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# 20.10. `http.client` — HTTP protocol client

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 the `socket` module was compiled with SSL support.

The module provides the following classes:

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

  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. When True, the optional parameter strict (which defaults to a false value) causes `BadStatusLine` to be raised if the status line can’t be parsed as a valid HTTP/1.0 or 1.1 status line. 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).

  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)

class `http.client.``HTTPSConnection`(host, port=None, key_file=None, cert_file=None, strict=None[, timeout])

  A subclass of `HTTPConnection` that uses SSL for communication with secure servers. Default port is `443`. key_file is the name of a PEM formatted file that contains your private key, and cert_file is a PEM formatted certificate chain file; both can be used for authenticating yourself against the server.

  Warning

  This does not do any verification of the server’s certificate.

class `http.client.``HTTPResponse`(sock, debuglevel=0, strict=0, method=None, url=None)
  Class whose instances are returned upon successful connection. Not instantiated directly by user.

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.

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
`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

`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'`.

## 20.10.1. 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 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 headers argument should be a mapping of extra HTTP headers to send with the request.

`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.``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`()
  Send a blank line to the server, signalling the end of the headers.

`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.

## 20.10.2. 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.``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.

## 20.10.3. 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()
    >>> 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 `HEAD` method. Note that `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({'spam': 1, 'eggs': 2, 'bacon': 0})
    >>> headers = {"Content-type": "application/x-www-form-urlencoded",
    ...            "Accept": "text/plain"}
    >>> conn = http.client.HTTPConnection("musi-cal.mojam.com:80")
    >>> conn.request("POST", "/cgi-bin/query", params, headers)
    >>> response = conn.getresponse()
    >>> print(response.status, response.reason)
    200 OK
    >>> data = response.read()
    >>> conn.close()

## 20.10.4. 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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