ForwardedHeadersOptions.cs

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using Microsoft.AspNetCore.HttpOverrides;

namespace Microsoft.AspNetCore.Builder
{
    public class ForwardedHeadersOptions
    {
        private const string UseRelaxedHeaderValidationSwitch = "Switch.Microsoft.AspNetCore.HttpOverrides.UseRelaxedHeaderValidation";
        private static readonly bool GlobalUseRelaxedHeaderValidation;

        static ForwardedHeadersOptions()
        {
#if NET451
            var value = System.Configuration.ConfigurationManager.AppSettings.GetValues(UseRelaxedHeaderValidationSwitch)?.FirstOrDefault();
            var isEnabled = false;
            if (bool.TryParse(value, out isEnabled))
            {
                GlobalUseRelaxedHeaderValidation = isEnabled;
            }
#else
            AppContext.TryGetSwitch(UseRelaxedHeaderValidationSwitch, out GlobalUseRelaxedHeaderValidation);
#endif
        }

        internal bool UseRelaxedHeaderValidation { get; set; } = GlobalUseRelaxedHeaderValidation;

        /// <summary>
        /// Use this header instead of <see cref="ForwardedHeadersDefaults.XForwardedForHeaderName"/>
        /// </summary>
        /// <seealso cref="Microsoft.AspNetCore.HttpOverrides.ForwardedHeadersDefaults"/>
        public string ForwardedForHeaderName { get; set; } = ForwardedHeadersDefaults.XForwardedForHeaderName;

        /// <summary>
        /// Use this header instead of <see cref="ForwardedHeadersDefaults.XForwardedHostHeaderName"/>
        /// </summary>
        /// <seealso cref="ForwardedHeadersDefaults"/>
        public string ForwardedHostHeaderName { get; set; } = ForwardedHeadersDefaults.XForwardedHostHeaderName;

        /// <summary>
        /// Use this header instead of <see cref="ForwardedHeadersDefaults.XForwardedProtoHeaderName"/>
        /// </summary>
        /// <seealso cref="ForwardedHeadersDefaults"/>
        public string ForwardedProtoHeaderName { get; set; } = ForwardedHeadersDefaults.XForwardedProtoHeaderName;

        /// <summary>
        /// Use this header instead of <see cref="ForwardedHeadersDefaults.XOriginalForHeaderName"/>
        /// </summary>
        /// <seealso cref="ForwardedHeadersDefaults"/>
        public string OriginalForHeaderName { get; set; } = ForwardedHeadersDefaults.XOriginalForHeaderName;

        /// <summary>
        /// Use this header instead of <see cref="ForwardedHeadersDefaults.XOriginalHostHeaderName"/>
        /// </summary>
        /// <seealso cref="ForwardedHeadersDefaults"/>
        public string OriginalHostHeaderName { get; set; } = ForwardedHeadersDefaults.XOriginalHostHeaderName;

        /// <summary>
        /// Use this header instead of <see cref="ForwardedHeadersDefaults.XOriginalProtoHeaderName"/>
        /// </summary>
        /// <seealso cref="ForwardedHeadersDefaults"/>
        public string OriginalProtoHeaderName { get; set; } = ForwardedHeadersDefaults.XOriginalProtoHeaderName;

        /// <summary>
        /// Identifies which forwarders should be processed.
        /// </summary>
        public ForwardedHeaders ForwardedHeaders { get; set; }

        /// <summary>
        /// Limits the number of entries in the headers that will be processed. The default value is 1.
        /// Set to null to disable the limit, but this should only be done if
        /// KnownProxies or KnownNetworks are configured.
        /// </summary>
        public int? ForwardLimit { get; set; } = 1;

        /// <summary>
        /// Addresses of known proxies to accept forwarded headers from.
        /// </summary>
        public IList<IPAddress> KnownProxies { get; } = new List<IPAddress>() { IPAddress.IPv6Loopback };

        /// <summary>
        /// Address ranges of known proxies to accept forwarded headers from.
        /// </summary>
        public IList<IPNetwork> KnownNetworks { get; } = new List<IPNetwork>() { new IPNetwork(IPAddress.Loopback, 8) };

        /// <summary>
        /// Require the number of header values to be in sync between the different headers being processed.
        /// The default is 'true'.
        /// </summary>
        public bool RequireHeaderSymmetry { get; set; } = true;
    }
}