How to develop a virtual domain name system_PHP tutorial

Everyone feels very convenient when using abbreviated domain names such as yourname.yeah.net. Many people are thinking: If only I could enable my own server to implement abbreviated domain names. Actually it's not complicated. After reading this article, you can also create an abbreviated domain name system.

The key technology of the abbreviated domain name system is to realize the redirection of Web pages (Redirectory). In essence, abbreviated domain name systems and virtual machine systems are completely different. There is a one-to-one correspondence between the virtual domain name and IP of the virtual machine. The abbreviated domain name system does not require one-to-one mapping of domain names and IPs. In other words, it does not require complex domain name resolution mechanisms and virtual machines to complete at all. What it does is when you request yourname.somedomain, redirect your browser to the place where you originally stored the Html page.

In order to explain more completely, the following legend is:

The source program I provide is the running environment: Apache1.3.6 Web server + PHP3 language under RedHat 5.1 Linux. Before writing the program, we first need to set up our server. First, let the Apache server support php3. Go to ftp.redhat.com to download mod_php-2.0.1-9.i386.rpm. After installation, modify the /etc/httpd/conf/http.conf file and remove the # comment in front of the #LoadModule php3_module sentence, also in /etc Remove the comment number in front of #AddType application/x-httpd-php3 .php3 in the /httpd/conf/srm.conf file, and add index.php3 after the DirectoryIndex item. Restart Apache Server. At this time, the server supports standard php3 language script files and can use index.php3 as the default home page.
Set up the DNS server so that it can resolve pan-domain names. DNS resolution in general Unix and Linux systems is completed by the Bind daemon. The configuration files of Bind4 and Bind8 are /etc/named.boot and name.conf respectively. Modify them according to your system during configuration. Set the Bind configuration file /etc/named.boot, add the sentence "primary domain.com db.domain" to it, and add a new domain record. Add to /etc/name.conf:

zone "domain.com" {
type master;
file "db.domain";
};
in /var Create a new main domain record file db.domain in /name/, its format is:
N SOA dns.domain.com root.domain.com (
199811291 ; Serial
28800 ; refresh
7200 ; retry
604800 ;expire
86400) ;minimum
dns
MX 10 dns.domain.com. 5.135.50 
　* A 202.115.135.50
The key is the last sentence, that is, all unmarked Hostnames in the entire domain may point to the same IP. Execute /usr/sbin/ndc reload to reload the domain name database. Test it. At this time, you should ping any host in the domain (except those that have been marked), and all point to the specified IP. Then the DNS server setting is completed.


The last step is to compile the PHP3 script. We have just explained the entire principle in detail in the figure, so it is not difficult to write a redirection program.


Let’s take a look at a complete HTTP header sent by IE5.0:


Accept: application/vnd.ms-excel, application/msword, application/ vnd.ms-powerpoint, Image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, */*
Accept-Encoding: gzip, deflate
Accept-Language: zh-cn
Connection: Keep-Alive
Host: ww.yahoo.com
User-Agent: Mozilla/4.0 (compatible; MSIE 5.0b1; Windows 98)
We need to remove the Host information from the entire HTTP header. Then take out the first part "www" in the form of http://www.jj.jx.cn/www.xxx.xxx/default.htm, that is, HostName (that is, the name registered by the user) separately, as a redirect retrieval Keywords.


After retrieving the user's registered URL information, we send a redirection command "Localtion: http://www.jj.jx.cn/somewhere/sample.html" to the user's browser. Redirect the user to the specified page.


In PHP3, there is the function GetAllHeader() to obtain the HTTP header information sent by the browser. We mainly need to use this function to complete the entire program.


The source program is attached at the end. Since it is only experimental, the database is not used when querying user information. If the entire system is to be put into practical use, it must be connected to the database, otherwise the query The process of user information will be very long, greatly affecting efficiency, and the management of user data will be inconvenient. (Due to space limitations, the writing record program required for registration and management is not given, please add it yourself)


In the source program, all user information is recorded in the user.dat file under the data subdirectory. .其格式为：  


　　username:  


　　http://octopus.cdit.edu.cn/~qap213/index.html  


　　附PHP3源程序：  


　　

　　//Get HTTP's Header and parse it//  


　　$headers = getallheaders();  


　　while (list($header, $value) = each($headers)) {  


　　if($header=="Host"){$username= strtok($value,".");}}  


　　//Jump out the Banner's Window//  


　　echo '';  


　  

　　// seek the user information from the recorded file//  


　　if(!$usrinfo=file("data/user.dat")){echo "Open Data File Error!!";}  


　　$url="http://";  


　　for($i=0;$i

　　if(strtok($usrinfo[$i],":")==$username){  


　　$url=$usrinfo[$i+1];  


　　}  


　　if($url=="http://"){echo "not found the uesrname of Data!";}  


　　else{  


　　echo '';}  


　　?>  

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