wireprotov2: add support for more response types

This adds types to represent error and generator responses from
server commands.

Differential Revision: https://phab.mercurial-scm.org/D3388

mercurial/wireprotoframing.py

@@ -1,1078 +1,1167
 # wireprotoframing.py - unified framing protocol for wire protocol
 #
 # Copyright 2018 Gregory Szorc <[e-mail]>
 #
 # 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,
     cbor,
 )
 from . import (
     encoding,
     error,
     util,
 )
 from .utils import (
     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_STREAM_SETTINGS = 0x08
 
 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'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,
 }
 
 # 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_STREAM_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 = cbor.dumps(stringutil.evalpythonliteral(payload[5:]),
                              canonical=True)
 
     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):
     """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
 
     data = cbor.dumps(data, canonical=True)
 
     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 createcommandresponseframesfrombytes(stream, requestid, data,
                                          maxframesize=DEFAULT_MAX_FRAME_SIZE):
     """Create a raw frame to send a bytes response from static bytes input.
 
     Returns a generator of bytearrays.
     """
     # Automatically send the overall CBOR response map.
     overall = cbor.dumps({b'status': b'ok'}, canonical=True)
     if len(overall) > maxframesize:
         raise error.ProgrammingError('not yet implemented')
 
     # Simple case where we can fit the full response in a single frame.
     if len(overall) + len(data) <= maxframesize:
         flags = FLAG_COMMAND_RESPONSE_EOS
         yield stream.makeframe(requestid=requestid,
                                typeid=FRAME_TYPE_COMMAND_RESPONSE,
                                flags=flags,
                                payload=overall + data)
         return
 
     # It's easier to send the overall CBOR map in its own frame than to track
     # offsets.
     yield stream.makeframe(requestid=requestid,
                            typeid=FRAME_TYPE_COMMAND_RESPONSE,
                            flags=FLAG_COMMAND_RESPONSE_CONTINUATION,
                            payload=overall)
 
     offset = 0
     while True:
         chunk = data[offset:offset + maxframesize]
         offset += len(chunk)
         done = offset == len(data)
 
         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)
 
         if done:
             break
 
+def createbytesresponseframesfromgen(stream, requestid, gen,
+                                     maxframesize=DEFAULT_MAX_FRAME_SIZE):
+    overall = cbor.dumps({b'status': b'ok'}, canonical=True)
+
+    yield stream.makeframe(requestid=requestid,
+                           typeid=FRAME_TYPE_COMMAND_RESPONSE,
+                           flags=FLAG_COMMAND_RESPONSE_CONTINUATION,
+                           payload=overall)
+
+    cb = util.chunkbuffer(gen)
+
+    flags = 0
+
+    while True:
+        chunk = cb.read(maxframesize)
+        if not chunk:
+            break
+
+        yield stream.makeframe(requestid=requestid,
+                               typeid=FRAME_TYPE_COMMAND_RESPONSE,
+                               flags=flags,
+                               payload=chunk)
+
+        flags |= FLAG_COMMAND_RESPONSE_CONTINUATION
+
+    flags ^= FLAG_COMMAND_RESPONSE_CONTINUATION
+    flags |= FLAG_COMMAND_RESPONSE_EOS
+    yield stream.makeframe(requestid=requestid,
+                           typeid=FRAME_TYPE_COMMAND_RESPONSE,
+                           flags=flags,
+                           payload=b'')
+
+def createcommanderrorresponse(stream, requestid, message, args=None):
+    m = {
+        b'status': b'error',
+        b'error': {
+            b'message': message,
+        }
+    }
+
+    if args:
+        m[b'error'][b'args'] = args
+
+    overall = cbor.dumps(m, canonical=True)
+
+    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 = cbor.dumps({
         b'type': errtype,
         b'message': [{b'msg': msg}],
     }, canonical=True)
 
     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 = cbor.dumps(atomdicts, canonical=True)
 
     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 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)
 
 def ensureserverstream(stream):
     if stream.streamid % 2:
         raise error.ProgrammingError('server should only write to even '
                                      'numbered streams; %d is not even' %
                                      stream.streamid)
 
 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, 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._deferoutput = deferoutput
         self._state = 'idle'
         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()
 
     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] = stream(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 = {
             '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 oncommandresponseready(self, stream, requestid, data):
         """Signal that a bytes response is ready to be sent to the client.
 
