path: root/usr.sbin/dhcp/common/dispatch.c

/* dispatch.c

   Network input dispatcher... */

/*
 * Copyright (c) 1995, 1996, 1997, 1998, 1999
 * 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''.
 */

#include "dhcpd.h"
#include <ifaddrs.h>
#include <sys/ioctl.h>
#include <poll.h>
#include <net/if_media.h>


/* Most boxes has less than 16 interfaces, so this might be a good guess.  */
#define INITIAL_IFREQ_COUNT 16

struct interface_info *interfaces, *dummy_interfaces, *fallback_interface;
struct protocol *protocols;
struct timeout *timeouts;
static struct timeout *free_timeouts;
static int interfaces_invalidated;
void (*bootp_packet_handler) PROTO ((struct interface_info *,
				     struct dhcp_packet *, int, unsigned int,
				     struct iaddr, struct hardware *));

static int interface_status(struct interface_info *ifinfo);

int quiet_interface_discovery;

/* 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;
	int sock;
	struct subnet *subnet;
	struct shared_network *share;
	struct sockaddr_in foo;
	int ir;
	struct ifreq *tif;
	struct ifaddrs *ifap, *ifa;
#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)
		error ("Can't create addrlist socket");

	if (getifaddrs(&ifap) != 0)
		error ("getifaddrs failed");

	/* 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 (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
		/* See if this is the sort of interface we want to
		   deal with.  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 ((ifa->ifa_flags & IFF_LOOPBACK) ||
		    (ifa->ifa_flags & IFF_POINTOPOINT) ||
		    (!(ifa->ifa_flags & IFF_UP) &&
		     state != DISCOVER_UNCONFIGURED))
			continue;
		
		/* See if we've seen an interface that matches this one. */
		for (tmp = interfaces; tmp; tmp = tmp -> next)
			if (!strcmp (tmp -> name, ifa -> ifa_name))
				break;

		/* 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", ifa -> ifa_name);
			strlcpy (tmp -> name, ifa -> ifa_name, sizeof(tmp->name));
			tmp -> next = interfaces;
			tmp -> flags = ir;
			tmp -> noifmedia = tmp -> dead = tmp->errors = 0;
			interfaces = tmp;
		}

		/* If we have the capability, extract link information
		   and record it in a linked list. */
		if (ifa -> ifa_addr->sa_family == AF_LINK) {
			struct sockaddr_dl *foo = ((struct sockaddr_dl *)
						   (ifa -> ifa_addr));
			tmp -> hw_address.hlen = foo -> sdl_alen;
			tmp -> hw_address.htype = HTYPE_ETHER; /* XXX */
			memcpy (tmp -> hw_address.haddr,
				LLADDR (foo), foo -> sdl_alen);
		} else if (ifa -> ifa_addr->sa_family == AF_INET) {
			struct iaddr addr;

			/* Get a pointer to the address... */
			bcopy(ifa->ifa_addr, &foo, sizeof(foo));

			/* 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) {
				int len = (IFNAMSIZ +
					   ifa -> ifa_addr->sa_len);
				tif = (struct ifreq *)malloc (len);
				if (!tif)
					error ("no space to remember ifp.");
				strlcpy(tif->ifr_name, ifa->ifa_name, IFNAMSIZ);
				memcpy(&tif->ifr_addr, ifa->ifa_addr,
				    ifa->ifa_addr->sa_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);
				}
			}
		}
	}

	/* Now cycle through all the interfaces we found, looking for
	   hardware addresses. */

	/* 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)) {
			warn ("No subnet declaration for %s (%s).",
			      tmp -> name, inet_ntoa (foo.sin_addr));
			warn ("Please write a subnet declaration in your %s",
			      "dhcpd.conf file for the");
			error ("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);
	freeifaddrs(ifap);

	maybe_setup_fallback ();
}

struct interface_info *setup_fallback ()
{
	fallback_interface =
		((struct interface_info *)
		 dmalloc (sizeof *fallback_interface, "discover_interfaces"));
	if (!fallback_interface)
		error ("Insufficient memory to record fallback interface.");
	memset (fallback_interface, 0, sizeof *fallback_interface);
	strlcpy (fallback_interface -> name, "fallback", IFNAMSIZ);
	fallback_interface -> shared_network =
		new_shared_network ("parse_statement");
	if (!fallback_interface -> shared_network)
		error ("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;
}

