-- Prosody IM -- This file is included with Prosody IM. It has modifications, -- which are hereby placed in the public domain. -- todo: quick (default) header generation -- todo: nxdomain, error handling -- todo: cache results of encodeName -- reference: http://tools.ietf.org/html/rfc1035 -- reference: http://tools.ietf.org/html/rfc1876 (LOC) local socket = require "socket"; local have_timer, timer = pcall(require, "util.timer"); local new_ip = require "util.ip".new_ip; local have_util_net, util_net = pcall(require, "util.net"); local log = require "util.logger".init("dns"); local _, windows = pcall(require, "util.windows"); local is_windows = (_ and windows) or os.getenv("WINDIR"); local coroutine, io, math, string, table = coroutine, io, math, string, table; local ipairs, next, pairs, print, setmetatable, tostring, assert, error, select, type = ipairs, next, pairs, print, setmetatable, tostring, assert, error, select, type; local ztact = { -- public domain 20080404 lua@ztact.com get = function(parent, ...) local len = select('#', ...); for i=1,len do parent = parent[select(i, ...)]; if parent == nil then break; end end return parent; end; set = function(parent, ...) local len = select('#', ...); local key, value = select(len-1, ...); local cutpoint, cutkey; for i=1,len-2 do local key = select (i, ...) local child = parent[key] if value == nil then if child == nil then return; elseif next(child, next(child)) then cutpoint = nil; cutkey = nil; elseif cutpoint == nil then cutpoint = parent; cutkey = key; end elseif child == nil then child = {}; parent[key] = child; end parent = child end if value == nil and cutpoint then cutpoint[cutkey] = nil; else parent[key] = value; return value; end end; }; local get, set = ztact.get, ztact.set; local default_timeout = 5; local default_jitter = 1; local default_retry_jitter = 2; -------------------------------------------------- module dns local _ENV = nil; -- luacheck: std none local dns = {}; -- dns type & class codes ------------------------------ dns type & class codes local append = table.insert local function highbyte(i) -- - - - - - - - - - - - - - - - - - - highbyte return (i-(i%0x100))/0x100; end local function augment (t, prefix) -- - - - - - - - - - - - - - - - - augment local a = {}; for i,s in pairs(t) do a[i] = s; a[s] = s; a[string.lower(s)] = s; end setmetatable(a, { __index = function (_, i) if type(i) == "number" then return ("%s%d"):format(prefix, i); elseif type(i) == "string" then return i:upper(); end end; }) return a; end local function encode (t) -- - - - - - - - - - - - - - - - - - - - - encode local code = {}; for i,s in pairs(t) do local word = string.char(highbyte(i), i%0x100); code[i] = word; code[s] = word; code[string.lower(s)] = word; end return code; end dns.types = { [1] = "A", -- a host address,[RFC1035],, [2] = "NS", -- an authoritative name server,[RFC1035],, [3] = "MD", -- a mail destination (OBSOLETE - use MX),[RFC1035],, [4] = "MF", -- a mail forwarder (OBSOLETE - use MX),[RFC1035],, [5] = "CNAME", -- the canonical name for an alias,[RFC1035],, [6] = "SOA", -- marks the start of a zone of authority,[RFC1035],, [7] = "MB", -- a mailbox domain name (EXPERIMENTAL),[RFC1035],, [8] = "MG", -- a mail group member (EXPERIMENTAL),[RFC1035],, [9] = "MR", -- a mail rename domain name (EXPERIMENTAL),[RFC1035],, [10] = "NULL", -- a null RR (EXPERIMENTAL),[RFC1035],, [11] = "WKS", -- a well known service description,[RFC1035],, [12] = "PTR", -- a domain name pointer,[RFC1035],, [13] = "HINFO", -- host information,[RFC1035],, [14] = "MINFO", -- mailbox or mail list information,[RFC1035],, [15] = "MX", -- mail exchange,[RFC1035],, [16] = "TXT", -- text strings,[RFC1035],, [17] = "RP", -- for Responsible Person,[RFC1183],, [18] = "AFSDB", -- for AFS Data Base location,[RFC1183][RFC5864],, [19] = "X25", -- for X.25 PSDN address,[RFC1183],, [20] = "ISDN", -- for ISDN address,[RFC1183],, [21] = "RT", -- for Route Through,[RFC1183],, [22] = "NSAP", -- "for NSAP address, NSAP style A record",[RFC1706],, [23] = "NSAP-PTR", -- "for domain name pointer, NSAP style",[RFC1348][RFC1637][RFC1706],, [24] = "SIG", -- for security signature,[RFC4034][RFC3755][RFC2535][RFC2536][RFC2537][RFC2931][RFC3110][RFC3008],, [25] = "KEY", -- for security key,[RFC4034][RFC3755][RFC2535][RFC2536][RFC2537][RFC2539][RFC3008][RFC3110],, [26] = "PX", -- X.400 