OpenBSD-4.6/usr.sbin/dhcpd/dispatch.c
/* $OpenBSD: dispatch.c,v 1.24 2008/09/15 20:38:17 claudio Exp $ */
/*
* 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 "sync.h"
#include <ifaddrs.h>
#include <sys/ioctl.h>
#include <poll.h>
#include <net/if_media.h>
extern int syncfd;
struct interface_info *interfaces;
struct protocol *protocols;
struct dhcpd_timeout *timeouts;
static struct dhcpd_timeout *free_timeouts;
static int interfaces_invalidated;
void (*bootp_packet_handler)(struct interface_info *,
struct dhcp_packet *, int, unsigned int, struct iaddr, struct hardware *);
static int interface_status(struct interface_info *ifinfo);
/* Use getifaddrs() 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(void)
{
struct interface_info *tmp;
struct interface_info *last, *next;
struct subnet *subnet;
struct shared_network *share;
struct sockaddr_in foo;
int ir = 0;
struct ifreq *tif;
struct ifaddrs *ifap, *ifa;
if (getifaddrs(&ifap) != 0)
error("getifaddrs failed");
/*
* If we already have a list of interfaces, the interfaces were
* requested.
*/
if (interfaces != NULL)
ir = 1;
/* 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)))
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 we are looking for specific interfaces, ignore others. */
if (tmp == NULL && ir)
continue;
/* If there isn't already an interface by this name,
allocate one. */
if (tmp == NULL) {
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->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->index = foo->sdl_index;
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) {
warning("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) {
warning("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) {
warning("Multiple %s %s: %s %s",
"interfaces match the",
"same shared network",
share->interface->name,
tmp->name);
}
}
}
}
/* Discard interfaces we can't listen on. */
last = NULL;
for (tmp = interfaces; tmp; tmp = next) {
next = tmp->next;
if (!tmp->ifp) {
warning("Can't listen on %s - it has no IP address.",
tmp->name);
/* Remove tmp from the list of interfaces. */
if (!last)
interfaces = interfaces->next;
else
last->next = tmp->next;
continue;
}
memcpy(&foo, &tmp->ifp->ifr_addr, sizeof tmp->ifp->ifr_addr);
if (!tmp->shared_network) {
warning("Can't listen on %s - dhcpd.conf has no subnet "
"declaration for %s.", tmp->name,
inet_ntoa(foo.sin_addr));
/* Remove tmp from the list of interfaces. */
if (!last)
interfaces = interfaces->next;
else
last->next = tmp->next;
continue;
}
last = tmp;
/* Find subnets that don't have valid interface addresses. */
for (subnet = (tmp->shared_network ? tmp->shared_network->subnets :
NULL); 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);
}
if (interfaces == NULL)
error("No interfaces to listen on.");
/* Now register all the remaining interfaces as protocols. */
for (tmp = interfaces; tmp; tmp = tmp->next)
add_protocol(tmp->name, tmp->rfdesc, got_one, tmp);
freeifaddrs(ifap);
}
/*
* 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(void)
{
int nfds, i, to_msec;
struct protocol *l;
static struct pollfd *fds;
static int nfds_max;
time_t howlong;
for (nfds = 0, l = protocols; l; l = l->next)
nfds++;
if (syncfd != -1)
nfds++;
if (nfds > nfds_max) {
fds = realloc(fds, nfds * sizeof(struct pollfd));
if (fds == NULL)
error("Can't allocate poll structures.");
nfds_max = nfds;
}
for (;;) {
/*
* Call any expired timeouts, and then if there's
* still a timeout registered, time out the poll
* call then.
*/
time(&cur_time);
another:
if (timeouts) {
if (timeouts->when <= cur_time) {
struct dhcpd_timeout *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 indefinitely.
*/
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. */
for (i = 0, 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;
++i;
}
}
if (i == 0)
error("No live interfaces to poll on - exiting.");
if (syncfd != -1) {
/* add syncer */
fds[i].fd = syncfd;
fds[i].events = POLLIN;
}
/* Wait for a packet or a timeout... */
switch (poll(fds, nfds, to_msec)) {
case -1:
if (errno != EAGAIN && errno != EINTR)
error("poll: %m");
/* FALLTHROUGH */
case 0:
continue; /* no packets */
}
for (i = 0, l = protocols; l; l = l->next) {
struct interface_info *ip = l->local;
if ((fds[i].revents & (POLLIN | POLLHUP))) {
if (ip && (l->handler != got_one ||
!ip->dead))
(*(l->handler))(l);
if (interfaces_invalidated)
break;
}
++i;
}
if ((syncfd != -1) && (fds[i].revents & (POLLIN | POLLHUP)))
sync_recv();
interfaces_invalidated = 0;
}
}
void
got_one(struct protocol *l)
{
struct sockaddr_in from;
struct hardware hfrom;
struct iaddr ifrom;
ssize_t result;
union {
unsigned char packbuf[4095];
struct dhcp_packet packet;
} u;
struct interface_info *ip = l->local;
if ((result = receive_packet(ip, u.packbuf, sizeof u,
&from, &hfrom)) == -1) {
warning("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. */
warning("Interface %s no longer appears valid.",
ip->name);
ip->dead = 1;
interfaces_invalidated = 1;
close(l->fd);
remove_protocol(l);
free(ip);
}
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) == -1) {
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) == -1) {
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(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 = NULL;
} else {
packet->shared_network = packet->interface->shared_network;
}
if (packet->shared_network)
return 1;
return 0;
}
void
add_timeout(time_t when, void (*where)(void *), void *what)
{
struct dhcpd_timeout *t, *q;
/* See if this timeout supersedes an existing timeout. */
t = NULL;
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 dhcpd_timeout *)malloc(sizeof (struct dhcpd_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 = NULL;
}
void
cancel_timeout(void (*where)(void *), void *what)
{
struct dhcpd_timeout *t, *q;
/* Look for this timeout on the list, and unlink it if we find it. */
t = NULL;
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(char *name, int fd, void (*handler)(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(struct protocol *proto)
{
struct protocol *p, *next, *prev = NULL;
for (p = protocols; p; p = next) {
next = p->next;
if (p == proto) {
if (prev)
prev->next = p->next;
else
protocols = p->next;
free(p);
}
}
}