2.2.server.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
  
#define PORT     8080
#define MAXLINE 1024

int main()
{
    int sockfd;
    char buffer[MAXLINE];
    char msgServer[MAXLINE];
    struct sockaddr_in servaddr, cliaddr;

    if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 )
    {
        perror("socket creation failed");
        exit(EXIT_FAILURE);
    }
      
    memset(&servaddr, 0, sizeof(servaddr));
    memset(&cliaddr, 0, sizeof(cliaddr));
      
    // Filling server information
    servaddr.sin_family    = AF_INET; // IPv4
    servaddr.sin_addr.s_addr = INADDR_ANY;
    servaddr.sin_port = htons(PORT);
      
    // Bind the socket with the server address
    if ( bind(sockfd, (const struct sockaddr *)&servaddr, sizeof(servaddr)) < 0 )
    {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }
      
    int len, n;
  
    len = sizeof(cliaddr);  //len is value/resuslt
    
    while(1)
    {
    	n = recvfrom(sockfd, (char *)buffer, MAXLINE, MSG_WAITALL, ( struct sockaddr *) &cliaddr, &len);
    	buffer[n] = '\0';
	    printf("%s\n", buffer);
	    if(strcmp(buffer, "exit") == 0)
	    {
	    	sendto(sockfd, "exit", strlen("exit"), MSG_CONFIRM, (const struct sockaddr *) &cliaddr, len);
    		return 0;
    	}
    	scanf("%s", &msgServer);
    	sendto(sockfd, msgServer, strlen(msgServer), MSG_CONFIRM, (const struct sockaddr *) &cliaddr, len);
	}
    
    return 0;
}