Library dns
Simple DNS library supporting packet creation, encoding, decoding, and querying.
Copyright© Same as Nmap--See http://nmap.org/book/man-legal.html
Source: http://nmap.org/svn/nselib/dns.lua
Functions
| additionalFetcher[types.A] (dec, retAll) |
Additional fetcher for A records |
| additionalFetcher[types.AAAA] (dec, retAll) |
Additional fetcher for AAAA records. |
| additionalFetcher[types.TXT] (dec, retAll) |
Additional fetcher for TXT records. |
| addQuestion (pkt, dname, dtype) |
Adds a question to a DNS packet table. |
| answerFetcher[types.A] (dec, retAll) |
Answer fetcher for A records |
| answerFetcher[types.AAAA] (dec, retAll) |
Answer fetcher for AAAA records. |
| answerFetcher[types.CNAME] (dec, retAll) |
Answer fetcher for CNAME records. |
| answerFetcher[types.NS] (dec) |
Answer fetcher for NS records. |
| answerFetcher[types.PTR] (dec, retAll) |
Answer fetcher for PTR records. |
| answerFetcher[types.TXT] (dec, retAll) |
Answer fetcher for TXT records. |
| decDomain (entry, data, pos) |
Decodes records that consist only of one domain, for example CNAME, NS, PTR.
Puts result in |
| decode (data) |
Decodes a DNS packet. |
| decodeFlags (flgStr) |
Decodes DNS flags. |
| decodeQuestions (data, count, pos) |
Decodes questions in a DNS packet. |
| decoder[types.A] (entry) |
Decodes IP of A record, puts it in |
| decoder[types.AAAA] (entry) |
Decodes IP of AAAA record, puts it in |
| decoder[types.CNAME] (entry, data, pos) |
Decodes CNAME records.
Puts result in |
| decoder[types.NS] (entry, data, pos) |
Decodes NS records.
Puts result in |
| decoder[types.PTR] (entry, data, pos) |
Decodes PTR records.
Puts result in |
| decoder[types.SOA] (entry, data, pos) |
Decodes SOA record, puts it in |
| decoder[types.SSHFP] (entry) |
Decodes SSH fingerprint record, puts it in |
| decoder[types.TXT] (entry, data, pos) |
Decodes TXT records.
Puts result in |
| decodeRR (data, count, pos) |
Decodes returned resource records (answer, authority, or additional part). |
| decStr (data, pos) |
Decodes a domain in a DNS packet. Handles "compressed" data too. |
| encode (pkt) |
Encode a DNS packet. |
| encodeFlags (flags) |
Encodes DNS flags to a binary digit string. |
| encodeQuestions (questions) |
Encodes the question part of a DNS request. |
| findNiceAdditional (dtype, dec, retAll) |
Calls the answer fetcher for |
| findNiceAnswer (dtype, dec, retAll) |
Calls the answer fetcher for |
| getAuthDns (rPkt) |
Tries to find the next nameserver with authority to get a result for query. |
| gotAnswer (rPkt) |
Checks if a DNS response packet contains a useful answer. |
| newPacket () |
Creates a new table representing a DNS packet. |
| query (dname, options) |
Query DNS servers for a DNS record. |
| reverse (ip) |
Formats an IP address for reverse lookup. |
| sendPackets (data, host, port, timeout, cnt) |
Repeatedly sends UDP packets to host, waiting for an answer. |
| str2tbl (str) |
Splits a string up into a table of single characters. |
Tables
| types |
Table of DNS resource types. |
Functions
- additionalFetcher[types.A] (dec, retAll)
-
Additional fetcher for A records
Parameters
- dec: Decoded DNS response.
- retAll: If true, return all entries, not just the first.
Return values:
- True if one or more answers of the required type were found - otherwise false.
- String first dns A record or Table of A records or String Error message.
- additionalFetcher[types.AAAA] (dec, retAll)
-
Additional fetcher for AAAA records.
Parameters
- dec: Decoded DNS response.
- retAll: If true, return all entries, not just the first.
Return values:
- True if one or more answers of the required type were found - otherwise false.
- String first dns AAAA record or Table of AAAA records or String Error message.
- additionalFetcher[types.TXT] (dec, retAll)
-
Additional fetcher for TXT records.
Parameters
- dec: Decoded DNS response.
- retAll: If true, return all entries, not just the first.
