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dns.js 17.30 KiB
/* DNS protocol library
* Uses events, so the calling script *MUST* set js.do_callbacks
* Example usage:
*
* js.do_callbacks = true;
* load('dns.js');
*
* function handle(resp)
* {
* log(LOG_ERROR, JSON.stringify(resp));
* exit(0);
* }
*
* dns.resolve('example.com', handle);
*
*/
require('sockdefs.js', 'SOCK_DGRAM');
function DNS(servers) {
if (servers === undefined)
servers = system.name_servers;
var nextid = 0;
var outstanding = {};
this.sockets = [];
handle_response = function() {
var resp;
var id;
var offset = 0;
var queries;
var answers;
var nameservers;
var arecords;
var q;
var i;
var ret = {'queries':[], 'answers':[], 'nameservers':[], 'additional':[]};
var rdata;
var rdlen;
var tmp;
string_to_int16 = function(str) {
return ((ascii(str[0])<<8) | (ascii(str[1])));
}
string_to_int32 = function(str) {
return ((ascii(str[0])<<24) | (ascii(str[1]) << 16) | (ascii(str[1]) << 8) | (ascii(str[1])));
}
function get_string(resp, offset) {
var len = ascii(resp[offset]);
return {'len':len + 1, 'string':resp.substr(offset + 1, len)};
}
function get_name(resp, offset) {
var len;
var name = '';
var ret = 0;
var compressed = false;
do {
len = ascii(resp[offset]);
if (!compressed)
ret++;
offset++;
if (len > 63) {
offset = ((len & 0x3f) << 8) | ascii(resp[offset]);
if (!compressed)
ret++;
compressed = true; }
else {
if (!compressed)
ret += len;
if (name.length > 0 && len > 0)
name += '.';
name += resp.substr(offset, len);
offset += len;
}
} while (len != 0);
return {'len':ret, 'name':name};
}
function parse_rdata(type, resp, offset, len) {
var tmp;
var tmp2;
var tmp3;
var tmp4;
switch(type) {
case 1: // A
return ascii(resp[offset]) + '.' +
ascii(resp[offset + 1]) + '.' +
ascii(resp[offset + 2]) + '.' +
ascii(resp[offset + 3]);
case 2: // NS
return get_name(resp, offset).name;
case 5: // CNAME
return get_name(resp, offset).name;
case 6: // SOA
tmp = {};
tmp2 = 0;
tmp3 = get_name(resp, offset + tmp2);
tmp.mname = tmp3.name;
tmp2 += tmp3.len;
tmp3 = get_name(resp, offset + tmp2);
tmp.rname = tmp3.name;
tmp2 += tmp3.len;
tmp.serial = string_to_int32(resp.substr(offset + tmp2, 4));
tmp2 += 4;
tmp.refresh = string_to_int32(resp.substr(offset + tmp2, 4));
tmp2 += 4;
tmp.retry = string_to_int32(resp.substr(offset + tmp2, 4));
tmp2 += 4;
tmp.export = string_to_int32(resp.substr(offset + tmp2, 4));
tmp2 += 4;
tmp.minimum = string_to_int32(resp.substr(offset + tmp2, 4));
tmp2 += 4;
return tmp;
case 11: // WKS
tmp = {};
tmp.address = ascii(resp[offset]) + '.' +
ascii(resp[offset + 1]) + '.' +
ascii(resp[offset + 2]) + '.' +
ascii(resp[offset + 3]);
tmp.protocol = ascii(resp[offset + 4]);
tmp2 = 5;
tmp.ports = [];
while (tmp2 < len) {
tmp3 = ascii(resp[offset + tmp2]);
for (tmp4 = 0; tmp4 < 8; tmp4++) {
if (tmp3 & (1 << tmp4))
tmp.ports.push(8 * (tmp2 - 5) + tmp3);
}
}
return tmp;
case 12: // PTR
return get_name(resp, offset).name;
case 13: // HINFO tmp = get_string(resp, offset);
return {'cpu':tmp.string, 'os':get_string(resp, offset + tmp.len).string};
case 15: // MX
tmp = {};
tmp.preference = string_to_int16(resp.substr(offset, 2));
tmp.exchange = get_name(resp, offset + 2).name;
