This document describes the current stable version of py-amqp (5.0). For development docs, go here.
Source code for amqp.transport
"""Transport implementation."""
# Copyright (C) 2009 Barry Pederson <bp@barryp.org>
import errno
import os
import re
import socket
import ssl
from contextlib import contextmanager
from ssl import SSLError
from struct import pack, unpack
from .exceptions import UnexpectedFrame
from .platform import KNOWN_TCP_OPTS, SOL_TCP
from .utils import set_cloexec
_UNAVAIL = {errno.EAGAIN, errno.EINTR, errno.ENOENT, errno.EWOULDBLOCK}
AMQP_PORT = 5672
EMPTY_BUFFER = bytes()
SIGNED_INT_MAX = 0x7FFFFFFF
# Yes, Advanced Message Queuing Protocol Protocol is redundant
AMQP_PROTOCOL_HEADER = b'AMQP\x00\x00\x09\x01'
# Match things like: [fe80::1]:5432, from RFC 2732
IPV6_LITERAL = re.compile(r'\[([\.0-9a-f:]+)\](?::(\d+))?')
DEFAULT_SOCKET_SETTINGS = {
'TCP_NODELAY': 1,
'TCP_USER_TIMEOUT': 1000,
'TCP_KEEPIDLE': 60,
'TCP_KEEPINTVL': 10,
'TCP_KEEPCNT': 9,
}
[docs]def to_host_port(host, default=AMQP_PORT):
"""Convert hostname:port string to host, port tuple."""
port = default
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)
return host, port
class _AbstractTransport:
"""Common superclass for TCP and SSL transports."""
def __init__(self, host, connect_timeout=None,
read_timeout=None, write_timeout=None,
socket_settings=None, raise_on_initial_eintr=True, **kwargs):
self.connected = False
self.sock = None
self.raise_on_initial_eintr = raise_on_initial_eintr
self._read_buffer = EMPTY_BUFFER
self.host, self.port = to_host_port(host)
self.connect_timeout = connect_timeout
self.read_timeout = read_timeout
self.write_timeout = write_timeout
self.socket_settings = socket_settings
def connect(self):
try:
# are we already connected?
if self.connected:
return
self._connect(self.host, self.port, self.connect_timeout)
self._init_socket(
self.socket_settings, self.read_timeout, self.write_timeout,
)
# we've sent the banner; signal connect
# EINTR, EAGAIN, EWOULDBLOCK would signal that the banner
# has _not_ been sent
self.connected = True
except (OSError, SSLError):
# if not fully connected, close socket, and reraise error
if self.sock and not self.connected:
self.sock.close()
self.sock = None
raise
@contextmanager
def having_timeout(self, timeout):
if timeout is None:
yield self.sock
else:
sock = self.sock
prev = sock.gettimeout()
if prev != timeout:
sock.settimeout(timeout)
try:
yield self.sock
except SSLError as exc:
if 'timed out' in str(exc):
# http://bugs.python.org/issue10272
raise socket.timeout()
elif 'The operation did not complete' in str(exc):
# Non-blocking SSL sockets can throw SSLError
raise socket.timeout()
raise
except OSError as exc:
if exc.errno == errno.EWOULDBLOCK:
raise socket.timeout()
raise
finally:
if timeout != prev:
sock.settimeout(prev)
def _connect(self, host, port, timeout):
