1 /*
2 * Copyright (c) 2006-2007 Niels Provos <provos@citi.umich.edu>
3 * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
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 _EVENT2_RPC_H_
28 #define _EVENT2_RPC_H_
29
30 #ifdef __cplusplus
31 extern "C" {
32 #endif
33
34 /** @file rpc.h
35 *
36 * This header files provides basic support for an RPC server and client.
37 *
38 * To support RPCs in a server, every supported RPC command needs to be
39 * defined and registered.
40 *
41 * EVRPC_HEADER(SendCommand, Request, Reply);
42 *
43 * SendCommand is the name of the RPC command.
44 * Request is the name of a structure generated by event_rpcgen.py.
45 * It contains all parameters relating to the SendCommand RPC. The
46 * server needs to fill in the Reply structure.
47 * Reply is the name of a structure generated by event_rpcgen.py. It
48 * contains the answer to the RPC.
49 *
50 * To register an RPC with an HTTP server, you need to first create an RPC
51 * base with:
52 *
53 * struct evrpc_base *base = evrpc_init(http);
54 *
55 * A specific RPC can then be registered with
56 *
57 * EVRPC_REGISTER(base, SendCommand, Request, Reply, FunctionCB, arg);
58 *
59 * when the server receives an appropriately formatted RPC, the user callback
60 * is invoked. The callback needs to fill in the reply structure.
61 *
62 * void FunctionCB(EVRPC_STRUCT(SendCommand)* rpc, void *arg);
63 *
64 * To send the reply, call EVRPC_REQUEST_DONE(rpc);
65 *
66 * See the regression test for an example.
67 */
68
69 /**
70 Determines if the member has been set in the message
71
72 @param msg the message to inspect
73 @param member the member variable to test for presences
74 @return 1 if it's present or 0 otherwise.
75 */
76 #define EVTAG_HAS(msg, member) \
77 ((msg)->member##_set == 1)
78
79 #ifndef _EVENT2_RPC_COMPAT_H_
80
81 /**
82 Assigns a value to the member in the message.
83
84 @param msg the message to which to assign a value
85 @param member the name of the member variable
86 @param value the value to assign
87 */
88 #define EVTAG_ASSIGN(msg, member, value) \
89 (*(msg)->base->member##_assign)((msg), (value))
90 /**
91 Assigns a value to the member in the message.
92
93 @param msg the message to which to assign a value
94 @param member the name of the member variable
95 @param value the value to assign
96 @param len the length of the value
97 */
98 #define EVTAG_ASSIGN_WITH_LEN(msg, member, value, len) \
99 (*(msg)->base->member##_assign)((msg), (value), (len))
100 /**
101 Returns the value for a member.
102
103 @param msg the message from which to get the value
104 @param member the name of the member variable
105 @param pvalue a pointer to the variable to hold the value
106 @return 0 on success, -1 otherwise.
107 */
108 #define EVTAG_GET(msg, member, pvalue) \
109 (*(msg)->base->member##_get)((msg), (pvalue))
110 /**
111 Returns the value for a member.
112
113 @param msg the message from which to get the value
114 @param member the name of the member variable
115 @param pvalue a pointer to the variable to hold the value
116 @param plen a pointer to the length of the value
117 @return 0 on success, -1 otherwise.
118 */
119 #define EVTAG_GET_WITH_LEN(msg, member, pvalue, plen) \
120 (*(msg)->base->member##_get)((msg), (pvalue), (plen))
121
122 #endif /* _EVENT2_RPC_COMPAT_H_ */
123
124 /**
125 Adds a value to an array.
126 */
127 #define EVTAG_ARRAY_ADD_VALUE(msg, member, value) \
128 (*(msg)->base->member##_add)((msg), (value))
129 /**
130 Allocates a new entry in the array and returns it.
131 */
132 #define EVTAG_ARRAY_ADD(msg, member) \
133 (*(msg)->base->member##_add)(msg)
134 /**
135 Gets a variable at the specified offset from the array.
136 */
137 #define EVTAG_ARRAY_GET(msg, member, offset, pvalue) \
138 (*(msg)->base->member##_get)((msg), (offset), (pvalue))
