isc-dhcp/common/discover.c

/* dispatch.c

   Network input dispatcher... */

/*
 * Copyright (c) 1995, 1996, 1998 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: discover.c,v 1.2 1998/11/11 07:50:51 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium.  All rights reserved.\n";
#endif /* not lint */

#include "dhcpd.h"
#include <sys/ioctl.h>

struct interface_info *interfaces, *dummy_interfaces;
extern int interfaces_invalidated;
int quiet_interface_discovery;

void (*bootp_packet_handler) PROTO ((struct interface_info *,
				     struct dhcp_packet *, int, unsigned int,
				     struct iaddr, struct hardware *));

static void got_one PROTO ((struct protocol *));

/* Use the SIOCGIFCONF ioctl to get a list of all the attached interfaces.
   For each interface that's of type INET and not the loopback interface,
   register that interface with the network I/O software, figure out what
   subnet it's on, and add it to the list of interfaces. */

void discover_interfaces (state)
	int state;
{
	struct interface_info *tmp;
	struct interface_info *last, *next;
	char buf [8192];
	struct ifconf ic;
	struct ifreq ifr;
	int i;
	int sock;
	int address_count = 0;
	struct subnet *subnet;
	struct shared_network *share;
	struct sockaddr_in foo;
	int ir;
#ifdef ALIAS_NAMES_PERMUTED
	char *s;
#endif
#ifdef USE_FALLBACK
	static struct shared_network fallback_network;
#endif

	/* Create an unbound datagram socket to do the SIOCGIFADDR ioctl on. */
	if ((sock = socket (AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
		error ("Can't create addrlist socket");

	/* Get the interface configuration information... */
	ic.ifc_len = sizeof buf;
	ic.ifc_ifcu.ifcu_buf = (caddr_t)buf;
	i = ioctl(sock, SIOCGIFCONF, &ic);

	if (i < 0)
		error ("ioctl: SIOCGIFCONF: %m");

	/* If we already have a list of interfaces, and we're running as
	   a DHCP server, the interfaces were requested. */
	if (interfaces && (state == DISCOVER_SERVER ||
			   state == DISCOVER_RELAY ||
			   state == DISCOVER_REQUESTED))
		ir = 0;
	else if (state == DISCOVER_UNCONFIGURED)
		ir = INTERFACE_REQUESTED | INTERFACE_AUTOMATIC;
	else
		ir = INTERFACE_REQUESTED;

	/* Cycle through the list of interfaces looking for IP addresses.
	   Go through twice; once to count the number of addresses, and a
	   second time to copy them into an array of addresses. */
	for (i = 0; i < ic.ifc_len;) {
		struct ifreq *ifp = (struct ifreq *)((caddr_t)ic.ifc_req + i);
#ifdef HAVE_SA_LEN
		if (ifp -> ifr_addr.sa_len)
			i += (sizeof ifp -> ifr_name) + ifp -> ifr_addr.sa_len;
		else
#endif
			i += sizeof *ifp;

#ifdef ALIAS_NAMES_PERMUTED
		if ((s = strrchr (ifp -> ifr_name, ':'))) {
			*s = 0;
		}
#endif

#ifdef SKIP_DUMMY_INTERFACES
		if (!strncmp (ifp -> ifr_name, "dummy", 5))
			continue;
#endif


		/* See if this is the sort of interface we want to
		   deal with. */
		strcpy (ifr.ifr_name, ifp -> ifr_name);
		if (ioctl (sock, SIOCGIFFLAGS, &ifr) < 0)
			error ("Can't get interface flags for %s: %m",
			       ifr.ifr_name);

		/* See if we've seen an interface that matches this one. */
		for (tmp = interfaces; tmp; tmp = tmp -> next)
			if (!strcmp (tmp -> name, ifp -> ifr_name))
				break;

		/* Skip loopback, point-to-point and down interfaces,
		   except don't skip down interfaces if we're trying to
		   get a list of configurable interfaces. */
		if ((((ifr.ifr_flags & IFF_LOOPBACK) ||
#ifdef IFF_POINTOPOINT
		      (ifr.ifr_flags & IFF_POINTOPOINT))
		     && !tmp) ||
#endif
		    (!(ifr.ifr_flags & IFF_UP) &&
		     state != DISCOVER_UNCONFIGURED))
			continue;
		
		/* If there isn't already an interface by this name,
		   allocate one. */
		if (!tmp) {
			tmp = ((struct interface_info *)
			       dmalloc (sizeof *tmp, "discover_interfaces"));
			if (!tmp)
				error ("Insufficient memory to %s %s",
				       "record interface", ifp -> ifr_name);
			strcpy (tmp -> name, ifp -> ifr_name);
			tmp -> circuit_id = (u_int8_t *)tmp -> name;
			tmp -> circuit_id_len = strlen (tmp -> name);
			tmp -> remote_id = 0;
			tmp -> remote_id_len = 0;
			tmp -> next = interfaces;
			tmp -> flags = ir;
			interfaces = tmp;
		}

