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using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Net;
using System.Net.Sockets;
using System.Text.RegularExpressions;
namespace MediaBrowser.Common.Net
{
/// <summary>
/// Defines the <see cref="NetworkExtensions" />.
/// </summary>
public static class NetworkExtensions
{
/// <summary>
/// Returns true if the IPAddress contains an IP6 Local link address.
/// </summary>
/// <param name="address">IPAddress object to check.</param>
/// <returns>True if it is a local link address.</returns>
/// <remarks>
/// See https://stackoverflow.com/questions/6459928/explain-the-instance-properties-of-system-net-ipaddress
/// it appears that the IPAddress.IsIPv6LinkLocal is out of date.
/// </remarks>
public static bool IsIPv6LinkLocal(IPAddress address)
{
if (address == null)
{
throw new ArgumentNullException(nameof(address));
}
if (address.IsIPv4MappedToIPv6)
{
address = address.MapToIPv4();
}
if (address.AddressFamily != AddressFamily.InterNetworkV6)
{
return false;
}
// GetAddressBytes
Span<byte> octet = stackalloc byte[16];
address.TryWriteBytes(octet, out _);
uint word = (uint)(octet[0] << 8) + octet[1];
return word >= 0xfe80 && word <= 0xfebf; // fe80::/10 :Local link.
}
/// <summary>
/// Convert a subnet mask in CIDR notation to a dotted decimal string value. IPv4 only.
/// </summary>
/// <param name="cidr">Subnet mask in CIDR notation.</param>
/// <param name="family">IPv4 or IPv6 family.</param>
/// <returns>String value of the subnet mask in dotted decimal notation.</returns>
public static IPAddress CidrToMask(byte cidr, AddressFamily family)
{
uint addr = 0xFFFFFFFF << (family == AddressFamily.InterNetwork ? 32 : 128 - cidr);
addr = ((addr & 0xff000000) >> 24)
| ((addr & 0x00ff0000) >> 8)
| ((addr & 0x0000ff00) << 8)
| ((addr & 0x000000ff) << 24);
return new IPAddress(addr);
}
/// <summary>
/// Convert a subnet mask to a CIDR. IPv4 only.
/// https://stackoverflow.com/questions/36954345/get-cidr-from-netmask.
/// </summary>
/// <param name="mask">Subnet mask.</param>
/// <returns>Byte CIDR representing the mask.</returns>
public static byte MaskToCidr(IPAddress mask)
{
if (mask == null)
{
throw new ArgumentNullException(nameof(mask));
}
byte cidrnet = 0;
if (!mask.Equals(IPAddress.Any))
{
// GetAddressBytes
Span<byte> bytes = stackalloc byte[mask.AddressFamily == AddressFamily.InterNetwork ? 4 : 16];
mask.TryWriteBytes(bytes, out _);
var zeroed = false;
for (var i = 0; i < bytes.Length; i++)
{
for (int v = bytes[i]; (v & 0xFF) != 0; v <<= 1)
{
if (zeroed)
{
// Invalid netmask.
return (byte)~cidrnet;
}
if ((v & 0x80) == 0)
{
zeroed = true;
}
else
{
cidrnet++;
}
}
}
}
return cidrnet;
}
/// <summary>
/// Converts an IPAddress into a string.
/// Ipv6 addresses are returned in [ ], with their scope removed.
/// </summary>
/// <param name="address">Address to convert.</param>
/// <returns>URI safe conversion of the address.</returns>
public static string FormatIpString(IPAddress? address)
{
if (address == null)
{
return string.Empty;
}
var str = address.ToString();
if (address.AddressFamily == AddressFamily.InterNetworkV6)
{
int i = str.IndexOf('%', StringComparison.Ordinal);
if (i != -1)
{
str = str.Substring(0, i);
}
return $"[{str}]";
}
return str;
}
/// <summary>
/// Attempts to parse a host string.
/// </summary>
/// <param name="host">Host name to parse.</param>
/// <param name="addresses">Object representing the string, if it has successfully been parsed.</param>
/// <param name="isIpv4Enabled"><c>true</c> if IPv4 is enabled.</param>
/// <param name="isIpv6Enabled"><c>true</c> if IPv6 is enabled.</param>
/// <returns><c>true</c> if the parsing is successful, <c>false</c> if not.</returns>
public static bool TryParseHost(string host, [NotNullWhen(true)] out IPAddress[] addresses, bool isIpv4Enabled = true, bool isIpv6Enabled = false)
{
if (string.IsNullOrWhiteSpace(host))
{
addresses = Array.Empty<IPAddress>();
return false;
}
host = host.Trim();
// See if it's an IPv6 with port address e.g. [::1] or [::1]:120.
if (host[0] == '[')
{
int i = host.IndexOf(']', StringComparison.Ordinal);
if (i != -1)
{
return TryParseHost(host.Remove(i)[1..], out addresses);
}
addresses = Array.Empty<IPAddress>();
return false;
}
var hosts = host.Split(':');
if (hosts.Length <= 2)
{
// Use regular expression as CheckHostName isn't RFC5892 compliant.
// Modified from gSkinner's expression at https://stackoverflow.com/questions/11809631/fully-qualified-domain-name-validation
string pattern = @"(?im)^(?!:\/\/)(?=.{1,255}$)((.{1,63}\.){0,127}(?![0-9]*$)[a-z0-9-]+\.?)(:(\d){1,5}){0,1}$";
// Is hostname or hostname:port
if (Regex.IsMatch(hosts[0], pattern))
{
try
{
addresses = Dns.GetHostAddresses(hosts[0]);
return true;
}
catch (SocketException)
{
// Log and then ignore socket errors, as the result value will just be an empty array.
Console.WriteLine("GetHostAddresses failed.");
}
}
// Is an IP4 or IP4:port
host = hosts[0].Split('/')[0];
if (IPAddress.TryParse(host, out var address))
{
if (((address.AddressFamily == AddressFamily.InterNetwork) && (!isIpv4Enabled && isIpv6Enabled)) ||
((address.AddressFamily == AddressFamily.InterNetworkV6) && (isIpv4Enabled && !isIpv6Enabled)))
{
addresses = Array.Empty<IPAddress>();
return false;
}
addresses = new[] { address };
// Host name is an ip4 address, so fake resolve.
return true;
}
}
else if (hosts.Length <= 9 && IPAddress.TryParse(host.Split('/')[0], out var address)) // 8 octets + port
{
addresses = new[] { address };
return true;
}
addresses = Array.Empty<IPAddress>();
return false;
}
}
}
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