mail mapping information,[RFC2163],, [27] = "GPOS", -- Geographical Position,[RFC1712],, [28] = "AAAA", -- IP6 Address,[RFC3596],, [29] = "LOC", -- Location Information,[RFC1876],, [30] = "NXT", -- Next Domain (OBSOLETE),[RFC3755][RFC2535],, [31] = "EID", -- Endpoint Identifier,[Michael_Patton][http://ana-3.lcs.mit.edu/~jnc/nimrod/dns.txt],,1995-06 [32] = "NIMLOC", -- Nimrod Locator,[1][Michael_Patton][http://ana-3.lcs.mit.edu/~jnc/nimrod/dns.txt],,1995-06 [33] = "SRV", -- Server Selection,[1][RFC2782],, [34] = "ATMA", -- ATM Address,"[ ATM Forum Technical Committee, ""ATM Name System, V2.0"", Doc ID: AF-DANS-0152.000, July 2000. Available from and held in escrow by IANA.]",, [35] = "NAPTR", -- Naming Authority Pointer,[RFC2915][RFC2168][RFC3403],, [36] = "KX", -- Key Exchanger,[RFC2230],, [37] = "CERT", -- CERT,[RFC4398],, [38] = "A6", -- A6 (OBSOLETE - use AAAA),[RFC3226][RFC2874][RFC6563],, [39] = "DNAME", -- DNAME,[RFC6672],, [40] = "SINK", -- SINK,[Donald_E_Eastlake][http://tools.ietf.org/html/draft-eastlake-kitchen-sink],,1997-11 [41] = "OPT", -- OPT,[RFC6891][RFC3225],, [42] = "APL", -- APL,[RFC3123],, [43] = "DS", -- Delegation Signer,[RFC4034][RFC3658],, [44] = "SSHFP", -- SSH Key Fingerprint,[RFC4255],, [45] = "IPSECKEY", -- IPSECKEY,[RFC4025],, [46] = "RRSIG", -- RRSIG,[RFC4034][RFC3755],, [47] = "NSEC", -- NSEC,[RFC4034][RFC3755],, [48] = "DNSKEY", -- DNSKEY,[RFC4034][RFC3755],, [49] = "DHCID", -- DHCID,[RFC4701],, [50] = "NSEC3", -- NSEC3,[RFC5155],, [51] = "NSEC3PARAM", -- NSEC3PARAM,[RFC5155],, [52] = "TLSA", -- TLSA,[RFC6698],, [53] = "SMIMEA", -- S/MIME cert association,[RFC8162],SMIMEA/smimea-completed-template,2015-12-01 -- [54] = "Unassigned", -- ,,, [55] = "HIP", -- Host Identity Protocol,[RFC8005],, [56] = "NINFO", -- NINFO,[Jim_Reid],NINFO/ninfo-completed-template,2008-01-21 [57] = "RKEY", -- RKEY,[Jim_Reid],RKEY/rkey-completed-template,2008-01-21 [58] = "TALINK", -- Trust Anchor LINK,[Wouter_Wijngaards],TALINK/talink-completed-template,2010-02-17 [59] = "CDS", -- Child DS,[RFC7344],CDS/cds-completed-template,2011-06-06 [60] = "CDNSKEY", -- DNSKEY(s) the Child wants reflected in DS,[RFC7344],,2014-06-16 [61] = "OPENPGPKEY", -- OpenPGP Key,[RFC7929],OPENPGPKEY/openpgpkey-completed-template,2014-08-12 [62] = "CSYNC", -- Child-To-Parent Synchronization,[RFC7477],,2015-01-27 -- [63 .. 98] = "Unassigned", -- ,,, [99] = "SPF", -- ,[RFC7208],, [100] = "UINFO", -- ,[IANA-Reserved],, [101] = "UID", -- ,[IANA-Reserved],, [102] = "GID", -- ,[IANA-Reserved],, [103] = "UNSPEC", -- ,[IANA-Reserved],, [104] = "NID", -- ,[RFC6742],ILNP/nid-completed-template, [105] = "L32", -- ,[RFC6742],ILNP/l32-completed-template, [106] = "L64", -- ,[RFC6742],ILNP/l64-completed-template, [107] = "LP", -- ,[RFC6742],ILNP/lp-completed-template, [108] = "EUI48", -- an EUI-48 address,[RFC7043],EUI48/eui48-completed-template,2013-03-27 [109] = "EUI64", -- an EUI-64 address,[RFC7043],EUI64/eui64-completed-template,2013-03-27 -- [110 .. 248] = "Unassigned", -- ,,, [249] = "TKEY", -- Transaction Key,[RFC2930],, [250] = "TSIG", -- Transaction Signature,[RFC2845],, [251] = "IXFR", -- incremental transfer,[RFC1995],, [252] = "AXFR", -- transfer of an entire zone,[RFC1035][RFC5936],, [253] = "MAILB", -- "mailbox-related RRs (MB, MG or MR)",[RFC1035],, [254] = "MAILA", -- mail agent RRs (OBSOLETE - see MX),[RFC1035],, [255] = "*", -- A request for all records the server/cache has available,[RFC1035][RFC6895],, [256] = "URI", -- URI,[RFC7553],URI/uri-completed-template,2011-02-22 [257] = "CAA", -- Certification Authority Restriction,[RFC6844],CAA/caa-completed-template,2011-04-07 [258] = "AVC", -- Application Visibility and Control,[Wolfgang_Riedel],AVC/avc-completed-template,2016-02-26 [259] = "DOA", -- Digital Object Architecture,[draft-durand-doa-over-dns],DOA/doa-completed-template,2017-08-30 -- [260 .. 32767] = "Unassigned", -- ,,, [32768] = "TA", -- DNSSEC Trust Authorities,"[Sam_Weiler][http://cameo.library.cmu.edu/][ Deploying DNSSEC Without a Signed Root. Technical Report 1999-19, Information Networking Institute, Carnegie Mellon University, April 2004.]",,2005-12-13 [32769] = "DLV", -- DNSSEC Lookaside Validation,[RFC4431],, -- [32770 .. 65279] = "Unassigned", -- ,,, -- [65280 .. 