# `http.server` --- serveurs HTTP

Code source : Lib/http/server.py

Ce module définit des classes implémentant des serveurs HTTP.

Avertissement

`http.server` is not recommended for production. It only implements basic security checks.

Une des classes, `HTTPServer`, est une sous-classe de `socketserver.TCPServer`. Elle crée une interface de connexion (socket en anglais) avant de rester à l'écoute des messages reçus sur celle-ci, les répartissant à un gestionnaire d'évènements (handler en anglais). Le code pour créer et exécuter le serveur ressemble à ceci :

    def run(server_class=HTTPServer, handler_class=BaseHTTPRequestHandler):
        server_address = ('', 8000)
        httpd = server_class(server_address, handler_class)
        httpd.serve_forever()

class `http.server.``HTTPServer`(server_address, RequestHandlerClass)

  Cette classe hérite de la classe `TCPServer`. Ses instances contiennent l'adresse du serveur dans les variables d'instance `server_name` et `server_port`.Le serveur est accessible par le gestionnaire d'évènements, habituellement par le biais de sa variable d'instance `server`.

class `http.server.``ThreadingHTTPServer`(server_address, RequestHandlerClass)

  Cette classe est identique à HTTPServer mais utilise des fils d'exécution afin de gérer les requêtes, et ce, par le biais de `ThreadingMixIn`. Ceci est utile afin de gérer les pré-ouvertures des interfaces de connexion des navigateurs web, sur lesquelles `HTTPServer` attendrait de façon perpétuelle.

  Nouveau dans la version 3.7.

On doit passer un RequestHandlerClass lors de l'instanciation de `HTTPServer` et de `ThreadingHTTPServer`. Ce module fournit trois variantes différentes :

class `http.server.``BaseHTTPRequestHandler`(request, client_address, server)

  Cette classe est utilisée afin de gérer les requêtes HTTP arrivant au serveur. Elle ne peut pas répondre par elle-même à des requêtes HTTP ; cette méthode doit être surchargée dans les classes dérivées, par exemple GET ou POST. La classe `BaseHTTPRequestHandler` fournit plusieurs classes et variables d'instance, ainsi que des méthodes à utiliser par les sous-classes.

  Le gestionnaire d'évènements analysera la requête et les en-têtes avant d'appeler une méthode spécifique au type de requête. Le nom de la méthode est généré à partir de la requête. Par exemple, pour la méthode de requête `SPAM`, la méthode `do_SPAM()` sera appelée sans arguments. Toute l'information pertinente est sauvegardée dans les variables d'instance du gestionnaire d'évènements. Pour les sous-classes, il n'est pas nécessaire de surcharger ou de prolonger la méthode `__init__()`.

  `BaseHTTPRequestHandler` a les variables d'instances suivantes :

  `client_address`

    Contient un n-uplet de la forme `(host, port)`, faisant référence à l'adresse du client.

  `server`

    Contient l'instance du serveur.

  `close_connection`

    Booléen qui doit être défini avant que `handle_one_request()` ne termine son exécution, indiquant si on peut recevoir une autre requête ou si la connexion doit être fermée.

  `requestline`

    Contient la chaîne de caractères représentant la ligne de requête HTTP. La dénotation de fin de ligne CRLF est enlevée. Cet attribut doit être défini par `handle_one_request()`. Dans le cas où aucune ligne de requête valide n'a été traitée, il doit prendre la valeur de la chaîne de caractères vide.

  `command`

    Contient la commande (le type de requête). Par exemple, `'GET'`.

  `path`

    Contient le chemin de la requête. Si la composante de requête de l'URL est présente, alors `path` contient la requête. Selon la terminologie de RFC 3986, `path` inclut ici `hier-part` et la `query`.

  `request_version`

    Contient la version de la requête, en chaîne de caractères. Par exemple, `'HTTP/1.0'`.

  `headers`

    Holds an instance of the class specified by the `MessageClass` class variable. This instance parses and manages the headers in the HTTP request. The `parse_headers()` function from `http.client` is used to parse the headers and it requires that the HTTP request provide a valid RFC 2822 style header.

  `rfile`

    An `io.BufferedIOBase` input stream, ready to read from the start of the optional input data.

