Detailed explanation of how to implement dns domain name query in php (picture and text)-PHP Tutorial-php.cn

Detailed explanation of how to implement dns domain name query in php (picture and text)

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Release： 2016-07-25 08:57:02

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This article introduces a code that uses PHP to query dns domain name information. Friends in need can refer to it.

In PHP domain name related operations, two functions are generally used, they are: gethostbyname() and gethostbyaddr().

1. IP address query The gethostbyname() function can be used to find the IP address of a given domain name. gethostbyname() returns a pointer to a hostent structure containing host name and address information corresponding to the given hostname.

string gethostbyname(string hostname) Parameters: host name, http:// is not required, for example: bbs.it-home.org. This function can return the IP address (IP Address) of a certain machine name (Domain Name). If the execution fails, the original machine name is returned.

Second, domain name query

gethostbyaddr returns the machine name.

Syntax: string gethostbyaddr(string ip_address);

Return value: string

Function type: Network system

Content description

This function can return the machine name (Domain Name) of a certain IP address. If the execution fails, the original IP address is returned.

Three, examples The following code implements domain name IP address and domain name query, which is a good example.

<?php 
// dnslookupip.php - DNS/IP Address Lookup 

// Page title 
$pagetitle        = 'PHP域名查询程序'; 

// Prompts 
$prompt_ip        = 'IP Address'; 
$prompt_dn        = 'Domain Name'; 

// Messages 
$lookupfail        = '<span style="color:red;">* lookup failed *</span>'; 

// Get submitted host/domain name 
$dn    = isset($_REQUEST['dn']) ? $_REQUEST['dn'] : ''; 
if ($dn == $prompt_dn) 
{ 
    $dn = ''; 
} 

// Get submitted ip address 
$ip    = isset($_REQUEST['ip']) ? $_REQUEST['ip'] : ''; 
if ($ip == $prompt_ip) 
{ 
    $ip = ''; 
} 

// Check if host/domain name specified 
if ($dn) 
{ 
    // Domain name specified; IP address lookup request 
    if ($dn == 'me') 
    { 
        $ip = $_SERVER['REMOTE_ADDR']; 
    } 
    else 
    { 
        // Lookup IP address by domain/host name 
        $ip = @gethostbyname($dn); 
        if ($ip == $dn) 
        { 
            $ip = $lookupfail; 
        } 
    } 
    $message = $prompt_dn.' '.$dn.' :: '.$prompt_ip.' '.$ip; 
} 
// Check if IP address specified 
else if ($ip) 
{ 
    // Lookup domain/host name by IP address     
    $dn = @gethostbyaddr($ip); 
    // Check lookup 
    if ($dn == $ip) 
    { 
        // IP address invalid or domain name not found 
        $dn = $lookupfail; 
    } 
    $message = $prompt_ip.' '.$ip.' :: '.$prompt_dn.' '.$dn; 
} 
else 
{ 
    $message = $prompt_dn.' '.$_SERVER['HTTP_HOST'] 
        .' :: '.$prompt_ip.' '.$_SERVER['SERVER_ADDR']; 
} 
?> 
<html> 
<head> 
<title><?php echo $pagetitle;?></title> 
</head> 
<body style="background-color:#cfcfcf;font-family:Arial;sans-serif;font-size:12px;"> 
<h3 style="font-size:13px;margin-bottom:0px;"><?php echo $pagetitle;?></h3> 
<hr /> 
<p style="margin-top:4px;margin-bottom:4px;font-size:12px;"> 
<?php echo $message;?> 
</p> 
<form style="margin-top:4px;margin-bottom:4px;"> 
<input style="font-size:12px;" type="text" name="dn" 
    value="<?php echo $prompt_dn;?>" size="30" /> 
<input style="font-size:12px;" type="text" name="ip"  
    value="<?php echo $prompt_ip;?>" size="15" />  
<input style="font-size:12px;" type="submit" value="Lookup" /> 
</form> 
<hr /> 
<p style="margin:0px;font-size:9px;color:#666666;"> 
Copyright &#169; 2003-<?php echo date('Y');?> 
 by 程序员之家，欢迎您! 
</p> 
</body> 
</html>

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