1 /*	$NetBSD: http.h,v 1.1.1.2 2015/01/29 06:38:28 spz Exp $	*/
2 /*	$NetBSD: http.h,v 1.1.1.2 2015/01/29 06:38:28 spz Exp $	*/
3 /*
4  * Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu>
5  * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. The name of the author may not be used to endorse or promote products
16  *    derived from this software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28  */
29 #ifndef _EVENT2_HTTP_H_
30 #define _EVENT2_HTTP_H_
31 
32 /* For int types. */
33 #include <event2/util.h>
34 
35 #ifdef __cplusplus
36 extern "C" {
37 #endif
38 
39 /* In case we haven't included the right headers yet. */
40 struct evbuffer;
41 struct event_base;
42 
43 /** @file event2/http.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	/**< request completed ok */
56 #define HTTP_NOCONTENT		204	/**< request does not have content */
57 #define HTTP_MOVEPERM		301	/**< the uri moved permanently */
58 #define HTTP_MOVETEMP		302	/**< the uri moved temporarily */
59 #define HTTP_NOTMODIFIED	304	/**< page was not modified from last */
60 #define HTTP_BADREQUEST		400	/**< invalid http request was made */
61 #define HTTP_NOTFOUND		404	/**< could not find content for uri */
62 #define HTTP_BADMETHOD		405 	/**< method not allowed for this uri */
63 #define HTTP_ENTITYTOOLARGE	413	/**<  */
64 #define HTTP_EXPECTATIONFAILED	417	/**< we can't handle this expectation */
65 #define HTTP_INTERNAL           500     /**< internal error */
66 #define HTTP_NOTIMPLEMENTED     501     /**< not implemented */
67 #define HTTP_SERVUNAVAIL	503	/**< the server is not available */
68 
69 struct evhttp;
70 struct evhttp_request;
71 struct evkeyvalq;
72 struct evhttp_bound_socket;
73 struct evconnlistener;
74 
75 /**
76  * Create a new HTTP server.
77  *
78  * @param base (optional) the event base to receive the HTTP events
79  * @return a pointer to a newly initialized evhttp server structure
80  * @see evhttp_free()
81  */
82 struct evhttp *evhttp_new(struct event_base *base);
83 
84 /**
85  * Binds an HTTP server on the specified address and port.
86  *
87  * Can be called multiple times to bind the same http server
88  * to multiple different ports.
89  *
90  * @param http a pointer to an evhttp object
91  * @param address a string containing the IP address to listen(2) on
92  * @param port the port number to listen on
93  * @return 0 on success, -1 on failure.
94  * @see evhttp_accept_socket()
95  */
96 int evhttp_bind_socket(struct evhttp *http, const char *address, ev_uint16_t port);
97 
98 /**
99  * Like evhttp_bind_socket(), but returns a handle for referencing the socket.
100  *
101  * The returned pointer is not valid after \a http is freed.
102  *
103  * @param http a pointer to an evhttp object
104  * @param address a string containing the IP address to listen(2) on
105  * @param port the port number to listen on
106  * @return Handle for the socket on success, NULL on failure.
107  * @see evhttp_bind_socket(), evhttp_del_accept_socket()
108  */
109 struct evhttp_bound_socket *evhttp_bind_socket_with_handle(struct evhttp *http, const char *address, ev_uint16_t port);
110 
111 /**
112  * Makes an HTTP server accept connections on the specified socket.
113  *
114  * This may be useful to create a socket and then fork multiple instances
115  * of an http server, or when a socket has been communicated via file
116  * descriptor passing in situations where an http servers does not have
117  * permissions to bind to a low-numbered port.
118  *
119  * Can be called multiple times to have the http server listen to
120  * multiple different sockets.
121  *
122  * @param http a pointer to an evhttp object
123  * @param fd a socket fd that is ready for accepting connections
124  * @return 0 on success, -1 on failure.
125  * @see evhttp_bind_socket()
126  */
127 int evhttp_accept_socket(struct evhttp *http, evutil_socket_t fd);
128 
129 /**
130  * Like evhttp_accept_socket(), but returns a handle for referencing the socket.
131  *
132  * The returned pointer is not valid after \a http is freed.
