
"http.client" --- HTTP protocol client
**************************************

**Source code:** Lib/http/client.py

======================================================================

This module defines classes which implement the client side of the
HTTP and HTTPS protocols.  It is normally not used directly --- the
module "urllib.request" uses it to handle URLs that use HTTP and
HTTPS.

Note: HTTPS support is only available if Python was compiled with
  SSL support (through the "ssl" module).

The module provides the following classes:

class class http.client.HTTPConnection(host, port=None[, strict][, timeout],                        source_address=None)

   An "HTTPConnection" instance represents one transaction with an
   HTTP server.  It should be instantiated passing it a host and
   optional port number.  If no port number is passed, the port is
   extracted from the host string if it has the form "host:port", else
   the default HTTP port (80) is used.  If the optional *timeout*
   parameter is given, blocking operations (like connection attempts)
   will timeout after that many seconds (if it is not given, the
   global default timeout setting is used). The optional
   *source_address* parameter may be a tuple of a (host, port) to use
   as the source address the HTTP connection is made from.

   For example, the following calls all create instances that connect
   to the server at the same host and port:

      >>> h1 = http.client.HTTPConnection('www.cwi.nl')
      >>> h2 = http.client.HTTPConnection('www.cwi.nl:80')
      >>> h3 = http.client.HTTPConnection('www.cwi.nl', 80)
      >>> h3 = http.client.HTTPConnection('www.cwi.nl', 80, timeout=10)

   Changed in version 3.2: *source_address* was added.

   The *strict* parameter is deprecated.  HTTP 0.9-style "Simple
   Responses" are not supported anymore.Deprecated since version 3.2,
   will be removed in version 3.4.

class class http.client.HTTPSConnection(host, port=None, key_file=None,                         cert_file=None[, strict][, timeout],                         source_address=None, *, context=None,                         check_hostname=None)

   A subclass of "HTTPConnection" that uses SSL for communication with
   secure servers.  Default port is "443".  If *context* is specified,
   it must be a "ssl.SSLContext" instance describing the various SSL
   options.  If *context* is specified and has a "verify_mode" of
   either "CERT_OPTIONAL" or "CERT_REQUIRED", then by default *host*
   is matched against the host name(s) allowed by the server's
   certificate.  If you want to change that behaviour, you can
   explicitly set *check_hostname* to False.

   *key_file* and *cert_file* are deprecated, please use
   "ssl.SSLContext.load_cert_chain()" instead.

   If you access arbitrary hosts on the Internet, it is recommended to
   require certificate checking and feed the *context* with a set of
   trusted CA certificates:

      context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
      context.verify_mode = ssl.CERT_REQUIRED
      context.load_verify_locations('/etc/pki/tls/certs/ca-bundle.crt')
      h = client.HTTPSConnection('svn.python.org', 443, context=context)

   Changed in version 3.2: *source_address*, *context* and
   *check_hostname* were added.

   Changed in version 3.2: This class now supports HTTPS virtual hosts
   if possible (that is, if "ssl.HAS_SNI" is true).

   The *strict* parameter is deprecated.  HTTP 0.9-style "Simple
   Responses" are not supported anymore.Deprecated since version 3.2,
   will be removed in version 3.4.

class class http.client.HTTPResponse(sock, debuglevel=0[, strict], method=None, url=None)

   Class whose instances are returned upon successful connection.  Not
   instantiated directly by user.

   The *strict* parameter is deprecated.  HTTP 0.9-style "Simple
   Responses" are not supported anymore.Deprecated since version 3.2,
   will be removed in version 3.4.

