arp.c

来自「ADS下的bios工程」· C语言 代码 · 共 147 行

#include <bios/types.h>
#include <bios/netdev.h>
#include <bios/string.h>
#include <bios/time.h>

#undef DEBUG_S3C4_ARP
#ifdef DEBUG_S3C4_ARP
	#define DEBUG_ARP(fmt, args...) printf("%s-%s()[%d]: " fmt, __FILE__, __FUNCTION__, __LINE__, args)
#else
	#define DEBUG_ARP(fmt, args...)
#endif

static u32	cached_ip;
static u8	cached_hw[8];

int arp_send(struct netdev *nd, u32 ip_addr);
int arp_lookup(struct netdev *nd, u32 addr, u8 *eth_addr);
int arp_reply(struct netdev *nd, u32 ip_addr);


int arp_send(struct netdev *nd, u32 ip_addr)
{
	static struct arphdr ar;
	static struct buflist bl, *blp;

	{
		int k=10000;
		while(k--);
	}

	bl.data = &ar;
	bl.size = sizeof(ar);
	bl.next = NULL;

	memzero(&ar, sizeof(ar));

	ar.ar_hrd = htons(1);		/* ARPHRD_ETHER */
	ar.ar_pro = htons(ETH_P_IP);
	ar.ar_hln = nd->hw_addr_len;
	ar.ar_pln = sizeof(ip_addr);
	ar.ar_op  = htons(1);		/* ARPOP_REQUEST */
	memcpy(ar.ar_sha, nd->hw_addr, nd->hw_addr_len);
	memcpy(ar.ar_sip, &nd->ip_addr, sizeof(nd->ip_addr));
	memcpy(ar.ar_tip, &ip_addr, sizeof(ip_addr));

      
	blp = nd->eth_header(nd, nd->hw_broadcast, ETH_P_ARP, &bl);
       
        DEBUG_ARP("\n%s","->");

	return blp ? nd->eth_send(nd, blp) : -1;
}

static int arp_reply_valid(struct netdev *nd, u32 ip_addr, struct arphdr *ar)
{
	int valid;

	valid = ar->ar_hrd == htons(1);			/* ARPHRD_ETHER */
	valid = valid && ar->ar_pro == htons(ETH_P_IP);
	valid = valid && ar->ar_hln == nd->hw_addr_len;
	valid = valid && ar->ar_pln == sizeof(ip_addr);
	valid = valid && ar->ar_op == htons(2);		/* ARPOP_REPLY */
	valid = valid && memeq(ar->ar_tha, nd->hw_addr, nd->hw_addr_len);
	valid = valid && memeq(ar->ar_tip, &nd->ip_addr, sizeof(nd->ip_addr));
	valid = valid && memeq(ar->ar_sip, &ip_addr, sizeof(ip_addr));

	return valid;
}

int arp_lookup(struct netdev *nd, u32 addr, u8 *eth_addr)
{
	int retries = 15, timeout = 25;

	while(addr != cached_ip && retries) {
		static struct arphdr *ar;
		static char buffer[1024];
		int bytes;
		int next_try;

		ar = (struct arphdr *)buffer;

                DEBUG_ARP("\n%s","->");
		arp_send(nd, addr);

		next_try = centisecs + timeout;
		timeout = timeout * 2;
		if (timeout > 500)
			timeout = 500;

		do {
                        DEBUG_ARP("\n%s","->");
			bytes = nd->eth_recv(nd, ETH_P_ARP, buffer);
                        DEBUG_ARP("BYTES(%d)\n",bytes);

			if (bytes >= sizeof(*ar) && arp_reply_valid(nd, addr, ar))
				break;
			bytes = 0;
		} while (centisecs < next_try);

		retries -= 1;
                
		if (!bytes)
			continue;

		cached_ip = addr;
		memcpy(cached_hw, ar->ar_sha, ar->ar_hln);
	}

	if (addr == cached_ip) {
		memcpy(eth_addr, cached_hw, nd->hw_addr_len);
                DEBUG_ARP("CACHED_HW(%x)\n",cached_hw);
		return 0;
	}
  
	return 1;
}


int arp_reply(struct netdev *nd, u32 ip_addr)
{
	static struct arphdr ar;
	static struct buflist bl, *blp;


	bl.data = &ar;
	bl.size = sizeof(ar);
	bl.next = NULL;

	memzero(&ar, sizeof(ar));

	ar.ar_hrd = htons(1);		/* ARPHRD_ETHER */
	ar.ar_pro = htons(ETH_P_IP);
	ar.ar_hln = nd->hw_addr_len;
	ar.ar_pln = sizeof(ip_addr);
	ar.ar_op  = htons(2);		/* ARPOP_REQUEST */
	memcpy(ar.ar_sha, nd->hw_addr, nd->hw_addr_len);
	memcpy(ar.ar_tha, nd->tha_addr, nd->hw_addr_len);
	memcpy(ar.ar_sip, &nd->ip_addr, sizeof(nd->ip_addr));
	memcpy(ar.ar_tip, &ip_addr, sizeof(ip_addr));


	blp = nd->eth_header(nd, nd->tha_addr, ETH_P_ARP, &bl);

        DEBUG_ARP("\n%s","->");
	return blp ? nd->eth_send(nd, blp) : -1;
}