133  *
134  * @param http a pointer to an evhttp object
135  * @param fd a socket fd that is ready for accepting connections
136  * @return Handle for the socket on success, NULL on failure.
137  * @see evhttp_accept_socket(), evhttp_del_accept_socket()
138  */
139 struct evhttp_bound_socket *evhttp_accept_socket_with_handle(struct evhttp *http, evutil_socket_t fd);
140 
141 /**
142  * The most low-level evhttp_bind/accept method: takes an evconnlistener, and
143  * returns an evhttp_bound_socket.  The listener will be freed when the bound
144  * socket is freed.
145  */
146 struct evhttp_bound_socket *evhttp_bind_listener(struct evhttp *http, struct evconnlistener *listener);
147 
148 /**
149  * Return the listener used to implement a bound socket.
150  */
151 struct evconnlistener *evhttp_bound_socket_get_listener(struct evhttp_bound_socket *bound);
152 
153 /**
154  * Makes an HTTP server stop accepting connections on the specified socket
155  *
156  * This may be useful when a socket has been sent via file descriptor passing
157  * and is no longer needed by the current process.
158  *
159  * If you created this bound socket with evhttp_bind_socket_with_handle or
160  * evhttp_accept_socket_with_handle, this function closes the fd you provided.
161  * If you created this bound socket with evhttp_bind_listener, this function
162  * frees the listener you provided.
163  *
164  * \a bound_socket is an invalid pointer after this call returns.
165  *
166  * @param http a pointer to an evhttp object
167  * @param bound_socket a handle returned by evhttp_{bind,accept}_socket_with_handle
168  * @see evhttp_bind_socket_with_handle(), evhttp_accept_socket_with_handle()
169  */
170 void evhttp_del_accept_socket(struct evhttp *http, struct evhttp_bound_socket *bound_socket);
171 
172 /**
173  * Get the raw file descriptor referenced by an evhttp_bound_socket.
174  *
175  * @param bound_socket a handle returned by evhttp_{bind,accept}_socket_with_handle
176  * @return the file descriptor used by the bound socket
177  * @see evhttp_bind_socket_with_handle(), evhttp_accept_socket_with_handle()
178  */
179 evutil_socket_t evhttp_bound_socket_get_fd(struct evhttp_bound_socket *bound_socket);
180 
181 /**
182  * Free the previously created HTTP server.
183  *
184  * Works only if no requests are currently being served.
185  *
186  * @param http the evhttp server object to be freed
187  * @see evhttp_start()
188  */
189 void evhttp_free(struct evhttp* http);
190 
191 /** XXX Document. */
192 void evhttp_set_max_headers_size(struct evhttp* http, ev_ssize_t max_headers_size);
193 /** XXX Document. */
194 void evhttp_set_max_body_size(struct evhttp* http, ev_ssize_t max_body_size);
195 
196 /**
197   Sets the what HTTP methods are supported in requests accepted by this
198   server, and passed to user callbacks.
199 
200   If not supported they will generate a "405 Method not allowed" response.
201 
202   By default this includes the following methods: GET, POST, HEAD, PUT, DELETE
203 
204   @param http the http server on which to set the methods
205   @param methods bit mask constructed from evhttp_cmd_type values
206 */
207 void evhttp_set_allowed_methods(struct evhttp* http, ev_uint16_t methods);
208 
209 /**
210    Set a callback for a specified URI
211 
212    @param http the http sever on which to set the callback
213    @param path the path for which to invoke the callback
214    @param cb the callback function that gets invoked on requesting path
215    @param cb_arg an additional context argument for the callback
216    @return 0 on success, -1 if the callback existed already, -2 on failure
217 */
218 int evhttp_set_cb(struct evhttp *http, const char *path,
219     void (*cb)(struct evhttp_request *, void *), void *cb_arg);
220 
221 /** Removes the callback for a specified URI */
222 int evhttp_del_cb(struct evhttp *, const char *);
223 
224 /**
225     Set a callback for all requests that are not caught by specific callbacks
226 
227     Invokes the specified callback for all requests that do not match any of
228     the previously specified request paths.  This is catchall for requests not
229     specifically configured with evhttp_set_cb().
