"""HTTP/1.1 client library

<intro stuff goes here>

<other stuff, too>

HTTPConnection goes through a number of "states", which define when a client

may legally make another request or fetch the response for a particular

request. This diagram details these state transitions:

(null)

|

| HTTPConnection()

v

Idle

|

| putrequest()

v

Request-started

|

| ( putheader() )* endheaders()

v

Request-sent

|

| response = getresponse()

v

Unread-response [Response-headers-read]

|\____________________

| |

| response.read() | putrequest()

v v

Idle Req-started-unread-response

______/|

/ |

response.read() | | ( putheader() )* endheaders()

v v

Request-started Req-sent-unread-response

|

| response.read()

v

Request-sent

This diagram presents the following rules:

-- a second request may not be started until {response-headers-read}

-- a response [object] cannot be retrieved until {request-sent}

-- there is no differentiation between an unread response body and a

partially read response body

Note: this enforcement is applied by the HTTPConnection class. The

HTTPResponse class does not enforce this state machine, which

implies sophisticated clients may accelerate the request/response

pipeline. Caution should be taken, though: accelerating the states

beyond the above pattern may imply knowledge of the server's

connection-close behavior for certain requests. For example, it

is impossible to tell whether the server will close the connection

UNTIL the response headers have been read; this means that further

requests cannot be placed into the pipeline until it is known that

the server will NOT be closing the connection.

Logical State __state __response

------------- ------- ----------

Idle _CS_IDLE None

Request-started _CS_REQ_STARTED None

Request-sent _CS_REQ_SENT None

Unread-response _CS_IDLE <response_class>

Req-started-unread-response _CS_REQ_STARTED <response_class>

Req-sent-unread-response _CS_REQ_SENT <response_class>

"""

import email.parser

import email.message

import io

import os

import socket

import collections

from urllib.parse import urlsplit

import warnings

__all__ = ["HTTPResponse", "HTTPConnection",

"HTTPException", "NotConnected", "UnknownProtocol",

"UnknownTransferEncoding", "UnimplementedFileMode",

"IncompleteRead", "InvalidURL", "ImproperConnectionState",

"CannotSendRequest", "CannotSendHeader", "ResponseNotReady",

"BadStatusLine", "error", "responses"]

HTTP_PORT = 80

HTTPS_PORT = 443

_UNKNOWN = 'UNKNOWN'

# connection states

_CS_IDLE = 'Idle'

_CS_REQ_STARTED = 'Request-started'

_CS_REQ_SENT = 'Request-sent'

