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util/dns.lua @ 13029:8ad432953300
mod_debug_reset: Remove now unused import of util.time (thanks luacheck)
author | Matthew Wild <mwild1@gmail.com> |
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date | Thu, 06 Apr 2023 14:49:11 +0100 |
parent | 12975:d10957394a3c |
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-- 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 "prosody.util.dnsregistry"; local tohex = require "prosody.util.hex".encode; local inet_ntop = require "prosody.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; };