New DNS resolution function in PHP8.1

New DNS resolution function in PHP8.1

With the rapid development of the Internet, DNS (Domain Name System) resolution has become one of the common operations in Web development. In the PHP8.1 version, a new set of DNS resolution functions is introduced, allowing developers to perform DNS resolution operations more conveniently. This article will introduce the new DNS resolution functions in PHP8.1, and attach some code examples to help readers better understand and use these functions.

1. dns_ai_getaddrinfo()

The dns_ai_getaddrinfo() function is used to obtain IP address information based on the domain name. It is used as follows:

<?php
$hostname = "www.example.com";
$options = [
    'dns' => '8.8.8.8',
    'context' => null,
    'timeout' => 3,
    'hints' => 0
];

$result = dns_ai_getaddrinfo($hostname, $options);
if ($result !== false) {
    foreach ($result as $r) {
        echo $r['host'], ": ", $r['type'], " - ", $r['addr'], "
";
    }
} else {
    echo "Failed to resolve IP address for $hostname
";
}
?>

In the above code, we pass in the domain name to be resolved and a set of options, including the DNS server address, context, timeout and additional resolution prompts. If the parsing is successful, the function will return an array containing multiple IP address information; otherwise, it will return false.

2. dns_ai_gethostbyaddr()

dns_ai_gethostbyaddr() function is used to obtain the host name based on the IP address. It is used as follows:

<?php
$ip = "192.0.2.1";
$options = [
    'dns' => '8.8.8.8',
    'context' => null,
    'timeout' => 3,
    'hints' => 0
];

$result = dns_ai_gethostbyaddr($ip, $options);
if ($result !== false) {
    echo "Hostname for $ip: $result
";
} else {
    echo "Failed to resolve hostname for $ip
";
}
?>

In the above code, we pass in the IP address to be resolved and a set of options, including the DNS server address, context, timeout and additional resolution prompts. If the parsing is successful, the function will return a string, which is the host name; otherwise, it will return false.

3. dns_ai_getaddrbyaddr()

The dns_ai_getaddrbyaddr() function is the opposite of the dns_ai_gethostbyaddr() function and is used to obtain the IP address based on the host name. It is used as follows:

<?php
$hostname = "www.example.com";
$options = [
    'dns' => '8.8.8.8',
    'context' => null,
    'timeout' => 3,
    'hints' => 0
];

$result = dns_ai_getaddrbyaddr($hostname, $options);
if ($result !== false) {
    echo "IP address for $hostname: $result
";
} else {
    echo "Failed to resolve IP address for $hostname
";
}
?>

In the above code, we pass in the host name to be resolved and a set of options, including the DNS server address, context, timeout and additional resolution prompts. If the parsing is successful, the function will return a string, which is the IP address; otherwise, it will return false.

Summary:

The new DNS resolution function in PHP8.1 provides developers with a more powerful resolution tool, making it easier to process domain names and IP addresses. We can obtain IP address information based on the domain name through the dns_ai_getaddrinfo() function, obtain the host name based on the IP address through the dns_ai_gethostbyaddr() function, and obtain the IP address based on the host name through the dns_ai_getaddrbyaddr() function. Through these functions, we can easily perform DNS resolution operations, providing more convenience for our Web development.

Please note that these functions are only available in PHP8.1 and above. If you are still using an old version of PHP, it is recommended to upgrade to PHP8.1 as soon as possible to enjoy the convenience brought by these new features.

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