"http.client" --- cliente de protocolo HTTP
*******************************************

**Código-fonte:** 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.

Ver também:

  O pacote Requests é recomendado para uma interface alto nível de
  cliente HTTP.

Nota:

  Suporte HTTPS está disponível somente se Python foi compilado com
  suporte SSL (através do módulo "ssl").

Disponibilidade: não Emscripten, não WASI.

Este módulo não funciona ou não está disponível em plataformas
WebAssembly "wasm32-emscripten" e "wasm32-wasi". Veja Plataformas
WebAssembly para mais informações.

O módulo fornece as seguintes classes:

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

   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.

   Por exemplo, todas as seguintes chamadas criam instâncias que
   conectam ao servidor com o mesmo host e porta:

      >>> 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)

   Alterado na versão 3.2: *source_address* foi adicionado.

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

   Alterado na versão 3.7: O argumento *blocksize* foi adicionado.

class http.client.HTTPSConnection(host, port=None, key_file=None, cert_file=None, [timeout, ]source_address=None, *, context=None, check_hostname=None, blocksize=8192)

   Uma subclasse de "HTTPConnection" que utiliza SSL para comunicação
   com servidores seguros. A porta padrão é "443". Se *context* for
   especificado, ele deve ser uma instância de "ssl.SSLContext"
   descrevendo as várias opções do SSL.

   Por favor leia Considerações de segurança para mais informações
   sobre as melhores práticas.

   Alterado na versão 3.2: *source_address*, *context* e
   *check_hostname* foram adicionados.

   Alterado na versão 3.2: This class now supports HTTPS virtual hosts
   if possible (that is, if "ssl.HAS_SNI" is true).

   Alterado na versão 3.4: O argumento *strict* foi removido.
   "Respostas Simples" HTTP com o estilo 0.9 não são mais suportadas.

   Alterado na versão 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.

   Alterado na versão 3.8: Esta classe agora habilita TLS 1.3
   "ssl.SSLContext.post_handshake_auth" para o padrão *context* ou
   quanto *cert_file* é fornecido com um *context* personalizado.

   Alterado na versão 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()".

   Obsoleto desde a versão 3.6: *key_file* e *cert_file* estão
   descontinuados em favor de *context*. Por favor, em vez disso,
   utilize "ssl.SSLContext.load_cert_chain()" ou deixe
   "ssl.create_default_context()" selecionar os certificados CA
   confiáveis do sistema para você.O argumento *check_hostname* também
   está descontinuado; o atributo "ssl.SSLContext.check_hostname" de
   *context* deve ser usado em seu lugar.

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

   Classe em que instâncias são retornadas mediante de conexão bem-
   sucedida. Não é instanciável diretamente pelo usuário.

   Alterado na versão 3.4: O argumento *strict* foi removido.
   "Respostas Simples" HTTP com o estilo 0.9 não são mais suportadas.

Este módulo fornece a seguinte função:

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 2822** style header.

   Esta função retorna uma instância de "http.client.HTTPMessage" que
   armazena os campos do cabeçalho, mas não o payload (o mesmo que
   "HTTPResponse.msg" e "http.server.BaseHTTPRequestHandler.headers").
   Depois de retornar, o ponteiro de arquivo *fp* está pronto para ler
   o corpo da requisição HTTP.

   Nota:

     "parse_headers()" não analisa a linha inicial de uma mensagem
     HTTP; ele apenas analisa as linhas de "Name: value". O arquivo
     deve estar pronto para ler essas linhas de campo, então a
     primeira linha já deve ter sido consumida antes de chamar a
     função.

