SocketOptionMappingGenerator

SocketOptionMappingGenerator.cs

using System.Net.Sockets;
using System.Text;

// Relevant option names and values taken from Windows headers.
(string Name, int Value)[] ipOptions = [
    ("IP_TOS", 3),
    ("IP_TTL", 4),
];

(string Name, int Value)[] ipv6Options = [
    ("IPV6_PROTECTION_LEVEL", 23),
    ("IPV6_V6ONLY", 27),
];

(string Name, int Value)[] tcpOptions = [
    ("TCP_NODELAY", 0x0001),
    ("TCP_EXPEDITED_1122", 0x0002),
    ("TCP_KEEPALIVE", 3),
    ("TCP_FASTOPEN", 15),
    ("TCP_KEEPCNT", 16),
    ("TCP_KEEPINTVL", 17),
];

(string Name, int Value)[] soOptions = [
    ("SO_DEBUG", 0x0001),
    ("SO_ACCEPTCONN", 0x0002),
    ("SO_REUSEADDR", 0x0004),
    ("SO_KEEPALIVE", 0x0008),
    ("SO_DONTROUTE", 0x0010),
    //("SO_BROADCAST", 0x0020),
    ("SO_USELOOPBACK", 0x0040),
    ("SO_LINGER", 0x0080),
    ("SO_OOBINLINE", 0x0100),
    ("SO_DONTLINGER", ~0x0080),
    ("SO_EXCLUSIVEADDRUSE", ~0x0004),
    ("SO_SNDBUF", 0x1001),
    ("SO_RCVBUF", 0x1002),
    ("SO_SNDLOWAT", 0x1003),
    ("SO_RCVLOWAT", 0x1004),
    ("SO_SNDTIMEO", 0x1005),
    ("SO_RCVTIMEO", 0x1006),
];

var allOptions = ipOptions.Union(ipv6Options).Union(tcpOptions).Union(soOptions);
int[] relevantOptionValues = allOptions.Select(o => o.Value).Distinct().ToArray();
string[] dotnetOptionNames = Enum.GetNames<SocketOptionName>();
int[] dotnetOptionValues = (int[])Enum.GetValuesAsUnderlyingType<SocketOptionName>();

StringBuilder bld = new StringBuilder().AppendLine($@"
private enum TrackableSocketOptions
{{
    None = 0,
    {string.Join($",{Environment.NewLine}    ", allOptions.Select(o => o.Name))}
}}

internal const int TrackableOptionCount => (int)TrackableSocketOptions.{allOptions.Last().Name};

private static TrackableSocketOptions ToTrackableSocketOptions(SocketOptionName name, SocketOptionLevel level)
    => ((int)name, level) switch
    {{");

AppendForwardMappingExpressions(ipOptions, SocketOptionLevel.IP);
AppendForwardMappingExpressions(ipv6Options, SocketOptionLevel.IPv6);
AppendForwardMappingExpressions(tcpOptions, SocketOptionLevel.Tcp);
AppendForwardMappingExpressions(soOptions, SocketOptionLevel.Socket);

bld.AppendLine(@"
        _ => TrackableSocketOptions.None
    };");

bld.AppendLine(@"
private static (SocketOptionName, SocketOptionLevel) ToSocketOptions(TrackableSocketOptions options) =>
    options switch
    {");

AppendBackwardMappingExpressions(ipOptions, SocketOptionLevel.IP);
AppendBackwardMappingExpressions(ipv6Options, SocketOptionLevel.IPv6);
AppendBackwardMappingExpressions(tcpOptions, SocketOptionLevel.Tcp);
AppendBackwardMappingExpressions(soOptions, SocketOptionLevel.Socket);
bld.AppendLine(@"
        _ => default
    };");

void AppendForwardMappingExpressions((string Name, int Value)[] options, SocketOptionLevel level)
{
    foreach ((string name, int value) in options)
        bld.AppendLine($"        ({value}, SocketOptionLevel.{level}) => TrackableSocketOptions.{name},");
}

void AppendBackwardMappingExpressions((string Name, int Value)[] options, SocketOptionLevel level)
{
    foreach ((string name, int value) in options)
        bld.AppendLine($"        TrackableSocketOptions.{name} => ((SocketOptionName){(value < 0 ? $"({value})" : $"{value}")}, SocketOptionLevel.{level}),");
}

Console.WriteLine(bld);