FreeBSD-5.3/sys/netinet/igmp.c
/*
* Copyright (c) 1988 Stephen Deering.
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Stephen Deering of Stanford University.
*
* 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.
*
* @(#)igmp.c 8.1 (Berkeley) 7/19/93
* $FreeBSD: src/sys/netinet/igmp.c,v 1.46 2004/06/11 03:42:37 rwatson Exp $
*/
/*
* Internet Group Management Protocol (IGMP) routines.
*
* Written by Steve Deering, Stanford, May 1988.
* Modified by Rosen Sharma, Stanford, Aug 1994.
* Modified by Bill Fenner, Xerox PARC, Feb 1995.
* Modified to fully comply to IGMPv2 by Bill Fenner, Oct 1995.
*
* MULTICAST Revision: 3.5.1.4
*/
#include "opt_mac.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mac.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/protosw.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/igmp.h>
#include <netinet/igmp_var.h>
#include <machine/in_cksum.h>
static MALLOC_DEFINE(M_IGMP, "igmp", "igmp state");
static struct router_info *find_rti(struct ifnet *ifp);
static void igmp_sendpkt(struct in_multi *, int, unsigned long);
static struct igmpstat igmpstat;
SYSCTL_STRUCT(_net_inet_igmp, IGMPCTL_STATS, stats, CTLFLAG_RW, &igmpstat,
igmpstat, "");
/*
* igmp_mtx protects all mutable global variables in igmp.c, as well as
* the data fields in struct router_info. In general, a router_info
* structure will be valid as long as the referencing struct in_multi is
* valid, so no reference counting is used. We allow unlocked reads of
* router_info data when accessed via an in_multi read-only.
*/
static struct mtx igmp_mtx;
static SLIST_HEAD(, router_info) router_info_head;
static int igmp_timers_are_running;
/*
* XXXRW: can we define these such that these can be made const? In any
* case, these shouldn't be changed after igmp_init() and therefore don't
* need locking.
*/
static u_long igmp_all_hosts_group;
static u_long igmp_all_rtrs_group;
static struct mbuf *router_alert;
static struct route igmprt;
#ifdef IGMP_DEBUG
#define IGMP_PRINTF(x) printf(x)
#else
#define IGMP_PRINTF(x)
#endif
void
igmp_init(void)
{
struct ipoption *ra;
/*
* To avoid byte-swapping the same value over and over again.
*/
igmp_all_hosts_group = htonl(INADDR_ALLHOSTS_GROUP);
igmp_all_rtrs_group = htonl(INADDR_ALLRTRS_GROUP);
igmp_timers_are_running = 0;
/*
* Construct a Router Alert option to use in outgoing packets
*/
MGET(router_alert, M_DONTWAIT, MT_DATA);
ra = mtod(router_alert, struct ipoption *);
ra->ipopt_dst.s_addr = 0;
ra->ipopt_list[0] = IPOPT_RA; /* Router Alert Option */
ra->ipopt_list[1] = 0x04; /* 4 bytes long */
ra->ipopt_list[2] = 0x00;
ra->ipopt_list[3] = 0x00;
router_alert->m_len = sizeof(ra->ipopt_dst) + ra->ipopt_list[1];
mtx_init(&igmp_mtx, "igmp_mtx", NULL, MTX_DEF);
SLIST_INIT(&router_info_head);
}
static struct router_info *
find_rti(struct ifnet *ifp)
{
struct router_info *rti;
mtx_assert(&igmp_mtx, MA_OWNED);
IGMP_PRINTF("[igmp.c, _find_rti] --> entering \n");
SLIST_FOREACH(rti, &router_info_head, rti_list) {
if (rti->rti_ifp == ifp) {
IGMP_PRINTF(
"[igmp.c, _find_rti] --> found old entry \n");
return rti;
}
}
/*
* XXXRW: return value of malloc not checked, despite M_NOWAIT.