139 /**
140 Returns the number of entries in the array.
141 */
142 #define EVTAG_ARRAY_LEN(msg, member) ((msg)->member##_length)
143
144
145 struct evbuffer;
146 struct event_base;
147 struct evrpc_req_generic;
148 struct evrpc_request_wrapper;
149 struct evrpc;
150
151 /** The type of a specific RPC Message
152 *
153 * @param rpcname the name of the RPC message
154 */
155 #define EVRPC_STRUCT(rpcname) struct evrpc_req__##rpcname
156
157 struct evhttp_request;
158 struct evrpc_status;
159 struct evrpc_hook_meta;
160
161 /** Creates the definitions and prototypes for an RPC
162 *
163 * You need to use EVRPC_HEADER to create structures and function prototypes
164 * needed by the server and client implementation. The structures have to be
165 * defined in an .rpc file and converted to source code via event_rpcgen.py
166 *
167 * @param rpcname the name of the RPC
168 * @param reqstruct the name of the RPC request structure
169 * @param replystruct the name of the RPC reply structure
170 * @see EVRPC_GENERATE()
171 */
172 #define EVRPC_HEADER(rpcname, reqstruct, rplystruct) \
173 EVRPC_STRUCT(rpcname) { \
174 struct evrpc_hook_meta *hook_meta; \
175 struct reqstruct* request; \
176 struct rplystruct* reply; \
177 struct evrpc* rpc; \
178 struct evhttp_request* http_req; \
179 struct evbuffer* rpc_data; \
180 }; \
181 int evrpc_send_request_##rpcname(struct evrpc_pool *, \
182 struct reqstruct *, struct rplystruct *, \
183 void (*)(struct evrpc_status *, \
184 struct reqstruct *, struct rplystruct *, void *cbarg), \
185 void *);
186
187 struct evrpc_pool;
188
189 /** use EVRPC_GENERATE instead */
190 struct evrpc_request_wrapper *evrpc_make_request_ctx(
191 struct evrpc_pool *pool, void *request, void *reply,
192 const char *rpcname,
193 void (*req_marshal)(struct evbuffer*, void *),
194 void (*rpl_clear)(void *),
195 int (*rpl_unmarshal)(void *, struct evbuffer *),
196 void (*cb)(struct evrpc_status *, void *, void *, void *),
197 void *cbarg);
198
199 /** Creates a context structure that contains rpc specific information.
200 *
201 * EVRPC_MAKE_CTX is used to populate a RPC specific context that
202 * contains information about marshaling the RPC data types.
203 *
204 * @param rpcname the name of the RPC
205 * @param reqstruct the name of the RPC request structure
206 * @param replystruct the name of the RPC reply structure
207 * @param pool the evrpc_pool over which to make the request
208 * @param request a pointer to the RPC request structure object
209 * @param reply a pointer to the RPC reply structure object
210 * @param cb the callback function to call when the RPC has completed
211 * @param cbarg the argument to supply to the callback
212 */
213 #define EVRPC_MAKE_CTX(rpcname, reqstruct, rplystruct, \
214 pool, request, reply, cb, cbarg) \
215 evrpc_make_request_ctx(pool, request, reply, \
216 #rpcname, \
217 (void (*)(struct evbuffer *, void *))reqstruct##_marshal, \
218 (void (*)(void *))rplystruct##_clear, \
219 (int (*)(void *, struct evbuffer *))rplystruct##_unmarshal, \
220 (void (*)(struct evrpc_status *, void *, void *, void *))cb, \
221 cbarg)
222
223 /** Generates the code for receiving and sending an RPC message
224 *
225 * EVRPC_GENERATE is used to create the code corresponding to sending
226 * and receiving a particular RPC message
227 *
228 * @param rpcname the name of the RPC
229 * @param reqstruct the name of the RPC request structure
230 * @param replystruct the name of the RPC reply structure
231 * @see EVRPC_HEADER()
232 */
233 #define EVRPC_GENERATE(rpcname, reqstruct, rplystruct) \
234 int evrpc_send_request_##rpcname(struct evrpc_pool *pool, \
235 struct reqstruct *request, struct rplystruct *reply, \
236 void (*cb)(struct evrpc_status *, \
237 struct reqstruct *, struct rplystruct *, void *cbarg), \
238 void *cbarg) { \
239 return evrpc_send_request_generic(pool, request, reply, \
240 (void (*)(struct evrpc_status *, void *, void *, void *))cb, \
241 cbarg, \
242 #rpcname, \
243 (void (*)(struct evbuffer *, void *))reqstruct##_marshal, \
244 (void (*)(void *))rplystruct##_clear, \
245 (int (*)(void *, struct evbuffer *))rplystruct##_unmarshal); \
246 }
247
248 /** Provides access to the HTTP request object underlying an RPC
249 *
250 * Access to the underlying http object; can be used to look at headers or
251 * for getting the remote ip address
252 *
253 * @param rpc_req the rpc request structure provided to the server callback
254 * @return an struct evhttp_request object that can be inspected for
255 * HTTP headers or sender information.