65534] = "Private use", -- ,,, -- [65535] = "Reserved", -- ,,, } dns.classes = { 'IN', 'CS', 'CH', 'HS', [255] = '*' }; dns.type = augment (dns.types, "TYPE"); dns.class = augment (dns.classes, "CLASS"); dns.typecode = encode (dns.types); dns.classcode = encode (dns.classes); local function standardize(qname, qtype, qclass) -- - - - - - - standardize if string.byte(qname, -1) ~= 0x2E then qname = qname..'.'; end qname = string.lower(qname); return qname, dns.type[qtype or 'A'], dns.class[qclass or 'IN']; end local function prune(rrs, time, soft) -- - - - - - - - - - - - - - - prune time = time or socket.gettime(); for i,rr in ipairs(rrs) do if rr.tod then if rr.tod < time then rrs[rr[rr.type:lower()]] = nil; table.remove(rrs, i); return prune(rrs, time, soft); -- Re-iterate end elseif soft == 'soft' then -- What is this? I forget! assert(rr.ttl == 0); rrs[rr[rr.type:lower()]] = nil; table.remove(rrs, i); end end end -- metatables & co. ------------------------------------------ metatables & co. local resolver = {}; resolver.__index = resolver; resolver.timeout = default_timeout; local function default_rr_tostring(rr) local rr_val = rr.type and rr[rr.type:lower()]; if type(rr_val) ~= "string" then return ""; end return rr_val; end local special_tostrings = { LOC = resolver.LOC_tostring; MX = function (rr) return string.format('%2i %s', rr.pref, rr.mx); end; SRV = function (rr) local s = rr.srv; return string.format('%5d %5d %5d %s', s.priority, s.weight, s.port, s.target); end; }; local rr_metatable = {}; -- - - - - - - - - - - - - - - - - - - rr_metatable function rr_metatable.__tostring(rr) local rr_string = (special_tostrings[rr.type] or default_rr_tostring)(rr); return string.format('%2s %-5s %6i %-28s %s', rr.class, rr.type, rr.ttl, rr.name, rr_string); end local rrs_metatable = {}; -- - - - - - - - - - - - - - - - - - rrs_metatable function rrs_metatable.__tostring(rrs) local t = {}; for _, rr in ipairs(rrs) do append(t, tostring(rr)..'\n'); end return table.concat(t); end local cache_metatable = {}; -- - - - - - - - - - - - - - - - cache_metatable function cache_metatable.__tostring(cache) local time = socket.gettime(); local t = {}; for class,types in pairs(cache) do for type,names in pairs(types) do for name,rrs in pairs(names) do prune(rrs, time); append(t, tostring(rrs)); end end end return table.concat(t); end -- packet layer -------------------------------------------------- packet layer function dns.random(...) -- - - - - - - - - - - - - - - - - - - dns.random math.randomseed(math.floor(10000*socket.gettime()) % 0x80000000); dns.random = math.random; return dns.random(...); end local function encodeHeader(o) -- - - - - - - - - - - - - - - encodeHeader o = o or {}; o.id = o.id or dns.random(0, 0xffff); -- 16b (random) id o.rd = o.rd or 1; -- 1b 1 recursion desired o.tc = o.tc or 0; -- 1b 1 truncated response o.aa = o.aa or 0; -- 1b 1 authoritative response o.opcode = o.opcode or 0; -- 4b 0 query -- 1 inverse query -- 2 server status request -- 3-15 reserved o.qr = o.qr or 0; -- 1b 0 query, 1 response o.rcode = o.rcode or 0; -- 4b 0 no error -- 1 format error -- 2 server failure -- 3 name error -- 4 not implemented -- 5 refused -- 6-15 reserved o.z = o.z or 0; -- 3b 0 reserved o.ra = o.ra or 0; -- 1b 1 recursion available o.qdcount = o.qdcount or 1; -- 16b number of question RRs o.ancount = o.ancount or 0; -- 16b number of answers RRs o.nscount = o.nscount or 0; -- 16b number of nameservers RRs o.arcount = o.arcount or 0; -- 16b number of additional RRs -- string.char() rounds, so prevent roundup with -0.4999 local header = string.char( highbyte(o.id), o.id %0x100, o.rd + 2*o.tc + 4*o.aa + 8*o.opcode + 128*o.qr, o.rcode + 16*o.z + 128*o.ra, highbyte(o.qdcount), o.qdcount %0x100, highbyte(o.ancount), o.ancount %0x100, highbyte(o.nscount), o.nscount %0x100, highbyte(o.arcount), o.arcount %0x100 ); return header, o.id; end local function encodeName(name) -- - - - - - - - - - - - - - - - encodeName local t = {}; for part in string.gmatch(name, '[^.]