487 lines
16 KiB
C
487 lines
16 KiB
C
/*
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* Copyright (c) 2006 Niels Provos <provos@citi.umich.edu>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _EVRPC_H_
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#define _EVRPC_H_
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#ifdef __cplusplus
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extern "C" {
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#endif
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/** @file evrpc.h
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*
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* This header files provides basic support for an RPC server and client.
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*
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* To support RPCs in a server, every supported RPC command needs to be
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* defined and registered.
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*
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* EVRPC_HEADER(SendCommand, Request, Reply);
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*
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* SendCommand is the name of the RPC command.
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* Request is the name of a structure generated by event_rpcgen.py.
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* It contains all parameters relating to the SendCommand RPC. The
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* server needs to fill in the Reply structure.
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* Reply is the name of a structure generated by event_rpcgen.py. It
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* contains the answer to the RPC.
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*
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* To register an RPC with an HTTP server, you need to first create an RPC
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* base with:
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*
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* struct evrpc_base *base = evrpc_init(http);
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*
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* A specific RPC can then be registered with
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*
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* EVRPC_REGISTER(base, SendCommand, Request, Reply, FunctionCB, arg);
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*
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* when the server receives an appropriately formatted RPC, the user callback
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* is invokved. The callback needs to fill in the reply structure.
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*
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* void FunctionCB(EVRPC_STRUCT(SendCommand)* rpc, void *arg);
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*
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* To send the reply, call EVRPC_REQUEST_DONE(rpc);
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*
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* See the regression test for an example.
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*/
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struct evbuffer;
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struct event_base;
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struct evrpc_req_generic;
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/* Encapsulates a request */
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struct evrpc {
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TAILQ_ENTRY(evrpc) next;
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/* the URI at which the request handler lives */
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const char* uri;
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/* creates a new request structure */
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void *(*request_new)(void);
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/* frees the request structure */
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void (*request_free)(void *);
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/* unmarshals the buffer into the proper request structure */
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int (*request_unmarshal)(void *, struct evbuffer *);
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/* creates a new reply structure */
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void *(*reply_new)(void);
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/* creates a new reply structure */
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void (*reply_free)(void *);
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/* verifies that the reply is valid */
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int (*reply_complete)(void *);
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/* marshals the reply into a buffer */
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void (*reply_marshal)(struct evbuffer*, void *);
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/* the callback invoked for each received rpc */
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void (*cb)(struct evrpc_req_generic *, void *);
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void *cb_arg;
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/* reference for further configuration */
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struct evrpc_base *base;
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};
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/** The type of a specific RPC Message
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*
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* @param rpcname the name of the RPC message
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*/
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#define EVRPC_STRUCT(rpcname) struct evrpc_req__##rpcname
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struct evhttp_request;
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struct evrpc_status;
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/* We alias the RPC specific structs to this voided one */
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struct evrpc_req_generic {
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/* the unmarshaled request object */
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void *request;
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/* the empty reply object that needs to be filled in */
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void *reply;
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/*
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* the static structure for this rpc; that can be used to
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* automatically unmarshal and marshal the http buffers.
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*/
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struct evrpc *rpc;
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/*
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* the http request structure on which we need to answer.