Return values:
- True if one or more answers of the required type were found - otherwise false.
- String first dns TXT record or Table of TXT records or String Error message.
- addQuestion (pkt, dname, dtype)
-
Adds a question to a DNS packet table.
Parameters
- pkt: Table representing DNS packet.
- dname: Domain name to be asked.
- dtype: RR to be asked.
- answerFetcher[types.A] (dec, retAll)
-
Answer fetcher for A records
Parameters
- dec: Decoded DNS response.
- retAll: If true, return all entries, not just the first.
Return values:
- True if one or more answers of the required type were found - otherwise false.
- String first dns A record or Table of A records or String Error message.
- answerFetcher[types.AAAA] (dec, retAll)
-
Answer fetcher for AAAA records.
Parameters
- dec: Decoded DNS response.
- retAll: If true, return all entries, not just the first.
Return values:
- True if one or more answers of the required type were found - otherwise false.
- String first dns AAAA record or Table of AAAA records or String Error message.
- answerFetcher[types.CNAME] (dec, retAll)
-
Answer fetcher for CNAME records.
Parameters
- dec: Decoded DNS response.
- retAll: If true, return all entries, not just the first.
Return values:
- True if one or more answers of the required type were found - otherwise false.
- String first Domain entry or Table of domain entries or String Error message.
- answerFetcher[types.NS] (dec)
-
Answer fetcher for NS records.
Parameters
- dec: Decoded DNS response.
Return values:
- True if one or more answers of the required type were found - otherwise false.
- String first Domain entry or Table of domain entries or String Error message.
- answerFetcher[types.PTR] (dec, retAll)
-
Answer fetcher for PTR records.
Parameters
- dec: Decoded DNS response.
- retAll: If true, return all entries, not just the first.
Return values:
- True if one or more answers of the required type were found - otherwise false.
- String first Domain entry or Table of domain entries or String Error message.
- answerFetcher[types.TXT] (dec, retAll)
-
Answer fetcher for TXT records.
Parameters
- dec: Decoded DNS response.
- retAll: If true, return all entries, not just the first.
Return values:
- True if one or more answers of the required type were found - otherwise false.
- String first dns TXT record or Table of TXT records or String Error message.
- decDomain (entry, data, pos)
-
Decodes records that consist only of one domain, for example CNAME, NS, PTR. Puts result in
entry.domain.Parameters
- entry: RR in packet.
- data: Complete encoded DNS packet.
- pos: Position in packet after RR.
- decode (data)
-
Decodes a DNS packet.
Parameters
- data: Encoded DNS packet.
Return value:
Table representing DNS packet. - decodeFlags (flgStr)
-
Decodes DNS flags.
Parameters
- flgStr: Flags as a binary digit string.
Return value:
Table representing flags. - decodeQuestions (data, count, pos)
-
Decodes questions in a DNS packet.
Parameters
- data: Complete DNS packet.
- count: Value of question counter in header.
- pos: Starting position in packet.
Return values:
- Position after decoding.
- Table of decoded questions.
- decoder[types.A] (entry)
-
Decodes IP of A record, puts it in
entry.ip.Parameters
- entry: RR in packet.
- decoder[types.AAAA] (entry)
-
Decodes IP of AAAA record, puts it in
entry.ipv6.Parameters
- entry: RR in packet.
- decoder[types.CNAME] (entry, data, pos)
-
Decodes CNAME records. Puts result in
entry.domain.Parameters
- entry: RR in packet.
- data: Complete encoded DNS packet.
- pos: Position in packet after RR.
- decoder[types.NS] (entry, data, pos)
-
Decodes NS records. Puts result in
entry.domain.Parameters
- entry: RR in packet.
- data: Complete encoded DNS packet.
- pos: Position in packet after RR.
- decoder[types.PTR] (entry, data, pos)
-
Decodes PTR records. Puts result in
entry.domain.Parameters
- entry: RR in packet.
- data: Complete encoded DNS packet.
- pos: Position in packet after RR.
- decoder[types.SOA] (entry, data, pos)
-
Decodes SOA record, puts it in
entry.SOA.entry.SOAhas the fieldsmname,rname,serial,refresh,retry,expire, andminimum.Parameters
- entry: RR in packet.
- data: Complete encoded DNS packet.
- pos: Position in packet after RR.