return tmp;
case 16: // TXT
tmp = [];
tmp2 = 0;
do {
tmp3 = get_string(resp, offset + tmp2);
tmp.push(tmp3.string);
tmp2 += tmp3.len;
} while (tmp2 < len);
return tmp;
case 28: // AAAA
return format("%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x",
ascii(resp[offset + 0]), ascii(resp[offset + 1]),
ascii(resp[offset + 2]), ascii(resp[offset + 3]),
ascii(resp[offset + 4]), ascii(resp[offset + 5]),
ascii(resp[offset + 6]), ascii(resp[offset + 7]),
ascii(resp[offset + 8]), ascii(resp[offset + 9]),
ascii(resp[offset + 10]), ascii(resp[offset + 11]),
ascii(resp[offset + 12]), ascii(resp[offset + 13]),
ascii(resp[offset + 14]), ascii(resp[offset + 15])
).replace(/(0000:)+/, ':').replace(/(^|:)0{1,3}/g, '$1');
case 33: // SRV
tmp = {};
tmp.priority = string_to_int16(resp.substr(offset, 2));
offset += 2;
tmp.weight = string_to_int16(resp.substr(offset, 2));
offset += 2;
tmp.port = string_to_int16(resp.substr(offset, 2));
offset += 2;
tmp.target = get_name(resp, offset).name;
return tmp;
case 35: // NAPTR
tmp = {};
tmp.order = string_to_int16(resp.substr(offset, 2));
offset += 2;
tmp.preference = string_to_int16(resp.substr(offset, 2));
offset += 2;
tmp2 = get_string(resp, offset);
tmp.flags = tmp2.string;
offset += tmp2.len;
tmp2 = get_string(resp, offset);
tmp.services = tmp2.string;
offset += tmp2.len;
tmp2 = get_string(resp, offset);
tmp.regexp = tmp2.string;
offset += tmp2.len;
tmp.replacement = get_name(resp, offset).name;
return tmp;
case 256: // URI
tmp = {};
tmp.priority = string_to_int16(resp.substr(offset, 2));
offset += 2;
tmp.weight = string_to_int16(resp.substr(offset, 2));
offset += 2;
tmp.target = get_string(resp, offset).string;
tmp.target = tmp.target.replace(/\\"/g, '"');
tmp.target = tmp.target.replace(/^"(.*)"$/, '$1');
return tmp;
case 3: // MD
case 4: // MF
case 7: // MB
case 8: // MG
case 9: // MR
case 10: // NULL case 14: // MINFO
return {'raw':resp.substr(offset, len)};
}
}
resp = this.recv(10000);
id = string_to_int16(resp);
if (this.outstanding[id] === undefined)
return false;
q = this.outstanding[id];
delete this.outstanding[id];
ret.id = id;
ret.response = !!(ascii(resp[2]) & 1);
ret.opcode = (ascii(resp[2]) & 0x1e) >> 1;
ret.authoritative = !!(ascii(resp[2]) & (1<<5));
ret.truncation = !!(ascii(resp[2]) & (1<<6));
ret.recusrion = !!(ascii(resp[2]) & (1<<7));
ret.reserved = ascii(resp[3]) & 7;
ret.rcode = ascii(resp[3] & 0xf1) >> 3;
queries = string_to_int16(resp.substr(4, 2));
answers = string_to_int16(resp.substr(6, 2));
nameservers = string_to_int16(resp.substr(8, 2));
arecords = string_to_int16(resp.substr(10, 2));
if (answers === 0)
return false;
js.clearTimeout(q.timeoutid);
offset = 12;
for (i = 0; i < queries; i++) {
rdata = {};
tmp = get_name(resp, offset);
rdata.name = tmp.name;
offset += tmp.len;
rdata.type = string_to_int16(resp.substr(offset, 2));
offset += 2;
rdata.class = string_to_int16(resp.substr(offset, 2));
offset += 2;
ret.queries.push(rdata);
}
for (i = 0; i < answers; i++) {
rdata = {};
tmp = get_name(resp, offset);
rdata.name = tmp.name;
offset += tmp.len;
rdata.type = string_to_int16(resp.substr(offset, 2));
offset += 2;
rdata.class = string_to_int16(resp.substr(offset, 2));