         The raw bytes response is passed as an argument.
         """
         ensureserverstream(stream)
 
         def sendframes():
             for frame in createcommandresponseframesfrombytes(stream, requestid,
                                                               data):
                 yield frame
 
             self._activecommands.remove(requestid)
 
         result = sendframes()
 
         if self._deferoutput:
             self._bufferedframegens.append(result)
             return 'noop', {}
         else:
             return 'sendframes', {
                 'framegen': result,
             }
 
+    def oncommandresponsereadygen(self, stream, requestid, gen):
+        """Signal that a bytes response is ready, with data as a generator."""
+        ensureserverstream(stream)
+
+        def sendframes():
+            for frame in createbytesresponseframesfromgen(stream, requestid,
+                                                          gen):
+                yield frame
+
+            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)
 
-        return 'sendframes', {
-            'framegen': createerrorframe(stream, requestid, msg,
-                                         errtype='server'),
-        }
+        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."""
         streamid = self._nextoutgoingstreamid
         self._nextoutgoingstreamid += 2
 
         s = stream(streamid)
         self._outgoingstreams[streamid] = s
 
         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 = cbor.load(entry['payload'])
 
         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'],
             '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 _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):
         self.requestid = requestid
         self.name = name
         self.args = args
         self.datafh = datafh
         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.
     """
     def __init__(self, hasmultiplesend=False, buffersends=True):
         """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.
         """
         self._hasmultiplesend = hasmultiplesend
         self._buffersends = buffersends
 
         self._canissuecommands = True
         self._cansend = True
 
         self._nextrequestid = 1
         # We only support a single outgoing stream for now.
         self._outgoingstream = stream(1)
         self._pendingrequests = collections.deque()
         self._activerequests = {}
         self._incomingstreams = {}
 
     def callcommand(self, name, args, datafh=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)
 
         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'
 
         res = createcommandframes(self._outgoingstream,
                                   request.requestid,
                                   request.name,
                                   request.args,
                                   request.datafh)
 
         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] = stream(frame.streamid)
 
         if frame.streamflags & STREAM_FLAG_ENCODING_APPLIED:
             raise error.ProgrammingError('support for decoding stream '
                                          'payloads not yet implemneted')
 
         if frame.streamflags & STREAM_FLAG_END_STREAM:
             del self._incomingstreams[frame.streamid]
 
         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 _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 = cbor.loads(frame.payload)
 
         return 'error', {
             'request': request,
             'type': m['type'],
             'message': m['message'],
         }

mercurial/wireprototypes.py

@@ -1,227 +1,243
 # Copyright 2018 Gregory Szorc <[e-mail]>
 #
 # 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
 
 from .node import (
     bin,
     hex,
 )
 from .thirdparty.zope import (
     interface as zi,
 )
 
 # Names of the SSH protocol implementations.
 SSHV1 = 'ssh-v1'
 # These are advertised over the wire. Increment the counters at the end
 # to reflect BC breakages.
 SSHV2 = 'exp-ssh-v2-0001'
 HTTP_WIREPROTO_V2 = 'exp-http-v2-0001'
 
 # All available wire protocol transports.
 TRANSPORTS = {
     SSHV1: {
         'transport': 'ssh',
         'version': 1,
     },
     SSHV2: {
         'transport': 'ssh',
         # TODO mark as version 2 once all commands are implemented.
         'version': 1,
     },
     'http-v1': {
         'transport': 'http',
         'version': 1,
     },
     HTTP_WIREPROTO_V2: {
         'transport': 'http',
         'version': 2,
     }
 }
 
 class bytesresponse(object):
     """A wire protocol response consisting of raw bytes."""
     def __init__(self, data):
         self.data = data
 
 class ooberror(object):
     """wireproto reply: failure of a batch of operation
 
     Something failed during a batch call. The error message is stored in
     `self.message`.
     """
     def __init__(self, message):
         self.message = message
 
 class pushres(object):
     """wireproto reply: success with simple integer return
 
     The call was successful and returned an integer contained in `self.res`.
     """
     def __init__(self, res, output):
         self.res = res
         self.output = output
 
 class pusherr(object):
     """wireproto reply: failure
 
     The call failed. The `self.res` attribute contains the error message.
     """
     def __init__(self, res, output):
         self.res = res
         self.output = output
 
 class streamres(object):
     """wireproto reply: binary stream
 
     The call was successful and the result is a stream.
 
