linux 下TCP通信例程

TCP server

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <linux/if.h>
#include <sys/ioctl.h>

#include <unistd.h>
#include <signal.h>


#include <string.h>
#include <stdio.h>
#include <stdlib.h>
	  
#define SERVER_PORT 8888
#define BACKLOG	10
/*
 * socket
 * bind
 * listen
 * accept
 * send/recv
 **/
int main(int argc, char *argv[])
{
	int iSocketServer;
	int iSocketClient;
	struct sockaddr_in tSocketServerAddr;
	struct sockaddr_in tSocketClientAddr;
	unsigned int serverport;
	
	int iAddrLen;
	unsigned char ucRecvBuf[1000];
	int iRecvLen;
	int iClientNum = -1;
	int opt = 1;
	
	int iRet;

	if(argc != 4)
	{
		printf("Usage:\n");
		printf("%s <net> <server_ip> <server_port>\n",argv[0]);
		return -1;
	}
	

	signal(SIGCHLD,SIG_IGN);
	

	
	iSocketServer =  socket(AF_INET, SOCK_STREAM, 0);
	if(iSocketServer == -1)
	{
		printf("init socket error\n");
		return -1;
	}

	/* 为套接字设置选项 */

	//一般来说，一个端口释放后会等待两分钟之后才能再被使用，SO_REUSEADDR是让端口释放后立即就可以被再次使用。
	
	iRet = setsockopt(iSocketServer, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));//地址可复用
	if(iRet < 0 )
	{
		printf("setsockopt error\n");
	}

	//绑定网卡
	struct ifreq ifr;
	strcpy(ifr.ifr_name, argv[1]);

	iRet = ioctl(iSocketServer, SIOCGIFADDR, &ifr);
	if(iRet < 0)
	{
		printf("ioctl [SIOCGIFADDR] failed");
		close(iSocketServer);
		return -1;
	}

	iRet = setsockopt(iSocketServer, SOL_SOCKET, SO_BINDTODEVICE, (char*)&ifr, sizeof(ifr));
	if(iRet < 0)
	{
		printf("setsockopt failed\n");
		close(iSocketServer);
		return -1;
	}


	//socket绑定地址
	tSocketServerAddr.sin_family 		= AF_INET;
	serverport 	= atoi(argv[3]); 
	printf("serverport:%d\n",serverport);
	tSocketClientAddr.sin_port			= htons((unsigned int)serverport);			//端口号
	
	tSocketServerAddr.sin_port	 		= htons(SERVER_PORT);	/* host to net, short */
	//tSocketServerAddr.sin_addr.s_addr 	= INADDR_ANY;			/* 检测所有ip */
	if(inet_pton(AF_INET, argv[2], &tSocketServerAddr.sin_addr) <= 0)	//可以用于IPV4或者IPV6
	{
		printf("invalid server_ip\n");
		close(iSocketServer);
		return -1;
	}
	memset(tSocketServerAddr.sin_zero, 0, 8);
	iRet =  bind(iSocketServer,  (const struct sockaddr *)&tSocketServerAddr, sizeof(struct sockaddr));
	if(iRet < 0)
	{
		printf("bind error\n");
		return -1;
	}

	//监听
	iRet = listen(iSocketServer, BACKLOG);
	if(iRet < 0)
	{
		printf("listen error\n");
		return -1;
	}
	
	while(1)
	{
		iAddrLen = sizeof(struct sockaddr);
		iSocketClient = accept(iSocketServer,(struct sockaddr *)&tSocketClientAddr, &iAddrLen);
		//if(iSocketClient >0 )
		if (-1 != iSocketClient)
		{
			iClientNum++;
			printf("get connnect from client %d: %s\n", iClientNum, inet_ntoa(tSocketClientAddr.sin_addr));
			fflush(stdout);
			if(!fork())
			{
				/* 子进程源码 */
				while(1)
				{
					//接受客户端的数据并显示出来
					iRecvLen = recv(iSocketClient, ucRecvBuf, 999, 0);
					if(iRecvLen <= 0)
					{
						close(iSocketClient);
						return -1;
					}
					else
					{
						ucRecvBuf[iRecvLen] = '\0';
						printf("Get message from client %d: %s", iClientNum, ucRecvBuf);
					}
				}
			}
		}
	}
	close(iSocketServer);
	return 0;
}

执行sudo ./server lo 127.0.0.1 8888

TCP client

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


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

	  
#define SERVER_PORT 8888
#define CLIENT_PORT 1234

/*
 * socket
 * bind  //可以选择是否绑定到ip
 * connect
 * send/recv
 **/
int main(int argc, char *argv[])
{
	struct sockaddr_in tSocketServerAddr;
	struct sockaddr_in tSocketClientAddr;	//可以用于指定IP：port去连接服务器
	int iSocketClient;
	
	unsigned int clientport;
	unsigned int serverport;
	unsigned char ucSendBuf[1000];
	int iSendLen;
	int opt = 1;
	int iRet;
	
	if(argc != 5)
	{
		printf("Usage:\n");
		printf("%s <client_ip> <client_port> <server_ip> <server_port>\n",argv[0]);
		return -1;
	}
	
	iSocketClient =  socket(AF_INET, SOCK_STREAM, 0);
	if(iSocketClient == -1)
	{
		printf("init socket error\n");
		return -1;
	}
	//设置socket选项
	iRet = setsockopt(iSocketClient, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));//地址可复用
	if(iRet < 0 )
	{
		printf("setsockopt error\n");
	}
	
	//可以用于指定IP：port去连接服务器
	tSocketClientAddr.sin_family		= AF_INET;
	clientport 	= atoi(argv[2]); 
	printf("clientport:%d\n",clientport);
	tSocketClientAddr.sin_port			= htons((unsigned int)clientport);			//端口号
	
	if(inet_pton(AF_INET, argv[1], &tSocketClientAddr.sin_addr) <= 0)	//可以用于IPV4或者IPV6
	{
		printf("invalid client_ip\n");
		close(iSocketClient);
		return -1;
	}
	memset(tSocketClientAddr.sin_zero, 0, 8);
	iRet = bind(iSocketClient, (const struct sockaddr *)&tSocketClientAddr,sizeof(struct sockaddr));
	if(iRet < 0 )
	{
		printf("bind error\n");
	}
	
	
	/* 用于连接服务器 connect */
	tSocketServerAddr.sin_family 		= AF_INET;
	serverport = atoi(argv[4]);
	tSocketServerAddr.sin_port	 		= htons(serverport);	/* host to net, short */
	if(0 == inet_aton(argv[3], &tSocketServerAddr.sin_addr))
	{
		printf("invalid server_ip\n");
		close(iSocketClient);
		return -1;
	}
	memset(tSocketServerAddr.sin_zero, 0, 8);
	iRet =  connect(iSocketClient, (const struct sockaddr *) &tSocketServerAddr,sizeof(struct sockaddr));
	if(-1 == iRet)
	{
		printf("connect error\n");
		return -1;
	}
	
	while(1)
	{
		if(fgets(ucSendBuf, 999, stdin))
		{
			//采用send或者sendto都可以。
#if 0
			iSendLen =  sendto(iSocketClient, ucSendBuf, strlen(ucSendBuf),0,
                      (const struct sockaddr *)&tSocketServerAddr, sizeof(struct sockaddr));
#else
			iSendLen = send(iSocketClient, ucSendBuf, strlen(ucSendBuf),0);
#endif
			if(iSendLen <=0 )
			{
				printf("send error\n");
				close(iSocketClient);
				return -1;
			}
		}
	}
	return 0;
}

执行./client 127.0.0.1 54321 127.0.0.1 8888