159 lines
3.5 KiB
JavaScript
159 lines
3.5 KiB
JavaScript
/**
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* ip2region client for nodejs
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*
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* project: https://github.com/lionsoul2014/ip2region
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*
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* @author dongyado<dongyado@gmail.com>
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* */
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var fs = require('fs');
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var ipbase = [16777216, 65536, 256, 1]; // for ip2long
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var ip2region = {};
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ip2region.db_file_path = null;
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ip2region.db_fd = null;
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var totalBlocks = 0;
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var firstIndexPtr = 0;
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var lastIndexPtr = 0;
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var superBlock = new Buffer(8);
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var indexBlockLength = 12;
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var totalHeaderLength = 4096;
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/**
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* binary search
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* */
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ip2region.binarySearch = function(ip)
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{
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if( typeof(ip) == 'string' )
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ip = ip2long(ip);
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// search
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var low = 0;
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var mid = 0;
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var high = totalBlocks;
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var dataPos = 0;
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var pos = 0;
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var sip = 0;
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var eip = 0;
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var indexBuffer = new Buffer(12);
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// binary search
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while( low <= high ) {
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mid = ((low + high) >> 1);
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pos = firstIndexPtr + mid * indexBlockLength;
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fs.readSync(this.db_fd, indexBuffer, 0, indexBlockLength, pos);
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sip = getLong(indexBuffer, 0);
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//console.log( ' sip : ' + sip + ' eip : ' + eip );
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if ( ip < sip) {
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high = mid - 1;
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} else {
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eip = getLong(indexBuffer, 4);
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if ( ip > eip ) {
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low = mid + 1;
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} else {
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dataPos = getLong(indexBuffer, 8);
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break;
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}
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}
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}
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// read data
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if (dataPos == 0) return null;
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var dataLen = ((dataPos >> 24) & 0xFF);
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var dataPos = (dataPos & 0x00FFFFFF);
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var dataBuffer = new Buffer(dataLen);
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fs.readSync(this.db_fd, dataBuffer, 0, dataLen, dataPos);
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var city_id = getLong(dataBuffer, 0);
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var data = dataBuffer.toString('utf8', 4, dataLen);
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//console.log(city_id);
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//console.log(data);
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return { city: city_id, region: data };
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}
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/**
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* btree search
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* */
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ip2region.btreeSearch = function(ip)
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{
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return ip2long(ip);
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}
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/**
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* convert ip to long (xxx.xxx.xxx.xxx to a integer)
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* */
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function ip2long(ip)
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{
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var val = 0;
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ip.split('.').forEach(function(ele, i){
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val += ipbase[i] * ele;
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});
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return val;
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}
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/**
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* get long value from buffer with specified offset
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* */
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function getLong(buffer, offset)
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{
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var val = (
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(buffer[offset] & 0x000000FF) |
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((buffer[offset + 1] << 8) & 0x0000FF00) |
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((buffer[offset + 2] << 16) & 0x00FF0000) |
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((buffer[offset + 3] << 24) & 0xFF000000)
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);
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// convert to unsigned int
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if (val < 0) {
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val = val >>> 0;
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}
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return val;
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}
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// api for create
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exports.create = function(db_path) {
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// db file check
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if (typeof(db_path) == "undefined" || fs.exists(db_path) ) {
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throw("[ip2region] db file not exists : " + db_path);
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}
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ip2region.db_file_path = db_path;
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try {
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ip2region.db_fd = fs.openSync(ip2region.db_file_path, 'r');
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} catch(e) {
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throw("[ip2region] Can not open ip2region.db file , path : "
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+ ip2region.db_file_path);
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}
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// init basic search environment
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if (totalBlocks == 0) {
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fs.readSync(ip2region.db_fd, superBlock, 0, 8, 0);
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firstIndexPtr = getLong(superBlock, 0);
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lastIndexPtr = getLong(superBlock, 4);
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totalBlocks = (lastIndexPtr - firstIndexPtr)
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/ indexBlockLength + 1;
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}
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return ip2region;
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}
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// api for destroy
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exports.destroy = function(ip2rObj){
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ip2rObj.db_file_path = null;
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fs.closeSync(ip2rObj.db_fd);
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}
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