util.dns: Library for decoding DNS records

Imported from luaunbound-prosody 5f7c771138b1

1 files changed, 271 insertions, 0 deletions

diff --git a/util/dns.lua b/util/dns.lua
new file mode 100644
index 00000000..2a15fbc4
--- /dev/null
+++ b/util/dns.lua
@@ -0,0 +1,271 @@
+-- libunbound based net.adns replacement for Prosody IM
+-- Copyright (C) 2012-2015 Kim Alvefur
+-- Copyright (C) 2012 Waqas Hussain
+--
+-- This file is MIT licensed.
+
+local setmetatable = setmetatable;
+local table = table;
+local t_concat = table.concat;
+local t_insert = table.insert;
+local s_byte = string.byte;
+local s_char = string.char;
+local s_format = string.format;
+local s_gsub = string.gsub;
+local s_sub = string.sub;
+local s_match = string.match;
+local s_gmatch = string.gmatch;
+
+local have_net, net_util = pcall(require, "util.net");
+
+if have_net and not net_util.ntop then -- Added in Prosody 0.11
+	have_net = false;
+end
+
+local chartohex = {};
+
+for c = 0, 255 do
+	chartohex[s_char(c)] = s_format("%02X", c);
+end
+
+local function tohex(s)
+	return (s_gsub(s, ".", chartohex));
+end
+
+-- Converted from
+-- http://www.iana.org/assignments/dns-parameters
+-- 2015-05-19
+
+local classes = {
+	IN = 1; "IN";
+	nil;
+	CH = 3; "CH";
+	HS = 4; "HS";
+};
+
+local types = {
+"A";"NS";"MD";"MF";"CNAME";"SOA";"MB";"MG";"MR";"NULL";"WKS";"PTR";"HINFO";
+"MINFO";"MX";"TXT";"RP";"AFSDB";"X25";"ISDN";"RT";"NSAP";"NSAP-PTR";"SIG";
+"KEY";"PX";"GPOS";"AAAA";"LOC";"NXT";"EID";"NIMLOC";"SRV";"ATMA";"NAPTR";
+"KX";"CERT";"A6";"DNAME";"SINK";"OPT";"APL";"DS";"SSHFP";"IPSECKEY";"RRSIG";
+"NSEC";"DNSKEY";"DHCID";"NSEC3";"NSEC3PARAM";"TLSA";[55]="HIP";[56]="NINFO";
+[57]="RKEY";[58]="TALINK";[59]="CDS";[60]="CDNSKEY";[61]="OPENPGPKEY";
+[62]="CSYNC";TLSA=52;NS=2;[249]="TKEY";[251]="IXFR";NSAP=22;UID=101;APL=42;
+MG=8;NIMLOC=32;DHCID=49;TALINK=58;HINFO=13;MINFO=14;EID=31;DS=43;CSYNC=62;
+RKEY=57;TKEY=249;NID=104;NAPTR=35;RT=21;LP=107;L32=105;KEY=25;MD=3;MX=15;
+A6=38;KX=36;PX=26;CAA=257;WKS=11;TSIG=250;MAILA=254;CDS=59;SINK=40;LOC=29;
+DLV=32769;[32769]="DLV";TA=32768;[32768]="TA";GID=102;IXFR=251;MAILB=253;
+[256]="URI";[250]="TSIG";[252]="AXFR";NSEC=47;HIP=55;[254]="MAILA";[255]="*";
+NSEC3PARAM=51;["*"]=255;URI=256;[253]="MAILB";AXFR=252;SPF=99;NXT=30;AFSDB=18;
+EUI48=108;NINFO=56;CDNSKEY=60;ISDN=20;L64=106;SRV=33;DNSKEY=48;X25=19;TXT=16;
+RRSIG=46;OPENPGPKEY=61;DNAME=39;CNAME=5;EUI64=109;A=1;MR=9;IPSECKEY=45;OPT=41;
+UNSPEC=103;["NSAP-PTR"]=23;[103]="UNSPEC";[257]="CAA";UINFO=100;[99]="SPF";
+MF=4;[101]="UID";[102]="GID";SOA=6;[104]="NID";[105]="L32";[106]="L64";
+[107]="LP";[108]="EUI48";[109]="EUI64";NSEC3=50;RP=17;PTR=12;[100]="UINFO";
+NULL=10;AAAA=28;MB=7;GPOS=27;SSHFP=44;CERT=37;SIG=24;ATMA=34