+') do append(t, string.char(string.len(part))); append(t, part); end append(t, string.char(0)); return table.concat(t); end local function encodeQuestion(qname, qtype, qclass) -- - - - encodeQuestion qname = encodeName(qname); qtype = dns.typecode[qtype or 'a']; qclass = dns.classcode[qclass or 'in']; return qname..qtype..qclass; end function resolver:byte(len) -- - - - - - - - - - - - - - - - - - - - - byte len = len or 1; local offset = self.offset; local last = offset + len - 1; if last > #self.packet then error(string.format('out of bounds: %i>%i', last, #self.packet)); end self.offset = offset + len; return string.byte(self.packet, offset, last); end function resolver:word() -- - - - - - - - - - - - - - - - - - - - - - word local b1, b2 = self:byte(2); return 0x100*b1 + b2; end function resolver:dword () -- - - - - - - - - - - - - - - - - - - - - dword local b1, b2, b3, b4 = self:byte(4); --print('dword', b1, b2, b3, b4); return 0x1000000*b1 + 0x10000*b2 + 0x100*b3 + b4; end function resolver:sub(len) -- - - - - - - - - - - - - - - - - - - - - - sub len = len or 1; local s = string.sub(self.packet, self.offset, self.offset + len - 1); self.offset = self.offset + len; return s; end function resolver:header(force) -- - - - - - - - - - - - - - - - - - header local id = self:word(); --print(string.format(':header id %x', id)); if not self.active[id] and not force then return nil; end local h = { id = id }; local b1, b2 = self:byte(2); h.rd = b1 %2; h.tc = b1 /2%2; h.aa = b1 /4%2; h.opcode = b1 /8%16; h.qr = b1 /128; h.rcode = b2 %16; h.z = b2 /16%8; h.ra = b2 /128; h.qdcount = self:word(); h.ancount = self:word(); h.nscount = self:word(); h.arcount = self:word(); for k,v in pairs(h) do h[k] = v-v%1; end return h; end function resolver:name() -- - - - - - - - - - - - - - - - - - - - - - name local remember, pointers = nil, 0; local len = self:byte(); local n = {}; if len == 0 then return "." end -- Root label while len > 0 do if len >= 0xc0 then -- name is "compressed" pointers = pointers + 1; if pointers >= 20 then error('dns error: 20 pointers'); end; local offset = ((len-0xc0)*0x100) + self:byte(); remember = remember or self.offset; self.offset = offset + 1; -- +1 for lua else -- name is not compressed append(n, self:sub(len)..'.'); end len = self:byte(); end self.offset = remember or self.offset; return table.concat(n); end function resolver:question() -- - - - - - - - - - - - - - - - - - question local q = {}; q.name = self:name(); q.type = dns.type[self:word()]; q.class = dns.class[self:word()]; return q; end function resolver:A(rr) -- - - - - - - - - - - - - - - - - - - - - - - - A local b1, b2, b3, b4 = self:byte(4); rr.a = string.format('%i.%i.%i.%i', b1, b2, b3, b4); end if have_util_net and util_net.ntop then function resolver:A(rr) rr.a = util_net.ntop(self:sub(4)); end end function resolver:AAAA(rr) local addr = {}; for _ = 1, rr.rdlength, 2 do local b1, b2 = self:byte(2); table.insert(addr, ("%02x%02x"):format(b1, b2)); end addr = table.concat(addr, ":"):gsub("%f[%x]0+(%x)","%1"); local zeros = {}; for item in addr:gmatch(":[0:]+:[0:]+:") do table.insert(zeros, item) end if #zeros == 0 then rr.aaaa = addr; return elseif #zeros > 1 then table.sort(zeros, function(a, b) return #a > #b end); end rr.aaaa = addr:gsub(zeros[1], "::", 1):gsub("^0::", "::"):gsub("::0$", "::"); end if have_util_net and util_net.ntop then function resolver:AAAA(rr) rr.aaaa = util_net.ntop(self:sub(16)); end end function resolver:CNAME(rr) -- - - - - - - - - - - - - - - - - - - - CNAME rr.cname = self:name(); end function resolver:MX(rr) -- - - - - - - - - - - - - - - - - - - - - - - MX rr.pref = self:word(); rr.mx = self:name(); end function resolver:LOC_nibble_power() -- - - - - - - - - - LOC_nibble_power local b = self:byte(); --print('nibbles', ((b-(b%0x10))/0x10), (b%0x10)); return ((b-(b%0x10))/0x10) * (10^(b%0x10)); end function resolver:LOC(rr) -- - - - - - - - - - - - - - - - - - - - - - LOC rr.version = self:byte(); if rr.version == 0 then rr.loc = rr.loc or {}; rr.loc.size = self:LOC_nibble_power(); rr.loc.horiz_pre = self:LOC_nibble_power(); rr.loc.vert_pre = self:LOC_nibble_power(); rr.loc.latitude = self:dword(); rr.loc.longitude = self:dword(); rr.loc.altitude = self:dword(); end end local function LOC_tostring_degrees(f, pos, neg) -- - - - - - - - - - - - - f = f - 0x80000000; if f < 0 then pos = neg; f = -f; end local deg, min, msec; msec = f%60000; f = (f-msec)/60000; min = f%60; deg = (f-min)/60; return string.format('%3d %2d %2.3f %s', deg, min, msec/1000, pos); end function resolver.LOC_tostring(rr) -- - - - - - - - - - - - - LOC_tostring local t = {}; --[[ for k,name in pairs { 'size', 'horiz_pre', 'vert_pre', 'latitude', 'longitude', 'altitude' } do append(t, string.format('%4s%-10s: %12.0f\n', '', name, rr.loc[name])); end --]] append(t, string.format( '%s %s %.2fm %.2fm %.2fm %.2fm', LOC_tostring_degrees (rr.loc.latitude, 'N', 'S'), LOC_tostring_degrees (rr.loc.longitude, 'E', 'W'), (rr.loc.altitude - 10000000) / 100, rr.loc.size / 100, rr.loc.horiz_pre / 100, rr.loc.vert_pre / 100 )); return table.concat(t); end function resolver:NS(rr) -- - - - - - - - - - - - - - - - - - - - - - - NS rr.ns = self:name(); end function resolver:SOA(rr) -- - - - - - - - - - - - - - - - - - - - - - SOA end function resolver:SRV(rr) -- - - - - - - - - - - - - - - - - - - - - - SRV rr.srv = {}; rr.srv.priority = self:word(); rr.srv.weight = self:word(); rr.srv.port = self:word(); rr.srv.target = self:name(); end function resolver:PTR(rr) rr.ptr = self:name(); end function resolver:TXT(rr) -- - - - - - - - - - - - - - - - - - - - - - TXT rr.txt = self:sub (self:byte()); end function resolver:rr() -- - - - - - - - - - - - - - - - - - - - - - - - rr local rr = {}; setmetatable(rr, rr_metatable); rr.name = self:name(self); rr.type = dns.type[self:word()] or rr.type; rr.class = dns.class[self:word()] or rr.class; rr.ttl = 0x10000*self:word() + self:word(); rr.rdlength = self:word(); rr.tod = self.time + math.max(rr.ttl, 1); local remember = self.offset; local rr_parser = self[dns.type[rr.type]]; if rr_parser then rr_parser(self, rr); end self.offset = remember; rr.rdata = self:sub(rr.rdlength); return rr; end function resolver:rrs (count) -- - - - - - - - - - - - - - - - - - - - - rrs local rrs = {}; for _ = 1, count do append(rrs, self:rr()); end return rrs; end function resolver:decode(packet, force) -- - - - - - - - - - - - - - decode self.packet, self.offset = packet, 1; local header = self:header(force); if not header then return nil; end local response = { header = header }; response.question = {}; local offset = self.offset; for _ = 1, response.header.qdcount do append(response.question, self:question()); end response.question.raw = string.sub(self.packet, offset, self.offset - 1); if not force then if not self.active[response.header.id] or not self.active[response.header.id][response.question.raw] then self.active[response.header.id] = nil; return nil; end end response.answer = self:rrs(response.header.ancount); response.authority = self:rrs(response.header.nscount); response.additional = self:rrs(response.header.arcount); return response; end -- socket layer -------------------------------------------------- socket layer resolver.delays = { 1, 2, 3, 5 }; resolver.jitter = have_timer and default_jitter or nil; resolver.retry_jitter = have_timer and default_retry_jitter or nil; function resolver:addnameserver(address) -- - - - - - - - - - addnameserver self.server = self.server or {}; append(self.server, address); end function resolver:setnameserver(address) -- - - - - - - - - - setnameserver self.server = {}; self:addnameserver(address); end function resolver:adddefaultnameservers() -- - - - - adddefaultnameservers if is_windows then if windows and windows.get_nameservers then for _, server in ipairs(windows.get_nameservers()) do self:addnameserver(server); end end if not self.server or #self.server == 0 then -- TODO log warning about no nameservers, adding opendns servers as fallback self:addnameserver("208.67.222.222"); self:addnameserver("208.67.220.220"); end else -- posix local resolv_conf = io.open("/etc/resolv.conf"); if resolv_conf then for line in resolv_conf:lines() do line = line:gsub("#.*$", "") :match('^%s*nameserver%s+([%x:%.]*%%?%S*)%s*$'); if line then local ip = new_ip(line); if ip then self:addnameserver(ip.addr); end end end resolv_conf:close(); end if not self.server or #self.server == 0 then -- TODO log warning about no nameservers, adding localhost as the default nameserver self:addnameserver("127.0.0.1"); end end end function resolver:getsocket(servernum) -- - - - - - - - - - - - - getsocket self.socket = self.socket or {}; self.socketset = self.socketset or {}; local sock = self.socket[servernum]; if sock then return sock; end local ok, err; local peer = self.server[servernum]; if peer:find(":") then sock, err = socket.udp6(); else sock, err = (socket.udp4 or socket.udp)(); end if sock and self.socket_wrapper then sock, err = self.socket_wrapper(sock, self); end if not sock then return nil, err; end sock:settimeout(0); -- todo: attempt to use a random