servers/inet/generic/ip_read.c
/*
ip_read.c

Copyright 1995 Philip Homburg
*/

#include "inet.h"
#include "buf.h"
#include "clock.h"
#include "event.h"
#include "type.h"

#include "assert.h"
#include "icmp_lib.h"
#include "io.h"
#include "ip.h"
#include "ip_int.h"
#include "ipr.h"
#include "sr.h"

THIS_FILE

static ip_ass_t *find_ass_ent ARGS(( ip_port_t *ip_port, u16_t id,
	ipproto_t proto, ipaddr_t src, ipaddr_t dst ));
static acc_t *merge_frags ARGS(( acc_t *first, acc_t *second ));
static int ip_frag_chk ARGS(( acc_t *pack ));
static acc_t *reassemble ARGS(( ip_port_t *ip_port, acc_t *pack, 
	ip_hdr_t *ip_hdr ));
static void route_packets ARGS(( event_t *ev, ev_arg_t ev_arg ));
static int broadcast_dst ARGS(( ip_port_t *ip_port, ipaddr_t dest ));

int ip_read(int fd, size_t count)
{
	ip_fd_t *ip_fd;
	acc_t *pack;

	ip_fd= &ip_fd_table[fd];
	if (!(ip_fd->if_flags & IFF_OPTSET))
	{
		return (*ip_fd->if_put_userdata)(ip_fd->if_srfd, EBADMODE,
			(acc_t *)0, FALSE);
	}

	ip_fd->if_rd_count= count;

	ip_fd->if_flags |= IFF_READ_IP;
	if (ip_fd->if_rdbuf_head)
	{
		if (get_time() <= ip_fd->if_exp_time)
		{
			pack= ip_fd->if_rdbuf_head;
			ip_fd->if_rdbuf_head= pack->acc_ext_link;
			ip_packet2user (ip_fd, pack, ip_fd->if_exp_time,
				bf_bufsize(pack));
			assert(!(ip_fd->if_flags & IFF_READ_IP));
			return NW_OK;
		}
		while (ip_fd->if_rdbuf_head)
		{
			pack= ip_fd->if_rdbuf_head;
			ip_fd->if_rdbuf_head= pack->acc_ext_link;
			bf_afree(pack);
		}
	}
	return NW_SUSPEND;
}

static acc_t *reassemble (ip_port, pack, pack_hdr)
ip_port_t *ip_port;
acc_t *pack;
ip_hdr_t *pack_hdr;
{
	ip_ass_t *ass_ent;
	size_t pack_offset, tmp_offset;
	u16_t pack_flags_fragoff;
	acc_t *prev_acc, *curr_acc, *next_acc, *head_acc, *tmp_acc;
	ip_hdr_t *tmp_hdr;
	time_t first_time;

	ass_ent= find_ass_ent (ip_port, pack_hdr->ih_id,
		pack_hdr->ih_proto, pack_hdr->ih_src, pack_hdr->ih_dst);

	pack_flags_fragoff= ntohs(pack_hdr->ih_flags_fragoff);
	pack_offset= (pack_flags_fragoff & IH_FRAGOFF_MASK)*8;
	pack->acc_ext_link= NULL;

	head_acc= ass_ent->ia_frags;
	ass_ent->ia_frags= NULL;
	if (head_acc == NULL)
	{
		ass_ent->ia_frags= pack;
		return NULL;
	}

	prev_acc= NULL;
	curr_acc= NULL;
	next_acc= head_acc;

	while(next_acc)
	{
		tmp_hdr= (ip_hdr_t *)ptr2acc_data(next_acc);
		tmp_offset= (ntohs(tmp_hdr->ih_flags_fragoff) &
			IH_FRAGOFF_MASK)*8;

		if (pack_offset < tmp_offset)
			break;

		prev_acc= curr_acc;
		curr_acc= next_acc;
		next_acc= next_acc->acc_ext_link;
	}
	if (curr_acc == NULL)
	{
		assert(prev_acc == NULL);
		assert(next_acc != NULL);

		curr_acc= merge_frags(pack, next_acc);
		head_acc= curr_acc;
	}
	else
	{
		curr_acc= merge_frags(curr_acc, pack);
		if (next_acc != NULL)
			curr_acc= merge_frags(curr_acc, next_acc);
		if (prev_acc != NULL)
			prev_acc->acc_ext_link= curr_acc;
		else
			head_acc= curr_acc;
	}
	ass_ent->ia_frags= head_acc;

