apconn.c

本人在做一快无线网络通信的代码

/*APConn.c*/
#include <string.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <unistd.h>
#include <signal.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <net/if_arp.h>

#define MYPORT 8700
#define HERPORT 5500
#define HEPORT 8000
#define BUF_LEN 100
#define STACONN 1
#define RECONN 2
#define APCONN 3
#define MAXINTERFACES 16
typedef struct
{
	int code;
	struct in_addr ipofsta_eth1;
	struct in_addr netofsta_eth0;
	struct in_addr ipofap;
}ConnMsg;

typedef struct
{
	int code;
	struct in_addr ipofsta_eth1;
	struct in_addr ipofsta_eth0;
}BCMsg;

void init_daemon(void)
{
	int pid;
	int i;

	if(pid=fork())
		exit(0);	//是父进程，结束父进程
	else if(pid< 0)
		exit(1);	//fork失败，退出
	//是第一子进程，后台继续执行
	setsid();		//第一子进程成为新的会话组长和进程组长
	//并与控制终端分离
	if(pid=fork())
		exit(0);	//是第一子进程，结束第一子进程
	else if(pid< 0)
		exit(1);	//fork失败，退出
	//是第二子进程，继续
	//第二子进程不再是会话组长

	for(i=0;i< NOFILE;++i)//关闭打开的文件描述符
	close(i);
	chdir("/tmp/yaffs");	//改变工作目录到/tmp
	umask(0);		//重设文件创建掩模
	return;
} 

char *getgw();

int getroute(char *argv[])
{
	FILE *PROC;
	int i;
	char line[512];
	int ifnum = 0;
	char destip[16], gwip[16];
	
	strcpy(destip, argv[0]);
	strcpy(gwip, argv[1]);
	PROC = fopen("/proc/net/route","r");
	fgets(line,sizeof(line),PROC); 
	while (!feof(PROC)) 
	{
		char iface[8];
		unsigned int dest, gateway, mask;
		int i,field = 0;
		char *fields[10];
		char *byteoffset;
		
		fgets(line,sizeof(line),PROC);
		for (i=0;i<sizeof(line);i++) 
		{
			

			fields[field++] = line + i;
			if ((byteoffset = strchr(line + i,'\t')) == NULL)	
				i = sizeof(line);// No more fields to parse 
			else if (field > 9)
				// Don't need any more fields 
				// Why 9 and not 8?  Well, because during the 9th loop, we figure the end of the 8th field 
			i = sizeof(line);
			else{
				*byteoffset = '\0';
				i = byteoffset - line;
			}
		}		
		//sscanf(fields[0],"%s",iface);
		sscanf(fields[1],"%x",&dest);
		sscanf(fields[2],"%x",&gateway);
		//sscanf(fields[7],"%x",&mask);
		if(!strcmp((char*)inet_ntoa(*((struct in_addr *)&dest)),destip))  
		{	
			if(!strcmp((char *)inet_ntoa(*((struct in_addr *)&gateway)),gwip))
			{
				fclose(PROC);
				return 0; //the same host router has been built
			}
			if(strcmp((char *)inet_ntoa(*((struct in_addr *)&gateway)),gwip))
			{
				fclose(PROC);
				return 1; //have different host router
			}
		}
		
	}
	fclose(PROC);
	return -1; //no host router now
}

struct in_addr getip(char argv[4])
{
	int fd = 0, intrface, retn=0;
	struct ifreq buf[MAXINTERFACES];
	struct arpreq arp;
	struct ifconf ifc;
	int ifnum;
	char * StaIP[2];
	struct in_addr tmpaddr;
	int flag = 0;
	bzero(&tmpaddr, sizeof(tmpaddr));
	while(flag == 0){
	   if((fd = socket(AF_INET, SOCK_DGRAM, 0)) >=0)
	   {
		ifc.ifc_len = sizeof(buf);
		ifc.ifc_buf = (caddr_t)buf;
		if(!ioctl(fd, SIOCGIFCONF, (char *)&ifc))
		{
			intrface = ifc.ifc_len/sizeof(struct ifreq);
			ifnum = (int)intrface - 1;
			
			while (intrface --> 0)
			{
				
				if(!(ioctl(fd, SIOCGIFADDR, (char*)&buf[intrface])))
				{
					if(!strcmp(buf[intrface].ifr_name, argv))
					{
						bzero(&tmpaddr, sizeof(tmpaddr));
						tmpaddr = ((struct sockaddr_in*)(&buf[intrface].ifr_addr))->sin_addr;
						//puts("eth1:");puts((char *)inet_ntoa(tmpaddr)); 
						
