IP校验和不对..

Aweiwei_ 2014-01-30 04:43:22

关键代码..



typedef struct ip_hdr 

{

  /*unsigned char	

  			version:4,

  			ihl:4;*/



  unsigned char 	h_ver;

  unsigned char		tos;

  unsigned short	tot_len;

  unsigned short	id;

  unsigned short

  			zero:1,

			frag:1,

			more_frag:1,	

  			frag_off:13; 			

  unsigned char		ttl;

  unsigned char		protocol;

  unsigned short	checkSum;

  unsigned long		saddr;

  unsigned long		daddr;

  /*The options start here. */

}IP_HEADER;



unsigned short checkSum(unsigned char * buff, int wlen)

{

    unsigned long sum = 0;



    if (wlen) {

    	unsigned long bogus;

	 __asm__("clc\n"

		"1:\t"

		"lodsl\n\t"

		"adcl %3, %0\n\t"

		"decl %2\n\t"

		"jne 1b\n\t"

		"adcl $0, %0\n\t"

		"movl %0, %3\n\t"

		"shrl $16, %3\n\t"

		"addw %w3, %w0\n\t"

		"adcw $0, %w0"

	    : "=r" (sum), "=S" (buff), "=r" (wlen), "=a" (bogus)

	    : "0"  (sum),  "1" (buff),  "2" (wlen));

    }

    return (~sum) & 0xffff;

}



int IPGen(ip_hdr *hdr,unsigned long srcIP,unsigned long dstIP)

{

	/*hdr->version=4;

	hdr->ihl=5;//= =?*/

	hdr->h_ver=(4<<4 | sizeof(ip_hdr)/sizeof(unsigned int));

	hdr->tos=0;

	hdr->tot_len=sizeof(ip_hdr)+sizeof(tcp_hdr);

	hdr->id=0;

	hdr->zero=0;

	hdr->frag=0;

	hdr->more_frag=0;

	hdr->frag_off=0;

	hdr->ttl=64;

	hdr->protocol=IP_TCP;

	hdr->saddr=srcIP,

	hdr->daddr=dstIP;

	

	hdr->saddr=htonl(hdr->saddr);

	hdr->daddr=htonl(hdr->daddr);

	hdr->tot_len=htons(hdr->tot_len);

	

	hdr->checkSum=0;

	hdr->checkSum=checkSum((char*)hdr,sizeof(ip_hdr));

	return 0;

}