// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.HttpOverrides;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Options;

namespace Microsoft.AspNetCore;

internal sealed class ForwardedHeadersOptionsSetup : IConfigureOptions<ForwardedHeadersOptions>
{
    private readonly IConfiguration _configuration;

    public ForwardedHeadersOptionsSetup(IConfiguration configuration)
    {
        _configuration = configuration;
    }

    public void Configure(ForwardedHeadersOptions options)
    {
        if (!string.Equals("true", _configuration["ForwardedHeaders_Enabled"], StringComparison.OrdinalIgnoreCase))
        {
            return;
        }

        options.ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto;
        // Only loopback proxies are allowed by default. Clear that restriction because forwarders are
        // being enabled by explicit configuration.
        options.KnownIPNetworks.Clear();
        options.KnownProxies.Clear();
    }
}