/* memory.c

   Memory-resident database... */

/*
 * Copyright (c) 1995, 1996 The Internet Software Consortium.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of The Internet Software Consortium nor the names
 *    of its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This software has been written for the Internet Software Consortium
 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
 * Enterprises.  To learn more about the Internet Software Consortium,
 * see ``http://www.vix.com/isc''.  To learn more about Vixie
 * Enterprises, see ``http://www.vix.com''.
 */

#ifndef lint
static char copyright[] =
"$Id: memory.c,v 1.3 2000/07/21 00:33:53 beck Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium.  All rights reserved.\n";
#endif /* not lint */

#include "dhcpd.h"

static struct subnet *subnets;
static struct shared_network *shared_networks;
static struct hash_table *host_hw_addr_hash;
static struct hash_table *host_uid_hash;
static struct hash_table *lease_uid_hash;
static struct hash_table *lease_ip_addr_hash;
static struct hash_table *lease_hw_addr_hash;
static struct lease *dangling_leases;

static struct hash_table *vendor_class_hash;
static struct hash_table *user_class_hash;

void enter_host (hd)
	struct host_decl *hd;
{
	struct host_decl *hp = (struct host_decl *)0;
	struct host_decl *np = (struct host_decl *)0;

	hd -> n_ipaddr = (struct host_decl *)0;

	if (hd -> interface.hlen) {
		if (!host_hw_addr_hash)
			host_hw_addr_hash = new_hash ();
		else
			hp = (struct host_decl *)
				hash_lookup (host_hw_addr_hash,
					     hd -> interface.haddr,
					     hd -> interface.hlen);

		/* If there isn't already a host decl matching this
		   address, add it to the hash table. */
		if (!hp)
			add_hash (host_hw_addr_hash,
				  hd -> interface.haddr, hd -> interface.hlen,
				  (unsigned char *)hd);
	}

	/* If there was already a host declaration for this hardware
	   address, add this one to the end of the list. */

	if (hp) {
		for (np = hp; np -> n_ipaddr; np = np -> n_ipaddr)
			;
		np -> n_ipaddr = hd;
	}

	if (hd -> group -> options [DHO_DHCP_CLIENT_IDENTIFIER]) {
		if (!tree_evaluate (hd -> group -> options
				    [DHO_DHCP_CLIENT_IDENTIFIER]))
			return;
			
		/* If there's no uid hash, make one; otherwise, see if
		   there's already an entry in the hash for this host. */
		if (!host_uid_hash) {
			host_uid_hash = new_hash ();
			hp = (struct host_decl *)0;
		} else
			hp = (struct host_decl *) hash_lookup
				(host_uid_hash,
				 hd -> group -> options
				 [DHO_DHCP_CLIENT_IDENTIFIER] -> value,
				 hd -> group -> options
				 [DHO_DHCP_CLIENT_IDENTIFIER] -> len);

		/* If there's already a host declaration for this
		   client identifier, add this one to the end of the
		   list.  Otherwise, add it to the hash table. */
		if (hp) {
			/* Don't link it in twice... */
			if (!np) {
				for (np = hp; np -> n_ipaddr;
				     np = np -> n_ipaddr)
					;
				np -> n_ipaddr = hd;
			}
		} else {
			add_hash (host_uid_hash,
				  hd -> group -> options
				  [DHO_DHCP_CLIENT_IDENTIFIER] -> value,
				  hd -> group -> options
				  [DHO_DHCP_CLIENT_IDENTIFIER] -> len,
				  (unsigned char *)hd);
		}
	}
}

struct host_decl *find_hosts_by_haddr (htype, haddr, hlen)
	int htype;
	unsigned char *haddr;
	int hlen;
{
	struct host_decl *foo;

	foo = (struct host_decl *)hash_lookup (host_hw_addr_hash,
					       haddr, hlen);
	return foo;
}

struct host_decl *find_hosts_by_uid (data, len)
	unsigned char *data;
	int len;
{
	struct host_decl *foo;

