:mod:`http.client` --- HTTP protocol client
===========================================

.. module:: http.client
   :synopsis: HTTP and HTTPS protocol client (requires sockets).

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

.. index::
   pair: HTTP; protocol
   single: HTTP; http.client (standard module)

.. index:: pair: module; urllib.request

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

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

.. seealso::

    The `Requests package <https://requests.readthedocs.io/en/latest/>`_
    is recommended for a higher-level HTTP client interface.

.. note::

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

.. include:: ../includes/wasm-notavail.rst

The module provides the following classes:


.. class:: HTTPConnection(host, port=None[, timeout], source_address=None, \
                          blocksize=8192)

   An :class:`HTTPConnection` instance represents one transaction with an HTTP
   server.  It should be instantiated by 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.
   The optional *blocksize* parameter sets the buffer size in bytes for
   sending a file-like message body.

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

      >>> h1 = http.client.HTTPConnection('www.python.org')
      >>> h2 = http.client.HTTPConnection('www.python.org:80')
      >>> h3 = http.client.HTTPConnection('www.python.org', 80)
      >>> h4 = http.client.HTTPConnection('www.python.org', 80, timeout=10)

   .. versionchanged:: 3.2
      *source_address* was added.

   .. versionchanged:: 3.4
      The  *strict* parameter was removed. HTTP 0.9-style "Simple Responses" are
      no longer supported.

   .. versionchanged:: 3.7
      *blocksize* parameter was added.


.. class:: HTTPSConnection(host, port=None, *[, timeout], \
                           source_address=None, context=None, \
                           blocksize=8192)

   A subclass of :class:`HTTPConnection` that uses SSL for communication with
   secure servers.  Default port is ``443``.  If *context* is specified, it
   must be a :class:`ssl.SSLContext` instance describing the various SSL
   options.

   Please read :ref:`ssl-security` for more information on best practices.

   .. versionchanged:: 3.2
      *source_address*, *context* and *check_hostname* were added.

   .. versionchanged:: 3.2
      This class now supports HTTPS virtual hosts if possible (that is,
      if :data:`ssl.HAS_SNI` is true).

   .. versionchanged:: 3.4
      The *strict* parameter was removed. HTTP 0.9-style "Simple Responses" are
      no longer supported.

   .. versionchanged:: 3.4.3
      This class now performs all the necessary certificate and hostname checks
      by default. To revert to the previous, unverified, behavior
      :func:`ssl._create_unverified_context` can be passed to the *context*
      parameter.

   .. versionchanged:: 3.8
      This class now enables TLS 1.3
      :attr:`ssl.SSLContext.post_handshake_auth` for the default *context* or
      when *cert_file* is passed with a custom *context*.

   .. versionchanged:: 3.10
      This class now sends an ALPN extension with protocol indicator
      ``http/1.1`` when no *context* is given. Custom *context* should set
      ALPN protocols with :meth:`~ssl.SSLContext.set_alpn_protocol`.

   .. versionchanged:: 3.12
      The deprecated *key_file*, *cert_file* and *check_hostname* parameters
      have been removed.


.. class:: HTTPResponse(sock, debuglevel=0, method=None, url=None)

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

   .. versionchanged:: 3.4
      The *strict* parameter was removed. HTTP 0.9 style "Simple Responses" are
      no longer supported.

This module provides the following function:

.. function:: parse_headers(fp)

   Parse the headers from a file pointer *fp* representing a HTTP
   request/response. The file has to be a :class:`BufferedIOBase` reader
   (i.e. not text) and must provide a valid :rfc:`2822` style header.

   This function returns an instance of :class:`http.client.HTTPMessage`
   that holds the header fields, but no payload
   (the same as :attr:`HTTPResponse.msg`
   and :attr:`http.server.BaseHTTPRequestHandler.headers`).
   After returning, the file pointer *fp* is ready to read the HTTP body.

   .. note::
      :meth:`parse_headers` does not parse the start-line of a HTTP message;
      it only parses the ``Name: value`` lines. The file has to be ready to
      read these field lines, so the first line should already be consumed
      before calling the function.