offset += 2;
rdata.ttl = string_to_int32(resp.substr(offset, 4));
offset += 4;
rdlen = string_to_int16(resp.substr(offset, 2));
offset += 2;
rdata.rdata = parse_rdata(rdata.type, resp, offset, rdlen);
offset += rdlen;
ret.answers.push(rdata);
}
for (i = 0; i < nameservers; i++) {
rdata = {};
tmp = get_name(resp, offset);
rdata.name = tmp.name;
offset += tmp.len;
rdata.type = string_to_int16(resp.substr(offset, 2));
offset += 2;
rdata.class = string_to_int16(resp.substr(offset, 2));
offset += 2;
rdata.ttl = string_to_int32(resp.substr(offset, 4)); offset += 4;
rdlen = string_to_int16(resp.substr(offset, 2));
offset += 2;
rdata.rdata = parse_rdata(rdata.type, resp, offset, rdlen);
offset += rdlen;
ret.nameservers.push(rdata);
}
for (i = 0; i < arecords; i++) {
rdata = {};
tmp = get_name(resp, offset);
rdata.name = tmp.name;
offset += tmp.len;
rdata.type = string_to_int16(resp.substr(offset, 2));
offset += 2;
rdata.class = string_to_int16(resp.substr(offset, 2));
offset += 2;
rdata.ttl = string_to_int32(resp.substr(offset, 4));
offset += 4;
rdlen = string_to_int16(resp.substr(offset, 2));
offset += 2;
rdata.rdata = parse_rdata(rdata.type, resp, offset, rdlen);
offset += rdlen;
ret.additional.push(rdata);
}
q.callback.call(q.thisObj, ret);
return true;
}
servers.forEach(function(server) {
var sock = new Socket(SOCK_DGRAM, "dns", server.indexOf(':') >= 0);
sock.bind();
sock.connect(server, 53);
sock.on('read', handle_response);
sock.outstanding = outstanding;
this.sockets.push(sock);
}, this);
if (this.sockets.length < 1)
throw('Unable to create any sockets');
increment_id = function() {
var ret = nextid;
do {
nextid++;
if (nextid > 65535)
nextid = 0;
} while (outstanding[nextid] !== undefined);
return ret;
}
}
DNS.types = {
'A':1,
'NS':2,
'MD':3,
'MF':4,
'CNAME':5,
'SOA':6,
'MB':7,
'MG':8,
'MR':9,
'NULL':10,
'WKS':11,
'PTR':12,
'HINFO':13,
'MINFO':14,
'MX':15, 'TXT':16,
'AAAA':28,
'SRV':33,
'NAPTR':35,
'URI':256
};
DNS.classes = {
'IN':1,
'CS':2,
'CH':3,
'HS':4
};
DNS.prototype.query = function(queries, /* queryStr, type, class, */callback, thisObj, recursive, timeout, failures, failed) {
var id;
var namebits = {};
function int16_to_string(id) {
return ascii((id & 0xff00) >> 8) + ascii(id & 0xff);
}
function handle_timeout() {
this.failed++;
delete outstanding[this.id];
if (this.failed > 2)
this.callback.call(this);
else
this.obj.query(this.query, this.callback, this.thisObj, this.recursive, this.timeout, this.failures, this.failed);
}
queries.forEach(function(query) {
if (query.str === undefined)
query.str = 'example.com';
if (query.type === undefined)
query.type = 'AAAA';
if (DNS.types[query.type] !== undefined)
query.type = DNS.types[query.type];
query.type = parseInt(query.type, 10);
if (isNaN(query.type)) {
throw new Error('Invalid type');
}
if (query.class === undefined)
query.class = 'IN';
if (DNS.classes[query.class] !== undefined)
query.class = DNS.classes[query.class];
query.class = parseInt(query.class, 10);
if (isNaN(query.class)) {
throw new Error('Invalid class');
}
});
if (callback === undefined)
return;
if (recursive === undefined)
recursive = true;
if (timeout === undefined)
timeout = 1000;