     Accepts a generator containing chunks of data to be sent to the client.
 
     ``prefer_uncompressed`` indicates that the data is expected to be
     uncompressable and that the stream should therefore use the ``none``
     engine.
     """
     def __init__(self, gen=None, prefer_uncompressed=False):
         self.gen = gen
         self.prefer_uncompressed = prefer_uncompressed
 
 class streamreslegacy(object):
     """wireproto reply: uncompressed binary stream
 
     The call was successful and the result is a stream.
 
     Accepts a generator containing chunks of data to be sent to the client.
 
     Like ``streamres``, but sends an uncompressed data for "version 1" clients
     using the application/mercurial-0.1 media type.
     """
     def __init__(self, gen=None):
         self.gen = gen
 
 class cborresponse(object):
     """Encode the response value as CBOR."""
     def __init__(self, v):
         self.value = v
 
+class v2errorresponse(object):
+    """Represents a command error for version 2 transports."""
+    def __init__(self, message, args=None):
+        self.message = message
+        self.args = args
+
+class v2streamingresponse(object):
+    """A response whose data is supplied by a generator.
+
+    The generator can either consist of data structures to CBOR
+    encode or a stream of already-encoded bytes.
+    """
+    def __init__(self, gen, compressible=True):
+        self.gen = gen
+        self.compressible = compressible
+
 # list of nodes encoding / decoding
 def decodelist(l, sep=' '):
     if l:
         return [bin(v) for v in  l.split(sep)]
     return []
 
 def encodelist(l, sep=' '):
     try:
         return sep.join(map(hex, l))
     except TypeError:
         raise
 
 # batched call argument encoding
 
 def escapebatcharg(plain):
     return (plain
             .replace(':', ':c')
             .replace(',', ':o')
             .replace(';', ':s')
             .replace('=', ':e'))
 
 def unescapebatcharg(escaped):
     return (escaped
             .replace(':e', '=')
             .replace(':s', ';')
             .replace(':o', ',')
             .replace(':c', ':'))
 
 # mapping of options accepted by getbundle and their types
 #
 # Meant to be extended by extensions. It is extensions responsibility to ensure
 # such options are properly processed in exchange.getbundle.
 #
 # supported types are:
 #
 # :nodes: list of binary nodes
 # :csv:   list of comma-separated values
 # :scsv:  list of comma-separated values return as set
 # :plain: string with no transformation needed.
 GETBUNDLE_ARGUMENTS = {
     'heads':  'nodes',
     'bookmarks': 'boolean',
     'common': 'nodes',
     'obsmarkers': 'boolean',
     'phases': 'boolean',
     'bundlecaps': 'scsv',
     'listkeys': 'csv',
     'cg': 'boolean',
     'cbattempted': 'boolean',
     'stream': 'boolean',
 }
 
 class baseprotocolhandler(zi.Interface):
     """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.
     """
 
     name = zi.Attribute(
         """The name of the protocol implementation.
 
         Used for uniquely identifying the transport type.
         """)
 
     def getargs(args):
         """return the value for arguments in <args>
 
         For version 1 transports, returns a list of values in the same
         order they appear in ``args``. For version 2 transports, returns
         a dict mapping argument name to value.
         """
 
     def getprotocaps():
         """Returns the list of protocol-level capabilities of client
 
         Returns a list of capabilities as declared by the client for
         the current request (or connection for stateful protocol handlers)."""
 
     def getpayload():
         """Provide a generator for the raw payload.
 
         The caller is responsible for ensuring that the full payload is
         processed.
         """
 
     def mayberedirectstdio():
         """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.
         """
 
     def client():
         """Returns a string representation of this client (as bytes)."""
 
     def addcapabilities(repo, caps):
         """Adds advertised capabilities specific to this protocol.
 