The following exceptions are raised as appropriate:


.. exception:: HTTPException

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


.. exception:: NotConnected

   A subclass of :exc:`HTTPException`.


.. exception:: InvalidURL

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


.. exception:: UnknownProtocol

   A subclass of :exc:`HTTPException`.


.. exception:: UnknownTransferEncoding

   A subclass of :exc:`HTTPException`.


.. exception:: UnimplementedFileMode

   A subclass of :exc:`HTTPException`.


.. exception:: IncompleteRead

   A subclass of :exc:`HTTPException`.


.. exception:: ImproperConnectionState

   A subclass of :exc:`HTTPException`.


.. exception:: CannotSendRequest

   A subclass of :exc:`ImproperConnectionState`.


.. exception:: CannotSendHeader

   A subclass of :exc:`ImproperConnectionState`.


.. exception:: ResponseNotReady

   A subclass of :exc:`ImproperConnectionState`.


.. exception:: BadStatusLine

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


.. exception:: LineTooLong

   A subclass of :exc:`HTTPException`.  Raised if an excessively long line
   is received in the HTTP protocol from the server.


.. exception:: RemoteDisconnected

   A subclass of :exc:`ConnectionResetError` and :exc:`BadStatusLine`.  Raised
   by :meth:`HTTPConnection.getresponse` when the attempt to read the response
   results in no data read from the connection, indicating that the remote end
   has closed the connection.

   .. versionadded:: 3.5
      Previously, :exc:`BadStatusLine`\ ``('')`` was raised.


The constants defined in this module are:

.. data:: HTTP_PORT

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

.. data:: HTTPS_PORT

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

.. data:: 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'``.

See :ref:`http-status-codes` for a list of HTTP status codes that are
available in this module as constants.


.. _httpconnection-objects:

HTTPConnection Objects
----------------------

:class:`HTTPConnection` instances have the following methods:


.. method:: HTTPConnection.request(method, url, body=None, headers={}, *, \
            encode_chunked=False)

   This will send a request to the server using the HTTP request
   method *method* and the request URI *url*. The provided *url* must be
   an absolute path to conform with :rfc:`RFC 2616 §5.1.2 <2616#section-5.1.2>`
   (unless connecting to an HTTP proxy server or using the ``OPTIONS`` or
   ``CONNECT`` methods).

   If *body* is specified, the specified data is sent after the headers are
   finished.  It may be a :class:`str`, a :term:`bytes-like object`, an
   open :term:`file object`, or an iterable of :class:`bytes`.  If *body*
   is a string, it is encoded as ISO-8859-1, the default for HTTP.  If it
   is a bytes-like object, the bytes are sent as is.  If it is a :term:`file
   object`, the contents of the file is sent; this file object should
   support at least the ``read()`` method.  If the file object is an
   instance of :class:`io.TextIOBase`, the data returned by the ``read()``
   method will be encoded as ISO-8859-1, otherwise the data returned by
   ``read()`` is sent as is.  If *body* is an iterable, the elements of the
   iterable are sent as is until the iterable is exhausted.

   The *headers* argument should be a mapping of extra HTTP headers to send
   with the request. A :rfc:`Host header <2616#section-14.23>`
   must be provided to conform with :rfc:`RFC 2616 §5.1.2 <2616#section-5.1.2>`
   (unless connecting to an HTTP proxy server or using the ``OPTIONS`` or
   ``CONNECT`` methods).

   If *headers* contains neither Content-Length nor Transfer-Encoding,
   but there is a request body, one of those
   header fields will be added automatically.  If
   *body* is ``None``, the Content-Length header is set to ``0`` for
   methods that expect a body (``PUT``, ``POST``, and ``PATCH``).  If
   *body* is a string or a bytes-like object that is not also a
   :term:`file <file object>`, the Content-Length header is
   set to its length.  Any other type of *body* (files
   and iterables in general) will be chunk-encoded, and the
   Transfer-Encoding header will automatically be set instead of
   Content-Length.

