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Diffstat (limited to 'libevent-2.0.20-stable/include/event2/rpc.h')
| -rw-r--r-- | libevent-2.0.20-stable/include/event2/rpc.h | 596 |
1 files changed, 596 insertions, 0 deletions
diff --git a/libevent-2.0.20-stable/include/event2/rpc.h b/libevent-2.0.20-stable/include/event2/rpc.h new file mode 100644 index 0000000..5272edc --- /dev/null +++ b/libevent-2.0.20-stable/include/event2/rpc.h @@ -0,0 +1,596 @@ +/* + * Copyright (c) 2006-2007 Niels Provos <provos@citi.umich.edu> + * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ +#ifndef _EVENT2_RPC_H_ +#define _EVENT2_RPC_H_ + +#ifdef __cplusplus +extern "C" { +#endif + +/** @file rpc.h + * + * This header files provides basic support for an RPC server and client. + * + * To support RPCs in a server, every supported RPC command needs to be + * defined and registered. + * + * EVRPC_HEADER(SendCommand, Request, Reply); + * + * SendCommand is the name of the RPC command. + * Request is the name of a structure generated by event_rpcgen.py. + * It contains all parameters relating to the SendCommand RPC. The + * server needs to fill in the Reply structure. + * Reply is the name of a structure generated by event_rpcgen.py. It + * contains the answer to the RPC. + * + * To register an RPC with an HTTP server, you need to first create an RPC + * base with: + * + * struct evrpc_base *base = evrpc_init(http); + * + * A specific RPC can then be registered with + * + * EVRPC_REGISTER(base, SendCommand, Request, Reply, FunctionCB, arg); + * + * when the server receives an appropriately formatted RPC, the user callback + * is invoked. The callback needs to fill in the reply structure. + * + * void FunctionCB(EVRPC_STRUCT(SendCommand)* rpc, void *arg); + * + * To send the reply, call EVRPC_REQUEST_DONE(rpc); + * + * See the regression test for an example. + */ + +/** + Determines if the member has been set in the message + + @param msg the message to inspect + @param member the member variable to test for presences + @return 1 if it's present or 0 otherwise. +*/ +#define EVTAG_HAS(msg, member) \ + ((msg)->member##_set == 1) + +#ifndef _EVENT2_RPC_COMPAT_H_ + +/** + Assigns a value to the member in the message. + + @param msg the message to which to assign a value + @param member the name of the member variable + @param value the value to assign +*/ +#define EVTAG_ASSIGN(msg, member, value) \ + (*(msg)->base->member##_assign)((msg), (value)) +/** + Assigns a value to the member in the message. + + @param msg the message to which to assign a value + @param member the name of the member variable + @param value the value to assign + @param len the length of the value +*/ +#define EVTAG_ASSIGN_WITH_LEN(msg, member, value, len) \ + (*(msg)->base->member##_assign)((msg), (value), (len)) +/** + Returns the value for a member. + + @param msg the message from which to get the value + @param member the name of the member variable + @param pvalue a pointer to the variable to hold the value + @return 0 on success, -1 otherwise. +*/ +#define EVTAG_GET(msg, member, pvalue) \ + (*(msg)->base->member##_get)((msg), (pvalue)) +/** + Returns the value for a member. + + @param msg the message from which to get the value + @param member the name of the member variable + @param pvalue a pointer to the variable to hold the value + @param plen a pointer to the length of the value + @return 0 on success, -1 otherwise. +*/ +#define EVTAG_GET_WITH_LEN(msg, member, pvalue, plen) \ + (*(msg)->base->member##_get)((msg), (pvalue), (plen)) + +#endif /* _EVENT2_RPC_COMPAT_H_ */ + +/** + Adds a value to an array. +*/ +#define EVTAG_ARRAY_ADD_VALUE(msg, member, value) \ + (*(msg)->base->member##_add)((msg), (value)) +/** + Allocates a new entry in the array and returns it. +*/ +#define EVTAG_ARRAY_ADD(msg, member) \ + (*(msg)->base->member##_add)(msg) +/** + Gets a variable at the specified offset from the array. +*/ +#define EVTAG_ARRAY_GET(msg, member, offset, pvalue) \ + (*(msg)->base->member##_get)((msg), (offset), (pvalue)) +/** + Returns