+};
+
+local errors = {
+	NoError = "No Error"; [0] = "NoError";
+	FormErr = "Format Error"; "FormErr";
+	ServFail = "Server Failure"; "ServFail";
+	NXDomain = "Non-Existent Domain"; "NXDomain";
+	NotImp = "Not Implemented"; "NotImp";
+	Refused = "Query Refused"; "Refused";
+	YXDomain = "Name Exists when it should not"; "YXDomain";
+	YXRRSet = "RR Set Exists when it should not"; "YXRRSet";
+	NXRRSet = "RR Set that should exist does not"; "NXRRSet";
+	NotAuth = "Server Not Authoritative for zone"; "NotAuth";
+	NotZone = "Name not contained in zone"; "NotZone";
+};
+
+-- Simplified versions of Waqas DNS parsers
+-- Only the per RR parsers are needed and only feed a single RR
+
+local parsers = {};
+
+-- No support for pointers, but libunbound appears to take care of that.
+local function readDnsName(packet, pos)
+	if s_byte(packet, pos) == 0 then return "."; end
+	local pack_len, r, len = #packet, {};
+	pos = pos or 1;
+	repeat
+		len = s_byte(packet, pos) or 0;
+		t_insert(r, s_sub(packet, pos + 1, pos + len));
+		pos = pos + len + 1;
+	until len == 0 or pos >= pack_len;
+	return t_concat(r, "."), pos;
+end
+
+-- These are just simple names.
+parsers.CNAME = readDnsName;
+parsers.NS = readDnsName
+parsers.PTR = readDnsName;
+
+local soa_mt = {
+	__tostring = function(rr)
+		return s_format("%s %s %d %d %d %d %d", rr.mname, rr.rname, rr.serial, rr.refresh, rr.retry, rr.expire, rr.minimum);
+	end;
+};
+function parsers.SOA(packet)
+	local mname, rname, offset;
+
+	mname, offset = readDnsName(packet, 1);
+	rname, offset = readDnsName(packet, offset);
+
+	-- Extract all the bytes of these fields in one call
+	local
+		s1, s2, s3, s4, -- serial
+		r1, r2, r3, r4, -- refresh
+		t1, t2, t3, t4, -- retry
+		e1, e2, e3, e4, -- expire
+		m1, m2, m3, m4  -- minimum
+			= s_byte(packet, offset, offset + 19);
+
+	return setmetatable({
+		mname = mname;
+		rname = rname;
+		serial  = s1*0x1000000 + s2*0x10000 + s3*0x100 + s4;
+		refresh = r1*0x1000000 + r2*0x10000 + r3*0x100 + r4;
+		retry   = t1*0x1000000 + t2*0x10000 + t3*0x100 + t4;
+		expire  = e1*0x1000000 + e2*0x10000 + e3*0x100 + e4;
+		minimum = m1*0x1000000 + m2*0x10000 + m3*0x100 + m4;
+	}, soa_mt);
+end
+
+function parsers.A(packet)
+	return s_format("%d.%d.%d.%d", s_byte(packet, 1, 4));
+end
+
+local aaaa = { nil, nil, nil, nil, nil, nil, nil, nil, };
+function parsers.AAAA(packet)
+	local hi, lo, ip, len, token;
+	for i = 1, 8 do
+		hi, lo = s_byte(packet, i * 2 - 1, i * 2);
+		aaaa[i] = s_format("%x", hi * 256 + lo); -- skips leading zeros
+	end
+	ip = t_concat(aaaa, ":", 1, 8);
+	len = (s_match(ip, "^0:[0:]+()") or 1) - 1;
+	for s in s_gmatch(ip, ":0:[0:]+") do
+		if len < #s then len, token = #s, s; end -- find longest sequence of zeros
