linux下TCP编程示例（服务端/客户端）

1. 前言

1.1 TCP编程模型(服务端/客户端)

1.2 编程步骤

(1)服务端:

    ①创建套接字

    ②绑定本地地址和端口号

    ③侦听客户端的连接请求

    ④接受客户端的连接请求

    ⑤接收客户端发来的消息

    ⑥发送消息给客户端

    ⑦关闭套接字

(2)客户端

    ①创建套接字

    ②连接服务器

    ③发送消息给服务器

    ④接收服务器的回应

    ⑤关闭套接字

2. 服务端示例程序

2.1 单服务器

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

#define PORT 10000

int main(){
	//1.创建套接字
	int sid = socket(AF_INET,SOCK_STREAM,0);
	if(sid < 0 ){
		perror("socket");
		exit(-1);
	}

	struct sockaddr_in saddr,caddr;
	saddr.sin_family = AF_INET;
	saddr.sin_port = htons(PORT);
	saddr.sin_addr.s_addr = INADDR_ANY;
	
	//2.绑定本地地址和端口号
	int iRet = bind(sid,(struct sockaddr*)&saddr,sizeof(saddr));
	if(iRet != 0){
		perror("bind");
		exit(-1);
	}

	//3.侦听客户端的连接
	iRet = listen(sid,5);
	if(iRet != 0){
		perror("listen");
		exit(-1);
	}

	//4.接受客户端的连接
	int addrsize = sizeof(struct sockaddr_in);
	int pid = accept(sid,(struct sockaddr *)&caddr,&addrsize);
	if(pid < 0){
		perror("accept");
		exit(-1);
	}

	char buffer[1024] = {0};
	int len = -1;
	
	while(1){
		bzero(buffer,sizeof(buffer));

		//5.接收客户端发送的消息
		len = recv(pid,buffer,sizeof(buffer),0);
		if(len < 0)
		{
			perror("recv");
			exit(-1);
		}
		else 
		{
			buffer[len] = 0;//加结束符
			printf("Receive: %s\n",buffer);
		}

		bzero(buffer,sizeof(buffer));
		strcpy(buffer, "Welcome to access the server!");
		
		//6.发送消息给客户端
		len = send(pid,buffer,strlen(buffer),0);
		if(len < 0){
			perror("send");
			exit(-1);
		}
	}
	close(pid);
	close(sid);

	return 0;
}

2.2 基于多线程的并发服务器示例程序(编译：gcc server.c -o server lpthread)

#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<stdio.h>
#include<string.h>
#include<unistd.h>
#include<pthread.h>
#include<stdlib.h>

#define PORT 10000

void thread_process(const int * socketid)
{
	int cid = *socketid;
	char buffer[1024] = {0};
	int iLen = -1;
	
	while(1)
	{
		bzero(buffer,sizeof(buffer));
		
		//5.接收客户端发来的消息
		iLen = recv(cid,buffer,sizeof(buffer),0);
		if(iLen < 0)
		{
			perror("recv");
			exit(-1);
		}
		else 
		{
			buffer[iLen] = 0;//加结束符
			printf("Receive: %s\n",buffer);
		}
		
		bzero(buffer,sizeof(buffer));
		strcpy(buffer, "Welcome to access the server!");
		//6.发送消息给客户端
		iLen = send(cid,buffer,strlen(buffer),0);
		if(iLen < 0)
		{
			perror("send");
			exit(-1);
		}
	}
	
	close(cid); 
}

int main()
{
	//1.创建套接字
	int sid = socket(AF_INET,SOCK_STREAM,0);
	if(sid < 0 ){
		perror("socket");
		exit(-1);
	}

	struct sockaddr_in saddr,caddr;
	saddr.sin_family = AF_INET;
	saddr.sin_port = htons(PORT);
	saddr.sin_addr.s_addr = INADDR_ANY;

	//2.绑定本地地址和端口号
	int iRet = bind(sid,(struct sockaddr*)&saddr,sizeof(saddr));
	if(iRet != 0){
		perror("bind");
		exit(-1);
	}
	
	//3.侦听客户端的连接
	iRet = listen(sid,5);
	if(iRet != 0){
		perror("listen");
		exit(-1);
	}

	while(1)
	{
		//4.接受客户端的连接
		int addrsize = sizeof(struct sockaddr_in);
		int cid = accept(sid,(struct sockaddr *)&caddr,&addrsize);
		if(cid < 0)
		{
			perror("accept");
			exit(-1);
		}
		
		//创建线程
		pthread_t tid;
		int err = pthread_create(&tid,NULL,(void*)thread_process,(void*)&cid);
		if (err != 0)
		{
			printf("can't create thread: %s\n", strerror(err));
			exit(-1);
		}        
	}
	
	//7.关闭套接字
	close(sid);
}

3. 客户端示例程序

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

#define PORT 10000
#define IP "192.168.1.101"

int main(){
	//1.创建套接字
	int cid = socket(AF_INET,SOCK_STREAM,0);
	if(cid < 0 ){
		perror("socket");
		exit(-1);
	}
	
	struct sockaddr_in saddr;
	saddr.sin_family = AF_INET;
	saddr.sin_port = htons(PORT);
	saddr.sin_addr.s_addr = inet_addr(IP);

	//2.连接服务器
	int iRet = connect(cid,(struct sockaddr*)&saddr,sizeof(struct sockaddr));
	if(iRet < 0 ){
		perror("connect");
		exit(-1);
	}
	
	char buffer[100] = {0};
	int len = -1;

	while(strncmp(buffer,"quit",4) != 0){
		bzero(buffer,sizeof(buffer));
		fgets(buffer,1024,stdin);
		
		//3.发送消息给服务器
		len = send(cid,buffer,strlen(buffer),0);
		if(len < 0)
		{
			perror("send");
			exit(-1);
		}
		
		
		bzero(buffer,sizeof(buffer));
		
		//4.接收服务器的回应
		len = recv(cid,buffer,sizeof(buffer),0);
		if(len < 0)
		{
			perror("recv");
			exit(-1);
		}
		else 
		{
			buffer[len] = 0;//加结束符
			printf("\nReceive: %s\n",buffer);
		}		
	}
	
	//5.关闭套接字
	close(cid);
}