the number of entries in the array. +*/ +#define EVTAG_ARRAY_LEN(msg, member) ((msg)->member##_length) + + +struct evbuffer; +struct event_base; +struct evrpc_req_generic; +struct evrpc_request_wrapper; +struct evrpc; + +/** The type of a specific RPC Message + * + * @param rpcname the name of the RPC message + */ +#define EVRPC_STRUCT(rpcname) struct evrpc_req__##rpcname + +struct evhttp_request; +struct evrpc_status; +struct evrpc_hook_meta; + +/** Creates the definitions and prototypes for an RPC + * + * You need to use EVRPC_HEADER to create structures and function prototypes + * needed by the server and client implementation. The structures have to be + * defined in an .rpc file and converted to source code via event_rpcgen.py + * + * @param rpcname the name of the RPC + * @param reqstruct the name of the RPC request structure + * @param replystruct the name of the RPC reply structure + * @see EVRPC_GENERATE() + */ +#define EVRPC_HEADER(rpcname, reqstruct, rplystruct) \ +EVRPC_STRUCT(rpcname) { \ + struct evrpc_hook_meta *hook_meta; \ + struct reqstruct* request; \ + struct rplystruct* reply; \ + struct evrpc* rpc; \ + struct evhttp_request* http_req; \ + struct evbuffer* rpc_data; \ +}; \ +int evrpc_send_request_##rpcname(struct evrpc_pool *, \ + struct reqstruct *, struct rplystruct *, \ + void (*)(struct evrpc_status *, \ + struct reqstruct *, struct rplystruct *, void *cbarg), \ + void *); + +struct evrpc_pool; + +/** use EVRPC_GENERATE instead */ +struct evrpc_request_wrapper *evrpc_make_request_ctx( + struct evrpc_pool *pool, void *request, void *reply, + const char *rpcname, + void (*req_marshal)(struct evbuffer*, void *), + void (*rpl_clear)(void *), + int (*rpl_unmarshal)(void *, struct evbuffer *), + void (*cb)(struct evrpc_status *, void *, void *, void *), + void *cbarg); + +/** Creates a context structure that contains rpc specific information. + * + * EVRPC_MAKE_CTX is used to populate a RPC specific context that + * contains information about marshaling the RPC data types. + * + * @param rpcname the name of the RPC + * @param reqstruct the name of the RPC request structure + * @param replystruct the name of the RPC reply structure + * @param pool the evrpc_pool over which to make the request + * @param request a pointer to the RPC request structure object + * @param reply a pointer to the RPC reply structure object + * @param cb the callback function to call when the RPC has completed + * @param cbarg the argument to supply to the callback + */ +#define EVRPC_MAKE_CTX(rpcname, reqstruct, rplystruct, \ + pool, request, reply, cb, cbarg) \ + evrpc_make_request_ctx(pool, request, reply, \ + #rpcname, \ + (void (*)(struct evbuffer *, void *))reqstruct##_marshal, \ + (void (*)(void *))rplystruct##_clear, \ + (int (*)(void *, struct evbuffer *))rplystruct##_unmarshal, \ + (void (*)(struct evrpc_status *, void *, void *, void *))cb, \ + cbarg) + +/** Generates the code for receiving and sending an RPC message + * + * EVRPC_GENERATE is used to create the code corresponding to sending + * and receiving a particular RPC message + * + * @param rpcname the name of the RPC + * @param reqstruct the name of the RPC request structure + * @param replystruct the name of the RPC reply structure + * @see EVRPC_HEADER() + */ +#define EVRPC_GENERATE(rpcname, reqstruct, rplystruct) \ + int evrpc_send_request_##rpcname(struct evrpc_pool *pool, \ + struct reqstruct *request, struct rplystruct *reply, \ + void (*cb)(struct evrpc_status *, \ + struct reqstruct *, struct rplystruct *, void *cbarg), \ + void *cbarg) { \ + return evrpc_send_request_generic(pool, request, reply, \ + (void (*)(struct evrpc_status *, void *, void *, void *))cb, \ + cbarg, \ + #rpcname, \ + (void (*)(struct evbuffer *, void *))reqstruct##_marshal, \ + (void (*)(void *))rplystruct##_clear, \ + (int (*)(void *, struct evbuffer *))rplystruct##_unmarshal); \ +} + +/** Provides access to the HTTP request object underlying an RPC + * + * Access to the underlying http object; can be