*/
MALLOC(rti, struct router_info *, sizeof *rti, M_IGMP, M_NOWAIT);
rti->rti_ifp = ifp;
rti->rti_type = IGMP_V2_ROUTER;
rti->rti_time = 0;
SLIST_INSERT_HEAD(&router_info_head, rti, rti_list);
IGMP_PRINTF("[igmp.c, _find_rti] --> created an entry \n");
return rti;
}
void
igmp_input(register struct mbuf *m, int off)
{
register int iphlen = off;
register struct igmp *igmp;
register struct ip *ip;
register int igmplen;
register struct ifnet *ifp = m->m_pkthdr.rcvif;
register int minlen;
register struct in_multi *inm;
register struct in_ifaddr *ia;
struct in_multistep step;
struct router_info *rti;
int timer; /** timer value in the igmp query header **/
++igmpstat.igps_rcv_total;
ip = mtod(m, struct ip *);
igmplen = ip->ip_len;
/*
* Validate lengths
*/
if (igmplen < IGMP_MINLEN) {
++igmpstat.igps_rcv_tooshort;
m_freem(m);
return;
}
minlen = iphlen + IGMP_MINLEN;
if ((m->m_flags & M_EXT || m->m_len < minlen) &&
(m = m_pullup(m, minlen)) == 0) {
++igmpstat.igps_rcv_tooshort;
return;
}
/*
* Validate checksum
*/
m->m_data += iphlen;
m->m_len -= iphlen;
igmp = mtod(m, struct igmp *);
if (in_cksum(m, igmplen)) {
++igmpstat.igps_rcv_badsum;
m_freem(m);
return;
}
m->m_data -= iphlen;
m->m_len += iphlen;
ip = mtod(m, struct ip *);
timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE;
if (timer == 0)
timer = 1;
/*
* In the IGMPv2 specification, there are 3 states and a flag.
*
* In Non-Member state, we simply don't have a membership record.
* In Delaying Member state, our timer is running (inm->inm_timer)
* In Idle Member state, our timer is not running (inm->inm_timer==0)
*
* The flag is inm->inm_state, it is set to IGMP_OTHERMEMBER if
* we have heard a report from another member, or IGMP_IREPORTEDLAST
* if I sent the last report.
*/
switch (igmp->igmp_type) {
case IGMP_MEMBERSHIP_QUERY:
++igmpstat.igps_rcv_queries;
if (ifp->if_flags & IFF_LOOPBACK)
break;
if (igmp->igmp_code == 0) {
/*
* Old router. Remember that the querier on this
* interface is old, and set the timer to the
* value in RFC 1112.
*/
mtx_lock(&igmp_mtx);
rti = find_rti(ifp);
rti->rti_type = IGMP_V1_ROUTER;
rti->rti_time = 0;
mtx_unlock(&igmp_mtx);
timer = IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ;
if (ip->ip_dst.s_addr != igmp_all_hosts_group ||
igmp->igmp_group.s_addr != 0) {
++igmpstat.igps_rcv_badqueries;
m_freem(m);
return;
}
} else {
/*
* New router. Simply do the new validity check.
*/
if (igmp->igmp_group.s_addr != 0 &&
!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) {
++igmpstat.igps_rcv_badqueries;
m_freem(m);
return;
}
}
/*
* - Start the timers in all of our membership records
* that the query applies to for the interface on
* which the query arrived excl. those that belong
* to the "all-hosts" group (224.0.0.1).
* - Restart any timer that is already running but has
* a value longer than the requested timeout.
* - Use the value specified in the query message as
* the maximum timeout.
*/
IN_FIRST_MULTI(step, inm);
while (inm != NULL) {
if (inm->inm_ifp == ifp &&
inm->inm_addr.s_addr != igmp_all_hosts_group &&
(igmp->igmp_group.s_addr == 0 ||
igmp->igmp_group.s_addr == inm->inm_addr.s_addr)) {
if (inm->inm_timer == 0 ||
inm->inm_timer > timer) {
inm->inm_timer =
IGMP_RANDOM_DELAY(timer);
igmp_timers_are_running = 1;
}
}
IN_NEXT_MULTI(step, inm);
}
break;
case IGMP_V1_MEMBERSHIP_REPORT:
case IGMP_V2_MEMBERSHIP_REPORT:
/*
* For fast leave to work, we have to know that we are the
* last person to send a report for this group. Reports
* can potentially get looped back if we are a multicast
* router, so discard reports sourced by me.
*/
IFP_TO_IA(ifp, ia);
if (ia && ip->ip_src.s_addr == IA_SIN(ia)->sin_addr.s_addr)
break;
++igmpstat.igps_rcv_reports;
if (ifp->if_flags & IFF_LOOPBACK)
break;
if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr))) {
++igmpstat.igps_rcv_badreports;
m_freem(m);
return;
}
/*
* KLUDGE: if the IP source address of the report has an
* unspecified (i.e., zero) subnet number, as is allowed for
* a booting host, replace it with the correct subnet number
* so that a process-level multicast routing daemon can
* determine which subnet it arrived from. This is necessary
* to compensate for the lack of any way for a process to
* determine the arrival interface of an incoming packet.
*/
if ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) == 0)
if (ia) ip->ip_src.s_addr = htonl(ia->ia_subnet);
/*
* If we belong to the group being reported, stop
* our timer for that group.
*/
IN_LOOKUP_MULTI(igmp->igmp_group, ifp, inm);
if (inm != NULL) {
inm->inm_timer = 0;
++igmpstat.igps_rcv_ourreports;
inm->inm_state = IGMP_OTHERMEMBER;
}
break;
}
/*
* Pass all valid IGMP packets up to any process(es) listening
* on a raw IGMP socket.