					}
				}
			}
		}
	   }
	   close(fd);
	   if(strcmp((char *)inet_ntoa(tmpaddr), "0.0.0.0"))
	  	flag = 1;	 
           
	   
	}
	//puts((char*)inet_ntoa(tmpaddr));puts("\n");
	
	 return tmpaddr;
}

unsigned long setStaRoute(BCMsg tmpMsg)
{
	struct in_addr inaddr1,inaddr2;
	char *net_sta, *ip_sta;
	unsigned long netmask,sta_net;
	char command[1024];
	char * route[2];
	char ipofsta[16], netofsta[16];

	int flag = 0;
	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=tmpMsg.ipofsta_eth0.s_addr& netmask;
	
	inaddr1.s_addr= sta_net;
	inaddr2=tmpMsg.ipofsta_eth1;
	
	strcpy(ipofsta, (char*)inet_ntoa(inaddr1));
	strcpy(netofsta, (char*)inet_ntoa(inaddr2));
	route[0] = ipofsta;
	route[1] = netofsta;
	//puts(route[0]);puts(route[1]);
	flag = getroute(route);
	if(flag == 1 || flag == -1)
	{
		bzero(&command, sizeof(command));
		sprintf(command,"route add -net %s netmask 255.255.255.0 gw %s dev eth1", route[0], route[1]);
		system(command);
		puts(command);
	}
	return sta_net;
	
}
int main(int argc,char*argv[])
{
	int sockfd,sock;
	struct sockaddr_in saddr;		/*my address info*/
	struct sockaddr_in faddr;		/*connector's addr info*/
	struct sockaddr_in haddr;		/*发给代理时使用*/
	struct sockaddr_in gaddr;		/*返回给STA时使用*/
	int addr_len,numbytes;
	char buf[BUF_LEN];
	char syscmd[100];
	int fbroadcast=1;
	int conn = STACONN;
	int aconn = APCONN;
	char *GetwayAddr;
	BCMsg SMsg;
	ConnMsg connMsg;
	unsigned long netofsta;
	FILE *fp;
	struct in_addr ip_eth1;

	//init_daemon();//初始化为Daemon
	ip_eth1 = getip("eth1");
	sprintf(syscmd, "ifconfig tunl0 %s netmask 255.255.255.255 pointopoint 192.168.3.4", (char*)inet_ntoa(ip_eth1));
	system(syscmd);
	//puts(syscmd);
	syscmd = NULL;
	sprintf(syscmd, "route del -host 192.168.3.4");
	system(syscmd);

	GetwayAddr = "0";
	//bzero(&saddr,sizeof(struct sockaddr_in));
	saddr.sin_family = AF_INET;
	saddr.sin_port = htons(MYPORT);	/*short,network byte order*/	
	saddr.sin_addr.s_addr = htonl(INADDR_ANY);	/*auto fill with my ip*/
	
	//bzero(&gaddr,sizeof(struct sockaddr_in));
	gaddr.sin_family = AF_INET;
	gaddr.sin_port = htons(HERPORT);	/*short,network byte order*/	

	bzero(&haddr,sizeof(struct sockaddr_in));
	haddr.sin_family = AF_INET;
	haddr.sin_port = htons(HEPORT);

	if ((sock = socket(AF_INET,SOCK_DGRAM,0))==-1){
		fprintf(fp, "socket call error");
		exit(1);
	}
	if ((sockfd = socket(AF_INET,SOCK_DGRAM,0)) ==-1){
		fprintf(fp, "socket call error");
		exit(1);
	}
	//setsockopt(sockfd,SOL_SOCKET,SO_BROADCAST,&fbroadcast,sizeof(int));
	