# status codes

# informational

CONTINUE = 100

SWITCHING_PROTOCOLS = 101

PROCESSING = 102

# successful

OK = 200

CREATED = 201

ACCEPTED = 202

NON_AUTHORITATIVE_INFORMATION = 203

NO_CONTENT = 204

RESET_CONTENT = 205

PARTIAL_CONTENT = 206

MULTI_STATUS = 207

IM_USED = 226

# redirection

MULTIPLE_CHOICES = 300

MOVED_PERMANENTLY = 301

FOUND = 302

SEE_OTHER = 303

NOT_MODIFIED = 304

USE_PROXY = 305

TEMPORARY_REDIRECT = 307

# client error

BAD_REQUEST = 400

UNAUTHORIZED = 401

PAYMENT_REQUIRED = 402

FORBIDDEN = 403

NOT_FOUND = 404

METHOD_NOT_ALLOWED = 405

NOT_ACCEPTABLE = 406

PROXY_AUTHENTICATION_REQUIRED = 407

REQUEST_TIMEOUT = 408

CONFLICT = 409

GONE = 410

LENGTH_REQUIRED = 411

PRECONDITION_FAILED = 412

REQUEST_ENTITY_TOO_LARGE = 413

REQUEST_URI_TOO_LONG = 414

UNSUPPORTED_MEDIA_TYPE = 415

REQUESTED_RANGE_NOT_SATISFIABLE = 416

EXPECTATION_FAILED = 417

UNPROCESSABLE_ENTITY = 422

LOCKED = 423

FAILED_DEPENDENCY = 424

UPGRADE_REQUIRED = 426

PRECONDITION_REQUIRED = 428

TOO_MANY_REQUESTS = 429

REQUEST_HEADER_FIELDS_TOO_LARGE = 431

# server error

INTERNAL_SERVER_ERROR = 500

NOT_IMPLEMENTED = 501

BAD_GATEWAY = 502

SERVICE_UNAVAILABLE = 503

GATEWAY_TIMEOUT = 504

HTTP_VERSION_NOT_SUPPORTED = 505

INSUFFICIENT_STORAGE = 507

NOT_EXTENDED = 510

NETWORK_AUTHENTICATION_REQUIRED = 511

# Mapping status codes to official W3C names

responses = {

100: 'Continue',

101: 'Switching Protocols',

200: 'OK',

201: 'Created',

202: 'Accepted',

203: 'Non-Authoritative Information',

204: 'No Content',

205: 'Reset Content',

206: 'Partial Content',

300: 'Multiple Choices',

301: 'Moved Permanently',

302: 'Found',

303: 'See Other',

304: 'Not Modified',

305: 'Use Proxy',

306: '(Unused)',

307: 'Temporary Redirect',

400: 'Bad Request',

401: 'Unauthorized',

402: 'Payment Required',

403: 'Forbidden',

404: 'Not Found',

405: 'Method Not Allowed',

406: 'Not Acceptable',

407: 'Proxy Authentication Required',

408: 'Request Timeout',

409: 'Conflict',

410: 'Gone',

411: 'Length Required',

412: 'Precondition Failed',

413: 'Request Entity Too Large',

414: 'Request-URI Too Long',

415: 'Unsupported Media Type',

416: 'Requested Range Not Satisfiable',

417: 'Expectation Failed',

428: 'Precondition Required',

429: 'Too Many Requests',

431: 'Request Header Fields Too Large',

500: 'Internal Server Error',

501: 'Not Implemented',

502: 'Bad Gateway',

503: 'Service Unavailable',

504: 'Gateway Timeout',

505: 'HTTP Version Not Supported',

511: 'Network Authentication Required',

}

# maximal amount of data to read at one time in _safe_read

MAXAMOUNT = 1048576

# maximal line length when calling readline().

_MAXLINE = 65536

class HTTPMessage(email.message.Message):

# XXX The only usage of this method is in

# http.server.CGIHTTPRequestHandler. Maybe move the code there so

# that it doesn't need to be part of the public API. The API has

# never been defined so this could cause backwards compatibility

# issues.

def getallmatchingheaders(self, name):

"""Find all header lines matching a given header name.

Look through the list of headers and find all lines matching a given

header name (and their continuation lines). A list of the lines is

returned, without interpretation. If the header does not occur, an

empty list is returned. If the header occurs multiple times, all

occurrences are returned. Case is not important in the header name.

"""

name = name.lower() + ':'

n = len(name)

lst = []

hit = 0

for line in self.keys():

if line[:n].lower() == name:

hit = 1

elif not line[:1].isspace():

hit = 0

if hit:

lst.append(line)

return lst

def parse_headers(fp, _class=HTTPMessage):

"""Parses only RFC2822 headers from a file pointer.

email Parser wants to see strings rather than bytes.

But a TextIOWrapper around self.rfile would buffer too many bytes

from the stream, bytes which we later need to read as bytes.

So we read the correct bytes here, as bytes, for email Parser

to parse.

