isc-dhcp/common/discover.c

/* dispatch.c

   Network input dispatcher... */

/*
 * Copyright (c) 1996-1999 Internet Software Consortium.
 * Use is subject to license terms which appear in the file named
 * ISC-LICENSE that should have accompanied this file when you
 * received it.   If a file named ISC-LICENSE did not accompany this
 * file, or you are not sure the one you have is correct, you may
 * obtain an applicable copy of the license at:
 *
 *             http://www.isc.org/isc-license-1.0.html. 
 *
 * This file is part of the ISC DHCP distribution.   The documentation
 * associated with this file is listed in the file DOCUMENTATION,
 * included in the top-level directory of this release.
 *
 * Support and other services are available for ISC products - see
 * http://www.isc.org for more information.
 */

#ifndef lint
static char copyright[] =
"$Id: discover.c,v 1.10 1999/07/13 12:58:03 mellon Exp $ Copyright (c) 1995, 1996, 1998, 1999 The Internet Software Consortium.  All rights reserved.\n";
#endif /* not lint */

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

struct interface_info *interfaces, *dummy_interfaces, *fallback_interface;
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 *));

/* 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;
	struct ifreq *tif;
#ifdef ALIAS_NAMES_PERMUTED
	char *s;
#endif

	/* Create an unbound datagram socket to do the SIOCGIFADDR ioctl on. */
	if ((sock = socket (AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
		log_fatal ("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)
		log_fatal ("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. */
	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 > sizeof (struct sockaddr))
			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)
			log_fatal ("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 ||
		      ifr.ifr_flags & IFF_POINTOPOINT) && !tmp) ||
		    (!(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)
				log_fatal ("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 HAVE_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;

			/* 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) {
#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)
					log_fatal ("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) {
					log_error ("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) {
					log_error ("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) {
					log_error ("Multiple %s %s: %s %s", 
					      "interfaces match the",
					      "same shared network",
					      share -> interface -> name,
					      tmp -> name);
				}
			}
		}
	}

#if defined (LINUX_SLASHPROC_DISCOVERY)
	/* On Linux, interfaces that don't have IP addresses don't show up
	   in the SIOCGIFCONF syscall.   We got away with this prior to
	   Linux 2.1 because we would give each interface an IP address of
	   0.0.0.0 before trying to boot, but that doesn't work after 2.1
	   because we're using LPF, because we can't configure interfaces
	   with IP addresses of 0.0.0.0 anymore (grumble).   This only
	   matters for the DHCP client, of course - the relay agent and
	   server should only care about interfaces that are configured
	   with IP addresses anyway.

	   The PROCDEV_DEVICE (/proc/net/dev) is a kernel-supplied file
	   that, when read, prints a human readable network status.   We
	   extract the names of the network devices by skipping the first
	   two lines (which are header) and then parsing off everything
	   up to the colon in each subsequent line - these lines start
	   with the interface name, then a colon, then a bunch of
	   statistics.   Yes, Virgina, this is a kludge, but you work
	   with what you have. */

	if (state == DISCOVER_UNCONFIGURED) {
		FILE *proc_dev;
		char buffer [256];
		int skip = 2;

		proc_dev = fopen (PROCDEV_DEVICE, "r");
		if (!proc_dev)
			log_fatal ("%s: %m", PROCDEV_DEVICE);

		while (fgets (buffer, sizeof buffer, proc_dev)) {
			char *name = buffer;
			char *sep;

			/* Skip the first two blocks, which are header
			   lines. */
			if (skip) {
				--skip;
				continue;
			}

			sep = strrchr (buffer, ':');
			if (sep)
				*sep = '\0';
			while (*name == ' ')
				name++;

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

			/* If we found one, nothing more to do.. */
			if (tmp)
				continue;

