linux系统编程-SOCKET通信基础编程(2)-TCP服务端创建

 

linux系统编程-SOCKET通信基础编程(0)-常用数据结构

linux系统编程-SOCKET通信基础编程(1)-TCP客户端创建

linux系统编程-SOCKET通信基础编程(2)-TCP服务端创建

 

 

 

1.服务端创建流程

1.1创建服务端scoket 

       socket 本身就时一个整型值，相当于一个文件描述符

int socket(int domain, int type, int protocol);
int server_sock = socket(AF_INET, SOCK_STREAM, 0);//注意这里使用的是 SOCK_STREAM 流套接口

1.2设置IP地址信息

struct sockaddr_in server_addr;
bzero(&server_addr, sizeof(struct sockaddr_in));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(SERVER_PORT);
server_addr.sin_addr.s_addr = INADDR_ANY;

1.3绑定IP地址信息

int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
ret = bind(server_sock, (struct sockaddr *)&server_addr, sizeof(server_addr));

1.4开始监听是否有链接和设置监听链接数量

int listen(int sockfd, int backlog);
ret = listen(server_sock, 5);

1.5开始等地啊接收客户端链接请求

int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);
int accept4(int sockfd, struct sockaddr *addr, socklen_t *addrlen, int flags);
client_sock = accept(server_sock, (struct sockaddr *)&client_addr, &addrlen);

1.6向客户端发送消息

send(sockfd, buf, len, flags);
ret = send(client_sock, buf, strlen(buf), 0);

1.7接收客户端消息

ssize_t  recv(int sockfd, void *buf, size_t len, int flags);
ret = recv(client_sock, buf, BUFLEN, 0);

1.8关闭socket

​​​​​​​close(socket);

1.9完整例程

#include <stdio.h>
#include <string.h>
#include <errno.h>

#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>

#define SERVER_PORT 6666
#define BUFLEN 256

int setup_socket()
{
	int ret = 0;
	
	//1,创建SOCKET, 服务器的服务套接字
	int server_sock = socket(AF_INET, SOCK_STREAM, 0);
	if(server_sock < 0)
	{
		perror("socket");
		goto SOCKET_ERR;
	}
	
	//2, 填充服务器的地址信息
	struct sockaddr_in server_addr;
	bzero(&server_addr, sizeof(struct sockaddr_in));
	server_addr.sin_family = AF_INET;
	server_addr.sin_port = htons(SERVER_PORT);
	server_addr.sin_addr.s_addr = INADDR_ANY; 
	
	//3,绑定
	ret = bind(server_sock, (struct sockaddr *)&server_addr, sizeof(server_addr));
	if(ret < 0)
	{
		perror("bind");
		goto SOCKET_ERR;
	}
	
	//设置可以复用地址
	int on = 1;
	if(setsockopt(server_sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1){
		perror("setsockopt");
		goto SOCKET_ERR;
	}
	
	//4, 监听
	ret = listen(server_sock, 5);
	if(ret < 0)
	{
		perror("listen");
		goto SOCKET_ERR;
	}
	
	return server_sock;

SOCKET_ERR:
	return -1;
}

int main()
{
	char buf[BUFLEN] = {0};
	int client_sock = 0, ret = 0;
	socklen_t addrlen=0;
	int server_sock = setup_socket();
	struct sockaddr_in client_addr;
	bzero(&client_addr, sizeof(client_addr));
    addrlen = sizeof(client_addr);
	if(server_sock < 0)
	{
		perror("setup_socket");
		goto SOCKET_ERR;
	}

	while(1)
	{
		//5, 接收连接
		client_sock = accept(server_sock, (struct sockaddr *)&client_addr, &addrlen);
		
		printf("accept connect form IP: %s, port:%d\n",(char *)inet_ntoa(client_addr.sin_addr.s_addr) , ntohl(client_addr.sin_port));
		
		//6, 读数据
		ret = recv(client_sock, buf, BUFLEN, 0);
		if(ret < 0)
		{
			perror("recv");
			goto SOCKET_ERR;
		}
		printf("recv cliet msg:%s\n", buf);
		
		//7, 发数据
		bzero(buf, BUFLEN);
		strcpy(buf, "Hello World!\n");
		ret = send(client_sock, buf, strlen(buf), 0);
		
		//8,关闭连接
		close(client_sock);	 
	}
	
SOCKET_ERR:	
	return 0;
}

附加 设置地址复用 

int on = 1;

if(setsockopt(server_sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
{
    perror("setsockopt");
    goto SOCKET_ERR;
}