used to look at headers or + * for getting the remote ip address + * + * @param rpc_req the rpc request structure provided to the server callback + * @return an struct evhttp_request object that can be inspected for + * HTTP headers or sender information. + */ +#define EVRPC_REQUEST_HTTP(rpc_req) (rpc_req)->http_req + +/** completes the server response to an rpc request */ +void evrpc_request_done(struct evrpc_req_generic *req); + +/** accessors for request and reply */ +void *evrpc_get_request(struct evrpc_req_generic *req); +void *evrpc_get_reply(struct evrpc_req_generic *req); + +/** Creates the reply to an RPC request + * + * EVRPC_REQUEST_DONE is used to answer a request; the reply is expected + * to have been filled in. The request and reply pointers become invalid + * after this call has finished. + * + * @param rpc_req the rpc request structure provided to the server callback + */ +#define EVRPC_REQUEST_DONE(rpc_req) do { \ + struct evrpc_req_generic *_req = (struct evrpc_req_generic *)(rpc_req); \ + evrpc_request_done(_req); \ +} while (0) + + +struct evrpc_base; +struct evhttp; + +/* functions to start up the rpc system */ + +/** Creates a new rpc base from which RPC requests can be received + * + * @param server a pointer to an existing HTTP server + * @return a newly allocated evrpc_base struct + * @see evrpc_free() + */ +struct evrpc_base *evrpc_init(struct evhttp *server); + +/** + * Frees the evrpc base + * + * For now, you are responsible for making sure that no rpcs are ongoing. + * + * @param base the evrpc_base object to be freed + * @see evrpc_init + */ +void evrpc_free(struct evrpc_base *base); + +/** register RPCs with the HTTP Server + * + * registers a new RPC with the HTTP server, each RPC needs to have + * a unique name under which it can be identified. + * + * @param base the evrpc_base structure in which the RPC should be + * registered. + * @param name the name of the RPC + * @param request the name of the RPC request structure + * @param reply the name of the RPC reply structure + * @param callback the callback that should be invoked when the RPC + * is received. The callback has the following prototype + * void (*callback)(EVRPC_STRUCT(Message)* rpc, void *arg) + * @param cbarg an additional parameter that can be passed to the callback. + * The parameter can be used to carry around state. + */ +#define EVRPC_REGISTER(base, name, request, reply, callback, cbarg) \ + evrpc_register_generic(base, #name, \ + (void (*)(struct evrpc_req_generic *, void *))callback, cbarg, \ + (void *(*)(void *))request##_new, NULL, \ + (void (*)(void *))request##_free, \ + (int (*)(void *, struct evbuffer *))request##_unmarshal, \ + (void *(*)(void *))reply##_new, NULL, \ + (void (*)(void *))reply##_free, \ + (int (*)(void *))reply##_complete, \ + (void (*)(struct evbuffer *, void *))reply##_marshal) + +/** + Low level function for registering an RPC with a server. + + Use EVRPC_REGISTER() instead. + + @see EVRPC_REGISTER() +*/ +int evrpc_register_rpc(struct evrpc_base *, struct evrpc *, + void (*)(struct evrpc_req_generic*, void *), void *); + +/** + * Unregisters an already registered RPC + * + * @param base the evrpc_base object from which to unregister an RPC + * @param name the name of the rpc to unregister + * @return -1 on error or 0 when successful. + * @see EVRPC_REGISTER() + */ +#define EVRPC_UNREGISTER(base, name) evrpc_unregister_rpc((base), #name) + +int evrpc_unregister_rpc(struct evrpc_base *base, const char *name); + +/* + * Client-side RPC support + */ + +struct evhttp_connection; +struct evrpc_status; + +/** launches an RPC and sends it to the server + * + * EVRPC_MAKE_REQUEST() is used by the client to send an RPC to the server. + * + * @param name the name of the RPC + * @param pool the evrpc_pool that contains the connection objects over which + * the request should be sent. + * @param request a pointer to the RPC request structure - it contains the + * data to be sent to the server. + * @param reply a pointer to the RPC reply structure. It