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freebsd-skq/sbin/routed/rdisc.c

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/*
* Copyright (c) 1995
* The Regents of the University of California. 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.
* 4. Neither the name of the University 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 REGENTS 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 REGENTS 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.
*
* $FreeBSD$
*/
#include "defs.h"
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#ifdef __NetBSD__
__RCSID("$NetBSD$");
#elif defined(__FreeBSD__)
__RCSID("$FreeBSD$");
#else
__RCSID("$Revision: 2.27 $");
#ident "$Revision: 2.27 $"
#endif
/* router advertisement ICMP packet */
struct icmp_ad {
u_int8_t icmp_type; /* type of message */
u_int8_t icmp_code; /* type sub code */
u_int16_t icmp_cksum; /* ones complement cksum of struct */
u_int8_t icmp_ad_num; /* # of following router addresses */
u_int8_t icmp_ad_asize; /* 2--words in each advertisement */
u_int16_t icmp_ad_life; /* seconds of validity */
struct icmp_ad_info {
n_long icmp_ad_addr;
n_long icmp_ad_pref;
} icmp_ad_info[1];
};
/* router solicitation ICMP packet */
struct icmp_so {
u_int8_t icmp_type; /* type of message */
u_int8_t icmp_code; /* type sub code */
u_int16_t icmp_cksum; /* ones complement cksum of struct */
n_long icmp_so_rsvd;
};
union ad_u {
struct icmp icmp;
struct icmp_ad ad;
struct icmp_so so;
};
int rdisc_sock = -1; /* router-discovery raw socket */
static const struct interface *rdisc_sock_mcast; /* current multicast interface */
struct timeval rdisc_timer;
int rdisc_ok; /* using solicited route */
#define MAX_ADS 16 /* at least one per interface */
struct dr { /* accumulated advertisements */
struct interface *dr_ifp;
naddr dr_gate; /* gateway */
time_t dr_ts; /* when received */
time_t dr_life; /* lifetime in host byte order */
n_long dr_recv_pref; /* received but biased preference */
n_long dr_pref; /* preference adjusted by metric */
};
static const struct dr *cur_drp;
static struct dr drs[MAX_ADS];
/* convert between signed, balanced around zero,
* and unsigned zero-based preferences */
#define SIGN_PREF(p) ((p) ^ MIN_PreferenceLevel)
#define UNSIGN_PREF(p) SIGN_PREF(p)
/* adjust unsigned preference by interface metric,
* without driving it to infinity */
#define PREF(p, ifp) ((int)(p) <= ((ifp)->int_metric+(ifp)->int_adj_outmetric)\
? ((p) != 0 ? 1 : 0) \
: (p) - ((ifp)->int_metric+(ifp)->int_adj_outmetric))
static void rdisc_sort(void);
/* dump an ICMP Router Discovery Advertisement Message
*/
static void
trace_rdisc(const char *act,
naddr from,
naddr to,
struct interface *ifp,
union ad_u *p,
u_int len)
{
int i;
n_long *wp, *lim;
if (!TRACEPACKETS || ftrace == 0)
return;
lastlog();
if (p->icmp.icmp_type == ICMP_ROUTERADVERT) {
(void)fprintf(ftrace, "%s Router Ad"
" from %s to %s via %s life=%d\n",
act, naddr_ntoa(from), naddr_ntoa(to),
ifp ? ifp->int_name : "?",
ntohs(p->ad.icmp_ad_life));
if (!TRACECONTENTS)
return;
wp = &p->ad.icmp_ad_info[0].icmp_ad_addr;
lim = &wp[(len - sizeof(p->ad)) / sizeof(*wp)];
for (i = 0; i < p->ad.icmp_ad_num && wp <= lim; i++) {
(void)fprintf(ftrace, "\t%s preference=%d",
naddr_ntoa(wp[0]), (int)ntohl(wp[1]));
wp += p->ad.icmp_ad_asize;
}
(void)fputc('\n',ftrace);
} else {
trace_act("%s Router Solic. from %s to %s via %s value=%#x",
act, naddr_ntoa(from), naddr_ntoa(to),
ifp ? ifp->int_name : "?",
(int)ntohl(p->so.icmp_so_rsvd));
}
}
/* prepare Router Discovery socket.
