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#!/usr/bin/env python
from __future__ import absolute_import, division, with_statement
from tornado.escape import utf8, _unicode, native_str
from tornado.httpclient import HTTPRequest, HTTPResponse, HTTPError, AsyncHTTPClient, main
from tornado.httputil import HTTPHeaders
from tornado.iostream import IOStream, SSLIOStream
from tornado.log import gen_log
from tornado import stack_context
from tornado.util import b, GzipDecompressor
import base64
import collections
import contextlib
import copy
import functools
import os.path
import re
import socket
import sys
import time
import urlparse
from io import BytesIO # python 3
except ImportError:
from cStringIO import StringIO as BytesIO # python 2
import ssl # python 2.6+
except ImportError:
ssl = None
_DEFAULT_CA_CERTS = os.path.dirname(__file__) + '/ca-certificates.crt'
class SimpleAsyncHTTPClient(AsyncHTTPClient):
"""Non-blocking HTTP client with no external dependencies.
This class implements an HTTP 1.1 client on top of Tornado's IOStreams.
It does not currently implement all applicable parts of the HTTP
specification, but it does enough to work with major web service APIs
(mostly tested against the Twitter API so far).
This class has not been tested extensively in production and
should be considered somewhat experimental as of the release of
tornado 1.2. It is intended to become the default AsyncHTTPClient
implementation in a future release. It may either be used
directly, or to facilitate testing of this class with an existing
application, setting the environment variable
USE_SIMPLE_HTTPCLIENT=1 will cause this class to transparently
replace tornado.httpclient.AsyncHTTPClient.
Some features found in the curl-based AsyncHTTPClient are not yet
supported. In particular, proxies are not supported, connections
are not reused, and callers cannot select the network interface to be
Python 2.6 or higher is required for HTTPS support. Users of Python 2.5
should use the curl-based AsyncHTTPClient if HTTPS support is required.
def initialize(self, io_loop=None, max_clients=10,
hostname_mapping=None, max_buffer_size=104857600):
"""Creates a AsyncHTTPClient.
Only a single AsyncHTTPClient instance exists per IOLoop
in order to provide limitations on the number of pending connections.
force_instance=True may be used to suppress this behavior.
max_clients is the number of concurrent requests that can be
in progress. Note that this arguments are only used when the
client is first created, and will be ignored when an existing
client is reused.
hostname_mapping is a dictionary mapping hostnames to IP addresses.
It can be used to make local DNS changes when modifying system-wide
settings like /etc/hosts is not possible or desirable (e.g. in
max_buffer_size is the number of bytes that can be read by IOStream. It
defaults to 100mb.
self.io_loop = io_loop
self.max_clients = max_clients
self.queue = collections.deque() = {}
self.hostname_mapping = hostname_mapping
self.max_buffer_size = max_buffer_size
def fetch(self, request, callback, **kwargs):
if not isinstance(request, HTTPRequest):
request = HTTPRequest(url=request, **kwargs)
# We're going to modify this (to add Host, Accept-Encoding, etc),
# so make sure we don't modify the caller's object. This is also
# where normal dicts get converted to HTTPHeaders objects.
request.headers = HTTPHeaders(request.headers)
callback = stack_context.wrap(callback)
self.queue.append((request, callback))
if self.queue:
gen_log.debug("max_clients limit reached, request queued. "
"%d active, %d queued requests." % (
len(, len(self.queue)))
def _process_queue(self):
with stack_context.NullContext():
while self.queue and len( < self.max_clients:
request, callback = self.queue.popleft()
key = object()[key] = (request, callback)
_HTTPConnection(self.io_loop, self, request,
functools.partial(self._release_fetch, key),
def _release_fetch(self, key):
class _HTTPConnection(object):
def __init__(self, io_loop, client, request, release_callback,
final_callback, max_buffer_size):
self.start_time = time.time()
self.io_loop = io_loop
self.client = client
self.request = request
self.release_callback = release_callback
self.final_callback = final_callback
self.code = None
self.headers = None
self.chunks = None
self._decompressor = None
# Timeout handle returned by IOLoop.add_timeout
self._timeout = None
with stack_context.StackContext(self.cleanup):
parsed = urlparse.urlsplit(_unicode(self.request.url))
if ssl is None and parsed.scheme == "https":
raise ValueError("HTTPS requires either python2.6+ or "
if parsed.scheme not in ("http", "https"):
