#include <sys/types.h>
#include <arpa/inet.h>

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>

#define	RSS_KEYSIZE	40

static uint8_t rss_key[RSS_KEYSIZE] = {
	0x6d, 0x5a, 0x6d, 0x5a, 0x6d, 0x5a, 0x6d, 0x5a,
	0x6d, 0x5a, 0x6d, 0x5a, 0x6d, 0x5a, 0x6d, 0x5a,
	0x6d, 0x5a, 0x6d, 0x5a, 0x6d, 0x5a, 0x6d, 0x5a,
	0x6d, 0x5a, 0x6d, 0x5a, 0x6d, 0x5a, 0x6d, 0x5a,
	0x6d, 0x5a, 0x6d, 0x5a, 0x6d, 0x5a, 0x6d, 0x5a,
};

static uint32_t
toeplitz_hash(unsigned int keylen, const uint8_t *key, unsigned int datalen,
    const uint8_t *data)
{
	uint32_t hash = 0, v;
	unsigned int i, b;

	/* XXXRW: Perhaps an assertion about key length vs. data length? */

	v = (key[0] << 24) + (key[1] << 16) + (key[2] << 8) + key[3];
	for (i = 0; i < datalen; i++) {
		for (b = 0; b < 8; b++) {
			if (data[i] & (1 << (7 - b)))
				hash ^= v;
			v <<= 1;
			if ((i + 4) < RSS_KEYSIZE &&
			    (key[i + 4] & (1 << (7 - b))))
				v |= 1;
		}
	}
	return (hash);
}

static uint32_t
rss_hash(unsigned int datalen, const uint8_t *data)
{

	return (toeplitz_hash(sizeof(rss_key), rss_key, datalen, data));
}

static uint32_t
rss_hash_ip4_4tuple(in_addr_t src, uint16_t srcport, in_addr_t dst,
    uint16_t dstport)
{
	uint8_t data[sizeof(src) + sizeof(dst) + sizeof(srcport) +
	    sizeof(dstport)];
	unsigned int datalen;

	datalen = 0;
	bcopy(&src, &data[datalen], sizeof(src));
	datalen += sizeof(src);
	bcopy(&dst, &data[datalen], sizeof(dst));
	datalen += sizeof(dst);
	bcopy(&srcport, &data[datalen], sizeof(srcport));
	datalen += sizeof(srcport);
	bcopy(&dstport, &data[datalen], sizeof(dstport));
	datalen += sizeof(dstport);

	return (rss_hash(datalen, data));
}

int
main(int argc, char *argv[])
{
	in_addr_t src, dst;
	uint16_t srcport, dstport;
	int val;
	char *p;

	if (argc != 3)
		exit(1);

	printf("[%s] [%s]\n", argv[1], argv[2]);

	p = strchr(argv[1], ':');
	assert(p != NULL);
	*p = '\0';
	src = inet_addr(argv[1]);
	val = atoi(p + 1);
	assert(val >= 0 && val <= 65535);
	srcport = (uint16_t)val;

	p = strchr(argv[2], ':');
	assert(p != NULL);
	*p = '\0';
	dst = inet_addr(argv[2]);
	val = atoi(p + 1);
	assert(val >= 0 && val <= 65535);
	dstport = (uint16_t)val;

	printf("%u\n", rss_hash_ip4_4tuple(src, srcport, dst, dstport) & 0x3);
	printf("%u\n", rss_hash_ip4_4tuple(ntohl(src), ntohs(srcport),
	    ntohl(dst), ntohs(dstport)) & 0x3);

	return (0);
}