*/
rip_input(m, off);
}
void
igmp_joingroup(struct in_multi *inm)
{
int s = splnet();
if (inm->inm_addr.s_addr == igmp_all_hosts_group
|| inm->inm_ifp->if_flags & IFF_LOOPBACK) {
inm->inm_timer = 0;
inm->inm_state = IGMP_OTHERMEMBER;
} else {
mtx_lock(&igmp_mtx);
inm->inm_rti = find_rti(inm->inm_ifp);
mtx_unlock(&igmp_mtx);
igmp_sendpkt(inm, inm->inm_rti->rti_type, 0);
inm->inm_timer = IGMP_RANDOM_DELAY(
IGMP_MAX_HOST_REPORT_DELAY*PR_FASTHZ);
inm->inm_state = IGMP_IREPORTEDLAST;
igmp_timers_are_running = 1;
}
splx(s);
}
void
igmp_leavegroup(struct in_multi *inm)
{
if (inm->inm_state == IGMP_IREPORTEDLAST &&
inm->inm_addr.s_addr != igmp_all_hosts_group &&
!(inm->inm_ifp->if_flags & IFF_LOOPBACK) &&
inm->inm_rti->rti_type != IGMP_V1_ROUTER)
igmp_sendpkt(inm, IGMP_V2_LEAVE_GROUP, igmp_all_rtrs_group);
}
void
igmp_fasttimo(void)
{
register struct in_multi *inm;
struct in_multistep step;
int s;
/*
* Quick check to see if any work needs to be done, in order
* to minimize the overhead of fasttimo processing.
*/
if (!igmp_timers_are_running)
return;
s = splnet();
igmp_timers_are_running = 0;
IN_FIRST_MULTI(step, inm);
while (inm != NULL) {
if (inm->inm_timer == 0) {
/* do nothing */
} else if (--inm->inm_timer == 0) {
igmp_sendpkt(inm, inm->inm_rti->rti_type, 0);
inm->inm_state = IGMP_IREPORTEDLAST;
} else {
igmp_timers_are_running = 1;
}
IN_NEXT_MULTI(step, inm);
}
splx(s);
}
void
igmp_slowtimo(void)
{
int s = splnet();
struct router_info *rti;
IGMP_PRINTF("[igmp.c,_slowtimo] -- > entering \n");
mtx_lock(&igmp_mtx);
SLIST_FOREACH(rti, &router_info_head, rti_list) {
if (rti->rti_type == IGMP_V1_ROUTER) {
rti->rti_time++;
if (rti->rti_time >= IGMP_AGE_THRESHOLD)
rti->rti_type = IGMP_V2_ROUTER;
}
}
mtx_unlock(&igmp_mtx);
IGMP_PRINTF("[igmp.c,_slowtimo] -- > exiting \n");
splx(s);
}
static void
igmp_sendpkt(struct in_multi *inm, int type, unsigned long addr)
{
struct mbuf *m;
struct igmp *igmp;
struct ip *ip;
struct ip_moptions imo;
MGETHDR(m, M_DONTWAIT, MT_HEADER);
if (m == NULL)
return;
m->m_pkthdr.rcvif = loif;
#ifdef MAC
mac_create_mbuf_linklayer(inm->inm_ifp, m);
#endif
m->m_pkthdr.len = sizeof(struct ip) + IGMP_MINLEN;
MH_ALIGN(m, IGMP_MINLEN + sizeof(struct ip));
m->m_data += sizeof(struct ip);
m->m_len = IGMP_MINLEN;
igmp = mtod(m, struct igmp *);
igmp->igmp_type = type;
igmp->igmp_code = 0;
igmp->igmp_group = inm->inm_addr;
igmp->igmp_cksum = 0;
igmp->igmp_cksum = in_cksum(m, IGMP_MINLEN);
m->m_data -= sizeof(struct ip);
m->m_len += sizeof(struct ip);
ip = mtod(m, struct ip *);
ip->ip_tos = 0;
ip->ip_len = sizeof(struct ip) + IGMP_MINLEN;
ip->ip_off = 0;
ip->ip_p = IPPROTO_IGMP;
ip->ip_src.s_addr = INADDR_ANY;
ip->ip_dst.s_addr = addr ? addr : igmp->igmp_group.s_addr;
imo.imo_multicast_ifp = inm->inm_ifp;
imo.imo_multicast_ttl = 1;
imo.imo_multicast_vif = -1;
/*
* Request loopback of the report if we are acting as a multicast
* router, so that the process-level routing daemon can hear it.
*/
imo.imo_multicast_loop = (ip_mrouter != NULL);
/*
* XXX
* Do we have to worry about reentrancy here? Don't think so.
*/
ip_output(m, router_alert, &igmprt, 0, &imo, NULL);
++igmpstat.igps_snd_reports;
}