As seguintes exceções são levantadas conforme apropriado:

exception http.client.HTTPException

   A classe base das outras exceções neste módulo. É uma subclasse de
   "Exception".

exception http.client.NotConnected

   Uma subclasse de "HTTPException".

exception http.client.InvalidURL

   Uma subclasse de "HTTPException", levantada se uma porta é
   fornecida e esta é não-numérica ou vazia.

exception http.client.UnknownProtocol

   Uma subclasse de "HTTPException".

exception http.client.UnknownTransferEncoding

   Uma subclasse de "HTTPException".

exception http.client.UnimplementedFileMode

   Uma subclasse de "HTTPException".

exception http.client.IncompleteRead

   Uma subclasse de "HTTPException".

exception http.client.ImproperConnectionState

   Uma subclasse de "HTTPException".

exception http.client.CannotSendRequest

   Uma subclasse de "ImproperConnectionState".

exception http.client.CannotSendHeader

   Uma subclasse de "ImproperConnectionState".

exception http.client.ResponseNotReady

   Uma subclasse de "ImproperConnectionState".

exception http.client.BadStatusLine

   Uma subclasse de "HTTPException". Levantada se um servidor responde
   com um código de status HTTP que não é entendido.

exception http.client.LineTooLong

   Uma subclasse de "HTTPException". Levantada se uma linha
   excessivamente longa é recebida, do servidor, no protocolo HTTP.

exception http.client.RemoteDisconnected

   Uma subclasse de "ConnectionResetError" e "BadStatusLine".
   Levantada por "HTTPConnection.getresponse()" quando a tentativa de
   ler a resposta resulta na não leitura dos dados pela conexão,
   indicando que o fim remoto fechou a conexão.

   Novo na versão 3.5: Anteriormente, a exceção "BadStatusLine""('')"
   foi levantada.

As constantes definidas neste módulo são:

http.client.HTTP_PORT

   A porta padrão para o protocolo HTTP (sempre "80").

http.client.HTTPS_PORT

   A porta padrão para o protocolo HTTPS (sempre "443").

http.client.responses

   Este dicionário mapeia os códigos de status HTTP 1.1 para os nomes
   em W3C.

   Exemplo: "http.client.responses[http.client.NOT_FOUND]" é "'Not
   Found'".

Ver códigos de status HTTP para uma lista de códigos de status HTTP
que estão disponíveis neste módulo como constantes.


Objetos de HTTPConnection
=========================

Instâncias "HTTPConnection" contêm os seguintes métodos:

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).

   Se *body* é especificado, os dados especificados são mandados
   depois que os cabeçalhos estão prontos. Pode ser um "str", um
   *objeto bytes ou similar*, um *objeto arquivo* aberto, ou um
   iterável de "bytes". Se *body* é uma string, ele é codificado como
   ISO-8859-1, o padrão para HTTP. Se é um objeto bytes ou similar, os
   bytes são enviados como estão. Se é um *objeto arquivo*, o conteúdo
   do arquivo é enviado; este objeto arquivo deve oferecer suporte a
   pelo menos o método "read()". Se o objeto arquivo é uma instância
   de "io.TextIOBase", os dados retornados pelo método "read()" será
   codificado como ISO-8859-1, de outra forma os dados retornados por
   "read()" são enviados como estão. Se *body* é um iterável, os
   elementos do iterável são enviados até o iterável se esgotar.

   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

   Nota:

     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.

   Alterado na versão 3.2: *body* pode agora ser um iterável.

   Alterado na versão 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.

   Nota:

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

   Alterado na versão 3.5: Se uma "ConnectionError" ou subclasse for
   levantada, o objeto "HTTPConnection" estará pronto para se
   reconectar quando uma nova solicitação for enviada.

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.

   Novo na versão 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")

   Novo na versão 3.2.

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.

   Levanta um evento de auditoria "http.client.connect" com os
   argumentos "self", "host", "port".

HTTPConnection.close()

   Close the connection to the server.

HTTPConnection.blocksize

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

   Novo na versão 3.7.

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*.

   Nota:

     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.

   Alterado na versão 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.

   Levanta um evento de auditoria "http.client.send" com os argumentos
   "self", "data".


Objetos HTTPResponse
====================

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.

Alterado na versão 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.

   Novo na versão 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()

   Obsoleto desde a versão 3.9: Deprecated in favor of "url".

HTTPResponse.info()

   Obsoleto desde a versão 3.9: Deprecated in favor of "headers".

HTTPResponse.getcode()

   Obsoleto desde a versão 3.9: Deprecated in favor of "status".


Exemplos
========

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.