*/
static void
get_rdisc_sock(void)
{
if (rdisc_sock < 0) {
rdisc_sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
if (rdisc_sock < 0)
BADERR(1,"rdisc_sock = socket()");
fix_sock(rdisc_sock,"rdisc_sock");
fix_select();
}
}
/* Pick multicast group for router-discovery socket
*/
void
set_rdisc_mg(struct interface *ifp,
int on) /* 0=turn it off */
{
struct group_req gr;
struct sockaddr_in *sin;
assert(ifp != NULL);
if (rdisc_sock < 0) {
/* Create the raw socket so that we can hear at least
* broadcast router discovery packets.
*/
if ((ifp->int_state & IS_NO_RDISC) == IS_NO_RDISC
|| !on)
return;
get_rdisc_sock();
}
if (!(ifp->int_if_flags & IFF_MULTICAST)) {
ifp->int_state &= ~(IS_ALL_HOSTS | IS_ALL_ROUTERS);
return;
}
memset(&gr, 0, sizeof(gr));
gr.gr_interface = ifp->int_index;
sin = (struct sockaddr_in *)&gr.gr_group;
sin->sin_family = AF_INET;
#ifdef _HAVE_SIN_LEN
sin->sin_len = sizeof(struct sockaddr_in);
#endif
if (supplier
|| (ifp->int_state & IS_NO_ADV_IN)
|| !on) {
/* stop listening to advertisements
*/
if (ifp->int_state & IS_ALL_HOSTS) {
sin->sin_addr.s_addr = htonl(INADDR_ALLHOSTS_GROUP);
if (setsockopt(rdisc_sock, IPPROTO_IP,
MCAST_LEAVE_GROUP,
&gr, sizeof(gr)) < 0)
LOGERR("MCAST_LEAVE_GROUP ALLHOSTS");
ifp->int_state &= ~IS_ALL_HOSTS;
}
} else if (!(ifp->int_state & IS_ALL_HOSTS)) {
/* start listening to advertisements
*/
sin->sin_addr.s_addr = htonl(INADDR_ALLHOSTS_GROUP);
if (setsockopt(rdisc_sock, IPPROTO_IP, MCAST_JOIN_GROUP,
&gr, sizeof(gr)) < 0) {
LOGERR("MCAST_JOIN_GROUP ALLHOSTS");
} else {
ifp->int_state |= IS_ALL_HOSTS;
}
}
if (!supplier
|| (ifp->int_state & IS_NO_ADV_OUT)
|| !on) {
/* stop listening to solicitations
*/
if (ifp->int_state & IS_ALL_ROUTERS) {
sin->sin_addr.s_addr = htonl(INADDR_ALLROUTERS_GROUP);
if (setsockopt(rdisc_sock, IPPROTO_IP,
MCAST_LEAVE_GROUP,
&gr, sizeof(gr)) < 0)
LOGERR("MCAST_LEAVE_GROUP ALLROUTERS");
ifp->int_state &= ~IS_ALL_ROUTERS;
}
} else if (!(ifp->int_state & IS_ALL_ROUTERS)) {
/* start hearing solicitations
*/
sin->sin_addr.s_addr = htonl(INADDR_ALLROUTERS_GROUP);
if (setsockopt(rdisc_sock, IPPROTO_IP, MCAST_JOIN_GROUP,
&gr, sizeof(gr)) < 0) {
LOGERR("MCAST_JOIN_GROUP ALLROUTERS");
} else {
ifp->int_state |= IS_ALL_ROUTERS;
}
}
}
/* start supplying routes
*/
void
set_supplier(void)
{
struct interface *ifp;
struct dr *drp;
if (supplier_set)
return;
trace_act("start supplying routes");
/* Forget discovered routes.
*/
for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
drp->dr_recv_pref = 0;
drp->dr_life = 0;
}
rdisc_age(0);
supplier_set = 1;
supplier = 1;
/* Do not start advertising until we have heard some RIP routes */
LIM_SEC(rdisc_timer, now.tv_sec+MIN_WAITTIME);
/* Switch router discovery multicast groups from soliciting
* to advertising.
*/
LIST_FOREACH(ifp, &ifnet, int_list) {
if (ifp->int_state & IS_BROKE)
continue;
ifp->int_rdisc_cnt = 0;
ifp->int_rdisc_timer.tv_usec = rdisc_timer.tv_usec;
ifp->int_rdisc_timer.tv_sec = now.tv_sec+MIN_WAITTIME;
set_rdisc_mg(ifp, 1);
}
/* get rid of any redirects */
del_redirects(0,0);
}
/* age discovered routes and find the best one
*/
void
rdisc_age(naddr bad_gate)
{
time_t sec;
struct dr *drp;
/* If only advertising, then do only that. */
if (supplier) {
/* If switching from client to server, get rid of old
* default routes.