			/* Otherwise, allocate one. */
			tmp = ((struct interface_info *)
			       dmalloc (sizeof *tmp, "discover_interfaces"));
			if (!tmp)
				log_fatal ("Insufficient memory to %s %s",
				       "record interface", name);
			memset (tmp, 0, sizeof *tmp);
			strcpy (tmp -> name, name);

			tmp -> flags = ir;
			tmp -> next = interfaces;
			interfaces = tmp;
		}
		fclose (proc_dev);
	}
#endif

	/* Now cycle through all the interfaces we found, looking for
	   hardware addresses. */
#if defined (HAVE_SIOCGIFHWADDR) && !defined (HAVE_AF_LINK)
	for (tmp = interfaces; tmp; tmp = tmp -> next) {
		struct ifreq ifr;
		struct sockaddr sa;
		int b, sk;
		
		if (!tmp -> ifp) {
			/* Make up an ifreq structure. */
			tif = (struct ifreq *)malloc (sizeof (struct ifreq));
			if (!tif)
				log_fatal ("no space to remember ifp.");
			memset (tif, 0, sizeof (struct ifreq));
			strcpy (tif -> ifr_name, tmp -> name);
			tmp -> ifp = tif;
		}

		/* Read the hardware address from this interface. */
		ifr = *tmp -> ifp;
		if (ioctl (sock, SIOCGIFHWADDR, &ifr) < 0)
			continue;
		
		sa = *(struct sockaddr *)&ifr.ifr_hwaddr;
		
		switch (sa.sa_family) {
#ifdef HAVE_ARPHRD_TUNNEL
		      case ARPHRD_TUNNEL:
			/* ignore tunnel interfaces. */
#endif
#ifdef HAVE_ARPHRD_ROSE
		      case ARPHRD_ROSE:
#endif
#ifdef HAVE_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 HAVE_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;

#ifndef HAVE_ARPHRD_FDDI
# define ARPHRD_FDDI HTYPE_FDDI
#endif
		      case ARPHRD_FDDI:
			tmp -> hw_address.hlen = 16;
			tmp -> hw_address.htype = HTYPE_FDDI; /* XXX */
			memcpy (tmp -> hw_address.haddr, sa.sa_data, 16);
			break;

#ifdef HAVE_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

#ifdef HAVE_ARPHRD_AX25
		      case ARPHRD_AX25:
			tmp -> hw_address.hlen = 6;
			tmp -> hw_address.htype = ARPHRD_AX25;
			memcpy (tmp -> hw_address.haddr, sa.sa_data, 6);
			break;
#endif

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

		      default:
			log_error ("%s: unknown hardware address type %d",
				   ifr.ifr_name, sa.sa_family);
			break;
		}
	}
#endif /* defined (HAVE_SIOCGIFHWADDR) && !defined (HAVE_AF_LINK) */

	/* 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)
				log_fatal ("%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)) {
			log_error ("No subnet declaration for %s (%s).",
				   tmp -> name, inet_ntoa (foo.sin_addr));
			log_error ("Please write a subnet declaration in %s",
				   "your dhcpd.conf file for the");
			log_fatal ("network segment to which interface %s %s",
				   tmp -> name, "is attached.");
		}

		/* 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);

	maybe_setup_fallback ();
}

struct interface_info *setup_fallback ()
{
	fallback_interface =
		((struct interface_info *)
		 dmalloc (sizeof *fallback_interface, "discover_interfaces"));
	if (!fallback_interface)
		log_fatal ("Insufficient memory to record fallback interface.");
	memset (fallback_interface, 0, sizeof *fallback_interface);
	strcpy (fallback_interface -> name, "fallback");
	fallback_interface -> shared_network =
		new_shared_network ("parse_statement");
	if (!fallback_interface -> shared_network)
		log_fatal ("No memory for shared subnet");
	memset (fallback_interface -> shared_network, 0,
		sizeof (struct shared_network));
	fallback_interface -> shared_network -> name = "fallback-net";
	return fallback_interface;
}

void reinitialize_interfaces ()
{
	struct interface_info *ip;

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

	if (fallback_interface)
		if_reinitialize_send (fallback_interface);

	interfaces_invalidated = 1;
}

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) {
		log_error ("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);
	}
}