256 */
257 #define EVRPC_REQUEST_HTTP(rpc_req) (rpc_req)->http_req
258
259 /** completes the server response to an rpc request */
260 void evrpc_request_done(struct evrpc_req_generic *req);
261
262 /** accessors for request and reply */
263 void *evrpc_get_request(struct evrpc_req_generic *req);
264 void *evrpc_get_reply(struct evrpc_req_generic *req);
265
266 /** Creates the reply to an RPC request
267 *
268 * EVRPC_REQUEST_DONE is used to answer a request; the reply is expected
269 * to have been filled in. The request and reply pointers become invalid
270 * after this call has finished.
271 *
272 * @param rpc_req the rpc request structure provided to the server callback
273 */
274 #define EVRPC_REQUEST_DONE(rpc_req) do { \
275 struct evrpc_req_generic *_req = (struct evrpc_req_generic *)(rpc_req); \
276 evrpc_request_done(_req); \
277 } while (0)
278
279
280 struct evrpc_base;
281 struct evhttp;
282
283 /* functions to start up the rpc system */
284
285 /** Creates a new rpc base from which RPC requests can be received
286 *
287 * @param server a pointer to an existing HTTP server
288 * @return a newly allocated evrpc_base struct
289 * @see evrpc_free()
290 */
291 struct evrpc_base *evrpc_init(struct evhttp *server);
292
293 /**
294 * Frees the evrpc base
295 *
296 * For now, you are responsible for making sure that no rpcs are ongoing.
297 *
298 * @param base the evrpc_base object to be freed
299 * @see evrpc_init
300 */
301 void evrpc_free(struct evrpc_base *base);
302
303 /** register RPCs with the HTTP Server
304 *
305 * registers a new RPC with the HTTP server, each RPC needs to have
306 * a unique name under which it can be identified.
307 *
308 * @param base the evrpc_base structure in which the RPC should be
309 * registered.
310 * @param name the name of the RPC
311 * @param request the name of the RPC request structure
312 * @param reply the name of the RPC reply structure
313 * @param callback the callback that should be invoked when the RPC
314 * is received. The callback has the following prototype
315 * void (*callback)(EVRPC_STRUCT(Message)* rpc, void *arg)
316 * @param cbarg an additional parameter that can be passed to the callback.
317 * The parameter can be used to carry around state.
318 */
319 #define EVRPC_REGISTER(base, name, request, reply, callback, cbarg) \
320 evrpc_register_generic(base, #name, \
321 (void (*)(struct evrpc_req_generic *, void *))callback, cbarg, \
322 (void *(*)(void *))request##_new, NULL, \
323 (void (*)(void *))request##_free, \
324 (int (*)(void *, struct evbuffer *))request##_unmarshal, \
325 (void *(*)(void *))reply##_new, NULL, \
326 (void (*)(void *))reply##_free, \
327 (int (*)(void *))reply##_complete, \
328 (void (*)(struct evbuffer *, void *))reply##_marshal)
329
330 /**
331 Low level function for registering an RPC with a server.
332
333 Use EVRPC_REGISTER() instead.
334
335 @see EVRPC_REGISTER()
336 */
337 int evrpc_register_rpc(struct evrpc_base *, struct evrpc *,
338 void (*)(struct evrpc_req_generic*, void *), void *);
339
340 /**
341 * Unregisters an already registered RPC
342 *
343 * @param base the evrpc_base object from which to unregister an RPC
344 * @param name the name of the rpc to unregister
345 * @return -1 on error or 0 when successful.
346 * @see EVRPC_REGISTER()
347 */
348 #define EVRPC_UNREGISTER(base, name) evrpc_unregister_rpc((base), #name)
349
350 int evrpc_unregister_rpc(struct evrpc_base *base, const char *name);
351
352 /*
353 * Client-side RPC support
354 */
355
356 struct evhttp_connection;
357 struct evrpc_status;
358
359 /** launches an RPC and sends it to the server
360 *
361 * EVRPC_MAKE_REQUEST() is used by the client to send an RPC to the server.
362 *
363 * @param name the name of the RPC
364 * @param pool the evrpc_pool that contains the connection objects over which
365 * the request should be sent.
366 * @param request a pointer to the RPC request structure - it contains the
367 * data to be sent to the server.
