This code connects a client to the rpc-server. You need to specify the open interface of the server. It's IP in the IP_ADDR_SERVER macro. See rpc-server.c for furthur information.

rpc-client.c

#include <stdio.h> 
#include <sys/socket.h> 
#include <stdlib.h> 
#include <netinet/in.h> 
#include <string.h> 
#define PORT 12345 
#define IP_ADDR_SERVER "192.168.43.51" //YOU MAY NEED TO CHANGE THIS ADDRESS
   
int main(){ 
    struct sockaddr_in address; 
    int sock = 0, valread; 
    struct sockaddr_in serv_addr; 
    char buffer[1024] = {0}; 
    sock = socket(AF_INET, SOCK_STREAM, 0);
   
    memset(&serv_addr, '0', sizeof(serv_addr)); 
   
    serv_addr.sin_family = AF_INET; 
    serv_addr.sin_port = htons(PORT); 
       
    if(inet_pton(AF_INET, IP_ADDR_SERVER, &serv_addr.sin_addr)<=0)  
    { 
        printf("\nInvalid address/ Address not supported \n"); 
        return -1; 
    } 
   
    if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) 
    { 
        printf("\nConnection refused by server \n"); 
        return -1; 
    }
      
    valread = read(sock,buffer,1024); 
    printf("%s\n",buffer);
    printf("\nEnter the number : ");
    scanf("%s", buffer);
    send(sock, buffer, strlen(buffer), 0);
    char result[21];
    valread = read(sock, result, 21);
    printf("Factorial returned %s", result);
    return 0; 
}