  `wfile`

    Contains the output stream for writing a response back to the client. Proper adherence to the HTTP protocol must be used when writing to this stream in order to achieve successful interoperation with HTTP clients.

    Modifié dans la version 3.6: This is an `io.BufferedIOBase` stream.

  `BaseHTTPRequestHandler` has the following attributes:

  `server_version`

    Précise la version du logiciel du serveur. Vous pouvez la modifier. Le format utilisé est constitué de plusieurs chaînes de caractères séparées par des caractères d'espacement, où chaque chaîne prend la forme nom[/version]. Par exemple, `'BaseHTTP/0.2'`.

  `sys_version`

    Contient la version système de Python, dans une forme pouvant être utilisée par la méthode `version_string` ainsi que par la variable de classe `server_version`. Par exemple, `'Python/1.4'`.

  `error_message_format`

    Définit une chaîne de caractères avec champs de formatage devant être utilisée par la méthode `send_error()` afin de construire une réponse d'erreur pour le client. Par défaut, la chaîne contient des variables provenant de l'attribut `responses` se basant sur le code de statut passé à `send_error()`.

  `error_content_type`

    Définit l'en-tête HTTP Content-Type des réponses d'erreur envoyées au client. La valeur par défaut est `'text/html'`.

  `protocol_version`

    Définit la version du protocole HTTP qui sera utilisée pour les réponses. Si définie comme `'HTTP/1.1.'`, le serveur permettra des connexions HTTP persistantes ; cependant, votre serveur doit alors inclure un en-tête `Content-Length` adéquat (en utilisant `send_header()`) dans toutes les réponses envoyées aux clients. Par souci de rétrocompatibilité, le paramètre prend `'HTTP/1.0'` comme valeur par défaut.

  `MessageClass`

    Définit une classe similaire à `email.message.Message` permettant l'analyse des en-têtes HTTP. Habituellement, cette valeur n'est pas modifiée, et prend par défaut la valeur de `http.client.HTTPMessage`.

  `responses`

    Cet attribut contient une table de correspondance entre des codes d'erreurs dénotés par des entiers et des n-uplets contenant un message court et un message long. Par exemple, `{code: (shortmessage, longmessage)}`. Habituellement, le message shortmessage correspond à la clé message d'une réponse d'erreur, alors que le message longmessage correspond à la clé explain de celle-ci. Il est utilisé par les méthodes `send_response_only()` et `send_error()`.

  Une instance de la classe `BaseHTTPRequestHandler` contient les méthodes suivantes :

  `handle`()

    Calls `handle_one_request()` once (or, if persistent connections are enabled, multiple times) to handle incoming HTTP requests. You should never need to override it; instead, implement appropriate `do_*()` methods.

  `handle_one_request`()

    This method will parse and dispatch the request to the appropriate `do_*()` method. You should never need to override it.

  `handle_expect_100`()

    When a HTTP/1.1 compliant server receives an `Expect: 100-continue` request header it responds back with a `100 Continue` followed by `200 OK` headers. This method can be overridden to raise an error if the server does not want the client to continue. For e.g. server can choose to send `417 Expectation Failed` as a response header and `return False`.

    Nouveau dans la version 3.2.

  `send_error`(code, message=None, explain=None)

    Sends and logs a complete error reply to the client. The numeric code specifies the HTTP error code, with message as an optional, short, human readable description of the error. The explain argument can be used to provide more detailed information about the error; it will be formatted using the `error_message_format` attribute and emitted, after a complete set of headers, as the response body. The `responses` attribute holds the default values for message and explain that will be used if no value is provided; for unknown codes the default value for both is the string `???`. The body will be empty if the method is HEAD or the response code is one of the following: `1xx`, `204 No Content`, `205 Reset Content`, `304 Not Modified`.

    Modifié dans la version 3.4: The error response includes a Content-Length header. Added the explain argument.

  `send_response`(code, message=None)

    Adds a response header to the headers buffer and logs the accepted request. The HTTP response line is written to the internal buffer, followed by Server and Date headers. The values for these two headers are picked up from the `version_string()` and `date_time_string()` methods, respectively. If the server does not intend to send any other headers using the `send_header()` method, then `send_response()` should be followed by an `end_headers()` call.