	pack= ass_ent->ia_frags;
	pack_hdr= (ip_hdr_t *)ptr2acc_data(pack);
	pack_flags_fragoff= ntohs(pack_hdr->ih_flags_fragoff);

	if (!(pack_flags_fragoff & (IH_FRAGOFF_MASK|IH_MORE_FRAGS)))
		/* it's now a complete packet */
	{
		first_time= ass_ent->ia_first_time;

		ass_ent->ia_frags= 0;
		ass_ent->ia_first_time= 0;

		while (pack->acc_ext_link)
		{
			tmp_acc= pack->acc_ext_link;
			pack->acc_ext_link= tmp_acc->acc_ext_link;
			bf_afree(tmp_acc);
		}
		if ((ass_ent->ia_min_ttl) * HZ + first_time <
			get_time())
		{
			if (broadcast_dst(ip_port, pack_hdr->ih_dst))
			{
				DBLOCK(1, printf(
	"ip_read'reassemble: reassembly timeout for broadcast packet\n"););
				bf_afree(pack); pack= NULL;
				return NULL;
			}
			icmp_snd_time_exceeded(ip_port->ip_port, pack,
				ICMP_FRAG_REASSEM);
		}
		else
			return pack;
	}
	return NULL;
}

static acc_t *merge_frags (first, second)
acc_t *first, *second;
{
	ip_hdr_t *first_hdr, *second_hdr;
	size_t first_hdr_size, second_hdr_size, first_datasize, second_datasize,
		first_offset, second_offset;
	acc_t *cut_second, *tmp_acc;

	if (!second)
	{
		first->acc_ext_link= NULL;
		return first;
	}

assert (first->acc_length >= IP_MIN_HDR_SIZE);
assert (second->acc_length >= IP_MIN_HDR_SIZE);

	first_hdr= (ip_hdr_t *)ptr2acc_data(first);
	first_offset= (ntohs(first_hdr->ih_flags_fragoff) &
		IH_FRAGOFF_MASK) * 8;
	first_hdr_size= (first_hdr->ih_vers_ihl & IH_IHL_MASK) * 4;
	first_datasize= ntohs(first_hdr->ih_length) - first_hdr_size;

	second_hdr= (ip_hdr_t *)ptr2acc_data(second);
	second_offset= (ntohs(second_hdr->ih_flags_fragoff) &
		IH_FRAGOFF_MASK) * 8;
	second_hdr_size= (second_hdr->ih_vers_ihl & IH_IHL_MASK) * 4;
	second_datasize= ntohs(second_hdr->ih_length) - second_hdr_size;

	assert (first_hdr_size + first_datasize == bf_bufsize(first));
	assert (second_hdr_size + second_datasize == bf_bufsize(second));
	assert (second_offset >= first_offset);

	if (second_offset > first_offset+first_datasize)
	{
		DBLOCK(1, printf("ip fragments out of order\n"));
		first->acc_ext_link= second;
		return first;
	}

	if (second_offset + second_datasize <= first_offset +
		first_datasize)
	{
		/* May cause problems if we try to merge. */
		bf_afree(first);
		return second;
	}

	if (!(second_hdr->ih_flags_fragoff & HTONS(IH_MORE_FRAGS)))
		first_hdr->ih_flags_fragoff &= ~HTONS(IH_MORE_FRAGS);

	second_datasize= second_offset+second_datasize-(first_offset+
		first_datasize);
	cut_second= bf_cut(second, second_hdr_size + first_offset+
		first_datasize-second_offset, second_datasize);
	tmp_acc= second->acc_ext_link;
	bf_afree(second);
	second= tmp_acc;

	first_datasize += second_datasize;
	first_hdr->ih_length= htons(first_hdr_size + first_datasize);

	first= bf_append (first, cut_second);
	first->acc_ext_link= second;

assert (first_hdr_size + first_datasize == bf_bufsize(first));

	return first;
}

static ip_ass_t *find_ass_ent ARGS(( ip_port_t *ip_port, u16_t id,
	ipproto_t proto, ipaddr_t src, ipaddr_t dst ))
{
	ip_ass_t *new_ass_ent, *tmp_ass_ent;
	int i;
	acc_t *tmp_acc, *curr_acc;

	new_ass_ent= 0;

	for (i=0, tmp_ass_ent= ip_ass_table; i<IP_ASS_NR; i++,
		tmp_ass_ent++)
	{
		if (!tmp_ass_ent->ia_frags && tmp_ass_ent->ia_first_time)
		{
			DBLOCK(1,
		printf("strange ip_ass entry (can be a race condition)\n"));
			continue;
		}

