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# 21.12. `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 `http.client.``HTTPConnection`(host, port=None, [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.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)

  Changed in version 3.2: source_address was added.

  Changed in version 3.4: The strict parameter was removed. HTTP 0.9-style “Simple Responses” are not longer supported.

class `http.client.``HTTPSConnection`(host, port=None, key_file=None, cert_file=None, [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.

  key_file and cert_file are deprecated, please use `ssl.SSLContext.load_cert_chain()` instead, or let `ssl.create_default_context()` select the system’s trusted CA certificates for you. The check_hostname parameter is also deprecated; the `ssl.SSLContext.check_hostname` attribute of context should be used instead.

  Please read Security considerations for more information on best practices.

  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).

  Changed in version 3.4: The strict parameter was removed. HTTP 0.9-style “Simple Responses” are no longer supported.

  Changed in version 3.4.3: This class now performs all the necessary certificate and hostname checks by default. To revert to the previous, unverified, behavior `ssl._create_unverified_context()` can be passed to the context parameter.

class `http.client.``HTTPResponse`(sock, debuglevel=0, method=None, url=None)

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

  Changed in version 3.4: The strict parameter was removed. HTTP 0.9 style “Simple Responses” are no longer supported.

The following exceptions are raised as appropriate:

exception `http.client.``HTTPException`

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

exception `http.client.``NotConnected`

  A subclass of `HTTPException`.

exception `http.client.``InvalidURL`

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

exception `http.client.``UnknownProtocol`

  A subclass of `HTTPException`.

exception `http.client.``UnknownTransferEncoding`

  A subclass of `HTTPException`.

exception `http.client.``UnimplementedFileMode`

  A subclass of `HTTPException`.

exception `http.client.``IncompleteRead`

  A subclass of `HTTPException`.

exception `http.client.``ImproperConnectionState`

  A subclass of `HTTPException`.

exception `http.client.``CannotSendRequest`

  A subclass of `ImproperConnectionState`.

exception `http.client.``CannotSendHeader`

  A subclass of `ImproperConnectionState`.

exception `http.client.``ResponseNotReady`

  A subclass of `ImproperConnectionState`.

exception `http.client.``BadStatusLine`

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

exception `http.client.``LineTooLong`

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

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`).

`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'`.

See HTTP status codes for a list of HTTP status codes that are available in this module as constants.

## 21.12.1. 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 body is specified, the specified data is sent after the headers are finished. It may be a string, a bytes-like object, an open file object, or an iterable of bytes-like objects. If body is a string, it is encoded as ISO-8851-1, the default for HTTP. If it is a bytes-like object the bytes are sent as is. If it is a file object, the contents of the file is sent; this file object should support at least the `read()` method. If the file object has a `mode` attribute, the data returned by the `read()` method will be encoded as ISO-8851-1 unless the `mode` attribute contains the substring `b`, 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.

  If headers does not contain a Content-Length item, one is added automatically if possible. 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 bytes object, the Content-Length header is set to its length. If body is a file object and it works to call `fstat()` on the result of its `fileno()` method, then the Content-Length header is set to the `st_size` reported by the `fstat` call. Otherwise no Content-Length header is added.

  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.

## 21.12.2. 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.

## 21.12.3. 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/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

## 21.12.4. HTTPMessage Objects

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

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