	foo = (struct host_decl *)hash_lookup (host_uid_hash, data, len);
	return foo;
}

/* More than one host_decl can be returned by find_hosts_by_haddr or
   find_hosts_by_uid, and each host_decl can have multiple addresses.
   Loop through the list of hosts, and then for each host, through the
   list of addresses, looking for an address that's in the same shared
   network as the one specified.    Store the matching address through
   the addr pointer, update the host pointer to point at the host_decl
   that matched, and return the subnet that matched. */

struct subnet *find_host_for_network (host, addr, share)
	struct host_decl **host;
	struct iaddr *addr;
	struct shared_network *share;
{
	int i;
	struct subnet *subnet;
	struct iaddr ip_address;
	struct host_decl *hp;

	for (hp = *host; hp; hp = hp -> n_ipaddr) {
		if (!hp -> fixed_addr || !tree_evaluate (hp -> fixed_addr))
			continue;
		for (i = 0; i < hp -> fixed_addr -> len; i += 4) {
			ip_address.len = 4;
			memcpy (ip_address.iabuf,
				hp -> fixed_addr -> value + i, 4);
			subnet = find_grouped_subnet (share, ip_address);
			if (subnet) {
				*addr = ip_address;
				*host = hp;
				return subnet;
			}
		}
	}
	return (struct subnet *)0;
}

void new_address_range (low, high, subnet, dynamic)
	struct iaddr low, high;
	struct subnet *subnet;
	int dynamic;
{
	struct lease *address_range, *lp, *plp;
	struct iaddr net;
	int min, max, i;
	char lowbuf [16], highbuf [16], netbuf [16];
	struct shared_network *share = subnet -> shared_network;
	struct hostent *h;
	struct in_addr ia;

	/* All subnets should have attached shared network structures. */
	if (!share) {
		strcpy (netbuf, piaddr (subnet -> net));
		error ("No shared network for network %s (%s)",
		       netbuf, piaddr (subnet -> netmask));
	}

	/* Initialize the hash table if it hasn't been done yet. */
	if (!lease_uid_hash)
		lease_uid_hash = new_hash ();
	if (!lease_ip_addr_hash)
		lease_ip_addr_hash = new_hash ();
	if (!lease_hw_addr_hash)
		lease_hw_addr_hash = new_hash ();

	/* Make sure that high and low addresses are in same subnet. */
	net = subnet_number (low, subnet -> netmask);
	if (!addr_eq (net, subnet_number (high, subnet -> netmask))) {
		strcpy (lowbuf, piaddr (low));
		strcpy (highbuf, piaddr (high));
		strcpy (netbuf, piaddr (subnet -> netmask));
		error ("Address range %s to %s, netmask %s spans %s!",
		       lowbuf, highbuf, netbuf, "multiple subnets");
	}

	/* Make sure that the addresses are on the correct subnet. */
	if (!addr_eq (net, subnet -> net)) {
		strcpy (lowbuf, piaddr (low));
		strcpy (highbuf, piaddr (high));
		strcpy (netbuf, piaddr (subnet -> netmask));
		error ("Address range %s to %s not on net %s/%s!",
		       lowbuf, highbuf, piaddr (subnet -> net), netbuf);
	}

	/* Get the high and low host addresses... */
	max = host_addr (high, subnet -> netmask);
	min = host_addr (low, subnet -> netmask);

	/* Allow range to be specified high-to-low as well as low-to-high. */
	if (min > max) {
		max = min;
		min = host_addr (high, subnet -> netmask);
	}

	/* Get a lease structure for each address in the range. */
	address_range = new_leases (max - min + 1, "new_address_range");
	if (!address_range) {
		strcpy (lowbuf, piaddr (low));
		strcpy (highbuf, piaddr (high));
		error ("No memory for address range %s-%s.", lowbuf, highbuf);
	}
	memset (address_range, 0, (sizeof *address_range) * (max - min + 1));

	/* Fill in the last lease if it hasn't been already... */
	if (!share -> last_lease) {
		share -> last_lease = &address_range [0];
	}

