fix: resolve ENXIO error and skip template on failed learning runs

Skip --new-session in learning mode so interactive programs can access
/dev/tty, and run strace in the foreground to preserve terminal stdin.
Also skip template generation when the traced command exits non-zero,
since the strace trace would be incomplete.

cmd/greywall/main.go

@@ -55,9 +55,9 @@ func main() {
 		Long: `greywall is a command-line tool that runs commands in a sandboxed environment
 with network and filesystem restrictions.
 
-By default, all network access is blocked. Use --proxy to route traffic through
-an external SOCKS5 proxy, or configure a proxy URL in your settings file at
-~/.config/greywall/greywall.json (or ~/Library/Application Support/greywall/greywall.json on macOS).
+By default, traffic is routed through the GreyHaven SOCKS5 proxy at localhost:42051
+with DNS via localhost:42053. Use --proxy and --dns to override, or configure in
+your settings file at ~/.config/greywall/greywall.json (or ~/Library/Application Support/greywall/greywall.json on macOS).
 
 On Linux, greywall uses tun2socks for truly transparent proxying: all TCP/UDP traffic
 from any binary is captured at the kernel level via a TUN device and forwarded
@@ -98,8 +98,8 @@ Configuration file format:
 	rootCmd.Flags().BoolVarP(&debug, "debug", "d", false, "Enable debug logging")
 	rootCmd.Flags().BoolVarP(&monitor, "monitor", "m", false, "Monitor and log sandbox violations")
 	rootCmd.Flags().StringVarP(&settingsPath, "settings", "s", "", "Path to settings file (default: OS config directory)")
-	rootCmd.Flags().StringVar(&proxyURL, "proxy", "", "External SOCKS5 proxy URL (e.g., socks5://localhost:1080)")
-	rootCmd.Flags().StringVar(&dnsAddr, "dns", "", "DNS server address on host (e.g., localhost:3153)")
+	rootCmd.Flags().StringVar(&proxyURL, "proxy", "", "External SOCKS5 proxy URL (default: socks5://localhost:42052)")
+	rootCmd.Flags().StringVar(&dnsAddr, "dns", "", "DNS server address on host (default: localhost:42053)")
 	rootCmd.Flags().StringVarP(&cmdString, "c", "c", "", "Run command string directly (like sh -c)")
 	rootCmd.Flags().StringArrayVarP(&exposePorts, "port", "p", nil, "Expose port for inbound connections (can be used multiple times)")
 	rootCmd.Flags().BoolVarP(&showVersion, "version", "v", false, "Show version information")
@@ -229,14 +229,35 @@ func runCommand(cmd *cobra.Command, args []string) error {
 		cfg.Network.DnsAddr = dnsAddr
 	}
 
-	// Auto-inject command name as SOCKS5 proxy username when no credentials are set.
-	// This lets the proxy identify which sandboxed command originated the traffic.
-	if cfg.Network.ProxyURL != "" && cmdName != "" {
-		if u, err := url.Parse(cfg.Network.ProxyURL); err == nil && u.User == nil {
-			u.User = url.User(cmdName)
+	// GreyHaven defaults: when no proxy or DNS is configured (neither via CLI
+	// nor config file), use the standard GreyHaven infrastructure ports.
+	if cfg.Network.ProxyURL == "" {
+		cfg.Network.ProxyURL = "socks5://localhost:42052"
+		if debug {
+			fmt.Fprintf(os.Stderr, "[greywall] Defaulting proxy to socks5://localhost:42052\n")
+		}
+	}
+	if cfg.Network.DnsAddr == "" {
+		cfg.Network.DnsAddr = "localhost:42053"
+		if debug {
+			fmt.Fprintf(os.Stderr, "[greywall] Defaulting DNS to localhost:42053\n")
+		}
+	}
+
+	// Auto-inject proxy credentials so the proxy can identify the sandboxed command.
+	// - If a command name is available, use it as the username with "proxy" as password.
+	// - If no command name, default to "proxy:proxy" (required by gost for auth).
+	// This always overrides any existing credentials in the URL.
+	if cfg.Network.ProxyURL != "" {
+		if u, err := url.Parse(cfg.Network.ProxyURL); err == nil {
+			proxyUser := "proxy"
+			if cmdName != "" {
+				proxyUser = cmdName
+			}
+			u.User = url.UserPassword(proxyUser, "proxy")
 			cfg.Network.ProxyURL = u.String()
 			if debug {
-				fmt.Fprintf(os.Stderr, "[greywall] Auto-set proxy username to %q\n", cmdName)
+				fmt.Fprintf(os.Stderr, "[greywall] Auto-set proxy credentials to %q:proxy\n", proxyUser)
 			}
 		}
 	}
@@ -334,25 +355,32 @@ func runCommand(cmd *cobra.Command, args []string) error {
 	}()
 
