#include <sys/types.h>
#include <sys/socket.h>
int bind(int sockfd, const struct sockaddr* my_addr, socklen_t addrlen);

#include <unistd.h>
int close(int fd);

 1 #include <stdio.h>
 2 #include <sys/types.h>
 3 #include <sys/socket.h>
 4 #include <netinet/in.h>
 5 #include <string.h>
 6 
 7 #define SERVER_PORT 8888
 8 #define BUFF_LEN 1024
 9 
10 void handle_udp_msg(int fd)
11 {
12     char buf[BUFF_LEN];  //接收缓冲区，1024字节
13     socklen_t len;
14     int count;
15     struct sockaddr_in clent_addr;  //clent_addr用于记录发送方的地址信息
16     while(1)
17     {
18         memset(buf, 0, BUFF_LEN);
19         len = sizeof(clent_addr);
20         count = recvfrom(fd, buf, BUFF_LEN, 0, (struct sockaddr*)&clent_addr, &len);  //recvfrom是拥塞函数，没有数据就一直拥塞
21         if(count == -1)
22         {
23             printf("recieve data fail!\n");
24             return;
25         }
26         printf("client:%s\n",buf);  //打印client发过来的信息
27         memset(buf, 0, BUFF_LEN);
28         sprintf(buf, "I have recieved %d bytes data!\n", count);  //回复client
29         printf("server:%s\n",buf);  //打印自己发送的信息给
30         sendto(fd, buf, BUFF_LEN, 0, (struct sockaddr*)&clent_addr, len);  //发送信息给client，注意使用了clent_addr结构体指针
31 
32     }
33 }
34 
35 
36 /*
37     server:
38             socket-->bind-->recvfrom-->sendto-->close
39 */
40 
41 int main(int argc, char* argv[])
42 {
43     int server_fd, ret;
44     struct sockaddr_in ser_addr; 
45 
46     server_fd = socket(AF_INET, SOCK_DGRAM, 0); //AF_INET:IPV4;SOCK_DGRAM:UDP
47     if(server_fd < 0)
48     {
49         printf("create socket fail!\n");
50         return -1;
51     }
52 
53     memset(&ser_addr, 0, sizeof(ser_addr));
54     ser_addr.sin_family = AF_INET;
55     ser_addr.sin_addr.s_addr = htonl(INADDR_ANY); //IP地址，需要进行网络序转换，INADDR_ANY：本地地址
56     ser_addr.sin_port = htons(SERVER_PORT);  //端口号，需要网络序转换
57 
58     ret = bind(server_fd, (struct sockaddr*)&ser_addr, sizeof(ser_addr));
59     if(ret < 0)
60     {
61         printf("socket bind fail!\n");
62         return -1;
63     }
64 
65     handle_udp_msg(server_fd);   //处理接收到的数据
66 
67     close(server_fd);
68     return 0;
69 }

 1 #include <stdio.h>
 2 #include <sys/types.h>
 3 #include <sys/socket.h>
 4 #include <netinet/in.h>
 5 #include <string.h>
 6 
 7 #define SERVER_PORT 8888
 8 #define BUFF_LEN 512
 9 #define SERVER_IP "172.0.5.182"
10 
11 
12 void udp_msg_sender(int fd, struct sockaddr* dst)
13 {
14 
15     socklen_t len;
16     struct sockaddr_in src;
17     while(1)
18     {
19         char buf[BUFF_LEN] = "TEST UDP MSG!\n";
20         len = sizeof(*dst);
21         printf("client:%s\n",buf);  //打印自己发送的信息
22         sendto(fd, buf, BUFF_LEN, 0, dst, len);
23         memset(buf, 0, BUFF_LEN);
24         recvfrom(fd, buf, BUFF_LEN, 0, (struct sockaddr*)&src, &len);  //接收来自server的信息
25         printf("server:%s\n",buf);
26         sleep(1);  //一秒发送一次消息
27     }
28 }
29 
30 /*
31     client:
32             socket-->sendto-->revcfrom-->close
33 */
34 
35 int main(int argc, char* argv[])
36 {
37     int client_fd;
38     struct sockaddr_in ser_addr;
39 
40     client_fd = socket(AF_INET, SOCK_DGRAM, 0);
41     if(client_fd < 0)
42     {
43         printf("create socket fail!\n");
44         return -1;
45     }
46 
47     memset(&ser_addr, 0, sizeof(ser_addr));
48     ser_addr.sin_family = AF_INET;
49     //ser_addr.sin_addr.s_addr = inet_addr(SERVER_IP);
50     ser_addr.sin_addr.s_addr = htonl(INADDR_ANY);  //注意网络序转换
51     ser_addr.sin_port = htons(SERVER_PORT);  //注意网络序转换
52 
53     udp_msg_sender(client_fd, (struct sockaddr*)&ser_addr);
54 
55     close(client_fd);
56 
57     return 0;
58 }