         Receives the list of capabilities collected so far.
 
         Returns a list of capabilities. The passed in argument can be returned.
         """
 
     def checkperm(perm):
         """Validate that the client has permissions to perform a request.
 
         The argument is the permission required to proceed. If the client
         doesn't have that permission, the exception should raise or abort
         in a protocol specific manner.
         """

mercurial/wireprotov2server.py

@@ -1,480 +1,489
 # Copyright 21 May 2005 - (c) 2005 Jake Edge <[e-mail]>
 # Copyright 2005-2007 Matt Mackall <[e-mail]>
 #
 # 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 contextlib
 
 from .i18n import _
 from .thirdparty import (
     cbor,
 )
 from .thirdparty.zope import (
     interface as zi,
 )
 from . import (
     encoding,
     error,
     pycompat,
     streamclone,
     util,
     wireproto,
     wireprotoframing,
     wireprototypes,
 )
 
 FRAMINGTYPE = b'application/mercurial-exp-framing-0005'
 
 HTTP_WIREPROTO_V2 = wireprototypes.HTTP_WIREPROTO_V2
 
 def handlehttpv2request(rctx, req, res, checkperm, urlparts):
     from .hgweb import common as hgwebcommon
 
     # URL space looks like: <permissions>/<command>, where <permission> can
     # be ``ro`` or ``rw`` to signal read-only or read-write, respectively.
 
     # Root URL does nothing meaningful... yet.
     if not urlparts:
         res.status = b'200 OK'
         res.headers[b'Content-Type'] = b'text/plain'
         res.setbodybytes(_('HTTP version 2 API handler'))
         return
 
     if len(urlparts) == 1:
         res.status = b'404 Not Found'
         res.headers[b'Content-Type'] = b'text/plain'
         res.setbodybytes(_('do not know how to process %s\n') %
                          req.dispatchpath)
         return
 
     permission, command = urlparts[0:2]
 
     if permission not in (b'ro', b'rw'):
         res.status = b'404 Not Found'
         res.headers[b'Content-Type'] = b'text/plain'
         res.setbodybytes(_('unknown permission: %s') % permission)
         return
 
     if req.method != 'POST':
         res.status = b'405 Method Not Allowed'
         res.headers[b'Allow'] = b'POST'
         res.setbodybytes(_('commands require POST requests'))
         return
 
     # At some point we'll want to use our own API instead of recycling the
     # behavior of version 1 of the wire protocol...
     # TODO return reasonable responses - not responses that overload the
     # HTTP status line message for error reporting.
     try:
         checkperm(rctx, req, 'pull' if permission == b'ro' else 'push')
     except hgwebcommon.ErrorResponse as e:
         res.status = hgwebcommon.statusmessage(e.code, pycompat.bytestr(e))
         for k, v in e.headers:
             res.headers[k] = v
         res.setbodybytes('permission denied')
         return
 
     # We have a special endpoint to reflect the request back at the client.
     if command == b'debugreflect':
         _processhttpv2reflectrequest(rctx.repo.ui, rctx.repo, req, res)
         return
 
     # Extra commands that we handle that aren't really wire protocol
     # commands. Think extra hard before making this hackery available to
     # extension.
     extracommands = {'multirequest'}
 
     if command not in wireproto.commandsv2 and command not in extracommands:
         res.status = b'404 Not Found'
         res.headers[b'Content-Type'] = b'text/plain'
         res.setbodybytes(_('unknown wire protocol command: %s\n') % command)
         return
 
     repo = rctx.repo
     ui = repo.ui
 
     proto = httpv2protocolhandler(req, ui)
 
     if (not wireproto.commandsv2.commandavailable(command, proto)
         and command not in extracommands):
         res.status = b'404 Not Found'
         res.headers[b'Content-Type'] = b'text/plain'
         res.setbodybytes(_('invalid wire protocol command: %s') % command)
         return
 
