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      1 /*
      2  * Copyright (c) 2000-2004 Niels Provos <provos (at) citi.umich.edu>
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. The name of the author may not be used to endorse or promote products
     14  *    derived from this software without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 #ifndef _EVHTTP_H_
     28 #define _EVHTTP_H_
     29 
     30 #include "event.h"
     31 
     32 #ifdef __cplusplus
     33 extern "C" {
     34 #endif
     35 
     36 #ifdef WIN32
     37 #define WIN32_LEAN_AND_MEAN
     38 #include <winsock2.h>
     39 #include <windows.h>
     40 #undef WIN32_LEAN_AND_MEAN
     41 #endif
     42 
     43 /** @file evhttp.h
     44  *
     45  * Basic support for HTTP serving.
     46  *
     47  * As libevent is a library for dealing with event notification and most
     48  * interesting applications are networked today, I have often found the
     49  * need to write HTTP code.  The following prototypes and definitions provide
     50  * an application with a minimal interface for making HTTP requests and for
     51  * creating a very simple HTTP server.
     52  */
     53 
     54 /* Response codes */
     55 #define HTTP_OK			200
     56 #define HTTP_NOCONTENT		204
     57 #define HTTP_MOVEPERM		301
     58 #define HTTP_MOVETEMP		302
     59 #define HTTP_NOTMODIFIED	304
     60 #define HTTP_BADREQUEST		400
     61 #define HTTP_NOTFOUND		404
     62 #define HTTP_SERVUNAVAIL	503
     63 
     64 struct evhttp;
     65 struct evhttp_request;
     66 struct evkeyvalq;
     67 
     68 /** Create a new HTTP server
     69  *
     70  * @param base (optional) the event base to receive the HTTP events
     71  * @return a pointer to a newly initialized evhttp server structure
     72  */
     73 struct evhttp *evhttp_new(struct event_base *base);
     74 
     75 /**
     76  * Binds an HTTP server on the specified address and port.
     77  *
     78  * Can be called multiple times to bind the same http server
     79  * to multiple different ports.
     80  *
     81  * @param http a pointer to an evhttp object
     82  * @param address a string containing the IP address to listen(2) on
     83  * @param port the port number to listen on
     84  * @return a newly allocated evhttp struct
     85  * @see evhttp_free()
     86  */
     87 int evhttp_bind_socket(struct evhttp *http, const char *address, u_short port);
     88 
     89 /**
     90  * Makes an HTTP server accept connections on the specified socket
     91  *
     92  * This may be useful to create a socket and then fork multiple instances
     93  * of an http server, or when a socket has been communicated via file
     94  * descriptor passing in situations where an http servers does not have
     95  * permissions to bind to a low-numbered port.
     96  *
     97  * Can be called multiple times to have the http server listen to
     98  * multiple different sockets.
     99  *
    100  * @param http a pointer to an evhttp object
    101  * @param fd a socket fd that is ready for accepting connections
    102  * @return 0 on success, -1 on failure.
    103  * @see evhttp_free(), evhttp_bind_socket()
    104  */
    105 int evhttp_accept_socket(struct evhttp *http, int fd);
    106 
    107 /**
    108  * Free the previously created HTTP server.
    109  *
    110  * Works only if no requests are currently being served.
    111  *
    112  * @param http the evhttp server object to be freed
    113  * @see evhttp_start()
    114  */
    115 void evhttp_free(struct evhttp* http);
    116 
    117 /** Set a callback for a specified URI */
    118 void evhttp_set_cb(struct evhttp *, const char *,
    119     void (*)(struct evhttp_request *, void *), void *);
    120 
    121 /** Removes the callback for a specified URI */
    122 int evhttp_del_cb(struct evhttp *, const char *);
    123 
    124 /** Set a callback for all requests that are not caught by specific callbacks
    125  */
    126 void evhttp_set_gencb(struct evhttp *,
    127     void (*)(struct evhttp_request *, void *), void *);
    128 
    129 /**
    130  * Set the timeout for an HTTP request.
    131  *
    132  * @param http an evhttp object
    133  * @param timeout_in_secs the timeout, in seconds
    134  */
    135 void evhttp_set_timeout(struct evhttp *, int timeout_in_secs);
    136 
    137 /* Request/Response functionality */
    138 
    139 /**
    140  * Send an HTML error message to the client.