*/
if (cur_drp != 0)
rdisc_sort();
rdisc_adv();
return;
}
/* If we are being told about a bad router,
* then age the discovered default route, and if there is
* no alternative, solicit a replacement.
*/
if (bad_gate != 0) {
/* Look for the bad discovered default route.
* Age it and note its interface.
*/
for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
if (drp->dr_ts == 0)
continue;
/* When we find the bad router, then age the route
* to at most SUPPLY_INTERVAL.
* This is contrary to RFC 1256, but defends against
* black holes.
*/
if (drp->dr_gate == bad_gate) {
sec = (now.tv_sec - drp->dr_life
+ SUPPLY_INTERVAL);
if (drp->dr_ts > sec) {
trace_act("age 0.0.0.0 --> %s via %s",
naddr_ntoa(drp->dr_gate),
drp->dr_ifp->int_name);
drp->dr_ts = sec;
}
break;
}
}
}
rdisc_sol();
rdisc_sort();
/* Delete old redirected routes to keep the kernel table small,
* and to prevent black holes. Check that the kernel table
* matches the daemon table (i.e. has the default route).
* But only if RIP is not running and we are not dealing with
* a bad gateway, since otherwise age() will be called.
*/
if (rip_sock < 0 && bad_gate == 0)
age(0);
}
/* Zap all routes discovered via an interface that has gone bad
* This should only be called when !(ifp->int_state & IS_ALIAS)
*/
void
if_bad_rdisc(struct interface *ifp)
{
struct dr *drp;
for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
if (drp->dr_ifp != ifp)
continue;
drp->dr_recv_pref = 0;
drp->dr_ts = 0;
drp->dr_life = 0;
}
/* make a note to re-solicit, turn RIP on or off, etc. */
rdisc_timer.tv_sec = 0;
}
/* mark an interface ok for router discovering.
*/
void
if_ok_rdisc(struct interface *ifp)
{
set_rdisc_mg(ifp, 1);
ifp->int_rdisc_cnt = 0;
ifp->int_rdisc_timer.tv_sec = now.tv_sec + (supplier
? MIN_WAITTIME
: MAX_SOLICITATION_DELAY);
if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >))
rdisc_timer = ifp->int_rdisc_timer;
}
/* get rid of a dead discovered router
*/
static void
del_rdisc(struct dr *drp)
{
struct interface *ifp;
naddr gate;
int i;
del_redirects(gate = drp->dr_gate, 0);
drp->dr_ts = 0;
drp->dr_life = 0;
/* Count the other discovered routes on the interface.
*/
i = 0;
ifp = drp->dr_ifp;
for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
if (drp->dr_ts != 0
&& drp->dr_ifp == ifp)
i++;
}
/* If that was the last good discovered router on the interface,
* then solicit a new one.
* This is contrary to RFC 1256, but defends against black holes.
*/
if (i != 0) {
trace_act("discovered router %s via %s"
" is bad--have %d remaining",
naddr_ntoa(gate), ifp->int_name, i);
} else if (ifp->int_rdisc_cnt >= MAX_SOLICITATIONS) {
trace_act("last discovered router %s via %s"
" is bad--re-solicit",
naddr_ntoa(gate), ifp->int_name);
ifp->int_rdisc_cnt = 0;
ifp->int_rdisc_timer.tv_sec = 0;
rdisc_sol();
} else {
trace_act("last discovered router %s via %s"
" is bad--wait to solicit",
naddr_ntoa(gate), ifp->int_name);
}
}
/* Find the best discovered route,
* and discard stale routers.
*/
static void
rdisc_sort(void)
{
struct dr *drp, *new_drp;
struct rt_entry *rt;
struct rt_spare new;
struct interface *ifp;
u_int new_st = 0;
n_long new_pref = 0;
/* Find the best discovered route.
*/
new_drp = 0;
for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
if (drp->dr_ts == 0)
continue;
ifp = drp->dr_ifp;
/* Get rid of expired discovered routers.