is going to be filled + * if the request was answered successfully + * @param cb the callback to invoke when the RPC request has been answered + * @param cbarg an additional argument to be passed to the client + * @return 0 on success, -1 on failure + */ +#define EVRPC_MAKE_REQUEST(name, pool, request, reply, cb, cbarg) \ + evrpc_send_request_##name((pool), (request), (reply), (cb), (cbarg)) + +/** + Makes an RPC request based on the provided context. + + This is a low-level function and should not be used directly + unless a custom context object is provided. Use EVRPC_MAKE_REQUEST() + instead. + + @param ctx a context from EVRPC_MAKE_CTX() + @returns 0 on success, -1 otherwise. + @see EVRPC_MAKE_REQUEST(), EVRPC_MAKE_CTX() +*/ +int evrpc_make_request(struct evrpc_request_wrapper *ctx); + +/** creates an rpc connection pool + * + * a pool has a number of connections associated with it. + * rpc requests are always made via a pool. + * + * @param base a pointer to an struct event_based object; can be left NULL + * in singled-threaded applications + * @return a newly allocated struct evrpc_pool object + * @see evrpc_pool_free() + */ +struct evrpc_pool *evrpc_pool_new(struct event_base *base); +/** frees an rpc connection pool + * + * @param pool a pointer to an evrpc_pool allocated via evrpc_pool_new() + * @see evrpc_pool_new() + */ +void evrpc_pool_free(struct evrpc_pool *pool); + +/** + * Adds a connection over which rpc can be dispatched to the pool. + * + * The connection object must have been newly created. + * + * @param pool the pool to which to add the connection + * @param evcon the connection to add to the pool. + */ +void evrpc_pool_add_connection(struct evrpc_pool *pool, + struct evhttp_connection *evcon); + +/** + * Removes a connection from the pool. + * + * The connection object must have been newly created. + * + * @param pool the pool from which to remove the connection + * @param evcon the connection to remove from the pool. + */ +void evrpc_pool_remove_connection(struct evrpc_pool *pool, + struct evhttp_connection *evcon); + +/** + * Sets the timeout in secs after which a request has to complete. The + * RPC is completely aborted if it does not complete by then. Setting + * the timeout to 0 means that it never timeouts and can be used to + * implement callback type RPCs. + * + * Any connection already in the pool will be updated with the new + * timeout. Connections added to the pool after set_timeout has be + * called receive the pool timeout only if no timeout has been set + * for the connection itself. + * + * @param pool a pointer to a struct evrpc_pool object + * @param timeout_in_secs the number of seconds after which a request should + * timeout and a failure be returned to the callback. + */ +void evrpc_pool_set_timeout(struct evrpc_pool *pool, int timeout_in_secs); + +/** + * Hooks for changing the input and output of RPCs; this can be used to + * implement compression, authentication, encryption, ... + */ + +enum EVRPC_HOOK_TYPE { + EVRPC_INPUT, /**< apply the function to an input hook */ + EVRPC_OUTPUT /**< apply the function to an output hook */ +}; + +#ifndef WIN32 +/** Deprecated alias for EVRPC_INPUT. Not available on windows, where it + * conflicts with platform headers. */ +#define INPUT EVRPC_INPUT +/** Deprecated alias for EVRPC_OUTPUT. Not available on windows, where it + * conflicts with platform headers. */ +#define OUTPUT EVRPC_OUTPUT +#endif + +/** + * Return value from hook processing functions + */ + +enum EVRPC_HOOK_RESULT { + EVRPC_TERMINATE = -1, /**< indicates the rpc should be terminated */ + EVRPC_CONTINUE = 0, /**< continue processing the rpc */ + EVRPC_PAUSE = 1 /**< pause processing request until resumed */ +}; + +/** adds a processing hook to either an rpc base or rpc pool + * + * If a hook returns TERMINATE, the processing is aborted. On CONTINUE, + * the request is immediately processed after the hook returns. If the + * hook returns PAUSE, request processing stops until evrpc_resume_request() + * has been