--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/net/dns.lua Thu Dec 25 10:48:06 2014 +0000
@@ -0,0 +1,1104 @@
+-- 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 timer = require "util.timer";
+local new_ip = require "util.ip".new_ip;
+
+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, unpack, select, type=
+ ipairs, next, pairs, print, setmetatable, tostring, assert, error, unpack, 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 = 15;
+
+-------------------------------------------------- module dns
+module('dns')
+local dns = _M;
+
+
+-- 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) -- - - - - - - - - - - - - - - - - - - - augment
+ local a = {};
+ for i,s in pairs(t) do
+ a[i] = s;
+ a[s] = s;
+ a[string.lower(s)] = s;
+ 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 = {
+ 'A', 'NS', 'MD', 'MF', 'CNAME', 'SOA', 'MB', 'MG', 'MR', 'NULL', 'WKS',
+ 'PTR', 'HINFO', 'MINFO', 'MX', 'TXT',
+ [ 28] = 'AAAA', [ 29] = 'LOC', [ 33] = 'SRV',
+ [252] = 'AXFR', [253] = 'MAILB', [254] = 'MAILA', [255] = '*' };
+
+
+dns.classes = { 'IN', 'CS', 'CH', 'HS', [255] = '*' };
+
+
+dns.type = augment (dns.types);
+dns.class = augment (dns.classes);
+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
+ -- rr.tod = rr.tod - 50 -- accelerated decripitude
+ rr.ttl = math.floor(rr.tod - time);
+ if rr.ttl <= 0 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 "<UNKNOWN RDATA TYPE>";
+ 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 i,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
+
+
+function resolver:new() -- - - - - - - - - - - - - - - - - - - - - resolver
+ local r = { active = {}, cache = {}, unsorted = {} };
+ setmetatable(r, resolver);
+ setmetatable(r.cache, cache_metatable);
+ setmetatable(r.unsorted, { __mode = 'kv' });
+ return r;
+end
+
+
+-- packet layer -------------------------------------------------- packet layer
+
+
+function dns.random(...) -- - - - - - - - - - - - - - - - - - - dns.random
+ math.randomseed(math.floor(10000*socket.gettime()) % 0x100000000);
+ 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 resvered
+ 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
+
+function resolver:AAAA(rr)
+ local addr = {};
+ for i = 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:]+:") 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
+
+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();
+
+ if rr.ttl <= 0 then
+ rr.tod = self.time + 30;
+ else
+ rr.tod = self.time + rr.ttl;
+ end
+
+ 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 i = 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 i = 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, 3 };
+
+
+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*$');
+ if line then
+ local ip = new_ip(line);
+ if ip then
+ self:addnameserver(ip.addr);
+ end
+ end
+ end
+ 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.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 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) -- - - - - - - - - - - - peek
+ qname, qtype, qclass = standardize(qname, qtype, qclass);
+ local rrs = get(self.cache, qclass, qtype, qname);
+ if not rrs then return nil; 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); 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]
+ };
+
+ -- remember the query
+ self.active[id] = self.active[id] or {};
+ self.active[id][question] = o;
+
+ -- remember which coroutine wants the answer
+ if co then
+ set(self.wanted, qclass, qtype, qname, co, true);
+ end
+
+ local conn, err = self:getsocket(o.server)
+ if not conn then
+ return nil, err;
+ end
+ conn:send (o.packet)
+
+ if 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
+ if i < num_servers then
+ i = i + 1;
+ self:servfail(conn);
+ o.server = self.best_server;
+ conn, err = self:getsocket(o.server);
+ if conn then
+ conn:send(o.packet);
+ return self.timeout;
+ end
+ end
+ -- Tried everything, failed
+ self:cancel(qclass, qtype, qname);
+ 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();
+ 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;
+ if o.retries >= #self.server then
+ --print('timeout');
+ queries[question] = nil;
+ else
+ sock, err = self:getsocket(o.server);
+ if sock then sock:send(o.packet); end
+ 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 i,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 j,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 j,rr in pairs(response.answer) do
+ self:remember(rr, response.question[1].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,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,s in pairs({'answer', 'authority', 'additional'}) do
+ for i,rr in pairs(response[s]) do
+ for j,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
+ -- this function seems to be redundant with resolver.new ()
+
+ 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;
+
+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;