# `http.server` — HTTP 伺服器

原始碼：Lib/http/server.py

此模組定義了用於實作 HTTP 伺服器的類別。

警告

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

可用性: not WASI.

此模組在 WebAssembly 平台上不起作用或無法使用。更多資訊請參閱 WebAssembly 平台。

One class, `HTTPServer`, is a `socketserver.TCPServer` subclass. It creates and listens at the HTTP socket, dispatching the requests to a handler. Code to create and run the server looks like this:

    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)

  This class builds on the `TCPServer` class by storing the server address as instance variables named `server_name` and `server_port`. The server is accessible by the handler, typically through the handler's `server` instance variable.

class http.server.ThreadingHTTPServer(server_address, RequestHandlerClass)

  This class is identical to HTTPServer but uses threads to handle requests by using the `ThreadingMixIn`. This is useful to handle web browsers pre-opening sockets, on which `HTTPServer` would wait indefinitely.

  在 3.7 版被加入.

class http.server.HTTPSServer(server_address, RequestHandlerClass, bind_and_activate=True, *, certfile, keyfile=None, password=None, alpn_protocols=None)

  Subclass of `HTTPServer` with a wrapped socket using the `ssl` module. If the `ssl` module is not available, instantiating a `HTTPSServer` object fails with a `RuntimeError`.

  The certfile argument is the path to the SSL certificate chain file, and the keyfile is the path to file containing the private key.

  A password can be specified for files protected and wrapped with PKCS#8, but beware that this could possibly expose hardcoded passwords in clear.

  也參考

  See `ssl.SSLContext.load_cert_chain()` for additional information on the accepted values for certfile, keyfile and password.

  When specified, the alpn_protocols argument must be a sequence of strings specifying the "Application-Layer Protocol Negotiation" (ALPN) protocols supported by the server. ALPN allows the server and the client to negotiate the application protocol during the TLS handshake.

  By default, it is set to `["http/1.1"]`, meaning the server supports HTTP/1.1.

  在 3.14 版被加入.

class http.server.ThreadingHTTPSServer(server_address, RequestHandlerClass, bind_and_activate=True, *, certfile, keyfile=None, password=None, alpn_protocols=None)

  This class is identical to `HTTPSServer` but uses threads to handle requests by inheriting from `ThreadingMixIn`. This is analogous to `ThreadingHTTPServer` only using `HTTPSServer`.

  在 3.14 版被加入.

The `HTTPServer`, `ThreadingHTTPServer`, `HTTPSServer` and `ThreadingHTTPSServer` must be given a RequestHandlerClass on instantiation, of which this module provides three different variants:

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

  This class is used to handle the HTTP requests that arrive at the server. By itself, it cannot respond to any actual HTTP requests; it must be subclassed to handle each request method (e.g. GET or POST). `BaseHTTPRequestHandler` provides a number of class and instance variables, and methods for use by subclasses.

  The handler will parse the request and the headers, then call a method specific to the request type. The method name is constructed from the request. For example, for the request method `SPAM`, the `do_SPAM()` method will be called with no arguments. All of the relevant information is stored in instance variables of the handler. Subclasses should not need to override or extend the `__init__()` method.

  `BaseHTTPRequestHandler` 有以下實例變數：

  client_address

    Contains a tuple of the form `(host, port)` referring to the client's address.

  server

    Contains the server instance.

  close_connection

    Boolean that should be set before `handle_one_request()` returns, indicating if another request may be expected, or if the connection should be shut down.

  requestline

    Contains the string representation of the HTTP request line. The terminating CRLF is stripped. This attribute should be set by `handle_one_request()`. If no valid request line was processed, it should be set to the empty string.

  command

    Contains the command (request type). For example, `'GET'`.

  path

    Contains the request path. If query component of the URL is present, then `path` includes the query. Using the terminology of RFC 3986, `path` here includes `hier-part` and the `query`.

  request_version

    Contains the version string from the request. For example, `'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 5322 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.

    在 3.6 版的變更: This is an `io.BufferedIOBase` stream.

