nodejs client finish binary search

binding/nodejs/ip2region.js

@@ -1,86 +1,158 @@
 /**
  * ip2region client for nodejs
  *
- * project: https://github.com/lionsoul2016/ip2region
+ * project: https://github.com/lionsoul2014/ip2region
  *
  * @author dongyado<dongyado@gmail.com>
  * */
+var fs   = require('fs');
+
+var ipbase = [16777216, 65536, 256, 1]; // for ip2long
+var ip2region = {};
+ip2region.db_file_path   = null;
+ip2region.db_fd          = null;
+
+var totalBlocks         = 0;
+var firstIndexPtr       = 0;
+var lastIndexPtr        = 0;
+var superBlock          = new Buffer(8);
+
+var indexBlockLength    = 12;
+var totalHeaderLength   = 4096;
 
 
-function Ip2region(db_path)
+/**
+ * binary search
+ * */
+ip2region.binarySearch = function(ip)
 {
-    var fs   = require('fs');
+    if( typeof(ip) == 'string' ) 
-    var ipbase = [16777216, 65536, 256, 1]; // for ip2long
+        ip = ip2long(ip);
-    var db_file_path   = null;
+
-    var db_fd          = null;
+    // search
+    var low     = 0;
+    var mid     = 0;
+    var high    = totalBlocks;
+    var dataPos = 0;
+    var pos     = 0;
+    var sip     = 0;
+    var eip     = 0;
+    var indexBuffer = new Buffer(12);
+
+    // binary search
+    while( low <= high ) {
+        mid = ((low + high) >> 1);
+        pos = firstIndexPtr + mid * indexBlockLength;
+        fs.readSync(this.db_fd, indexBuffer, 0, indexBlockLength, pos);
+        sip = getLong(indexBuffer, 0);
+
+        //console.log( ' sip : ' + sip + ' eip : ' + eip );
+        if ( ip < sip) {
+            high = mid - 1;
+        } else {
+            eip = getLong(indexBuffer, 4);
+            if ( ip > eip ) {
+                low = mid + 1;
+            } else {
+                dataPos = getLong(indexBuffer, 8);
+                break;
+            }
+        }
+    }
+
+    // read data
+    if (dataPos == 0) return null;
+    var dataLen = ((dataPos >> 24) & 0xFF);
+    var dataPos = (dataPos & 0x00FFFFFF);
+    var dataBuffer = new Buffer(dataLen);
+
+    fs.readSync(this.db_fd, dataBuffer, 0, dataLen, dataPos);
+
+    var city_id = getLong(dataBuffer, 0);
+    var data    = dataBuffer.toString('utf8', 4, dataLen);
+
+    //console.log(city_id);
+    //console.log(data);
+
+    return { city: city_id, region: data };
+}
+
+
+/**
+ * btree search
+ * */
+ip2region.btreeSearch = function(ip) 
+{
+    return ip2long(ip);
+}
+
+
+/**
+ * convert ip to long (xxx.xxx.xxx.xxx to a integer)
+ * */
+function ip2long(ip)
+{
+    var val = 0;
+    ip.split('.').forEach(function(ele, i){
+        val += ipbase[i] * ele;
+    }); 
+
+    return val;
+}
+
+
+/**
+ * get long value from buffer with specified offset
+ * */
+function getLong(buffer, offset) 
+{
+    var val =  (   
+        (buffer[offset] & 0x000000FF) | 
+        ((buffer[offset + 1] <<  8) & 0x0000FF00) | 
+        ((buffer[offset + 2] << 16) & 0x00FF0000) |
+        ((buffer[offset + 3] << 24) & 0xFF000000)
+    );
+
+    // convert to unsigned int
+    if (val < 0) {
+        val = val >>> 0;
+    }
+    return val;
+}
+
+
+// api for create
+exports.create = function(db_path) {
 
     // db file check
     if (typeof(db_path) == "undefined" || fs.exists(db_path) ) {
         throw("[ip2region] db file not exists : " + db_path);
     }
     
-    db_file_path = db_path; 
+    ip2region.db_file_path = db_path; 
 
     try {
-        db_fd = fs.openSync(db_file_path, 'r');
+        ip2region.db_fd = fs.openSync(ip2region.db_file_path, 'r');
     } catch(e) {
-        throw("[ip2region] Can not open ip2region.db file , path : " + db_file_path);
+        throw("[ip2region] Can not open ip2region.db file , path : "
+                + ip2region.db_file_path);
     }
 
-    var totalBlocks     = 0;
+    // init basic search environment
-    var firstIndexPtr   = 0;
+    if (totalBlocks == 0) {
-    var lastIndexPtr    = 0;
+        fs.readSync(ip2region.db_fd, superBlock, 0, 8, 0);
-    var superBlock      = new Buffer(8);
+        firstIndexPtr = getLong(superBlock, 0);
-
+        lastIndexPtr  = getLong(superBlock, 4);
-    this.binarySearch = function(ip)
+        totalBlocks   = (lastIndexPtr - firstIndexPtr) 
-    {
+                            / indexBlockLength + 1;
-        if (typeof(ip) == 'string') ip = ip2long(ip);
-
-        // init basic search environment
-        if (totalBlocks == 0) {
-            fs.readSync(ip2r.db_fd, superBlock, 0, 8, 0);
-            firstIndexPtr = getLong(superBlock, 0);
-            lastIndexPtr  = getLong(superBlock, 4);
-        }
-
-        // search
-
-        return ip2long(ip);
     }
 
-
+    return ip2region;
-    this.btreeSearch = function(ip) 
-    {
-        return ip2long(ip);
-    }
-
-
-    /**
-     * convert ip to long (xxx.xxx.xxx.xxx to a integer)
-     * */
-    function ip2long(ip)
-    {
-        var val = 0;
-        ip.split('.').forEach(function(ele, i){
-            val += ipbase[i] * ele;
-        }); 
-
-        return val;
-    }
-
-
-    /**
-     * get long value from buffer with specified offset
-     * */
-    function getLong(buffer, offset) 
-    {
-        return  (   
-            (buffer[offset] & 0x000000FF) | 
-            ((buffer[offset + 1] <<  8) & 0x0000FF00) | 
-            ((buffer[offset + 2] << 16) & 0x00FF0000) |
-            ((buffer[offset + 3] << 24) & 0xFF000000)
-        );
-    }
 }
 
-module.exports = Ip2region;
+
+// api for destroy
+exports.destroy = function(ip2rObj){
+    ip2rObj.db_file_path = null;
+    fs.closeSync(ip2rObj.db_fd);
+}

binding/nodejs/test.js

@@ -3,6 +3,13 @@
  * */
 
 var Ip2region = require('./ip2region');
-var ip2region = new Ip2region('../../data/ip2region.db'); 
+//var ip2region = new Ip2region(); 
 
-console.log(ip2region.binarySearch("255.255.255.255"));
+// 1. create a ip2region object
+var ipObj = Ip2region.create('../../data/ip2region.db');
+
+// 2. use
+console.log(ipObj.binarySearch("120.24.78.68"));
+
+// 3. destroy
+Ip2region.destroy(ipObj);