+	end
+	return (s_gsub(ip, token or "^0:[0:]+", "::", 1));
+end
+
+if have_net then
+	parsers.A = net_util.ntop;
+	parsers.AAAA = net_util.ntop;
+end
+
+local mx_mt = {
+	__tostring = function(rr)
+		return s_format("%d %s", rr.pref, rr.mx)
+	end
+};
+function parsers.MX(packet)
+	local name = readDnsName(packet, 3);
+	local b1,b2 = s_byte(packet, 1, 2);
+	return setmetatable({
+		pref = b1*256+b2;
+		mx = name;
+	}, mx_mt);
+end
+
+local srv_mt = {
+	__tostring = function(rr)
+		return s_format("%d %d %d %s", rr.priority, rr.weight, rr.port, rr.target);
+	end
+};
+function parsers.SRV(packet)
+	local name = readDnsName(packet, 7);
+	local b1, b2, b3, b4, b5, b6 = s_byte(packet, 1, 6);
+	return setmetatable({
+		priority = b1*256+b2;
+		weight   = b3*256+b4;
+		port     = b5*256+b6;
+		target   = name;
+	}, srv_mt);
+end
+
+local txt_mt = { __tostring = t_concat };
+function parsers.TXT(packet)
+	local pack_len = #packet;
+	local r, pos, len = {}, 1;
+	repeat
+		len = s_byte(packet, pos) or 0;
+		t_insert(r, s_sub(packet, pos + 1, pos + len));
+		pos = pos + len + 1;
+	until pos >= pack_len;
+	return setmetatable(r, txt_mt);
+end
+
+parsers.SPF = parsers.TXT;
+
+-- Acronyms from RFC 7218
+local tlsa_usages = {
+	[0] = "PKIX-CA";
+	[1] = "PKIX-EE";
+	[2] = "DANE-TA";
+	[3] = "DANE-EE";
+	[255] = "PrivCert";
+};
+local tlsa_selectors = {
+	[0] = "Cert",
+	[1] = "SPKI",
+	[255] = "PrivSel",
+};
+local tlsa_match_types = {
+	[0] = "Full",
+	[1] = "SHA2-256",
+	[2] = "SHA2-512",
+	[255] = "PrivMatch",
+};
+local tlsa_mt = {
+	__tostring = function(rr)
+		return s_format("%s %s %s %s",
+			tlsa_usages[rr.use] or rr.use,
+			tlsa_selectors[rr.select] or rr.select,
+			tlsa_match_types[rr.match] or rr.match,
+			tohex(rr.data));
+	end;
+	__index = {
+		getUsage = function(rr) return tlsa_usages[rr.use] end;
+		getSelector = function(rr) return tlsa_selectors[rr.select] end;
+		getMatchType = function(rr) return tlsa_match_types[rr.match] end;
+	}
+};
+function parsers.TLSA(packet)
+	local use, select, match = s_byte(packet, 1,3);
+	return setmetatable({
+		use = use;
+		select = select;
+		match = match;
+		data = s_sub(packet, 4);
+	}, tlsa_mt);
+end
+
+local params = {
+	TLSA = {
+		use = tlsa_usages;
+		select = tlsa_selectors;
+		match = tlsa_match_types;
+	};
+};
+
+local fallback_mt = {
+	__tostring = function(rr)
+		return s_format([[\# %d %s]], #rr.raw, tohex(rr.raw));
+	end;
+};
+local function fallback_parser(packet)
+	return setmetatable({ raw = packet },fallback_mt);
+end
+setmetatable(parsers, { __index = function() return fallback_parser end });
+
+return {
+	parsers = parsers;
+	classes = classes;
+	types = types;
+	errors = errors;
+	params = params;
+};