基于UDP协议的进程间通信

UDP协议的主要特点：
UDP是无连接的

UDP使用尽最大努力交付

UDP是面向报文的

没有拥塞控制

支持一对一、一对多、多对一、多对多的交互通信

UDP首部开销小

UDP协议是无连接的并且面向数据块的。所以client端不需要与server端进行连接，直接发送消息。

server：
1 #include<stdio.h>
2 #include<stdlib.h>
3 #include<sys/types.h>
4 #include<sys/socket.h>
5 #include<netinet/in.h>
6 #include<arpa/inet.h>
7 #include<string.h>
8 void usage(char *port)
9 {
10     printf("%s,[ip],[port]\n",port);
11 }
12 int main(int argc,char *argv[])
13 {
14     if(argc!=3)
15     {
16         usage(argv[0]);
17         exit(1);
18     }
19     int sock = socket(AF_INET,SOCK_DGRAM,0); //创建套接字
20     if(sock<0)
21     {
22         perror("socket");
23         return 1;
24     }
25     int port = atoi(argv[2]);
26     char *ip = argv[1];
27     struct sockaddr_in client;
28     client.sin_family = AF_INET;
29     client.sin_port = htons(port);
30     client.sin_addr.s_addr = inet_addr(ip);
31     if(bind(sock,(struct sockaddr*)&client,sizeof(client))<0)
32     {
33         perror("bind");
34         exit(1);
35     }
36     char buf[1024];
37     struct sockaddr_in remote;
38     socklen_t len = sizeof(remote);
39     while(1)
40     {
41         ssize_t size = recvfrom(sock,buf,sizeof(buf),0,(struct sockaddr*)&re    mote,&len);  //接收消息
42         if(size>0)
43         {
44             buf[size-1]='\0';
45             printf("%s,%d: %s\n",inet_ntoa(remote.sin_addr),ntohs(remote.sin    _port),buf);
46
47         }
48         else if(size==0)
49         {}
50         else
51         {
52             perror("recvfrom");
53             exit(2);
54         }
55         fflush(stdout);
56     }
57     return 0;
58 }

client：
1 #include<stdio.h>
2 #include<stdlib.h>
3 #include<sys/types.h>
4 #include<sys/socket.h>
5 #include<string.h>
6 #include<unistd.h>
7 #include<netinet/in.h>
8 #include<arpa/inet.h>
9 void usage(char *port)
10 {
11     printf("%s,[ip],[port]\n",port);
12 }
13 int main(int argc,char *argv[])
14 {
15     if(argc!=3)
16     {
17         usage(argv[0]);
18         exit(1);
19     }
20     int sock = socket(AF_INET,SOCK_DGRAM,0);
21     if(sock<0)
22     {
23         perror("socket");
24         return 1;
25     }
26     int port = atoi(argv[2]);
27     char *ip = argv[1];
28     struct sockaddr_in remote;
29     remote.sin_family = AF_INET;
30     remote.sin_port = htons(port);
31     remote.sin_addr.s_addr = inet_addr(ip);
32     char buf[1024];
33     while(1)
34     {
35         memset(buf,'\0',sizeof(buf));
36         ssize_t _s = read(0,buf,sizeof(buf)-1);
37         if(_s<0)
38         {
39             perror("read");
40             exit(1);
41         }
42         ssize_t size = sendto(sock,buf,strlen(buf),0,(struct sockaddr*)&remo    te,sizeof(remote)); //发送消息
43         if(size<0)
44         {
45             perror("sendto");
46             exit(1);
47         }
48
49     }
50     return 0;
51 }

[fbl@localhost udp]$ ./server 192.168.1.106 8080
192.168.1.106,33647: how are you
192.168.1.106,33647: hi
192.168.1.106,33647: hnxu
^C
[fbl@localhost udp]$
[fbl@localhost udp]$ ./client 192.168.1.106 8080
how are you
hi
hnxu
^C
[fbl@localhost udp]$