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/ dulwich |
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# server.py -- Implementation of the server side git protocols
# Copryight (C) 2008 John Carr <john.carr@unrouted.co.uk>
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; version 2
# or (at your option) any later version of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
# MA 02110-1301, USA.
"""Git smart network protocol server implementation."""
import collections
import SocketServer
import tempfile
from dulwich.errors import (
GitProtocolError,
)
from dulwich.objects import (
hex_to_sha,
)
from dulwich.protocol import (
Protocol,
ProtocolFile,
TCP_GIT_PORT,
extract_capabilities,
extract_want_line_capabilities,
SINGLE_ACK,
MULTI_ACK,
ack_type,
)
from dulwich.repo import (
Repo,
)
from dulwich.pack import (
write_pack_data,
)
class Backend(object):
def get_refs(self):
"""
Get all the refs in the repository
:return: dict of name -> sha
"""
raise NotImplementedError
def apply_pack(self, refs, read):
""" Import a set of changes into a repository and update the refs
:param refs: list of tuple(name, sha)
:param read: callback to read from the incoming pack
"""
raise NotImplementedError
def fetch_objects(self, determine_wants, graph_walker, progress):
"""
Yield the objects required for a list of commits.
:param progress: is a callback to send progress messages to the client
"""
raise NotImplementedError
class GitBackend(Backend):
def __init__(self, repo=None):
if repo is None:
repo = Repo(tmpfile.mkdtemp())
self.repo = repo
self.object_store = self.repo.object_store
self.fetch_objects = self.repo.fetch_objects
self.get_refs = self.repo.get_refs
def apply_pack(self, refs, read):
f, commit = self.repo.object_store.add_thin_pack()
try:
f.write(read())
finally:
commit()
for oldsha, sha, ref in refs:
if ref == "0" * 40:
del self.repo.refs[ref]
else:
self.repo.refs[ref] = sha
print "pack applied"
class Handler(object):
"""Smart protocol command handler base class."""
def __init__(self, backend, read, write):
self.backend = backend
self.proto = Protocol(read, write)
def capabilities(self):
return " ".join(self.default_capabilities())
class UploadPackHandler(Handler):
"""Protocol handler for uploading a pack to the server."""
def __init__(self, backend, read, write):
Handler.__init__(self, backend, read, write)
self._client_capabilities = None
self._graph_walker = None
def default_capabilities(self):
return ("multi_ack", "side-band-64k", "thin-pack", "ofs-delta")
def set_client_capabilities(self, caps):
my_caps = self.default_capabilities()
for cap in caps:
if '_ack' in cap and cap not in my_caps:
raise GitProtocolError('Client asked for capability %s that '
'was not advertised.' % cap)
self._client_capabilities = caps
def get_client_capabilities(self):
return self._client_capabilities
client_capabilities = property(get_client_capabilities,
set_client_capabilities)
def handle(self):
def determine_wants(heads):
keys = heads.keys()
values = set(heads.itervalues())
if keys:
self.proto.write_pkt_line("%s %s\x00%s\n" % ( heads[keys[0]], keys[0], self.capabilities()))
for k in keys[1:]:
self.proto.write_pkt_line("%s %s\n" % (heads[k], k))
# i'm done..
self.proto.write("0000")
# Now client will either send "0000", meaning that it doesnt want to pull.
# or it will start sending want want want commands
want = self.proto.read_pkt_line()
if want == None:
return []
want, self.client_capabilities = extract_want_line_capabilities(want)
graph_walker.set_ack_type(ack_type(self.client_capabilities))
want_revs = []
while want and want[:4] == 'want':
sha = want[5:45]
try:
hex_to_sha(sha)
except (TypeError, AssertionError), e:
raise GitProtocolError(e)
if sha not in values:
raise GitProtocolError(
'Client wants invalid object %s' % sha)
want_revs.append(sha)
want = self.proto.read_pkt_line()
graph_walker.set_wants(want_revs)
return want_revs
progress = lambda x: self.proto.write_sideband(2, x)
write = lambda x: self.proto.write_sideband(1, x)
graph_walker = ProtocolGraphWalker(self.backend.object_store, self.proto)
objects_iter = self.backend.fetch_objects(determine_wants, graph_walker, progress)
# Do they want any objects?
if len(objects_iter) == 0:
return
progress("dul-daemon says what\n")
progress("counting objects: %d, done.\n" % len(objects_iter))
write_pack_data(ProtocolFile(None, write), objects_iter,
len(objects_iter))
progress("how was that, then?\n")
# we are done
self.proto.write("0000")
class ProtocolGraphWalker(object):
"""A graph walker that knows the git protocol.
As a graph walker, this class implements ack(), next(), and reset(). It also
contains some base methods for interacting with the wire and walking the
commit tree.
The work of determining which acks to send is passed on to the
implementation instance stored in _impl. The reason for this is that we do
not know at object creation time what ack level the protocol requires. A
call to set_ack_level() is required to set up the implementation, before any
calls to next() or ack() are made.
"""
def __init__(self, object_store, proto):
self.store = object_store
self.proto = proto
self._wants = []
self._cached = False
self._cache = []
self._cache_index = 0
self._impl = None
def ack(self, have_ref):
return self._impl.ack(have_ref)
def reset(self):
self._cached = True
self._cache_index = 0
def next(self):
if not self._cached:
return self._impl.next()
self._cache_index += 1
if self._cache_index > len(self._cache):
return None
return self._cache[self._cache_index]
def read_proto_line(self):
"""Read a line from the wire.