if (failures === undefined)
failures = 1;
if (failed === undefined)
failed = 0;
var query = '';
// Header
id = increment_id();
query = int16_to_string(id); query += ascii(recursive ? 1 : 0);
query += ascii(0);
query += int16_to_string(queries.length); // Questions
query += int16_to_string(0); // Answers
query += int16_to_string(0); // Name Servers
query += int16_to_string(0); // Additional Records
// Queries
queries.forEach(function(oneQuery) {
var thisname = '';
var fields = oneQuery.query.split(/\./).reverse();
var matched;
fields.forEach(function(field) {
if (field.length > 63)
throw new Error('invalid field in query "'+field+'" (longer than 63 characters)');
thisname = ascii(field.length) + field + thisname;
if (namebits[thisname] !== undefined && namebits[thisname] > 0) {
matched = {'offset':namebits[thisname], 'length':thisname.length};
}
else {
namebits[thisname] = 0 - thisname.length;
}
});
// Now fix up negative namebits...
Object.keys(namebits).forEach(function(name) {
if (namebits[name] < 0) {
namebits[name] = query.length + thisname.length + namebits[name];
}
});
// And use the match
if (matched !== undefined) {
thisname = thisname.substr(0, thisname.length - matched.length);
thisname = thisname + ascii(0xc0 | ((matched.offset & 0x3f) >> 8)) + ascii(matched.offset & 0xff);
}
else
thisname += ascii(0);
query += thisname;
query += int16_to_string(oneQuery.type);
query += int16_to_string(oneQuery.class);
}, this);
this.sockets[0].outstanding[id] = {'callback':callback, 'query':queries, 'recursive':recursive, 'timeout':timeout, 'thisObj':thisObj, 'id':id, 'obj':this, 'failed':failed};
this.sockets[0].outstanding[id].timeoutid = js.setTimeout(handle_timeout, timeout, this.sockets[0].outstanding[id]);
this.sockets.forEach(function(sock) {
sock.write(query);
});
}
DNS.prototype.resolve = function(host, callback, thisObj)
{
var ctx = {A:{}, AAAA:{}, unique_id:'DNS.prototype.resolve'};
var final;
var respA;
var respAAAA;
this.sockets.forEach(function(sock) {
ctx.unique_id += '.'+sock.local_port;
});
if (host === undefined)
throw new Error('No host specified');
if (thisObj === undefined)
thisObj = this;
ctx.callback = callback; ctx.thisObj = thisObj;
ctx.final = js.addEventListener(ctx.unique_id+'.final', function() {
var ret = [];
this.AAAA.addrs.forEach(function(addr) {
ret.push(addr);
});
this.A.addrs.forEach(function(addr) {
ret.push(addr);
});
js.removeEventListener(this.final);
js.removeEventListener(this.respA);
js.removeEventListener(this.respAAAA);
this.callback.call(this.thisObj, ret);
});
ctx.respA = js.addEventListener(ctx.unique_id+'.respA', function() {
this.A.done = true;
if (this.AAAA.done)
js.dispatchEvent(this.unique_id + '.final', this);
});
ctx.respAAAA = js.addEventListener(ctx.unique_id+'.respAAAA', function() {
this.AAAA.done = true;
if (this.A.done)
js.dispatchEvent(ctx.unique_id + '.final', this);
});
function handle_response(resp) {
var rectype;
switch(resp.queries[0].type) {
case DNS.types.A:
rectype = 'A';
break;
case DNS.types.AAAA:
rectype = 'AAAA';
break;
};
if (rectype === undefined)
return;
this[rectype].addrs = [];
resp.answers.forEach(function(ans) {
