From 3b006d81e6a4534dd02c45937e4e2d88b9120d23 Mon Sep 17 00:00:00 2001
From: TLS-Attacker Developer <developer@tls-attacker.org>
Date: Thu, 26 Jun 2025 15:13:34 +0000
Subject: [PATCH] Fix timeout issue during connection establishment (#193)

Added serverSocket.setSoTimeout() before accept() call to prevent
indefinite blocking when no client connects. This ensures the server
times out appropriately and throws a SocketTimeoutException.

- Set serverSocket timeout before calling accept()
- Added test to verify timeout behavior works correctly
- Fixes issue where server would hang indefinitely waiting for connections
---
 .../tcp/ServerTcpTransportHandler.java        |  1 +
 .../tcp/ServerTcpTransportHandlerTest.java    | 23 +++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/Transport/src/main/java/de/rub/nds/tlsattacker/transport/tcp/ServerTcpTransportHandler.java b/Transport/src/main/java/de/rub/nds/tlsattacker/transport/tcp/ServerTcpTransportHandler.java
index 8a2e8a22d9..f1f4a86aee 100644
--- a/Transport/src/main/java/de/rub/nds/tlsattacker/transport/tcp/ServerTcpTransportHandler.java
+++ b/Transport/src/main/java/de/rub/nds/tlsattacker/transport/tcp/ServerTcpTransportHandler.java
@@ -72,6 +72,7 @@ public void initialize() throws IOException {
             if (serverSocket == null || serverSocket.isClosed()) {
                 throw new IOException("TransportHandler not preinitialized");
             }
+            serverSocket.setSoTimeout((int) timeout);
             socket = serverSocket.accept();
             socket.setSoTimeout((int) timeout);
         }
diff --git a/Transport/src/test/java/de/rub/nds/tlsattacker/transport/tcp/ServerTcpTransportHandlerTest.java b/Transport/src/test/java/de/rub/nds/tlsattacker/transport/tcp/ServerTcpTransportHandlerTest.java
index 79d208afac..9903c04c72 100644
--- a/Transport/src/test/java/de/rub/nds/tlsattacker/transport/tcp/ServerTcpTransportHandlerTest.java
+++ b/Transport/src/test/java/de/rub/nds/tlsattacker/transport/tcp/ServerTcpTransportHandlerTest.java
@@ -13,6 +13,7 @@
 import de.rub.nds.tlsattacker.util.FreePortFinder;
 import java.io.IOException;
 import java.net.Socket;
+import java.net.SocketTimeoutException;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -91,4 +92,26 @@ public void fullTest() throws IOException {
             assertArrayEquals(new byte[] {4, 3, 2, 1}, received);
         }
     }
+
+    /** Test that serverSocket.accept() timeout works correctly */
+    @Test
+    public void testAcceptTimeout() throws IOException {
+        // Create handler with short timeout
+        ServerTcpTransportHandler timeoutHandler =
+                new ServerTcpTransportHandler(500, 500, FreePortFinder.getPossiblyFreePort());
+        try {
+            timeoutHandler.preInitialize();
+            // Try to initialize without connecting - should timeout
+            assertThrows(
+                    SocketTimeoutException.class,
+                    () -> {
+                        timeoutHandler.initialize();
+                    });
+        } finally {
+            if (timeoutHandler.getServerSocket() != null
+                    && !timeoutHandler.getServerSocket().isClosed()) {
+                timeoutHandler.getServerSocket().close();
+            }
+        }
+    }
 }