    Modifié dans la version 3.3: Headers are stored to an internal buffer and `end_headers()` needs to be called explicitly.

  `send_header`(keyword, value)

    Adds the HTTP header to an internal buffer which will be written to the output stream when either `end_headers()` or `flush_headers()` is invoked. keyword should specify the header keyword, with value specifying its value. Note that, after the send_header calls are done, `end_headers()` MUST BE called in order to complete the operation.

    Modifié dans la version 3.2: Headers are stored in an internal buffer.

  `send_response_only`(code, message=None)

    Sends the response header only, used for the purposes when `100 Continue` response is sent by the server to the client. The headers not buffered and sent directly the output stream.If the message is not specified, the HTTP message corresponding the response code is sent.

    Nouveau dans la version 3.2.

  `end_headers`()

    Adds a blank line (indicating the end of the HTTP headers in the response) to the headers buffer and calls `flush_headers()`.

    Modifié dans la version 3.2: The buffered headers are written to the output stream.

  `flush_headers`()

    Finally send the headers to the output stream and flush the internal headers buffer.

    Nouveau dans la version 3.3.

  `log_request`(code='-', size='-')

    Logs an accepted (successful) request. code should specify the numeric HTTP code associated with the response. If a size of the response is available, then it should be passed as the size parameter.

  `log_error`(...)

    Logs an error when a request cannot be fulfilled. By default, it passes the message to `log_message()`, so it takes the same arguments (format and additional values).

  `log_message`(format, ...)

    Logs an arbitrary message to `sys.stderr`. This is typically overridden to create custom error logging mechanisms. The format argument is a standard printf-style format string, where the additional arguments to `log_message()` are applied as inputs to the formatting. The client ip address and current date and time are prefixed to every message logged.

  `version_string`()

    Returns the server software's version string. This is a combination of the `server_version` and `sys_version` attributes.

  `date_time_string`(timestamp=None)

    Returns the date and time given by timestamp (which must be `None` or in the format returned by `time.time()`), formatted for a message header. If timestamp is omitted, it uses the current date and time.

    The result looks like `'Sun, 06 Nov 1994 08:49:37 GMT'`.

  `log_date_time_string`()

    Returns the current date and time, formatted for logging.

  `address_string`()

    Returns the client address.

    Modifié dans la version 3.3: Previously, a name lookup was performed. To avoid name resolution delays, it now always returns the IP address.

class `http.server.``SimpleHTTPRequestHandler`(request, client_address, server, directory=None)

  This class serves files from the directory directory and below, or the current directory if directory is not provided, directly mapping the directory structure to HTTP requests.

  Nouveau dans la version 3.7: The directory parameter.

  Modifié dans la version 3.9: The directory parameter accepts a path-like object.

  A lot of the work, such as parsing the request, is done by the base class `BaseHTTPRequestHandler`. This class implements the `do_GET()` and `do_HEAD()` functions.

  The following are defined as class-level attributes of `SimpleHTTPRequestHandler`:

  `server_version`

    This will be `"SimpleHTTP/" + __version__`, where `__version__` is defined at the module level.

  `extensions_map`

    A dictionary mapping suffixes into MIME types, contains custom overrides for the default system mappings. The mapping is used case-insensitively, and so should contain only lower-cased keys.

    Modifié dans la version 3.9: This dictionary is no longer filled with the default system mappings, but only contains overrides.

  The `SimpleHTTPRequestHandler` class defines the following methods:

  `do_HEAD`()

    This method serves the `'HEAD'` request type: it sends the headers it would send for the equivalent `GET` request. See the `do_GET()` method for a more complete explanation of the possible headers.

  `do_GET`()

    The request is mapped to a local file by interpreting the request as a path relative to the current working directory.

    If the request was mapped to a directory, the directory is checked for a file named `index.html` or `index.htm` (in that order). If found, the file's contents are returned; otherwise a directory listing is generated by calling the `list_directory()` method. This method uses `os.listdir()` to scan the directory, and returns a `404` error response if the `listdir()` fails.