if (resp.queries[0].type != ans.type || resp.queries[0].class != ans.class)
return;
this[rectype].addrs.push(ans.rdata);
}, this);
js.dispatchEvent(this.unique_id + '.resp'+rectype, this);
}
this.query([{query:host, type:'AAAA'}], handle_response, ctx);
this.query([{query:host, type:'A'}], handle_response, ctx);
}
DNS.prototype.resolveTypeClass = function(host, type, class, callback, thisObj)
{
var ctx = {};
var final;
var respA;
var respAAAA;
this.sockets.forEach(function(sock) {
ctx.unique_id += '.'+sock.local_port;
});
if (host === undefined)
throw new Error('No host specified');
if (type === undefined) throw new Error('No type specified');
if (class === undefined)
throw new Error('No class specified');
if (callback === undefined)
throw new Error('No callback specified');
ctx.callback = callback;
if (thisObj === undefined)
thisObj = this;
ctx.thisObj = thisObj;
function handle_response(resp) {
ret = [];
if (resp !== undefined && resp.answers !== undefined) {
resp.answers.forEach(function(ans) {
if (resp.queries[0].type != ans.type || resp.queries[0].class != ans.class)
return;
ret.push(ans.rdata);
});
}
this.callback.call(this.thisObj, ret);
}
this.query([{query:host, type:type, class:class}], handle_response, ctx);
}
DNS.prototype.reverse = function(ip, callback, thisObj)
{
var qstr;
var m;
var a;
var fillpos;
if (ip === undefined)
throw new Error('No IP specified');
if (thisObj === undefined)
thisObj = this;
// Sure, this doesn't deal with terrible ipv4-mapped representations. Suck it.
m = ip.match(/^(?:::ffff:)?([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3})$/i);
if (m !== null) {
// IPv4 Address
if (parseInt(m[1], 10) > 255 || parseInt(m[2], 10) > 255 || parseInt(m[3], 10) > 255 || parseInt(m[4], 10) > 255)
throw new Error('Malformed IP address '+ip);
qstr = m[4] + '.' + m[3] + '.' + m[2] + '.' + m[1] + '.in-addr.arpa';
}
else {
a = ip.split(/:/);
if (a.length < 3 || a.length > 8)
throw new Error('Malformed IP address '+ip);
if (ip.search(/^[a-fA-F0-9:]+$/) != 0)
throw new Error('Malformed IP address '+ip);
a.forEach(function(piece, idx, arr) {
if (piece !== '') {
while (piece.length < 4)
piece = '0'+piece;
}
arr[idx] = piece;
});
if (a[0] == '')
a[0] = '0000';
if (a[a.length - 1] == '')
a[a.length] = '0000';
while (a.length < 8) {
fillpos = a.indexOf('');
if (fillpos === -1)
throw('Unable to expand IPv6 address'); a.splice(fillpos, 0, '0000');
}
fillpos = a.indexOf('');
if (fillpos != -1)
a.splice(fillpos, 1, '0000');
a.reverse();
qstr = '';
a.forEach(function(piece) {
qstr += piece[3] + '.' + piece[2] + '.' + piece[1] + '.' + piece[0] + '.';
});
qstr += 'ip6.arpa';
}
this.resolveTypeClass(qstr, 'PTR', 'IN', callback, thisObj);
}
DNS.prototype.resolveMX = function(host, callback, thisObj)
{
var ctx = {callback:callback};
var qstr;
var m;
var a;
var fillpos;
if (host === undefined)
throw new Error('No host specified');
if (thisObj === undefined)
thisObj = this;
ctx.thisObj = thisObj;
function handler(resp) {
var ret = [];
resp.sort(function(a, b) {
return a.preference - b.preference;
});
resp.forEach(function(r) {
ret.push(r.exchange);
});
this.callback.call(this.thisObj, ret);
}
this.resolveTypeClass(host, 'MX', 'IN', handler, ctx);
}