     # TODO consider cases where proxies may add additional Accept headers.
     if req.headers.get(b'Accept') != FRAMINGTYPE:
         res.status = b'406 Not Acceptable'
         res.headers[b'Content-Type'] = b'text/plain'
         res.setbodybytes(_('client MUST specify Accept header with value: %s\n')
                            % FRAMINGTYPE)
         return
 
     if req.headers.get(b'Content-Type') != FRAMINGTYPE:
         res.status = b'415 Unsupported Media Type'
         # TODO we should send a response with appropriate media type,
         # since client does Accept it.
         res.headers[b'Content-Type'] = b'text/plain'
         res.setbodybytes(_('client MUST send Content-Type header with '
                            'value: %s\n') % FRAMINGTYPE)
         return
 
     _processhttpv2request(ui, repo, req, res, permission, command, proto)
 
 def _processhttpv2reflectrequest(ui, repo, req, res):
     """Reads unified frame protocol request and dumps out state to client.
 
     This special endpoint can be used to help debug the wire protocol.
 
     Instead of routing the request through the normal dispatch mechanism,
     we instead read all frames, decode them, and feed them into our state
     tracker. We then dump the log of all that activity back out to the
     client.
     """
     import json
 
     # Reflection APIs have a history of being abused, accidentally disclosing
     # sensitive data, etc. So we have a config knob.
     if not ui.configbool('experimental', 'web.api.debugreflect'):
         res.status = b'404 Not Found'
         res.headers[b'Content-Type'] = b'text/plain'
         res.setbodybytes(_('debugreflect service not available'))
         return
 
     # We assume we have a unified framing protocol request body.
 
     reactor = wireprotoframing.serverreactor()
     states = []
 
     while True:
         frame = wireprotoframing.readframe(req.bodyfh)
 
         if not frame:
             states.append(b'received: <no frame>')
             break
 
         states.append(b'received: %d %d %d %s' % (frame.typeid, frame.flags,
                                                   frame.requestid,
                                                   frame.payload))
 
         action, meta = reactor.onframerecv(frame)
         states.append(json.dumps((action, meta), sort_keys=True,
                                  separators=(', ', ': ')))
 
     action, meta = reactor.oninputeof()
     meta['action'] = action
     states.append(json.dumps(meta, sort_keys=True, separators=(', ',': ')))
 
     res.status = b'200 OK'
     res.headers[b'Content-Type'] = b'text/plain'
     res.setbodybytes(b'\n'.join(states))
 
 def _processhttpv2request(ui, repo, req, res, authedperm, reqcommand, proto):
     """Post-validation handler for HTTPv2 requests.
 
     Called when the HTTP request contains unified frame-based protocol
     frames for evaluation.
     """
     # TODO Some HTTP clients are full duplex and can receive data before
     # the entire request is transmitted. Figure out a way to indicate support
     # for that so we can opt into full duplex mode.
     reactor = wireprotoframing.serverreactor(deferoutput=True)
     seencommand = False
 
     outstream = reactor.makeoutputstream()
 
     while True:
         frame = wireprotoframing.readframe(req.bodyfh)
         if not frame:
             break
 
         action, meta = reactor.onframerecv(frame)
 
         if action == 'wantframe':
             # Need more data before we can do anything.
             continue
         elif action == 'runcommand':
             sentoutput = _httpv2runcommand(ui, repo, req, res, authedperm,
                                            reqcommand, reactor, outstream,
                                            meta, issubsequent=seencommand)
 
             if sentoutput:
                 return
 
             seencommand = True
 
         elif action == 'error':
             # TODO define proper error mechanism.
             res.status = b'200 OK'
             res.headers[b'Content-Type'] = b'text/plain'
             res.setbodybytes(meta['message'] + b'\n')
             return
         else:
             raise error.ProgrammingError(
                 'unhandled action from frame processor: %s' % action)
 
     action, meta = reactor.oninputeof()
     if action == 'sendframes':
         # We assume we haven't started sending the response yet. If we're
         # wrong, the response type will raise an exception.
         res.status = b'200 OK'
         res.headers[b'Content-Type'] = FRAMINGTYPE
         res.setbodygen(meta['framegen'])
     elif action == 'noop':
         pass
     else:
         raise error.ProgrammingError('unhandled action from frame processor: %s'
                                      % action)
 
 def _httpv2runcommand(ui, repo, req, res, authedperm, reqcommand, reactor,
                       outstream, command, issubsequent):
     """Dispatch a wire protocol command made from HTTPv2 requests.
 