*/
if (drp->dr_ts + drp->dr_life <= now.tv_sec) {
del_rdisc(drp);
continue;
}
LIM_SEC(rdisc_timer, drp->dr_ts+drp->dr_life+1);
/* Update preference with possibly changed interface
* metric.
*/
drp->dr_pref = PREF(drp->dr_recv_pref, ifp);
/* Prefer the current route to prevent thrashing.
* Prefer shorter lifetimes to speed the detection of
* bad routers.
* Avoid sick interfaces.
*/
if (new_drp == 0
|| (!((new_st ^ drp->dr_ifp->int_state) & IS_SICK)
&& (new_pref < drp->dr_pref
|| (new_pref == drp->dr_pref
&& (drp == cur_drp
|| (new_drp != cur_drp
&& new_drp->dr_life > drp->dr_life)))))
|| ((new_st & IS_SICK)
&& !(drp->dr_ifp->int_state & IS_SICK))) {
new_drp = drp;
new_st = drp->dr_ifp->int_state;
new_pref = drp->dr_pref;
}
}
/* switch to a better default route
*/
if (new_drp != cur_drp) {
rt = rtget(RIP_DEFAULT, 0);
/* Stop using discovered routes if they are all bad
*/
if (new_drp == 0) {
trace_act("turn off Router Discovery client");
rdisc_ok = 0;
if (rt != 0
&& (rt->rt_state & RS_RDISC)) {
new = rt->rt_spares[0];
new.rts_metric = HOPCNT_INFINITY;
new.rts_time = now.tv_sec - GARBAGE_TIME;
rtchange(rt, rt->rt_state & ~RS_RDISC,
&new, 0);
rtswitch(rt, 0);
}
} else {
if (cur_drp == 0) {
trace_act("turn on Router Discovery client"
" using %s via %s",
naddr_ntoa(new_drp->dr_gate),
new_drp->dr_ifp->int_name);
rdisc_ok = 1;
} else {
trace_act("switch Router Discovery from"
" %s via %s to %s via %s",
naddr_ntoa(cur_drp->dr_gate),
cur_drp->dr_ifp->int_name,
naddr_ntoa(new_drp->dr_gate),
new_drp->dr_ifp->int_name);
}
memset(&new, 0, sizeof(new));
new.rts_ifp = new_drp->dr_ifp;
new.rts_gate = new_drp->dr_gate;
new.rts_router = new_drp->dr_gate;
new.rts_metric = HOPCNT_INFINITY-1;
new.rts_time = now.tv_sec;
if (rt != 0) {
rtchange(rt, rt->rt_state | RS_RDISC, &new, 0);
} else {
rtadd(RIP_DEFAULT, 0, RS_RDISC, &new);
}
}
cur_drp = new_drp;
}
/* turn RIP on or off */
if (!rdisc_ok || rip_interfaces > 1) {
rip_on(0);
} else {
rip_off();
}
}
/* handle a single address in an advertisement
*/
static void
parse_ad(naddr from,
naddr gate,
n_long pref, /* signed and in network order */
u_short life, /* in host byte order */
struct interface *ifp)
{
static struct msg_limit bad_gate;
struct dr *drp, *new_drp;
if (gate == RIP_DEFAULT
|| !check_dst(gate)) {
msglim(&bad_gate, from,"router %s advertising bad gateway %s",
naddr_ntoa(from),
naddr_ntoa(gate));
return;
}
/* ignore pointers to ourself and routes via unreachable networks
*/
if (ifwithaddr(gate, 1, 0) != 0) {
trace_pkt(" discard Router Discovery Ad pointing at us");
return;
}
if (!on_net(gate, ifp->int_net, ifp->int_mask)) {
trace_pkt(" discard Router Discovery Ad"
" toward unreachable net");
return;
}
/* Convert preference to an unsigned value
* and later bias it by the metric of the interface.
*/
pref = UNSIGN_PREF(ntohl(pref));
if (pref == 0 || life < MinMaxAdvertiseInterval) {
pref = 0;
life = 0;
}
for (new_drp = 0, drp = drs; drp < &drs[MAX_ADS]; drp++) {
/* accept new info for a familiar entry
*/
if (drp->dr_gate == gate) {
new_drp = drp;
break;
}
if (life == 0)
continue; /* do not worry about dead ads */
if (drp->dr_ts == 0) {
new_drp = drp; /* use unused entry */
} else if (new_drp == 0) {
/* look for an entry worse than the new one to
* reuse.
