proxy.c

无线网络中

#include <sys/types.h>
#include <sys/select.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/file.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <string.h>


#define SERV_PORT 5678//the port opened for server
#define CONN_PORT 5666 //the port to recieve the connect message

#define STYLE_ConnMsg 0x03
#define MAXLEN 1024//the max length for read or write data once

/////////////////////////////////////////////////////////////////////
struct RegMsg{                          //the register message struct form proxy
	int code;
	unsigned long sta_addr;
	unsigned long regAgent_addr;
};

struct ConnMsg{
	int code;
	unsigned long sta_addr;
	unsigned long ap_addr;
};
///////////////////////////////////////////////////////////////////////
void setStaRoute(unsigned long sta,unsigned long ap);
int check_msg(char *buf);
//////////////////////////////////////////////////////////////////////
void setStaRoute(unsigned long sta,unsigned long ap)
{
	struct in_addr inaddr1,inaddr2;
	char *net_sta, *ip_ap;
	unsigned long netmask,sta_net;
	char command[1024];
	
	netmask=0;
	sta_net=0;

	memset(command,0,1024);
	memset(&inaddr1,0,sizeof(inaddr1));
	memset(&inaddr2,0,sizeof(inaddr2));
	
	netmask=0<<24|255<<16|255<<8|255;
	sta_net=sta&netmask;
	
	inaddr1.s_addr=sta_net;
	inaddr2.s_addr=ap;
	
	net_sta=(char*)inet_ntoa(inaddr1);
	ip_ap=(char*)inet_ntoa(inaddr2);	
	
	system("echo '1' > /proc/sys/net/ipv4/ip_forward");
	sprintf(command,"route add -net %s netmask 255.255.255.0 gw %s dev eth0",net_sta,ip_ap);
	system(command);
	
}
/////////////////////////////////////////////////////////////////////////////
int check_msg(char *buf)
{

	if(buf[0]==STYLE_ConnMsg)
			return 0;
	else
		return -1;
	
}
///////////////////////////////////////////////////////////////////////



int main(int argc,char ** argv)
{
	int maxfd;
	int listen_fd;
	int sock_test;
	int nonBlock;   //the variable to set socket non-blocked
	
	fd_set readset,writeset;
	int recv_len,recv_n;   
	char recvs[MAXLEN];           
	char buffer[MAXLEN];

	struct sockaddr_in serv_addr,recv_addr;
	struct sockaddr_in reg_addr;
	
	struct ConnMsg *pMsg;
	struct RegMsg regmsg;
	///////////////////////////////////////////initialize the variables
	recv_len=0;
	recv_n=0;
	
	nonBlock=1;

	memset(recvs,0,	MAXLEN);
	memset(&regmsg,0,sizeof(regmsg));

	memset(buffer,0,MAXLEN);
 
//////////////////////////////////////////////////////////////////////////
	listen_fd=socket(AF_INET,SOCK_DGRAM,0);
	
	if(listen_fd<0)
	{
		printf("socket() failed with error!\n");
		exit(1);
	}
	else
		printf("socket() success\n");

	
	serv_addr.sin_family=AF_INET;
	serv_addr.sin_addr.s_addr=htonl(INADDR_ANY);
	serv_addr.sin_port=htons(CONN_PORT);
	bzero(&(serv_addr.sin_zero),8);
	
	reg_addr.sin_family=AF_INET;
	reg_addr.sin_port=htons(SERV_PORT);
	reg_addr.sin_addr.s_addr=htonl(INADDR_ANY);
	bzero(&(reg_addr.sin_zero),8);

	sock_test=bind(listen_fd,(struct sockaddr*)&serv_addr,sizeof(struct sockaddr));

	if(sock_test<0)
	{
		printf("bind() failed with error!\n");
		exit(1);
	}
	else
		printf("bind() success\n");
	
	//set the listen socket listen_fd as nonblock socket
	ioctl(listen_fd,FIONBIO,&nonBlock);
	
	//now set the parameter of select()
	if(maxfd<listen_fd)
		maxfd=listen_fd;
	
	while(1)
	{
		FD_ZERO(&readset);
		FD_ZERO(&writeset);
		FD_SET(listen_fd,&readset);
		
		select(maxfd+1,&readset,NULL,NULL,NULL);

		if(FD_ISSET(listen_fd,&readset))
		{
  		memset(recvs,0,MAXLEN);	
  		recv_len=sizeof(recv_addr);
  		bzero(&recv_addr,sizeof(recv_addr));
  		
			recv_n=recvfrom(listen_fd,recvs,MAXLEN,0,(struct sockaddr*)&recv_addr,&recv_len);
		  if(recv_n<0)
			{
				printf("recvfrom error!\n");
				exit(1);
			}
			if(check_msg(recvs)==0)  //it is the connect message from ap
			{
				pMsg=(struct ConnMsg*)recvs;
				setStaRoute(pMsg->sta_addr,pMsg->ap_addr);
				
				regmsg.code=0x04;
				regmsg.sta_addr=pMsg->sta_addr;
				regmsg.regAgent_addr=htonl(INADDR_ANY);
				
				memcpy(buffer,&regmsg,sizeof(regmsg));
				
				sendto(listen_fd,buffer,MAXLEN,0,(struct sockaddr*)&reg_addr,sizeof(reg_addr));
				
			}
//			printf("the recv_addr is %s\n",inet_ntoa(recv_addr.sin_addr.s_addr));	
//			sendto(listen_fd,sends,strlen(sends),0,(struct sockaddr *)&recv_addr,recv_len);
		 }		 
	}
	close(listen_fd);
	return;
}