1 #include <arpa/inet.h>
2 #include <fcntl.h>
3 #include <signal.h>
4 #include <stdio.h>
5 #include <stdlib.h>
6 #include <string.h>
7 #include <unistd.h>
8 
9 #define CONN_QUEUE_SIZE 20
10 #define BUFFER_SIZE 1024
11 #define SERVER_PORT 12580
12 
13 int server_sockfd;
14 int conn;
15 
signal_handler(int signo)16 void signal_handler(int signo)
17 {
18 
19     printf("Server is exiting...\n");
20     close(conn);
21     close(server_sockfd);
22     exit(0);
23 }
24 
25 static char logo[] =
26     " ____                                      ___   ____ \n|  _ \\  _ __   __ _   __ _   ___   _ __   / _ \\ / ___| "
27     "\n| | | || '__| / _` | / _` | / _ \\ | '_ \\ | | | |\\___ \\  \n| |_| || |   | (_| || (_| || (_) || | | || |_| | "
28     "___) |\n|____/ |_|    \\__,_| \\__, | \\___/ |_| |_| \\___/ |____/ \n                     |___/     \n";
29 
tcp_server()30 void tcp_server()
31 {
32     printf("TCP Server is running...\n");
33     server_sockfd = socket(AF_INET, SOCK_STREAM, 0);
34     printf("socket() ok, server_sockfd=%d\n", server_sockfd);
35     struct sockaddr_in server_sockaddr;
36     server_sockaddr.sin_family = AF_INET;
37     server_sockaddr.sin_port = htons(SERVER_PORT);
38     server_sockaddr.sin_addr.s_addr = htonl(INADDR_ANY);
39 
40     if (bind(server_sockfd, (struct sockaddr *)&server_sockaddr, sizeof(server_sockaddr)))
41     {
42         perror("Server bind error.\n");
43         exit(1);
44     }
45 
46     printf("TCP Server is listening...\n");
47     if (listen(server_sockfd, CONN_QUEUE_SIZE) == -1)
48     {
49         perror("Server listen error.\n");
50         exit(1);
51     }
52 
53     printf("listen() ok\n");
54 
55     char buffer[BUFFER_SIZE];
56     struct sockaddr_in client_addr;
57     socklen_t client_length = sizeof(client_addr);
58     /*
59         Await a connection on socket FD.
60         When a connection arrives, open a new socket to communicate with it,
61         set *ADDR (which is *ADDR_LEN bytes long) to the address of the connecting
62         peer and *ADDR_LEN to the address's actual length, and return the
63         new socket's descriptor, or -1 for errors.
64      */
65     conn = accept(server_sockfd, (struct sockaddr *)&client_addr, &client_length);
66     printf("Connection established.\n");
67     if (conn < 0)
68     {
69         printf("Create connection failed, code=%d\n", conn);
70         exit(1);
71     }
72     send(conn, logo, sizeof(logo), 0);
73     while (1)
74     {
75         memset(buffer, 0, sizeof(buffer));
76         int len = recv(conn, buffer, sizeof(buffer), 0);
77         if (len <= 0)
78         {
79             printf("Receive data failed! len=%d\n", len);
80             break;
81         }
82         if (strcmp(buffer, "exit\n") == 0)
83         {
84             break;
85         }
86 
87         printf("Received: %s\n", buffer);
88         send(conn, buffer, len, 0);
89     }
90     close(conn);
91     close(server_sockfd);
92 }
93 
udp_server()94 void udp_server()
95 {
96     printf("UDP Server is running...\n");
97     server_sockfd = socket(AF_INET, SOCK_DGRAM, 0);
98     printf("socket() ok, server_sockfd=%d\n", server_sockfd);
99     struct sockaddr_in server_sockaddr;
100     server_sockaddr.sin_family = AF_INET;
101     server_sockaddr.sin_port = htons(SERVER_PORT);
102     server_sockaddr.sin_addr.s_addr = htonl(INADDR_ANY);
103 
104     if (bind(server_sockfd, (struct sockaddr *)&server_sockaddr, sizeof(server_sockaddr)))
105     {
106         perror("Server bind error.\n");
107         exit(1);
108     }
109 
110     printf("UDP Server is listening...\n");
111 
112     char buffer[BUFFER_SIZE];
113     struct sockaddr_in client_addr;
114     socklen_t client_length = sizeof(client_addr);
115 
116     while (1)
117     {
118         memset(buffer, 0, sizeof(buffer));
