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Diffstat (limited to 'sugar/p2p/MostlyReliablePipe.py')
| -rw-r--r-- | sugar/p2p/MostlyReliablePipe.py | 319 |
1 files changed, 0 insertions, 319 deletions
diff --git a/sugar/p2p/MostlyReliablePipe.py b/sugar/p2p/MostlyReliablePipe.py deleted file mode 100644 index f85a815..0000000 --- a/sugar/p2p/MostlyReliablePipe.py +++ /dev/null @@ -1,319 +0,0 @@ -import socket -import time -import sha -import struct -import StringIO -import binascii - -import pygtk -pygtk.require('2.0') -import gtk, gobject - - -_MTU = 482 -_HEADER_LEN = 30 -_MAGIC = 0xbaea4304 -_TTL = 120 # 2 minutes - -def _stringify_sha(sha): - print_sha = "" - for char in sha: - print_sha = print_sha + binascii.b2a_hex(char) - return print_sha - -def _sha_data(data): - sha_hash = sha.new() - sha_hash.update(data) - return sha_hash.digest() - -class MessageSegment(object): - # 4: magic (0xbaea4304) - # 2: segment number - # 2: total segments - # 2: message sequence number - #20: total data sha1 - _HEADER_TEMPLATE = "! IHHH20s" - - def _new_from_parts(self, msg_seq_num, segno, total_segs, data, master_sha): - """Construct a new message segment from individual attributes.""" - if not data: - raise ValueError("Must have valid data.") - if segno > 65535: - raise ValueError("Segment number cannot be more than 65535.") - if segno < 1: - raise ValueError("Segment number must be greater than zero.") - if total_segs > 65535: - raise ValueError("Message cannot have more than 65535 segments.") - if total_segs < 1: - raise ValueError("Message must have at least one segment.") - if msg_seq_num < 1: - raise ValueError("Message sequence number must be greater than 0.") - self._stime = time.time() - self._data = data - self._data_len = len(data) - self._master_sha = master_sha - self._segno = segno - self._total_segs = total_segs - self._msg_seq_num = msg_seq_num - self._addr = None - - # Make the header - self._header = struct.pack(self._HEADER_TEMPLATE, _MAGIC, self._segno, - self._total_segs, self._msg_seq_num, self._master_sha) - - def _new_from_data(self, addr, data): - """Verify and construct a new message segment from network data.""" - if len(data) < _HEADER_LEN + 1: - raise ValueError("Message is less then minimum required length") - stream = StringIO.StringIO(data) - self._stime = None - self._addr = addr - - # Determine and verify the length of included data - stream.seek(0, 2) - header_size = struct.calcsize(self._HEADER_TEMPLATE) - self._data_len = stream.tell() - header_size - if self._data_len < 1: - raise ValueError("Message must have some data.") - if self._data_len > _MTU: - raise ValueError("Data length must not be larger than the MTU (%s)." % _MTU) - stream.seek(0) - - # Read the header attributes - (magic, segno, total_segs, msg_seq_num, master_sha) = struct.unpack(self._HEADER_TEMPLATE, - stream.read(header_size)) - - # Sanity checks on the message attributes - if magic != _MAGIC: - raise ValueError("Message does not have the correct magic.") - if segno < 1: - raise ValueError("Segment number must be greater than 0.") - if segno > total_segs: - raise ValueError("Segment number cannot be larger than message segment total.") - if total_segs < 1: - raise ValueError("Message must have at least one segment.") - if msg_seq_num < 1: - raise ValueError("Message sequence number must be greater than 0.") - - self._segno = segno - self._total_segs = total_segs - self._msg_seq_num = msg_seq_num - self._master_sha = master_sha - - # Reconstruct the data - self._data = struct.unpack("! %ds" % self._data_len, stream.read(self._data_len))[0] - - def new_from_parts(msg_seq_num, segno, total_segs, data, master_sha): - """Static constructor for creation from individual attributes.""" - segment = MessageSegment() - segment._new_from_parts(msg_seq_num, segno, total_segs, data, master_sha) - return segment - new_from_parts = staticmethod(new_from_parts) - - def new_from_data(addr, data): - """Static constructor for creation from a packed data stream.""" - segment = MessageSegment() - segment._new_from_data(addr, data) - return segment - new_from_data = staticmethod(new_from_data) - - def stime(self): - return self._stime - - def addr(self): - return self._addr - - def segment_number(self): - return self._segno - - def total_segments(self): - return self._total_segs - - def message_sequence_number(self): - return self._msg_seq_num - - def data(self): - return self._data - - def master_sha(self): - return self._master_sha - - def segment(self): - """Return a correctly formatted message that can be immediately sent.""" - return self._header + self._data - -class MostlyReliablePipe(object): - """Implement Mostly-Reliable UDP. We don't actually care about guaranteeing - delivery or receipt, just a better effort than no effort at all.""" - - def __init__(self, local_addr, remote_addr, port, data_cb, user_data=None): - self._local_addr = local_addr - self._remote_addr = remote_addr - self._port = port - self._data_cb = data_cb - self._user_data = user_data - self._started = False - self._worker = 0 - self._seq_counter = 0 - - self._outgoing = [] - self._sent = [] - - self._incoming = {} # (message sha, # of segments) -> [segment1, segment2, ...] - - self._setup_listener() - self._setup_sender() - - def _setup_sender(self): - """Setup the send socket for multicast.""" - self._send_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) - # Make the socket multicast-aware, and set TTL. - self._send_sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 20) # Change TTL (=20) to suit - - def _setup_listener(self): - """Set up the listener socket for multicast traffic.""" - # Listener socket - self._listen_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) - - # Set some options to make it multicast-friendly - self._listen_sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) - self._listen_sock.