简单的udp客户服务端程序

服务端程序：server.c

 1 #include <string.h>
 2 #include <unistd.h>
 3 #include <arpa/inet.h>
 4 #include <sys/types.h>
 5 #include <netinet/in.h>
 6 #include <stdio.h>
 7 
 8 
 9 
10 
11 #define PORT 12345
12 
13 int main()
14 {
15         struct sockaddr_in server_addr, client_addr;
16         char msg[1024];
17         int len;
18         static count = 1;
19         int fd = socket(AF_INET, SOCK_DGRAM, 0);
20         bzero(&server_addr, sizeof(struct sockaddr_in));
21 
22         server_addr.sin_family = AF_INET;
23         server_addr.sin_port = htons(PORT);
24         server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
25 
26         bind(fd, (struct sockaddr*)&server_addr, sizeof(struct sockaddr_in));
27 
28         socklen_t addr_len;
29         while(1)
30         {
31                 bzero(msg, sizeof(msg));
32                                 addr_len = sizeof(client_addr);
33                 len = recvfrom(fd, msg, sizeof(msg), 0, (struct sockaddr*)&client_addr, &addr_len);//百度百科直接搜
34                 printf("%d: ", len);
35                 printf("msg from: %s
", inet_ntoa(client_addr.sin_addr));
36                 printf("msg: %s
", msg);
37                 sendto(fd, msg, len, 0, (struct sockaddr*)&client_addr, addr_len);//百度百科直接搜
38 
39         }
40 
41         return 0;
42 
43 }

客户端程序：client.c

 1 #include <string.h>
 2 #include <unistd.h>
 3 #include <arpa/inet.h>
 4 #include <sys/types.h>
 5 #include <netinet/in.h>
 6 #include <stdio.h>
 7 
 8 
 9 
10 
11 #define PORT 12345 
12 #define IP "127.0.0.1"
13 int main()
14 {
15     struct sockaddr_in server_addr;
16     char msg[1024];
17     int len;
18     int fd = socket(AF_INET, SOCK_DGRAM, 0); //创建socket，注意udp创建的是数据包套接字，SOCK_DGRAM
19     if(fd < 0)
20     {
21         printf("socket error
");
22     }
23     bzero(&server_addr, sizeof(struct sockaddr_in)); //相当于memset(&server_addr, 0, sizeof(struct sockaddr_in));
24     
25     //指定服务端的端口和ip
26     server_addr.sin_family = AF_INET; 
27     server_addr.sin_port = htons(PORT);
28 
29     inet_pton(AF_INET, "127.0.0.1", &server_addr.sin_addr);
30     
31     
32     socklen_t addr_len;
33     int ret;
34     int n;
35     while(1)
36     {
37         //int n = read(STDIN_FILENO, msg, sizeof(msg));
38         fgets(msg, 1024, stdin); //用户输入字符串，fgets会读入字符'
'
39         printf(" msg: %s",  msg);
40         //发送到server端
41         ret = sendto(fd, msg, strlen(msg), 0, (struct sockaddr*)&server_addr, sizeof(server_addr));
42         printf("ret: %d
", ret);
43         //接收从服务端收到的字符串
44         n = recvfrom(fd, msg, sizeof(msg), 0, NULL, NULL);
45         printf("n=%d
", n);
46         msg[n]='';// 收到的字符串后面没有''，无法printf输出，所以在字符串后添加''
47         printf("%s", msg);
48         printf("__________________________________
");
49         
50     }
51     
52     return 0;
53     
54 }

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