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*/
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struct evhttp_request* http_req;
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/*
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* callback to reply and finish answering this rpc
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*/
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void (*done)(struct evrpc_req_generic* rpc);
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};
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/** Creates the definitions and prototypes for an RPC
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*
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* You need to use EVRPC_HEADER to create structures and function prototypes
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* needed by the server and client implementation. The structures have to be
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* defined in an .rpc file and converted to source code via event_rpcgen.py
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*
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* @param rpcname the name of the RPC
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* @param reqstruct the name of the RPC request structure
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* @param replystruct the name of the RPC reply structure
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* @see EVRPC_GENERATE()
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*/
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#define EVRPC_HEADER(rpcname, reqstruct, rplystruct) \
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EVRPC_STRUCT(rpcname) { \
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struct reqstruct* request; \
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struct rplystruct* reply; \
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struct evrpc* rpc; \
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struct evhttp_request* http_req; \
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void (*done)(struct evrpc_status *, \
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struct evrpc* rpc, void *request, void *reply); \
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}; \
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int evrpc_send_request_##rpcname(struct evrpc_pool *, \
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struct reqstruct *, struct rplystruct *, \
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void (*)(struct evrpc_status *, \
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struct reqstruct *, struct rplystruct *, void *cbarg), \
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void *);
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/** Generates the code for receiving and sending an RPC message
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*
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* EVRPC_GENERATE is used to create the code corresponding to sending
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* and receiving a particular RPC message
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*
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* @param rpcname the name of the RPC
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* @param reqstruct the name of the RPC request structure
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* @param replystruct the name of the RPC reply structure
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* @see EVRPC_HEADER()
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*/
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#define EVRPC_GENERATE(rpcname, reqstruct, rplystruct) \
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int evrpc_send_request_##rpcname(struct evrpc_pool *pool, \
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struct reqstruct *request, struct rplystruct *reply, \
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void (*cb)(struct evrpc_status *, \
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struct reqstruct *, struct rplystruct *, void *cbarg), \
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void *cbarg) { \
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struct evrpc_status status; \
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struct evrpc_request_wrapper *ctx; \
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ctx = (struct evrpc_request_wrapper *) \
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malloc(sizeof(struct evrpc_request_wrapper)); \
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if (ctx == NULL) \
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goto error; \
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ctx->pool = pool; \
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ctx->evcon = NULL; \
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ctx->name = strdup(#rpcname); \
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if (ctx->name == NULL) { \
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free(ctx); \
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goto error; \
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} \
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ctx->cb = (void (*)(struct evrpc_status *, \
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void *, void *, void *))cb; \
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ctx->cb_arg = cbarg; \
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ctx->request = (void *)request; \
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ctx->reply = (void *)reply; \
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ctx->request_marshal = (void (*)(struct evbuffer *, void *))reqstruct##_marshal; \
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ctx->reply_clear = (void (*)(void *))rplystruct##_clear; \
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ctx->reply_unmarshal = (int (*)(void *, struct evbuffer *))rplystruct##_unmarshal; \
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return (evrpc_make_request(ctx)); \
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error: \
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memset(&status, 0, sizeof(status)); \
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status.error = EVRPC_STATUS_ERR_UNSTARTED; \
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(*(cb))(&status, request, reply, cbarg); \
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return (-1); \
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}
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/** Provides access to the HTTP request object underlying an RPC
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*
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* Access to the underlying http object; can be used to look at headers or
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* for getting the remote ip address
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*
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* @param rpc_req the rpc request structure provided to the server callback
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* @return an struct evhttp_request object that can be inspected for
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* HTTP headers or sender information.
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*/
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#define EVRPC_REQUEST_HTTP(rpc_req) (rpc_req)->http_req
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/** Creates the reply to an RPC request
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*
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* EVRPC_REQUEST_DONE is used to answer a request; the reply is expected
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* to have been filled in. The request and reply pointers become invalid
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* after this call has finished.
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*
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* @param rpc_req the rpc request structure provided to the server callback
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*/
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#define EVRPC_REQUEST_DONE(rpc_req) do { \
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struct evrpc_req_generic *_req = (struct evrpc_req_generic *)(rpc_req); \
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_req->done(_req); \
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} while (0)
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/* Takes a request object and fills it in with the right magic */
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#define EVRPC_REGISTER_OBJECT(rpc, name, request, reply) \
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do { \
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(rpc)->uri = strdup(#name); \
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if ((rpc)->uri == NULL) { \
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fprintf(stderr, "failed to register object\n"); \
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exit(1); \
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} \
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(rpc)->request_new = (void *(*)(void))request##_new; \
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(rpc)->request_free = (void (*)(void *))request##_free; \
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(rpc)->request_unmarshal = (int (*)(void *, struct evbuffer *))request##_unmarshal; \
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(rpc)->reply_new = (void *(*)(void))reply##_new; \
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(rpc)->reply_free = (void (*)(void *))reply##_free; \
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(rpc)->reply_complete = (int (*)(void *))reply##_complete; \
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(rpc)->reply_marshal = (void (*)(struct evbuffer*, void *))reply##_marshal; \
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} while (0)
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struct evrpc_base;
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struct evhttp;
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/* functions to start up the rpc system */
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/** Creates a new rpc base from which RPC requests can be received
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*
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* @param server a pointer to an existing HTTP server
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* @return a newly allocated evrpc_base struct
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* @see evrpc_free()
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*/
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struct evrpc_base *evrpc_init(struct evhttp *server);
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/**
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* Frees the evrpc base
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*
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* For now, you are responsible for making sure that no rpcs are ongoing.
