最简单的回声服务器源码

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#include <ctype.h>
#include <arpa/inet.h>

 

#define SERVER_PORT 666

int main(void){

int sock;//代表信箱
struct sockaddr_in server_addr;

//1.创建信箱
sock = socket(AF_INET, SOCK_STREAM, 0);

//2.清空标签，写上地址和端口号
bzero(&server_addr, sizeof(server_addr));

server_addr.sin_family = AF_INET;//选择协议族IPV4
server_addr.sin_addr.s_addr = htonl(INADDR_ANY);//监听本地所有IP地址
server_addr.sin_port = htons(SERVER_PORT);//绑定端口号

//实现标签贴到收信得信箱上
bind(sock, (struct sockaddr *)&server_addr, sizeof(server_addr));

//把信箱挂置到传达室，这样，就可以接收信件了
listen(sock, 128);

//万事俱备，只等来信
printf("等待客户端的连接\n");

int done =1;

while(done){
struct sockaddr_in client;
int client_sock, len;
char client_ip[64];
char buf[256];

socklen_t client_addr_len;
client_addr_len = sizeof(client);
client_sock = accept(sock, (struct sockaddr *)&client, &client_addr_len);

//打印客服端IP地址和端口号
printf("client ip: %s\t port : %d\n",
inet_ntop(AF_INET, &client.sin_addr.s_addr,client_ip,sizeof(client_ip)),
ntohs(client.sin_port));
/*读取客户端发送的数据*/
len = read(client_sock, buf, sizeof(buf)-1);
buf[len] = '\0';
printf("receive[%d]: %s\n", len, buf);

//转换成大写
for(i=0; i<len; i++){
/*if(buf[i]>='a' && buf[i]<='z'){
buf[i] = buf[i] - 32;
}*/
buf[i] = toupper(buf[i]);
}

len = write(client_sock, buf, len);

printf("finished. len: %d\n", len);
close(client_sock);

}
close(sock);
return 0;
}