icmp.c

本软件是ARMSYS44B0-P开发板的自举程序（BOIS）

/****************************************************************
 *		ARMSYS7 S3C44B0X developer's notes						*  
 ****************************************************************

 1. 2005.5.17::
 
 ***************************************************************/

#include "..\inc\config.h"
#include "..\inc\utils.h"
#include "..\inc\tftp\skbuff.h"
#include "..\inc\tftp\eth.h"
#include "..\inc\tftp\ip.h"
#include "..\inc\tftp\icmp.h"

#ifdef	TFTP_DOWNLOAD_SUPPORT

static unsigned long client_ip;

static int icmp_send_echo(struct sk_buff *skb)
{
	struct icmphdr *icmp_hdr, *icmp_echo;	
	unsigned int tmp, sum, i, cnt;		
			
	cnt = skb->len;		
	if(cnt%2)
		cnt++;		
				
	icmp_hdr = (struct icmphdr *)(skb->data);
	skb = alloc_skb(ETH_FRAME_LEN);
	ip_skb_reserve(skb);		//reserve for eth and ip stack	
	icmp_echo = (struct icmphdr *)skb_put(skb, cnt);	
	
	icmp_echo->type  = 0;
	icmp_echo->code  = 0;	
	sum = 0;			
	for(i=2; i<cnt/2; i++)
	{	
		tmp = *((unsigned short *)(&icmp_hdr->type)+i);
		*((unsigned short *)(&icmp_echo->type)+i) = tmp;
		sum += tmp;				
	}
	i = sum>>16;
	icmp_echo->check = 0xffffu-(sum&0xffff)-i;			
	ip_send(skb, client_ip, ICMP);

	return 0;
}

static int icmp_rcv_echo(struct sk_buff *skb)
{
	client_ip = ip_get_source_ip(skb);
		
	icmp_send_echo(skb);
	
	return 0;
}

int icmp_rcv_packet(struct sk_buff *skb)
{
	struct icmphdr *icmp_hdr = (struct icmphdr *)(skb->data);
	
	switch(icmp_hdr->type)
	{
		case 8:
		icmp_rcv_echo(skb);
	}
	
	return 0;
}

#endif