   The *encode_chunked* argument is only relevant if Transfer-Encoding is
   specified in *headers*.  If *encode_chunked* is ``False``, the
   HTTPConnection object assumes that all encoding is handled by the
   calling code.  If it is ``True``, the body will be chunk-encoded.

   For example, to perform a ``GET`` request to ``https://docs.python.org/3/``::

      >>> import http.client
      >>> host = "docs.python.org"
      >>> conn = http.client.HTTPSConnection(host)
      >>> conn.request("GET", "/3/", headers={"Host": host})
      >>> response = conn.getresponse()
      >>> print(response.status, response.reason)
      200 OK

   .. note::
      Chunked transfer encoding has been added to the HTTP protocol
      version 1.1.  Unless the HTTP server is known to handle HTTP 1.1,
      the caller must either specify the Content-Length, or must pass a
      :class:`str` or bytes-like object that is not also a file as the
      body representation.

   .. versionadded:: 3.2
      *body* can now be an iterable.

   .. versionchanged:: 3.6
      If neither Content-Length nor Transfer-Encoding are set in
      *headers*, file and iterable *body* objects are now chunk-encoded.
      The *encode_chunked* argument was added.
      No attempt is made to determine the Content-Length for file
      objects.

.. method:: HTTPConnection.getresponse()

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

   .. note::

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

   .. versionchanged:: 3.5
      If a :exc:`ConnectionError` or subclass is raised, the
      :class:`HTTPConnection` object will be ready to reconnect when
      a new request is sent.


.. method:: 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 :class:`HTTPResponse` objects that are created.

   .. versionadded:: 3.1


.. method:: 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.

   As HTTP/1.1 is used for HTTP CONNECT tunnelling request, `as per the RFC
   <https://datatracker.ietf.org/doc/html/rfc7231#section-4.3.6>`_, a HTTP ``Host:``
   header must be provided, matching the authority-form of the request target
   provided as the destination for the CONNECT request. If a HTTP ``Host:``
   header is not provided via the headers argument, one is generated and
   transmitted automatically.

   For example, to tunnel through a HTTPS proxy server running locally on port
   8080, we would pass the address of the proxy to the :class:`HTTPSConnection`
   constructor, and the address of the host that we eventually want to reach to
   the :meth:`~HTTPConnection.set_tunnel` method::

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

   .. versionadded:: 3.2

   .. versionchanged:: 3.12
      HTTP CONNECT tunnelling requests use protocol HTTP/1.1, upgraded from
      protocol HTTP/1.0. ``Host:`` HTTP headers are mandatory for HTTP/1.1, so
      one will be automatically generated and transmitted if not provided in
      the headers argument.


.. method:: HTTPConnection.get_proxy_response_headers()

   Returns a dictionary with the headers of the response received from
   the proxy server to the CONNECT request.

   If the CONNECT request was not sent, the method returns an empty dictionary.

   .. versionadded:: 3.12


.. method:: HTTPConnection.connect()

   Connect to the server specified when the object was created.  By default,
   this is called automatically when making a request if the client does not
   already have a connection.

   .. audit-event:: http.client.connect self,host,port http.client.HTTPConnection.connect


.. method:: HTTPConnection.close()

   Close the connection to the server.


.. attribute:: HTTPConnection.blocksize

   Buffer size in bytes for sending a file-like message body.

   .. versionadded:: 3.7


As an alternative to using the :meth:`request` method described above, you can
also send your request step by step, by using the four functions below.


.. method:: HTTPConnection.putrequest(method, url, 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 *method* string,
   the *url* 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.


.. method:: 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.


.. method:: HTTPConnection.endheaders(message_body=None, *, encode_chunked=False)

   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.