		if ((tmp_ass_ent->ia_srcaddr == src) &&
			(tmp_ass_ent->ia_dstaddr == dst) &&
			(tmp_ass_ent->ia_proto == proto) &&
			(tmp_ass_ent->ia_id == id) &&
			(tmp_ass_ent->ia_port == ip_port))
		{
			return tmp_ass_ent;
		}
		if (!new_ass_ent || tmp_ass_ent->ia_first_time <
			new_ass_ent->ia_first_time)
		{
			new_ass_ent= tmp_ass_ent;
		}
	}

	if (new_ass_ent->ia_frags)
	{
		DBLOCK(2, printf("old frags id= %u, proto= %u, src= ",
			ntohs(new_ass_ent->ia_id),
			new_ass_ent->ia_proto);
			writeIpAddr(new_ass_ent->ia_srcaddr); printf(" dst= ");
			writeIpAddr(new_ass_ent->ia_dstaddr); printf(": ");
			ip_print_frags(new_ass_ent->ia_frags); printf("\n"));
		curr_acc= new_ass_ent->ia_frags->acc_ext_link;
		while (curr_acc)
		{
			tmp_acc= curr_acc->acc_ext_link;
			bf_afree(curr_acc);
			curr_acc= tmp_acc;
		}
		curr_acc= new_ass_ent->ia_frags;
		new_ass_ent->ia_frags= 0;
		if (broadcast_dst(ip_port, new_ass_ent->ia_dstaddr))
		{
			DBLOCK(1, printf(
	"ip_read'find_ass_ent: reassembly timeout for broadcast packet\n"));
			bf_afree(curr_acc); curr_acc= NULL;
		}
		else
		{
			icmp_snd_time_exceeded(ip_port->ip_port,
				curr_acc, ICMP_FRAG_REASSEM);
		}
	}
	new_ass_ent->ia_min_ttl= IP_MAX_TTL;
	new_ass_ent->ia_port= ip_port;
	new_ass_ent->ia_first_time= get_time();
	new_ass_ent->ia_srcaddr= src;
	new_ass_ent->ia_dstaddr= dst;
	new_ass_ent->ia_proto= proto;
	new_ass_ent->ia_id= id;

	return new_ass_ent;
}

static int ip_frag_chk(pack)
acc_t *pack;
{
	ip_hdr_t *ip_hdr;
	int hdr_len;

	if (pack->acc_length < sizeof(ip_hdr_t))
	{
		DBLOCK(1, printf("wrong length\n"));
		return FALSE;
	}

	ip_hdr= (ip_hdr_t *)ptr2acc_data(pack);

	hdr_len= (ip_hdr->ih_vers_ihl & IH_IHL_MASK) * 4;
	if (pack->acc_length < hdr_len)
	{
		DBLOCK(1, printf("wrong length\n"));

		return FALSE;
	}

	if (((ip_hdr->ih_vers_ihl >> 4) & IH_VERSION_MASK) !=
		IP_VERSION)
	{
		DBLOCK(1, printf("wrong version (ih_vers_ihl=0x%x)\n",
			ip_hdr->ih_vers_ihl));
		return FALSE;
	}
	if (ntohs(ip_hdr->ih_length) != bf_bufsize(pack))
	{
		DBLOCK(1, printf("wrong size\n"));

		return FALSE;
	}
	if ((u16_t)~oneC_sum(0, (u16_t *)ip_hdr, hdr_len))
	{
		DBLOCK(1, printf("packet with wrong checksum (= %x)\n", 
			(u16_t)~oneC_sum(0, (u16_t *)ip_hdr, hdr_len)));
		return FALSE;
	}
	if (hdr_len>IP_MIN_HDR_SIZE && ip_chk_hdropt((u8_t *)
		(ptr2acc_data(pack) + IP_MIN_HDR_SIZE),
		hdr_len-IP_MIN_HDR_SIZE))
	{
		DBLOCK(1, printf("packet with wrong options\n"));
		return FALSE;
	}
	return TRUE;
}

int ip_sel_read (ip_fd_t *ip_fd)
{
	acc_t *pack;

	if (!(ip_fd->if_flags & IFF_OPTSET))
		return 1;	/* Read will not block */

	if (ip_fd->if_rdbuf_head)
	{
		if (get_time() <= ip_fd->if_exp_time)
			return 1;

		while (ip_fd->if_rdbuf_head)
		{
			pack= ip_fd->if_rdbuf_head;
			ip_fd->if_rdbuf_head= pack->acc_ext_link;
			bf_afree(pack);
		}
	}
	return 0;
}

