add support for bypass proxy authentication for clients from current …

…LAN (#122)

ConfigFile.cs

@@ -217,6 +217,11 @@ static class ConfigFile
 		/// </summary>
 		public static string ContentDirectory = "./html";
 
+		/// <summary>
+		/// Bypass client authentication for local IPs
+		/// </summary>
+		public static bool OpenForLocalIPs = false;
+
 
 
 		/// <summary>

ConfigFileLoader.cs

@@ -370,6 +370,9 @@ public static void ProcessConfiguration()
 										case "AuthenticateRealm":
 											ConfigFile.AuthenticateRealm = Line.Value;
 											break;
+										case "OpenForLocalIPs":
+											ConfigFile.OpenForLocalIPs = ToBoolean(Line.Value);
+											break;
 										default:
 											Log.WriteLine(true, false, "Warning: Invalid authentication option at {0}.", Line.Location);
 											break;

HttpTransit.cs

@@ -100,6 +100,11 @@ public void ProcessTransit()
 							//PAC is always unprotected
 							break;
 						default:
+							if (ConfigFile.OpenForLocalIPs && IsLanIP(ClientRequest.RemoteEndPoint.Address))
+							{
+								Log.WriteLine(" Bypassed authorization of local client.");
+								break;
+							}
 							if (string.IsNullOrEmpty(ClientRequest.Headers["Proxy-Authorization"]))
 							{
 								Log.WriteLine(" Unauthorized client.");

Program.cs

@@ -976,6 +976,21 @@ from ipa in Netif.GetIPProperties().UnicastAddresses
 			return IPs.ToArray();
 		}
 
+		/// <summary>
+		/// Check if IP is inside LAN (behind router)
+		/// </summary>
+		/// <param name="address">The IP Address to check</param>
+		/// <returns><c>True</c> if it's local address or <c>False</c> if it's from Internet</returns>
+		public static bool IsLanIP(IPAddress address)
+		{
+			var ping = new Ping();
+			var rep = ping.Send(address, 100, new byte[] { 1 }, new PingOptions()
+			{
+				DontFragment = true,
+				Ttl = 1
+			});
+			return rep.Status != IPStatus.TtlExpired && rep.Status != IPStatus.TimedOut && rep.Status != IPStatus.TimeExceeded;
+		}
 
 		/// <summary>
 		/// Get this proxy server name and port