     The authenticated permission (``authedperm``) along with the original
     command from the URL (``reqcommand``) are passed in.
     """
     # We already validated that the session has permissions to perform the
     # actions in ``authedperm``. In the unified frame protocol, the canonical
     # command to run is expressed in a frame. However, the URL also requested
     # to run a specific command. We need to be careful that the command we
     # run doesn't have permissions requirements greater than what was granted
     # by ``authedperm``.
     #
     # Our rule for this is we only allow one command per HTTP request and
     # that command must match the command in the URL. However, we make
     # an exception for the ``multirequest`` URL. This URL is allowed to
     # execute multiple commands. We double check permissions of each command
     # as it is invoked to ensure there is no privilege escalation.
     # TODO consider allowing multiple commands to regular command URLs
     # iff each command is the same.
 
     proto = httpv2protocolhandler(req, ui, args=command['args'])
 
     if reqcommand == b'multirequest':
         if not wireproto.commandsv2.commandavailable(command['command'], proto):
             # TODO proper error mechanism
             res.status = b'200 OK'
             res.headers[b'Content-Type'] = b'text/plain'
             res.setbodybytes(_('wire protocol command not available: %s') %
                              command['command'])
             return True
 
         # TODO don't use assert here, since it may be elided by -O.
         assert authedperm in (b'ro', b'rw')
         wirecommand = wireproto.commandsv2[command['command']]
         assert wirecommand.permission in ('push', 'pull')
 
         if authedperm == b'ro' and wirecommand.permission != 'pull':
             # TODO proper error mechanism
             res.status = b'403 Forbidden'
             res.headers[b'Content-Type'] = b'text/plain'
             res.setbodybytes(_('insufficient permissions to execute '
                                'command: %s') % command['command'])
             return True
 
         # TODO should we also call checkperm() here? Maybe not if we're going
         # to overhaul that API. The granted scope from the URL check should
         # be good enough.
 
     else:
         # Don't allow multiple commands outside of ``multirequest`` URL.
         if issubsequent:
             # TODO proper error mechanism
             res.status = b'200 OK'
             res.headers[b'Content-Type'] = b'text/plain'
             res.setbodybytes(_('multiple commands cannot be issued to this '
                                'URL'))
             return True
 
         if reqcommand != command['command']:
             # TODO define proper error mechanism
             res.status = b'200 OK'
             res.headers[b'Content-Type'] = b'text/plain'
             res.setbodybytes(_('command in frame must match command in URL'))
             return True
 
     rsp = wireproto.dispatch(repo, proto, command['command'])
 
     res.status = b'200 OK'
     res.headers[b'Content-Type'] = FRAMINGTYPE
 
     if isinstance(rsp, wireprototypes.cborresponse):
         encoded = cbor.dumps(rsp.value, canonical=True)
         action, meta = reactor.oncommandresponseready(outstream,
                                                       command['requestid'],
                                                       encoded)
+    elif isinstance(rsp, wireprototypes.v2streamingresponse):
+        action, meta = reactor.oncommandresponsereadygen(outstream,
+                                                         command['requestid'],
+                                                         rsp.gen)
+    elif isinstance(rsp, wireprototypes.v2errorresponse):
+        action, meta = reactor.oncommanderror(outstream,
+                                              command['requestid'],
+                                              rsp.message,
+                                              rsp.args)
     else:
         action, meta = reactor.onservererror(
             _('unhandled response type from wire proto command'))
 
     if action == 'sendframes':
         res.setbodygen(meta['framegen'])
         return True
     elif action == 'noop':
         return False
     else:
         raise error.ProgrammingError('unhandled event from reactor: %s' %
                                      action)
 
 @zi.implementer(wireprototypes.baseprotocolhandler)
 class httpv2protocolhandler(object):
     def __init__(self, req, ui, args=None):
         self._req = req
         self._ui = ui
         self._args = args
 