void ip_packet2user (ip_fd, pack, exp_time, data_len)
ip_fd_t *ip_fd;
acc_t *pack;
time_t exp_time;
size_t data_len;
{
	acc_t *tmp_pack;
	ip_hdr_t *ip_hdr;
	int result, ip_hdr_len;
	size_t transf_size;

	assert (ip_fd->if_flags & IFF_INUSE);
	if (!(ip_fd->if_flags & IFF_READ_IP))
	{
		if (pack->acc_linkC != 1)
		{
			tmp_pack= bf_dupacc(pack);
			bf_afree(pack);
			pack= tmp_pack;
			tmp_pack= NULL;
		}
		pack->acc_ext_link= NULL;
		if (ip_fd->if_rdbuf_head == NULL)
		{
			ip_fd->if_rdbuf_head= pack;
			ip_fd->if_exp_time= exp_time;
		}
		else
			ip_fd->if_rdbuf_tail->acc_ext_link= pack;
		ip_fd->if_rdbuf_tail= pack;

		if (ip_fd->if_flags & IFF_SEL_READ)
		{
			ip_fd->if_flags &= ~IFF_SEL_READ;
			if (ip_fd->if_select_res)
				ip_fd->if_select_res(ip_fd->if_srfd,
					SR_SELECT_READ);
			else
				printf("ip_packet2user: no select_res\n");
		}
		return;
	}

	assert (pack->acc_length >= IP_MIN_HDR_SIZE);
	ip_hdr= (ip_hdr_t *)ptr2acc_data(pack);

	if (ip_fd->if_ipopt.nwio_flags & NWIO_RWDATONLY)
	{
		ip_hdr_len= (ip_hdr->ih_vers_ihl & IH_IHL_MASK) * 4;

		assert (data_len > ip_hdr_len);
		data_len -= ip_hdr_len;
		pack= bf_delhead(pack, ip_hdr_len);
	}

	if (data_len > ip_fd->if_rd_count)
	{
		tmp_pack= bf_cut (pack, 0, ip_fd->if_rd_count);
		bf_afree(pack);
		pack= tmp_pack;
		transf_size= ip_fd->if_rd_count;
	}
	else
		transf_size= data_len;

	if (ip_fd->if_put_pkt)
	{
		(*ip_fd->if_put_pkt)(ip_fd->if_srfd, pack, transf_size);
		return;
	}

	result= (*ip_fd->if_put_userdata)(ip_fd->if_srfd,
		(size_t)0, pack, FALSE);
	if (result >= 0)
	{
		if (data_len > transf_size)
			result= EPACKSIZE;
		else
			result= transf_size;
	}

	ip_fd->if_flags &= ~IFF_READ_IP;
	result= (*ip_fd->if_put_userdata)(ip_fd->if_srfd, result,
			(acc_t *)0, FALSE);
	assert (result >= 0);
}

void ip_port_arrive (ip_port, pack, ip_hdr)
ip_port_t *ip_port;
acc_t *pack;
ip_hdr_t *ip_hdr;
{
	ip_fd_t *ip_fd, *first_fd, *share_fd;
	unsigned long ip_pack_stat;
	unsigned size;
	int i;
	int hash, proto;
	time_t exp_time;

	assert (pack->acc_linkC>0);
	assert (pack->acc_length >= IP_MIN_HDR_SIZE);

	if (ntohs(ip_hdr->ih_flags_fragoff) & (IH_FRAGOFF_MASK|IH_MORE_FRAGS))
	{
		pack= reassemble (ip_port, pack, ip_hdr);
		if (!pack)
			return;
		assert (pack->acc_length >= IP_MIN_HDR_SIZE);
		ip_hdr= (ip_hdr_t *)ptr2acc_data(pack);
		assert (!(ntohs(ip_hdr->ih_flags_fragoff) &
			(IH_FRAGOFF_MASK|IH_MORE_FRAGS)));
	}
	size= ntohs(ip_hdr->ih_length);
	if (size > bf_bufsize(pack))
	{
		/* Should discard packet */
		assert(0);
		bf_afree(pack); pack= NULL;
		return;
	}

	exp_time= get_time() + (ip_hdr->ih_ttl+1) * HZ;

	if (ip_hdr->ih_dst == ip_port->ip_ipaddr)
		ip_pack_stat= NWIO_EN_LOC;
	else
		ip_pack_stat= NWIO_EN_BROAD;

	proto= ip_hdr->ih_proto;
	hash= proto & (IP_PROTO_HASH_NR-1);

	first_fd= NULL;
	for (i= 0; i<2; i++)
	{
		share_fd= NULL;

