Hello coders,
Some time ago I submitted patch that added support for IP_RECVDSTADDR on *BSDs,
as the code
was only using IP_PKTINFO on Linux for the same behavior i.e.: when querying
multi homed host via udp snmp
the host should reply from the IP address that the query was sent to, else many
statefull firewalls get confused and drop the packets.
The original patch is here :
http://sourceforge.net/tracker/?func=detail&aid=3175640&group_id=12694&atid=312694
I've never actually had the chance to test the modified patch that was
committed to the source before, as I was running my patched version,
but recently I've upgraded some of my net-snmp daemons and it turned out that
the IP_RECVDSTADDR support is broken on several places.
I'll try to work on this in the next few days, but from first glance there are
several things missing . i.e.:
On line 119 in snmplib/transports/snmpUDPBaseDomain.c:netsnmp_udpbase_recv
#if defined(linux) && defined(IP_PKTINFO)
socklen_t local_addr_len = sizeof(addr_pair->local_addr);
rc = netsnmp_udp_recvfrom(t->sock, buf, size, from, &fromlen,
(struct
sockaddr*)&(addr_pair->local_addr),
&local_addr_len,
&(addr_pair->if_index));
#else
rc = recvfrom(t->sock, buf, size, NETSNMP_DONTWAIT, from,
&fromlen);
#endif /* linux && IP_PKTINFO */
Here the "if" should actually be :
#if (defined(linux) && defined(IP_PKTINFO)) || defined(IP_RECVDSTADDR)
The same error can be seen on line 176 in
snmplib/transports/snmpUDPBaseDomain.c:netsnmp_udpbase_send
I.e. even if we have defined the functions that use IP_RECVDSTADDR they are
never used.
Also the setsockopt() that sets IP_RECVDSTADDR is missing.
I'll try to come up with a patch so this can be fixed.
Regards,
Nikolay
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