`http.server` --- serveurs HTTP¶

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.

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