1 #include <stdio.h>
 2 #include <string.h>
 3 #include <stdlib.h>
 4 #include <errno.h>
 5 #include <sys/socket.h>
 6 #include <sys/types.h>
 7 #include <netinet/in.h>
 8 #include <unistd.h>
 9 #include <arpa/inet.h>
10 int main()
11 {
12     printf("
 
a server\n");
13     int listenfd = socket(AF_INET, SOCK_STREAM, 0);//建立一個socket描述符，唯一標識一個socket，socket()返回檔案描述符\
14         0,1,2分別表示標準輸入、標準輸出、標準錯誤，所以其他開啟的檔案描述符都會大於2, 錯誤時就返回 -1
15     if(listenfd == -1)
16     {
17         printf("error:socket\n");
18         return 0;
19     }
20 
21     struct sockaddr_in addr;
 
22     addr.sin_family = AF_INET;//IPV4
23     addr.sin_port = htons(8000);//host to net，主機位元組轉為網路位元組
24     addr.sin_addr.s_addr = INADDR_ANY;//指定ip地址：所有地址
25     if(bind(listenfd, (struct sockaddr*)&addr, sizeof(addr)) == -1)//bind()把地址和埠號組合賦給socket
26     {
27         printf("error:bind()\n");
28         return
 
 0;
29     }
30 
31     if(listen(listenfd, 5) == -1)//int listen( int sockfd/*用於標識一個已捆綁未連線套介面的描述字*/,\
32                                                              int backlog/*等待連線佇列最大長度*/);
33     {
34         printf("error:listen\n");
35         return 0;
36     }
37 
38     int conn;//客戶端套接字描述字
39     char clientIP[INET_ADDRSTRLEN];
40     struct sockaddr_in clientAddr;
41     socklen_t clientAddrLen = sizeof(clientAddr);
42     while(1)
43     {
44         printf("listening......\n");
45         conn = accept(listenfd, (struct sockaddr*)&clientAddr, &clientAddrLen);//監聽到之後，呼叫accept()
46         if(conn < 0)
47         {
48             printf("error:accept\n");
49             continue;
50         }
51         inet_ntop(AF_INET/*IPV4*/, &clientAddr.sin_addr/*source*/, clientIP/*destination*/, INET_ADDRSTRLEN/*IP長度*/);
52         /*在點分十進位制和二進位制整數轉換*/ 
53         printf("connect %s\n",clientIP);//IP:port
54 
55         char buff[255];
56         while(1)
57         {
58             for(int i=0; i<255; ++i)buff[i]=0;
59             int len = recv(conn, buff/*存放接收資料*/, sizeof(buff), 0/*一般置零*/);
60             buff[len] = '\0';
61             if(!strcmp(buff,"exit"))
62             {
63                 printf("disconnect\n");
64                 return 0;
65             }    
66             printf("%s\n",buff);
67             for(int i=0; i<len; ++i)
68             {
69                 buff[i] = toupper(buff[i]);
70             }
71             send(conn, buff, len, 0);
72         }
73         close(conn/*socket描述字*/);//關閉連線
74     }
75     close(listenfd);
76     return 0;
77 }

 1 #include <stdio.h>
 2 #include <string.h>
 3 #include <stdlib.h>
 4 #include <errno.h>
 5 #include <sys/socket.h>
 6 #include <sys/types.h>
 7 #include <netinet/in.h>
 8 #include <unistd.h>
 9 #include <arpa/inet.h>
10 int main() 
11 {
12     printf("a client\n");
13     // socket
14     int client = socket(AF_INET, SOCK_STREAM, 0);
15     if (client == -1) 
16     {
17         printf("error:socket\n");
18         return 0;
19     }
20     // connect
21     struct sockaddr_in serverAddr;
22     serverAddr.sin_family = AF_INET;
23     serverAddr.sin_port = htons(8000);
24     serverAddr.sin_addr.s_addr = inet_addr("192.168.246.140");//連線到master
25     if (connect(client, (struct sockaddr*)&serverAddr, sizeof(serverAddr)) < 0) 
26     {
27         printf("error:connect");
28         return 0;
29     }
30     printf("connect\n");
31     char data[255];
32     char result[255];
33     while (1) 
34     {
35         scanf("%s",data);
36         if(!strcmp(data,"exit"))
37         {
38             printf("disconnect");
39             break;
40         }
41         send(client, data, strlen(data), 0);
42         for(int i=0 ;i<sizeof(result);++i)result[i]=0;
43         int len = recv(client, result, sizeof(result), 0);
44         printf("result:%s\n",result);
45     }
46     close(client);
47     return 0;
48 }