listener.c

socket编程 客户端和服务器充分理解cs结构

/*
** listener.c -- a datagram sockets "server" demo
*/

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

#define MYPORT 4950    // the port users will be connecting to

#define MAXBUFLEN 100

int main(void)
{
    int sockfd;
    struct sockaddr_in my_addr;    // my address information
    struct sockaddr_in their_addr; // connector's address information
    int addr_len, numbytes;
    char buf[MAXBUFLEN];

    /* setup socket */
    if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
        perror("socket");
        exit(1);
    }

    my_addr.sin_family = AF_INET;         // host byte order
    my_addr.sin_port = htons(MYPORT);     // short, network byte order
    my_addr.sin_addr.s_addr = INADDR_ANY; // automatically fill with my IP
    memset(&(my_addr.sin_zero), '\0', 8); // zero the rest of the struct

    /* bind */
    if (bind(sockfd, (struct sockaddr *)&my_addr,
		sizeof(struct sockaddr)) == -1) {
        perror("bind");
        exit(1);
    }

    /* receive the string from the client and print it */
    while(1)
    {
        addr_len = sizeof(struct sockaddr);
        if ((numbytes=recvfrom(sockfd, buf, MAXBUFLEN-1 , 0,
		(struct sockaddr *)&their_addr, &addr_len)) == -1) {
            perror("recvfrom");
            exit(1);
        }

	buf[numbytes] = '\0';
        printf("%s says:%s",inet_ntoa(their_addr.sin_addr), buf);
    }

    close(sockfd);

	return 0;
}