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