	/* Fill out the lease structures with some minimal information. */
	for (i = 0; i < max - min + 1; i++) {
		address_range [i].ip_addr =
			ip_addr (subnet -> net, subnet -> netmask, i + min);
		address_range [i].starts =
			address_range [i].timestamp = MIN_TIME;
		address_range [i].ends = MIN_TIME;
		address_range [i].subnet = subnet;
		address_range [i].shared_network = share;
		address_range [i].flags = dynamic ? DYNAMIC_BOOTP_OK : 0;

		memcpy (&ia, address_range [i].ip_addr.iabuf, 4);

		if (subnet -> group -> get_lease_hostnames) {
			h = gethostbyaddr ((char *)&ia, sizeof ia, AF_INET);
			if (!h)
				warn ("No hostname for %s", inet_ntoa (ia));
			else {
				address_range [i].hostname =
					malloc (strlen (h -> h_name) + 1);
				if (!address_range [i].hostname)
					error ("no memory for hostname %s.",
					       h -> h_name);
				strcpy (address_range [i].hostname,
					h -> h_name);
			}
		}

		/* Link this entry into the list. */
		address_range [i].next = share -> leases;
		address_range [i].prev = (struct lease *)0;
		share -> leases = &address_range [i];
		if (address_range [i].next)
			address_range [i].next -> prev = share -> leases;
		add_hash (lease_ip_addr_hash,
			  address_range [i].ip_addr.iabuf,
			  address_range [i].ip_addr.len,
			  (unsigned char *)&address_range [i]);
	}

	/* Find out if any dangling leases are in range... */
	plp = (struct lease *)0;
	for (lp = dangling_leases; lp; lp = lp -> next) {
		struct iaddr lnet;
		int lhost;

		lnet = subnet_number (lp -> ip_addr, subnet -> netmask);
		lhost = host_addr (lp -> ip_addr, subnet -> netmask);

		/* If it's in range, fill in the real lease structure with
		   the dangling lease's values, and remove the lease from
		   the list of dangling leases. */
		if (addr_eq (lnet, subnet -> net) &&
		    lhost >= i && lhost <= max) {
			if (plp) {
				plp -> next = lp -> next;
			} else {
				dangling_leases = lp -> next;
			}
			lp -> next = (struct lease *)0;
			address_range [lhost - i].hostname = lp -> hostname;
			address_range [lhost - i].client_hostname =
				lp -> client_hostname;
			supersede_lease (&address_range [lhost - i], lp, 0);
			free_lease (lp, "new_address_range");
		} else
			plp = lp;
	}
}

struct subnet *find_subnet (addr)
	struct iaddr addr;
{
	struct subnet *rv;

	for (rv = subnets; rv; rv = rv -> next_subnet) {
		if (addr_eq (subnet_number (addr, rv -> netmask), rv -> net))
			return rv;
	}
	return (struct subnet *)0;
}

struct subnet *find_grouped_subnet (share, addr)
	struct shared_network *share;
	struct iaddr addr;
{
	struct subnet *rv;

	for (rv = share -> subnets; rv; rv = rv -> next_sibling) {
		if (addr_eq (subnet_number (addr, rv -> netmask), rv -> net))
			return rv;
	}
	return (struct subnet *)0;
}

/* Enter a new subnet into the subnet list. */

void enter_subnet (subnet)
	struct subnet *subnet;
{
	struct subnet *scan;

	/* Check for duplicates... */
	for (scan = subnets; scan; scan = scan -> next_subnet) {
		if (addr_eq (subnet_number (subnet -> net, scan -> netmask),
			     scan -> net) ||
		    addr_eq (subnet_number (scan -> net, subnet -> netmask),
			     subnet -> net)) {
			char n1buf [16];
			int i, j;
			for (i = 0; i < 32; i++)
				if (subnet -> netmask.iabuf [3 - (i >> 3)]
				    & (1 << (i & 7)))
					break;
			for (j = 0; j < 32; j++)
				if (scan -> netmask.iabuf [3 - (j >> 3)]
				    & (1 << (j & 7)))
					break;
			strcpy (n1buf, piaddr (subnet -> net));
			error ("subnet %s/%d conflicts with subnet %s/%d",
			       n1buf, i, piaddr (scan -> net), j);
		}
	}