*/
if ((!(ifp->int_state & IS_SICK)
&& (drp->dr_ifp->int_state & IS_SICK))
|| (pref > drp->dr_pref
&& !((ifp->int_state ^ drp->dr_ifp->int_state)
& IS_SICK)))
new_drp = drp;
} else if (new_drp->dr_ts != 0) {
/* look for the least valuable entry to reuse
*/
if ((!(new_drp->dr_ifp->int_state & IS_SICK)
&& (drp->dr_ifp->int_state & IS_SICK))
|| (new_drp->dr_pref > drp->dr_pref
&& !((new_drp->dr_ifp->int_state
^ drp->dr_ifp->int_state)
& IS_SICK)))
new_drp = drp;
}
}
/* forget it if all of the current entries are better */
if (new_drp == 0)
return;
new_drp->dr_ifp = ifp;
new_drp->dr_gate = gate;
new_drp->dr_ts = now.tv_sec;
new_drp->dr_life = life;
new_drp->dr_recv_pref = pref;
/* bias functional preference by metric of the interface */
new_drp->dr_pref = PREF(pref,ifp);
/* after hearing a good advertisement, stop asking
*/
if (!(ifp->int_state & IS_SICK))
ifp->int_rdisc_cnt = MAX_SOLICITATIONS;
}
/* Compute the IP checksum
* This assumes the packet is less than 32K long.
*/
static u_short
in_cksum(u_short *p,
u_int len)
{
u_int sum = 0;
int nwords = len >> 1;
while (nwords-- != 0)
sum += *p++;
if (len & 1)
sum += *(u_char *)p;
/* end-around-carry */
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
return (~sum);
}
/* Send a router discovery advertisement or solicitation ICMP packet.
*/
static void
send_rdisc(union ad_u *p,
int p_size,
struct interface *ifp,
naddr dst, /* 0 or unicast destination */
int type) /* 0=unicast, 1=bcast, 2=mcast */
{
struct sockaddr_in rsin;
int flags;
const char *msg;
memset(&rsin, 0, sizeof(rsin));
rsin.sin_addr.s_addr = dst;
rsin.sin_family = AF_INET;
#ifdef _HAVE_SIN_LEN
rsin.sin_len = sizeof(rsin);
#endif
flags = MSG_DONTROUTE;
switch (type) {
case 0: /* unicast */
default:
msg = "Send";
break;
case 1: /* broadcast */
if (ifp->int_if_flags & IFF_POINTOPOINT) {
msg = "Send pt-to-pt";
rsin.sin_addr.s_addr = ifp->int_dstaddr;
} else {
msg = "Send broadcast";
rsin.sin_addr.s_addr = ifp->int_brdaddr;
}
break;
case 2: /* multicast */
msg = "Send multicast";
if (ifp->int_state & IS_DUP) {
trace_act("abort multicast output via %s"
" with duplicate address",
ifp->int_name);
return;
}
if (rdisc_sock_mcast != ifp) {
/* select the right interface. */
struct ip_mreqn mreqn;
memset(&mreqn, 0, sizeof(struct ip_mreqn));
mreqn.imr_ifindex = ifp->int_index;
if (0 > setsockopt(rdisc_sock,
IPPROTO_IP, IP_MULTICAST_IF,
&mreqn,
sizeof(mreqn))) {
LOGERR("setsockopt(rdisc_sock,"
"IP_MULTICAST_IF)");
rdisc_sock_mcast = 0;
return;
}
rdisc_sock_mcast = ifp;
}
flags = 0;
break;
}
if (rdisc_sock < 0)
get_rdisc_sock();
trace_rdisc(msg, ifp->int_addr, rsin.sin_addr.s_addr, ifp,
p, p_size);
if (0 > sendto(rdisc_sock, p, p_size, flags,
(struct sockaddr *)&rsin, sizeof(rsin))) {
if (ifp == 0 || !(ifp->int_state & IS_BROKE))
msglog("sendto(%s%s%s): %s",
ifp != 0 ? ifp->int_name : "",
ifp != 0 ? ", " : "",
inet_ntoa(rsin.sin_addr),
strerror(errno));
if (ifp != 0)
if_sick(ifp);
}
}
/* Send an advertisement
*/
static void
send_adv(struct interface *ifp,
naddr dst, /* 0 or unicast destination */
int type) /* 0=unicast, 1=bcast, 2=mcast */
{
union ad_u u;
n_long pref;
memset(&u, 0, sizeof(u.ad));
u.ad.icmp_type = ICMP_ROUTERADVERT;
u.ad.icmp_ad_num = 1;
u.ad.icmp_ad_asize = sizeof(u.ad.icmp_ad_info[0])/4;
u.ad.icmp_ad_life = stopint ? 0 : htons(ifp->int_rdisc_int*3);
/* Convert the configured preference to an unsigned value,
* bias it by the interface metric, and then send it as a
* signed, network byte order value.
