一个基于UDP的广播小程序

   一个基于UDP的广播程序，包括服务器和客户端的代码，都很简单，就是在客户端广播一个消息，这样登录的服务器都能收到消息了。简单就不多说了，代码如下：

/*
 * filename: broadcast_client.c
 * DESC: the client endpoint of the UDP broadcast program
 * Author: linjian
 * Date: 2008/10/28
 */

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

#include "../my_error.h"

#define PORT 8003
#define BUF_SIZE 512

int main( int argc, char *argv[] )
{
    int sockfd;
    int optval;
    struct sockaddr_in serv_addr;
    char send_buf[ BUF_SIZE ];

    if ( argc != 2 ) {
        printf( "usage: ./broadcast_client [ip] \n" );
        exit ( EXIT_FAILURE );
    }

    /* we have to use the UDP for only the UDP support broadcast*/
    if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 )
        my_error( "socket failed" );

    /* set the broadcast option */
    optval = 1;
    if ( setsockopt(sockfd, SOL_SOCKET, SO_BROADCAST,
                 (void *)&optval, sizeof(int)) < 0 )
        my_error( "setsockopt" );

    memset( &serv_addr, 0, sizeof(struct sockaddr_in) );
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons( PORT );
    serv_addr.sin_addr.s_addr = inet_addr( argv[1] );

    printf( "input the string will be send:\n" );
    fgets( send_buf, BUF_SIZE, stdin );

    if ( sendto(sockfd, send_buf, strlen(send_buf), 0,
               (struct sockaddr *)&serv_addr,


                sizeof(struct sockaddr)) < 0 )
        my_error( "send failed" );

    close( sockfd );

    return 0;
}

/*  * filename: broadcast_serv.c  * DESC: the sever endpoint of the UDP broadcast program  * Author: linjian  * Date: 2008/10/28  */ #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <errno.h> #include <sys/types.h> #include <sys/socket.h> #include <arpa/inet.h> #include <netinet/in.h> #include "../my_error.h" #define PORT 8003 #define BUF_SIZE 512 int main( int argc, char *argv[] ) {     int sockfd, connfd;     int optval;     int client_len;     struct sockaddr_in serv_addr, client_addr;     char recv_buf[ BUF_SIZE ];     if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 )         my_error( "socket failed" );     memset( &serv_addr, 0, sizeof(struct sockaddr_in) );     serv_addr.sin_family = AF_INET;     serv_addr.sin_port = htons( PORT );     serv_addr.sin_addr.s_addr = htons( INADDR_ANY );     if ( bind(sockfd, (struct sockaddr *)&serv_addr,               sizeof(struct sockaddr)) < 0 )         my_error( "bind failed" );     client_len = sizeof( struct sockaddr_in );     if ( recvfrom(sockfd, recv_buf, BUF_SIZE, 0,                  (struct sockaddr *)&client_addr,                    &client_len) < 0 )         my_error( "recvfrom failed" );     printf( "recv from client: %s\n", recv_buf );     close( sockfd );     return 0; }

//客户端这边发送信息


ken@ken-laptop:~/linux_c/$./broadcase_client 192.168.18.255
input the string will be send:
This is ken

//服务器接受到了信息了


ken@kenlaptop:~/linux_c$ ./broadcase_serv
recv from client: This is ken