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*
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* @param base the evrpc_base object to be freed
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* @see evrpc_init
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*/
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void evrpc_free(struct evrpc_base *base);
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/** register RPCs with the HTTP Server
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*
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* registers a new RPC with the HTTP server, each RPC needs to have
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* a unique name under which it can be identified.
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*
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* @param base the evrpc_base structure in which the RPC should be
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* registered.
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* @param name the name of the RPC
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* @param request the name of the RPC request structure
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* @param reply the name of the RPC reply structure
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* @param callback the callback that should be invoked when the RPC
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* is received. The callback has the following prototype
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* void (*callback)(EVRPC_STRUCT(Message)* rpc, void *arg)
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* @param cbarg an additional parameter that can be passed to the callback.
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* The parameter can be used to carry around state.
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*/
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#define EVRPC_REGISTER(base, name, request, reply, callback, cbarg) \
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do { \
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struct evrpc* rpc = (struct evrpc *)calloc(1, sizeof(struct evrpc)); \
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EVRPC_REGISTER_OBJECT(rpc, name, request, reply); \
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evrpc_register_rpc(base, rpc, \
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(void (*)(struct evrpc_req_generic*, void *))callback, cbarg); \
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} while (0)
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int evrpc_register_rpc(struct evrpc_base *, struct evrpc *,
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void (*)(struct evrpc_req_generic*, void *), void *);
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/**
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* Unregisters an already registered RPC
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*
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* @param base the evrpc_base object from which to unregister an RPC
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* @param name the name of the rpc to unregister
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* @return -1 on error or 0 when successful.
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* @see EVRPC_REGISTER()
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*/
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#define EVRPC_UNREGISTER(base, name) evrpc_unregister_rpc(base, #name)
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int evrpc_unregister_rpc(struct evrpc_base *base, const char *name);
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/*
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* Client-side RPC support
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*/
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struct evrpc_pool;
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struct evhttp_connection;
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/**
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* provides information about the completed RPC request.
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*/
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struct evrpc_status {
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#define EVRPC_STATUS_ERR_NONE 0
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#define EVRPC_STATUS_ERR_TIMEOUT 1
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#define EVRPC_STATUS_ERR_BADPAYLOAD 2
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#define EVRPC_STATUS_ERR_UNSTARTED 3
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#define EVRPC_STATUS_ERR_HOOKABORTED 4
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int error;
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/* for looking at headers or other information */
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struct evhttp_request *http_req;
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};
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struct evrpc_request_wrapper {
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TAILQ_ENTRY(evrpc_request_wrapper) next;
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/* pool on which this rpc request is being made */
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struct evrpc_pool *pool;
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/* connection on which the request is being sent */
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struct evhttp_connection *evcon;
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/* event for implementing request timeouts */
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struct event ev_timeout;
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/* the name of the rpc */
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char *name;
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/* callback */
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void (*cb)(struct evrpc_status*, void *request, void *reply, void *arg);
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void *cb_arg;
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void *request;
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void *reply;
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/* unmarshals the buffer into the proper request structure */
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void (*request_marshal)(struct evbuffer *, void *);
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/* removes all stored state in the reply */
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void (*reply_clear)(void *);
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/* marshals the reply into a buffer */
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int (*reply_unmarshal)(void *, struct evbuffer*);
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};
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/** launches an RPC and sends it to the server
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*
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* EVRPC_MAKE_REQUEST() is used by the client to send an RPC to the server.
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*
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* @param name the name of the RPC
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* @param pool the evrpc_pool that contains the connection objects over which
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* the request should be sent.