  `BaseHTTPRequestHandler` 擁有以下屬性：

  server_version

    Specifies the server software version. You may want to override this. The format is multiple whitespace-separated strings, where each string is of the form name[/version]. For example, `'BaseHTTP/0.2'`.

  sys_version

    Contains the Python system version, in a form usable by the `version_string` method and the `server_version` class variable. For example, `'Python/1.4'`.

  error_message_format

    Specifies a format string that should be used by `send_error()` method for building an error response to the client. The string is filled by default with variables from `responses` based on the status code that passed to `send_error()`.

  error_content_type

    Specifies the Content-Type HTTP header of error responses sent to the client. The default value is `'text/html'`.

  protocol_version

    Specifies the HTTP version to which the server is conformant. It is sent in responses to let the client know the server's communication capabilities for future requests. If set to `'HTTP/1.1'`, the server will permit HTTP persistent connections; however, your server must then include an accurate `Content-Length` header (using `send_header()`) in all of its responses to clients. For backwards compatibility, the setting defaults to `'HTTP/1.0'`.

  MessageClass

    Specifies an `email.message.Message`-like class to parse HTTP headers. Typically, this is not overridden, and it defaults to `http.client.HTTPMessage`.

  responses

    This attribute contains a mapping of error code integers to two-element tuples containing a short and long message. For example, `{code: (shortmessage, longmessage)}`. The shortmessage is usually used as the message key in an error response, and longmessage as the explain key. It is used by `send_response_only()` and `send_error()` methods.

  `BaseHTTPRequestHandler` 實例擁有以下方法：

  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 an HTTP/1.1 conformant 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`.

    在 3.2 版被加入.

  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`.

    在 3.4 版的變更: 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.

    在 3.3 版的變更: 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.

    在 3.2 版的變更: 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.

    在 3.2 版被加入.

  end_headers()

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

    在 3.2 版的變更: 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.

    在 3.3 版被加入.

  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.

    在 3.3 版的變更: 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.

  在 3.7 版的變更: 新增 directory 參數。

  在 3.9 版的變更: 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.

    在 3.9 版的變更: This dictionary is no longer filled with the default system mappings, but only contains overrides.

  `SimpleHTTPRequestHandler` 類別定義了以下方法：

  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 an `'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.

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

    在 3.7 版的變更: 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()

`SimpleHTTPRequestHandler` can also be subclassed to enhance behavior, such as using different index file names by overriding the class attribute `index_pages`.

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`.

  備註

  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.

  `CGIHTTPRequestHandler` 類別定義了以下資料成員：

  cgi_directories

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

  `CGIHTTPRequestHandler` 類別定義了以下方法：

  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.

  自從版本 3.13 後不推薦使用，將會自版本 3.15 中移除。: `CGIHTTPRequestHandler` is being removed in 3.15. CGI has not been considered a good way to do things for well over a decade. This code has been unmaintained for a while now and sees very little practical use. Retaining it could lead to further security considerations.

## 命令列介面

`http.server` can also be invoked directly using the `-m` switch of the interpreter. The following example illustrates how to serve files relative to the current directory:

    python -m http.server [OPTIONS] [port]

可接受以下選項：

port

  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

-b, --bind <address>

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

      python -m http.server --bind 127.0.0.1

  在 3.4 版被加入.

  在 3.8 版的變更: 於 `--bind` 選項中支援 IPv6。

-d, --directory <dir>

  Specifies a directory to which it should serve the files. By default, the server uses the current directory. For example, the following command uses a specific directory:

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

  在 3.7 版被加入.

-p, --protocol <version>

  Specifies the HTTP version to which the server is conformant. By default, the server is conformant to HTTP/1.0. For example, the following command runs an HTTP/1.1 conformant server:

      python -m http.server --protocol HTTP/1.1

  在 3.11 版被加入.

--cgi

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

      python -m http.server --cgi

  自從版本 3.13 後不推薦使用，將會自版本 3.15 中移除。: `http.server` command line `--cgi` support is being removed because `CGIHTTPRequestHandler` is being removed.

警告

`CGIHTTPRequestHandler` and the `--cgi` command-line option are not intended for use by untrusted clients and may be vulnerable to exploitation. Always use within a secure environment.

--tls-cert

  Specifies a TLS certificate chain for HTTPS connections:

      python -m http.server --tls-cert fullchain.pem

  在 3.14 版被加入.

--tls-key

  Specifies a private key file for HTTPS connections.

  This option requires `--tls-cert` to be specified.

  在 3.14 版被加入.

--tls-password-file

  Specifies the password file for password-protected private keys:

      python -m http.server \
             --tls-cert cert.pem \
             --tls-key key.pem \
             --tls-password-file password.txt

  This option requires --tls-cert` to be specified.

  在 3.14 版被加入.

## 安全性注意事項

`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.

在 3.12 版的變更: Control characters are scrubbed in stderr logs.