	/* XXX Sort the nets into a balanced tree to make searching quicker. */
	subnet -> next_subnet = subnets;
	subnets = subnet;
}
	
/* Enter a new shared network into the shared network list. */

void enter_shared_network (share)
	struct shared_network *share;
{
	/* XXX Sort the nets into a balanced tree to make searching quicker. */
	share -> next = shared_networks;
	shared_networks = share;
}
	
/* Enter a lease into the system.   This is called by the parser each
   time it reads in a new lease.   If the subnet for that lease has
   already been read in (usually the case), just update that lease;
   otherwise, allocate temporary storage for the lease and keep it around
   until we're done reading in the config file. */

void enter_lease (lease)
	struct lease *lease;
{
	struct lease *comp = find_lease_by_ip_addr (lease -> ip_addr);

	/* If we don't have a place for this lease yet, save it for
	   later. */
	if (!comp) {
		comp = new_lease ("enter_lease");
		if (!comp) {
			error ("No memory for lease %s\n",
			       piaddr (lease -> ip_addr));
		}
		*comp = *lease;
		lease -> next = dangling_leases;
		lease -> prev = (struct lease *)0;
		dangling_leases = lease;
	} else {
		/* Record the hostname information in the lease. */
		comp -> hostname = lease -> hostname;
		comp -> client_hostname = lease -> client_hostname;
		supersede_lease (comp, lease, 0);
	}
}

/* Replace the data in an existing lease with the data in a new lease;
   adjust hash tables to suit, and insertion sort the lease into the
   list of leases by expiry time so that we can always find the oldest
   lease. */

int supersede_lease (comp, lease, commit)
	struct lease *comp, *lease;
	int commit;
{
	int enter_uid = 0;
	int enter_hwaddr = 0;
	struct lease *lp;

	/* Static leases are not currently kept in the database... */
	if (lease -> flags & STATIC_LEASE)
		return 1;

	/* If the existing lease hasn't expired and has a different
	   unique identifier or, if it doesn't have a unique
	   identifier, a different hardware address, then the two
	   leases are in conflict.  If the existing lease has a uid
	   and the new one doesn't, but they both have the same
	   hardware address, and dynamic bootp is allowed on this
	   lease, then we allow that, in case a dynamic BOOTP lease is
	   requested *after* a DHCP lease has been assigned. */

	if (!(lease -> flags & ABANDONED_LEASE) &&
	    comp -> ends > cur_time &&
	    (((comp -> uid && lease -> uid) &&
	      (comp -> uid_len != lease -> uid_len ||
	       memcmp (comp -> uid, lease -> uid, comp -> uid_len))) ||
	     (!comp -> uid &&
	      ((comp -> hardware_addr.htype !=
		lease -> hardware_addr.htype) ||
	       (comp -> hardware_addr.hlen !=
		lease -> hardware_addr.hlen) ||
	       memcmp (comp -> hardware_addr.haddr,
		       lease -> hardware_addr.haddr,
		       comp -> hardware_addr.hlen))))) {
		warn ("Lease conflict at %s",
		      piaddr (comp -> ip_addr));
		return 0;
	} else {
		/* If there's a Unique ID, dissociate it from the hash
		   table and free it if necessary. */
		if (comp -> uid) {
			uid_hash_delete (comp);
			enter_uid = 1;
			if (comp -> uid != &comp -> uid_buf [0]) {
				free (comp -> uid);
				comp -> uid_max = 0;
				comp -> uid_len = 0;
			}
			comp -> uid = (unsigned char *)0;
		} else
			enter_uid = 1;

		if (comp -> hardware_addr.htype &&
		    ((comp -> hardware_addr.hlen !=
		      lease -> hardware_addr.hlen) ||
		     (comp -> hardware_addr.htype !=
		      lease -> hardware_addr.htype) ||
		     memcmp (comp -> hardware_addr.haddr,
			     lease -> hardware_addr.haddr,
			     comp -> hardware_addr.hlen))) {
			hw_hash_delete (comp);
			enter_hwaddr = 1;
		} else if (!comp -> hardware_addr.htype)
			enter_hwaddr = 1;

