# `http.client` — HTTP protocol client

Source code: Lib/http/client.py

This module defines classes that 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.

See also

The Requests package is recommended for a higher-level HTTP client interface.

Note

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

Availability: not WASI.

This module does not work or is not available on WebAssembly. See WebAssembly platforms for more information.

The module provides the following classes:

class http.client.HTTPConnection(host, port=None, [timeout, ]source_address=None, blocksize=8192, max_response_headers=None)

  An `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. The optional max_response_headers parameter sets the maximum number of allowed response headers to help prevent denial-of-service attacks, otherwise the default value (100) 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.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 no longer supported.

  Changed in version 3.7: blocksize parameter was added.

  Changed in version 3.15: max_response_headers parameter was added.

class http.client.HTTPSConnection(host, port=None, *, [timeout, ]source_address=None, context=None, blocksize=8192, max_response_headers=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.

  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.

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

  Changed in version 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 `set_alpn_protocols()`.

  Changed in version 3.12: The deprecated key_file, cert_file and check_hostname parameters have been removed.

  Changed in version 3.15: max_response_headers parameter was added.

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.

This module provides the following function:

http.client.parse_headers(fp)

  Parse the headers from a file pointer fp representing a HTTP request/response. The file has to be a `BufferedIOBase` reader (i.e. not text) and must provide a valid RFC 5322 style header.

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

  Note

  `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 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.

exception http.client.RemoteDisconnected

  A subclass of `ConnectionResetError` and `BadStatusLine`. Raised by `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.

  Added in version 3.5: Previously, `BadStatusLine``('')` was raised.

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.

## HTTPConnection Objects

`HTTPConnection` instances have the following methods:

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 2616 §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 `str`, a bytes-like object, an open file object, or an iterable of `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 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 `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 Host header must be provided to conform with RFC 2616 §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 file, 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 `str` or bytes-like object that is not also a file as the body representation.

  Note

  Note that you must have read the whole response or call `close()` if `getresponse()` raised an non-`ConnectionError` exception before you can send a new request to the server.

  Changed in version 3.2: body can now be an iterable.

  Changed in version 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.

HTTPConnection.getresponse()

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

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

  Note that this does not apply to `OSError`s raised by the underlying socket. Instead the caller is responsible to call `close()` on the existing connection.

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.

  Added 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.

  As HTTP/1.1 is used for HTTP CONNECT tunnelling request, as per the RFC, 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 `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")

  Added in version 3.2.

  Changed in version 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.

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 `None`.

  Added in version 3.12.

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.

  Raises an auditing event `http.client.connect` with arguments `self`, `host`, `port`.

HTTPConnection.close()

  Close the connection to the server.

HTTPConnection.blocksize

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

  Added in version 3.7.

HTTPConnection.max_response_headers

  The maximum number of allowed response headers to help prevent denial-of-service attacks. By default, the maximum number of allowed headers is set to 100. The same limit applies to the trailer section of a chunked response.

  Added in version 3.15.

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(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.

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, *, 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 buffer interface the encoding will result in a single chunk. If message_body is a `collections.abc.Iterable`, each iteration of message_body will result in a chunk. If message_body is a 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.

  Changed in version 3.6: Added chunked encoding support and the encode_chunked parameter.

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.

  Raises an auditing event `http.client.send` with arguments `self`, `data`.

## 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.

Changed in version 3.5: The `io.BufferedIOBase` interface is now implemented and all of its reader operations are supported.

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.

  Added 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.url

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

HTTPResponse.headers

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

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.

HTTPResponse.geturl()

  Deprecated since version 3.9: Deprecated in favor of `url`.

HTTPResponse.info()

  Deprecated since version 3.9: Deprecated in favor of `headers`.

HTTPResponse.getcode()

  Deprecated since version 3.9: Deprecated in favor of `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 `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

class http.client.HTTPMessage(email.message.Message)

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