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 = None  # Will be set on connect().
  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         if self.message_thread.daemon is not None:
  73             raise RuntimeError(
  74                 "PAPI socket transport connect: You need to disconnect first.")
  75         self.message_thread.daemon = threading.Thread(
  76             target=self.msg_thread_func)
  77
  78         # Create a UDS socket
  79         self.socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
  80         self.socket.settimeout(self.read_timeout)
  81
  82         # Connect the socket to the port where the server is listening
  83         try:
  84             self.socket.connect(self.server_address)
  85         except socket.error as msg:
  86             logging.error("{} on socket {}".format(msg, self.server_address))
  87             raise
  88
  89         self.connected = True
  90         # Initialise sockclnt_create
  91         sockclnt_create = self.parent.messages['sockclnt_create']
  92         sockclnt_create_reply = self.parent.messages['sockclnt_create_reply']
  93
  94         args = {'_vl_msg_id': 15,
  95                 'name': name,
  96                 'context': 124}
  97         b = sockclnt_create.pack(args)
  98         self.write(b)
  99         msg = self._read()
 100         hdr, length = self.parent.header.unpack(msg, 0)
 101         if hdr.msgid != 16:
 102             raise VppTransportSocketIOError('Invalid reply message')
 103
 104         r, length = sockclnt_create_reply.unpack(msg)
 105         self.socket_index = r.index
 106         for m in r.message_table:
 107             n = m.name.rstrip(b'\x00\x13')
 108             self.message_table[n] = m.index
 109
 110         self.message_thread.daemon = True
 111         self.message_thread.start()
 112
 113         return 0
 114
 115     def disconnect(self):
 116         # TODO: Should we detect if user forgot to connect first?
 117         rv = 0
 118         try:  # Might fail, if VPP closes socket before packet makes it out
 119             rv = self.parent.api.sockclnt_delete(index=self.socket_index)
 120         except IOError:
 121             pass
 122         self.connected = False
 123         self.socket.close()
 124         self.sque.put(True)  # Terminate listening thread
 125         self.message_thread.join()
 126         # Allow additional connect() calls.
 127         self.message_thread = None
 128         return rv
 129
 130     def suspend(self):
 131         pass
 132
 133     def resume(self):
 134         pass
 135
 136     def callback(self):
 137         raise NotImplementedError
 138
 139     def get_callback(self, do_async):
 140         return self.callback
 141
 142     def get_msg_index(self, name):
 143         try:
 144             return self.message_table[name]
 145         except KeyError:
 146             return 0
 147
 148     def msg_table_max_index(self):
 149         return len(self.message_table)
 150
 151     def write(self, buf):
 152         """Send a binary-packed message to VPP."""
 153         if not self.connected:
 154             raise VppTransportSocketIOError(1, 'Not connected')
 155
 156         # Send header
 157         header = self.header.pack(0, len(buf), 0)
 158         n = self.socket.send(header)
 159         n = self.socket.send(buf)
 160
 161     def _read(self):
 162         hdr = self.socket.recv(16)
 163         if not hdr:
 164             return
 165         (_, l, _) = self.header.unpack(hdr) # If at head of message
 166
 167         # Read rest of message
 168         msg = self.socket.recv(l)
 169         if l > len(msg):
 170             nbytes = len(msg)
 171             buf = bytearray(l)
 172             view = memoryview(buf)
 173             view[:nbytes] = msg
 174             view = view[nbytes:]
 175             left = l - nbytes
 176             while left:
 177                 nbytes = self.socket.recv_into(view, left)
 178                 view = view[nbytes:]
 179                 left -= nbytes
 180             return buf
 181         if l == len(msg):
 182             return msg
 183         raise VPPTransportSocketIOError(1, 'Unknown socket read error')
 184
 185     def read(self):
 186         if not self.connected:
 187             raise VppTransportSocketIOError(1, 'Not connected')
 188         try:
 189             return self.q.get(True, self.read_timeout)
 190         except queue.Empty:
 191             return None