		/* Copy the data files, but not the linkages. */
		comp -> starts = lease -> starts;
		comp -> timestamp = lease -> timestamp;
		if (lease -> uid) {
			if (lease -> uid_len < sizeof (lease -> uid_buf)) {
				memcpy (comp -> uid_buf,
					lease -> uid, lease -> uid_len);
				comp -> uid = &comp -> uid_buf [0];
				comp -> uid_max = sizeof comp -> uid_buf;
			} else if (lease -> uid != &lease -> uid_buf [0]) {
				comp -> uid = lease -> uid;
				comp -> uid_max = lease -> uid_max;
				lease -> uid = (unsigned char *)0;
				lease -> uid_max = 0;
			} else {
				error ("corrupt lease uid."); /* XXX */
			}
		} else {
			comp -> uid = (unsigned char *)0;
			comp -> uid_max = 0;
		}
		comp -> uid_len = lease -> uid_len;
		comp -> host = lease -> host;
		comp -> hardware_addr = lease -> hardware_addr;
		comp -> flags = ((lease -> flags & ~PERSISTENT_FLAGS) |
				 (comp -> flags & ~EPHEMERAL_FLAGS));

		/* Record the lease in the uid hash if necessary. */
		if (enter_uid && lease -> uid) {
			uid_hash_add (comp);
		}

		/* Record it in the hardware address hash if necessary. */
		if (enter_hwaddr && lease -> hardware_addr.htype) {
			hw_hash_add (comp);
		}

		/* Remove the lease from its current place in the 
		   timeout sequence. */
		if (comp -> prev) {
			comp -> prev -> next = comp -> next;
		} else {
			comp -> shared_network -> leases = comp -> next;
		}
		if (comp -> next) {
			comp -> next -> prev = comp -> prev;
		}
		if (comp -> shared_network -> last_lease == comp) {
			comp -> shared_network -> last_lease = comp -> prev;
		}

		/* Find the last insertion point... */
		if (comp == comp -> shared_network -> insertion_point ||
		    !comp -> shared_network -> insertion_point) {
			lp = comp -> shared_network -> leases;
		} else {
			lp = comp -> shared_network -> insertion_point;
		}

		if (!lp) {
			/* Nothing on the list yet?    Just make comp the
			   head of the list. */
			comp -> shared_network -> leases = comp;
			comp -> shared_network -> last_lease = comp;
		} else if (lp -> ends > lease -> ends) {
			/* Skip down the list until we run out of list
			   or find a place for comp. */
			while (lp -> next && lp -> ends > lease -> ends) {
				lp = lp -> next;
			}
			if (lp -> ends > lease -> ends) {
				/* If we ran out of list, put comp
				   at the end. */
				lp -> next = comp;
				comp -> prev = lp;
				comp -> next = (struct lease *)0;
				comp -> shared_network -> last_lease = comp;
			} else {
				/* If we didn't, put it between lp and
				   the previous item on the list. */
				if ((comp -> prev = lp -> prev))
					comp -> prev -> next = comp;
				comp -> next = lp;
				lp -> prev = comp;
			}
		} else {
			/* Skip up the list until we run out of list
			   or find a place for comp. */
			while (lp -> prev && lp -> ends < lease -> ends) {
				lp = lp -> prev;
			}
			if (lp -> ends < lease -> ends) {
				/* If we ran out of list, put comp
				   at the beginning. */
				lp -> prev = comp;
				comp -> next = lp;
				comp -> prev = (struct lease *)0;
				comp -> shared_network -> leases = comp;
			} else {
				/* If we didn't, put it between lp and
				   the next item on the list. */
				if ((comp -> next = lp -> next))
					comp -> next -> prev = comp;
				comp -> prev = lp;
				lp -> next = comp;
			}
		}
		comp -> shared_network -> insertion_point = comp;
		comp -> ends = lease -> ends;
	}

	/* Return zero if we didn't commit the lease to permanent storage;
	   nonzero if we did. */
	return commit && write_lease (comp) && commit_leases ();
}

