Bug #44885 for Net-DNS: bug(?): Net::DNS returns empty string instead of "." for root

>> Wed Apr 08 19:59:17 2009: Request 44885 was acted upon. >> Transaction: Ticket created by dlamacchia@cloudmark.com >> Queue: Net-DNS >> Subject: bug(?): Net::DNS returns empty string instead of "." >> for root >> Broken in: (no value) >> Severity: (no value) >> Owner: Nobody >> Requestors: dlamacchia@cloudmark.com >> Status: new >> Ticket <URL: http://rt.cpan.org/Ticket/Display.html?id=44885 > >> >> >> Hi there, >> >> According to RFC 2181, "The zero length full name is defined as >> representing the root of the DNS tree, and is typically written and >> displayed as "." ." I've found that Net::DNS (latest, 0.65) returns >> "" (empty string) instead of "." for these domains, whereas dig/host/ >> nslookup/etc. return "." I work for an anti-spam company and we've >> found a lot of spammy IPs that exhibit this issue. >> >> You may disagree that this needs to be fixed -- the RFC says that the >> root is *typically* written but this is not a requirement that MUST >> be >> followed. However, due to the disagreement with dig/host/nslookup/ >> etc >> I'm submitting the issue. >> >> Basic information: >> >> Distribution name and version: Net-DNS-0.65 (latest) >> Perl version: perl v5.8.8 (i486-linux-gnu-thread-multi) >> Operating System vendor and version: Linux freeside 2.6.24-22-generic >> #1 SMP Mon Nov 24 18:32:42 UTC 2008 i686 GNU/Linux (this is Ubuntu, >> hardy heron). >> >> Sample data: >> >> Here's an IP and the output from dig: >> >> % dig -x 74.63.95.254 >> >> ; <<>> DiG 9.4.2-P2 <<>> -x 74.63.95.254 >> ;; global options: printcmd >> ;; Got answer: >> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 20464 >> ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 >> >> ;; QUESTION SECTION: >> ;254.95.63.74.in-addr.arpa. IN PTR >> >> ;; ANSWER SECTION: >> 254.95.63.74.in-addr.arpa. 10186 IN PTR . >> >> ;; Query time: 3 msec >> ;; SERVER: 172.20.0.21#53(172.20.0.21) >> ;; WHEN: Wed Apr 8 16:32:22 2009 >> ;; MSG SIZE rcvd: 56 >> >> (note the '.' above) >> >> I ran wireshark an looked at the answer packet data: >> >> Domain Name System (response) >> [Request In: 714] >> [Time: 0.000556000 seconds] >> Transaction ID: 0xcfa1 >> Flags: 0x8180 (Standard query response, No error) >> Questions: 1 >> Answer RRs: 1 >> Authority RRs: 0 >> Additional RRs: 0 >> Queries >> 254.95.63.74.in-addr.arpa: type PTR, class IN >> Name: 254.95.63.74.in-addr.arpa >> Type: PTR (Domain name pointer) >> Class: IN (0x0001) >> Answers >> 254.95.63.74.in-addr.arpa: type PTR, class IN, <Root> >> Name: 254.95.63.74.in-addr.arpa >> Type: PTR (Domain name pointer) >> Class: IN (0x0001) >> Time to live: 2 hours, 36 minutes, 24 seconds >> Data length: 1 >> Domain name: <Root> >> >> 0000 00 0f fe 89 c0 8b 00 11 20 d1 8d c6 08 00 45 >> 00 ........ .....E. >> 0010 00 54 5a cd 00 00 7f 11 86 0e ac 14 00 15 ac >> 14 .TZ............. >> 0020 02 80 00 35 a5 3f 00 40 c3 13 cf a1 81 80 00 01 ... >> 5.?.@........ >> 0030 00 01 00 00 00 00 03 32 35 34 02 39 35 02 36 33 ....... >> 254.95.63 >> 0040 02 37 34 07 69 6e 2d 61 64 64 72 04 61 72 70 61 .74.in- >> addr.arpa >> 0050 00 00 0c 00 01 c0 0c 00 0c 00 01 00 00 24 a8 00 ............. >> $.. >> 0060 01 00 >> >> Those last two bytes are the answer length (01) and the data (00). >> >> I made a patch for both netdns.c (netdns_dn_expand) and Packet.pm >> (dn_expand_PP). I'm not claiming the patch is perfect, but it should >> at least be a start. I've attached the patches. >> >> Thanks! >> >> -dave >> >> >> >> >> Hi there, >> >> According to RFC 2181, "The zero length full name is defined as >> representing the root of the DNS tree, and is typically written and >> displayed as "." ." I've found that Net::DNS (latest, 0.65) returns >> "" (empty string) instead of "." for these domains, whereas dig/host/ >> nslookup/etc. return "." I work for an anti-spam company and we've >> found a lot of spammy IPs that exhibit this issue. >> >> You may disagree that this needs to be fixed -- the RFC says that >> the root is *typically* written but this is not a requirement that >> MUST be followed. However, due to the disagreement with dig/host/ >> nslookup/etc I'm submitting the issue. >> >> Basic information: >> >> Distribution name and version: Net-DNS-0.65 (latest) >> Perl version: perl v5.8.8 (i486-linux-gnu-thread-multi) >> Operating System vendor and version: Linux freeside 2.6.24-22- >> generic #1 SMP Mon Nov 24 18:32:42 UTC 2008 i686 GNU/Linux (this is >> Ubuntu, hardy heron). >> >> Sample data: >> >> Here's an IP and the output from dig: >> >> % dig -x 74.63.95.254 >> >> ; <<>> DiG 9.4.2-P2 <<>> -x 74.63.95.254 >> ;; global options: printcmd >> ;; Got answer: >> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 20464 >> ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 >> >> ;; QUESTION SECTION: >> ;254.95.63.74.in-addr.arpa. IN PTR >> >> ;; ANSWER SECTION: >> 254.95.63.74.in-addr.arpa. 10186 IN PTR . >> >> ;; Query time: 3 msec >> ;; SERVER: 172.20.0.21#53(172.20.0.21) >> ;; WHEN: Wed Apr 8 16:32:22 2009 >> ;; MSG SIZE rcvd: 56 >> >> (note the '.' above) >> >> I ran wireshark an looked at the answer packet data: >> >> Domain Name System (response) >> [Request In: 714] >> [Time: 0.000556000 seconds] >> Transaction ID: 0xcfa1 >> Flags: 0x8180 (Standard query response, No error) >> Questions: 1 >> Answer RRs: 1 >> Authority RRs: 0 >> Additional RRs: 0 >> Queries >> 254.95.63.74.in-addr.arpa: type PTR, class IN >> Name: 254.95.63.74.in-addr.arpa >> Type: PTR (Domain name pointer) >> Class: IN (0x0001) >> Answers >> 254.95.63.74.in-addr.arpa: type PTR, class IN, <Root> >> Name: 254.95.63.74.in-addr.arpa >> Type: PTR (Domain name pointer) >> Class: IN (0x0001) >> Time to live: 2 hours, 36 minutes, 24 seconds >> Data length: 1 >> Domain name: <Root> >> >> 0000 00 0f fe 89 c0 8b 00 11 20 d1 8d c6 08 00 45 >> 00 ........ .....E. >> 0010 00 54 5a cd 00 00 7f 11 86 0e ac 14 00 15 ac >> 14 .TZ............. >> 0020 02 80 00 35 a5 3f 00 40 c3 13 cf a1 81 80 00 01 ... >> 5.?.@........ >> 0030 00 01 00 00 00 00 03 32 35 34 02 39 35 02 36 33 ....... >> 254.95.63 >> 0040 02 37 34 07 69 6e 2d 61 64 64 72 04 61 72 70 61 .74.in- >> addr.arpa >> 0050 00 00 0c 00 01 c0 0c 00 0c 00 01 00 00 24 a8 00 ............. >> $.. >> 0060 01 00 >> >> Those last two bytes are the answer length (01) and the data (00). >> >> I made a patch for both netdns.c (netdns_dn_expand) and Packet.pm >> (dn_expand_PP). I'm not claiming the patch is perfect, but it >> should at least be a start. I've attached the patches. >> >> Thanks! >> >> -dave >> <netdns.c.patch> >> <Packet.pm.patch> >> >> >>