*/
pref = UNSIGN_PREF(ifp->int_rdisc_pref);
u.ad.icmp_ad_info[0].icmp_ad_pref = htonl(SIGN_PREF(PREF(pref, ifp)));
u.ad.icmp_ad_info[0].icmp_ad_addr = ifp->int_addr;
u.ad.icmp_cksum = in_cksum((u_short*)&u.ad, sizeof(u.ad));
send_rdisc(&u, sizeof(u.ad), ifp, dst, type);
}
/* Advertise for Router Discovery
*/
void
rdisc_adv(void)
{
struct interface *ifp;
if (!supplier)
return;
rdisc_timer.tv_sec = now.tv_sec + NEVER;
LIST_FOREACH(ifp, &ifnet, int_list) {
if (0 != (ifp->int_state & (IS_NO_ADV_OUT | IS_BROKE)))
continue;
if (!timercmp(&ifp->int_rdisc_timer, &now, >)
|| stopint) {
send_adv(ifp, htonl(INADDR_ALLHOSTS_GROUP),
(ifp->int_state&IS_BCAST_RDISC) ? 1 : 2);
ifp->int_rdisc_cnt++;
intvl_random(&ifp->int_rdisc_timer,
(ifp->int_rdisc_int*3)/4,
ifp->int_rdisc_int);
if (ifp->int_rdisc_cnt < MAX_INITIAL_ADVERTS
&& (ifp->int_rdisc_timer.tv_sec
> MAX_INITIAL_ADVERT_INTERVAL)) {
ifp->int_rdisc_timer.tv_sec
= MAX_INITIAL_ADVERT_INTERVAL;
}
timevaladd(&ifp->int_rdisc_timer, &now);
}
if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >))
rdisc_timer = ifp->int_rdisc_timer;
}
}
/* Solicit for Router Discovery
*/
void
rdisc_sol(void)
{
struct interface *ifp;
union ad_u u;
if (supplier)
return;
rdisc_timer.tv_sec = now.tv_sec + NEVER;
LIST_FOREACH(ifp, &ifnet, int_list) {
if (0 != (ifp->int_state & (IS_NO_SOL_OUT | IS_BROKE))
|| ifp->int_rdisc_cnt >= MAX_SOLICITATIONS)
continue;
if (!timercmp(&ifp->int_rdisc_timer, &now, >)) {
memset(&u, 0, sizeof(u.so));
u.so.icmp_type = ICMP_ROUTERSOLICIT;
u.so.icmp_cksum = in_cksum((u_short*)&u.so,
sizeof(u.so));
send_rdisc(&u, sizeof(u.so), ifp,
htonl(INADDR_ALLROUTERS_GROUP),
((ifp->int_state&IS_BCAST_RDISC) ? 1 : 2));
if (++ifp->int_rdisc_cnt >= MAX_SOLICITATIONS)
continue;
ifp->int_rdisc_timer.tv_sec = SOLICITATION_INTERVAL;
ifp->int_rdisc_timer.tv_usec = 0;
timevaladd(&ifp->int_rdisc_timer, &now);
}
if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >))
rdisc_timer = ifp->int_rdisc_timer;
}
}
/* check the IP header of a possible Router Discovery ICMP packet */
static struct interface * /* 0 if bad */
ck_icmp(const char *act,
naddr from,
struct interface *ifp,
naddr to,
union ad_u *p,
u_int len)
{
const char *type;
if (p->icmp.icmp_type == ICMP_ROUTERADVERT) {
type = "advertisement";
} else if (p->icmp.icmp_type == ICMP_ROUTERSOLICIT) {
type = "solicitation";
} else {
return 0;
}
if (p->icmp.icmp_code != 0) {
trace_pkt("unrecognized ICMP Router %s code=%d from %s to %s",
type, p->icmp.icmp_code,
naddr_ntoa(from), naddr_ntoa(to));
return 0;
}
trace_rdisc(act, from, to, ifp, p, len);
if (ifp == 0)
trace_pkt("unknown interface for router-discovery %s"
" from %s to %s",
type, naddr_ntoa(from), naddr_ntoa(to));
return ifp;
}
