external/nameclient.c

How to get data from YARP's name server without using any YARP code in your own program.

How to get data from YARP's name server without using any YARP code in your own program.

/*
 * SPDX-FileCopyrightText: 2006-2021 Istituto Italiano di Tecnologia (IIT)
 * SPDX-FileCopyrightText: 2006-2010 RobotCub Consortium
 * SPDX-License-Identifier: BSD-3-Clause
 */
 
// If you are on Windows, make sure WIN32 is defined.
// otherwise, we assume UNIX.
 
// This simple demo program doesn't deal with fragmentation of tcp
// reads/writes.  If you're doing something serious, make sure you
// deal with cases where socket reads/writes are only partially completed.
// in one call.
 
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <string.h>
 
#ifdef WIN32
#include <winsock2.h>
#else
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#endif
 
// port number for yarp server
#define PORT        10000
 
// IP address or host name for yarp server
#define HOST        "127.0.0.1"
 
// buffer size for responses from name server
#define BUFSIZE     1000
 
#ifdef WIN32
void windowsNetStart(void) {
    int     wsaRc;
    WSADATA wsaData;
    if(wsaRc=WSAStartup(0x0101, &wsaData)) {
        perror("WinSock init");
    }
    if(wsaData.wVersion != 0x0101) {
        WSACleanup();
        perror("wsaData.wVersion");
    }
}
#endif
 
 
int main(int argc, char *argv[]) {
    char buf[BUFSIZE];
    int i;
#ifdef WIN32
    SOCKET sd;
#else
    int sd;
#endif
    //struct sockaddr_in sin;
    struct sockaddr_in pin;
    struct hostent *hp;
 
    if (argc<=1) {
        printf("Please supply a message to send to the nameserver. ");
        printf(" Examples:\n");
        printf("   help\n");
        printf("   list\n");
        printf("   query /portname\n");
        exit(1);
    }
 
#ifdef WIN32
    // start windows networking
    windowsNetStart();
#endif
 
    // get host information
    if ((hp = gethostbyname(HOST)) == 0) {
        perror("gethostbyname");
        exit(1);
    }
 
    // set up socket structure
    memset(&pin, 0, sizeof(pin));
    pin.sin_family = AF_INET;
    pin.sin_addr.s_addr = ((struct in_addr *)(hp->h_addr))->s_addr;
    pin.sin_port = htons(PORT);
 
    // get a socket
    if ((sd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        perror("socket");
        exit(1);
    }
 
    // connect to PORT on HOST
    if (connect(sd,(struct sockaddr *)  &pin, sizeof(pin)) == -1) {
        perror("connect");
        exit(1);
    }
 
    // Commands sent to the yarp server must begin with
    // "NAME_SERVER " and be terminated with "\n"
    buf[0] = '\0';
    strncat(buf,"NAME_SERVER",sizeof(buf));
    for (i=1; i<argc; i++) {
        strncat(buf," ",sizeof(buf));
        strncat(buf,argv[i],sizeof(buf));
    }
    strncat(buf,"\n",sizeof(buf));
    printf("Message to send to name server:\n");
    printf("%s", buf);
 
    // send a message to the server PORT on machine HOST
    if (send(sd, buf, strlen(buf), 0) == -1) {
        perror("send");
        exit(1);
    }
 
    // wait for a message to come back from the server
    for (i=0; i<BUFSIZE; i++) {
        buf[i] = '\0';
    }
    if (recv(sd, buf, BUFSIZE, 0) == -1) {
        perror("recv");
        exit(1);
    }
 
    // print out the results
    printf("Response from yarp server:\n");
    printf("%s", buf);
 
#ifdef WIN32
    closesocket(sd);
#else
    close(sd);
#endif
}