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* @param request a pointer to the RPC request structure - it contains the
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* data to be sent to the server.
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* @param reply a pointer to the RPC reply structure. It is going to be filled
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* if the request was answered successfully
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* @param cb the callback to invoke when the RPC request has been answered
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* @param cbarg an additional argument to be passed to the client
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* @return 0 on success, -1 on failure
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*/
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#define EVRPC_MAKE_REQUEST(name, pool, request, reply, cb, cbarg) \
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evrpc_send_request_##name(pool, request, reply, cb, cbarg)
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int evrpc_make_request(struct evrpc_request_wrapper *);
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/** creates an rpc connection pool
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*
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* a pool has a number of connections associated with it.
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* rpc requests are always made via a pool.
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*
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* @param base a pointer to an struct event_based object; can be left NULL
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* in singled-threaded applications
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* @return a newly allocated struct evrpc_pool object
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* @see evrpc_pool_free()
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*/
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struct evrpc_pool *evrpc_pool_new(struct event_base *base);
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/** frees an rpc connection pool
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*
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* @param pool a pointer to an evrpc_pool allocated via evrpc_pool_new()
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* @see evrpc_pool_new()
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*/
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void evrpc_pool_free(struct evrpc_pool *pool);
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/*
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* adds a connection over which rpc can be dispatched. the connection
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* object must have been newly created.
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*/
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void evrpc_pool_add_connection(struct evrpc_pool *,
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struct evhttp_connection *);
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/**
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* Sets the timeout in secs after which a request has to complete. The
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* RPC is completely aborted if it does not complete by then. Setting
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* the timeout to 0 means that it never timeouts and can be used to
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* implement callback type RPCs.
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*
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* Any connection already in the pool will be updated with the new
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* timeout. Connections added to the pool after set_timeout has be
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* called receive the pool timeout only if no timeout has been set
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* for the connection itself.
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*
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* @param pool a pointer to a struct evrpc_pool object
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* @param timeout_in_secs the number of seconds after which a request should
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* timeout and a failure be returned to the callback.
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*/
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void evrpc_pool_set_timeout(struct evrpc_pool *pool, int timeout_in_secs);
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/**
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* Hooks for changing the input and output of RPCs; this can be used to
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* implement compression, authentication, encryption, ...
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*/
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enum EVRPC_HOOK_TYPE {
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EVRPC_INPUT, /**< apply the function to an input hook */
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EVRPC_OUTPUT /**< apply the function to an output hook */
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};
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#ifndef WIN32
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/** Deprecated alias for EVRPC_INPUT. Not available on windows, where it
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* conflicts with platform headers. */
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#define INPUT EVRPC_INPUT
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/** Deprecated alias for EVRPC_OUTPUT. Not available on windows, where it
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* conflicts with platform headers. */
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#define OUTPUT EVRPC_OUTPUT
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#endif
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/** adds a processing hook to either an rpc base or rpc pool
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*
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* If a hook returns -1, the processing is aborted.
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*
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* The add functions return handles that can be used for removing hooks.
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*
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* @param vbase a pointer to either struct evrpc_base or struct evrpc_pool
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* @param hook_type either INPUT or OUTPUT
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* @param cb the callback to call when the hook is activated
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* @param cb_arg an additional argument for the callback
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* @return a handle to the hook so it can be removed later
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* @see evrpc_remove_hook()
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*/
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void *evrpc_add_hook(void *vbase,
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enum EVRPC_HOOK_TYPE hook_type,
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int (*cb)(struct evhttp_request *, struct evbuffer *, void *),
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void *cb_arg);
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/** removes a previously added hook
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*
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* @param vbase a pointer to either struct evrpc_base or struct evrpc_pool
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* @param hook_type either INPUT or OUTPUT
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* @param handle a handle returned by evrpc_add_hook()
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* @return 1 on success or 0 on failure
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* @see evrpc_add_hook()
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*/
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int evrpc_remove_hook(void *vbase,
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enum EVRPC_HOOK_TYPE hook_type,
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void *handle);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _EVRPC_H_ */
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