Server side git protocols

dulwich/server.py

@@ -0,0 +1,195 @@
+# 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
+# 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.
+
+import SocketServer
+# import dulwich as git
+
+
+class Backend(object):
+
+    def __init__(self):
+        pass
+
+    def get_refs(self):
+        raise NotImplementedError
+
+    def has_revision(self):
+        raise NotImplementedError
+
+    def apply_pack(self, refs, read):
+        raise NotImplementedError
+
+    def generate_pack(self, want, have, write, progress):
+        raise NotImplementedError
+
+
+class Handler(object):
+
+    def __init__(self, backend, read, write):
+        self.backend = backend
+        self.read = read
+        self.write = write
+
+    def read_pkt_line(self):
+        """
+        reads a 'git line' of info from the stream
+        """
+        size = int(self.read(4), 16)
+        if size == 0:
+            return None
+        return self.read(size-4)
+
+    def write_pkt_line(self, line):
+        self.write("%04x%s" % (len(line)+4, line))
+
+    def write_sideband(self, channel, blob):
+        # a pktline can be a max of 65535. a sideband line can therefore be
+        # 65535-5 = 65530
+        # WTF: Why have the len in ASCII, but the channel in binary.
+        while blob:
+            self.write_pkt_line("%s%s" % (chr(channel), blob[:65530]))
+            blob = blob[65530:]
+
+    def handle(self):
+        raise NotImplementedError
+
+
+class UploadPackHandler(Handler):
+
+    def handle(self):
+        refs = self.backend.get_refs()
+
+        self.write_pkt_line("%s %s\x00multi_ack side-band-64k thin-pack ofs-delta\0x0a" % (refs[0][1], refs[0][0]))
+        for i in range(1, len(refs)-1):
+            ref = refs[i]
+            self.write_pkt_line("%s %s\0x0a" % (ref[1], ref[0]))
+
+        # i'm done...
+        self.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.read_pkt_line()
+        if want == None:
+            return
+       
+        # Keep reading the list of demands until we hit another "0000" 
+        want_revs = []
+        while want and want[:4] == 'want':
+            want_rev = want[5:]
+            # FIXME: This check probably isnt needed?
+            if self.backend.has_revision(want_rev):
+               want_revs.append(want_rev)
+            want = self.read_pkt_line()
+        
+        # Client will now tell us which commits it already has - if we have them we ACK them
+        # this allows client to stop looking at that commits parents (main reason why git pull is fast)
+        last_sha = None
+        have_revs = []
+        have = self.read_pkt_line()
+        while have and have[:4] == 'have':
+            have_ref = have[6:40]
+            if self.backend.has_revision(hav_rev):
+                self.write_pkt_line("ACK %s continue\n" % sha)
+                last_sha = sha
+                have_revs.append(rev_id)
+            have = self.read_pkt_line()
+
+        # At some point client will stop sending commits and will tell us it is done
+        assert(have[:4] == "done")
+
+        # Oddness: Git seems to resend the last ACK, without the "continue" statement
+        if last_sha:
+            self.write_pkt_line("ACK %s\n" % last_sha)
+
+        # The exchange finishes with a NAK
+        self.write_pkt_line("NAK\n")
+      
+        #if True: # False: #self.no_progress == False:
+        #    self.write_sideband(2, "Bazaar is preparing your pack, plz hold.\n")
+
+        #    for x in range(1,200):
+        #        self.write_sideband(2, "Counting objects: %d\x0d" % x*2)
+        #    self.write_sideband(2, "Counting objects: 200, done.\n")
+
+        #    for x in range(1,100):
+        #        self.write_sideband(2, "Compressiong objects: %d (%d/%d)\x0d" % (x, x*2, 200))
+        #    self.write_sideband(2, "Compressing objects: 100% (200/200), done.\n")
+
+        self.backend.generate_pack(want, need, self.write)
+
+
+class ReceivePackHandler(Handler):
+
+    def handle(self):
+        refs = self.backend.get_refs()
+
+        self.write_pkt_line("%s %s\x00multi_ack side-band-64k thin-pack ofs-delta\0x0a" % (refs[0][1], refs[0][0]))
+        for i in range(1, len(refs)-1):
+            ref = refs[i]
+            self.write_pkt_line("%s %s\0x0a" % (ref[1], ref[0]))
+
+        self.write("0000")
+
+        client_refs = []
+        ref = self.read_pkt_line()
+        while ref:
+            client_refs.append(ref.split())
+            ref = self.read_pkt_line()
+
+        self.backend.apply_pack(client_refs, self.read)
+
+
+class TCPGitRequestHandler(SocketServer.StreamRequestHandler, Handler):
+
+    def __init__(self, request, client_address, server):
+        SocketServer.StreamRequestHandler.__init__(self, request, client_address, server)
+        Handler.__init__(self, server.backend, self.rfile.read, self.wfile.write)
+
+    def handle(self):
+        request = self.read_pkt_line()
+
+        # up until the space is the command to run, everything after is parameters
+        splice_point = request.find(' ')
+        command, params = request[:splice_point], request[splice_point+1:]
+
+        # params are null seperated
+        params = params.split(chr(0))
+
+        # 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.backend, self.read, self.write)
+        h.handle()
+
+
+class TCPGitServer(SocketServer.TCPServer):
+
+    allow_reuse_address = True
+    serve = SocketServer.TCPServer.serve_forever
+
+    def __init__(self, backend, addr):
+        self.backend = backend
+        SocketServer.TCPServer.__init__(self, addr, TCPGitRequestHandler)
+
+