【Linux】TCP协议实现C/S模式

（一）简单C/S模型

（1）服务器端

• 代码：

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>
void Server()
{
    
    
	int sockfd = socket(AF_INET, SOCK_STREAM, 0);
	if(sockfd == -1)
	{
    
    
		perror("socket create err");
		return;
	}

	struct sockaddr_in saddr, caddr;
	int len_ser = sizeof(saddr);
	int len_cli = sizeof(caddr);

	memset(&saddr, 0, len_ser);
	memset(&caddr, 0, len_cli);

	saddr.sin_family = AF_INET;
	saddr.sin_port = htons(8000);
	saddr.sin_addr.s_addr = inet_addr("127.0.0.1");
	int ret = bind(sockfd, (struct sockaddr*)&saddr, len_ser);
	if(ret == -1)
	{
    
    
		perror("bind err");
		return;
	}

	ret = listen(sockfd, 5);
	if(ret == -1)
	{
    
    
		perror("listen err");
		return;
	}


	while(1)
	{
    
    
		printf("server have started, wait linking...\n");
		int cli_sockfd = accept(sockfd, (struct sockaddr*)&caddr, &len_cli);
		
		while(1)
		{
    
    
			char buff[128] = {
    
    0};
			ret = recv(cli_sockfd, buff, 127, 0);
			if(ret <= 0)
			{
    
    
				printf("one client close\n");
				close(cli_sockfd);
				break;
			}

			printf("cli : %s\n", buff);
			memset(buff, 0, 128);
			printf("input send to cli : ");
			fflush(stdout);
			fgets(buff, 127, stdin);
			int len = strlen(buff);
			buff[len - 1] = '\0';
			send(cli_sockfd, buff, len, 0);
		}
	}

	close(sockfd);
}

int main()
{
    
    
	Server();
	return 0;
}

（2）客户端

• 代码：

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>

void client()
{
    
    
	int sockfd = socket(AF_INET, SOCK_STREAM, 0);
	if(sockfd == -1)
	{
    
    
		perror("socket err");
		return;
	}

	struct sockaddr_in saddr;
	int len_ser = sizeof(saddr);
	memset(&saddr, 0, len_ser);

	saddr.sin_family = AF_INET;
	saddr.sin_port = htons(8000);
	saddr.sin_addr.s_addr = inet_addr("127.0.0.1");
	
	int ret = connect(sockfd, (struct sockaddr*)&saddr, len_ser);
	if(ret == -1)
	{
    
    
		perror("connect err");	
		return;
	}
	
	printf("connect sucessful...\n");
	while(1)
	{
    
    
		printf("input to server data:");
		fflush(stdout);

		char buff[128] = {
    
    0};
		fgets(buff, 127, stdin);
		int len = strlen(buff);
		buff[len - 1] = '\0';
		if(strcmp(buff, "end") == 0)
		{
    
    
			break;
		}
			
		send(sockfd, buff, len, 0);
		memset(buff, 0, 128);
		ret = recv(sockfd, buff, 127, 0);
		if(ret <= 0)
		{
    
    
			perror("server unnormal close");
			break;
		}
		printf("ser:%s\n", buff);
	}
	close(sockfd);
}

int main()
{
    
    
	client();
	return 0;
}

• 交互结果：
  
• 客户端连接服务器后使用netstat -natp查看下ip和端口的使用情况：