The following exceptions are raised as appropriate:

exception exception http.client.HTTPException

   The base class of the other exceptions in this module.  It is a
   subclass of "Exception".

exception exception http.client.NotConnected

   A subclass of "HTTPException".

exception exception http.client.InvalidURL

   A subclass of "HTTPException", raised if a port is given and is
   either non-numeric or empty.

exception exception http.client.UnknownProtocol

   A subclass of "HTTPException".

exception exception http.client.UnknownTransferEncoding

   A subclass of "HTTPException".

exception exception http.client.UnimplementedFileMode

   A subclass of "HTTPException".

exception exception http.client.IncompleteRead

   A subclass of "HTTPException".

exception exception http.client.ImproperConnectionState

   A subclass of "HTTPException".

exception exception http.client.CannotSendRequest

   A subclass of "ImproperConnectionState".

exception exception http.client.CannotSendHeader

   A subclass of "ImproperConnectionState".

exception exception http.client.ResponseNotReady

   A subclass of "ImproperConnectionState".

exception exception http.client.BadStatusLine

   A subclass of "HTTPException".  Raised if a server responds with a
   HTTP status code that we don't understand.

The constants defined in this module are:

http.client.HTTP_PORT

   The default port for the HTTP protocol (always "80").

http.client.HTTPS_PORT

   The default port for the HTTPS protocol (always "443").

and also the following constants for integer status codes:

+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| Constant                                   | Value     | Definition                                                              |
+============================================+===========+=========================================================================+
| "CONTINUE"                                 | "100"     | HTTP/1.1, RFC 2616, Section 10.1.1                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "SWITCHING_PROTOCOLS"                      | "101"     | HTTP/1.1, RFC 2616, Section 10.1.2                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "PROCESSING"                               | "102"     | WEBDAV, RFC 2518, Section 10.1                                          |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "OK"                                       | "200"     | HTTP/1.1, RFC 2616, Section 10.2.1                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "CREATED"                                  | "201"     | HTTP/1.1, RFC 2616, Section 10.2.2                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "ACCEPTED"                                 | "202"     | HTTP/1.1, RFC 2616, Section 10.2.3                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "NON_AUTHORITATIVE_INFORMATION"            | "203"     | HTTP/1.1, RFC 2616, Section 10.2.4                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "NO_CONTENT"                               | "204"     | HTTP/1.1, RFC 2616, Section 10.2.5                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "RESET_CONTENT"                            | "205"     | HTTP/1.1, RFC 2616, Section 10.2.6                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "PARTIAL_CONTENT"                          | "206"     | HTTP/1.1, RFC 2616, Section 10.2.7                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "MULTI_STATUS"                             | "207"     | WEBDAV RFC 2518, Section 10.2                                           |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "IM_USED"                                  | "226"     | Delta encoding in HTTP, **RFC 3229**, Section 10.4.1                    |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "MULTIPLE_CHOICES"                         | "300"     | HTTP/1.1, RFC 2616, Section 10.3.1                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "MOVED_PERMANENTLY"                        | "301"     | HTTP/1.1, RFC 2616, Section 10.3.2                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "FOUND"                                    | "302"     | HTTP/1.1, RFC 2616, Section 10.3.3                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "SEE_OTHER"                                | "303"     | HTTP/1.1, RFC 2616, Section 10.3.4                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "NOT_MODIFIED"                             | "304"     | HTTP/1.1, RFC 2616, Section 10.3.5                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "USE_PROXY"                                | "305"     | HTTP/1.1, RFC 2616, Section 10.3.6                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "TEMPORARY_REDIRECT"                       | "307"     | HTTP/1.1, RFC 2616, Section 10.3.8                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "BAD_REQUEST"                              | "400"     | HTTP/1.1, RFC 2616, Section 10.4.1                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "UNAUTHORIZED"                             | "401"     | HTTP/1.1, RFC 2616, Section 10.4.2                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "PAYMENT_REQUIRED"                         | "402"     | HTTP/1.1, RFC 2616, Section 10.4.3                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "FORBIDDEN"                                | "403"     | HTTP/1.1, RFC 2616, Section 10.4.4                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "NOT_FOUND"                                | "404"     | HTTP/1.1, RFC 2616, Section 10.4.5                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "METHOD_NOT_ALLOWED"                       | "405"     | HTTP/1.1, RFC 2616, Section 10.4.6                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "NOT_ACCEPTABLE"                           | "406"     | HTTP/1.1, RFC 2616, Section 10.4.7                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "PROXY_AUTHENTICATION_REQUIRED"            | "407"     | HTTP/1.1, RFC 2616, Section 10.4.8                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "REQUEST_TIMEOUT"                          | "408"     | HTTP/1.1, RFC 2616, Section 10.4.9                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "CONFLICT"                                 | "409"     | HTTP/1.1, RFC 2616, Section 10.4.10                                     |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "GONE"                                     | "410"     | HTTP/1.1, RFC 2616, Section 10.4.11                                     |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "LENGTH_REQUIRED"                          | "411"     | HTTP/1.1, RFC 2616, Section 10.4.12                                     |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "PRECONDITION_FAILED"                      | "412"     | HTTP/1.1, RFC 2616, Section 10.4.13                                     |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "REQUEST_ENTITY_TOO_LARGE"                 | "413"     | HTTP/1.1, RFC 2616, Section 10.4.14                                     |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "REQUEST_URI_TOO_LONG"                     | "414"     | HTTP/1.1, RFC 2616, Section 10.4.15                                     |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "UNSUPPORTED_MEDIA_TYPE"                   | "415"     | HTTP/1.1, RFC 2616, Section 10.4.16                                     |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "REQUESTED_RANGE_NOT_SATISFIABLE"          | "416"     | HTTP/1.1, RFC 2616, Section 10.4.17                                     |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "EXPECTATION_FAILED"                       | "417"     | HTTP/1.1, RFC 2616, Section 10.4.18                                     |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "UNPROCESSABLE_ENTITY"                     | "422"     | WEBDAV, RFC 2518, Section 10.3                                          |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "LOCKED"                                   | "423"     | WEBDAV RFC 2518, Section 10.4                                           |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "FAILED_DEPENDENCY"                        | "424"     | WEBDAV, RFC 2518, Section 10.5                                          |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "UPGRADE_REQUIRED"                         | "426"     | HTTP Upgrade to TLS, **RFC 2817**, Section 6                            |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "PRECONDITION_REQUIRED"                    | "428"     | Additional HTTP Status Codes, **RFC 6585**, Section 3                   |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "TOO_MANY_REQUESTS"                        | "429"     | Additional HTTP Status Codes, **RFC 6585**, Section 4                   |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "REQUEST_HEADER_FIELDS_TOO_LARGE"          | "431"     | Additional HTTP Status Codes, **RFC 6585**, Section 5                   |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "INTERNAL_SERVER_ERROR"                    | "500"     | HTTP/1.1, RFC 2616, Section 10.5.1                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "NOT_IMPLEMENTED"                          | "501"     | HTTP/1.1, RFC 2616, Section 10.5.2                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "BAD_GATEWAY"                              | "502"     | HTTP/1.1 RFC 2616, Section 10.5.3                                       |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "SERVICE_UNAVAILABLE"                      | "503"     | HTTP/1.1, RFC 2616, Section 10.5.4                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "GATEWAY_TIMEOUT"                          | "504"     | HTTP/1.1 RFC 2616, Section 10.5.5                                       |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "HTTP_VERSION_NOT_SUPPORTED"               | "505"     | HTTP/1.1, RFC 2616, Section 10.5.6                                      |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "INSUFFICIENT_STORAGE"                     | "507"     | WEBDAV, RFC 2518, Section 10.6                                          |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "NOT_EXTENDED"                             | "510"     | An HTTP Extension Framework, **RFC 2774**, Section 7                    |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+
| "NETWORK_AUTHENTICATION_REQUIRED"          | "511"     | Additional HTTP Status Codes, **RFC 6585**, Section 6                   |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+

Changed in version 3.3: Added codes "428", "429", "431" and "511" from
**RFC 6585**.

http.client.responses

   This dictionary maps the HTTP 1.1 status codes to the W3C names.

   Example: "http.client.responses[http.client.NOT_FOUND]" is "'Not
   Found'".


