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geoip-lite#41 Reverse geocode feature request
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‎lib/geohash.js

+114
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@@ -0,0 +1,114 @@
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var geohash = module.exports = {};
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// geohash.js
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// Geohash library for Javascript
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// (c) 2008 David Troy
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// Distributed under the MIT License
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BITS = [16, 8, 4, 2, 1];
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BASE32 = "0123456789bcdefghjkmnpqrstuvwxyz";
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NEIGHBORS = { right : { even : "bc01fg45238967deuvhjyznpkmstqrwx" },
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left : { even : "238967debc01fg45kmstqrwxuvhjyznp" },
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top : { even : "p0r21436x8zb9dcf5h7kjnmqesgutwvy" },
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bottom : { even : "14365h7k9dcfesgujnmqp0r2twvyx8zb" } };
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BORDERS = { right : { even : "bcfguvyz" },
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left : { even : "0145hjnp" },
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top : { even : "prxz" },
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bottom : { even : "028b" } };
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NEIGHBORS.bottom.odd = NEIGHBORS.left.even;
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NEIGHBORS.top.odd = NEIGHBORS.right.even;
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NEIGHBORS.left.odd = NEIGHBORS.bottom.even;
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NEIGHBORS.right.odd = NEIGHBORS.top.even;
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BORDERS.bottom.odd = BORDERS.left.even;
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BORDERS.top.odd = BORDERS.right.even;
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BORDERS.left.odd = BORDERS.bottom.even;
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BORDERS.right.odd = BORDERS.top.even;
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geohash.refine_interval = function(interval, cd, mask) {
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if(cd & mask)
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interval[0] = (interval[0] + interval[1])/2;
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else
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interval[1] = (interval[0] + interval[1])/2;
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}
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geohash.calculateAdjacent = function(srcHash, dir) {
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srcHash = srcHash.toLowerCase();
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var lastChr = srcHash.charAt(srcHash.length-1);
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var type = (srcHash.length % 2) ? 'odd' : 'even';
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var base = srcHash.substring(0,srcHash.length-1);
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if (BORDERS[dir][type].indexOf(lastChr)!=-1)
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base = geohash.calculateAdjacent(base, dir);
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return base + BASE32[NEIGHBORS[dir][type].indexOf(lastChr)];
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}
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geohash.decodeGeoHash = function(hash) {
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var is_even = 1;
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var lat = []; var lon = [];
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lat[0] = -90.0; lat[1] = 90.0;
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lon[0] = -180.0; lon[1] = 180.0;
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lat_err = 90.0; lon_err = 180.0;
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for (i=0; i<hash.length; i++) {
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c = hash[i];
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cd = BASE32.indexOf(c);
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for (j=0; j<5; j++) {
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mask = BITS[j];
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if (is_even) {
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lon_err /= 2;
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geohash.refine_interval(lon, cd, mask);
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} else {
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lat_err /= 2;
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geohash.refine_interval(lat, cd, mask);
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}
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is_even = !is_even;
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}
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}
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lat[2] = (lat[0] + lat[1])/2;
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lon[2] = (lon[0] + lon[1])/2;
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return { latitude: lat, longitude: lon};
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}
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geohash.encodeGeoHash = function(latitude, longitude) {
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var is_even=1;
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var i=0;
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var lat = []; var lon = [];
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var bit=0;
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var ch=0;
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var precision = 12;
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hash = "";
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lat[0] = -90.0; lat[1] = 90.0;
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lon[0] = -180.0; lon[1] = 180.0;
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while (hash.length < precision) {
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if (is_even) {
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mid = (lon[0] + lon[1]) / 2;
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if (longitude > mid) {
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ch |= BITS[bit];
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lon[0] = mid;
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} else
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lon[1] = mid;
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} else {
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mid = (lat[0] + lat[1]) / 2;
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if (latitude > mid) {
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ch |= BITS[bit];
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lat[0] = mid;
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} else
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lat[1] = mid;
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}
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is_even = !is_even;
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if (bit < 4)
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bit++;
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else {
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hash += BASE32[ch];
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bit = 0;
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ch = 0;
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}
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}
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return hash;
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}

