src/vpp-api/python/vpp_papi/vpp_transport_socket.py

   1 #
   2 # VPP Unix Domain Socket Transport.
   3 #
   4 import socket
   5 import struct
   6 import threading
   7 import select
   8 import multiprocessing
   9 try:
  10     import queue as queue
  11 except ImportError:
  12     import Queue as queue
  13 import logging
  14
  15
  16 class VppTransportSocketIOError(IOError):
  17     pass
  18
  19
  20 class VppTransport(object):
  21     VppTransportSocketIOError = VppTransportSocketIOError
  22
  23     def __init__(self, parent, read_timeout, server_address):
  24         self.connected = False
  25         self.read_timeout = read_timeout if read_timeout > 0 else 1
  26         self.parent = parent
  27         self.server_address = server_address
  28         self.header = struct.Struct('>QII')
  29         self.message_table = {}
  30         self.sque = multiprocessing.Queue()
  31         self.q = multiprocessing.Queue()
  32         self.message_thread = threading.Thread(target=self.msg_thread_func)
  33
  34     def msg_thread_func(self):
  35         while True:
  36             try:
  37                 rlist, _, _ = select.select([self.socket,
  38                                              self.sque._reader], [], [])
  39             except socket.error:
  40                 # Terminate thread
  41                 logging.error('select failed')
  42                 self.q.put(None)
  43                 return
  44
  45             for r in rlist:
  46                 if r == self.sque._reader:
  47                     # Terminate
  48                     self.q.put(None)
  49                     return
  50
  51                 elif r == self.socket:
  52                     try:
  53                         msg = self._read()
  54                         if not msg:
  55                             self.q.put(None)
  56                             return
  57                     except socket.error:
  58                         self.q.put(None)
  59                         return
  60                     # Put either to local queue or if context == 0
  61                     # callback queue
  62                     if self.parent.has_context(msg):
  63                         self.q.put(msg)
  64                     else:
  65                         self.parent.msg_handler_async(msg)
  66                 else:
  67                     raise VppTransportSocketIOError(
  68                         2, 'Unknown response from select')
  69
  70     def connect(self, name, pfx, msg_handler, rx_qlen):
  71
  72         # Create a UDS socket
  73         self.socket = socket.socket(socket.AF_UNIX, socket.SOCK_SEQPACKET)
  74         self.socket.settimeout(self.read_timeout)
  75
  76         # Connect the socket to the port where the server is listening
  77         try:
  78             self.socket.connect(self.server_address)
  79         except socket.error as msg:
  80             logging.error("{} on socket {}".format(msg, self.server_address))
  81             raise
  82
  83         self.connected = True
  84         # Initialise sockclnt_create
  85         sockclnt_create = self.parent.messages['sockclnt_create']
  86         sockclnt_create_reply = self.parent.messages['sockclnt_create_reply']
  87
  88         args = {'_vl_msg_id': 15,
  89                 'name': name,
  90                 'context': 124}
  91         b = sockclnt_create.pack(args)
  92         self.write(b)
  93         msg = self._read()
  94         hdr, length = self.parent.header.unpack(msg, 0)
  95         if hdr.msgid != 16:
  96             raise VppTransportSocketIOError('Invalid reply message')
  97
  98         r, length = sockclnt_create_reply.unpack(msg)
  99         self.socket_index = r.index
 100         for m in r.message_table:
 101             n = m.name.rstrip(b'\x00\x13')
 102             self.message_table[n] = m.index
 103
 104         self.message_thread.daemon = True
 105         self.message_thread.start()
 106
 107         return 0
 108
 109     def disconnect(self):
 110         rv = 0
 111         try:  # Might fail, if VPP closes socket before packet makes it out
 112             rv = self.parent.api.sockclnt_delete(index=self.socket_index)
 113         except IOError:
 114             pass
 115         self.connected = False
 116         self.socket.close()
 117         self.sque.put(True)  # Terminate listening thread
 118         self.message_thread.join()
 119         return rv
 120
 121     def suspend(self):
 122         pass
 123
 124     def resume(self):
 125         pass
 126
 127     def callback(self):
 128         raise NotImplementedError
 129
 130     def get_callback(self, do_async):
 131         return self.callback
 132
 133     def get_msg_index(self, name):
 134         try:
 135             return self.message_table[name]
 136         except KeyError:
 137             return 0
 138
 139     def msg_table_max_index(self):
 140         return len(self.message_table)
 141
 142     def write(self, buf):
 143         """Send a binary-packed message to VPP."""
 144         if not self.connected:
 145             raise VppTransportSocketIOError(1, 'Not connected')
 146
 147         # Send header
 148         header = self.header.pack(0, len(buf), 0)
 149         n = self.socket.send(header)
 150         n = self.socket.send(buf)
 151
 152     def _read(self):
 153         # Header and message
 154         try:
 155             msg = self.socket.recv(4096)
 156             if len(msg) == 0:
 157                 return None
 158         except socket.error as message:
 159             logging.error(message)
 160             raise
 161
 162         (_, l, _) = self.header.unpack(msg[:16])
 163
 164         if l > len(msg):
 165             buf = bytearray(l + 16)
 166             view = memoryview(buf)
 167             view[:4096] = msg
 168             view = view[4096:]
 169             # Read rest of message
 170             remaining_bytes = l - 4096 + 16
 171             while remaining_bytes > 0:
 172                 bytes_to_read = (remaining_bytes if remaining_bytes
 173                                  <= 4096 else 4096)
 174                 nbytes = self.socket.recv_into(view, bytes_to_read)
 175                 if nbytes == 0:
 176                     logging.error('recv failed')
 177                     break
 178                 view = view[nbytes:]
 179                 remaining_bytes -= nbytes
 180         else:
 181             buf = msg
 182         return buf[16:]
 183
 184     def read(self):
 185         if not self.connected:
 186             raise VppTransportSocketIOError(1, 'Not connected')
 187         try:
 188             return self.q.get(True, self.read_timeout)
 189         except queue.Empty:
 190             return None