    141  *
    142  * @param req a request object
    143  * @param error the HTTP error code
    144  * @param reason a brief explanation of the error
    145  */
    146 void evhttp_send_error(struct evhttp_request *req, int error,
    147     const char *reason);
    148 
    149 /**
    150  * Send an HTML reply to the client.
    151  *
    152  * @param req a request object
    153  * @param code the HTTP response code to send
    154  * @param reason a brief message to send with the response code
    155  * @param databuf the body of the response
    156  */
    157 void evhttp_send_reply(struct evhttp_request *req, int code,
    158     const char *reason, struct evbuffer *databuf);
    159 
    160 /* Low-level response interface, for streaming/chunked replies */
    161 void evhttp_send_reply_start(struct evhttp_request *, int, const char *);
    162 void evhttp_send_reply_chunk(struct evhttp_request *, struct evbuffer *);
    163 void evhttp_send_reply_end(struct evhttp_request *);
    164 
    165 /**
    166  * Start an HTTP server on the specified address and port
    167  *
    168  * DEPRECATED: it does not allow an event base to be specified
    169  *
    170  * @param address the address to which the HTTP server should be bound
    171  * @param port the port number on which the HTTP server should listen
    172  * @return an struct evhttp object
    173  */
    174 struct evhttp *evhttp_start(const char *address, u_short port);
    175 
    176 /*
    177  * Interfaces for making requests
    178  */
    179 enum evhttp_cmd_type { EVHTTP_REQ_GET, EVHTTP_REQ_POST, EVHTTP_REQ_HEAD };
    180 
    181 enum evhttp_request_kind { EVHTTP_REQUEST, EVHTTP_RESPONSE };
    182 
    183 /**
    184  * the request structure that a server receives.
    185  * WARNING: expect this structure to change.  I will try to provide
    186  * reasonable accessors.
    187  */
    188 struct evhttp_request {
    189 #if defined(TAILQ_ENTRY)
    190 	TAILQ_ENTRY(evhttp_request) next;
    191 #else
    192 struct {
    193 	struct evhttp_request *tqe_next;
    194 	struct evhttp_request **tqe_prev;
    195 }       next;
    196 #endif
    197 
    198 	/* the connection object that this request belongs to */
    199 	struct evhttp_connection *evcon;
    200 	int flags;
    201 #define EVHTTP_REQ_OWN_CONNECTION	0x0001
    202 #define EVHTTP_PROXY_REQUEST		0x0002
    203 
    204 	struct evkeyvalq *input_headers;
    205 	struct evkeyvalq *output_headers;
    206 
    207 	/* address of the remote host and the port connection came from */
    208 	char *remote_host;
    209 	u_short remote_port;
    210 
    211 	enum evhttp_request_kind kind;
    212 	enum evhttp_cmd_type type;
    213 
    214 	char *uri;			/* uri after HTTP request was parsed */
    215 
    216 	char major;			/* HTTP Major number */
    217 	char minor;			/* HTTP Minor number */
    218 
    219 	int response_code;		/* HTTP Response code */
    220 	char *response_code_line;	/* Readable response */
    221 
    222 	struct evbuffer *input_buffer;	/* read data */
    223 	ev_int64_t ntoread;
    224 	int chunked;
    225 
    226 	struct evbuffer *output_buffer;	/* outgoing post or data */
    227 
    228 	/* Callback */
    229 	void (*cb)(struct evhttp_request *, void *);
    230 	void *cb_arg;
    231 
    232 	/*
    233 	 * Chunked data callback - call for each completed chunk if
    234 	 * specified.  If not specified, all the data is delivered via
    235 	 * the regular callback.
    236 	 */
    237 	void (*chunk_cb)(struct evhttp_request *, void *);
    238 };
    239 
    240 /**
    241  * Creates a new request object that needs to be filled in with the request
    242  * parameters.  The callback is executed when the request completed or an
    243  * error occurred.
    244  */
    245 struct evhttp_request *evhttp_request_new(
    246 	void (*cb)(struct evhttp_request *, void *), void *arg);
    247 
    248 /** enable delivery of chunks to requestor */
    249 void evhttp_request_set_chunked_cb(struct evhttp_request *,
    250     void (*cb)(struct evhttp_request *, void *));
    251 
    252 /** Frees the request object and removes associated events. */
    253 void evhttp_request_free(struct evhttp_request *req);
    254 
    255 /**
    256  * A connection object that can be used to for making HTTP requests.  The
    257  * connection object tries to establish the connection when it is given an
    258  * http request object.