		ip_fd= (i == 0) ? ip_port->ip_proto_any :
			ip_port->ip_proto[hash];
		for (; ip_fd; ip_fd= ip_fd->if_proto_next)
		{
			if (i && ip_fd->if_ipopt.nwio_proto != proto)
				continue;
			if (!(ip_fd->if_ipopt.nwio_flags & ip_pack_stat))
				continue;
			if ((ip_fd->if_ipopt.nwio_flags & NWIO_REMSPEC) &&
				ip_hdr->ih_src != ip_fd->if_ipopt.nwio_rem)
			{
				continue;
			}
			if ((ip_fd->if_ipopt.nwio_flags & NWIO_ACC_MASK) ==
				NWIO_SHARED)
			{
				if (!share_fd)
				{
					share_fd= ip_fd;
					continue;
				}
				if (!ip_fd->if_rdbuf_head)
					share_fd= ip_fd;
				continue;
			}
			if (!first_fd)
			{
				first_fd= ip_fd;
				continue;
			}
			pack->acc_linkC++;
			ip_packet2user(ip_fd, pack, exp_time, size);

		}
		if (share_fd)
		{
			pack->acc_linkC++;
			ip_packet2user(share_fd, pack, exp_time, size);
		}
	}
	if (first_fd)
	{
		if (first_fd->if_put_pkt &&
			(first_fd->if_flags & IFF_READ_IP) &&
			!(first_fd->if_ipopt.nwio_flags & NWIO_RWDATONLY))
		{
			(*first_fd->if_put_pkt)(first_fd->if_srfd, pack,
				size);
		}
		else
			ip_packet2user(first_fd, pack, exp_time, size);
	}
	else
	{
		if (ip_pack_stat == NWIO_EN_LOC)
		{
			DBLOCK(0x01,
			printf("ip_port_arrive: dropping packet for proto %d\n",
				proto));
		}
		else
		{
			DBLOCK(0x20, printf("dropping packet for proto %d\n",
				proto));
		}
		bf_afree(pack);
	}
}

void ip_arrived(ip_port, pack)
ip_port_t *ip_port;
acc_t *pack;
{
	ip_hdr_t *ip_hdr;
	ipaddr_t dest;
	int ip_frag_len, ip_hdr_len, highbyte;
	size_t pack_size;
	acc_t *tmp_pack, *hdr_pack;
	ev_arg_t ev_arg;

	pack_size= bf_bufsize(pack);

	if (pack_size < IP_MIN_HDR_SIZE)
	{
		DBLOCK(1, printf("wrong acc_length\n"));
		bf_afree(pack);
		return;
	}
	pack= bf_align(pack, IP_MIN_HDR_SIZE, 4);
	pack= bf_packIffLess(pack, IP_MIN_HDR_SIZE);
assert (pack->acc_length >= IP_MIN_HDR_SIZE);

	ip_hdr= (ip_hdr_t *)ptr2acc_data(pack);
	ip_hdr_len= (ip_hdr->ih_vers_ihl & IH_IHL_MASK) << 2;
	if (ip_hdr_len>IP_MIN_HDR_SIZE)
	{
		pack= bf_packIffLess(pack, ip_hdr_len);
		ip_hdr= (ip_hdr_t *)ptr2acc_data(pack);
	}
	ip_frag_len= ntohs(ip_hdr->ih_length);
	if (ip_frag_len != pack_size)
	{
		if (pack_size < ip_frag_len)
		{
			/* Sent ICMP? */
			DBLOCK(1, printf("wrong acc_length\n"));
			bf_afree(pack);
			return;
		}
		assert(ip_frag_len<pack_size);
		tmp_pack= pack;
		pack= bf_cut(tmp_pack, 0, ip_frag_len);
		bf_afree(tmp_pack);
		pack_size= ip_frag_len;
	}

	if (!ip_frag_chk(pack))
	{
		DBLOCK(1, printf("fragment not allright\n"));
		bf_afree(pack);
		return;
	}

