid = self._nextrequestid self._nextrequestid += 2 request = commandrequest(requestid, name, args, datafh=datafh, redirect=redirect) if self._buffersends: self._pendingrequests.append(request) return request, 'noop', {} else: if not self._cansend: raise error.ProgrammingError('sends cannot be performed on ' 'this instance') if not self._hasmultiplesend: self._cansend = False self._canissuecommands = False return request, 'sendframes', { 'framegen': self._makecommandframes(request), } def flushcommands(self): """Request that all queued commands be sent. If any commands are buffered, this will instruct the caller to send them over the wire. If no commands are buffered it instructs the client to no-op. If instances aren't configured for multiple sends, no new command requests are allowed after this is called. """ if not self._pendingrequests: return 'noop', {} if not self._cansend: raise error.ProgrammingError('sends cannot be performed on this ' 'instance') # If the instance only allows sending once, mark that we have fired # our one shot. if not self._hasmultiplesend: self._canissuecommands = False self._cansend = False def makeframes(): while self._pendingrequests: request = self._pendingrequests.popleft() for frame in self._makecommandframes(request): yield frame return 'sendframes', { 'framegen': makeframes(), } def _makecommandframes(self, request): """Emit frames to issue a command request. As a side-effect, update request accounting to reflect its changed state. """ self._activerequests[request.requestid] = request request.state = 'sending' if not self._protocolsettingssent and self._clientcontentencoders: self._protocolsettingssent = True payload = b''.join(cborutil.streamencode({ b'contentencodings': self._clientcontentencoders, })) yield self._outgoingstream.makeframe( requestid=request.requestid, typeid=FRAME_TYPE_SENDER_PROTOCOL_SETTINGS, flags=FLAG_SENDER_PROTOCOL_SETTINGS_EOS, payload=payload) res = createcommandframes(self._outgoingstream, request.requestid, request.name, request.args, datafh=request.datafh, redirect=request.redirect) for frame in res: yield frame request.state = 'sent' def onframerecv(self, frame): """Process a frame that has been received off the wire. Returns a 2-tuple of (action, meta) describing further action the caller needs to take as a result of receiving this frame. """ if frame.streamid % 2: return 'error', { 'message': ( _('received frame with odd numbered stream ID: %d') % frame.streamid), } if frame.streamid not in self._incomingstreams: if not frame.streamflags & STREAM_FLAG_BEGIN_STREAM: return 'error', { 'message': _('received frame on unknown stream ' 'without beginning of stream flag set'), } self._incomingstreams[frame.streamid] = inputstream( frame.streamid) stream = self._incomingstreams[frame.streamid] # If the payload is encoded, ask the stream to decode it. We # merely substitute the decoded result into the frame payload as # if it had been transferred all along. if frame.streamflags & STREAM_FLAG_ENCODING_APPLIED: frame.payload = stream.decode(frame.payload) if frame.streamflags & STREAM_FLAG_END_STREAM: del self._incomingstreams[frame.streamid] if frame.typeid == FRAME_TYPE_STREAM_SETTINGS: return self._onstreamsettingsframe(frame) if frame.requestid not in self._activerequests: return 'error', { 'message': (_('received frame for inactive request ID: %d') % frame.requestid), } request = self._activerequests[frame.requestid] request.state = 'receiving' handlers = { FRAME_TYPE_COMMAND_RESPONSE: self._oncommandresponseframe, FRAME_TYPE_ERROR_RESPONSE: self._onerrorresponseframe, } meth = handlers.get(frame.typeid) if not meth: raise error.ProgrammingError('unhandled frame type: %d' % frame.typeid) return meth(request, frame) def _onstreamsettingsframe(self, frame): assert frame.typeid == FRAME_TYPE_STREAM_SETTINGS more = frame.flags & FLAG_STREAM_ENCODING_SETTINGS_CONTINUATION eos = frame.flags & FLAG_STREAM_ENCODING_SETTINGS_EOS if more and eos: return 'error', { 'message': (_('stream encoding settings frame cannot have both ' 'continuation and end of stream flags set')), } if not more and not eos: return 'error', { 'message': _('stream encoding settings frame must have ' 'continuation or end of stream flag set'), } if frame.streamid not in self._streamsettingsdecoders: decoder = cborutil.bufferingdecoder() self._streamsettingsdecoders[frame.streamid] = decoder decoder = self._streamsettingsdecoders[frame.streamid] try: decoder.decode(frame.payload) except Exception as e: return 'error', { 'message': (_('error decoding CBOR from stream encoding ' 'settings frame: %s') % stringutil.forcebytestr(e)), } if more: return 'noop', {} assert eos decoded = decoder.getavailable() del self._streamsettingsdecoders[frame.streamid] if not decoded: return 'error', { 'message': _('stream encoding settings frame did not contain ' 'CBOR data'), } try: self._incomingstreams[frame.streamid].setdecoder(self._ui, decoded[0], decoded[1:]) except Exception as e: return 'error', { 'message': (_('error setting stream decoder: %s') % stringutil.forcebytestr(e)), } return 'noop', {} def _oncommandresponseframe(self, request, frame): if frame.flags & FLAG_COMMAND_RESPONSE_EOS: request.state = 'received' del self._activerequests[request.requestid] return 'responsedata', { 'request': request, 'expectmore': frame.flags & FLAG_COMMAND_RESPONSE_CONTINUATION, 'eos': frame.flags & FLAG_COMMAND_RESPONSE_EOS, 'data': frame.payload, } def _onerrorresponseframe(self, request, frame): request.state = 'errored' del self._activerequests[request.requestid] # The payload should be a CBOR map. m = cborutil.decodeall(frame.payload)[0] return 'error', { 'request': request, 'type': m['type'], 'message': m['message'], }