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.


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[, 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.

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

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
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).

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

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.

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

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:


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


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
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
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
EXPECTATION_FAILED 417 HTTP/1.1, RFC 2616, Section 10.4.18
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
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.


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

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

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 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.


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


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


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.


Connect to the server specified when the object was created.


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.


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.


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.


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


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.


Return a list of (header, value) tuples.


Return the fileno of the underlying socket.


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


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


Status code returned by server.


Reason phrase returned by server.


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


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))
>>> data == b''

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

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.