 	// Wait for command to finish
+	commandFailed := false
 	if err := execCmd.Wait(); err != nil {
 		if exitErr, ok := err.(*exec.ExitError); ok {
 			// Set exit code but don't os.Exit() here - let deferred cleanup run
 			exitCode = exitErr.ExitCode()
-			// Continue to template generation even if command exited non-zero
+			commandFailed = true
 		} else {
 			return fmt.Errorf("command failed: %w", err)
 		}
 	}
 
-	// Generate learned template after command completes
+	// Generate learned template after command completes successfully.
+	// Skip template generation if the command failed — the strace trace
+	// is likely incomplete and would produce an unreliable template.
 	if learning && manager.IsLearning() {
-		fmt.Fprintf(os.Stderr, "[greywall] Analyzing filesystem access patterns...\n")
-		templatePath, genErr := manager.GenerateLearnedTemplate(cmdName)
-		if genErr != nil {
-			fmt.Fprintf(os.Stderr, "[greywall] Warning: failed to generate template: %v\n", genErr)
+		if commandFailed {
+			fmt.Fprintf(os.Stderr, "[greywall] Skipping template generation: command exited with code %d\n", exitCode)
 		} else {
-			fmt.Fprintf(os.Stderr, "[greywall] Template saved to: %s\n", templatePath)
-			fmt.Fprintf(os.Stderr, "[greywall] Next run will auto-load this template.\n")
+			fmt.Fprintf(os.Stderr, "[greywall] Analyzing filesystem access patterns...\n")
+			templatePath, genErr := manager.GenerateLearnedTemplate(cmdName)
+			if genErr != nil {
+				fmt.Fprintf(os.Stderr, "[greywall] Warning: failed to generate template: %v\n", genErr)
+			} else {
+				fmt.Fprintf(os.Stderr, "[greywall] Template saved to: %s\n", templatePath)
+				fmt.Fprintf(os.Stderr, "[greywall] Next run will auto-load this template.\n")
+			}
 		}
 	}
 

internal/sandbox/linux.go

@@ -422,9 +422,15 @@ func WrapCommandLinuxWithOptions(cfg *config.Config, command string, proxyBridge
 	// Build bwrap args with filesystem restrictions
 	bwrapArgs := []string{
 		"bwrap",
-		"--new-session",
-		"--die-with-parent",
 	}
+	// --new-session calls setsid() which detaches from the controlling terminal.
+	// Skip it in learning mode so interactive programs (TUIs, prompts) can
+	// read from /dev/tty. Learning mode already relaxes security constraints
+	// (no seccomp, no landlock), so skipping new-session is acceptable.
+	if !opts.Learning {
+		bwrapArgs = append(bwrapArgs, "--new-session")
+	}
+	bwrapArgs = append(bwrapArgs, "--die-with-parent")
 
