On Nov 28, 2011, at 7:18 PM, Bart Van Assche wrote: On Mon, Nov 28, 2011 at 4:39 PM, Nikolay Denev <[email protected]> wrote:
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.
Please start from the trunk when preparing patches, otherwise you might miss commit 85f893e2b605e67f9bd0443c74e2ed269aa68564.
Bart.
Ok, here it is a patch against trunk that restores IP_RECVDSTADDR on FreeBSD (I have no other *BSD machine to test):
(Also attached).
Regards, Nikolay
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net-snmp-trunk-ip_recvdstaddr.patch
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