From 932a5d80b47f27d76105151fc178ecd05a6e443e Mon Sep 17 00:00:00 2001
From: lionsoul <chenxin619315@gmail.com>
Date: Tue, 2 Oct 2018 22:36:57 +0800
Subject: [PATCH] lua binding basic framework with memory search
 completed(tested)

---
 binding/lua/Ip2region.lua       | 187 ++++++++++++++++++++++++++++++++
 binding/lua/testSearch.lua      |   7 ++
 binding/php/Ip2Region.class.php |   1 -
 3 files changed, 194 insertions(+), 1 deletion(-)
 create mode 100644 binding/lua/Ip2region.lua
 create mode 100644 binding/lua/testSearch.lua

diff --git a/binding/lua/Ip2region.lua b/binding/lua/Ip2region.lua
new file mode 100644
index 0000000..66014a6
--- /dev/null
+++ b/binding/lua/Ip2region.lua
@@ -0,0 +1,187 @@
+--[[
+Ip2region lua binding
+
+@author chenxin<chenxin619315@gmail.com>
+@date   2018/10/02
+]]--
+
+require("bit32");
+
+local Ip2region = {
+    dbFileHandler = "",
+    HeaderSip = "", 
+    HeaderPtr = "",
+    headerLen = "",
+    firstIndexPtr = "",
+    lastIndexPtr = "", 
+    totalBlocks = "",
+    dbBinStr = "",
+    dbFile = ""
+};
+
+
+
+--[[
+internal function to get a integer from a binary string
+
+@param  dbBinStr
+@param  idx
+@return Integer
+]]--
+function getLong(bs, idx)
+    local a1 = string.byte(string.sub(bs, idx, idx));
+    local a2 = bit32.lshift(string.byte(string.sub(bs, idx+1, idx+1)),  8);
+    local a3 = bit32.lshift(string.byte(string.sub(bs, idx+2, idx+2)), 16);
+    local a4 = bit32.lshift(string.byte(string.sub(bs, idx+3, idx+3)), 24);
+
+    local val = bit32.bor(a1, a2);
+    val = bit32.bor(val, a3);
+    val = bit32.bor(val, a4);
+
+    return val;
+end
+
+
+--[[
+internal function to convert the string ip to a long value
+
+@param  ip
+@return Integer
+]]--
+function ip2long(ip)
+    local ini = 1;
+    local iip = 0;
+    local off = 24;
+    local int = 0;
+    while true do
+        local pos = string.find(ip, '.', ini, true);
+        if ( not pos or off <= 0 ) then
+            break;
+        end
+
+        int = tonumber(string.sub(ip, ini, pos - 1));
+        iip = bit32.bor(iip, bit32.lshift(int, off));
+        ini = pos + 1;
+        off = off - 8;
+    end
+
+    int = tonumber(string.sub(ip, ini));
+    iip = bit32.bor(iip, bit32.lshift(int, off));
+
+    return iip;
+end
+
+
+--[[
+internal function to get the whole content of a file
+
+@param  file
+@return String
+]]--
+function get_file_contents(file)
+    local fi = io.input(file);
+    if ( not fi ) then
+        return nil;
+    end
+
+    local str = io.read("*a");
+    io.close();
+    return str;
+end
+
+
+
+
+-- common constants
+local INDEX_BLOCK_LENGTH  = 12;
+local TOTAL_HEADER_LENGTH = 8192;
+
+function Ip2region:new(obj)
+    obj = obj or {};
+    setmetatable(obj, {__index = self});
+    return obj;
+end
+
+--[[
+all the db binary string will be loaded into memory
+then search the memory only and this will a lot faster than disk base search
+@Note: invoke it once before put it to public invoke could make it thread safe
+
+@param  ip
+@return table or nil for failed
+]]--
+function Ip2region:memorySearch(ip)
+    -- check and load the binary string for the first time
+    if ( self.dbBinStr == "" ) then
+        self.dbBinStr = get_file_contents(self.dbFile);
+        if ( not self.dbBinStr ) then
+            return nil;
+        end
+
+        self.firstIndexPtr = getLong(self.dbBinStr, 1);
+        self.lastIndexPtr  = getLong(self.dbBinStr, 5);
+        self.totalBlocks   = (self.lastIndexPtr - self.firstIndexPtr)/INDEX_BLOCK_LENGTH + 1;
+    end
+
+    if ( type(ip) == "string" ) then
+        ip = ip2long(ip);
+    end;
+
+    -- binary search to define the data
+    local l = 0;
+    local h = self.totalBlocks;
+    local dataPtr = 0;
+    while ( l <= h ) do
+        local m = math.floor((l + h) / 2);
+        local p = self.firstIndexPtr + m * INDEX_BLOCK_LENGTH;
+        local sip = getLong(self.dbBinStr, p + 1);
+        if ( ip < sip ) then
+            h = m - 1;
+        else
+            local eip = getLong(self.dbBinStr, p + 5);  -- 4 + 1
+            if ( ip > eip ) then
+                l = m + 1;
+            else
+                dataPtr = getLong(self.dbBinStr, p + 9); -- 8 + 1
+                break;
+            end
+        end
+    end
+
+    -- not matched just stop it here
+    if ( dataPtr == 0 ) then return nil end
+
+    -- get the data
+    local dataLen = bit32.band(bit32.rshift(dataPtr, 24), 0xFF);
+    dataPtr = bit32.band(dataPtr, 0x00FFFFFF);
+    local dptr = dataPtr + 5;   -- 4 + 1
+
+    return {
+        city_id = getLong(self.dbBinStr, dataPtr), 
+        region  = string.sub(self.dbBinStr, dptr, dptr + dataLen - 5)
+    };
+end
+
+
+--[[
+get the data block through the specified ip address 
+or long ip numeric with binary search algorithm
+
+@param  ip
+@return table or nil for failed
+]]--
+function Ip2region:binarySearch(ip)
+end
+
+
+--[[
+get the data block associated with the specified ip with b-tree search algorithm
+
+@param  ip
+@return table or nil for failed
+]]--
+function Ip2region:btreeSearch(ip)
+end
+
+
+return Ip2region;
diff --git a/binding/lua/testSearch.lua b/binding/lua/testSearch.lua
new file mode 100644
index 0000000..140c854
--- /dev/null
+++ b/binding/lua/testSearch.lua
@@ -0,0 +1,7 @@
+-- ip2region test lua script
+local cjson = require "cjson";
+local Ip2region = require "Ip2region";
+
+local searcher = Ip2region:new({dbFile = "../../data/ip2region.db"});
+local data = searcher:memorySearch("120.79.17.142");
+print(cjson.encode(data));
diff --git a/binding/php/Ip2Region.class.php b/binding/php/Ip2Region.class.php
index f15dc08..12bc0e0 100644
--- a/binding/php/Ip2Region.class.php
+++ b/binding/php/Ip2Region.class.php
@@ -358,4 +358,3 @@ class Ip2Region
         $this->HeaderPtr = NULL;
     }
 }
-?>