icmp.c

ARM2410+DM9000的驱动与寄存器配置代码

#include "type.h"
#include "icmp.h"
#include "arp.h"


/*******************************/
static u16_t ip_len = 0;
static u8_t *ip_outbuf = NULL;
/******/
void ip_init(void)
{
	ip_len = 0;
	ip_outbuf = NULL;
}
// header hdr
/*
   //IP header
 __packed struct ip_hdr{
	u8_t vhl, tos;
	u16_t len, ipid, ipoffset;
	u8_t ttl, proto;
	u16_t ipchksum;
	u32_t srcipaddr, destipaddr;
};  
*/
u32_t ip_input(u8_t *buf, u16_t len)
{
	struct ip_hdr *hdr = (struct ip_hdr*)buf;

	if(hdr->vhl != 0x45) //IP version and header length
		return -1;

	len = HTONS(hdr->len);

	//Check the fragment flag. 
	if(hdr->ipoffset != 0)
		return -1;

	//Check for ICMP packet
	if(hdr->proto == PROTO_ICMP)
		return icmp_input(buf, len);

	return 0;
}

u32_t ip_send_packet(u8_t *buf, u16_t len)
{
	ip_len = len;
	ip_outbuf = buf;
	return 0;
}

u16_t ip_getout_packet(u8_t **buf)
{
	u16_t len = ip_len;
	ip_len = 0;
	*buf = ip_outbuf;
	ip_outbuf = NULL;
	return len;
}

/***********************/
/***********************/
   //ICMP (echo) header.
	/* __packed struct icmp_hdr{
	struct ip_hdr iphdr;
	u8_t type, icode;
	u16_t icmpchksum;
	u16_t id, seqno;  
      }; */
u32_t icmp_input(u8_t *buf, u16_t len)
{
	u32_t tmp;
	struct icmp_hdr *hdr = (struct icmp_hdr*)buf;

	if(hdr->type != ICMP_ECHO)
		return -1;
	hdr->type = ICMP_ECHO_REPLY;

	if(hdr->icmpchksum >= HTONS(0xffff - (ICMP_ECHO << 8)))
		hdr->icmpchksum += HTONS(ICMP_ECHO << 8) + 1;
	else
		hdr->icmpchksum += HTONS(ICMP_ECHO << 8);

	//Swap IP addresses. 
	tmp = hdr->iphdr.destipaddr;
	hdr->iphdr.destipaddr = hdr->iphdr.srcipaddr;
	hdr->iphdr.srcipaddr = tmp;

	ip_send_packet(buf, len);

	return 0;
}