raise ValueError("Unsupported url scheme: %s" %
# urlsplit results have hostname and port results, but they
# didn't support ipv6 literals until python 2.7.
netloc = parsed.netloc
if "@" in netloc:
userpass, _, netloc = netloc.rpartition("@")
match = re.match(r'^(.+):(\d+)$', netloc)
if match:
host =
port = int(
host = netloc
port = 443 if parsed.scheme == "https" else 80
if re.match(r'^\[.*\]$', host):
# raw ipv6 addresses in urls are enclosed in brackets
host = host[1:-1]
parsed_hostname = host # save final parsed host for _on_connect
if self.client.hostname_mapping is not None:
host = self.client.hostname_mapping.get(host, host)
if request.allow_ipv6:
af = socket.AF_UNSPEC
# We only try the first IP we get from getaddrinfo,
# so restrict to ipv4 by default.
af = socket.AF_INET
addrinfo = socket.getaddrinfo(host, port, af, socket.SOCK_STREAM,
0, 0)
af, socktype, proto, canonname, sockaddr = addrinfo[0]
if parsed.scheme == "https":
ssl_options = {}
if request.validate_cert:
ssl_options["cert_reqs"] = ssl.CERT_REQUIRED
if request.ca_certs is not None:
ssl_options["ca_certs"] = request.ca_certs
ssl_options["ca_certs"] = _DEFAULT_CA_CERTS
if request.client_key is not None:
ssl_options["keyfile"] = request.client_key
if request.client_cert is not None:
ssl_options["certfile"] = request.client_cert
# SSL interoperability is tricky. We want to disable
# SSLv2 for security reasons; it wasn't disabled by default
# until openssl 1.0. The best way to do this is to use
# the SSL_OP_NO_SSLv2, but that wasn't exposed to python
# until 3.2. Python 2.7 adds the ciphers argument, which
# can also be used to disable SSLv2. As a last resort
# on python 2.6, we set ssl_version to SSLv3. This is
# more narrow than we'd like since it also breaks
# compatibility with servers configured for TLSv1 only,
# but nearly all servers support SSLv3:
if sys.version_info >= (2, 7):
ssl_options["ciphers"] = "DEFAULT:!SSLv2"
# This is really only necessary for pre-1.0 versions
# of openssl, but python 2.6 doesn't expose version
# information.
ssl_options["ssl_version"] = ssl.PROTOCOL_SSLv3 = SSLIOStream(socket.socket(af, socktype, proto),
else: = IOStream(socket.socket(af, socktype, proto),
timeout = min(request.connect_timeout, request.request_timeout)
if timeout:
self._timeout = self.io_loop.add_timeout(
self.start_time + timeout,
functools.partial(self._on_connect, parsed,
def _on_timeout(self):
self._timeout = None
if self.final_callback is not None:
raise HTTPError(599, "Timeout")
def _on_connect(self, parsed, parsed_hostname):
if self._timeout is not None:
self._timeout = None
if self.request.request_timeout:
self._timeout = self.io_loop.add_timeout(
self.start_time + self.request.request_timeout,
if (self.request.validate_cert and
isinstance(, SSLIOStream)):
# ipv6 addresses are broken (in
# parsed.hostname) until 2.7, here is
# correctly parsed value calculated in
# __init__
if (self.request.method not in self._SUPPORTED_METHODS and