/* Release the specified lease and re-hash it as appropriate. */

void release_lease (lease)
	struct lease *lease;
{
	struct lease lt;

	lt = *lease;
	lt.ends = cur_time;
	supersede_lease (lease, &lt, 1);
	note ("Released lease for IP address %s",
	      piaddr (lease -> ip_addr));
}

/* Abandon the specified lease for the specified time. sets it's 
   particulars to zero, the end time apropriately and re-hash it as
   appropriate. abandons permanently if abtime is 0 */

void abandon_lease (lease, message)
	struct lease *lease;
	char *message;
{
	struct lease lt;
	TIME abtime;

	abtime = lease -> subnet -> group -> default_lease_time;
	lease -> flags |= ABANDONED_LEASE;
	lt = *lease;
	lt.ends = cur_time + abtime;
	warn ("Abandoning IP address %s for %d seconds: %s",
	      piaddr (lease -> ip_addr), abtime, message);
	lt.hardware_addr.htype = 0;
	lt.hardware_addr.hlen = 0;
	lt.uid = (unsigned char *)0;
	lt.uid_len = 0;
	supersede_lease (lease, &lt, 1);
}

/* Locate the lease associated with a given IP address... */

struct lease *find_lease_by_ip_addr (addr)
	struct iaddr addr;
{
	struct lease *lease = (struct lease *)hash_lookup (lease_ip_addr_hash,
							   addr.iabuf,
							   addr.len);
	return lease;
}

struct lease *find_lease_by_uid (uid, len)
	unsigned char *uid;
	int len;
{
	struct lease *lease = (struct lease *)hash_lookup (lease_uid_hash,
							   uid, len);
	return lease;
}

struct lease *find_lease_by_hw_addr (hwaddr, hwlen)
	unsigned char *hwaddr;
	int hwlen;
{
	struct lease *lease = (struct lease *)hash_lookup (lease_hw_addr_hash,
							   hwaddr, hwlen);
	return lease;
}

/* Add the specified lease to the uid hash. */

void uid_hash_add (lease)
	struct lease *lease;
{
	struct lease *head =
		find_lease_by_uid (lease -> uid, lease -> uid_len);
	struct lease *scan;

#ifdef DEBUG
	if (lease -> n_uid)
		abort ();
#endif

	/* If it's not in the hash, just add it. */
	if (!head)
		add_hash (lease_uid_hash, lease -> uid,
			  lease -> uid_len, (unsigned char *)lease);
	else {
		/* Otherwise, attach it to the end of the list. */
		for (scan = head; scan -> n_uid; scan = scan -> n_uid)
#ifdef DEBUG
			if (scan == lease)
				abort ()
#endif
					;
		scan -> n_uid = lease;
	}
}

/* Delete the specified lease from the uid hash. */

void uid_hash_delete (lease)
	struct lease *lease;
{
	struct lease *head =
		find_lease_by_uid (lease -> uid, lease -> uid_len);
	struct lease *scan;

	/* If it's not in the hash, we have no work to do. */
	if (!head) {
		lease -> n_uid = (struct lease *)0;
		return;
	}

	/* If the lease we're freeing is at the head of the list,
	   remove the hash table entry and add a new one with the
	   next lease on the list (if there is one). */
	if (head == lease) {
		delete_hash_entry (lease_uid_hash,
				   lease -> uid, lease -> uid_len);
		if (lease -> n_uid)
			add_hash (lease_uid_hash,
				  lease -> n_uid -> uid,
				  lease -> n_uid -> uid_len,
				  (unsigned char *)(lease -> n_uid));
	} else {
		/* Otherwise, look for the lease in the list of leases
		   attached to the hash table entry, and remove it if
		   we find it. */
		for (scan = head; scan -> n_uid; scan = scan -> n_uid) {
			if (scan -> n_uid == lease) {
				scan -> n_uid = scan -> n_uid -> n_uid;
				break;
			}
		}
	}
	lease -> n_uid = (struct lease *)0;
}

/* Add the specified lease to the hardware address hash. */

void hw_hash_add (lease)
	struct lease *lease;
{
	struct lease *head =
		find_lease_by_hw_addr (lease -> hardware_addr.haddr,
				       lease -> hardware_addr.hlen);
	struct lease *scan;

