Revert removal of Http. Witness my indecisiveness.

ext/http-parser/README.md

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+HTTP Parser
+===========
+
+[![Build Status](https://travis-ci.org/joyent/http-parser.png?branch=master)](https://travis-ci.org/joyent/http-parser)
+
+This is a parser for HTTP messages written in C. It parses both requests and
+responses. The parser is designed to be used in performance HTTP
+applications. It does not make any syscalls nor allocations, it does not
+buffer data, it can be interrupted at anytime. Depending on your
+architecture, it only requires about 40 bytes of data per message
+stream (in a web server that is per connection).
+
+Features:
+
+  * No dependencies
+  * Handles persistent streams (keep-alive).
+  * Decodes chunked encoding.
+  * Upgrade support
+  * Defends against buffer overflow attacks.
+
+The parser extracts the following information from HTTP messages:
+
+  * Header fields and values
+  * Content-Length
+  * Request method
+  * Response status code
+  * Transfer-Encoding
+  * HTTP version
+  * Request URL
+  * Message body
+
+
+Usage
+-----
+
+One `http_parser` object is used per TCP connection. Initialize the struct
+using `http_parser_init()` and set the callbacks. That might look something
+like this for a request parser:
+
+    http_parser_settings settings;
+    settings.on_url = my_url_callback;
+    settings.on_header_field = my_header_field_callback;
+    /* ... */
+
+    http_parser *parser = malloc(sizeof(http_parser));
+    http_parser_init(parser, HTTP_REQUEST);
+    parser->data = my_socket;
+
+When data is received on the socket execute the parser and check for errors.
+
+    size_t len = 80*1024, nparsed;
+    char buf[len];
+    ssize_t recved;
+
+    recved = recv(fd, buf, len, 0);
+
+    if (recved < 0) {
+      /* Handle error. */
+    }
+
+    /* Start up / continue the parser.
+     * Note we pass recved==0 to signal that EOF has been recieved.
+     */
+    nparsed = http_parser_execute(parser, &settings, buf, recved);
+
+    if (parser->upgrade) {
+      /* handle new protocol */
+    } else if (nparsed != recved) {
+      /* Handle error. Usually just close the connection. */
+    }
+
+HTTP needs to know where the end of the stream is. For example, sometimes
+servers send responses without Content-Length and expect the client to
+consume input (for the body) until EOF. To tell http_parser about EOF, give
+`0` as the forth parameter to `http_parser_execute()`. Callbacks and errors
+can still be encountered during an EOF, so one must still be prepared
+to receive them.
+
+Scalar valued message information such as `status_code`, `method`, and the
+HTTP version are stored in the parser structure. This data is only
+temporally stored in `http_parser` and gets reset on each new message. If
+this information is needed later, copy it out of the structure during the
+`headers_complete` callback.
+
+The parser decodes the transfer-encoding for both requests and responses
+transparently. That is, a chunked encoding is decoded before being sent to
+the on_body callback.
+
+
+The Special Problem of Upgrade
+------------------------------
+
+HTTP supports upgrading the connection to a different protocol. An
+increasingly common example of this is the Web Socket protocol which sends
+a request like
+
+        GET /demo HTTP/1.1
+        Upgrade: WebSocket
+        Connection: Upgrade
+        Host: example.com
+        Origin: http://example.com
+        WebSocket-Protocol: sample
+
+followed by non-HTTP data.
+
+(See http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-75 for more
+information the Web Socket protocol.)
+
+To support this, the parser will treat this as a normal HTTP message without a
+body. Issuing both on_headers_complete and on_message_complete callbacks. However
+http_parser_execute() will stop parsing at the end of the headers and return.
+
+The user is expected to check if `parser->upgrade` has been set to 1 after
+`http_parser_execute()` returns. Non-HTTP data begins at the buffer supplied
+offset by the return value of `http_parser_execute()`.
+
+
+Callbacks
+---------
+
+During the `http_parser_execute()` call, the callbacks set in
+`http_parser_settings` will be executed. The parser maintains state and
+never looks behind, so buffering the data is not necessary. If you need to
+save certain data for later usage, you can do that from the callbacks.
+
+There are two types of callbacks:
+
+* notification `typedef int (*http_cb) (http_parser*);`
+    Callbacks: on_message_begin, on_headers_complete, on_message_complete.
+* data `typedef int (*http_data_cb) (http_parser*, const char *at, size_t length);`
+    Callbacks: (requests only) on_uri,
+               (common) on_header_field, on_header_value, on_body;
+
+Callbacks must return 0 on success. Returning a non-zero value indicates
+error to the parser, making it exit immediately.
+
+In case you parse HTTP message in chunks (i.e. `read()` request line
+from socket, parse, read half headers, parse, etc) your data callbacks
+may be called more than once. Http-parser guarantees that data pointer is only
+valid for the lifetime of callback. You can also `read()` into a heap allocated
+buffer to avoid copying memory around if this fits your application.
+
+Reading headers may be a tricky task if you read/parse headers partially.
+Basically, you need to remember whether last header callback was field or value
+and apply following logic:
+
+    (on_header_field and on_header_value shortened to on_h_*)
+     ------------------------ ------------ --------------------------------------------
+    | State (prev. callback) | Callback   | Description/action                         |
+     ------------------------ ------------ --------------------------------------------
+    | nothing (first call)   | on_h_field | Allocate new buffer and copy callback data |
+    |                        |            | into it                                    |
+     ------------------------ ------------ --------------------------------------------
+    | value                  | on_h_field | New header started.                        |
+    |                        |            | Copy current name,value buffers to headers |
+    |                        |            | list and allocate new buffer for new name  |
+     ------------------------ ------------ --------------------------------------------
+    | field                  | on_h_field | Previous name continues. Reallocate name   |
+    |                        |            | buffer and append callback data to it      |
+     ------------------------ ------------ --------------------------------------------
+    | field                  | on_h_value | Value for current header started. Allocate |
+    |                        |            | new buffer and copy callback data to it    |
+     ------------------------ ------------ --------------------------------------------
+    | value                  | on_h_value | Value continues. Reallocate value buffer   |
+    |                        |            | and append callback data to it             |
+     ------------------------ ------------ --------------------------------------------
+
+
+Parsing URLs
+------------
+
+A simplistic zero-copy URL parser is provided as `http_parser_parse_url()`.
+Users of this library may wish to use it to parse URLs constructed from
+consecutive `on_url` callbacks.
+
+See examples of reading in headers:
+
+* [partial example](http://gist.github.com/155877) in C
+* [from http-parser tests](http://github.com/joyent/http-parser/blob/37a0ff8/test.c#L403) in C
+* [from Node library](http://github.com/joyent/node/blob/842eaf4/src/http.js#L284) in Javascript