230 
231     @param http the evhttp server object for which to set the callback
232     @param cb the callback to invoke for any unmatched requests
233     @param arg an context argument for the callback
234 */
235 void evhttp_set_gencb(struct evhttp *http,
236     void (*cb)(struct evhttp_request *, void *), void *arg);
237 
238 /**
239    Adds a virtual host to the http server.
240 
241    A virtual host is a newly initialized evhttp object that has request
242    callbacks set on it via evhttp_set_cb() or evhttp_set_gencb().  It
243    most not have any listing sockets associated with it.
244 
245    If the virtual host has not been removed by the time that evhttp_free()
246    is called on the main http server, it will be automatically freed, too.
247 
248    It is possible to have hierarchical vhosts.  For example: A vhost
249    with the pattern *.example.com may have other vhosts with patterns
250    foo.example.com and bar.example.com associated with it.
251 
252    @param http the evhttp object to which to add a virtual host
253    @param pattern the glob pattern against which the hostname is matched.
254      The match is case insensitive and follows otherwise regular shell
255      matching.
256    @param vhost the virtual host to add the regular http server.
257    @return 0 on success, -1 on failure
258    @see evhttp_remove_virtual_host()
259 */
260 int evhttp_add_virtual_host(struct evhttp* http, const char *pattern,
261     struct evhttp* vhost);
262 
263 /**
264    Removes a virtual host from the http server.
265 
266    @param http the evhttp object from which to remove the virtual host
267    @param vhost the virtual host to remove from the regular http server.
268    @return 0 on success, -1 on failure
269    @see evhttp_add_virtual_host()
270 */
271 int evhttp_remove_virtual_host(struct evhttp* http, struct evhttp* vhost);
272 
273 /**
274    Add a server alias to an http object. The http object can be a virtual
275    host or the main server.
276 
277    @param http the evhttp object
278    @param alias the alias to add
279    @see evhttp_add_remove_alias()
280 */
281 int evhttp_add_server_alias(struct evhttp *http, const char *alias);
282 
283 /**
284    Remove a server alias from an http object.
285 
286    @param http the evhttp object
287    @param alias the alias to remove
288    @see evhttp_add_server_alias()
289 */
290 int evhttp_remove_server_alias(struct evhttp *http, const char *alias);
291 
292 /**
293  * Set the timeout for an HTTP request.
294  *
295  * @param http an evhttp object
296  * @param timeout_in_secs the timeout, in seconds
297  */
298 void evhttp_set_timeout(struct evhttp *http, int timeout_in_secs);
299 
300 /* Request/Response functionality */
301 
302 /**
303  * Send an HTML error message to the client.
304  *
305  * @param req a request object
306  * @param error the HTTP error code
307  * @param reason a brief explanation of the error.  If this is NULL, we'll
308  *    just use the standard meaning of the error code.
309  */
310 void evhttp_send_error(struct evhttp_request *req, int error,
311     const char *reason);
312 
313 /**
314  * Send an HTML reply to the client.
315  *
316  * The body of the reply consists of the data in databuf.  After calling
317  * evhttp_send_reply() databuf will be empty, but the buffer is still
318  * owned by the caller and needs to be deallocated by the caller if
319  * necessary.
320  *
321  * @param req a request object
322  * @param code the HTTP response code to send
323  * @param reason a brief message to send with the response code
324  * @param databuf the body of the response
325  */
326 void evhttp_send_reply(struct evhttp_request *req, int code,
327     const char *reason, struct evbuffer *databuf);
328 
329 /* Low-level response interface, for streaming/chunked replies */
330 
331 /**
332    Initiate a reply that uses Transfer-Encoding chunked.
333 
334    This allows the caller to stream the reply back to the client and is
335    useful when either not all of the reply data is immediately available
336    or when sending very large replies.
337 
338    The caller needs to supply data chunks with evhttp_send_reply_chunk()
339    and complete the reply by calling evhttp_send_reply_end().
340 
341    @param req a request object
342    @param code the HTTP response code to send
343    @param reason a brief message to send with the response code
344 */
345 void evhttp_send_reply_start(struct evhttp_request *req, int code,
346     const char *reason);
347 
348 /**
349    Send another data chunk as part of an ongoing chunked reply.
350 
351    The reply chunk consists of the data in databuf.  After calling
352    evhttp_send_reply_chunk() databuf will be empty, but the buffer is
353    still owned by the caller and needs to be deallocated by the caller
354    if necessary.