	/* Decide about local delivery or routing. Local delivery can happen
	 * when the destination is the local ip address, or one of the 
	 * broadcast addresses and the packet happens to be delivered 
	 * point-to-point.
	 */

	dest= ip_hdr->ih_dst;

	if (dest == ip_port->ip_ipaddr)
	{
		ip_port_arrive (ip_port, pack, ip_hdr);
		return;
	}
	if (broadcast_dst(ip_port, dest))
	{
		ip_port_arrive (ip_port, pack, ip_hdr);
		return;
	}

	if (pack->acc_linkC != 1 || pack->acc_buffer->buf_linkC != 1)
	{
		/* Get a private copy of the IP header */
		hdr_pack= bf_memreq(ip_hdr_len);
		memcpy(ptr2acc_data(hdr_pack), ip_hdr, ip_hdr_len);
		pack= bf_delhead(pack, ip_hdr_len);
		hdr_pack->acc_next= pack;
		pack= hdr_pack; hdr_pack= NULL;
		ip_hdr= (ip_hdr_t *)ptr2acc_data(pack);
	}
	assert(pack->acc_linkC == 1);
	assert(pack->acc_buffer->buf_linkC == 1);

	/* Try to decrement the ttl field with one. */
	if (ip_hdr->ih_ttl < 2)
	{
		icmp_snd_time_exceeded(ip_port->ip_port, pack,
			ICMP_TTL_EXC);
		return;
	}
	ip_hdr->ih_ttl--;
	ip_hdr_chksum(ip_hdr, ip_hdr_len);

	/* Avoid routing to bad destinations. */
	highbyte= ntohl(dest) >> 24;
	if (highbyte == 0 || highbyte == 127 ||
		(highbyte == 169 && (((ntohl(dest) >> 16) & 0xff) == 254)) ||
		highbyte >= 0xe0)
	{
		/* Bogus destination address */
		bf_afree(pack);
		return;
	}

	/* Further processing from an event handler */
	if (pack->acc_linkC != 1)
	{
		tmp_pack= bf_dupacc(pack);
		bf_afree(pack);
		pack= tmp_pack;
		tmp_pack= NULL;
	}
	pack->acc_ext_link= NULL;
	if (ip_port->ip_routeq_head)
	{
		ip_port->ip_routeq_tail->acc_ext_link= pack;
		ip_port->ip_routeq_tail= pack;
		return;
	}

	ip_port->ip_routeq_head= pack;
	ip_port->ip_routeq_tail= pack;
	ev_arg.ev_ptr= ip_port;
	ev_enqueue(&ip_port->ip_routeq_event, route_packets, ev_arg);
}

void ip_arrived_broadcast(ip_port, pack)
ip_port_t *ip_port;
acc_t *pack;
{
	ip_hdr_t *ip_hdr;
	int ip_frag_len, ip_hdr_len;
	size_t pack_size;
	acc_t *tmp_pack;

	pack_size= bf_bufsize(pack);

	if (pack_size < IP_MIN_HDR_SIZE)
	{
		DBLOCK(1, printf("wrong acc_length\n"));
		bf_afree(pack);
		return;
	}
	pack= bf_align(pack, IP_MIN_HDR_SIZE, 4);
	pack= bf_packIffLess(pack, IP_MIN_HDR_SIZE);
assert (pack->acc_length >= IP_MIN_HDR_SIZE);

	ip_hdr= (ip_hdr_t *)ptr2acc_data(pack);

	DIFBLOCK(0x20, (ip_hdr->ih_dst & HTONL(0xf0000000)) == HTONL(0xe0000000),
		printf("got multicast packet\n"));

	ip_hdr_len= (ip_hdr->ih_vers_ihl & IH_IHL_MASK) << 2;
	if (ip_hdr_len>IP_MIN_HDR_SIZE)
	{
		pack= bf_align(pack, IP_MIN_HDR_SIZE, 4);
		pack= bf_packIffLess(pack, ip_hdr_len);
		ip_hdr= (ip_hdr_t *)ptr2acc_data(pack);
	}
	ip_frag_len= ntohs(ip_hdr->ih_length);
	if (ip_frag_len<pack_size)
	{
		tmp_pack= pack;
		pack= bf_cut(tmp_pack, 0, ip_frag_len);
		bf_afree(tmp_pack);
	}

	if (!ip_frag_chk(pack))
	{
		DBLOCK(1, printf("fragment not allright\n"));
		bf_afree(pack);
		return;
	}

	if (!broadcast_dst(ip_port, ip_hdr->ih_dst))
	{
#if 0
		printf(
		"ip[%d]: broadcast packet for ip-nonbroadcast addr, src=",
			ip_port->ip_port);
		writeIpAddr(ip_hdr->ih_src);
		printf(" dst=");
		writeIpAddr(ip_hdr->ih_dst);
		printf("\n");
#endif
		bf_afree(pack);
		return;
	}

	ip_port_arrive (ip_port, pack, ip_hdr);
}

static void route_packets(ev, ev_arg)
event_t *ev;
ev_arg_t ev_arg;
{
	ip_port_t *ip_port;
	ipaddr_t dest;
	acc_t *pack;
	iroute_t *iroute;
	ip_port_t *next_port;
	int r, type;
	ip_hdr_t *ip_hdr;
	size_t req_mtu;