		/* If we have the capability, extract link information
		   and record it in a linked list. */
#ifdef AF_LINK
		if (ifp -> ifr_addr.sa_family == AF_LINK) {
			struct sockaddr_dl *foo = ((struct sockaddr_dl *)
						   (&ifp -> ifr_addr));
#if defined (HAVE_SIN_LEN)
			tmp -> hw_address.hlen = foo -> sdl_alen;
#else
			tmp -> hw_address.hlen = 6; /* XXX!!! */
#endif
			tmp -> hw_address.htype = HTYPE_ETHER; /* XXX */
			memcpy (tmp -> hw_address.haddr,
				LLADDR (foo), tmp -> hw_address.hlen);
		} else
#endif /* AF_LINK */

		if (ifp -> ifr_addr.sa_family == AF_INET) {
			struct iaddr addr;

#if defined (SIOCGIFHWADDR) && !defined (AF_LINK)
			struct ifreq ifr;
			struct sockaddr sa;
			int b, sk;
			
			/* Read the hardware address from this interface. */
			ifr = *ifp;
			if (ioctl (sock, SIOCGIFHWADDR, &ifr) < 0)
				error ("Can't get hardware address for %s: %m",
				       ifr.ifr_name);

			sa = *(struct sockaddr *)&ifr.ifr_hwaddr;
					
			switch (sa.sa_family) {
#ifdef ARPHRD_LOOPBACK
			      case ARPHRD_LOOPBACK:
				/* ignore loopback interface */
				break;
#endif

			      case ARPHRD_ETHER:
				tmp -> hw_address.hlen = 6;
				tmp -> hw_address.htype = ARPHRD_ETHER;
				memcpy (tmp -> hw_address.haddr,
					sa.sa_data, 6);
				break;

#ifndef ARPHRD_IEEE802
# define ARPHRD_IEEE802 HTYPE_IEEE802
#endif
			      case ARPHRD_IEEE802:
				tmp -> hw_address.hlen = 6;
				tmp -> hw_address.htype = ARPHRD_IEEE802;
				memcpy (tmp -> hw_address.haddr,
					sa.sa_data, 6);
				break;

#ifdef ARPHRD_FDDI
			      case ARPHRD_FDDI:
				tmp -> hw_address.hlen = 16;
				tmp -> hw_address.htype = ARPHRD_FDDI;
				memcpy (tmp -> hw_address.haddr,
					sa.sa_data, 16);

				break;
#endif

#ifdef ARPHRD_METRICOM
			      case ARPHRD_METRICOM:
				tmp -> hw_address.hlen = 6;
				tmp -> hw_address.htype = ARPHRD_METRICOM;
				memcpy (tmp -> hw_address.haddr,
					sa.sa_data, 6);

				break;
#endif

			      default:
				error ("%s: unknown hardware address type %d",
				       ifr.ifr_name, sa.sa_family);
			}
#endif /* defined (SIOCGIFHWADDR) && !defined (AF_LINK) */

			/* Get a pointer to the address... */
			memcpy (&foo, &ifp -> ifr_addr,
				sizeof ifp -> ifr_addr);

			/* We don't want the loopback interface. */
			if (foo.sin_addr.s_addr == htonl (INADDR_LOOPBACK))
				continue;


			/* If this is the first real IP address we've
			   found, keep a pointer to ifreq structure in
			   which we found it. */
			if (!tmp -> ifp) {
				struct ifreq *tif;
#ifdef HAVE_SA_LEN
				int len = ((sizeof ifp -> ifr_name) +
					   ifp -> ifr_addr.sa_len);
#else
				int len = sizeof *ifp;
#endif
				tif = (struct ifreq *)malloc (len);
				if (!tif)
					error ("no space to remember ifp.");
				memcpy (tif, ifp, len);
				tmp -> ifp = tif;
				tmp -> primary_address = foo.sin_addr;
			}

			/* Grab the address... */
			addr.len = 4;
			memcpy (addr.iabuf, &foo.sin_addr.s_addr,
				addr.len);