- decoder[types.SSHFP] (entry)
-
Decodes SSH fingerprint record, puts it in
entry.SSHFPas defined in RFC 4255.entry.SSHFPhas the fieldsalgorithm,fptype, andfingerprint.Parameters
- entry: RR in packet.
- decoder[types.TXT] (entry, data, pos)
-
Decodes TXT records. Puts result in
entry.domain.Parameters
- entry: RR in packet.
- data: Complete encoded DNS packet.
- pos: Position in packet after RR.
- decodeRR (data, count, pos)
-
Decodes returned resource records (answer, authority, or additional part).
Parameters
- data: Complete encoded DNS packet.
- count: Value of according counter in header.
- pos: Starting position in packet.
Return value:
Table of RRs. - decStr (data, pos)
-
Decodes a domain in a DNS packet. Handles "compressed" data too.
Parameters
- data: Complete DNS packet.
- pos: Starting position in packet.
Return values:
- Position after decoding.
- Decoded domain, or
nilon error.
- encode (pkt)
-
Encode a DNS packet.
Caution: doesn't encode answer, authority and additional part.
Parameters
-
pkt:
Table representing DNS packet, initialized by
newPacket.
Return value:
Encoded DNS packet. -
pkt:
Table representing DNS packet, initialized by
- encodeFlags (flags)
-
Encodes DNS flags to a binary digit string.
Parameters
- flags: Flag table, each entry representing a flag (QR, OCx, AA, TC, RD, RA, RCx).
Return value:
Binary digit string representing flags. - encodeQuestions (questions)
-
Encodes the question part of a DNS request.
Parameters
- questions: Table of questions.
Return value:
Encoded question string. - findNiceAdditional (dtype, dec, retAll)
-
Calls the answer fetcher for
dtypeor returns an error code in case of a "no such name" error.Parameters
- dtype: DNS resource record type.
- dec: Decoded DNS response.
- retAll: If true, return all entries, not just the first.
Return values:
- True if one or more answers of the required type were found - otherwise false.
- Answer according to the answer fetcher for
dtypeor an Error message.
- findNiceAnswer (dtype, dec, retAll)
-
Calls the answer fetcher for
dtypeor returns an error code in case of a "no such name" error.Parameters
- dtype: DNS resource record type.
- dec: Decoded DNS response.
- retAll: If true, return all entries, not just the first.
Return values:
- True if one or more answers of the required type were found - otherwise false.
- Answer according to the answer fetcher for
dtypeor an Error message.
- getAuthDns (rPkt)
-
Tries to find the next nameserver with authority to get a result for query.
Parameters
- rPkt: Decoded DNS response packet
Return value:
String or table of next server(s) to query, or false. - gotAnswer (rPkt)
-
Checks if a DNS response packet contains a useful answer.
Parameters
- rPkt: Decoded DNS response packet.
Return value:
True if useful, false if not. - newPacket ()
-
Creates a new table representing a DNS packet.
Return value:
Table representing a DNS packet. - query (dname, options)
-
Query DNS servers for a DNS record.
Parameters
- dname: Desired domain name entry.
-
options:
A table containing any of the following fields:
dtype: Desired DNS record type (default:"A").host: DNS server to be queried (default: DNS servers known to Nmap).port: Port of DNS server to connect to (default:53).tries: How often shouldquerytry to contact another server (for non-recursive queries).retAll: Return all answers, not just the first.retPkt: Return the packet instead of using the answer-fetching mechanism.norecurseIf true, do not set the recursion (RD) flag.
Return values:
- True if a dns response was received and contained an answer of the requested type, or the decoded dns response was requested (retPkt) and is being returned - or False otherwise.
- String answer of the requested type, Table of answers or a String error message of one of the following: "No Such Name", "No Servers", "No Answers", "Unable to handle response"
- reverse (ip)
-
Formats an IP address for reverse lookup.
Parameters
- ip: IP address string.
Return value:
"Domain"-style representation of IP as subdomain of in-addr.arpa or ip6.arpa. - sendPackets (data, host, port, timeout, cnt)
-
Repeatedly sends UDP packets to host, waiting for an answer.
Parameters
- data: Data to be sent.
- host: Host to connect to.
- port: Port to connect to.
- timeout: Number of ms to wait for a response.
- cnt: Number of tries.
Return values:
- Status (true or false).
- Response (if status is true).
- str2tbl (str)
-
Splits a string up into a table of single characters.
Parameters
- str: String to be split up.
Return value:
Table of characters.