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_TTL, 20) - self._listen_sock.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_LOOP, 1) - - def start(self): - """Let the listener socket start listening for network data.""" - # Set some more multicast options - self._listen_sock.bind((self._local_addr, self._port)) # Bind to all interfaces - self._listen_sock.settimeout(2) - intf = socket.gethostbyname(socket.gethostname()) - self._listen_sock.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_IF, - socket.inet_aton(intf) + socket.inet_aton('0.0.0.0')) - self._listen_sock.setsockopt(socket.SOL_IP, socket.IP_ADD_MEMBERSHIP, - socket.inet_aton(self._remote_addr) + socket.inet_aton('0.0.0.0')) - - # Watch the listener socket for data - gobject.io_add_watch(self._listen_sock, gobject.IO_IN, self._handle_incoming_data) - gobject.timeout_add(120000, self._segment_ttl_worker) - - self._started = True - - def _segment_ttl_worker(self): - """Cull already-sent message segments that are past their TTL.""" - now = time.time() - for segment in self._sent[:]: - if segment.stime() < now - _MSG_TTL: - self._sent.remove(segment) - return True - - def _dispatch_message(self, addr, message): - """Send complete message data to the owner's data callback.""" - self._data_cb(addr, message, self._user_data) - - def _process_incoming(self, segment): - """Handle a new message segment. First checks if there is only one - segment to the message, and if the checksum from the header matches - that computed from the data, dispatches it. Otherwise, it adds the - new segment to the list of other segments for that message, and - checks to see if the message is complete. If all segments are present, - the message is reassembled and dispatched.""" - - string_sha = _stringify_sha(segment.master_sha()) - nsegs = segment.total_segments() - addr = segment.addr() - segno = segment.segment_number() - - # Short-circuit single-segment messages - if segno == 1 and nsegs == 1: - # Ensure the header's master sha actually equals the data's sha - if string_sha == _stringify_sha(_sha_data(segment.data())): - self._dispatch_message(addr, segment.data()) - return - - # Otherwise, track the new segment - msg_seq_num = segment.message_sequence_number() - msg_key = (addr[0], msg_seq_num, string_sha, nsegs) - if not self._incoming.has_key(msg_key): - self._incoming[msg_key] = {} - - # Look for a dupe, and if so, drop the new segment - if self._incoming[msg_key].has_key(segno): - return - self._incoming[msg_key][segno] = segment - - # Dispatch the message if all segments are present and the sha is correct - if len(self._incoming[msg_key]) == nsegs: - all_data = '' - for i in range(1, nsegs + 1): - all_data = all_data + self._incoming[msg_key][i].data() - if string_sha == _stringify_sha(_sha_data(all_data)): - self._dispatch_message(addr, all_data) - del self._incoming[msg_key] - - def _handle_incoming_data(self, source, condition): - """Handle incoming network data by making a message segment out of it - sending it off to the processing function.""" - if not (condition & gobject.IO_IN): - return True - msg = {} - data, addr = source.recvfrom(_MTU + _HEADER_LEN) - try: - segment = MessageSegment.new_from_data(addr, data) - self._process_incoming(segment) - except ValueError, exc: - pass - return True - - def send(self, data): - """Break data up into chunks and queue for later transmission.""" - if not self._started: - raise Exception("Can't send anything until started!") - - self._seq_counter = self._seq_counter + 1 - if self._seq_counter > 65535: - self._seq_counter = 1 - - # Pack the data into network byte order - template = "! %ds" % len(data) - data = struct.pack(template, data) - master_sha = _sha_data(data) - - # Split up the data into segments - left = length = len(data) - nmessages = length / _MTU - if length % _MTU > 0: - nmessages = nmessages + 1 - msg_num = 1 - while left > 0: - msg = MessageSegment.new_from_parts(self._seq_counter, msg_num, - nmessages, data[:_MTU], master_sha) - self._outgoing.append(msg) - msg_num = msg_num + 1 - data = data[_MTU:] - left = left - _MTU - if len(self._outgoing) > 0 and self._worker == 0: - self._worker = gobject.idle_add(self._send_worker) - - def _send_worker(self): - """Send all queued segments that have yet to be transmitted.""" - self._worker = 0 - for segment in self._outgoing: - data = segment.segment() - self._send_sock.sendto(data, (self._remote_addr, self._port)) - self._sent = self._outgoing - self._outgoing = [] - return False - - -def got_data(addr, data, user_data=None): - print "Data (%s): %s" % (addr, data) - -def main(): - pipe = MostlyReliablePipe('', '224.0.0.222', 2293, got_data) - pipe.start() - pipe.send('The quick brown fox jumps over the lazy dog') - gtk.main() - - -if __name__ == "__main__": - main() - |