/* Wait for packets to come in using poll().  When a packet comes in,
   call receive_packet to receive the packet and possibly strip hardware
   addressing information from it, and then call through the
   bootp_packet_handler hook to try to do something with it. */

void dispatch ()
{
	struct protocol *l;
	int nfds = 0;
	struct pollfd *fds;
	int count;
	int i;
	time_t howlong;
	int to_msec;

	nfds = 0;
	for (l = protocols; l; l = l -> next) {
		++nfds;
	}
	fds = (struct pollfd *)malloc ((nfds) * sizeof (struct pollfd));
	if (fds == NULL)
		error ("Can't allocate poll structures.");

	do {
		/* Call any expired timeouts, and then if there's
		   still a timeout registered, time out the select
		   call then. */
	      another:
		if (timeouts) {
			struct timeout *t;
			if (timeouts -> when <= cur_time) {
				t = timeouts;
				timeouts = timeouts -> next;
				(*(t -> func)) (t -> what);
				t -> next = free_timeouts;
				free_timeouts = t;
				goto another;
			}
			/*
			 * Figure timeout in milliseconds, and check for
			 * potential overflow, so we can cram into an int
			 * for poll, while not polling with a negative 
			 * timeout and blocking indefinetely.
			 */

			howlong = timeouts -> when - cur_time;
			if (howlong > INT_MAX / 1000)
				howlong = INT_MAX / 1000;
			to_msec = howlong * 1000;
		} else
			to_msec = -1;

		/* Set up the descriptors to be polled. */
		i = 0;
		
		for (l = protocols; l; l = l -> next) {
			struct interface_info *ip = l -> local;
			if (ip && (l->handler != got_one || !ip->dead)) {
				fds [i].fd = l -> fd;
				fds [i].events = POLLIN;
				fds [i].revents = 0;
				++i;
			}
		}

		if (i == 0) 
			error("No live interfaces to poll on - exiting.");
		
		/* Wait for a packet or a timeout... XXX */
		count = poll (fds, nfds, to_msec);

		/* Not likely to be transitory... */
		if (count == -1) {
			if (errno == EAGAIN || errno == EINTR) {
				GET_TIME (&cur_time);
				continue;
			}
			else
				error ("poll: %m");
		}

		/* Get the current time... */
		GET_TIME (&cur_time);

		i = 0;
		for (l = protocols; l; l = l -> next) {
		        struct interface_info *ip;
			ip = l->local;
			if ((fds [i].revents & POLLIN)) {
				fds [i].revents = 0;
				if (ip && (l->handler != got_one ||
				     !ip->dead))
					(*(l -> handler)) (l);
				if (interfaces_invalidated)
					break;
			}
			++i;
		}
		interfaces_invalidated = 0;
	} while (1);
}


void got_one (l)
	struct protocol *l;
{
	struct sockaddr_in from;
	struct hardware hfrom;
	struct iaddr ifrom;
	size_t 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)) == -1) {
		warn ("receive_packet failed on %s: %s", ip -> name, 
		      strerror(errno));
		ip->errors++;
		if ((! interface_status(ip)) 
		    || (ip->noifmedia && ip->errors > 20)) {
			/* our interface has gone away. */
			warn("Interface %s appears to no longer be valid",
			     ip->name); 
			ip->dead = 1;
			interfaces_invalidated = 1;
		}
		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);
	}
}

int
interface_status(struct interface_info *ifinfo)
{
	char * ifname = ifinfo->name;
	int ifsock = ifinfo->rfdesc;
	struct ifreq ifr;
	struct ifmediareq ifmr;
	
