linux应用程序_1_文本浏览器_9_网络打印_1_TCP基本知识和例程

linux应用程序_1_文本浏览器_9_网络打印_1_TCP基本知识和例程

客户端：在网络程序中，主动和外面的程序通信

服务端：被动的等待外面的程序来和自己通讯

TCP(Transfer Control Protocol)传输控制协议是一种面向连接的协议， 当我们的网络程序使用这个协议的时候，网络可以保证我们的客户端和服务端的连接是可靠的，安全的。出现丢包现象时，会自动重连

基本调用：

int socket(int domain, int type,int protocol)

int bind(int sockfd, struct sockaddr *my_addr, int addrlen)

int listen(int sockfd,int backlog)

int accept(int sockfd, struct sockaddr *addr,int *addrlen)

int connect(int sockfd, struct sockaddr * serv_addr,int addrlen)

ssize_t send(int sockfd, const void *buf, size_t len, int flags)

ssize_t recv(int sockfd, void *buf, size_t len, int flags);

其中结构体声明有：

        struct sockaddr{
                unisgned short  as_family;
                char            sa_data[14];
        };

        struct sockaddr_in{
                unsigned short          sin_family;     
                unsigned short int      sin_port;
                struct in_addr          sin_addr;
                unsigned char           sin_zero[8];
        }

由于系统的兼容性，一般使用后者

例程：

tcp_server.c

其中signal是为了避免出现僵尸进程

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

#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <netdb.h>
#include <signal.h>



#define BACKLOG 	10
#define SERVER_PORT 8888

int main(int argc,char **argv)
{
	int iServerFd, iClientFd;
	int iRet;

	struct sockaddr_in tSocketServerAddr;
	struct sockaddr_in tSocketClientAddr;

	int iSocketAddrLen = sizeof(struct sockaddr);

	char pcBuf[1024];
	int iLen;

	int iClientNum = 0;

	signal(SIGCHLD,SIG_IGN);
	iServerFd = socket(AF_INET, SOCK_STREAM, 0);
	if(iServerFd < 0)
	{
		printf("socket error\r\n");
		return -1;
	}
	tSocketServerAddr.sin_family        = AF_INET;
	tSocketServerAddr.sin_port          = htons(SERVER_PORT);
	tSocketServerAddr.sin_addr.s_addr   = INADDR_ANY;
		
	memset(tSocketServerAddr.sin_zero, 0, 8);
	iRet = bind(iServerFd, (struct sockaddr *)&tSocketServerAddr, iSocketAddrLen);
	if(iRet < 0)
	{
		printf("bind error\r\n");
		goto error;
	}
	iRet = listen(iServerFd, BACKLOG);
	if(iRet < 0)
	{
		printf("listen error\r\n");
		return -1;
	}
	while(1)
	{
		iSocketAddrLen = sizeof(struct sockaddr);
		iClientFd = accept(iServerFd, (struct sockaddr *)&tSocketClientAddr, &iSocketAddrLen);
		if(iClientFd < 0)
		{
			printf("accept error\r\n");
			return -1;
		}
		iClientNum++;
		printf("connect with client %d %s\r\n", iClientNum, inet_ntoa(tSocketClientAddr.sin_addr));
		if(!fork())
		{
			while(1)
			{
				iLen = recv(iClientFd, pcBuf, 1023, 0);
				if(iLen <= 0)
				{
					close(iClientFd);
					goto error;
				}	
				else
				{
					pcBuf[iLen] = '\0';
					printf("get msg %s from Client %d %s\r\n", pcBuf, iClientNum, inet_ntoa(tSocketClientAddr.sin_addr));
				}
			}
		}
	}

	close(iServerFd);
	return 0;

error:
	close(iServerFd);
	return -1;
}

tcp_client.c

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

#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <netdb.h>


#define SERVER_PORT	8888

int main(int argc,char **argv)
{
	int iServerFd, iClientFd;
	int iRet;

	struct sockaddr_in tSocketServerAddr;

	int iSocketAddrLen = sizeof(struct sockaddr);

	char pcBuf[1024];
	int iLen;

	if(argc != 2)
	{
		printf("Usage : %s <server_ip>\r\n", argv[0]);
		return -1;
	}

	
	iClientFd = socket(AF_INET, SOCK_STREAM, 0);
	if(iClientFd < 0)
	{
		printf("socket error\r\n");
		return -1;
	}
	
	tSocketServerAddr.sin_family = AF_INET;
	tSocketServerAddr.sin_port   = htons(SERVER_PORT);
	if(!inet_aton(argv[1], &tSocketServerAddr.sin_addr))
	{
		printf("ivalid server_ip\r\n");
		goto error;
	}
	memset(tSocketServerAddr.sin_zero, 0, 8);

	iRet = connect(iClientFd, (struct sockaddr *)&tSocketServerAddr, sizeof(struct sockaddr));
	if(iRet < 0)
	{
		printf("connect error\r\n");
		return -1;
	}


	
	while(1)
	{
		if(!fgets(pcBuf, 1023, stdin))
		{
			printf("fgets error\r\n");
			goto error;
		}
		iLen = send(iClientFd, pcBuf, strlen(pcBuf), 0);
		if(iLen <= 0)
		{
			printf("send error\r\n");
			goto error;
		}
	}

	close(iClientFd);
	return 0;

error:
	close(iClientFd);
	return -1;
}