HTTPConnection Objects
======================

"HTTPConnection" instances have the following methods:

HTTPConnection.request(method, url, body=None, headers={})

   This will send a request to the server using the HTTP request
   method *method* and the selector *url*.  If the *body* argument is
   present, it should be string or bytes object of data to send after
   the headers are finished.  Strings are encoded as ISO-8859-1, the
   default charset for HTTP.  To use other encodings, pass a bytes
   object.  The Content-Length header is set to the length of the
   string.

   The *body* may also be an open *file object*, in which case the
   contents of the file is sent; this file object should support
   "fileno()" and "read()" methods. The header Content-Length is
   automatically set to the length of the file as reported by stat.
   The *body* argument may also be an iterable and Content-Length
   header should be explicitly provided when the body is an iterable.

   The *headers* argument should be a mapping of extra HTTP headers to
   send with the request.

   New in version 3.2: *body* can now be an iterable.

HTTPConnection.getresponse()

   Should be called after a request is sent to get the response from
   the server. Returns an "HTTPResponse" instance.

   Note: Note that you must have read the whole response before you
     can send a new request to the server.

HTTPConnection.set_debuglevel(level)

   Set the debugging level.  The default debug level is "0", meaning
   no debugging output is printed.  Any value greater than "0" will
   cause all currently defined debug output to be printed to stdout.
   The "debuglevel" is passed to any new "HTTPResponse" objects that
   are created.

   New in version 3.1.

HTTPConnection.set_tunnel(host, port=None, headers=None)

   Set the host and the port for HTTP Connect Tunnelling. This allows
   running the connection through a proxy server.

   The host and port arguments specify the endpoint of the tunneled
   connection (i.e. the address included in the CONNECT request, *not*
   the address of the proxy server).

   The headers argument should be a mapping of extra HTTP headers to
   send with the CONNECT request.

   For example, to tunnel through a HTTPS proxy server running locally
   on port 8080, we would pass the address of the proxy to the
   "HTTPSConnection" constructor, and the address of the host that we
   eventually want to reach to the "set_tunnel()" method:

      >>> import http.client
      >>> conn = http.client.HTTPSConnection("localhost", 8080)
      >>> conn.set_tunnel("www.python.org")
      >>> conn.request("HEAD","/index.html")

   New in version 3.2.

HTTPConnection.connect()

   Connect to the server specified when the object was created.

HTTPConnection.close()

   Close the connection to the server.

As an alternative to using the "request()" method described above, you
can also send your request step by step, by using the four functions
below.

HTTPConnection.putrequest(request, selector, skip_host=False, skip_accept_encoding=False)

   This should be the first call after the connection to the server
   has been made. It sends a line to the server consisting of the
   *request* string, the *selector* string, and the HTTP version
   ("HTTP/1.1").  To disable automatic sending of "Host:" or "Accept-
   Encoding:" headers (for example to accept additional content
   encodings), specify *skip_host* or *skip_accept_encoding* with non-
   False values.

HTTPConnection.putheader(header, argument[, ...])

   Send an **RFC 822**-style header to the server.  It sends a line to
   the server consisting of the header, a colon and a space, and the
   first argument.  If more arguments are given, continuation lines
   are sent, each consisting of a tab and an argument.

HTTPConnection.endheaders(message_body=None)

   Send a blank line to the server, signalling the end of the headers.
   The optional *message_body* argument can be used to pass a message
   body associated with the request.  The message body will be sent in
   the same packet as the message headers if it is string, otherwise
   it is sent in a separate packet.

HTTPConnection.send(data)

   Send data to the server.  This should be used directly only after
   the "endheaders()" method has been called and before
   "getresponse()" is called.


HTTPResponse Objects
====================

An "HTTPResponse" instance wraps the HTTP response from the server.
It provides access to the request headers and the entity body.  The
response is an iterable object and can be used in a with statement.

HTTPResponse.read([amt])

   Reads and returns the response body, or up to the next *amt* bytes.

HTTPResponse.readinto(b)

   Reads up to the next len(b) bytes of the response body into the
   buffer *b*. Returns the number of bytes read.

   New in version 3.3.