   If *encode_chunked* is ``True``, the result of each iteration of
   *message_body* will be chunk-encoded as specified in :rfc:`7230`,
   Section 3.3.1.  How the data is encoded is dependent on the type of
   *message_body*.  If *message_body* implements the :ref:`buffer interface
   <bufferobjects>` the encoding will result in a single chunk.
   If *message_body* is a :class:`collections.abc.Iterable`, each iteration
   of *message_body* will result in a chunk.  If *message_body* is a
   :term:`file object`, each call to ``.read()`` will result in a chunk.
   The method automatically signals the end of the chunk-encoded data
   immediately after *message_body*.

   .. note:: Due to the chunked encoding specification, empty chunks
      yielded by an iterator body will be ignored by the chunk-encoder.
      This is to avoid premature termination of the read of the request by
      the target server due to malformed encoding.

   .. versionadded:: 3.6
      Chunked encoding support.  The *encode_chunked* parameter was
      added.


.. method:: HTTPConnection.send(data)

   Send data to the server.  This should be used directly only after the
   :meth:`endheaders` method has been called and before :meth:`getresponse` is
   called.

   .. audit-event:: http.client.send self,data http.client.HTTPConnection.send


.. _httpresponse-objects:

HTTPResponse Objects
--------------------

An :class:`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.

.. versionchanged:: 3.5
   The :class:`io.BufferedIOBase` interface is now implemented and
   all of its reader operations are supported.


.. method:: HTTPResponse.read([amt])

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

.. method:: 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.

   .. versionadded:: 3.3

.. method:: 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.

.. method:: HTTPResponse.getheaders()

   Return a list of (header, value) tuples.

.. method:: HTTPResponse.fileno()

   Return the ``fileno`` of the underlying socket.

.. attribute:: HTTPResponse.msg

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

.. attribute:: HTTPResponse.version

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

.. attribute:: HTTPResponse.url

   URL of the resource retrieved, commonly used to determine if a redirect was followed.

.. attribute:: HTTPResponse.headers

   Headers of the response in the form of an :class:`email.message.EmailMessage` instance.

.. attribute:: HTTPResponse.status

   Status code returned by server.

.. attribute:: HTTPResponse.reason

   Reason phrase returned by server.

.. attribute:: HTTPResponse.debuglevel

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

.. attribute:: HTTPResponse.closed

   Is ``True`` if the stream is closed.

.. method:: HTTPResponse.geturl()

   .. deprecated:: 3.9
      Deprecated in favor of :attr:`~HTTPResponse.url`.

.. method:: HTTPResponse.info()

   .. deprecated:: 3.9
      Deprecated in favor of :attr:`~HTTPResponse.headers`.

.. method:: HTTPResponse.getcode()

   .. deprecated:: 3.9
      Deprecated in favor of :attr:`~HTTPResponse.status`.

Examples
--------

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

   >>> import http.client
   >>> conn = http.client.HTTPSConnection("www.python.org")
   >>> conn.request("GET", "/")
   >>> 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", "/")
   >>> r1 = conn.getresponse()
   >>> while chunk := r1.read(200):
   ...     print(repr(chunk))
   b'<!doctype html>\n<!--[if"...
   ...
   >>> # Example of an invalid request
   >>> conn = http.client.HTTPSConnection("docs.python.org")
   >>> 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.HTTPSConnection("www.python.org")
   >>> conn.request("HEAD", "/")
   >>> 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 uses the ``POST`` method::

   >>> 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="https://bugs.python.org/issue12524">https://bugs.python.org/issue12524</a>'
   >>> conn.close()

Client side HTTP ``PUT`` requests are very similar to ``POST`` requests. The
difference lies only on the server side where HTTP servers will allow resources to
be created via ``PUT`` requests. It should be noted that custom HTTP methods
are also handled in :class:`urllib.request.Request` by setting the appropriate
method attribute. Here is an example session that uses the ``PUT`` method::

    >>> # This creates an HTTP request
    >>> # with the content of BODY as the enclosed representation
    >>> # for the resource http://localhost:8080/file
    ...
    >>> 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:

HTTPMessage Objects
-------------------

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

.. XXX Define the methods that clients can depend upon between versions.