called. + * + * The add functions return handles that can be used for removing hooks. + * + * @param vbase a pointer to either struct evrpc_base or struct evrpc_pool + * @param hook_type either INPUT or OUTPUT + * @param cb the callback to call when the hook is activated + * @param cb_arg an additional argument for the callback + * @return a handle to the hook so it can be removed later + * @see evrpc_remove_hook() + */ +void *evrpc_add_hook(void *vbase, + enum EVRPC_HOOK_TYPE hook_type, + int (*cb)(void *, struct evhttp_request *, struct evbuffer *, void *), + void *cb_arg); + +/** removes a previously added hook + * + * @param vbase a pointer to either struct evrpc_base or struct evrpc_pool + * @param hook_type either INPUT or OUTPUT + * @param handle a handle returned by evrpc_add_hook() + * @return 1 on success or 0 on failure + * @see evrpc_add_hook() + */ +int evrpc_remove_hook(void *vbase, + enum EVRPC_HOOK_TYPE hook_type, + void *handle); + +/** resume a paused request + * + * @param vbase a pointer to either struct evrpc_base or struct evrpc_pool + * @param ctx the context pointer provided to the original hook call + */ +int +evrpc_resume_request(void *vbase, void *ctx, enum EVRPC_HOOK_RESULT res); + +/** adds meta data to request + * + * evrpc_hook_add_meta() allows hooks to add meta data to a request. for + * a client request, the meta data can be inserted by an outgoing request hook + * and retrieved by the incoming request hook. + * + * @param ctx the context provided to the hook call + * @param key a NUL-terminated c-string + * @param data the data to be associated with the key + * @param data_size the size of the data + */ +void evrpc_hook_add_meta(void *ctx, const char *key, + const void *data, size_t data_size); + +/** retrieves meta data previously associated + * + * evrpc_hook_find_meta() can be used to retrieve meta data associated to a + * request by a previous hook. + * @param ctx the context provided to the hook call + * @param key a NUL-terminated c-string + * @param data pointer to a data pointer that will contain the retrieved data + * @param data_size pointer to the size of the data + * @return 0 on success or -1 on failure + */ +int evrpc_hook_find_meta(void *ctx, const char *key, + void **data, size_t *data_size); + +/** + * returns the connection object associated with the request + * + * @param ctx the context provided to the hook call + * @return a pointer to the evhttp_connection object + */ +struct evhttp_connection *evrpc_hook_get_connection(void *ctx); + +/** + Function for sending a generic RPC request. + + Do not call this function directly, use EVRPC_MAKE_REQUEST() instead. + + @see EVRPC_MAKE_REQUEST() + */ +int evrpc_send_request_generic(struct evrpc_pool *pool, + void *request, void *reply, + void (*cb)(struct evrpc_status *, void *, void *, void *), + void *cb_arg, + const char *rpcname, + void (*req_marshal)(struct evbuffer *, void *), + void (*rpl_clear)(void *), + int (*rpl_unmarshal)(void *, struct evbuffer *)); + +/** + Function for registering a generic RPC with the RPC base. + + Do not call this function directly, use EVRPC_REGISTER() instead. + + @see EVRPC_REGISTER() + */ +int +evrpc_register_generic(struct evrpc_base *base, const char *name, + void (*callback)(struct evrpc_req_generic *, void *), void *cbarg, + void *(*req_new)(void *), void *req_new_arg, void (*req_free)(void *), + int (*req_unmarshal)(void *, struct evbuffer *), + void *(*rpl_new)(void *), void *rpl_new_arg, void (*rpl_free)(void *), + int (*rpl_complete)(void *), + void (*rpl_marshal)(struct evbuffer *, void *)); + +/** accessors for obscure and undocumented functionality */ +struct evrpc_pool* evrpc_request_get_pool(struct evrpc_request_wrapper *ctx); +void evrpc_request_set_pool(struct evrpc_request_wrapper *ctx, + struct evrpc_pool *pool); +void evrpc_request_set_cb(struct evrpc_request_wrapper *ctx, + void (*cb)(struct evrpc_status*, void *request, void *reply, void *arg), + void *cb_arg); + +#ifdef __cplusplus +} +#endif + +#endif /* _EVENT2_RPC_H_ */ |