fuzz: p2p: Detect peer deadlocks

Author: MarcoFalke

src/test/fuzz/process_messages.cpp

@@ -78,13 +78,17 @@ FUZZ_TARGET(process_messages, .init = initialize_process_messages)
 
         connman.FlushSendBuffer(random_node);
         (void)connman.ReceiveMsgFrom(random_node, std::move(net_msg));
-        random_node.fPauseSend = false;
 
-        try {
-            connman.ProcessMessagesOnce(random_node);
-        } catch (const std::ios_base::failure&) {
+        bool more_work{true};
+        while (more_work) { // Ensure that every message is eventually processed in some way or another
+            random_node.fPauseSend = false;
+
+            try {
+                more_work = connman.ProcessMessagesOnce(random_node);
+            } catch (const std::ios_base::failure&) {
+            }
+            g_setup->m_node.peerman->SendMessages(&random_node);
         }
-        g_setup->m_node.peerman->SendMessages(&random_node);
     }
     SyncWithValidationInterfaceQueue();
     g_setup->m_node.connman->StopNodes();

src/test/util/net.h

@@ -70,7 +70,10 @@ struct ConnmanTestMsg : public CConnman {
                    bool relay_txs)
         EXCLUSIVE_LOCKS_REQUIRED(NetEventsInterface::g_msgproc_mutex);
 
-    void ProcessMessagesOnce(CNode& node) EXCLUSIVE_LOCKS_REQUIRED(NetEventsInterface::g_msgproc_mutex) { m_msgproc->ProcessMessages(&node, flagInterruptMsgProc); }
+    bool ProcessMessagesOnce(CNode& node) EXCLUSIVE_LOCKS_REQUIRED(NetEventsInterface::g_msgproc_mutex)
+    {
+        return m_msgproc->ProcessMessages(&node, flagInterruptMsgProc);
+    }
 
     void NodeReceiveMsgBytes(CNode& node, Span<const uint8_t> msg_bytes, bool& complete) const;