119         int len = recvfrom(server_sockfd, buffer, sizeof(buffer), 0, (struct sockaddr *)&client_addr, &client_length);
120         if (len <= 0)
121         {
122             printf("Receive data failed! len=%d", len);
123             break;
124         }
125         if (strcmp(buffer, "exit\n") == 0)
126         {
127             break;
128         }
129 
130         printf("Received: %s", buffer);
131         sendto(server_sockfd, buffer, len, 0, (struct sockaddr *)&client_addr, client_length);
132         printf("Send: %s", buffer);
133     }
134     close(conn);
135     close(server_sockfd);
136 }
137 
tcp_client()138 void tcp_client()
139 {
140     printf("Client is running...\n");
141     int client_sockfd = socket(AF_INET, SOCK_STREAM, 0);
142 
143     struct sockaddr_in server_addr = {0};
144     server_addr.sin_family = AF_INET;
145     server_addr.sin_port = htons(12581);
146     server_addr.sin_addr.s_addr = inet_addr("192.168.199.129");
147     printf("to connect\n");
148     if (connect(client_sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0)
149     {
150         perror("Failed to establish connection to server\n");
151         exit(1);
152     }
153     printf("connected to server\n");
154 
155     char sendbuf[BUFFER_SIZE] = {0};
156     char recvbuf[BUFFER_SIZE] = {0};
157 
158     int x = recv(client_sockfd, recvbuf, sizeof(recvbuf), 0);
159 
160     fputs(recvbuf, stdout);
161 
162     memset(recvbuf, 0, sizeof(recvbuf));
163 
164     while (1)
165     {
166         fgets(sendbuf, sizeof(sendbuf), stdin);
167         sendbuf[0] = 'a';
168 
169         // printf("to send\n");
170         send(client_sockfd, sendbuf, strlen(sendbuf), 0);
171         // printf("send ok\n");
172         if (strcmp(sendbuf, "exit\n") == 0)
173         {
174             break;
175         }
176 
177         int x = recv(client_sockfd, recvbuf, sizeof(recvbuf), 0);
178         if (x < 0)
179         {
180             printf("recv error, retval=%d\n", x);
181             break;
182         }
183 
184         fputs(recvbuf, stdout);
185 
186         memset(recvbuf, 0, sizeof(recvbuf));
187         memset(sendbuf, 0, sizeof(sendbuf));
188     }
189     close(client_sockfd);
190 }
191 
udp_client()192 void udp_client()
193 {
194     struct sockaddr_in addr;
195     int sockfd, len = 0;
196     int addr_len = sizeof(struct sockaddr_in);
197     char buffer[256];
198 
199     /* 建立socket，注意必须是SOCK_DGRAM */
200     if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
201     {
202         perror("socket");
203         exit(1);
204     }
205 
206     /* 填写sockaddr_in*/
207     bzero(&addr, sizeof(addr));
208     addr.sin_family = AF_INET;
209     addr.sin_port = htons(12581);
210     addr.sin_addr.s_addr = inet_addr("192.168.199.129");
211 
212     printf("to send logo\n");
213     sendto(sockfd, logo, sizeof(logo), 0, (struct sockaddr *)&addr, addr_len);
214     printf("send logo ok\n");
215     while (1)
216     {
217         bzero(buffer, sizeof(buffer));
218 
219         printf("Please enter a string to send to server: \n");
220 
221         /* 从标准输入设备取得字符串*/
222         len = read(STDIN_FILENO, buffer, sizeof(buffer));
223         printf("to send: %d\n", len);
224         /* 将字符串传送给server端*/
225         sendto(sockfd, buffer, len, 0, (struct sockaddr *)&addr, addr_len);
226 
227         /* 接收server端返回的字符串*/
228         len = recvfrom(sockfd, buffer, sizeof(buffer), 0, (struct sockaddr *)&addr, &addr_len);
229         printf("Receive from server: %s\n", buffer);
230     }
231 
232     return 0;
233 }
main()234 void main()
235 {
236     // signal(SIGKILL, signal_handler);
237     // signal(SIGINT, signal_handler);
238     tcp_server();
239     // udp_server();
240     // tcp_client();
241     // udp_client();
242 }