diff options
Diffstat (limited to 'util/dns.lua')
| -rw-r--r-- | util/dns.lua | 242 |
1 files changed, 242 insertions, 0 deletions
diff --git a/util/dns.lua b/util/dns.lua new file mode 100644 index 00000000..3b58e03e --- /dev/null +++ b/util/dns.lua @@ -0,0 +1,242 @@ +-- 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_format = string.format; +local s_sub = string.sub; + +local iana_data = require "util.dnsregistry"; +local tohex = require "util.hex".encode; +local inet_ntop = require "util.net".ntop; + +-- 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 ".", pos+1; 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 + +parsers.A = inet_ntop; +parsers.AAAA = inet_ntop; + +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 svcb_params = {"alpn"; "no-default-alpn"; "port"; "ipv4hint"; "ech"; "ipv6hint"}; +setmetatable(svcb_params, {__index = function(_, n) return "key" .. tostring(n); end}); + +local svcb_mt = { + __tostring = function (rr) + local kv = {}; + for i = 1, #rr.fields do + t_insert(kv, s_format("%s=%q", svcb_params[rr.fields[i].key], tostring(rr.fields[i].value))); + -- FIXME the =value part may be omitted when the value is "empty" + end + return s_format("%d %s %s", rr.prio, rr.name, t_concat(kv, " ")); + end; +}; +local svbc_ip_mt = {__tostring = function(ip) return t_concat(ip, ", "); end} + +function parsers.SVCB(packet) + local prio_h, prio_l = packet:byte(1,2); + local prio = prio_h*256+prio_l; + local name, pos = readDnsName(packet, 3); + local fields = {}; + while #packet > pos do + local key_h, key_l = packet:byte(pos+0,pos+1); + local len_h, len_l = packet:byte(pos+2,pos+3); + local key = key_h*256+key_l; + local len = len_h*256+len_l; + local value = packet:sub(pos+4,pos+4-1+len) + if key == 1 then + value = setmetatable(parsers.TXT(value), svbc_ip_mt); + elseif key == 3 then + local port_h, port_l = value:byte(1,2); + local port = port_h*256+port_l; + value = port; + elseif key == 4 then + local ip = {}; + for i = 1, #value, 4 do + t_insert(ip, parsers.A(value:sub(i, i+3))); + end + value = setmetatable(ip, svbc_ip_mt); + elseif key == 6 then + local ip = {}; + for i = 1, #value, 16 do + t_insert(ip, parsers.AAAA(value:sub(i, i+15))); + end + value = setmetatable(ip, svbc_ip_mt); + end + t_insert(fields, { key = key, value = value, len = len }); + pos = pos+len+4; + end + return setmetatable({ + prio = prio, name = name, fields = fields, + }, svcb_mt); +end + +parsers.HTTPS = parsers.SVCB; + +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 = iana_data.classes; + types = iana_data.types; + errors = iana_data.errors; + params = params; +}; |