XML-RPC for C/C++ (Xmlrpc-c) Code

/* A simple standalone XML-RPC server program based on Abyss that contains a
   simple one-thread request processing loop.

   This uses the "provide your own Abyss server" mode of operation.

   xmlrpc_sample_add_server.c is a server that does the same thing, but
   does it by running a full Abyss daemon in the background, so it has
   less control over how the requests are served.
*/

#define _XOPEN_SOURCE 600
#define WIN32_LEAN_AND_MEAN  /* required by xmlrpc-c/server_abyss.h */

#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#ifndef _WIN32
#include <sys/socket.h>
#include <netinet/in.h>
#endif

#include <xmlrpc-c/base.h>
#include <xmlrpc-c/abyss.h>
#include <xmlrpc-c/server.h>
#include <xmlrpc-c/server_abyss.h>

#include "config.h"  /* information about this build environment */


static void
setupSignalHandlers(void) {

    /* In UNIX, when you try to write to a socket that has been closed
       from the other end, your write fails, but you also get a SIGPIPE
       signal.  That signal will kill you before you even have a chance
       to see the write fail unless you catch, block, or ignore it.
       If a client should connect to us and then disconnect before we've
       sent our response, we see this socket-closed behavior.  We
       obviously don't want to die just because a client didn't complete
       an RPC, so we ignore SIGPIPE.
    */
#ifndef _WIN32
    struct sigaction mysigaction;

    sigemptyset(&mysigaction.sa_mask);
    mysigaction.sa_flags = 0;
    mysigaction.sa_handler = SIG_IGN;
    sigaction(SIGPIPE, &mysigaction, NULL);
#endif
}



static void
printPeerIpAddr(TSession * const abyssSessionP) {

#ifdef _WIN32
    struct abyss_win_chaninfo * channelInfoP;
#else
    struct abyss_unix_chaninfo * channelInfoP;
#endif
    struct sockaddr_in * sockAddrInP;
    unsigned char * ipAddr;  /* 4 byte array */

    SessionGetChannelInfo(abyssSessionP, (void*)&channelInfoP);

    sockAddrInP = (struct sockaddr_in *) &channelInfoP->peerAddr;

    ipAddr = (unsigned char *)&sockAddrInP->sin_addr.s_addr;

    printf("RPC is from IP address %u.%u.%u.%u\n",
           ipAddr[0], ipAddr[1], ipAddr[2], ipAddr[3]);
}



static xmlrpc_value *
sample_add(xmlrpc_env *   const envP,
           xmlrpc_value * const paramArrayP,
           void *         const serverInfo,
           void *         const channelInfo) {

    xmlrpc_int x, y, z;

    printPeerIpAddr(channelInfo);

    /* Parse our argument array. */
    xmlrpc_decompose_value(envP, paramArrayP, "(ii)", &x, &y);
    if (envP->fault_occurred)
        return NULL;

    /* Add our two numbers. */
    z = x + y;

    /* Return our result. */
    return xmlrpc_build_value(envP, "i", z);
}



static xmlrpc_server_shutdown_fn requestShutdown;

static void
requestShutdown(xmlrpc_env * const faultP,
                void *       const context,
                const char * const comment,
                void *       const callInfo) {

    /* You make this run by executing the system method 'system.shutdown'.
       This function is registered in the method registry as the thing to call
       for that.
    */
    int * const terminationRequestedP = context;
    TSession * const abyssSessionP = callInfo;

    xmlrpc_env_init(faultP);

    fprintf(stderr, "Termination requested: %s\n", comment);

    printPeerIpAddr(abyssSessionP);

    *terminationRequestedP = 1;
}



int
main(int           const argc,
     const char ** const argv) {

    struct xmlrpc_method_info3 const methodInfo = {
        .methodName     = "sample.add",
        .methodFunction = &sample_add,
        .serverInfo = NULL
    };
    TServer abyssServer;
    xmlrpc_registry * registryP;
    xmlrpc_env env;
    int terminationRequested;  /* A boolean value */
    const char * error;

    if (argc-1 != 1) {
        fprintf(stderr, "You must specify 1 argument:  The TCP port number "
                "on which to listen for XML-RPC calls.  "
                "You specified %d.\n",  argc-1);
        exit(1);
    }

    AbyssInit(&error);

    xmlrpc_env_init(&env);

    registryP = xmlrpc_registry_new(&env);

    xmlrpc_registry_add_method3(&env, registryP, &methodInfo);

    xmlrpc_registry_set_shutdown(registryP,
                                 &requestShutdown, &terminationRequested);

    ServerCreate(&abyssServer, "XmlRpcServer", atoi(argv[1]), NULL, NULL);

    xmlrpc_server_abyss_set_handlers2(&abyssServer, "/RPC2", registryP);

    ServerInit(&abyssServer);

    setupSignalHandlers();

    terminationRequested = 0;

    while (!terminationRequested) {
        printf("Waiting for next RPC...\n");

        ServerRunOnce(&abyssServer);
            /* This waits for the next connection, accepts it, reads the
               HTTP POST request, executes the indicated RPC, and closes
               the connection.
            */
    }

    ServerFree(&abyssServer);

    AbyssTerm();

    return 0;
}