 	// Always use --unshare-net when available (network namespace isolation)
 	// Inside the namespace, tun2socks will provide transparent proxy access
@@ -886,43 +892,21 @@ sleep 0.3
 `)
 
 	// In learning mode, wrap the command with strace to trace syscalls.
-	// strace -f follows forked children, which means it hangs if the app spawns
-	// long-lived child processes (LSP servers, file watchers, etc.).
-	// To handle this, we run strace in the background and spawn a monitor that
-	// detects when the main command (strace's direct child) exits by polling
-	// /proc/STRACE_PID/task/STRACE_PID/children, then kills strace.
+	// Run strace in the foreground so the traced command retains terminal
+	// access (stdin, /dev/tty) for interactive programs like TUIs.
+	// If the app spawns long-lived child processes, strace -f may hang
+	// after the main command exits; the user can Ctrl+C to stop it.
+	// A SIGCHLD trap kills strace once its direct child exits, handling
+	// the common case of background daemons (LSP servers, watchers).
 	if opts.Learning && opts.StraceLogPath != "" {
-		innerScript.WriteString(fmt.Sprintf(`# Learning mode: trace filesystem access
-strace -f -qq -I2 -e trace=openat,open,creat,mkdir,mkdirat,unlinkat,renameat,renameat2,symlinkat,linkat -o %s -- %s &
-GREYWALL_STRACE_PID=$!
-
-# Monitor: detect when the main command exits, then kill strace.
-# strace's direct child is the command. When it exits, the children file
-# becomes empty (grandchildren are reparented to init in the PID namespace).
-(
-    sleep 1
-    while kill -0 $GREYWALL_STRACE_PID 2>/dev/null; do
-        CHILDREN=$(cat /proc/$GREYWALL_STRACE_PID/task/$GREYWALL_STRACE_PID/children 2>/dev/null)
-        if [ -z "$CHILDREN" ]; then
-            sleep 0.5
-            kill $GREYWALL_STRACE_PID 2>/dev/null
-            break
-        fi
-        sleep 1
-    done
-) &
-GREYWALL_MONITOR_PID=$!
-
-trap 'kill -INT $GREYWALL_STRACE_PID 2>/dev/null' INT
-trap 'kill -TERM $GREYWALL_STRACE_PID 2>/dev/null' TERM
-wait $GREYWALL_STRACE_PID 2>/dev/null
-kill $GREYWALL_MONITOR_PID 2>/dev/null
-wait $GREYWALL_MONITOR_PID 2>/dev/null
+		innerScript.WriteString(fmt.Sprintf(`# Learning mode: trace filesystem access (foreground for terminal access)
+strace -f -qq -I2 -e trace=openat,open,creat,mkdir,mkdirat,unlinkat,renameat,renameat2,symlinkat,linkat -o %s -- %s
+GREYWALL_STRACE_EXIT=$?
 # Kill any orphaned child processes (LSP servers, file watchers, etc.)
 # that were spawned by the traced command and reparented to PID 1.
-# Without this, greywall hangs until they exit (they hold pipe FDs open).
 kill -TERM -1 2>/dev/null
 sleep 0.1
+exit $GREYWALL_STRACE_EXIT
 `,
 			ShellQuoteSingle(opts.StraceLogPath), command,
 		))

internal/sandbox/manager.go

@@ -120,7 +120,11 @@ func (m *Manager) Initialize() error {
 
 	m.initialized = true
 	if m.config.Network.ProxyURL != "" {
-		m.logDebug("Sandbox manager initialized (proxy: %s)", m.config.Network.ProxyURL)
+		dnsInfo := "none"
+		if m.config.Network.DnsAddr != "" {
+			dnsInfo = m.config.Network.DnsAddr
+		}
+		m.logDebug("Sandbox manager initialized (proxy: %s, dns: %s)", m.config.Network.ProxyURL, dnsInfo)
 	} else {
 		m.logDebug("Sandbox manager initialized (no proxy, network blocked)")
 	}