Fix a regression where DVMRP diagnostic traffic, such as that used
by mrinfo and mtrace, was dropped by the IGMP TTL check. IGMP control traffic must always have a TTL of 1. Submitted by: Matthew Luckie MFC after: 3 days
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8bac98182a
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fd963b9929
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=207275
@ -1468,12 +1468,6 @@ igmp_input(struct mbuf *m, int off)
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}
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ip = mtod(m, struct ip *);
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if (ip->ip_ttl != 1) {
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IGMPSTAT_INC(igps_rcv_badttl);
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m_freem(m);
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return;
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}
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/*
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* Validate checksum.
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*/
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@ -1488,6 +1482,17 @@ igmp_input(struct mbuf *m, int off)
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m->m_data -= iphlen;
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m->m_len += iphlen;
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/*
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* IGMP control traffic is link-scope, and must have a TTL of 1.
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* DVMRP traffic (e.g. mrinfo, mtrace) is an exception;
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* probe packets may come from beyond the LAN.
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*/
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if (igmp->igmp_type != IGMP_DVMRP && ip->ip_ttl != 1) {
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IGMPSTAT_INC(igps_rcv_badttl);
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m_freem(m);
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return;
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}
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switch (igmp->igmp_type) {
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case IGMP_HOST_MEMBERSHIP_QUERY:
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if (igmplen == IGMP_MINLEN) {
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