UDP编程之二

广播模型

broadcast.c

#include <apue.h>

#define PORT 8088

int main(int argc,char **argv)
{
    if(argc!=2)
    {
        printf("%s <msg>
",argv[0]);
        exit(0);
    }

    int sockfd;
    if((sockfd = socket(AF_INET,SOCK_DGRAM,0))<0)
        ERR("socket failed");
    
    //设置允许广播
    int val = 1;
    if(setsockopt(sockfd,SOL_SOCKET,SO_BROADCAST,&val,sizeof(val))<0)
        ERR("setsockopt failed");

    struct sockaddr_in peer;
    CLEAR(peer);
    peer.sin_family = AF_INET;
    peer.sin_port = htons(PORT);
    inet_pton(AF_INET,"192.168.5.255",&peer.sin_addr);

    if(sendto(sockfd,argv[1],strlen(argv[1]),0,(struct sockaddr*)&peer,sizeof(peer))<0)
        ERR("send failed");
    
    close(sockfd);
    return 0;
}

recv.c

#include <apue.h>

#define PORT 8088

int main(int argc,char **argv)
{
    int sockfd;
    if((sockfd = socket(AF_INET,SOCK_DGRAM,0))<0)
        ERR("socket failed");
    
    struct sockaddr_in ipv4;
    CLEAR(ipv4);
    ipv4.sin_family = AF_INET;
    ipv4.sin_port = htons(PORT);
    ipv4.sin_addr.s_addr = htonl(INADDR_ANY);
    if(bind(sockfd,(struct sockaddr*)&ipv4,sizeof(ipv4))<0)
        ERR("bind failed");

    int n;
    char buf[255];
    while(1)
    {
        if((n = recvfrom(sockfd,buf,sizeof(buf),0,NULL,NULL))<0)
            ERR("recv failed");
        buf[n] = 0;
        printf("%s
",buf);
    }

    close(sockfd);
    return 0;
}