368 * @param reply a pointer to the RPC reply structure. It is going to be filled
369 * if the request was answered successfully
370 * @param cb the callback to invoke when the RPC request has been answered
371 * @param cbarg an additional argument to be passed to the client
372 * @return 0 on success, -1 on failure
373 */
374 #define EVRPC_MAKE_REQUEST(name, pool, request, reply, cb, cbarg) \
375 evrpc_send_request_##name((pool), (request), (reply), (cb), (cbarg))
376
377 /**
378 Makes an RPC request based on the provided context.
379
380 This is a low-level function and should not be used directly
381 unless a custom context object is provided. Use EVRPC_MAKE_REQUEST()
382 instead.
383
384 @param ctx a context from EVRPC_MAKE_CTX()
385 @returns 0 on success, -1 otherwise.
386 @see EVRPC_MAKE_REQUEST(), EVRPC_MAKE_CTX()
387 */
388 int evrpc_make_request(struct evrpc_request_wrapper *ctx);
389
390 /** creates an rpc connection pool
391 *
392 * a pool has a number of connections associated with it.
393 * rpc requests are always made via a pool.
394 *
395 * @param base a pointer to an struct event_based object; can be left NULL
396 * in singled-threaded applications
397 * @return a newly allocated struct evrpc_pool object
398 * @see evrpc_pool_free()
399 */
400 struct evrpc_pool *evrpc_pool_new(struct event_base *base);
401 /** frees an rpc connection pool
402 *
403 * @param pool a pointer to an evrpc_pool allocated via evrpc_pool_new()
404 * @see evrpc_pool_new()
405 */
406 void evrpc_pool_free(struct evrpc_pool *pool);
407
408 /**
409 * Adds a connection over which rpc can be dispatched to the pool.
410 *
411 * The connection object must have been newly created.
412 *
413 * @param pool the pool to which to add the connection
414 * @param evcon the connection to add to the pool.
415 */
416 void evrpc_pool_add_connection(struct evrpc_pool *pool,
417 struct evhttp_connection *evcon);
418
419 /**
420 * Removes a connection from the pool.
421 *
422 * The connection object must have been newly created.
423 *
424 * @param pool the pool from which to remove the connection
425 * @param evcon the connection to remove from the pool.
426 */
427 void evrpc_pool_remove_connection(struct evrpc_pool *pool,
428 struct evhttp_connection *evcon);
429
430 /**
431 * Sets the timeout in secs after which a request has to complete. The
432 * RPC is completely aborted if it does not complete by then. Setting
433 * the timeout to 0 means that it never timeouts and can be used to
434 * implement callback type RPCs.
435 *
436 * Any connection already in the pool will be updated with the new
437 * timeout. Connections added to the pool after set_timeout has be
438 * called receive the pool timeout only if no timeout has been set
439 * for the connection itself.
440 *
441 * @param pool a pointer to a struct evrpc_pool object
442 * @param timeout_in_secs the number of seconds after which a request should
443 * timeout and a failure be returned to the callback.
444 */
445 void evrpc_pool_set_timeout(struct evrpc_pool *pool, int timeout_in_secs);
446
447 /**
448 * Hooks for changing the input and output of RPCs; this can be used to
449 * implement compression, authentication, encryption, ...
450 */
451
452 enum EVRPC_HOOK_TYPE {
453 EVRPC_INPUT, /**< apply the function to an input hook */
454 EVRPC_OUTPUT /**< apply the function to an output hook */
455 };
456
457 #ifndef WIN32
458 /** Deprecated alias for EVRPC_INPUT. Not available on windows, where it
459 * conflicts with platform headers. */
460 #define INPUT EVRPC_INPUT
461 /** Deprecated alias for EVRPC_OUTPUT. Not available on windows, where it
462 * conflicts with platform headers. */
463 #define OUTPUT EVRPC_OUTPUT
464 #endif
465
466 /**
467 * Return value from hook processing functions
468 */
469
470 enum EVRPC_HOOK_RESULT {
471 EVRPC_TERMINATE = -1, /**< indicates the rpc should be terminated */
472 EVRPC_CONTINUE = 0, /**< continue processing the rpc */
473 EVRPC_PAUSE = 1 /**< pause processing request until resumed */
474 };
475
476 /** adds a processing hook to either an rpc base or rpc pool
477 *
478 * If a hook returns TERMINATE, the processing is aborted. On CONTINUE,
479 * the request is immediately processed after the hook returns. If the
480 * hook returns PAUSE, request processing stops until evrpc_resume_request()
481 * has been called.
482 *
483 * The add functions return handles that can be used for removing hooks.