not self.request.allow_nonstandard_methods):
raise KeyError("unknown method %s" % self.request.method)
for key in ('network_interface',
'proxy_host', 'proxy_port',
'proxy_username', 'proxy_password'):
if getattr(self.request, key, None):
raise NotImplementedError('%s not supported' % key)
if "Connection" not in self.request.headers:
self.request.headers["Connection"] = "close"
if "Host" not in self.request.headers:
if '@' in parsed.netloc:
self.request.headers["Host"] = parsed.netloc.rpartition('@')[-1]
self.request.headers["Host"] = parsed.netloc
username, password = None, None
if parsed.username is not None:
username, password = parsed.username, parsed.password
elif self.request.auth_username is not None:
username = self.request.auth_username
password = self.request.auth_password or ''
if username is not None:
auth = utf8(username) + b(":") + utf8(password)
self.request.headers["Authorization"] = (b("Basic ") +
if self.request.user_agent:
self.request.headers["User-Agent"] = self.request.user_agent
if not self.request.allow_nonstandard_methods:
if self.request.method in ("POST", "PATCH", "PUT"):
assert self.request.body is not None
assert self.request.body is None
if self.request.body is not None:
self.request.headers["Content-Length"] = str(len(
if (self.request.method == "POST" and
"Content-Type" not in self.request.headers):
self.request.headers["Content-Type"] = "application/x-www-form-urlencoded"
if self.request.use_gzip:
self.request.headers["Accept-Encoding"] = "gzip"
req_path = ((parsed.path or '/') +
(('?' + parsed.query) if parsed.query else ''))
request_lines = [utf8("%s %s HTTP/1.1" % (self.request.method,
for k, v in self.request.headers.get_all():
line = utf8(k) + b(": ") + utf8(v)
if b('\n') in line:
raise ValueError('Newline in header: ' + repr(line))
request_lines.append(line)"\r\n").join(request_lines) + b("\r\n\r\n"))
if self.request.body is not None:"\r?\n\r?\n"), self._on_headers)
def _release(self):
if self.release_callback is not None:
release_callback = self.release_callback
self.release_callback = None
def _run_callback(self, response):
if self.final_callback is not None:
final_callback = self.final_callback
self.final_callback = None
def cleanup(self):
except Exception, e:
gen_log.warning("uncaught exception", exc_info=True)
self._run_callback(HTTPResponse(self.request, 599, error=e,
request_time=time.time() - self.start_time,
if hasattr(self, "stream"):
def _on_close(self):
if self.final_callback is not None:
message = "Connection closed"
message = str(
raise HTTPError(599, message)
def _on_headers(self, data):
data = native_str(data.decode("latin1"))
first_line, _, header_data = data.partition("\n")
match = re.match("HTTP/1.[01] ([0-9]+)", first_line)
assert match
code = int(
if 100 <= code < 200:"\r?\n\r?\n"), self._on_headers)
self.code = code
self.headers = HTTPHeaders.parse(header_data)
if "Content-Length" in self.headers:
if "," in self.headers["Content-Length"]:
# Proxies sometimes cause Content-Length headers to get
# duplicated. If all the values are identical then we can
# use them but if they differ it's an error.
pieces = re.split(r',\s*', self.headers["Content-Length"])
if any(i != pieces[0] for i in pieces):
raise ValueError("Multiple unequal Content-Lengths: %r" %
self.headers["Content-Length"] = pieces[0]
content_length = int(self.headers["Content-Length"])
content_length = None
if self.request.header_callback is not None:
for k, v in self.headers.get_all():
self.request.header_callback("%s: %s\r\n" % (k, v))
if self.request.method == "HEAD":
# HEAD requests never have content, even though they may have
# content-length headers
if 100 <= self.code < 200 or self.code in (204, 304):
# These response codes never have bodies
if ("Transfer-Encoding" in self.headers or
content_length not in (None, 0)):
raise ValueError("Response with code %d should not have body" %
if (self.request.use_gzip and
self.headers.get("Content-Encoding") == "gzip"):
self._decompressor = GzipDecompressor()
if self.headers.get("Transfer-Encoding") == "chunked":
self.chunks = []"\r\n"), self._on_chunk_length)
elif content_length is not None:, self._on_body)
def _on_body(self, data):
if self._timeout is not None:
self._timeout = None
original_request = getattr(self.request, "original_request",
if (self.request.follow_redirects and
self.request.max_redirects > 0 and
self.code in (301, 302, 303, 307)):
new_request = copy.copy(self.request)
new_request.url = urlparse.urljoin(self.request.url,
new_request.max_redirects -= 1
del new_request.headers["Host"]
# client SHOULD make a GET request
if self.code == 303:
new_request.method = "GET"
new_request.body = None
for h in ["Content-Length", "Content-Type",
"Content-Encoding", "Transfer-Encoding"]:
del self.request.headers[h]
except KeyError:
new_request.original_request = original_request
final_callback = self.final_callback
self.final_callback = None
self.client.fetch(new_request, final_callback)
if self._decompressor:
data = (self._decompressor.decompress(data) +
if self.request.streaming_callback:
if self.chunks is None:
# if chunks is not None, we already called streaming_callback
# in _on_chunk_data
buffer = BytesIO()
buffer = BytesIO(data) # TODO: don't require one big string?
response = HTTPResponse(original_request,
self.code, headers=self.headers,
request_time=time.time() - self.start_time,
def _on_chunk_length(self, data):
# TODO: "chunk extensions"
length = int(data.strip(), 16)
if length == 0:
if self._decompressor is not None:
tail = self._decompressor.flush()
if tail:
# I believe the tail will always be empty (i.e.
# decompress will return all it can). The purpose
# of the flush call is to detect errors such
# as truncated input. But in case it ever returns
# anything, treat it as an extra chunk
if self.request.streaming_callback is not None:
# all the data has been decompressed, so we don't need to
# decompress again in _on_body
self._decompressor = None
else: + 2, # chunk ends with \r\n
def _on_chunk_data(self, data):
assert data[-2:] == b("\r\n")
chunk = data[:-2]
if self._decompressor:
chunk = self._decompressor.decompress(chunk)
if self.request.streaming_callback is not None:
self.chunks.append(chunk)"\r\n"), self._on_chunk_length)
# match_hostname was added to the standard library ssl module in python 3.2.
# The following code was backported for older releases and copied from
class CertificateError(ValueError):
def _dnsname_to_pat(dn):
pats = []
for frag in dn.split(r'.'):
if frag == '*':
# When '*' is a fragment by itself, it matches a non-empty dotless
# fragment.
# Otherwise, '*' matches any dotless fragment.
frag = re.escape(frag)
pats.append(frag.replace(r'\*', '[^.]*'))
return re.compile(r'\A' + r'\.'.join(pats) + r'\Z', re.IGNORECASE)
def match_hostname(cert, hostname):
"""Verify that *cert* (in decoded format as returned by
SSLSocket.getpeercert()) matches the *hostname*. RFC 2818 rules
are mostly followed, but IP addresses are not accepted for *hostname*.
CertificateError is raised on failure. On success, the function
returns nothing.
if not cert:
raise ValueError("empty or no certificate")
dnsnames = []
san = cert.get('subjectAltName', ())
for key, value in san:
if key == 'DNS':
if _dnsname_to_pat(value).match(hostname):
if not san:
# The subject is only checked when subjectAltName is empty
for sub in cert.get('subject', ()):
for key, value in sub:
# XXX according to RFC 2818, the most specific Common Name
# must be used.
if key == 'commonName':
if _dnsname_to_pat(value).match(hostname):
if len(dnsnames) > 1:
raise CertificateError("hostname %r "
"doesn't match either of %s"
% (hostname, ', '.join(map(repr, dnsnames))))
elif len(dnsnames) == 1:
raise CertificateError("hostname %r "
"doesn't match %r"
% (hostname, dnsnames[0]))
raise CertificateError("no appropriate commonName or "
"subjectAltName fields were found")
if __name__ == "__main__":
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