355 
356    @param req a request object
357    @param databuf the data chunk to send as part of the reply.
358 */
359 void evhttp_send_reply_chunk(struct evhttp_request *req,
360     struct evbuffer *databuf);
361 /**
362    Complete a chunked reply, freeing the request as appropriate.
363 
364    @param req a request object
365 */
366 void evhttp_send_reply_end(struct evhttp_request *req);
367 
368 /*
369  * Interfaces for making requests
370  */
371 
372 /** The different request types supported by evhttp.  These are as specified
373  * in RFC2616, except for PATCH which is specified by RFC5789.
374  *
375  * By default, only some of these methods are accepted and passed to user
376  * callbacks; use evhttp_set_allowed_methods() to change which methods
377  * are allowed.
378  */
379 enum evhttp_cmd_type {
380 	EVHTTP_REQ_GET     = 1 << 0,
381 	EVHTTP_REQ_POST    = 1 << 1,
382 	EVHTTP_REQ_HEAD    = 1 << 2,
383 	EVHTTP_REQ_PUT     = 1 << 3,
384 	EVHTTP_REQ_DELETE  = 1 << 4,
385 	EVHTTP_REQ_OPTIONS = 1 << 5,
386 	EVHTTP_REQ_TRACE   = 1 << 6,
387 	EVHTTP_REQ_CONNECT = 1 << 7,
388 	EVHTTP_REQ_PATCH   = 1 << 8
389 };
390 
391 /** a request object can represent either a request or a reply */
392 enum evhttp_request_kind { EVHTTP_REQUEST, EVHTTP_RESPONSE };
393 
394 /**
395  * Creates a new request object that needs to be filled in with the request
396  * parameters.  The callback is executed when the request completed or an
397  * error occurred.
398  */
399 struct evhttp_request *evhttp_request_new(
400 	void (*cb)(struct evhttp_request *, void *), void *arg);
401 
402 /**
403  * Enable delivery of chunks to requestor.
404  * @param cb will be called after every read of data with the same argument
405  *           as the completion callback. Will never be called on an empty
406  *           response. May drain the input buffer; it will be drained
407  *           automatically on return.
408  */
409 void evhttp_request_set_chunked_cb(struct evhttp_request *,
410     void (*cb)(struct evhttp_request *, void *));
411 
412 /** Frees the request object and removes associated events. */
413 void evhttp_request_free(struct evhttp_request *req);
414 
415 struct evdns_base;
416 
417 /**
418  * A connection object that can be used to for making HTTP requests.  The
419  * connection object tries to resolve address and establish the connection
420  * when it is given an http request object.
421  *
422  * @param base the event_base to use for handling the connection
423  * @param dnsbase the dns_base to use for resolving host names; if not
424  *     specified host name resolution will block.
425  * @param address the address to which to connect
426  * @param port the port to connect to
427  * @return an evhttp_connection object that can be used for making requests
428  */
429 struct evhttp_connection *evhttp_connection_base_new(
430 	struct event_base *base, struct evdns_base *dnsbase,
431 	const char *address, unsigned short port);
432 
433 /**
434  * Return the bufferevent that an evhttp_connection is using.
435  */
436 struct bufferevent *evhttp_connection_get_bufferevent(
437 	struct evhttp_connection *evcon);
438 
439 /** Takes ownership of the request object
440  *
441  * Can be used in a request callback to keep onto the request until
442  * evhttp_request_free() is explicitly called by the user.
443  */
444 void evhttp_request_own(struct evhttp_request *req);
445 
446 /** Returns 1 if the request is owned by the user */
447 int evhttp_request_is_owned(struct evhttp_request *req);
448 
449 /**
450  * Returns the connection object associated with the request or NULL
451  *
452  * The user needs to either free the request explicitly or call
453  * evhttp_send_reply_end().