e = None
# Below we are trying to avoid additional DNS requests for AAAA if A
# succeeds. This helps a lot in case when a hostname has an IPv4 entry
# in /etc/hosts but not IPv6. Without the (arguably somewhat twisted)
# logic below, getaddrinfo would attempt to resolve the hostname for
# both IP versions, which would make the resolver talk to configured
# DNS servers. If those servers are for some reason not available
# during resolution attempt (either because of system misconfiguration,
# or network connectivity problem), resolution process locks the
# _connect call for extended time.
addr_types = (socket.AF_INET, socket.AF_INET6)
addr_types_num = len(addr_types)
for n, family in enumerate(addr_types):
# first, resolve the address for a single address family
try:
entries = socket.getaddrinfo(
host, port, family, socket.SOCK_STREAM, SOL_TCP)
entries_num = len(entries)
except socket.gaierror:
# we may have depleted all our options
if n + 1 >= addr_types_num:
# if getaddrinfo succeeded before for another address
# family, reraise the previous socket.error since it's more
# relevant to users
raise (e
if e is not None
else socket.error(
"failed to resolve broker hostname"))
continue # pragma: no cover
# now that we have address(es) for the hostname, connect to broker
for i, res in enumerate(entries):
af, socktype, proto, _, sa = res
try:
self.sock = socket.socket(af, socktype, proto)
try:
set_cloexec(self.sock, True)
except NotImplementedError:
pass
self.sock.settimeout(timeout)
self.sock.connect(sa)
except OSError as ex:
e = ex
if self.sock is not None:
self.sock.close()
self.sock = None
# we may have depleted all our options
if i + 1 >= entries_num and n + 1 >= addr_types_num:
raise
else:
# hurray, we established connection
return
def _init_socket(self, socket_settings, read_timeout, write_timeout):
self.sock.settimeout(None) # set socket back to blocking mode
self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
self._set_socket_options(socket_settings)
# set socket timeouts
for timeout, interval in ((socket.SO_SNDTIMEO, write_timeout),
(socket.SO_RCVTIMEO, read_timeout)):
if interval is not None:
sec = int(interval)
usec = int((interval - sec) * 1000000)
self.sock.setsockopt(
socket.SOL_SOCKET, timeout,
pack('ll', sec, usec),
)
self._setup_transport()
self._write(AMQP_PROTOCOL_HEADER)
def _get_tcp_socket_defaults(self, sock):
tcp_opts = {}
for opt in KNOWN_TCP_OPTS:
enum = None
if opt == 'TCP_USER_TIMEOUT':
try:
from socket import TCP_USER_TIMEOUT as enum
except ImportError:
# should be in Python 3.6+ on Linux.
enum = 18
elif hasattr(socket, opt):
enum = getattr(socket, opt)
if enum:
if opt in DEFAULT_SOCKET_SETTINGS:
tcp_opts[enum] = DEFAULT_SOCKET_SETTINGS[opt]
elif hasattr(socket, opt):
tcp_opts[enum] = sock.getsockopt(
SOL_TCP, getattr(socket, opt))
return tcp_opts
def _set_socket_options(self, socket_settings):
tcp_opts = self._get_tcp_socket_defaults(self.sock)
if socket_settings:
tcp_opts.update(socket_settings)
for opt, val in tcp_opts.items():
self.sock.setsockopt(SOL_TCP, opt, val)
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."""
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
read_frame_buffer = EMPTY_BUFFER
try:
frame_header = read(7, True)
read_frame_buffer += frame_header
frame_type, channel, size = unpack('>BHI', frame_header)
# >I is an unsigned int, but the argument to sock.recv is signed,
# so we know the size can be at most 2 * SIGNED_INT_MAX
if size > SIGNED_INT_MAX:
part1 = read(SIGNED_INT_MAX)
try:
part2 = read(size - SIGNED_INT_MAX)
except (socket.timeout, OSError, SSLError):
# In case this read times out, we need to make sure to not
# lose part1 when we retry the read
read_frame_buffer += part1
raise
payload = b''.join([part1, part2])
else:
payload = read(size)
read_frame_buffer += payload
ch = ord(read(1))
except socket.timeout:
self._read_buffer = read_frame_buffer + self._read_buffer
raise
except (OSError, SSLError) as exc:
if (
isinstance(exc, socket.error) and os.name == 'nt'
and exc.errno == errno.EWOULDBLOCK # noqa
):
# On windows we can get a read timeout with a winsock error
# code instead of a proper socket.timeout() error, see
# https://github.com/celery/py-amqp/issues/320
self._read_buffer = read_frame_buffer + self._read_buffer
raise socket.timeout()
if isinstance(exc, SSLError) and 'timed out' in str(exc):
# Don't disconnect for ssl read time outs
# http://bugs.python.org/issue10272
self._read_buffer = read_frame_buffer + self._read_buffer
raise socket.timeout()
if exc.errno not in _UNAVAIL:
self.connected = False
raise
if ch == 206: # '\xce'
return frame_type, channel, payload
else:
raise UnexpectedFrame(
f'Received {ch:#04x} while expecting 0xce')
def write(self, s):
try:
self._write(s)
except socket.timeout:
raise
except OSError as exc:
if exc.errno not in _UNAVAIL:
self.connected = False
raise
[docs]class SSLTransport(_AbstractTransport):
"""Transport that works over SSL."""