	/* If it's not in the hash, just add it. */
	if (!head)
		add_hash (lease_hw_addr_hash,
			  lease -> hardware_addr.haddr,
			  lease -> hardware_addr.hlen,
			  (unsigned char *)lease);
	else {
		/* Otherwise, attach it to the end of the list. */
		for (scan = head; scan -> n_hw; scan = scan -> n_hw)
			;
		scan -> n_hw = lease;
	}
}

/* Delete the specified lease from the hardware address hash. */

void hw_hash_delete (lease)
	struct lease *lease;
{
	struct lease *head =
		find_lease_by_hw_addr (lease -> hardware_addr.haddr,
				       lease -> hardware_addr.hlen);
	struct lease *scan;

	/* If it's not in the hash, we have no work to do. */
	if (!head) {
		lease -> n_hw = (struct lease *)0;
		return;
	}

	/* If the lease we're freeing is at the head of the list,
	   remove the hash table entry and add a new one with the
	   next lease on the list (if there is one). */
	if (head == lease) {
		delete_hash_entry (lease_hw_addr_hash,
				   lease -> hardware_addr.haddr,
				   lease -> hardware_addr.hlen);
		if (lease -> n_hw)
			add_hash (lease_hw_addr_hash,
				  lease -> n_hw -> hardware_addr.haddr,
				  lease -> n_hw -> hardware_addr.hlen,
				  (unsigned char *)(lease -> n_hw));
	} else {
		/* Otherwise, look for the lease in the list of leases
		   attached to the hash table entry, and remove it if
		   we find it. */
		for (scan = head; scan -> n_hw; scan = scan -> n_hw) {
			if (scan -> n_hw == lease) {
				scan -> n_hw = scan -> n_hw -> n_hw;
				break;
			}
		}
	}
	lease -> n_hw = (struct lease *)0;
}


struct class *add_class (type, name)
	int type;
	char *name;
{
	struct class *class = new_class ("add_class");
	char *tname = (char *)malloc (strlen (name) + 1);

	if (!vendor_class_hash)
		vendor_class_hash = new_hash ();
	if (!user_class_hash)
		user_class_hash = new_hash ();

	if (!tname || !class || !vendor_class_hash || !user_class_hash)
		return (struct class *)0;

	memset (class, 0, sizeof *class);
	strcpy (tname, name);
	class -> name = tname;

	if (type)
		add_hash (user_class_hash,
			  tname, strlen (tname), (unsigned char *)class);
	else
		add_hash (vendor_class_hash,
			  tname, strlen (tname), (unsigned char *)class);
	return class;
}

struct class *find_class (type, name, len)
	int type;
	char *name;
	int len;
{
	struct class *class =
		(struct class *)hash_lookup (type
					     ? user_class_hash
					     : vendor_class_hash, name, len);
	return class;
}	

struct group *clone_group (group, caller)
	struct group *group;
	char *caller;
{
	struct group *g = new_group (caller);
	if (!g)
		error ("%s: can't allocate new group", caller);
	*g = *group;
	return g;
}

/* Write all interesting leases to permanent storage. */

void write_leases ()
{
	struct lease *l;
	struct shared_network *s;

	for (s = shared_networks; s; s = s -> next) {
		for (l = s -> leases; l; l = l -> next) {
			if (l -> hardware_addr.hlen ||
			    l -> uid_len ||
			    (l -> flags & ABANDONED_LEASE))
				if (!write_lease (l))
					error ("Can't rewrite lease database");
		}
	}
	if (!commit_leases ())
		error ("Can't commit leases to new database: %m");
}

void dump_subnets ()
{
	struct lease *l;
	struct shared_network *s;
	struct subnet *n;

	for (s = shared_networks; s; s = s -> next) {
		for (n = subnets; n; n = n -> next_sibling) {
			debug ("Subnet %s", piaddr (n -> net));
			debug ("   netmask %s",
			       piaddr (n -> netmask));
		}
		for (l = s -> leases; l; l = l -> next) {
			print_lease (l);
		}
		debug ("Last Lease:");
		print_lease (s -> last_lease);
	}
}