HTTPResponse.getheader(name, default=None)

   Return the value of the header *name*, or *default* if there is no
   header matching *name*.  If there is more than one  header with the
   name *name*, return all of the values joined by ', '.  If 'default'
   is any iterable other than a single string, its elements are
   similarly returned joined by commas.

HTTPResponse.getheaders()

   Return a list of (header, value) tuples.

HTTPResponse.fileno()

   Return the "fileno" of the underlying socket.

HTTPResponse.msg

   A "http.client.HTTPMessage" instance containing the response
   headers.  "http.client.HTTPMessage" is a subclass of
   "email.message.Message".

HTTPResponse.version

   HTTP protocol version used by server.  10 for HTTP/1.0, 11 for
   HTTP/1.1.

HTTPResponse.status

   Status code returned by server.

HTTPResponse.reason

   Reason phrase returned by server.

HTTPResponse.debuglevel

   A debugging hook.  If "debuglevel" is greater than zero, messages
   will be printed to stdout as the response is read and parsed.

HTTPResponse.closed

   Is "True" if the stream is closed.


Examples
========

Here is an example session that uses the "GET" method:

   >>> import http.client
   >>> conn = http.client.HTTPConnection("www.python.org")
   >>> conn.request("GET", "/index.html")
   >>> r1 = conn.getresponse()
   >>> print(r1.status, r1.reason)
   200 OK
   >>> data1 = r1.read()  # This will return entire content.
   >>> # The following example demonstrates reading data in chunks.
   >>> conn.request("GET", "/index.html")
   >>> r1 = conn.getresponse()
   >>> while not r1.closed:
   ...     print(r1.read(200)) # 200 bytes
   b'<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"...
   ...
   >>> # Example of an invalid request
   >>> conn.request("GET", "/parrot.spam")
   >>> r2 = conn.getresponse()
   >>> print(r2.status, r2.reason)
   404 Not Found
   >>> data2 = r2.read()
   >>> conn.close()

Here is an example session that uses the "HEAD" method.  Note that the
"HEAD" method never returns any data.

   >>> import http.client
   >>> conn = http.client.HTTPConnection("www.python.org")
   >>> conn.request("HEAD","/index.html")
   >>> res = conn.getresponse()
   >>> print(res.status, res.reason)
   200 OK
   >>> data = res.read()
   >>> print(len(data))
   0
   >>> data == b''
   True

Here is an example session that shows how to "POST" requests:

   >>> import http.client, urllib.parse
   >>> params = urllib.parse.urlencode({'@number': 12524, '@type': 'issue', '@action': 'show'})
   >>> headers = {"Content-type": "application/x-www-form-urlencoded",
   ...            "Accept": "text/plain"}
   >>> conn = http.client.HTTPConnection("bugs.python.org")
   >>> conn.request("POST", "", params, headers)
   >>> response = conn.getresponse()
   >>> print(response.status, response.reason)
   302 Found
   >>> data = response.read()
   >>> data
   b'Redirecting to <a href="http://bugs.python.org/issue12524">http://bugs.python.org/issue12524</a>'
   >>> conn.close()

Client side "HTTP PUT" requests are very similar to "POST" requests.
The difference lies only the server side where HTTP server will allow
resources to be created via "PUT" request. It should be noted that
custom HTTP methods +are also handled in "urllib.request.Request" by
sending the appropriate +method attribute.Here is an example session
that shows how to do "PUT" request using http.client:

   >>> # This creates an HTTP message
   >>> # with the content of BODY as the enclosed representation
   >>> # for the resource http://localhost:8080/foobar
   ...
   >>> import http.client
   >>> BODY = "***filecontents***"
   >>> conn = http.client.HTTPConnection("localhost", 8080)
   >>> conn.request("PUT", "/file", BODY)
   >>> response = conn.getresponse()
   >>> print(response.status, response.reason)
   200, OK


HTTPMessage Objects
===================

An "http.client.HTTPMessage" instance holds the headers from an HTTP
response.  It is implemented using the "email.message.Message" class.
