gendnspacket.c

我的本科生毕业设计

#include "genDNSPacket.h"

void genDNSPacket(char *addr,char *DNSsendBuff) //url is the DNS server ip or address and here we can delete
{
	memset(DNSsendBuff,'\0',sizeof(DNSsendBuff));

	pDNSHDR pDnsHdr = (pDNSHDR)malloc(sizeof(DNSHDR));
	pQUERYHDR pQueryHdr = (pQUERYHDR)malloc(sizeof(QUERYHDR));

	pDnsHdr->id = htons(0x0000);
	pDnsHdr->flags = htons(0x0100);
	pDnsHdr->questNum = htons(0x0001);
	pDnsHdr->answerNum = htons(0x0000);
	pDnsHdr->authorNum = htons(0x0000);
	pDnsHdr->additionNum = htons(0x0000);

	memcpy(DNSsendBuff,pDnsHdr,sizeof(DNSHDR));

	char *name = (char *)malloc(17 *sizeof(char)); // 3www4xjtu3edu2cn0
	char num;
	char *url;
	
	int cur = 0;
	num = 0x03;
	url = "www";
	memcpy(name + cur,&num,sizeof(num));
	cur += sizeof(num);
	memcpy(name+ cur,url,strlen(url));
	cur += strlen(url);

	num = 0x04;
	url = "xjtu";
	memcpy(name + cur,&num,sizeof(num));
	cur += sizeof(num);
	memcpy(name + cur,url,strlen(url));
	cur += strlen(url);

	num = 0x03;
	url = "edu";
	memcpy(name + cur,&num,sizeof(num));
	cur += sizeof(num);
	memcpy(name + cur,url,strlen(url));
	cur += strlen(url);

	num = 0x02;
	url = "cn";
	memcpy(name + cur,&num,sizeof(num));
	cur += sizeof(num);
	memcpy(name + cur,url,strlen(url));
	cur += strlen(url);

	num = 0x00;
	memcpy(name + cur,&num,sizeof(num));

	memcpy(DNSsendBuff + sizeof(DNSHDR),name,17);

	pQueryHdr->type = htons(0x0001);
	pQueryHdr->class = htons(0x0001);

	memcpy(DNSsendBuff + sizeof(DNSHDR) + 17,pQueryHdr,sizeof(QUERYHDR));
}