:return: a tuple having one of the following forms:
('have', obj_id)
('done', None)
(None, None) (for a flush-pkt)
"""
line = self.proto.read_pkt_line()
if not line:
return (None, None)
fields = line.rstrip('\n').split(' ', 1)
if len(fields) == 1 and fields[0] == 'done':
return ('done', None)
if len(fields) == 2 and fields[0] == 'have':
try:
hex_to_sha(fields[1])
return fields
except (TypeError, AssertionError), e:
raise GitProtocolError(e)
raise GitProtocolError('Received invalid line from client:\n%s' % line)
def send_ack(self, sha, ack_type=''):
if ack_type:
ack_type = ' %s' % ack_type
self.proto.write_pkt_line('ACK %s%s\n' % (sha, ack_type))
def send_nak(self):
self.proto.write_pkt_line('NAK\n')
def set_wants(self, wants):
self._wants = wants
def _is_satisfied(self, haves, want, earliest):
"""Check whether a want is satisfied by a set of haves.
A want, typically a branch tip, is "satisfied" only if there exists a
path back from that want to one of the haves.
:param haves: A set of commits we know the client has.
:param want: The want to check satisfaction for.
:param earliest: A timestamp beyond which the search for haves will be
terminated, presumably because we're searching too far down the
wrong branch.
"""
o = self.store[want]
pending = collections.deque([o])
while pending:
commit = pending.popleft()
if commit.id in haves:
return True
if not getattr(commit, 'get_parents', None):
# non-commit wants are assumed to be satisfied
continue
for parent in commit.get_parents():
parent_obj = self.store[parent]
# TODO: handle parents with later commit times than children
if parent_obj.commit_time >= earliest:
pending.append(parent_obj)
return False
def all_wants_satisfied(self, haves):
"""Check whether all the current wants are satisfied by a set of haves.
:param haves: A set of commits we know the client has.
:note: Wants are specified with set_wants rather than passed in since
in the current interface they are determined outside this class.
"""
haves = set(haves)
earliest = min([self.store[h].commit_time for h in haves])
for want in self._wants:
if not self._is_satisfied(haves, want, earliest):
return False
return True
def set_ack_type(self, ack_type):
impl_classes = {
MULTI_ACK: MultiAckGraphWalkerImpl,
SINGLE_ACK: SingleAckGraphWalkerImpl,
}
self._impl = impl_classes[ack_type](self)
class SingleAckGraphWalkerImpl(object):
"""Graph walker implementation that speaks the single-ack protocol."""
def __init__(self, walker):
self.walker = walker
self._sent_ack = False
def ack(self, have_ref):
if not self._sent_ack:
self.walker.send_ack(have_ref)
self._sent_ack = True
def next(self):
command, sha = self.walker.read_proto_line()
if command in (None, 'done'):
if not self._sent_ack:
self.walker.send_nak()
return None
elif command == 'have':
return sha
class MultiAckGraphWalkerImpl(object):
"""Graph walker implementation that speaks the multi-ack protocol."""
def __init__(self, walker):
self.walker = walker
self._found_base = False
self._common = []
def ack(self, have_ref):
self._common.append(have_ref)
if not self._found_base:
self.walker.send_ack(have_ref, 'continue')
if self.walker.all_wants_satisfied(self._common):
self._found_base = True
# else we blind ack within next
def next(self):
command, sha = self.walker.read_proto_line()
if command is None:
self.walker.send_nak()
return None
elif command == 'done':
# don't nak unless no common commits were found, even if not
# everything is satisfied
if self._common:
self.walker.send_ack(self._common[-1])
else:
self.walker.send_nak()
return None
elif command == 'have':
if self._found_base:
# blind ack
self.walker.send_ack(sha, 'continue')
return sha
class ReceivePackHandler(Handler):
"""Protocol handler for downloading a pack to the client."""
def default_capabilities(self):
return ("report-status", "delete-refs")
def handle(self):
refs = self.backend.get_refs().items()
if refs:
self.proto.write_pkt_line("%s %s\x00%s\n" % (refs[0][1], refs[0][0], self.capabilities()))
for i in range(1, len(refs)):
ref = refs[i]
self.proto.write_pkt_line("%s %s\n" % (ref[1], ref[0]))
else:
self.proto.write_pkt_line("0000000000000000000000000000000000000000 capabilities^{} %s" % self.capabilities())
self.proto.write("0000")
client_refs = []
ref = self.proto.read_pkt_line()
# if ref is none then client doesnt want to send us anything..
if ref is None:
return
ref, client_capabilities = extract_capabilities(ref)
# client will now send us a list of (oldsha, newsha, ref)
while ref:
client_refs.append(ref.split())
ref = self.proto.read_pkt_line()
# backend can now deal with this refs and read a pack using self.read
self.backend.apply_pack(client_refs, self.proto.read)
# when we have read all the pack from the client, it assumes
# everything worked OK.
# there is NO ack from the server before it reports victory.
class TCPGitRequestHandler(SocketServer.StreamRequestHandler):
def handle(self):
proto = Protocol(self.rfile.read, self.wfile.write)
command, args = proto.read_cmd()
# switch case to handle the specific git command
if command == 'git-upload-pack':
cls = UploadPackHandler
elif command == 'git-receive-pack':
cls = ReceivePackHandler
else:
return
h = cls(self.server.backend, self.rfile.read, self.wfile.write)
h.handle()
class TCPGitServer(SocketServer.TCPServer):
allow_reuse_address = True
serve = SocketServer.TCPServer.serve_forever
def __init__(self, backend, listen_addr, port=TCP_GIT_PORT):
self.backend = backend
SocketServer.TCPServer.__init__(self, (listen_addr, port), TCPGitRequestHandler)
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