def __init__(self, host, connect_timeout=None, ssl=None, **kwargs):
self.sslopts = ssl if isinstance(ssl, dict) else {}
self._read_buffer = EMPTY_BUFFER
super().__init__(
host, connect_timeout=connect_timeout, **kwargs)
def _setup_transport(self):
"""Wrap the socket in an SSL object."""
self.sock = self._wrap_socket(self.sock, **self.sslopts)
self.sock.do_handshake()
self._quick_recv = self.sock.read
def _wrap_socket(self, sock, context=None, **sslopts):
if context:
return self._wrap_context(sock, sslopts, **context)
return self._wrap_socket_sni(sock, **sslopts)
def _wrap_context(self, sock, sslopts, check_hostname=None, **ctx_options):
ctx = ssl.create_default_context(**ctx_options)
ctx.check_hostname = check_hostname
return ctx.wrap_socket(sock, **sslopts)
def _wrap_socket_sni(self, sock, keyfile=None, certfile=None,
server_side=False, cert_reqs=ssl.CERT_NONE,
do_handshake_on_connect=False,
suppress_ragged_eofs=True, server_hostname=None,
ssl_version=ssl.PROTOCOL_TLS):
"""Socket wrap with SNI headers.
stdlib `ssl.SSLContext.wrap_socket` method augmented with support for
setting the server_hostname field required for SNI hostname header
"""
opts = {
'sock': sock,
'server_side': server_side,
'do_handshake_on_connect': do_handshake_on_connect,
'suppress_ragged_eofs': suppress_ragged_eofs,
'server_hostname': server_hostname,
}
context = ssl.SSLContext(ssl_version)
if certfile is not None:
context.load_cert_chain(certfile, keyfile)
if cert_reqs != ssl.CERT_NONE:
context.check_hostname = True
# Set SNI headers if supported
if (server_hostname is not None) and (
hasattr(ssl, 'HAS_SNI') and ssl.HAS_SNI) and (
hasattr(ssl, 'SSLContext')):
context.verify_mode = cert_reqs
sock = context.wrap_socket(**opts)
return sock
def _shutdown_transport(self):
"""Unwrap a SSL socket, so we can call shutdown()."""
if self.sock is not None:
self.sock = 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(n - len(rbuf)) # see note above
except OSError as exc:
# ssl.sock.read may cause ENOENT if the
# operation couldn't be performed (Issue celery#1414).
if exc.errno in _errnos:
if initial and self.raise_on_initial_eintr:
raise socket.timeout()
continue
raise
if not s:
raise OSError('Server unexpectedly closed connection')
rbuf += s
except: # noqa
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:
try:
n = write(s)
except ValueError:
# AG: sock._sslobj might become null in the meantime if the
# remote connection has hung up.
# In python 3.4, a ValueError is raised is self._sslobj is
# None.
n = 0
if not n:
raise OSError('Socket closed')
s = s[n:]
[docs]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(n - len(rbuf))
except OSError as exc:
if exc.errno in _errnos:
if initial and self.raise_on_initial_eintr:
raise socket.timeout()
continue
raise
if not s:
raise OSError('Server unexpectedly closed connection')
rbuf += s
except: # noqa
self._read_buffer = rbuf
raise
result, self._read_buffer = rbuf[:n], rbuf[n:]
return result
[docs]def Transport(host, connect_timeout=None, ssl=False, **kwargs):
"""Create transport.
Given a few parameters from the Connection constructor,
select and create a subclass of _AbstractTransport.
"""
transport = SSLTransport if ssl else TCPTransport
return transport(host, connect_timeout=connect_timeout, ssl=ssl, **kwargs)
