Editing: rpc.h
/* * 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_INCLUDED_ #define EVENT2_RPC_H_INCLUDED_ #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_INCLUDED_ /** 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_INCLUDED_ */ /** 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_INCLUDED_ */
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