server.c

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<arpa/inet.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>


int main(int argc, char* argv[])
{

    if(argc!=3)
    {
        printf("Useage:[IP] [PORT]\n");
        return 1;
    }


    int sock=socket(AF_INET,SOCK_DGRAM,0);

    if(sock<0)
    {
        perror("socket");
        return 2;
    }

    struct sockaddr_in local;
    local.sin_family = AF_INET;
    local.sin_port = htons(atoi(argv[2]));
    local.sin_addr.s_addr = inet_addr(argv[1]);

    if(bind(sock,(struct sockaddr*)&local, sizeof(local))<0)
    {
        perror("bind");
        return 3;
    }

    char buf[8192];

    struct sockaddr_in client;
    while(1)
    {
        socklen_t len = sizeof(client);
        
        ssize_t s = recvfrom(sock ,buf,sizeof(buf)-1, 0, (struct sockaddr*)&client, &len);
       
        if(s>0)
        {
            buf[s]=0;
            printf("[%s:%d]: %s \n", inet_ntoa(client.sin_addr), ntohs(client.sin_port),buf); 

            sendto(sock,buf, strlen(buf), 0, (struct sockaddr*)&client, len);
        }
    }

    return 0;
}
 

client.c

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<arpa/inet.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>


int main(int argc, char* argv[])
{

    if(argc!=3)
    {
        printf("Useage:[IP] [PORT]\n");
        return 1;
    }


    int sock=socket(AF_INET,SOCK_DGRAM,0);

    if(sock<0)
    {
        perror("socket");
        return 2;
    }

    struct sockaddr_in server;
    server.sin_family = AF_INET;
    server.sin_port = htons(atoi(argv[2]));
    server.sin_addr.s_addr = inet_addr(argv[1]);

    char buf[8196];
    struct sockaddr_in peer;
    socklen_t len = sizeof(peer);
     
    while(1)
    {
         printf("Please Enter Your words:");
         fflush(stdout);

        ssize_t s = read(0, buf, sizeof(buf)-1);
       
        if(s>0)
        {
            buf[s-1]=0;
           
            sendto(sock, buf, strlen(buf), 0, (struct sockaddr*)&server, sizeof(server));
        
            ssize_t _s = recvfrom(sock, buf, sizeof(buf)-1, 0, (struct sockaddr*)&peer, &len);
            
            if(_s>0)
            {
                buf[s-1]=0;
                printf("server echo:%s\n", buf);
            }

        }
    }

    return 0;
}
 

Makefile

.PHONY:all
all:server client

server:server.c
	gcc -o [email protected] $^

client:client.c
	gcc -o [email protected] $^

.PHONY:clean
clean:
	rm server client