#include <bios/netdev.h>#include <bios/checksum.h>#include <bios/buflist.h>#include <bios/string.h>#include <bios/ip.h>#include <bios/if_ether.h>#include <bios/stdio.h>#ifndef DEBUG#define debug_printf(x...)#endifstatic u32 ip_pkt_no;char *in_ntoa(u32 addr){	static char buffer[16];	sprintf(buffer, "%d.%d.%d.%d",		addr & 255,		(addr >> 8) & 255,		(addr >> 16) & 255,		(addr >> 24) & 255);	return buffer;}static unsigned short ip_check(struct iphdr *ip){	unsigned int check, length = ip->ip_ihl * 4;	check = ~checksum(ip, length, 0);	if (check == 0)		check = -1;	return htons(check);}int ip_send(struct netdev *nd, int protocol, u32 from, u32 to, struct buflist *data){	u8 hwto[6], *dest;	struct buflist bl, *blp;	struct iphdr ip;	int size = 0;	for (blp = data; blp; blp = blp->next)		size += blp->size;	ip.ip_ver    = 4;	ip.ip_ihl    = 5;	ip.ip_tos    = 0;	ip.ip_len    = htons(sizeof(ip) + size);	ip.ip_id     = htons(ip_pkt_no);	ip.ip_frag   = 0;	ip.ip_ttl    = 0x40;	ip.ip_proto  = protocol;	ip.ip_check  = 0;	ip.ip_source = from;	ip.ip_dest   = to;	ip.ip_check  = ip_check(&ip);	ip_pkt_no += 1;	bl.data = &ip;	bl.size = sizeof(ip);	bl.next = data;	if (to == INADDR_ANY)		dest = nd->hw_broadcast;	else if (!arp_lookup(nd, to, hwto))		dest = hwto;	else		return -1;		blp = nd->trans->header(nd, dest, ETH_P_IP, &bl);	return blp ? nd->trans->send(nd, blp) : -1;}int ip_recv(struct netdev *nd, int protocol, u32 from, u32 to, u8 *buffer){	u8 ip_buffer[1584];	struct iphdr *ip = (struct iphdr *)ip_buffer;	int bytes, hdrlen;	bytes = nd->trans->recv(nd, ETH_P_IP, ip_buffer);	if (bytes == 0)		return 0;	if (ip->ip_ver != 4 || ip->ip_ihl < 5) {		debug_printf("wrong IP version/header length\n");		return 0;	}	hdrlen = ip->ip_ihl * 4;	if (checksum(ip, hdrlen, 0) != 0xffff) {		debug_printf("bad IP checksum\n");		return 0;	}	if (ip->ip_proto != protocol) {		debug_printf("wrong protocol\n");		return 0;	}	if (from != INADDR_ANY && from != ip->ip_source) {		debug_printf("wrong source address\n");		return 0;	}	if (to != INADDR_ANY && to != ip->ip_dest) {		debug_printf("wrong destination address\n");		return 0;	}	bytes -= hdrlen;	memcpy(buffer, ip_buffer + hdrlen, bytes);	return bytes;}