    259  */
    260 struct evhttp_connection *evhttp_connection_new(
    261 	const char *address, unsigned short port);
    262 
    263 /** Frees an http connection */
    264 void evhttp_connection_free(struct evhttp_connection *evcon);
    265 
    266 /** sets the ip address from which http connections are made */
    267 void evhttp_connection_set_local_address(struct evhttp_connection *evcon,
    268     const char *address);
    269 
    270 /** sets the local port from which http connections are made */
    271 void evhttp_connection_set_local_port(struct evhttp_connection *evcon,
    272     unsigned short port);
    273 
    274 /** Sets the timeout for events related to this connection */
    275 void evhttp_connection_set_timeout(struct evhttp_connection *evcon,
    276     int timeout_in_secs);
    277 
    278 /** Sets the retry limit for this connection - -1 repeats indefnitely */
    279 void evhttp_connection_set_retries(struct evhttp_connection *evcon,
    280     int retry_max);
    281 
    282 /** Set a callback for connection close. */
    283 void evhttp_connection_set_closecb(struct evhttp_connection *evcon,
    284     void (*)(struct evhttp_connection *, void *), void *);
    285 
    286 /**
    287  * Associates an event base with the connection - can only be called
    288  * on a freshly created connection object that has not been used yet.
    289  */
    290 void evhttp_connection_set_base(struct evhttp_connection *evcon,
    291     struct event_base *base);
    292 
    293 /** Get the remote address and port associated with this connection. */
    294 void evhttp_connection_get_peer(struct evhttp_connection *evcon,
    295     char **address, u_short *port);
    296 
    297 /** The connection gets ownership of the request */
    298 int evhttp_make_request(struct evhttp_connection *evcon,
    299     struct evhttp_request *req,
    300     enum evhttp_cmd_type type, const char *uri);
    301 
    302 const char *evhttp_request_uri(struct evhttp_request *req);
    303 
    304 /* Interfaces for dealing with HTTP headers */
    305 
    306 const char *evhttp_find_header(const struct evkeyvalq *, const char *);
    307 int evhttp_remove_header(struct evkeyvalq *, const char *);
    308 int evhttp_add_header(struct evkeyvalq *, const char *, const char *);
    309 void evhttp_clear_headers(struct evkeyvalq *);
    310 
    311 /* Miscellaneous utility functions */
    312 
    313 
    314 /**
    315   Helper function to encode a URI.
    316 
    317   The returned string must be freed by the caller.
    318 
    319   @param uri an unencoded URI
    320   @return a newly allocated URI-encoded string
    321  */
    322 char *evhttp_encode_uri(const char *uri);
    323 
    324 
    325 /**
    326   Helper function to decode a URI.
    327 
    328   The returned string must be freed by the caller.
    329 
    330   @param uri an encoded URI
    331   @return a newly allocated unencoded URI
    332  */
    333 char *evhttp_decode_uri(const char *uri);
    334 
    335 
    336 /**
    337  * Helper function to parse out arguments in a query.
    338  *
    339  * Parsing a uri like
    340  *
    341  *    http://foo.com/?q=test&s=some+thing
    342  *
    343  * will result in two entries in the key value queue.
    344 
    345  * The first entry is: key="q", value="test"
    346  * The second entry is: key="s", value="some thing"
    347  *
    348  * @param uri the request URI
    349  * @param headers the head of the evkeyval queue
    350  */
    351 void evhttp_parse_query(const char *uri, struct evkeyvalq *headers);
    352 
    353 
    354 /**
    355  * Escape HTML character entities in a string.
    356  *
    357  * Replaces <, >, ", ' and & with &lt;, &gt;, &quot;,
    358  * &#039; and &amp; correspondingly.
    359  *
    360  * The returned string needs to be freed by the caller.
    361  *
    362  * @param html an unescaped HTML string
    363  * @return an escaped HTML string
    364  */
    365 char *evhttp_htmlescape(const char *html);
    366 
    367 #ifdef __cplusplus
    368 }
    369 #endif
    370 
    371 #endif /* _EVHTTP_H_ */
    372