	ip_port= ev_arg.ev_ptr;
	assert(&ip_port->ip_routeq_event == ev);

	while (pack= ip_port->ip_routeq_head, pack != NULL)
	{
		ip_port->ip_routeq_head= pack->acc_ext_link;

		ip_hdr= (ip_hdr_t *)ptr2acc_data(pack);
		dest= ip_hdr->ih_dst;

		iroute= iroute_frag(ip_port->ip_port, dest);
		if (iroute == NULL || iroute->irt_dist == IRTD_UNREACHABLE)
		{
			/* Also unreachable */
			/* Finding out if we send a network unreachable is too
			 * much trouble.
			 */
			if (iroute == NULL)
			{
				printf("ip[%d]: no route to ",
					ip_port-ip_port_table);
				writeIpAddr(dest);
				printf("\n");
			}
			icmp_snd_unreachable(ip_port->ip_port, pack,
				ICMP_HOST_UNRCH);
			continue;
		}
		next_port= &ip_port_table[iroute->irt_port];

		if (ip_hdr->ih_flags_fragoff & HTONS(IH_DONT_FRAG))
		{
			req_mtu= bf_bufsize(pack);
			if (req_mtu > next_port->ip_mtu ||
				(iroute->irt_mtu && req_mtu>iroute->irt_mtu))
			{
				icmp_snd_mtu(ip_port->ip_port, pack,
					next_port->ip_mtu);
				continue;
			}
		}

		if (next_port != ip_port)
		{
			if (iroute->irt_gateway != 0)
			{
				/* Just send the packet to the next gateway */
				pack->acc_linkC++; /* Extra ref for ICMP */
				r= next_port->ip_dev_send(next_port,
					iroute->irt_gateway,
					pack, IP_LT_NORMAL);
				if (r == EHOSTUNREACH)
				{
					printf("ip[%d]: gw ",
						ip_port-ip_port_table);
					writeIpAddr(iroute->irt_gateway);
					printf(" on ip[%d] is down for dest ",
						next_port-ip_port_table);
					writeIpAddr(dest);
					printf("\n");
					icmp_snd_unreachable(next_port-
						ip_port_table, pack,
						ICMP_HOST_UNRCH);
					pack= NULL;
				}
				else
				{
					assert(r == 0);
					bf_afree(pack); pack= NULL;
				}
				continue;
			}
			/* The packet is for the attached network. Special
			 * addresses are the ip address of the interface and
			 * net.0 if no IP_42BSD_BCAST.
			 */
			if (dest == next_port->ip_ipaddr)
			{
				ip_port_arrive (next_port, pack, ip_hdr);
				continue;
			}
			if (dest == iroute->irt_dest)
			{
				/* Never forward obsolete directed broadcasts */
#if IP_42BSD_BCAST && 0
				type= IP_LT_BROADCAST;
#else
				/* Bogus destination address */
				DBLOCK(1, printf(
			"ip[%d]: dropping old-fashioned directed broadcast ",
						ip_port-ip_port_table);
					writeIpAddr(dest);
					printf("\n"););
				icmp_snd_unreachable(next_port-ip_port_table,
					pack, ICMP_HOST_UNRCH);
				continue;
#endif
			}
			else if (dest == (iroute->irt_dest |
				~iroute->irt_subnetmask))
			{
				if (!ip_forward_directed_bcast)
				{
					/* Do not forward directed broadcasts */
					DBLOCK(1, printf(
					"ip[%d]: dropping directed broadcast ",
							ip_port-ip_port_table);
						writeIpAddr(dest);
						printf("\n"););
					icmp_snd_unreachable(next_port-
						ip_port_table, pack,
						ICMP_HOST_UNRCH);
					continue;
				}
				else
					type= IP_LT_BROADCAST;
			}
			else
				type= IP_LT_NORMAL;

			/* Just send the packet to it's destination */
			pack->acc_linkC++; /* Extra ref for ICMP */
			r= next_port->ip_dev_send(next_port, dest, pack, type);
			if (r == EHOSTUNREACH)
			{
				DBLOCK(1, printf("ip[%d]: next hop ",
					ip_port-ip_port_table);
					writeIpAddr(dest);
					printf(" on ip[%d] is down\n",
					next_port-ip_port_table););
				icmp_snd_unreachable(next_port-ip_port_table,
					pack, ICMP_HOST_UNRCH);
				pack= NULL;
			}
			else
			{
				assert(r == 0 || (printf("r = %d\n", r), 0));
				bf_afree(pack); pack= NULL;
			}
			continue;
		}