454  */
455 struct evhttp_connection *evhttp_request_get_connection(struct evhttp_request *req);
456 
457 /**
458  * Returns the underlying event_base for this connection
459  */
460 struct event_base *evhttp_connection_get_base(struct evhttp_connection *req);
461 
462 void evhttp_connection_set_max_headers_size(struct evhttp_connection *evcon,
463     ev_ssize_t new_max_headers_size);
464 
465 void evhttp_connection_set_max_body_size(struct evhttp_connection* evcon,
466     ev_ssize_t new_max_body_size);
467 
468 /** Frees an http connection */
469 void evhttp_connection_free(struct evhttp_connection *evcon);
470 
471 /** sets the ip address from which http connections are made */
472 void evhttp_connection_set_local_address(struct evhttp_connection *evcon,
473     const char *address);
474 
475 /** sets the local port from which http connections are made */
476 void evhttp_connection_set_local_port(struct evhttp_connection *evcon,
477     ev_uint16_t port);
478 
479 /** Sets the timeout for events related to this connection */
480 void evhttp_connection_set_timeout(struct evhttp_connection *evcon,
481     int timeout_in_secs);
482 
483 /** Sets the retry limit for this connection - -1 repeats indefinitely */
484 void evhttp_connection_set_retries(struct evhttp_connection *evcon,
485     int retry_max);
486 
487 /** Set a callback for connection close. */
488 void evhttp_connection_set_closecb(struct evhttp_connection *evcon,
489     void (*)(struct evhttp_connection *, void *), void *);
490 
491 /** Get the remote address and port associated with this connection. */
492 void evhttp_connection_get_peer(struct evhttp_connection *evcon,
493     char **address, ev_uint16_t *port);
494 
495 /**
496     Make an HTTP request over the specified connection.
497 
498     The connection gets ownership of the request.  On failure, the
499     request object is no longer valid as it has been freed.
500 
501     @param evcon the evhttp_connection object over which to send the request
502     @param req the previously created and configured request object
503     @param type the request type EVHTTP_REQ_GET, EVHTTP_REQ_POST, etc.
504     @param uri the URI associated with the request
505     @return 0 on success, -1 on failure
506     @see evhttp_cancel_request()
507 */
508 int evhttp_make_request(struct evhttp_connection *evcon,
509     struct evhttp_request *req,
510     enum evhttp_cmd_type type, const char *uri);
511 
512 /**
513    Cancels a pending HTTP request.
514 
515    Cancels an ongoing HTTP request.  The callback associated with this request
516    is not executed and the request object is freed.  If the request is
517    currently being processed, e.g. it is ongoing, the corresponding
518    evhttp_connection object is going to get reset.
519 
520    A request cannot be canceled if its callback has executed already. A request
521    may be canceled reentrantly from its chunked callback.
522 
523    @param req the evhttp_request to cancel; req becomes invalid after this call.
524 */
525 void evhttp_cancel_request(struct evhttp_request *req);
526 
527 /**
528  * A structure to hold a parsed URI or Relative-Ref conforming to RFC3986.
529  */
530 struct evhttp_uri;
531 
532 /** Returns the request URI */
533 const char *evhttp_request_get_uri(const struct evhttp_request *req);
534 /** Returns the request URI (parsed) */
535 const struct evhttp_uri *evhttp_request_get_evhttp_uri(const struct evhttp_request *req);
536 /** Returns the request command */
537 enum evhttp_cmd_type evhttp_request_get_command(const struct evhttp_request *req);
538 
539 int evhttp_request_get_response_code(const struct evhttp_request *req);
540 
541 /** Returns the input headers */
542 struct evkeyvalq *evhttp_request_get_input_headers(struct evhttp_request *req);
543 /** Returns the output headers */
544 struct evkeyvalq *evhttp_request_get_output_headers(struct evhttp_request *req);
545 /** Returns the input buffer */
546 struct evbuffer *evhttp_request_get_input_buffer(struct evhttp_request *req);
547 /** Returns the output buffer */
548 struct evbuffer *evhttp_request_get_output_buffer(struct evhttp_request *req);
549 /** Returns the host associated with the request. If a client sends an absolute
550     URI, the host part of that is preferred. Otherwise, the input headers are
551     searched for a Host: header. NULL is returned if no absolute URI or Host:
552     header is provided. */
553 const char *evhttp_request_get_host(struct evhttp_request *req);
554 
555 /* Interfaces for dealing with HTTP headers */
556 
557 /**
558    Finds the value belonging to a header.
559 
560    @param headers the evkeyvalq object in which to find the header
561    @param key the name of the header to find
562    @returns a pointer to the value for the header or NULL if the header
563      count not be found.