     @property
     def name(self):
         return HTTP_WIREPROTO_V2
 
     def getargs(self, args):
         data = {}
         for k, typ in args.items():
             if k == '*':
                 raise NotImplementedError('do not support * args')
             elif k in self._args:
                 # TODO consider validating value types.
                 data[k] = self._args[k]
 
         return data
 
     def getprotocaps(self):
         # Protocol capabilities are currently not implemented for HTTP V2.
         return set()
 
     def getpayload(self):
         raise NotImplementedError
 
     @contextlib.contextmanager
     def mayberedirectstdio(self):
         raise NotImplementedError
 
     def client(self):
         raise NotImplementedError
 
     def addcapabilities(self, repo, caps):
         return caps
 
     def checkperm(self, perm):
         raise NotImplementedError
 
 def httpv2apidescriptor(req, repo):
     proto = httpv2protocolhandler(req, repo.ui)
 
     return _capabilitiesv2(repo, proto)
 
 def _capabilitiesv2(repo, proto):
     """Obtain the set of capabilities for version 2 transports.
 
     These capabilities are distinct from the capabilities for version 1
     transports.
     """
     compression = []
     for engine in wireproto.supportedcompengines(repo.ui, util.SERVERROLE):
         compression.append({
             b'name': engine.wireprotosupport().name,
         })
 
     caps = {
         'commands': {},
         'compression': compression,
         'framingmediatypes': [FRAMINGTYPE],
     }
 
     for command, entry in wireproto.commandsv2.items():
         caps['commands'][command] = {
             'args': entry.args,
             'permissions': [entry.permission],
         }
 
     if streamclone.allowservergeneration(repo):
         caps['rawrepoformats'] = sorted(repo.requirements &
                                         repo.supportedformats)
 
     return proto.addcapabilities(repo, caps)
 
 def wireprotocommand(*args, **kwargs):
     def register(func):
         return wireproto.wireprotocommand(
             *args, transportpolicy=wireproto.POLICY_V2_ONLY, **kwargs)(func)
 
     return register
 
 @wireprotocommand('branchmap', permission='pull')
 def branchmapv2(repo, proto):
     branchmap = {encoding.fromlocal(k): v
                  for k, v in repo.branchmap().iteritems()}
 
     return wireprototypes.cborresponse(branchmap)
 
 @wireprotocommand('capabilities', permission='pull')
 def capabilitiesv2(repo, proto):
     caps = _capabilitiesv2(repo, proto)
 
     return wireprototypes.cborresponse(caps)
 
 @wireprotocommand('heads',
                   args={
                       'publiconly': False,
                   },
                   permission='pull')
 def headsv2(repo, proto, publiconly=False):
     if publiconly:
         repo = repo.filtered('immutable')
 
     return wireprototypes.cborresponse(repo.heads())
 
 @wireprotocommand('known',
                   args={
                       'nodes': [b'deadbeef'],
                   },
                   permission='pull')
 def knownv2(repo, proto, nodes=None):
     nodes = nodes or []
     result = b''.join(b'1' if n else b'0' for n in repo.known(nodes))
     return wireprototypes.cborresponse(result)
 
 @wireprotocommand('listkeys',
                   args={
                       'namespace': b'ns',
                   },
                   permission='pull')
 def listkeysv2(repo, proto, namespace=None):
     keys = repo.listkeys(encoding.tolocal(namespace))
     keys = {encoding.fromlocal(k): encoding.fromlocal(v)
             for k, v in keys.iteritems()}
 
     return wireprototypes.cborresponse(keys)
 
 @wireprotocommand('lookup',
                   args={
                       'key': b'foo',
                   },
                   permission='pull')
 def lookupv2(repo, proto, key):
     key = encoding.tolocal(key)
 
     # TODO handle exception.
     node = repo.lookup(key)
 
     return wireprototypes.cborresponse(node)
 
 @wireprotocommand('pushkey',
                   args={
                       'namespace': b'ns',
                       'key': b'key',
                       'old': b'old',
                       'new': b'new',
                   },
                   permission='push')
 def pushkeyv2(repo, proto, namespace, key, old, new):
     # TODO handle ui output redirection
     r = repo.pushkey(encoding.tolocal(namespace),
                      encoding.tolocal(key),
                      encoding.tolocal(old),
                      encoding.tolocal(new))
 
     return wireprototypes.cborresponse(r)