Current File : //lib/python3.6/site-packages/urllib3/util/connection.py
from __future__ import absolute_import
import socket
from .wait import NoWayToWaitForSocketError, wait_for_read
from ..contrib import _appengine_environ
def is_connection_dropped(conn): # Platform-specific
"""
Returns True if the connection is dropped and should be closed.
:param conn:
:class:`httplib.HTTPConnection` object.
Note: For platforms like AppEngine, this will always return ``False`` to
let the platform handle connection recycling transparently for us.
"""
sock = getattr(conn, 'sock', False)
if sock is False: # Platform-specific: AppEngine
return False
if sock is None: # Connection already closed (such as by httplib).
return True
try:
# Returns True if readable, which here means it's been dropped
return wait_for_read(sock, timeout=0.0)
except NoWayToWaitForSocketError: # Platform-specific: AppEngine
return False
# This function is copied from socket.py in the Python 2.7 standard
# library test suite. Added to its signature is only `socket_options`.
# One additional modification is that we avoid binding to IPv6 servers
# discovered in DNS if the system doesn't have IPv6 functionality.
def create_connection(address, timeout=socket._GLOBAL_DEFAULT_TIMEOUT,
source_address=None, socket_options=None):
"""Connect to *address* and return the socket object.
Convenience function. Connect to *address* (a 2-tuple ``(host,
port)``) and return the socket object. Passing the optional
*timeout* parameter will set the timeout on the socket instance
before attempting to connect. If no *timeout* is supplied, the
global default timeout setting returned by :func:`getdefaulttimeout`
is used. If *source_address* is set it must be a tuple of (host, port)
for the socket to bind as a source address before making the connection.
An host of '' or port 0 tells the OS to use the default.
"""
host, port = address
if host.startswith('['):
host = host.strip('[]')
err = None
# Using the value from allowed_gai_family() in the context of getaddrinfo lets
# us select whether to work with IPv4 DNS records, IPv6 records, or both.
# The original create_connection function always returns all records.
family = allowed_gai_family()
for res in socket.getaddrinfo(host, port, family, socket.SOCK_STREAM):
af, socktype, proto, canonname, sa = res
sock = None
try:
sock = socket.socket(af, socktype, proto)
# If provided, set socket level options before connecting.
_set_socket_options(sock, socket_options)
if timeout is not socket._GLOBAL_DEFAULT_TIMEOUT:
sock.settimeout(timeout)
if source_address:
sock.bind(source_address)
sock.connect(sa)
return sock
except socket.error as e:
err = e
if sock is not None:
sock.close()
sock = None
if err is not None:
raise err
raise socket.error("getaddrinfo returns an empty list")
def _set_socket_options(sock, options):
if options is None:
return
for opt in options:
sock.setsockopt(*opt)
def allowed_gai_family():
"""This function is designed to work in the context of
getaddrinfo, where family=socket.AF_UNSPEC is the default and
will perform a DNS search for both IPv6 and IPv4 records."""
family = socket.AF_INET
if HAS_IPV6:
family = socket.AF_UNSPEC
return family
def _has_ipv6(host):
""" Returns True if the system can bind an IPv6 address. """
sock = None
has_ipv6 = False
# App Engine doesn't support IPV6 sockets and actually has a quota on the
# number of sockets that can be used, so just early out here instead of
# creating a socket needlessly.
# See https://github.com/urllib3/urllib3/issues/1446
if _appengine_environ.is_appengine_sandbox():
return False
if socket.has_ipv6:
# has_ipv6 returns true if cPython was compiled with IPv6 support.
# It does not tell us if the system has IPv6 support enabled. To
# determine that we must bind to an IPv6 address.
# https://github.com/shazow/urllib3/pull/611
# https://bugs.python.org/issue658327
try:
sock = socket.socket(socket.AF_INET6)
sock.bind((host, 0))
has_ipv6 = True
except Exception:
pass
if sock:
sock.close()
return has_ipv6
HAS_IPV6 = _has_ipv6('::1')
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