		/* Now we know that the packet should be routed over the same
		 * network as it came from. If there is a next hop gateway,
		 * we can send the packet to that gateway and send a redirect
		 * ICMP to the sender if the sender is on the attached
		 * network. If there is no gateway complain.
		 */
		if (iroute->irt_gateway == 0)
		{
			printf("ip_arrived: packet should not be here, src=");
			writeIpAddr(ip_hdr->ih_src);
			printf(" dst=");
			writeIpAddr(ip_hdr->ih_dst);
			printf("\n");
			bf_afree(pack);
			continue;
		}
		if (((ip_hdr->ih_src ^ ip_port->ip_ipaddr) &
			ip_port->ip_subnetmask) == 0)
		{
			/* Finding out if we can send a network redirect
			 * instead of a host redirect is too much trouble.
			 */
			pack->acc_linkC++;
			icmp_snd_redirect(ip_port->ip_port, pack,
				ICMP_REDIRECT_HOST, iroute->irt_gateway);
		}
		else
		{
			printf("ip_arrived: packet is wrongly routed, src=");
			writeIpAddr(ip_hdr->ih_src);
			printf(" dst=");
			writeIpAddr(ip_hdr->ih_dst);
			printf("\n");
			printf("in port %d, output %d, dest net ",
				ip_port->ip_port, 
				iroute->irt_port);
			writeIpAddr(iroute->irt_dest);
			printf("/");
			writeIpAddr(iroute->irt_subnetmask);
			printf(" next hop ");
			writeIpAddr(iroute->irt_gateway);
			printf("\n");
			bf_afree(pack);
			continue;
		}
		/* No code for unreachable ICMPs here. The sender should
		 * process the ICMP redirect and figure it out.
		 */
		ip_port->ip_dev_send(ip_port, iroute->irt_gateway, pack,
			IP_LT_NORMAL);
	}
}

static int broadcast_dst(ip_port, dest)
ip_port_t *ip_port;
ipaddr_t dest;
{
	ipaddr_t my_ipaddr, netmask, classmask;

	/* Treat class D (multicast) address as broadcasts. */
	if ((dest & HTONL(0xF0000000)) == HTONL(0xE0000000))
	{
		return 1;
	}

	/* Accept without complaint if netmask not yet configured. */
	if (!(ip_port->ip_flags & IPF_NETMASKSET))
	{
		return 1;
	}
	/* Two possibilities, 0 (iff IP_42BSD_BCAST) and -1 */
	if (dest == HTONL((ipaddr_t)-1))
		return 1;
#if IP_42BSD_BCAST
	if (dest == HTONL((ipaddr_t)0))
		return 1;
#endif
	netmask= ip_port->ip_subnetmask;
	my_ipaddr= ip_port->ip_ipaddr;

	if (((my_ipaddr ^ dest) & netmask) != 0)
	{
		classmask= ip_port->ip_classfulmask;

		/* Not a subnet broadcast, maybe a classful broadcast */
		if (((my_ipaddr ^ dest) & classmask) != 0)
		{
			return 0;
		}
		/* Two possibilities, net.0 (iff IP_42BSD_BCAST) and net.-1 */
		if ((dest & ~classmask) == ~classmask)
		{
			return 1;
		}
#if IP_42BSD_BCAST
		if ((dest & ~classmask) == 0)
			return 1;
#endif
		return 0;
	}

	if (!(ip_port->ip_flags & IPF_SUBNET_BCAST))
		return 0;	/* No subnet broadcasts on this network */

	/* Two possibilities, subnet.0 (iff IP_42BSD_BCAST) and subnet.-1 */
	if ((dest & ~netmask) == ~netmask)
		return 1;
#if IP_42BSD_BCAST
	if ((dest & ~netmask) == 0)
		return 1;
#endif
	return 0;
}

void ip_process_loopb(ev, arg)
event_t *ev;
ev_arg_t arg;
{
	ip_port_t *ip_port;
	acc_t *pack;

	ip_port= arg.ev_ptr;
	assert(ev == &ip_port->ip_loopb_event);

	while(pack= ip_port->ip_loopb_head, pack != NULL)
	{
		ip_port->ip_loopb_head= pack->acc_ext_link;
		ip_arrived(ip_port, pack);
	}
}

/*
 * $PchId: ip_read.c,v 1.33 2005/06/28 14:18:50 philip Exp $
 */
