Detects Proxy settings URI, UserName, Password

ProxyHelper.cs

using System;
using System.Net;

namespace Helpers
{
    /// <summary>
    /// Checks proxy settings for given URI.
    /// </summary>
    internal class ProxyHelper
    {
        private Uri proxyAddress;
        /// <summary>
        /// Indicates weither proxy is discovered for given URI
        /// </summary>
        public bool IsBypassed { get; private set; } = true;

        /// <summary>
        /// Returns proxy address in case if proxy server was discovered
        /// Throws exception if <see cref="IsBypassed"/> set to false.
        /// </summary>
        public string ProxyAddress => proxyAddress.AbsoluteUri;

        /// <summary>
        /// Gets host of proxy server.
        /// Throws exception if <see cref="IsBypassed"/> set to false.
        /// </summary>
        public string Host => proxyAddress.Host;
        /// <summary>
        /// Gets port of proxy server.
        /// Throws exception if <see cref="IsBypassed"/> set to false.
        /// </summary>
        public int Port => proxyAddress.Port;

        /// <summary>
        /// Returns User name form credentials cache, if any
        /// </summary>
        public string UserName { get; set; } = string.Empty;

        /// <summary>
        /// Returns User password form credentials cache, if any
        /// </summary>
        public string Password { get; private set; } = string.Empty;

        /// <summary>
        /// Extracts proxy and credential info from network configuration
        /// </summary>
        /// <param name="address"></param>
        public ProxyHelper(Uri address)
        {
            var normalizedAddress = GetNormalizedUri(address);

            var proxy = WebRequest.GetSystemWebProxy();
            proxy.Credentials = CredentialCache.DefaultNetworkCredentials;

            IsBypassed = proxy.IsBypassed(normalizedAddress);

            if (!IsBypassed)
            {
                proxyAddress = proxy.GetProxy(normalizedAddress);
                var defCreds = CredentialCache.DefaultCredentials as NetworkCredential;

                if (defCreds == null)
                {
                    return;
                }

                UserName = string.IsNullOrEmpty(defCreds.Domain) ? defCreds.UserName : $"{defCreds.Domain}\\{defCreds.UserName}";
                Password = defCreds.Password;
            }
        }

        /// <summary>
        /// Normalizes URI   
        /// we get wss:// (or ws://) scheme that is not all proxies handle correctly. 
        /// For better autodiscovering replace wss:// to https:// (ws:// to http:// accordingly)
        /// </summary>
        /// <param name="wsAddress"></param>
        /// <returns></returns>
        public static Uri GetNormalizedUri(Uri wsAddress)
        {
            return new UriBuilder(wsAddress.Scheme == "wss" ? Uri.UriSchemeHttps : Uri.UriSchemeHttp, wsAddress.DnsSafeHost, wsAddress.Port).Uri;
        }
    }
}