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|
#
# VPP Unix Domain Socket Transport.
#
import socket
import struct
import threading
import select
import multiprocessing
import logging
class VppTransport:
def __init__(self, parent, read_timeout, server_address):
self.connected = False
self.read_timeout = read_timeout if read_timeout > 0 else 1
self.parent = parent
self.server_address = server_address
self.header = struct.Struct('>QII')
self.message_table = {}
self.sque = multiprocessing.Queue()
self.q = multiprocessing.Queue()
self.message_thread = threading.Thread(target=self.msg_thread_func)
def msg_thread_func(self):
while True:
try:
rlist, _, _ = select.select([self.socket,
self.sque._reader], [], [])
except socket.error:
# Terminate thread
logging.error('select failed')
self.q.put(None)
return
for r in rlist:
if r == self.sque._reader:
# Terminate
self.q.put(None)
return
elif r == self.socket:
try:
msg = self._read()
if not msg:
self.q.put(None)
return
except socket.error:
self.q.put(None)
return
# Put either to local queue or if context == 0
# callback queue
r = self.parent.decode_incoming_msg(msg)
if hasattr(r, 'context') and r.context > 0:
self.q.put(msg)
else:
self.parent.msg_handler_async(msg)
else:
raise IOError(2, 'Unknown response from select')
def connect(self, name, pfx, msg_handler, rx_qlen):
# Create a UDS socket
self.socket = socket.socket(socket.AF_UNIX, socket.SOCK_SEQPACKET)
self.socket.settimeout(self.read_timeout)
# Connect the socket to the port where the server is listening
try:
self.socket.connect(self.server_address)
except socket.error as msg:
logging.error(msg)
raise
self.connected = True
# Initialise sockclnt_create
sockclnt_create = self.parent.messages['sockclnt_create']
sockclnt_create_reply = self.parent.messages['sockclnt_create_reply']
args = {'_vl_msg_id': 15,
'name': name,
'context': 124}
b = sockclnt_create.pack(args)
self.write(b)
msg = self._read()
hdr, length = self.parent.header.unpack(msg, 0)
if hdr.msgid != 16:
raise IOError('Invalid reply message')
r, length = sockclnt_create_reply.unpack(msg)
self.socket_index = r.index
for m in r.message_table:
n = m.name.rstrip(b'\x00\x13')
self.message_table[n] = m.index
self.message_thread.daemon = True
self.message_thread.start()
return 0
def disconnect(self):
try: # Might fail, if VPP closes socket before packet makes it out
rv = self.parent.api.sockclnt_delete(index=self.socket_index)
except IOError:
pass
self.connected = False
self.socket.close()
self.sque.put(True) # Terminate listening thread
self.message_thread.join()
def suspend(self):
pass
def resume(self):
pass
def callback(self):
raise NotImplemented
def get_callback(self, async):
return self.callback
def get_msg_index(self, name):
try:
return self.message_table[name]
except KeyError:
return 0
def msg_table_max_index(self):
return len(self.message_table)
def write(self, buf):
"""Send a binary-packed message to VPP."""
if not self.connected:
raise IOError(1, 'Not connected')
# Send header
header = self.header.pack(0, len(buf), 0)
n = self.socket.send(header)
n = self.socket.send(buf)
def _read(self):
# Header and message
try:
msg = self.socket.recv(4096)
if len(msg) == 0:
return None
except socket.error as message:
logging.error(message)
raise
(_, l, _) = self.header.unpack(msg[:16])
if l > len(msg):
buf = bytearray(l + 16)
view = memoryview(buf)
view[:4096] = msg
view = view[4096:]
# Read rest of message
remaining_bytes = l - 4096 + 16
while remaining_bytes > 0:
bytes_to_read = (remaining_bytes if remaining_bytes
<= 4096 else 4096)
nbytes = self.socket.recv_into(view, bytes_to_read)
if nbytes == 0:
logging.error('recv failed')
break
view = view[nbytes:]
remaining_bytes -= nbytes
else:
buf = msg
return buf[16:]
def read(self):
if not self.connected:
raise IOError(1, 'Not connected')
return self.q.get()
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