option for zenserver - `--http-forceloopback` (#516)

* New option for zenserver - `--http-forceloopback` which forces opening of the server http server using loopback (local) connection (UE-199776)
* add fallback to local connection for asio if we get access denied on public port

1 files changed, 18 insertions, 9 deletions

diff --git a/src/zenhttp/servers/httpsys.cpp b/src/zenhttp/servers/httpsys.cpp
index 4eeab6662..0b11d396b 100644
--- a/src/zenhttp/servers/httpsys.cpp
+++ b/src/zenhttp/servers/httpsys.cpp
@@ -1003,18 +1003,27 @@ HttpSysServer::InitializeServer(int BasePort)
 
 	int EffectivePort = BasePort;
 
-	Result = HttpAddUrlToUrlGroup(m_HttpUrlGroupId, WildcardUrlPath.c_str(), HTTP_URL_CONTEXT(0), 0);
-
-	if ((Result == ERROR_SHARING_VIOLATION) && AllowPortProbing)
+	if (m_InitialConfig.ForceLoopback)
+	{
+		// Force trigger of opening using local port
+		ZEN_ASSERT(AllowLocalOnly);
+		Result = ERROR_ACCESS_DENIED;
+	}
+	else
 	{
-		// Sharing violation implies the port is being used by another process
-		for (int PortOffset = 1; (Result == ERROR_SHARING_VIOLATION) && (PortOffset < 10); ++PortOffset)
+		Result = HttpAddUrlToUrlGroup(m_HttpUrlGroupId, WildcardUrlPath.c_str(), HTTP_URL_CONTEXT(0), 0);
+
+		if ((Result == ERROR_SHARING_VIOLATION) && AllowPortProbing)
 		{
-			EffectivePort = BasePort + (PortOffset * 100);
-			WildcardUrlPath.Reset();
-			WildcardUrlPath << u8"http://*:"sv << int64_t(EffectivePort) << u8"/"sv;
+			// Sharing violation implies the port is being used by another process
+			for (int PortOffset = 1; (Result == ERROR_SHARING_VIOLATION) && (PortOffset < 10); ++PortOffset)
+			{
+				EffectivePort = BasePort + (PortOffset * 100);
+				WildcardUrlPath.Reset();
+				WildcardUrlPath << u8"http://*:"sv << int64_t(EffectivePort) << u8"/"sv;
 
-			Result = HttpAddUrlToUrlGroup(m_HttpUrlGroupId, WildcardUrlPath.c_str(), HTTP_URL_CONTEXT(0), 0);
+				Result = HttpAddUrlToUrlGroup(m_HttpUrlGroupId, WildcardUrlPath.c_str(), HTTP_URL_CONTEXT(0), 0);
+			}
 		}
 	}