564    @see evhttp_add_header(), evhttp_remove_header()
565 */
566 const char *evhttp_find_header(const struct evkeyvalq *headers,
567     const char *key);
568 
569 /**
570    Removes a header from a list of existing headers.
571 
572    @param headers the evkeyvalq object from which to remove a header
573    @param key the name of the header to remove
574    @returns 0 if the header was removed, -1  otherwise.
575    @see evhttp_find_header(), evhttp_add_header()
576 */
577 int evhttp_remove_header(struct evkeyvalq *headers, const char *key);
578 
579 /**
580    Adds a header to a list of existing headers.
581 
582    @param headers the evkeyvalq object to which to add a header
583    @param key the name of the header
584    @param value the value belonging to the header
585    @returns 0 on success, -1  otherwise.
586    @see evhttp_find_header(), evhttp_clear_headers()
587 */
588 int evhttp_add_header(struct evkeyvalq *headers, const char *key, const char *value);
589 
590 /**
591    Removes all headers from the header list.
592 
593    @param headers the evkeyvalq object from which to remove all headers
594 */
595 void evhttp_clear_headers(struct evkeyvalq *headers);
596 
597 /* Miscellaneous utility functions */
598 
599 
600 /**
601    Helper function to encode a string for inclusion in a URI.  All
602    characters are replaced by their hex-escaped (%22) equivalents,
603    except for characters explicitly unreserved by RFC3986 -- that is,
604    ASCII alphanumeric characters, hyphen, dot, underscore, and tilde.
605 
606    The returned string must be freed by the caller.
607 
608    @param str an unencoded string
609    @return a newly allocated URI-encoded string or NULL on failure
610  */
611 char *evhttp_encode_uri(const char *str);
612 
613 /**
614    As evhttp_encode_uri, but if 'size' is nonnegative, treat the string
615    as being 'size' bytes long.  This allows you to encode strings that
616    may contain 0-valued bytes.
617 
618    The returned string must be freed by the caller.
619 
620    @param str an unencoded string
621    @param size the length of the string to encode, or -1 if the string
622       is NUL-terminated
623    @param space_to_plus if true, space characters in 'str' are encoded
624       as +, not %20.
625    @return a newly allocate URI-encoded string, or NULL on failure.
626  */
627 char *evhttp_uriencode(const char *str, ev_ssize_t size, int space_to_plus);
628 
629 /**
630   Helper function to sort of decode a URI-encoded string.  Unlike
631   evhttp_get_decoded_uri, it decodes all plus characters that appear
632   _after_ the first question mark character, but no plusses that occur
633   before.  This is not a good way to decode URIs in whole or in part.
634 
635   The returned string must be freed by the caller
636 
637   @deprecated  This function is deprecated; you probably want to use
638      evhttp_get_decoded_uri instead.
639 
640   @param uri an encoded URI
641   @return a newly allocated unencoded URI or NULL on failure
642  */
643 char *evhttp_decode_uri(const char *uri);
644 
645 /**
646   Helper function to decode a URI-escaped string or HTTP parameter.
647 
648   If 'decode_plus' is 1, then we decode the string as an HTTP parameter
649   value, and convert all plus ('+') characters to spaces.  If
650   'decode_plus' is 0, we leave all plus characters unchanged.
651 
652   The returned string must be freed by the caller.
653 
654   @param uri a URI-encode encoded URI
655   @param decode_plus determines whether we convert '+' to sapce.
656   @param size_out if size_out is not NULL, *size_out is set to the size of the
657      returned string
658   @return a newly allocated unencoded URI or NULL on failure
659  */
660 char *evhttp_uridecode(const char *uri, int decode_plus,
661     size_t *size_out);
662 
663 /**
664    Helper function to parse out arguments in a query.
665 
666    Parsing a URI like
667 
668       http://foo.com/?q=test&s=some+thing
669 
670    will result in two entries in the key value queue.
671 
672    The first entry is: key="q", value="test"
673    The second entry is: key="s", value="some thing"
674 
675    @deprecated This function is deprecated as of Libevent 2.0.9.  Use
676      evhttp_uri_parse and evhttp_parse_query_str instead.