port, fallback to 0 self.socket[servernum] = sock; self.socketset[sock] = servernum; -- set{sock,peer}name can fail, eg because of local routing table -- if so, try the next server ok, err = sock:setsockname('*', 0); if not ok then return self:servfail(sock, err); end ok, err = sock:setpeername(peer, 53); if not ok then return self:servfail(sock, err); end return sock; end function resolver:voidsocket(sock) if self.socket[sock] then self.socketset[self.socket[sock]] = nil; self.socket[sock] = nil; elseif self.socketset[sock] then self.socket[self.socketset[sock]] = nil; self.socketset[sock] = nil; end sock:close(); end function resolver:socket_wrapper_set(func) -- - - - - - - socket_wrapper_set self.socket_wrapper = func; end function resolver:closeall () -- - - - - - - - - - - - - - - - - - closeall for i,sock in ipairs(self.socket) do self.socket[i] = nil; self.socketset[sock] = nil; sock:close(); end end function resolver:remember(rr, type) -- - - - - - - - - - - - - - remember --print ('remember', type, rr.class, rr.type, rr.name) local qname, qtype, qclass = standardize(rr.name, rr.type, rr.class); if type ~= '*' then type = qtype; local all = get(self.cache, qclass, '*', qname); --print('remember all', all); if all then append(all, rr); end end self.cache = self.cache or setmetatable({}, cache_metatable); local rrs = get(self.cache, qclass, type, qname) or set(self.cache, qclass, type, qname, setmetatable({}, rrs_metatable)); if rr[qtype:lower()] and not rrs[rr[qtype:lower()]] then rrs[rr[qtype:lower()]] = true; append(rrs, rr); end if type == 'MX' then self.unsorted[rrs] = true; end end local function comp_mx(a, b) -- - - - - - - - - - - - - - - - - - - comp_mx return (a.pref == b.pref) and (a.mx < b.mx) or (a.pref < b.pref); end function resolver:peek (qname, qtype, qclass, n) -- - - - - - - - - - - - peek qname, qtype, qclass = standardize(qname, qtype, qclass); local rrs = get(self.cache, qclass, qtype, qname); if not rrs then if n then if n <= 0 then return end else n = 3 end rrs = get(self.cache, qclass, "CNAME", qname); if not (rrs and rrs[1]) then return end return self:peek(rrs[1].cname, qtype, qclass, n - 1); end if prune(rrs, socket.gettime()) and qtype == '*' or not next(rrs) then set(self.cache, qclass, qtype, qname, nil); return nil; end if self.unsorted[rrs] then table.sort (rrs, comp_mx); self.unsorted[rrs] = nil; end return rrs; end function resolver:purge(soft) -- - - - - - - - - - - - - - - - - - - purge if soft == 'soft' then self.time = socket.gettime(); for class,types in pairs(self.cache or {}) do for type,names in pairs(types) do for name,rrs in pairs(names) do prune(rrs, self.time, 'soft') end end end else self.cache = setmetatable({}, cache_metatable); end end function resolver:query(qname, qtype, qclass) -- - - - - - - - - - -- query qname, qtype, qclass = standardize(qname, qtype, qclass) local co = coroutine.running(); local q = get(self.wanted, qclass, qtype, qname); if co and q then -- We are already waiting for a reply to an identical query. set(self.wanted, qclass, qtype, qname, co, true); return true; end if not self.server then self:adddefaultnameservers(); end local question = encodeQuestion(qname, qtype, qclass); local peek = self:peek (qname, qtype, qclass); if peek then return peek; end local header, id = encodeHeader(); --print ('query id', id, qclass, qtype, qname) local o = { packet = header..question, server = self.best_server, delay = 1, retry = socket.gettime() + self.delays[1]; qclass = qclass; qtype = qtype; qname = qname; }; -- remember the query self.active[id] = self.active[id] or {}; self.active[id][question] = o; local conn, err = self:getsocket(o.server) if not conn then return nil, err; end if self.jitter then timer.add_task(math.random()*self.jitter, function () conn:send(o.packet); end); else conn:send(o.packet); end -- remember which coroutine wants the answer if co then set(self.wanted, qclass, qtype, qname, co, true); end if have_timer and self.timeout then local num_servers = #self.server; local i = 1; timer.add_task(self.timeout, function () if get(self.wanted, qclass, qtype, qname, co) then log("debug", "DNS request timeout %d/%d", i, num_servers) i = i + 1; self:servfail(self.socket[o.server]); -- end end -- Still outstanding? (i.e. retried) if get(self.wanted, qclass, qtype, qname, co) then return