Linux环境下用C语言实现socket 通信---简单代码

Socket编程实例：

服务器端：一直监听本机的8000号端口，如果收到连接请求，将接收请求并接收客户端发来的消息，并向客户端返回消息。

客户端：client.c

 1 /* File Name: client.c */  
 2   
 3 #include<stdio.h>  
 4 #include<stdlib.h>  
 5 #include<string.h>  
 6 #include<errno.h>  
 7 #include<sys/types.h>  
 8 #include<sys/socket.h>  
 9 #include<netinet/in.h>  
10   
11 #define MAXLINE 4096  
12   
13   
14 int main(int argc, char** argv)  
15 {  
16     int    sockfd, n,rec_len;
17     int     i_port = 8000; //默认8000端口
18     
19     char    recvline[4096], sendline[4096];  
20     char    buf[MAXLINE];  
21     char   *c_ipAddr = "127.0.0.1";
22     
23     struct sockaddr_in    servaddr;      
24   
25     if( argc == 1)
26     {
27         printf("This client will connect server message: IP=127.0.0.1 , Port=8000 \n");        
28     }
29     else if( argc ==2 )
30     {
31         c_ipAddr = argv[1];
32         printf("This client will connect server message: IP=%s , Port=8000 \n",c_ipAddr);    
33     }
34     else if( argc == 3)
35     {
36         c_ipAddr = argv[1];    
37         i_port = atoi(argv[2]);
38         printf("This client will connect server message: IP=%s , Port=%d \n",c_ipAddr, i_port);    
39     }
40     else
41     {  
42         printf("usage: ./client <ipaddress> and port \n");  
43         exit(0);  
44     }  
45   
46       
47     if( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0){  
48     printf("create socket error: %s(errno: %d)\n", strerror(errno),errno);  
49     exit(0);  
50     }  
51   
52   
53     memset(&servaddr, 0, sizeof(servaddr));  
54     servaddr.sin_family = AF_INET;  
55     servaddr.sin_port = htons(i_port);  
56     
57     if( inet_pton(AF_INET, c_ipAddr, &servaddr.sin_addr) <= 0){  
58     printf("inet_pton error for %s\n",argv[1]);  
59     exit(0);  
60     }  
61   
62   
63     if( connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0){  
64     printf("connect error: %s(errno: %d)\n",strerror(errno),errno);  
65     exit(0);  
66     }  
67   
68   
69     printf("send msg to server: \n");  
70     fgets(sendline, 4096, stdin);  
71     if( send(sockfd, sendline, strlen(sendline), 0) < 0)  
72     {  
73     printf("send msg error: %s(errno: %d)\n", strerror(errno), errno);  
74     exit(0);  
75     }  
76     if((rec_len = recv(sockfd, buf, MAXLINE,0)) == -1) {  
77        perror("recv error");  
78        exit(1);  
79     }  
80     buf[rec_len]  = '\0';  
81     printf("Received : %s ",buf);  
82     close(sockfd);  
83     exit(0);  
84 }

服务端：server.c

 1 /* File Name: server.c */  
 2 #include<stdio.h>  
 3 #include<stdlib.h>  
 4 #include<string.h>  
 5 #include<errno.h>  
 6 #include<sys/types.h>  
 7 #include<sys/socket.h>  
 8 #include<netinet/in.h>  
 9 
10 
11 #define DEFAULT_PORT 8000  //监听端口号
12 #define MAXLINE 4096  
13 int main(int argc, char** argv)  
14 {  
15     int    socket_fd, connect_fd;  
16     struct sockaddr_in     servaddr;  
17     char    buff[4096];  
18     int     n;  
19     //初始化Socket  
20     if( (socket_fd = socket(AF_INET, SOCK_STREAM, 0)) == -1 ){  
21     printf("create socket error: %s(errno: %d)\n",strerror(errno),errno);  
22     exit(0);  
23     }  
24     //初始化  
25     memset(&servaddr, 0, sizeof(servaddr));  
26     servaddr.sin_family = AF_INET;  
27     servaddr.sin_addr.s_addr = htonl(INADDR_ANY);//IP地址设置成INADDR_ANY,让系统自动获取本机的IP地址。  
28     servaddr.sin_port = htons(DEFAULT_PORT);//设置的端口为DEFAULT_PORT  
29   
30     //将本地地址绑定到所创建的套接字上  
31     if( bind(socket_fd, (struct sockaddr*)&servaddr, sizeof(servaddr)) == -1){  
32     printf("bind socket error: %s(errno: %d)\n",strerror(errno),errno);  
33     exit(0);  
34     }  
35     //开始监听是否有客户端连接  
36     if( listen(socket_fd, 10) == -1){  
37     printf("listen socket error: %s(errno: %d)\n",strerror(errno),errno);  
38     exit(0);  
39     }  
40     printf("======waiting for client's request======\n");  
41     while(1){  
42 //阻塞直到有客户端连接，不然多浪费CPU资源。  
43         if( (connect_fd = accept(socket_fd, (struct sockaddr*)NULL, NULL)) == -1){  
44         printf("accept socket error: %s(errno: %d)",strerror(errno),errno);  
45         continue;  
46     }  
47 //接受客户端传过来的数据  
48     n = recv(connect_fd, buff, MAXLINE, 0);  
49 //向客户端发送回应数据  
50     if(!fork()){ /*子进程*/  
51         if(send(connect_fd, "Hello,you are connected!\n", 26,0) == -1)  
52         perror("send error");  
53         close(connect_fd);  
54         exit(0);  
55     }  
56     buff[n] = '\0';  
57     printf("recv msg from client: %s\n", buff);  
58     close(connect_fd);  
59     }  
60     close(socket_fd);  
61 }