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"""
Read/Write AMQP frames over network transports.
2009-01-14 Barry Pederson <bp@barryp.org>
"""
# Copyright (C) 2009 Barry Pederson <bp@barryp.org>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
from __future__ import absolute_import
import errno
import re
import socket
# Jython does not have this attribute
try:
from socket import SOL_TCP
except ImportError: # pragma: no cover
from socket import IPPROTO_TCP as SOL_TCP # noqa
#
# See if Python 2.6+ SSL support is available
#
try:
import ssl
HAVE_PY26_SSL = True
except:
HAVE_PY26_SSL = False
try:
bytes
except:
# Python 2.5 and lower
bytes = str
from struct import pack, unpack
from .exceptions import UnexpectedFrame
from .utils import get_errno, set_cloexec
_UNAVAIL = errno.EAGAIN, errno.EINTR
AMQP_PORT = 5672
EMPTY_BUFFER = bytes()
# Yes, Advanced Message Queuing Protocol Protocol is redundant
AMQP_PROTOCOL_HEADER = 'AMQP\x01\x01\x00\x09'.encode('latin_1')
# Match things like: [fe80::1]:5432, from RFC 2732
IPV6_LITERAL = re.compile(r'\[([\.0-9a-f:]+)\](?::(\d+))?')
class _AbstractTransport(object):
"""Common superclass for TCP and SSL transports"""
connected = False
def __init__(self, host, connect_timeout):
self.connected = True
msg = None
port = AMQP_PORT
m = IPV6_LITERAL.match(host)
if m:
host = m.group(1)
if m.group(2):
port = int(m.group(2))
else:
if ':' in host:
host, port = host.rsplit(':', 1)
port = int(port)
self.sock = None
last_err = None
for res in socket.getaddrinfo(host, port, 0,
socket.SOCK_STREAM, SOL_TCP):
af, socktype, proto, canonname, sa = res
try:
self.sock = socket.socket(af, socktype, proto)
try:
set_cloexec(self.sock, True)
except NotImplementedError:
pass
self.sock.settimeout(connect_timeout)
self.sock.connect(sa)
except socket.error as exc:
msg = exc
self.sock.close()
self.sock = None
last_err = msg
continue
break
if not self.sock:
# Didn't connect, return the most recent error message
raise socket.error(last_err)
try:
self.sock.settimeout(None)
self.sock.setsockopt(SOL_TCP, socket.TCP_NODELAY, 1)
self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
self._setup_transport()
self._write(AMQP_PROTOCOL_HEADER)
except (OSError, IOError, socket.error) as exc:
if get_errno(exc) not in _UNAVAIL:
self.connected = False
raise
def __del__(self):
try:
self.close()
except socket.error:
pass
finally:
self.sock = None
def _read(self, n, initial=False):
"""Read exactly n bytes from the peer"""
raise NotImplementedError('Must be overriden in subclass')
def _setup_transport(self):
"""Do any additional initialization of the class (used
by the subclasses)."""
pass
def _shutdown_transport(self):
"""Do any preliminary work in shutting down the connection."""
pass
def _write(self, s):
"""Completely write a string to the peer."""
raise NotImplementedError('Must be overriden in subclass')
def close(self):
if self.sock is not None:
self._shutdown_transport()
# Call shutdown first to make sure that pending messages
# reach the AMQP broker if the program exits after
# calling this method.
self.sock.shutdown(socket.SHUT_RDWR)
self.sock.close()
self.sock = None
self.connected = False
def read_frame(self, unpack=unpack):
read = self._read
try:
frame_type, channel, size = unpack('>BHI', read(7, True))
payload = read(size)
ch = ord(read(1))
except socket.timeout:
raise
except (OSError, IOError, socket.error) as exc:
if get_errno(exc) not in _UNAVAIL:
self.connected = False
raise
if ch == 206: # '\xce'
return frame_type, channel, payload
else:
raise UnexpectedFrame(
'Received 0x{0:02x} while expecting 0xce'.format(ch))
def write_frame(self, frame_type, channel, payload):
size = len(payload)
try:
self._write(pack(
'>BHI%dsB' % size,
frame_type, channel, size, payload, 0xce,
))
except socket.timeout:
raise
except (OSError, IOError, socket.error) as exc:
if get_errno(exc) not in _UNAVAIL:
self.connected = False
raise
class SSLTransport(_AbstractTransport):
"""Transport that works over SSL"""
def __init__(self, host, connect_timeout, ssl):
if isinstance(ssl, dict):
self.sslopts = ssl
self._read_buffer = EMPTY_BUFFER
super(SSLTransport, self).__init__(host, connect_timeout)
def _setup_transport(self):
"""Wrap the socket in an SSL object, either the
new Python 2.6 version, or the older Python 2.5 and
lower version."""
if HAVE_PY26_SSL:
if hasattr(self, 'sslopts'):
self.sock = ssl.wrap_socket(self.sock, **self.sslopts)
else:
self.sock = ssl.wrap_socket(self.sock)
self.sock.do_handshake()
else:
self.sock = socket.ssl(self.sock)
self._quick_recv = self.sock.read
def _shutdown_transport(self):
"""Unwrap a Python 2.6 SSL socket, so we can call shutdown()"""
if HAVE_PY26_SSL and self.sock is not None:
try:
unwrap = self.sock.unwrap
except AttributeError:
return
self.sock = unwrap()
def _read(self, n, initial=False,
_errnos=(errno.ENOENT, errno.EAGAIN, errno.EINTR)):
# According to SSL_read(3), it can at most return 16kb of data.
# Thus, we use an internal read buffer like TCPTransport._read
# to get the exact number of bytes wanted.
recv = self._quick_recv
rbuf = self._read_buffer
try:
while len(rbuf) < n:
try:
s = recv(131072) # see note above
except socket.error as exc:
# ssl.sock.read may cause ENOENT if the
# operation couldn't be performed (Issue celery#1414).
if not initial and exc.errno in _errnos:
continue
raise
if not s:
raise IOError('Socket closed')
rbuf += s
except:
self._read_buffer = rbuf
raise
result, self._read_buffer = rbuf[:n], rbuf[n:]
return result
def _write(self, s):
"""Write a string out to the SSL socket fully."""
write = self.sock.write
while s:
n = write(s)
if not n:
raise IOError('Socket closed')
s = s[n:]
class TCPTransport(_AbstractTransport):
"""Transport that deals directly with TCP socket."""
def _setup_transport(self):
"""Setup to _write() directly to the socket, and
do our own buffered reads."""
self._write = self.sock.sendall
self._read_buffer = EMPTY_BUFFER
self._quick_recv = self.sock.recv
def _read(self, n, initial=False, _errnos=(errno.EAGAIN, errno.EINTR)):
"""Read exactly n bytes from the socket"""
recv = self._quick_recv
rbuf = self._read_buffer
try:
while len(rbuf) < n:
try:
s = recv(131072)
except socket.error as exc:
if not initial and exc.errno in _errnos:
continue
raise
if not s:
raise IOError('Socket closed')
rbuf += s
except:
self._read_buffer = rbuf
raise
result, self._read_buffer = rbuf[:n], rbuf[n:]
return result
def create_transport(host, connect_timeout, ssl=False):
"""Given a few parameters from the Connection constructor,
select and create a subclass of _AbstractTransport."""
if ssl:
return SSLTransport(host, connect_timeout, ssl)
else:
return TCPTransport(host, connect_timeout)
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