self.timeout; -- Then wait end end) end return true; end function resolver:servfail(sock, err) -- Resend all queries for this server local num = self.socketset[sock] -- Socket is dead now sock = self:voidsocket(sock); -- Find all requests to the down server, and retry on the next server self.time = socket.gettime(); log("debug", "servfail %d (of %d)", num, #self.server); for id,queries in pairs(self.active) do for question,o in pairs(queries) do if o.server == num then -- This request was to the broken server o.server = o.server + 1 -- Use next server if o.server > #self.server then o.server = 1; end o.retries = (o.retries or 0) + 1; local retried; if o.retries < #self.server then sock, err = self:getsocket(o.server); if sock then retried = true; if self.retry_jitter then local delay = self.delays[((o.retries-1)%#self.delays)+1] + (math.random()*self.retry_jitter); log("debug", "retry %d in %0.2fs", o.retries, delay); timer.add_task(delay, function () sock:send(o.packet); end); else log("debug", "retry %d (immediate)", o.retries); sock:send(o.packet); end end end if not retried then log("debug", 'tried all servers, giving up'); self:cancel(o.qclass, o.qtype, o.qname); queries[question] = nil; end end end if next(queries) == nil then self.active[id] = nil; end end if num == self.best_server then self.best_server = self.best_server + 1; if self.best_server > #self.server then -- Exhausted all servers, try first again self.best_server = 1; end end return sock, err; end function resolver:settimeout(seconds) self.timeout = seconds; end function resolver:receive(rset) -- - - - - - - - - - - - - - - - - receive --print('receive'); print(self.socket); self.time = socket.gettime(); rset = rset or self.socket; local response; for _, sock in pairs(rset) do if self.socketset[sock] then local packet = sock:receive(); if packet then response = self:decode(packet); if response and self.active[response.header.id] and self.active[response.header.id][response.question.raw] then --print('received response'); --self.print(response); for _, rr in pairs(response.answer) do if rr.name:sub(-#response.question[1].name, -1) == response.question[1].name then self:remember(rr, response.question[1].type) end end -- retire the query local queries = self.active[response.header.id]; queries[response.question.raw] = nil; if not next(queries) then self.active[response.header.id] = nil; end if not next(self.active) then self:closeall(); end -- was the query on the wanted list? local q = response.question[1]; local cos = get(self.wanted, q.class, q.type, q.name); if cos then for co in pairs(cos) do if coroutine.status(co) == "suspended" then coroutine.resume(co); end end set(self.wanted, q.class, q.type, q.name, nil); end end end end end return response; end function resolver:feed(sock, packet, force) --print('receive'); print(self.socket); self.time = socket.gettime(); local response = self:decode(packet, force); if response and self.active[response.header.id] and self.active[response.header.id][response.question.raw] then --print('received response'); --self.print(response); for _, rr in pairs(response.answer) do self:remember(rr, rr.type); end for _, rr in pairs(response.additional) do self:remember(rr, rr.type); end -- retire the query local queries = self.active[response.header.id]; queries[response.question.raw] = nil; if not next(queries) then self.active[response.header.id] = nil; end if not next(self.active) then self:closeall(); end -- was the query on the wanted list? local q = response.question[1]; if q then local cos = get(self.wanted, q.class, q.type, q.name); if cos then for co in pairs(cos) do if coroutine.status(co) == "suspended" then coroutine.resume(co); end end set(self.wanted, q.class, q.type, q.name, nil); end end end return response; end function resolver:cancel(qclass, qtype, qname) local cos = get(self.wanted, qclass, qtype, qname); if cos then for co in pairs(cos) do if coroutine.status(co) == "suspended" then coroutine.resume(co); end end set(self.wanted, qclass, qtype, qname, nil); end end function resolver:pulse() -- - - - - - - - - - - - - - - - - - - - - pulse --print(':pulse'); while self:receive() do end if not next(self.active) then return nil; end self.time = socket.gettime(); for id,queries in pairs(self.active) do for question,o in pairs(queries) do if self.time >= o.retry then o.server = o.server + 1; if o.server > #self.server then o.server = 1; o.delay = o.delay + 1; end if o.delay > #self.delays then --print('timeout'); queries[question] = nil; if not next(queries) then self.active[id] = nil; end if not next(self.active) then return nil; end else --print('retry', o.server, o.delay); local _a = self.socket[o.server]; if _a then _a:send(o.packet); end o.retry = self.time + self.delays[o.delay]; end end end end if next(self.active) then return true; end return nil; end function resolver:lookup(qname, qtype, qclass) -- - - - - - - - - - lookup self:query (qname, qtype, qclass) while self:pulse() do local recvt = {} for i, s in ipairs(self.socket) do recvt[i] = s end socket.select(recvt, nil, 4) end --print(self.cache); return self:peek(qname, qtype, qclass); end function resolver:lookupex(handler, qname, qtype, qclass) -- - - - - - - - - - lookup return self:peek(qname, qtype, qclass) or self:query(qname, qtype, qclass); end function resolver:tohostname(ip) return dns.lookup(ip:gsub("(%d+)%.(%d+)%.(%d+)%.(%d+)", "%4.%3.%2.%1.in-addr.arpa."), "PTR"); end --print ---------------------------------------------------------------- print local hints = { -- - - - - - - - - - - - - - - - - - - - - - - - - - - hints qr = { [0]='query', 'response' }, opcode = { [0]='query', 'inverse query', 'server status request' }, aa = { [0]='non-authoritative', 'authoritative' }, tc = { [0]='complete', 'truncated' }, rd = { [0]='recursion not desired', 'recursion desired' }, ra = { [0]='recursion not available', 'recursion available' }, z = { [0]='(reserved)' }, rcode = { [0]='no error', 'format error', 'server failure', 'name error', 'not implemented' }, type = dns.type, class = dns.class }; local function hint(p, s) -- - - - - - - - - - - - - - - - - - - - - - hint return (hints[s] and hints[s][p[s]]) or ''; end function resolver.print(response) -- - - - - - - - - - - - - resolver.print for _, s in pairs { 'id', 'qr', 'opcode', 'aa', 'tc', 'rd', 'ra', 'z', 'rcode', 'qdcount', 'ancount', 'nscount', 'arcount' } do print( string.format('%-30s', 'header.'..s), response.header[s], hint(response.header, s) ); end for i,question in ipairs(response.question) do print(string.format ('question[%i].name ', i), question.name); print(string.format ('question[%i].type ', i), question.type); print(string.format ('question[%i].class ', i), question.class); end local common = { name=1, type=1, class=1, ttl=1, rdlength=1, rdata=1 }; local tmp; for _, s in pairs({'answer', 'authority', 'additional'}) do for i,rr in pairs(response[s]) do for _, t in pairs({ 'name', 'type', 'class', 'ttl', 'rdlength' }) do tmp = string.format('%s[%i].%s', s, i, t); print(string.format('%-30s', tmp), rr[t], hint(rr, t)); end for j,t in pairs(rr) do if not common[j] then tmp = string.format('%s[%i].%s', s, i, j); print(string.format('%-30s %s', tostring(tmp), tostring(t))); end end end end end -- module api ------------------------------------------------------ module api function dns.resolver () -- - - - - - - - - - - - - - - - - - - - - resolver local r = { active = {}, cache = {}, unsorted = {}, wanted = {}, best_server = 1 }; setmetatable (r, resolver); setmetatable (r.cache, cache_metatable); setmetatable (r.unsorted, { __mode = 'kv' }); return r; end local _resolver = dns.resolver(); dns._resolver = _resolver; _resolver.jitter, _resolver.retry_jitter = false, false; function dns.lookup(...) -- - - - - - - - - - - - - - - - - - - - - lookup return _resolver:lookup(...); end function dns.tohostname(...) return _resolver:tohostname(...); end function dns.purge(...) -- - - - - - - - - - - - - - - - - - - - - - purge return _resolver:purge(...); end function dns.peek(...) -- - - - - - - - - - - - - - - - - - - - - - - peek return _resolver:peek(...); end function dns.query(...) -- - - - - - - - - - - - - - - - - - - - - - query return _resolver:query(...); end function dns.feed(...) -- - - - - - - - - - - - - - - - - - - - - - - feed return _resolver:feed(...); end function dns.cancel(...) -- - - - - - - - - - - - - - - - - - - - - - cancel return _resolver:cancel(...); end function dns.settimeout(...) return _resolver:settimeout(...); end function dns.cache() return _resolver.cache; end function dns.socket_wrapper_set(...) -- - - - - - - - - socket_wrapper_set return _resolver:socket_wrapper_set(...); end return dns;