‎lib/geoip.js

+106
Original file line numberDiff line numberDiff line change
@@ -1,10 +1,12 @@
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var fs = require('fs');
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var net = require('net');
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var path = require('path');
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var Triejs = require('triejs');
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fs.existsSync = fs.existsSync || path.existsSync;
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var utils = require('./utils');
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var geohash = require('./geohash');
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var fsWatcher = require('./fsWatcher');
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var async = require('async');
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@@ -51,6 +53,8 @@ var cache6 = {
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recordSize: 58
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};
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var locationTrie = null;
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var RECORD_SIZE = 10;
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var RECORD_SIZE6 = 34
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@@ -201,6 +205,64 @@ function lookup6(ip) {
201205
} while(1);
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}
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function info(lat, lon) {
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var precision = 4; //found this value optimal
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var hash = geohash.encodeGeoHash(lat, lon);
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var boundary = hash.substring(0, precision);
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var searches = [boundary, geohash.calculateAdjacent(boundary, 'top'),
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geohash.calculateAdjacent(boundary, 'bottom'),
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geohash.calculateAdjacent(boundary, 'right'),
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geohash.calculateAdjacent(boundary, 'left')];
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var results = [];
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for (var i = 0; i < searches.length; i++) {
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var result = locationTrie.find(searches[i]);
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if(result != undefined) {
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results = results.concat(result);
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}
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}
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var found = null;
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var foundDistance = 0;
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if(results != undefined) {
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for(var i = 0; i < results.length; i++) {
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if(found == null) {
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found = results[i];
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foundDistance = utils.distance(lat, lon, found.ll[0], found.ll[1]);
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} else {
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var f = results[i];
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var d = utils.distance(lat, lon, f.ll[0], f.ll[1]);
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if(d < foundDistance) {
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found = f;
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foundDistance = d;
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}
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}
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}
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}
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if(!found) {
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return null;
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}
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var result = {
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country: found.country,
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city: found.city,
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region: found.region,
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ll: found.ll,
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distance: foundDistance,
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};
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return result;
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}
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function preload(callback) {
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var datFile;
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var datSize;
@@ -425,9 +487,49 @@ function preload6(callback) {
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}
426488
}
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function preloadLocations(callback) {
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var locBuffer = cache4.locationBuffer;
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var locRecordSize = cache4.locationRecordSize;
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var line;
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locationTrie = new Triejs();
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var locNumber = locBuffer.length / locRecordSize;
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for(var locId = 0; locId < locNumber; locId++) {
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var ll = [locBuffer.readInt32BE((locId * locRecordSize) + 4) / 10000, locBuffer.readInt32BE((locId * locRecordSize) + 8) / 10000];
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var hash = geohash.encodeGeoHash(ll[0], ll[1])
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if(locationTrie.find(hash) == undefined) {
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var country = locBuffer.toString('utf8', (locId * locRecordSize) + 0, (locId * locRecordSize) + 2).replace(/\u0000.*/, '');
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var region = locBuffer.toString('utf8', (locId * locRecordSize) + 2, (locId * locRecordSize) + 4).replace(/\u0000.*/, '');
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var city = locBuffer.toString('utf8', (locId * locRecordSize) + 12, (locId * locRecordSize) + locRecordSize).replace(/\u0000.*/, '');
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var l = {
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country: country,
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region: region,
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city: city,
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ll: ll,
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};
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locationTrie.add(hash, l);
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}
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}
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if (typeof arguments[0] === 'function') {
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//nothing to be done for now
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}
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}
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module.exports = {
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cmp: utils.cmp,
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info: function(lat, lon) {
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return info(lat, lon);
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},
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lookup: function(ip) {
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if (!ip) {
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return null;
@@ -465,6 +567,9 @@ module.exports = {
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},
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function (cb) {
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preload6(cb);
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},
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function (cb) {
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preloadLocations(cb);
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}
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]);
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});
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preload();
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preload6();
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preloadLocations();
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//lookup4 = gen_lookup('geoip-country.dat', 4);
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//lookup6 = gen_lookup('geoip-country6.dat', 16);

‎lib/utils.js

+18-1
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@@ -95,4 +95,21 @@ utils.ntoa6 = function(n) {
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a = a.replace(/:$/, ']').replace(/:0+/g, ':').replace(/::+/, '::');
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return a;
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};
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};
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utils.toRad = function(v) {
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return v * Math.PI / 180;
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}
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utils.distance = function(lat1, lon1, lat2, lon2) {
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var R = 6371; // km
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var dLat = utils.toRad(lat2-lat1);
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var dLon = utils.toRad(lon2-lon1);
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var lat1 = utils.toRad(lat1);
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var lat2 = utils.toRad(lat2);
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var a = Math.sin(dLat/2) * Math.sin(dLat/2) +
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Math.sin(dLon/2) * Math.sin(dLon/2) * Math.cos(lat1) * Math.cos(lat2);
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var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
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return R * c;
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}

‎package.json

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"iconv-lite": "~0.2.11",
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"lazy": "~1.0.11",
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"rimraf": "~2.0.2",
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"unzip": "~0.0.4"
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"unzip": "~0.0.4",
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"triejs": "~0.1.5"
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},
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"devDependencies": {
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"nodeunit": "~0.7.4"

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