"""

headers = []

while True:

line = fp.readline(_MAXLINE + 1)

if len(line) > _MAXLINE:

raise LineTooLong("header line")

headers.append(line)

if line in (b'\r\n', b'\n', b''):

break

hstring = b''.join(headers).decode('iso-8859-1')

return email.parser.Parser(_class=_class).parsestr(hstring)

_strict_sentinel = object()

class HTTPResponse(io.RawIOBase):

# See RFC 2616 sec 19.6 and RFC 1945 sec 6 for details.

# The bytes from the socket object are iso-8859-1 strings.

# See RFC 2616 sec 2.2 which notes an exception for MIME-encoded

# text following RFC 2047. The basic status line parsing only

# accepts iso-8859-1.

def __init__(self, sock, debuglevel=0, strict=_strict_sentinel, method=None, url=None):

# If the response includes a content-length header, we need to

# make sure that the client doesn't read more than the

# specified number of bytes. If it does, it will block until

# the server times out and closes the connection. This will

# happen if a self.fp.read() is done (without a size) whether

# self.fp is buffered or not. So, no self.fp.read() by

# clients unless they know what they are doing.

self.fp = sock.makefile("rb")

self.debuglevel = debuglevel

if strict is not _strict_sentinel:

warnings.warn("the 'strict' argument isn't supported anymore; "

"http.client now always assumes HTTP/1.x compliant servers.",

DeprecationWarning, 2)

self._method = method

# The HTTPResponse object is returned via urllib. The clients

# of http and urllib expect different attributes for the

# headers. headers is used here and supports urllib. msg is

# provided as a backwards compatibility layer for http

# clients.

self.headers = self.msg = None

# from the Status-Line of the response

self.version = _UNKNOWN # HTTP-Version

self.status = _UNKNOWN # Status-Code

self.reason = _UNKNOWN # Reason-Phrase

self.chunked = _UNKNOWN # is "chunked" being used?

self.chunk_left = _UNKNOWN # bytes left to read in current chunk

self.length = _UNKNOWN # number of bytes left in response

self.will_close = _UNKNOWN # conn will close at end of response

def _read_status(self):

line = str(self.fp.readline(_MAXLINE + 1), "iso-8859-1")

if len(line) > _MAXLINE:

raise LineTooLong("status line")

if self.debuglevel > 0:

print("reply:", repr(line))

if not line:

# Presumably, the server closed the connection before

# sending a valid response.

raise BadStatusLine(line)

try:

version, status, reason = line.split(None, 2)

except ValueError:

try:

version, status = line.split(None, 1)

reason = ""

except ValueError:

# empty version will cause next test to fail.

version = ""

if not version.startswith("HTTP/"):

self.close()

raise BadStatusLine(line)

# The status code is a three-digit number

try:

status = int(status)

if status < 100 or status > 999:

raise BadStatusLine(line)

except ValueError:

raise BadStatusLine(line)

return version, status, reason

def begin(self):

if self.headers is not None:

# we've already started reading the response

return

# read until we get a non-100 response

while True:

version, status, reason = self._read_status()

if status != CONTINUE:

break

# skip the header from the 100 response

while True:

skip = self.fp.readline(_MAXLINE + 1)

if len(skip) > _MAXLINE:

raise LineTooLong("header line")

skip = skip.strip()

if not skip:

break

if self.debuglevel > 0:

print("header:", skip)

self.code = self.status = status

self.reason = reason.strip()

if version in ("HTTP/1.0", "HTTP/0.9"):

# Some servers might still return "0.9", treat it as 1.0 anyway

self.version = 10

elif version.startswith("HTTP/1."):

self.version = 11 # use HTTP/1.1 code for HTTP/1.x where x>=1

else:

raise UnknownProtocol(version)

self.headers = self.msg = parse_headers(self.fp)

if self.debuglevel > 0:

for hdr in self.headers:

print("header:", hdr, end=" ")

# are we using the chunked-style of transfer encoding?

tr_enc = self.headers.get("transfer-encoding")

if tr_enc and tr_enc.lower() == "chunked":

self.chunked = True

self.chunk_left = None

else:

self.chunked = False

# will the connection close at the end of the response?

self.will_close = self._check_close()

# do we have a Content-Length?

# NOTE: RFC 2616, S4.4, #3 says we ignore this if tr_enc is "chunked"

self.length = None

length = self.headers.get("content-length")

