43 lines
2.3 KiB
C#
43 lines
2.3 KiB
C#
using System.Net;
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namespace Swan.Net
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{
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/// <summary>
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/// Provides utility methods to work with the <see cref="IPAddress"/> class.
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/// </summary>
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public static class IPAddressUtility
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{
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/// <summary>
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/// <para>Tries to convert the string representation of an IP address
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/// into an instance of <see cref="IPAddress"/></para>
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/// <para>This method works the same way as <see cref="IPAddress.TryParse"/>,
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/// with the exception that it will not recognize a decimal number alone
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/// as an IPv4 address.</para>
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/// </summary>
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/// <param name="str">The string to be converted.</param>
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/// <param name="address">When this method returns <see langword="true"/>,
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/// an instance of <see cref="IPAddress"/> representing the same address
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/// as <paramref name="str"/>.</param>
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/// <returns><see langword="true"/> if the conversion was successful;
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/// otherwise, <see langword="false"/>.</returns>
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public static bool TryParse(string? str, out IPAddress address)
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{
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// https://docs.microsoft.com/en-us/dotnet/api/system.net.ipaddress.tryparse
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// "Note that this method accepts as valid an ipString value that can be parsed as an Int64,
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// and then treats that Int64 as the long value of an IP address in network byte order,
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// similar to the way that the IPAddress constructor does.
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// This means that this method returns true if the Int64 is parsed successfully,
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// even if it represents an address that's not a valid IP address.
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// For example, if str is "1", this method returns true even though "1" (or 0.0.0.1)
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// is not a valid IP address and you might expect this method to return false.
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// Fixing this bug would break existing apps, so the current behavior will not be changed.
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// Your code can avoid this behavior by ensuring that it only uses this method
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// to parse IP addresses in dotted-decimal format."
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// ---
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// Thus, if it parses as an Int64, let's just refuse it.
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// One-part IPv4 addresses be darned.
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address = IPAddress.None;
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return !long.TryParse(str, out _) && IPAddress.TryParse(str, out address);
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}
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}
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} |