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54 lines
1.9 KiB
54 lines
1.9 KiB
HTTP Parser
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===========
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This is a parser for HTTP messages written in C. It parses both requests
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and responses. The parser is designed to be used in performance HTTP
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applications. It does not make any allocations, it does not buffer data, and
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it can be interrupted at anytime. It only requires about 120 bytes of data
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per message stream (in a web server that is per connection).
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Usage
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-----
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One `http_parser` object is used per TCP connection. Initialize the struct
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using `http_parser_init()` and set the callbacks. That might look something
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like this:
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http_parser *parser = malloc(sizeof(http_parser));
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http_parser_init(parser, HTTP_REQUEST);
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parser->on_path = my_path_callback;
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parser->on_header_field = my_header_field_callback;
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parser->data = my_socket;
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When data is received on the socket execute the parser and check for errors.
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size_t len = 80*1024;
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char buf[len];
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ssize_t recved;
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recved = read(fd, buf, len);
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if (recved != 0) // handle error
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http_parser_execute(parser, buf, recved);
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if (http_parser_has_error(parser)) {
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// handle error. usually just close the connection
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}
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During the `http_parser_execute()` call, the callbacks set in `http_parser`
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will be executed. The parser maintains state and never looks behind, so
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buffering the data is not necessary. If you need to save certain data for
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later usage, you can do that from the callbacks. (You can also `read()` into
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a heap allocated buffer to avoid copying memory around if this fits your
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application.)
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The parser decodes the transfer-encoding for both requests and responses
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transparently. That is, a chunked encoding is decoded before being sent to
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the on_body callback.
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It does not decode the content-encoding (gzip). Not all HTTP applications
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need to inspect the body. Decoding gzip is non-neglagable amount of
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processing (and requires making allocations). HTTP proxies using this
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parser, for example, would not want such a feature.
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