# are we using the chunked-style of transfer encoding?

tr_enc = self.headers.get("transfer-encoding")

if length and not self.chunked:

try:

self.length = int(length)

except ValueError:

self.length = None

else:

if self.length < 0: # ignore nonsensical negative lengths

self.length = None

else:

self.length = None

# does the body have a fixed length? (of zero)

if (status == NO_CONTENT or status == NOT_MODIFIED or

100 <= status < 200 or # 1xx codes

self._method == "HEAD"):

self.length = 0

# if the connection remains open, and we aren't using chunked, and

# a content-length was not provided, then assume that the connection

# WILL close.

if (not self.will_close and

not self.chunked and

self.length is None):

self.will_close = True

def _check_close(self):

conn = self.headers.get("connection")

if self.version == 11:

# An HTTP/1.1 proxy is assumed to stay open unless

# explicitly closed.

conn = self.headers.get("connection")

if conn and "close" in conn.lower():

return True

return False

# Some HTTP/1.0 implementations have support for persistent

# connections, using rules different than HTTP/1.1.

# For older HTTP, Keep-Alive indicates persistent connection.

if self.headers.get("keep-alive"):

return False

# At least Akamai returns a "Connection: Keep-Alive" header,

# which was supposed to be sent by the client.

if conn and "keep-alive" in conn.lower():

return False

# Proxy-Connection is a netscape hack.

pconn = self.headers.get("proxy-connection")

if pconn and "keep-alive" in pconn.lower():

return False

# otherwise, assume it will close

return True

def close(self):

if self.fp:

self.fp.close()

self.fp = None

# These implementations are for the benefit of io.BufferedReader.

# XXX This class should probably be revised to act more like

# the "raw stream" that BufferedReader expects.

@property

def closed(self):

return self.isclosed()

def flush(self):

self.fp.flush()

def readable(self):

return True

# End of "raw stream" methods

def isclosed(self):

# NOTE: it is possible that we will not ever call self.close(). This

# case occurs when will_close is TRUE, length is None, and we

# read up to the last byte, but NOT past it.

#

# IMPLIES: if will_close is FALSE, then self.close() will ALWAYS be

# called, meaning self.isclosed() is meaningful.

return self.fp is None

def read(self, amt=None):

if self.fp is None:

return b""

if self._method == "HEAD":

self.close()

return b""

if amt is not None:

# Amount is given, so call base class version

# (which is implemented in terms of self.readinto)

return super(HTTPResponse, self).read(amt)

else:

# Amount is not given (unbounded read) so we must check self.length

# and self.chunked

if self.chunked:

return self._readall_chunked()

if self.length is None:

s = self.fp.read()

else:

s = self._safe_read(self.length)

self.length = 0

self.close() # we read everything

return s

def readinto(self, b):

if self.fp is None:

return 0

if self._method == "HEAD":

self.close()

return 0

if self.chunked:

return self._readinto_chunked(b)

if self.length is not None:

if len(b) > self.length:

# clip the read to the "end of response"

b = memoryview(b)[0:self.length]

# we do not use _safe_read() here because this may be a .will_close

# connection, and the user is reading more bytes than will be provided

# (for example, reading in 1k chunks)

n = self.fp.readinto(b)

if self.length is not None:

self.length -= n

if not self.length:

self.close()

else:

if not n:

self.close()

return n

def _read_next_chunk_size(self):

# Read the next chunk size from the file

line = self.fp.readline(_MAXLINE + 1)

if len(line) > _MAXLINE:

raise LineTooLong("chunk size")

i = line.find(b";")

if i >= 0:

line = line[:i] # strip chunk-extensions

try:

return int(line, 16)

except ValueError:

# close the connection as protocol synchronisation is

# probably lost

self.close()

raise

def _read_and_discard_trailer(self):

# read and discard trailer up to the CRLF terminator

### note: we shouldn't have any trailers!

while True:

line = self.fp.readline(_MAXLINE + 1)

if len(line) > _MAXLINE:

raise LineTooLong("trailer line")

if not line:

# a vanishingly small number of sites EOF without

# sending the trailer

break

if line in (b'\r\n', b'\n', b''):

break

def _readall_chunked(self):

assert self.chunked != _UNKNOWN

chunk_left = self.chunk_left

value = []

while True:

if chunk_left is None:

try:

chunk_left = self._read_next_chunk_size()

if chunk_left == 0:

break

except ValueError:

raise IncompleteRead(b''.join(value))

value.append(self._safe_read(chunk_left))

# we read the whole chunk, get another

self._safe_read(2) # toss the CRLF at the end of the chunk

chunk_left = None

self._read_and_discard_trailer()

# we read everything; close the "file"

self.close()

return b''.join(value)

def _readinto_chunked(self, b):

assert self.chunked != _UNKNOWN

chunk_left = self.chunk_left

total_bytes = 0

mvb = memoryview(b)

while True:

if chunk_left is None:

try:

chunk_left = self._read_next_chunk_size()

if chunk_left == 0:

break

except ValueError:

raise IncompleteRead(bytes(b[0:total_bytes]))

if len(mvb) < chunk_left:

n = self._safe_readinto(mvb)

self.chunk_left = chunk_left - n

return total_bytes + n

elif len(mvb) == chunk_left:

n = self._safe_readinto(mvb)

self._safe_read(2) # toss the CRLF at the end of the chunk

self.chunk_left = None

return total_bytes + n

else:

temp_mvb = mvb[0:chunk_left]

n = self._safe_readinto(temp_mvb)

mvb = mvb[n:]

total_bytes += n

# we read the whole chunk, get another

self._safe_read(2) # toss the CRLF at the end of the chunk

chunk_left = None

self._read_and_discard_trailer()

# we read everything; close the "file"

self.close()

return total_bytes

def _safe_read(self, amt):

"""Read the number of bytes requested, compensating for partial reads.

Normally, we have a blocking socket, but a read() can be interrupted

by a signal (resulting in a partial read).

Note that we cannot distinguish between EOF and an interrupt when zero

bytes have been read. IncompleteRead() will be raised in this

situation.

This function should be used when <amt> bytes "should" be present for

reading. If the bytes are truly not available (due to EOF), then the

IncompleteRead exception can be used to detect the problem.

"""

s = []

while amt > 0:

chunk = self.fp.read(min(amt, MAXAMOUNT))

if not chunk:

raise IncompleteRead(b''.join(s), amt)

s.append(chunk)

amt -= len(chunk)

return b"".join(s)

def _safe_readinto(self, b):

"""Same as _safe_read, but for reading into a buffer."""

total_bytes = 0

mvb = memoryview(b)

while total_bytes < len(b):

if MAXAMOUNT < len(mvb):

temp_mvb = mvb[0:MAXAMOUNT]

n = self.fp.readinto(temp_mvb)

else:

n = self.fp.readinto(mvb)

if not n:

raise IncompleteRead(bytes(mvb[0:total_bytes]), len(b))

mvb = mvb[n:]

total_bytes += n

return total_bytes

def fileno(self):

return self.fp.fileno()

def getheader(self, name, default=None):

if self.headers is None:

raise ResponseNotReady()

headers = self.headers.get_all(name) or default

if isinstance(headers, str) or not hasattr(headers, '__iter__'):

return headers

else:

return ', '.join(headers)

def getheaders(self):

"""Return list of (header, value) tuples."""

if self.headers is None:

raise ResponseNotReady()

return list(self.headers.items())

# We override IOBase.__iter__ so that it doesn't check for closed-ness

def __iter__(self):

return self

# For compatibility with old-style urllib responses.

def info(self):

return self.headers

def geturl(self):

return self.url

def getcode(self):

return self.status

class HTTPConnection:

_http_vsn = 11

_http_vsn_str = 'HTTP/1.1'

response_class = HTTPResponse

default_port = HTTP_PORT

auto_open = 1

debuglevel = 0

def __init__(self, host, port=None, strict=_strict_sentinel,

timeout=socket._GLOBAL_DEFAULT_TIMEOUT, source_address=None):

if strict is not _strict_sentinel:

warnings.warn("the 'strict' argument isn't supported anymore; "

"http.client now always assumes HTTP/1.x compliant servers.",

DeprecationWarning, 2)

self.timeout = timeout

self.source_address = source_address

self.sock = None

self._buffer = []

self.__response = None

self.__state = _CS_IDLE

self._method = None

self._tunnel_host = None

self._tunnel_port = None

self._tunnel_headers = {}

self._set_hostport(host, port)

def set_tunnel(self, host, port=None, headers=None):

""" Sets up the host and the port for the HTTP CONNECT Tunnelling.

