基于UDP套接字编程实例

data.h

 1 #ifndef DATA_H
 2 #define DATA_H
 3 #include <stdio.h>
 4 #include <string.h>
 5 #include <sys/types.h>
 6 #include <sys/stat.h>
 7 #include <sys/socket.h>
 8 #include <stdlib.h>
 9 #include <unistd.h>
10 #include <netinet/in.h>
11 #include <arpa/inet.h>
12 #include <netdb.h>
13 #include <errno.h>
14 #define PORT 4578
15 #define maxn 100
16 
17 #endif

server.c

 1 #include "data.h"
 2 int main()
 3 {
 4     int sockfd;
 5     struct sockaddr_in server;
 6     struct sockaddr_in client;
 7     socklen_t len;
 8     int num;
 9     char buf[maxn];
10     if((sockfd = socket(AF_INET,SOCK_DGRAM,0)) == -1)
11     {
12         fprintf(stderr,"socket fail,error:%s
",strerror(errno));
13         return -1;
14     }
15     bzero(&server,sizeof(server));
16     server.sin_family = AF_INET;
17     server.sin_port = htons(PORT);
18     server.sin_addr.s_addr = htonl(INADDR_ANY);
19     if(bind(sockfd,(struct sockaddr*)&server,sizeof(server)) == -1)
20     {
21         fprintf(stderr,"bind fail,error:%s
",strerror(errno));
22         return -1;
23     }
24     len = sizeof(client);
25     bzero(&buf,sizeof(buf));
26     while(1)
27     {
28         num = recvfrom(sockfd,buf,maxn,0,(struct sockaddr*)&client,&len);
29         if(num < 0)
30         {
31             perror("recvfrom() error!
");
32             exit(1);
33         }
34         num--;
35         buf[num] = '';
36         printf("You got a message <%s> from client.
",buf);
37         printf("It is ip is %s,port is %d.
",
38             inet_ntoa(client.sin_addr), htons(client.sin_port));
39         sendto(sockfd,buf,strlen(buf),0,(struct sockaddr*)&client,len);
40         if(!strcmp(buf,"bye"))
41             break;
42     }
43     close(sockfd);
44 
45 }

client.c

#include "data.h"
int main()
{
    int sockfd,num;
    char sendbuf[maxn];
    char recvbuf[maxn];
    struct sockaddr_in server;
    struct sockaddr_in peer;
    if((sockfd = socket(AF_INET,SOCK_DGRAM,0)) == -1)
    {
        fprintf(stderr,"socket fail,error %s
",strerror(errno));
        exit(1);
    }
    bzero(&server,sizeof(server));
    server.sin_family = AF_INET;
    server.sin_port = htons(PORT);    
    server.sin_addr.s_addr = inet_addr("127.0.0.1");
    bzero(&sendbuf,sizeof(sendbuf));
    bzero(&recvbuf,sizeof(recvbuf));
    while(fgets(sendbuf,sizeof(sendbuf),stdin) != NULL)
    {
        int tt = strlen(sendbuf);
        sendto(sockfd,sendbuf,tt,0,(struct sockaddr*)&server,sizeof(server));
        socklen_t len;
        recvfrom(sockfd,recvbuf,maxn,0,NULL,NULL);
        printf("receive message is :");
        fputs(recvbuf,stdout);
        printf("
");
        bzero(&sendbuf,sizeof(sendbuf));
        bzero(&recvbuf,sizeof(recvbuf));
    }
    close(sockfd);
    return 0;
}

运行结果：