484 *
485 * @param vbase a pointer to either struct evrpc_base or struct evrpc_pool
486 * @param hook_type either INPUT or OUTPUT
487 * @param cb the callback to call when the hook is activated
488 * @param cb_arg an additional argument for the callback
489 * @return a handle to the hook so it can be removed later
490 * @see evrpc_remove_hook()
491 */
492 void *evrpc_add_hook(void *vbase,
493 enum EVRPC_HOOK_TYPE hook_type,
494 int (*cb)(void *, struct evhttp_request *, struct evbuffer *, void *),
495 void *cb_arg);
496
497 /** removes a previously added hook
498 *
499 * @param vbase a pointer to either struct evrpc_base or struct evrpc_pool
500 * @param hook_type either INPUT or OUTPUT
501 * @param handle a handle returned by evrpc_add_hook()
502 * @return 1 on success or 0 on failure
503 * @see evrpc_add_hook()
504 */
505 int evrpc_remove_hook(void *vbase,
506 enum EVRPC_HOOK_TYPE hook_type,
507 void *handle);
508
509 /** resume a paused request
510 *
511 * @param vbase a pointer to either struct evrpc_base or struct evrpc_pool
512 * @param ctx the context pointer provided to the original hook call
513 */
514 int
515 evrpc_resume_request(void *vbase, void *ctx, enum EVRPC_HOOK_RESULT res);
516
517 /** adds meta data to request
518 *
519 * evrpc_hook_add_meta() allows hooks to add meta data to a request. for
520 * a client request, the meta data can be inserted by an outgoing request hook
521 * and retrieved by the incoming request hook.
522 *
523 * @param ctx the context provided to the hook call
524 * @param key a NUL-terminated c-string
525 * @param data the data to be associated with the key
526 * @param data_size the size of the data
527 */
528 void evrpc_hook_add_meta(void *ctx, const char *key,
529 const void *data, size_t data_size);
530
531 /** retrieves meta data previously associated
532 *
533 * evrpc_hook_find_meta() can be used to retrieve meta data associated to a
534 * request by a previous hook.
535 * @param ctx the context provided to the hook call
536 * @param key a NUL-terminated c-string
537 * @param data pointer to a data pointer that will contain the retrieved data
538 * @param data_size pointer to the size of the data
539 * @return 0 on success or -1 on failure
540 */
541 int evrpc_hook_find_meta(void *ctx, const char *key,
542 void **data, size_t *data_size);
543
544 /**
545 * returns the connection object associated with the request
546 *
547 * @param ctx the context provided to the hook call
548 * @return a pointer to the evhttp_connection object
549 */
550 struct evhttp_connection *evrpc_hook_get_connection(void *ctx);
551
552 /**
553 Function for sending a generic RPC request.
554
555 Do not call this function directly, use EVRPC_MAKE_REQUEST() instead.
556
557 @see EVRPC_MAKE_REQUEST()
558 */
559 int evrpc_send_request_generic(struct evrpc_pool *pool,
560 void *request, void *reply,
561 void (*cb)(struct evrpc_status *, void *, void *, void *),
562 void *cb_arg,
563 const char *rpcname,
564 void (*req_marshal)(struct evbuffer *, void *),
565 void (*rpl_clear)(void *),
566 int (*rpl_unmarshal)(void *, struct evbuffer *));
567
568 /**
569 Function for registering a generic RPC with the RPC base.
570
571 Do not call this function directly, use EVRPC_REGISTER() instead.
572
573 @see EVRPC_REGISTER()
574 */
575 int
576 evrpc_register_generic(struct evrpc_base *base, const char *name,
577 void (*callback)(struct evrpc_req_generic *, void *), void *cbarg,
578 void *(*req_new)(void *), void *req_new_arg, void (*req_free)(void *),
579 int (*req_unmarshal)(void *, struct evbuffer *),
580 void *(*rpl_new)(void *), void *rpl_new_arg, void (*rpl_free)(void *),
581 int (*rpl_complete)(void *),
582 void (*rpl_marshal)(struct evbuffer *, void *));
583
584 /** accessors for obscure and undocumented functionality */
585 struct evrpc_pool* evrpc_request_get_pool(struct evrpc_request_wrapper *ctx);
586 void evrpc_request_set_pool(struct evrpc_request_wrapper *ctx,
587 struct evrpc_pool *pool);
588 void evrpc_request_set_cb(struct evrpc_request_wrapper *ctx,
589 void (*cb)(struct evrpc_status*, void *request, void *reply, void *arg),
590 void *cb_arg);
591
592 #ifdef __cplusplus
593 }
594 #endif
595
596 #endif /* _EVENT2_RPC_H_ */