Forwarded Headers parser

Direct parser use

using DamianH.Http.ForwardedHeaders;

var header = ForwardedHeaderParser.Parse(
    "for=192.0.2.60;proto=https;host=\"app.example.com:8443\"");
var first = header.Elements[0];
var host = first.Host;
var parameters = first.Parameters;

if (ForwardedHeaderParser.TryParse(
    new string?[] { "for=192.0.2.60", "for=10.0.0.10;proto=https" },
    out var parsed, out var error))
{
    var hopCount = parsed.Elements.Count;
}

if (ForwardedNodeIdentifier.TryParse("[2001:db8::1]:443", out var node))
{
    // A parsed node is not evidence that this address is a trusted proxy.
}

Parse and TryParse accept either one string or ordered IEnumerable<string?> field values. ForwardedHeader.Value retains the combined field text and Elements preserves wire order. Each immutable ForwardedElement has a case-insensitive Parameters dictionary and For, By, Host, Proto convenience properties. Parameter values are unquoted/unescaped; unknown extensions are retained.

The parser handles quoted separators, quoted-pair escapes, and empty list or semicolon slots; it rejects duplicate parameter names (including case variants and extensions). Syntax failures report an error position/reason; use TryParse for untrusted input without exceptions. Field parsing is not host/scheme validation or a trust decision. The separate node parser distinguishes concrete IP, unknown, and obfuscated identities and numeric/obfuscated ports; RFC-valid numeric port syntax is not necessarily a usable socket port.

The parser shares the middleware package's Microsoft.AspNetCore.App framework reference: even parser-only applications require the ASP.NET Core runtime. There is no public serializer in v1. See installation and proxy trust configuration.