Improve Tor startup diagnostics on Windows

src/init.cpp

@@ -1223,7 +1223,10 @@ bool AppInit2()
             fUseUPnP = false;
             #endif
         } else {
-            return InitError(_("Tor failed to start. Triangles requires Tor to operate."));
+            std::string torError = CTorEmbedded::GetInstance()->GetLastError();
+            if (torError.empty())
+                torError = "No detailed Tor startup error was recorded.";
+            return InitError(strprintf(_("Tor failed to start. Triangles requires Tor to operate.\n\nDetails: %s"), torError));
         }
 
         // Initialize Tor V3 identity (Ed25519 keys, onion address)

src/tor/tor_embedded.cpp

@@ -114,6 +114,7 @@ bool CTorEmbedded::Start(int socks, int hsPort, bool enableHiddenService)
 {
     if (running.load()) return true;
 
+    lastError.clear();
     socksPort = socks;
     hiddenServiceEnabled = enableHiddenService;
     hiddenServicePort = hiddenServiceEnabled ? hsPort : 0;
@@ -202,11 +203,13 @@ bool CTorEmbedded::Start(int socks, int hsPort, bool enableHiddenService)
         }
 
         if (!running.load()) {
+            lastError = "Embedded Tor thread exited during bootstrap before the SOCKS proxy became available.";
             printf("ERROR: Embedded Tor thread exited during bootstrap\n");
             return false;
         }
     }
 
+    lastError = strprintf("Embedded Tor did not expose SOCKS port %d within 60 seconds.", socksPort);
     printf("WARNING: Embedded Tor started but SOCKS not ready after 60s (still bootstrapping)\n");
     return true;
 }
@@ -241,8 +244,12 @@ bool CTorEmbedded::Start(int socks, int hsPort, bool enableHiddenService)
     hiddenServiceEnabled = enableHiddenService;
     hiddenServicePort = hiddenServiceEnabled ? hsPort : 0;
     onionHostname.clear();
+    lastError.clear();
     torDataDir = (::GetDataDir() / "tor_data").string();
     running.store(StartTorProcess(torDataDir, socksPort, hiddenServicePort, hiddenServiceEnabled));
+    if (!running.load()) {
+        lastError = CTorProcess::GetInstance()->GetLastError();
+    }
     return running.load();
 }
 

src/tor/tor_embedded.h

@@ -19,6 +19,7 @@ private:
     bool hiddenServiceEnabled;
     std::string torDataDir;
     std::string onionHostname;
+    std::string lastError;
 
 public:
     static CTorEmbedded* GetInstance();
@@ -43,6 +44,8 @@ public:
 
     // Get our .onion address (available after bootstrap)
     std::string GetOnionAddress() const { return onionHostname; }
+    std::string GetLastError() const { return lastError; }
+    void SetLastError(const std::string& value) { lastError = value; }
 
     // Get the hidden service port
     int GetHiddenServicePort() const { return hiddenServicePort; }

src/tor/tor_process.cpp

@@ -232,6 +232,7 @@ bool CTorProcess::WriteTorrc()
 
 bool CTorProcess::Start(const std::string& dataDir, int socks, int hsPort, bool enableHiddenService)
 {
+    lastError.clear();
     socksPort = socks;
     hiddenServiceEnabled = enableHiddenService;
     hiddenServicePort = hiddenServiceEnabled ? hsPort : 0;
@@ -240,6 +241,7 @@ bool CTorProcess::Start(const std::string& dataDir, int socks, int hsPort, bool
     // Check if something is already listening on our SOCKS port
     if (IsPortInUse(socksPort)) {
         printf("Tor SOCKS port %d already in use - assuming Tor is running\n", socksPort);
+        lastError = strprintf("SOCKS port %d is already in use; assuming an existing Tor instance is serving it.", socksPort);
         running = true;
         return true;
     }
@@ -247,6 +249,7 @@ bool CTorProcess::Start(const std::string& dataDir, int socks, int hsPort, bool
     // Find Tor binary
     torBinaryPath = FindTorBinary();
     if (torBinaryPath.empty()) {
+        lastError = "Tor binary was not found in the bundled install or standard search paths.";
         printf("WARNING: Tor binary not found. Install Tor for .onion connectivity.\n");
         printf("  Windows: Download from https://www.torproject.org/download/tor/\n");
         printf("  Linux:   apt install tor  or  yum install tor\n");
@@ -256,6 +259,7 @@ bool CTorProcess::Start(const std::string& dataDir, int socks, int hsPort, bool
 
     // Write configuration
     if (!WriteTorrc()) {
+        lastError = strprintf("Failed to write Tor configuration to %s", torrcPath.c_str());
         printf("ERROR: Failed to write Tor configuration\n");
         return false;
     }
@@ -282,7 +286,9 @@ bool CTorProcess::Start(const std::string& dataDir, int socks, int hsPort, bool
             NULL, NULL,
             &si, &pi))
     {
-        printf("ERROR: Failed to start Tor process (error %lu)\n", GetLastError());
+        DWORD err = GetLastError();
+        lastError = strprintf("CreateProcess failed for Tor binary '%s' with Windows error %lu", torBinaryPath.c_str(), err);
+        printf("ERROR: Failed to start Tor process (error %lu)\n", err);
         return false;
     }
 
@@ -329,6 +335,7 @@ bool CTorProcess::Start(const std::string& dataDir, int socks, int hsPort, bool
             // Defensive check: Tor must not directly occupy the node's hidden-service
             // virtual port. If it does, node startup will fail with a bind collision.
             if (hiddenServiceEnabled && IsPortInUse(hiddenServicePort)) {
+                lastError = strprintf("Port %d is already busy while Tor hidden service is enabled. Another process is likely blocking the node listener.", hiddenServicePort);
                 printf("ERROR: Tor startup collision: hidden service port %d appears busy before node bind.\n",
                        hiddenServicePort);
                 printf("       Refusing to treat Tor as healthy because this would block the node listener.\n");
@@ -353,12 +360,14 @@ bool CTorProcess::Start(const std::string& dataDir, int socks, int hsPort, bool
 
         // Check if Tor process is still alive
         if (!IsRunning()) {
+            lastError = "Tor process exited during bootstrap before the SOCKS port became ready.";
             printf("ERROR: Tor process exited prematurely\n");
             running = false;
             return false;
         }
     }
 
+    lastError = strprintf("Tor process started from '%s' but SOCKS port %d was not ready after 30 seconds.", torBinaryPath.c_str(), socksPort);
     printf("WARNING: Tor started but SOCKS proxy not yet ready after 30s\n");
     printf("  Tor may still be bootstrapping. .onion connections will work once ready.\n");
     return true;

src/tor/tor_process.h

@@ -19,6 +19,7 @@ private:
     std::string torBinaryPath;
     std::string torDataDir;
     std::string torrcPath;
+    std::string lastError;
     int socksPort;
     int hiddenServicePort;
     bool hiddenServiceEnabled;
@@ -59,6 +60,7 @@ public:
 
     // Get the Tor binary path (for diagnostics)
     std::string GetBinaryPath() const { return torBinaryPath; }
+    std::string GetLastError() const { return lastError; }
 
     // Singleton access
     static CTorProcess* GetInstance();