	/* get interface flags */
	memset(&ifr, 0, sizeof(ifr));
	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
	if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) < 0) {
		syslog(LOG_ERR, "ioctl(SIOCGIFFLAGS) on %s: %m",
		       ifname);
		goto inactive;
	}
	/*
	 * if one of UP and RUNNING flags is dropped,
	 * the interface is not active.
	 */
	if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING)) {
		goto inactive;
	}
	/* Next, check carrier on the interface, if possible */
	if (ifinfo->noifmedia) 
		goto active;
	memset(&ifmr, 0, sizeof(ifmr));
	strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
	if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) < 0) {
		if (errno != EINVAL) {
			syslog(LOG_DEBUG, "ioctl(SIOCGIFMEDIA) on %s: %m",
			       ifname);
			ifinfo->noifmedia = 1;
			goto active;
		}
		/*
		 * EINVAL (or ENOTTY) simply means that the interface 
		 * does not support the SIOCGIFMEDIA ioctl. We regard it alive.
		 */
		ifinfo->noifmedia = 1;
		goto active;
	}
	if (ifmr.ifm_status & IFM_AVALID) {
		switch(ifmr.ifm_active & IFM_NMASK) {
		case IFM_ETHER:
			if (ifmr.ifm_status & IFM_ACTIVE)
				goto active;
			else
				goto inactive;
			break;
		default:
			goto inactive;
		}
	}
 inactive:
	return(0);
 active:
	return(1);
}

int locate_network (packet)
	struct packet *packet;
{
	struct iaddr ia;

	/* If this came through a gateway, find the corresponding subnet... */
	if (packet -> raw -> giaddr.s_addr) {
		struct subnet *subnet;
		ia.len = 4;
		memcpy (ia.iabuf, &packet -> raw -> giaddr, 4);
		subnet = find_subnet (ia);
		if (subnet)
			packet -> shared_network = subnet -> shared_network;
		else
			packet -> shared_network = (struct shared_network *)0;
	} else {
		packet -> shared_network =
			packet -> interface -> shared_network;
	}
	if (packet -> shared_network)
		return 1;
	return 0;
}

void add_timeout (when, where, what)
	TIME when;
	void (*where) PROTO ((void *));
	void *what;
{
	struct timeout *t, *q;

	/* See if this timeout supersedes an existing timeout. */
	t = (struct timeout *)0;
	for (q = timeouts; q; q = q -> next) {
		if (q -> func == where && q -> what == what) {
			if (t)
				t -> next = q -> next;
			else
				timeouts = q -> next;
			break;
		}
		t = q;
	}

	/* If we didn't supersede a timeout, allocate a timeout
	   structure now. */
	if (!q) {
		if (free_timeouts) {
			q = free_timeouts;
			free_timeouts = q -> next;
			q -> func = where;
			q -> what = what;
		} else {
			q = (struct timeout *)malloc (sizeof (struct timeout));
			if (!q)
				error ("Can't allocate timeout structure!");
			q -> func = where;
			q -> what = what;
		}
	}

	q -> when = when;

	/* Now sort this timeout into the timeout list. */

	/* Beginning of list? */
	if (!timeouts || timeouts -> when > q -> when) {
		q -> next = timeouts;
		timeouts = q;
		return;
	}

	/* Middle of list? */
	for (t = timeouts; t -> next; t = t -> next) {
		if (t -> next -> when > q -> when) {
			q -> next = t -> next;
			t -> next = q;
			return;
		}
	}

	/* End of list. */
	t -> next = q;
	q -> next = (struct timeout *)0;
}

void cancel_timeout (where, what)
	void (*where) PROTO ((void *));
	void *what;
{
	struct timeout *t, *q;

	/* Look for this timeout on the list, and unlink it if we find it. */
	t = (struct timeout *)0;
	for (q = timeouts; q; q = q -> next) {
		if (q -> func == where && q -> what == what) {
			if (t)
				t -> next = q -> next;
			else
				timeouts = q -> next;
			break;
		}
		t = q;
	}

	/* If we found the timeout, put it on the free list. */
	if (q) {
		q -> next = free_timeouts;
		free_timeouts = q;
	}
}

/* Add a protocol to the list of protocols... */
void add_protocol (name, fd, handler, local)
	char *name;
	int fd;
	void (*handler) PROTO ((struct protocol *));
	void *local;
{
	struct protocol *p;

	p = (struct protocol *)malloc (sizeof *p);
	if (!p)
		error ("can't allocate protocol struct for %s", name);

	p -> fd = fd;
	p -> handler = handler;
	p -> local = local;

	p -> next = protocols;
	protocols = p;
}

void remove_protocol (proto)
	struct protocol *proto;
{
	struct protocol *p, *next, *prev;

	prev = (struct protocol *)0;
	for (p = protocols; p; p = next) {
		next = p -> next;
		if (p == proto) {
			if (prev)
				prev -> next = p -> next;
			else
				protocols = p -> next;
			free (p);
		}
	}
}