linux socket UDP编程发送广播

郁闷了几天，终于弄了出来，现在已经能发送广播了。
#include<stdio.h>
#include<stdlib.h>
#include<errno.h>
#include<string.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<sys/socket.h>
#include<sys/wait.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<unistd.h>
#include <arpa/inet.h>
#include<netdb.h>
#define PORT 7773
#define MAXDATASIZE 256
int main(int argc,char *argv[])
{
int socket_fd;
struct sockaddr_in my_addr,user_addr;
char buf[MAXDATASIZE];
int so_broadcast=1;
socklen_t size;
char my_ip[12];
my_addr.sin_family=AF_INET;
my_addr.sin_port=htons(PORT);
my_addr.sin_addr.s_addr=inet_addr("255.255.255.255");
bzero(&(my_addr.sin_zero),8);

user_addr.sin_family=AF_INET;
user_addr.sin_port=htons(PORT);
user_addr.sin_addr.s_addr=htonl(INADDR_ANY);
bzero(&(user_addr.sin_zero),8);
if((socket_fd=(socket(AF_INET,SOCK_DGRAM,0)))==-1) {
perror("socket");
exit(1);
}
setsockopt(socket_fd,SOL_SOCKET,SO_BROADCAST,&so_broadcast,sizeof(so_broadcast));
if((bind(socket_fd,(struct sockaddr *)&user_addr,
sizeof(struct sockaddr)))==-1) {
perror("bind");
exit(1);
}
strcpy(buf,"Hello,I'm on line!");
sendto(socket_fd,buf,strlen(buf),0,(struct sockaddr *)&my_addr,sizeof(my_addr));
size=sizeof(user_addr);
recvfrom(socket_fd,buf,MAXDATASIZE,0,(struct sockaddr *)&user_addr,&size);
strcpy(my_ip,inet_ntoa(user_addr.sin_addr));
printf("my_ip:%s\n",inet_ntoa(user_addr.sin_addr));
while(1) {
bzero(buf, sizeof(buf));
size=sizeof(user_addr);
recvfrom(socket_fd,buf,MAXDATASIZE,0,(struct sockaddr *)&user_addr,&size);
printf("%s:%s\n",inet_ntoa(user_addr.sin_addr),buf);
bzero(buf, sizeof(buf));
if(strcmp(buf,"I'm off line,bye!")==0)
strcpy(buf,"ok,I know,bye!");
else {
strcpy(buf,"send,Hello,I get you!");
sleep(1);
}
if((sendto(socket_fd,buf,strlen(buf),0,
(struct sockaddr *)&user_addr,sizeof(user_addr)))==-1)
perror("sendto");
}
return 0;
}
执行：
gcc -o udp udp.c
./udp

本文出自 “prothes blog” 博客，请务必保留此出处http://prothesman.blog.51cto.com/8610862/1411530