The headers argument should be a mapping of extra HTTP headers

to send with the CONNECT request.

"""

self._tunnel_host = host

self._tunnel_port = port

if headers:

self._tunnel_headers = headers

else:

self._tunnel_headers.clear()

def _set_hostport(self, host, port):

if port is None:

i = host.rfind(':')

j = host.rfind(']') # ipv6 addresses have [...]

if i > j:

try:

port = int(host[i+1:])

except ValueError:

if host[i+1:] == "": # http://foo.com:/ == http://foo.com/

port = self.default_port

else:

raise InvalidURL("nonnumeric port: '%s'" % host[i+1:])

host = host[:i]

else:

port = self.default_port

if host and host[0] == '[' and host[-1] == ']':

host = host[1:-1]

self.host = host

self.port = port

def set_debuglevel(self, level):

self.debuglevel = level

def _tunnel(self):

self._set_hostport(self._tunnel_host, self._tunnel_port)

connect_str = "CONNECT %s:%d HTTP/1.0\r\n" % (self.host, self.port)

connect_bytes = connect_str.encode("ascii")

self.send(connect_bytes)

for header, value in self._tunnel_headers.items():

header_str = "%s: %s\r\n" % (header, value)

header_bytes = header_str.encode("latin-1")

self.send(header_bytes)

self.send(b'\r\n')

response = self.response_class(self.sock, method=self._method)

(version, code, message) = response._read_status()

if code != 200:

self.close()

raise socket.error("Tunnel connection failed: %d %s" % (code,

message.strip()))

while True:

line = response.fp.readline(_MAXLINE + 1)

if len(line) > _MAXLINE:

raise LineTooLong("header line")

if not line:

# for sites which EOF without sending a trailer

break

if line in (b'\r\n', b'\n', b''):

break

def connect(self):

"""Connect to the host and port specified in __init__."""

self.sock = socket.create_connection((self.host,self.port),

self.timeout, self.source_address)

if self._tunnel_host:

self._tunnel()

def close(self):

"""Close the connection to the HTTP server."""

if self.sock:

self.sock.close() # close it manually... there may be other refs

self.sock = None

if self.__response:

self.__response.close()

self.__response = None

self.__state = _CS_IDLE

def send(self, data):

"""Send `data' to the server.

``data`` can be a string object, a bytes object, an array object, a

file-like object that supports a .read() method, or an iterable object.

"""

if self.sock is None:

if self.auto_open:

self.connect()

else:

raise NotConnected()

if self.debuglevel > 0:

print("send:", repr(data))

blocksize = 8192

if hasattr(data, "read") :

if self.debuglevel > 0:

print("sendIng a read()able")

encode = False

try:

mode = data.mode

except AttributeError:

# io.BytesIO and other file-like objects don't have a `mode`

# attribute.

pass

else:

if "b" not in mode:

encode = True

if self.debuglevel > 0:

print("encoding file using iso-8859-1")

while 1:

datablock = data.read(blocksize)

if not datablock:

break

if encode:

datablock = datablock.encode("iso-8859-1")

self.sock.sendall(datablock)

try:

self.sock.sendall(data)

except TypeError:

if isinstance(data, collections.Iterable):

for d in data:

self.sock.sendall(d)

else:

raise TypeError("data should be a bytes-like object "

"or an iterable, got %r" % type(data))

def _output(self, s):

"""Add a line of output to the current request buffer.

Assumes that the line does *not* end with \\r\\n.