/* read packets from the router discovery socket
*/
void
read_d(void)
{
static struct msg_limit bad_asize, bad_len;
#ifdef USE_PASSIFNAME
static struct msg_limit bad_name;
#endif
struct sockaddr_in from;
int n, fromlen, cc, hlen;
struct {
#ifdef USE_PASSIFNAME
char ifname[IFNAMSIZ];
#endif
union {
struct ip ip;
u_char b[512];
} pkt;
} buf;
union ad_u *p;
n_long *wp;
struct interface *ifp;
for (;;) {
fromlen = sizeof(from);
cc = recvfrom(rdisc_sock, &buf, sizeof(buf), 0,
(struct sockaddr*)&from,
&fromlen);
if (cc <= 0) {
if (cc < 0 && errno != EWOULDBLOCK)
LOGERR("recvfrom(rdisc_sock)");
break;
}
if (fromlen != sizeof(struct sockaddr_in))
logbad(1,"impossible recvfrom(rdisc_sock) fromlen=%d",
fromlen);
#ifdef USE_PASSIFNAME
if ((cc -= sizeof(buf.ifname)) < 0)
logbad(0,"missing USE_PASSIFNAME; only %d bytes",
cc+sizeof(buf.ifname));
#endif
hlen = buf.pkt.ip.ip_hl << 2;
if (cc < hlen + ICMP_MINLEN)
continue;
p = (union ad_u *)&buf.pkt.b[hlen];
cc -= hlen;
#ifdef USE_PASSIFNAME
ifp = ifwithname(buf.ifname, 0);
if (ifp == 0)
msglim(&bad_name, from.sin_addr.s_addr,
"impossible rdisc if_ name %.*s",
IFNAMSIZ, buf.ifname);
#else
/* If we could tell the interface on which a packet from
* address 0 arrived, we could deal with such solicitations.
*/
ifp = ((from.sin_addr.s_addr == 0)
? 0 : iflookup(from.sin_addr.s_addr));
#endif
ifp = ck_icmp("Recv", from.sin_addr.s_addr, ifp,
buf.pkt.ip.ip_dst.s_addr, p, cc);
if (ifp == 0)
continue;
if (ifwithaddr(from.sin_addr.s_addr, 0, 0)) {
trace_pkt(" "
"discard our own Router Discovery message");
continue;
}
switch (p->icmp.icmp_type) {
case ICMP_ROUTERADVERT:
if (p->ad.icmp_ad_asize*4
< (int)sizeof(p->ad.icmp_ad_info[0])) {
msglim(&bad_asize, from.sin_addr.s_addr,
"intolerable rdisc address size=%d",
p->ad.icmp_ad_asize);
continue;
}
if (p->ad.icmp_ad_num == 0) {
trace_pkt(" empty?");
continue;
}
if (cc != (int)(sizeof(p->ad)
- sizeof(p->ad.icmp_ad_info)
+ (p->ad.icmp_ad_num
* sizeof(p->ad.icmp_ad_info[0])))) {
msglim(&bad_len, from.sin_addr.s_addr,
"rdisc length %d does not match ad_num"
" %d", cc, p->ad.icmp_ad_num);
continue;
}
if (supplier)
continue;
if (ifp->int_state & IS_NO_ADV_IN)
continue;
wp = &p->ad.icmp_ad_info[0].icmp_ad_addr;
for (n = 0; n < p->ad.icmp_ad_num; n++) {
parse_ad(from.sin_addr.s_addr,
wp[0], wp[1],
ntohs(p->ad.icmp_ad_life),
ifp);
wp += p->ad.icmp_ad_asize;
}
break;
case ICMP_ROUTERSOLICIT:
if (!supplier)
continue;
if (ifp->int_state & IS_NO_ADV_OUT)
continue;
if (stopint)
continue;
/* XXX
* We should handle messages from address 0.
*/
/* Respond with a point-to-point advertisement */
send_adv(ifp, from.sin_addr.s_addr, 0);
break;
}
}
rdisc_sort();
}
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