			/* If there's a registered subnet for this address,
			   connect it together... */
			if ((subnet = find_subnet (addr))) {
				/* If this interface has multiple aliases
				   on the same subnet, ignore all but the
				   first we encounter. */
				if (!subnet -> interface) {
					subnet -> interface = tmp;
					subnet -> interface_address = addr;
				} else if (subnet -> interface != tmp) {
					warn ("Multiple %s %s: %s %s", 
					      "interfaces match the",
					      "same subnet",
					      subnet -> interface -> name,
					      tmp -> name);
				}
				share = subnet -> shared_network;
				if (tmp -> shared_network &&
				    tmp -> shared_network != share) {
					warn ("Interface %s matches %s",
					      tmp -> name,
					      "multiple shared networks");
				} else {
					tmp -> shared_network = share;
				}

				if (!share -> interface) {
					share -> interface = tmp;
				} else if (share -> interface != tmp) {
					warn ("Multiple %s %s: %s %s", 
					      "interfaces match the",
					      "same shared network",
					      share -> interface -> name,
					      tmp -> name);
				}
			}
		}
	}

	/* If we're just trying to get a list of interfaces that we might
	   be able to configure, we can quit now. */
	if (state == DISCOVER_UNCONFIGURED)
		return;

	/* Weed out the interfaces that did not have IP addresses. */
	last = (struct interface_info *)0;
	for (tmp = interfaces; tmp; tmp = next) {
		next = tmp -> next;
		if ((tmp -> flags & INTERFACE_AUTOMATIC) &&
		    state == DISCOVER_REQUESTED)
			tmp -> flags &= ~(INTERFACE_AUTOMATIC |
					  INTERFACE_REQUESTED);
		if (!tmp -> ifp || !(tmp -> flags & INTERFACE_REQUESTED)) {
			if ((tmp -> flags & INTERFACE_REQUESTED) != ir)
				error ("%s: not found", tmp -> name);
			if (!last)
				interfaces = interfaces -> next;
			else
				last -> next = tmp -> next;

			/* Remember the interface in case we need to know
			   about it later. */
			tmp -> next = dummy_interfaces;
			dummy_interfaces = tmp;
			continue;
		}
		last = tmp;

		memcpy (&foo, &tmp -> ifp -> ifr_addr,
			sizeof tmp -> ifp -> ifr_addr);

		/* We must have a subnet declaration for each interface. */
		if (!tmp -> shared_network && (state == DISCOVER_SERVER))
			error ("No subnet declaration for %s (%s).",
			       tmp -> name, inet_ntoa (foo.sin_addr));

		/* Find subnets that don't have valid interface
		   addresses... */
		for (subnet = (tmp -> shared_network
			       ? tmp -> shared_network -> subnets
			       : (struct subnet *)0);
		     subnet; subnet = subnet -> next_sibling) {
			if (!subnet -> interface_address.len) {
				/* Set the interface address for this subnet
				   to the first address we found. */
				subnet -> interface_address.len = 4;
				memcpy (subnet -> interface_address.iabuf,
					&foo.sin_addr.s_addr, 4);
			}
		}

		/* Register the interface... */
		if_register_receive (tmp);
		if_register_send (tmp);
	}

	/* Now register all the remaining interfaces as protocols. */
	for (tmp = interfaces; tmp; tmp = tmp -> next)
		add_protocol (tmp -> name, tmp -> rfdesc, got_one, tmp);

	close (sock);

#ifdef USE_FALLBACK
	strcpy (fallback_interface.name, "fallback");	
	fallback_interface.shared_network = &fallback_network;
	fallback_network.name = "fallback-net";
	if_register_fallback (&fallback_interface);
	add_protocol ("fallback", fallback_interface.wfdesc,
		      fallback_discard, &fallback_interface);
#endif
}

void reinitialize_interfaces ()
{
	struct interface_info *ip;

	for (ip = interfaces; ip; ip = ip -> next) {
		if_reinitialize_receive (ip);
		if_reinitialize_send (ip);
	}

#ifdef USE_FALLBACK
	if_reinitialize_fallback (&fallback_interface);
#endif

	interfaces_invalidated = 1;
}
static void got_one (l)
	struct protocol *l;
{
	struct sockaddr_in from;
	struct hardware hfrom;
	struct iaddr ifrom;
	int result;
	union {
		unsigned char packbuf [4095]; /* Packet input buffer.
					 	 Must be as large as largest
						 possible MTU. */
		struct dhcp_packet packet;
	} u;
	struct interface_info *ip = l -> local;

	if ((result =
	     receive_packet (ip, u.packbuf, sizeof u, &from, &hfrom)) < 0) {
		warn ("receive_packet failed on %s: %m", ip -> name);
		return;
	}
	if (result == 0)
		return;

	if (bootp_packet_handler) {
		ifrom.len = 4;
		memcpy (ifrom.iabuf, &from.sin_addr, ifrom.len);

		(*bootp_packet_handler) (ip, &u.packet, result,
					 from.sin_port, ifrom, &hfrom);
	}
}