    If the request was mapped to a file, it is opened. Any `OSError` exception in opening the requested file is mapped to a `404`, `'File not found'` error. If there was a `'If-Modified-Since'` header in the request, and the file was not modified after this time, a `304`, `'Not Modified'` response is sent. Otherwise, the content type is guessed by calling the `guess_type()` method, which in turn uses the extensions_map variable, and the file contents are returned.

    A `'Content-type:'` header with the guessed content type is output, followed by a `'Content-Length:'` header with the file's size and a `'Last-Modified:'` header with the file's modification time.

    Then follows a blank line signifying the end of the headers, and then the contents of the file are output. If the file's MIME type starts with `text/` the file is opened in text mode; otherwise binary mode is used.

    For example usage, see the implementation of the `test` function in Lib/http/server.py.

    Modifié dans la version 3.7: Support of the `'If-Modified-Since'` header.

The `SimpleHTTPRequestHandler` class can be used in the following manner in order to create a very basic webserver serving files relative to the current directory:

    import http.server
    import socketserver

    PORT = 8000

    Handler = http.server.SimpleHTTPRequestHandler

    with socketserver.TCPServer(("", PORT), Handler) as httpd:
        print("serving at port", PORT)
        httpd.serve_forever()

`http.server` can also be invoked directly using the `-m` switch of the interpreter. Similar to the previous example, this serves files relative to the current directory:

    python -m http.server

The server listens to port 8000 by default. The default can be overridden by passing the desired port number as an argument:

    python -m http.server 9000

By default, the server binds itself to all interfaces. The option `-b/--bind` specifies a specific address to which it should bind. Both IPv4 and IPv6 addresses are supported. For example, the following command causes the server to bind to localhost only:

    python -m http.server --bind 127.0.0.1

Nouveau dans la version 3.4: `--bind` argument was introduced.

Nouveau dans la version 3.8: `--bind` argument enhanced to support IPv6

By default, the server uses the current directory. The option `-d/--directory` specifies a directory to which it should serve the files. For example, the following command uses a specific directory:

    python -m http.server --directory /tmp/

Nouveau dans la version 3.7: `--directory` argument was introduced.

class `http.server.``CGIHTTPRequestHandler`(request, client_address, server)

  This class is used to serve either files or output of CGI scripts from the current directory and below. Note that mapping HTTP hierarchic structure to local directory structure is exactly as in `SimpleHTTPRequestHandler`.

  Note

  CGI scripts run by the `CGIHTTPRequestHandler` class cannot execute redirects (HTTP code 302), because code 200 (script output follows) is sent prior to execution of the CGI script. This pre-empts the status code.

  The class will however, run the CGI script, instead of serving it as a file, if it guesses it to be a CGI script. Only directory-based CGI are used --- the other common server configuration is to treat special extensions as denoting CGI scripts.

  The `do_GET()` and `do_HEAD()` functions are modified to run CGI scripts and serve the output, instead of serving files, if the request leads to somewhere below the `cgi_directories` path.

  The `CGIHTTPRequestHandler` defines the following data member:

  `cgi_directories`

    This defaults to `['/cgi-bin', '/htbin']` and describes directories to treat as containing CGI scripts.

  The `CGIHTTPRequestHandler` defines the following method:

  `do_POST`()

    This method serves the `'POST'` request type, only allowed for CGI scripts. Error 501, "Can only POST to CGI scripts", is output when trying to POST to a non-CGI url.

  Note that CGI scripts will be run with UID of user nobody, for security reasons. Problems with the CGI script will be translated to error 403.

`CGIHTTPRequestHandler` can be enabled in the command line by passing the `--cgi` option:

    python -m http.server --cgi

## Considérations de sécurité

`SimpleHTTPRequestHandler` will follow symbolic links when handling requests, this makes it possible for files outside of the specified directory to be served.

Earlier versions of Python did not scrub control characters from the log messages emitted to stderr from `python -m http.server` or the default `BaseHTTPRequestHandler` `.log_message` implementation. This could allow remote clients connecting to your server to send nefarious control codes to your terminal.

Nouveau dans la version 3.10.9: Control characters are scrubbed in stderr logs.