677 
678    @param uri the request URI
679    @param headers the head of the evkeyval queue
680    @return 0 on success, -1 on failure
681  */
682 int evhttp_parse_query(const char *uri, struct evkeyvalq *headers);
683 
684 /**
685    Helper function to parse out arguments from the query portion of an
686    HTTP URI.
687 
688    Parsing a query string like
689 
690      q=test&s=some+thing
691 
692    will result in two entries in the key value queue.
693 
694    The first entry is: key="q", value="test"
695    The second entry is: key="s", value="some thing"
696 
697    @param query_parse the query portion of the URI
698    @param headers the head of the evkeyval queue
699    @return 0 on success, -1 on failure
700  */
701 int evhttp_parse_query_str(const char *uri, struct evkeyvalq *headers);
702 
703 /**
704  * Escape HTML character entities in a string.
705  *
706  * Replaces <, >, ", ' and & with &lt;, &gt;, &quot;,
707  * &#039; and &amp; correspondingly.
708  *
709  * The returned string needs to be freed by the caller.
710  *
711  * @param html an unescaped HTML string
712  * @return an escaped HTML string or NULL on error
713  */
714 char *evhttp_htmlescape(const char *html);
715 
716 /**
717  * Return a new empty evhttp_uri with no fields set.
718  */
719 struct evhttp_uri *evhttp_uri_new(void);
720 
721 /**
722  * Changes the flags set on a given URI.  See EVHTTP_URI_* for
723  * a list of flags.
724  **/
725 void evhttp_uri_set_flags(struct evhttp_uri *uri, unsigned flags);
726 
727 /** Return the scheme of an evhttp_uri, or NULL if there is no scheme has
728  * been set and the evhttp_uri contains a Relative-Ref. */
729 const char *evhttp_uri_get_scheme(const struct evhttp_uri *uri);
730 /**
731  * Return the userinfo part of an evhttp_uri, or NULL if it has no userinfo
732  * set.
733  */
734 const char *evhttp_uri_get_userinfo(const struct evhttp_uri *uri);
735 /**
736  * Return the host part of an evhttp_uri, or NULL if it has no host set.
737  * The host may either be a regular hostname (conforming to the RFC 3986
738  * "regname" production), or an IPv4 address, or the empty string, or a
739  * bracketed IPv6 address, or a bracketed 'IP-Future' address.
740  *
741  * Note that having a NULL host means that the URI has no authority
742  * section, but having an empty-string host means that the URI has an
743  * authority section with no host part.  For example,
744  * "mailto:user@example.com" has a host of NULL, but "file:///etc/motd"
745  * has a host of "".
746  */
747 const char *evhttp_uri_get_host(const struct evhttp_uri *uri);
748 /** Return the port part of an evhttp_uri, or -1 if there is no port set. */
749 int evhttp_uri_get_port(const struct evhttp_uri *uri);
750 /** Return the path part of an evhttp_uri, or NULL if it has no path set */
751 const char *evhttp_uri_get_path(const struct evhttp_uri *uri);
752 /** Return the query part of an evhttp_uri (excluding the leading "?"), or
753  * NULL if it has no query set */
754 const char *evhttp_uri_get_query(const struct evhttp_uri *uri);
755 /** Return the fragment part of an evhttp_uri (excluding the leading "#"),
756  * or NULL if it has no fragment set */
757 const char *evhttp_uri_get_fragment(const struct evhttp_uri *uri);
758 
759 /** Set the scheme of an evhttp_uri, or clear the scheme if scheme==NULL.
760  * Returns 0 on success, -1 if scheme is not well-formed. */
761 int evhttp_uri_set_scheme(struct evhttp_uri *uri, const char *scheme);
762 /** Set the userinfo of an evhttp_uri, or clear the userinfo if userinfo==NULL.
763  * Returns 0 on success, -1 if userinfo is not well-formed. */
764 int evhttp_uri_set_userinfo(struct evhttp_uri *uri, const char *userinfo);
765 /** Set the host of an evhttp_uri, or clear the host if host==NULL.
766  * Returns 0 on success, -1 if host is not well-formed. */
767 int evhttp_uri_set_host(struct evhttp_uri *uri, const char *host);
768 /** Set the port of an evhttp_uri, or clear the port if port==-1.