//	printf("IP=%s,Port=%d\n",inet_ntoa(saddr.sin_addr),ntohs(saddr.sin_port));
	
	if (bind(sockfd,(struct sockaddr*)&saddr, sizeof(saddr)) == -1){		
		fprintf(fp, "bind");
		exit(1);
	}
	addr_len = sizeof(struct sockaddr_in);
	while(1)
	{
		if((fp=fopen("apconn.log","a")) == NULL) continue;
		if ((numbytes=recvfrom(sockfd,buf,BUF_LEN,0,(struct sockaddr *)&faddr,&addr_len)) == -1){
			fprintf(fp,"recvfrom");
			continue;
		}
		printf("got packet from %s\npacket is %d bytes long\n",inet_ntoa(faddr.sin_addr),numbytes);
		memcpy(&SMsg.code,buf,sizeof(int));//get code from buf
		if(SMsg.code != conn) continue;//not STA's info,go on recv
		memcpy(&SMsg, buf, sizeof(BCMsg));
		//memcpy(&SMsg.ipofsta_eth1,buf+sizeof(SMsg.code),sizeof(SMsg.ipofsta_eth1)); 
		//puts((char*)inet_ntoa(SMsg.ipofsta_eth1));//get ip from buf
		//memcpy(&SMsg.ipofsta_eth0, buf+ sizeof(SMsg.ipofsta_eth1), sizeof(SMsg.ipofsta_eth0));
		//puts((char*)inet_ntoa(SMsg.ipofsta_eth0));
		netofsta = setStaRoute(SMsg);//puts(netofsta);

		
		//fprintf(fp,"%s\n", inet_ntoa(SMsg.ipOfSTA));
		gaddr.sin_addr.s_addr = faddr.sin_addr.s_addr;	//设置发送的目标地址	
		
		if(( numbytes = sendto(sockfd,0,0,0,(struct sockaddr *)&gaddr,addr_len))==-1){
			fprintf(fp,"AP sendto STA");
			continue;
		}
		printf("send packet to %s\n",inet_ntoa(gaddr.sin_addr));
		//fprintf(fp,"send packet to %s\n",inet_ntoa(gaddr.sin_addr));
		//AP send info to STA 

		bzero(buf,sizeof(buf));			//buf set zero
		connMsg.code=APCONN;	//puts("point2");printf("%d\n",connMsg.code);
		connMsg.ipofsta_eth1 = SMsg.ipofsta_eth1;	//puts("point3");puts((char*)inet_ntoa(connMsg.ipofsta_eth1));		//set code ,is AP to STA info
		connMsg.netofsta_eth0.s_addr= netofsta;//puts((char*)inet_ntoa(connMsg.netofsta_eth0));	//puts("point4");puts((char*)inet_ntoa(connMsg.netofsta_eth0));
		connMsg.ipofap = getip("eth0");	//puts("point5");puts((char*)inet_ntoa(connMsg.ipofap));
		memcpy(buf,&connMsg,sizeof(ConnMsg));
		
		//set buf	
		GetwayAddr = getgw();		//取得代理的目的地址,即本身的网关
		haddr.sin_addr.s_addr = inet_addr(GetwayAddr);//puts("point8");
		if(( numbytes = sendto(sock,buf,100,0,(struct sockaddr *)&haddr,addr_len))==-1){
			fprintf(fp,"AP sendto Agent");
			continue;
		}
		printf("send packet to %s\n",inet_ntoa(haddr.sin_addr));	//ap to agent with info code '2',ip of STA
		//fprintf(fp,"send packet to %s\n",inet_ntoa(haddr.sin_addr));
		fclose(fp);
		usleep(200000);
	}
	close(sockfd);
	close(sock);
}

char *getgw()
{
FILE *PROC;
char  *def;
char line[512];

def = (char*)malloc(15);
PROC = fopen("/proc/net/route","r"); 	//puts("point62");
//fgets(line,sizeof(line),PROC);
while (!feof(PROC)) 
{  
	char iface[8];
	unsigned int dest, gateway, mask;
	int i,field = 0;
	char *fields[10];
	
	fgets(line,sizeof(line),PROC);
	for (i=0;i<sizeof(line);i++) {
		char *byteoffset;

		fields[field++] = line + i;
		if ((byteoffset = strchr(line + i,'\t')) == NULL)
			// No more fields to parse 
			i = sizeof(line);
		else if (field > 9)
			// Don't need any more fields 
			// Why 9 and not 8?  Well, because during the 9th loop, we figure the end of the 8th field 
			i = sizeof(line);
			else {
				*byteoffset = '\0';
				i = byteoffset - line;
				}
		}		
		
			sscanf(fields[2],"%x",&gateway);
			if(gateway!=0x00000000){
		  	memcpy(def,(char*)inet_ntoa(*((struct in_addr *)&gateway)),15);
	
			}	
}
	
fclose(PROC);
if (def==NULL) 
	return 0;
else
	return(def);
}