DtDNS: PHP cURL 1

DtDNS and automatic update

Introduction

On the previous page I explained why you should never enable external includes in php.ini there is a safer way to download external pages and that is to use cURL.

Uniform Server 5.0-Nano has cURL enabled by default hence you can start using it straightaway. This page looks at extracting your current IP address from one of the pages downloaded see previous page for page links.

Example Code

This script is based on a template taken from the cURL tutorial found on this page.

Page downloaded is captured as a text string and saved in variable $buffer. This isolates any potenial harfull code.

Extracting the IP address is performed using a regex since we are specifically targeting information we want and discarding any other page content means any harmful code will never be run.

<?php
$ch=curl_init();
curl_setopt($ch,CURLOPT_URL,'http://myip.dtdns.com');
curl_setopt($ch,CURLOPT_CONNECTTIMEOUT,10);
curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
$buffer = curl_exec($ch);
curl_close($ch);

if (empty($buffer)){
  // Need to add code and recover from this
}

else{
  // Extract IP address 
 if(preg_match("/(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})/", $buffer, $ipmatch)){  
    $ip = $ipmatch[0]; // Save IP to variable
 }
}
    print $ip;  // Test code 
?>

Initialize Curl and save memory location in variable $ch
Set the Curl URL option to the URL we wish to work with
Set the Curl TIMEOUT option to 10 Seconds. If page fails to load give-up after 10 seconds
Set RETURNTRANSFER to 1. This forces the output of curl_exec() to be a string and not to reserve page.
Run Curl curl_exec(), downloads page from external server converts it to a string which is saved in variable $buffer
Close Curl
Check buffer empty will need to do something in the final script if empty
Its not empty use preg_match to extract matched pattern, save in array $ipmatch
Save first element to variable $ip
Print to confirm.

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Test 1 - Server

The script will run on a server, perform the following test:

Create a new folder C:\dtdns_test
Extract a copy of 5-Nano to this folder.
Create a new text file in folder C:\dtdns_test\UniServer\www and name it dtdns_test_1.php add the following content

<?php
$ch=curl_init();
curl_setopt($ch,CURLOPT_URL,'http://myip.dtdns.com');
curl_setopt($ch,CURLOPT_CONNECTTIMEOUT,10);
curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
$buffer = curl_exec($ch);
curl_close($ch);

if (empty($buffer)){
  // Need to add code and recover from this
}

else{
  // Extract IP address 
 if(preg_match("/(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})/", $buffer, $ipmatch)){  
    $ip = $ipmatch[0]; // Save IP to variable
 }
}
    print $ip;  // Test code 
?>

Run Test 1:

Run servers
Type http://localhost/dtdns_test_1.php into your browser
Result: Returns your currentIP address for example

179.79.934.216

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Test 2 - PHP CLI

We require the script to run in PHP cli mode.

Create a new folder C:\dtdns_test\UniServer\plugins\dtdns_updater
Copy file C:\dtdns_test\UniServer\www\dtdns_test_1.php to the above folder.
Inside folder dtdns_updater create a new text file Run_dtdns_test_1.bat with the folowing content:

Run_dtdns_test_1.bat

COLOR B0
@echo off
cls

rem ### working directory current folder 
pushd %~dp0

..\..\usr\local\php\php.exe  dtdns_test_1.php

rem ### restore original working directory
pause
popd
EXIT

Run Test 2:

Close servers
Double click on Run_dtdns_test_1.bat
Result: Returns your current IP address for example

179.79.934.216Press any key to continue . . .

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Summary

I have shown how easy Curl is to use and how to obtain your current IP address. The code can be used in either server or CLI mode.

Its only part of a solution we need to access DtDNS update page by providing an ID and password over a secure connection. Again Curl makes this easy see next page.

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