769  * Returns 0 on success, -1 if port is not well-formed. */
770 int evhttp_uri_set_port(struct evhttp_uri *uri, int port);
771 /** Set the path of an evhttp_uri, or clear the path if path==NULL.
772  * Returns 0 on success, -1 if path is not well-formed. */
773 int evhttp_uri_set_path(struct evhttp_uri *uri, const char *path);
774 /** Set the query of an evhttp_uri, or clear the query if query==NULL.
775  * The query should not include a leading "?".
776  * Returns 0 on success, -1 if query is not well-formed. */
777 int evhttp_uri_set_query(struct evhttp_uri *uri, const char *query);
778 /** Set the fragment of an evhttp_uri, or clear the fragment if fragment==NULL.
779  * The fragment should not include a leading "#".
780  * Returns 0 on success, -1 if fragment is not well-formed. */
781 int evhttp_uri_set_fragment(struct evhttp_uri *uri, const char *fragment);
782 
783 /**
784  * Helper function to parse a URI-Reference as specified by RFC3986.
785  *
786  * This function matches the URI-Reference production from RFC3986,
787  * which includes both URIs like
788  *
789  *    scheme://[[userinfo]@]foo.com[:port]]/[path][?query][#fragment]
790  *
791  *  and relative-refs like
792  *
793  *    [path][?query][#fragment]
794  *
795  * Any optional elements portions not present in the original URI are
796  * left set to NULL in the resulting evhttp_uri.  If no port is
797  * specified, the port is set to -1.
798  *
799  * Note that no decoding is performed on percent-escaped characters in
800  * the string; if you want to parse them, use evhttp_uridecode or
801  * evhttp_parse_query_str as appropriate.
802  *
803  * Note also that most URI schemes will have additional constraints that
804  * this function does not know about, and cannot check.  For example,
805  * mailto://www.example.com/cgi-bin/fortune.pl is not a reasonable
806  * mailto url, http://www.example.com:99999/ is not a reasonable HTTP
807  * URL, and ftp:username@example.com is not a reasonable FTP URL.
808  * Nevertheless, all of these URLs conform to RFC3986, and this function
809  * accepts all of them as valid.
810  *
811  * @param source_uri the request URI
812  * @param flags Zero or more EVHTTP_URI_* flags to affect the behavior
813  *              of the parser.
814  * @return uri container to hold parsed data, or NULL if there is error
815  * @see evhttp_uri_free()
816  */
817 struct evhttp_uri *evhttp_uri_parse_with_flags(const char *source_uri,
818     unsigned flags);
819 
820 /** Tolerate URIs that do not conform to RFC3986.
821  *
822  * Unfortunately, some HTTP clients generate URIs that, according to RFC3986,
823  * are not conformant URIs.  If you need to support these URIs, you can
824  * do so by passing this flag to evhttp_uri_parse_with_flags.
825  *
826  * Currently, these changes are:
827  * <ul>
828  *   <li> Nonconformant URIs are allowed to contain otherwise unreasonable
829  *        characters in their path, query, and fragment components.
830  * </ul>
831  */
832 #define EVHTTP_URI_NONCONFORMANT 0x01
833 
834 /** Alias for evhttp_uri_parse_with_flags(source_uri, 0) */
835 struct evhttp_uri *evhttp_uri_parse(const char *source_uri);
836 
837 /**
838  * Free all memory allocated for a parsed uri.  Only use this for URIs
839  * generated by evhttp_uri_parse.
840  *
841  * @param uri container with parsed data
842  * @see evhttp_uri_parse()
843  */
844 void evhttp_uri_free(struct evhttp_uri *uri);
845 
846 /**
847  * Join together the uri parts from parsed data to form a URI-Reference.
848  *
849  * Note that no escaping of reserved characters is done on the members
850  * of the evhttp_uri, so the generated string might not be a valid URI
851  * unless the members of evhttp_uri are themselves valid.
852  *
853  * @param uri container with parsed data
854  * @param buf destination buffer
855  * @param limit destination buffer size
856  * @return an joined uri as string or NULL on error
857  * @see evhttp_uri_parse()
858  */
859 char *evhttp_uri_join(struct evhttp_uri *uri, char *buf, size_t limit);
860 
861 #ifdef __cplusplus
862 }
863 #endif
864 
865 #endif /* _EVENT2_HTTP_H_ */
866