"""

self._buffer.append(s)

def _send_output(self, message_body=None):

"""Send the currently buffered request and clear the buffer.

Appends an extra \\r\\n to the buffer.

A message_body may be specified, to be appended to the request.

"""

self._buffer.extend((b"", b""))

msg = b"\r\n".join(self._buffer)

del self._buffer[:]

# If msg and message_body are sent in a single send() call,

# it will avoid performance problems caused by the interaction

# between delayed ack and the Nagle algorithm.

if isinstance(message_body, bytes):

msg += message_body

message_body = None

self.send(msg)

if message_body is not None:

# message_body was not a string (i.e. it is a file), and

# we must run the risk of Nagle.

self.send(message_body)

def putrequest(self, method, url, skip_host=0, skip_accept_encoding=0):

"""Send a request to the server.

`method' specifies an HTTP request method, e.g. 'GET'.

`url' specifies the object being requested, e.g. '/index.html'.

`skip_host' if True does not add automatically a 'Host:' header

`skip_accept_encoding' if True does not add automatically an

'Accept-Encoding:' header

"""

# if a prior response has been completed, then forget about it.

if self.__response and self.__response.isclosed():

self.__response = None

# in certain cases, we cannot issue another request on this connection.

# this occurs when:

# 1) we are in the process of sending a request. (_CS_REQ_STARTED)

# 2) a response to a previous request has signalled that it is going

# to close the connection upon completion.

# 3) the headers for the previous response have not been read, thus

# we cannot determine whether point (2) is true. (_CS_REQ_SENT)

#

# if there is no prior response, then we can request at will.

#

# if point (2) is true, then we will have passed the socket to the

# response (effectively meaning, "there is no prior response"), and

# will open a new one when a new request is made.

#

# Note: if a prior response exists, then we *can* start a new request.

# We are not allowed to begin fetching the response to this new

# request, however, until that prior response is complete.

#

if self.__state == _CS_IDLE:

self.__state = _CS_REQ_STARTED

else:

raise CannotSendRequest(self.__state)

# Save the method we use, we need it later in the response phase

self._method = method

if not url:

url = '/'

request = '%s %s %s' % (method, url, self._http_vsn_str)

# Non-ASCII characters should have been eliminated earlier

self._output(request.encode('ascii'))

if self._http_vsn == 11:

# Issue some standard headers for better HTTP/1.1 compliance

if not skip_host:

# this header is issued *only* for HTTP/1.1

# connections. more specifically, this means it is

# only issued when the client uses the new

# HTTPConnection() class. backwards-compat clients

# will be using HTTP/1.0 and those clients may be

# issuing this header themselves. we should NOT issue

# it twice; some web servers (such as Apache) barf

# when they see two Host: headers

# If we need a non-standard port,include it in the

# header. If the request is going through a proxy,

# but the host of the actual URL, not the host of the

# proxy.

netloc = ''

if url.startswith('http'):

nil, netloc, nil, nil, nil = urlsplit(url)

if netloc:

try:

netloc_enc = netloc.encode("ascii")

except UnicodeEncodeError:

netloc_enc = netloc.encode("idna")

self.putheader('Host', netloc_enc)

else:

try:

host_enc = self.host.encode("ascii")

except UnicodeEncodeError:

host_enc = self.host.encode("idna")

# As per RFC 273, IPv6 address should be wrapped with []

# when used as Host header

if self.host.find(':') >= 0:

host_enc = b'[' + host_enc + b']'

if self.port == self.default_port:

self.putheader('Host', host_enc)

else:

host_enc = host_enc.decode("ascii")

self.putheader('Host', "%s:%s" % (host_enc, self.port))

# note: we are assuming that clients will not attempt to set these

# headers since *this* library must deal with the

# consequences. this also means that when the supporting

# libraries are updated to recognize other forms, then this

# code should be changed (removed or updated).

# we only want a Content-Encoding of "identity" since we don't

# support encodings such as x-gzip or x-deflate.

if not skip_accept_encoding: