chore: add golangci-lint config and fix all lint issues

Enable 15 additional linters (gosec, errorlint, gocritic, modernize,
misspell, bodyclose, sqlclosecheck, nilerr, unconvert, durationcheck,
sloglint, wastedassign, usestdlibvars) with sensible exclusion rules.

Fix all findings: errors.Is for error comparisons, run() pattern in
main to avoid exitAfterDefer, ReadHeaderTimeout for Slowloris
protection, bounds check in escape sequence reader, WaitGroup.Go,
slices.Contains, range-over-int loops, and http.MethodGet constants.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.golangci.yml

@@ -0,0 +1,79 @@
+version: "2"
+
+linters:
+  enable:
+    # Bug detectors.
+    - bodyclose
+    - durationcheck
+    - errorlint
+    - gocritic
+    - nilerr
+    - sqlclosecheck
+
+    # Security.
+    - gosec
+
+    # Style and modernization.
+    - misspell
+    - modernize
+    - unconvert
+    - usestdlibvars
+
+    # Logging.
+    - sloglint
+
+    # Dead code.
+    - wastedassign
+
+  settings:
+    errcheck:
+      exclude-functions:
+        # Terminal I/O writes (honeypot shell output).
+        - fmt.Fprint
+        - fmt.Fprintf
+        # Low-level byte I/O in shell readLine (escape sequences, echo).
+        - (io.ReadWriter).Read
+        - (io.ReadWriter).Write
+        - (io.ReadWriteCloser).Read
+        - (io.ReadWriteCloser).Write
+        - (io.Reader).Read
+        - (io.Writer).Write
+
+    gosec:
+      excludes:
+        # File reads from config paths — expected in a CLI tool.
+        - G304
+        # Weak RNG for shell selection — crypto/rand not needed.
+        - G404
+
+  exclusions:
+    rules:
+      # Ignore unchecked Close() — standard resource cleanup.
+      - linters: [errcheck]
+        text: "Error return value of .+\\.Close.+ is not checked"
+
+      # Ignore unchecked Rollback() — called in error paths before returning.
+      - linters: [errcheck]
+        text: "Error return value of .+\\.Rollback.+ is not checked"
+
+      # Ignore unchecked Reply/Reject — SSH protocol; nothing useful on failure.
+      - linters: [errcheck]
+        text: "Error return value of .+\\.(Reply|Reject).+ is not checked"
+
+      # Test files: allow unchecked errors.
+      - linters: [errcheck]
+        path: "_test\\.go"
+
+      # Test files: InsecureIgnoreHostKey, file permissions, unhandled errors are expected.
+      - linters: [gosec]
+        path: "_test\\.go"
+
+      # Unhandled errors for cleanup/protocol ops — mirrors errcheck exclusions.
+      - linters: [gosec]
+        text: "G104"
+        source: "\\.(Close|Rollback|Reject|Reply|Read|Write)\\("
+
+      # SQL with safe column interpolation from a fixed switch — not user input.
+      - linters: [gosec]
+        text: "G201"
+        path: "internal/storage/"

cmd/oubliette/main.go

@@ -4,12 +4,14 @@ import (
 	"context"
 	"errors"
 	"flag"
+	"fmt"
 	"log/slog"
 	"net/http"
 	"os"
 	"os/signal"
 	"sync"
 	"syscall"
+	"time"
 
 	"git.t-juice.club/torjus/oubliette/internal/config"
 	"git.t-juice.club/torjus/oubliette/internal/server"
@@ -20,13 +22,19 @@ import (
 const Version = "0.2.0"
 
 func main() {
+	if err := run(); err != nil {
+		slog.Error("fatal error", "err", err)
+		os.Exit(1)
+	}
+}
+
+func run() error {
 	configPath := flag.String("config", "oubliette.toml", "path to config file")
 	flag.Parse()
 
 	cfg, err := config.Load(*configPath)
 	if err != nil {
-		slog.Error("failed to load config", "err", err)
-		os.Exit(1)
+		return fmt.Errorf("load config: %w", err)
 	}
 
 	level := new(slog.LevelVar)
@@ -53,8 +61,7 @@ func main() {
 
 	store, err := storage.NewSQLiteStore(cfg.Storage.DBPath)
 	if err != nil {
-		logger.Error("failed to open database", "err", err)
-		os.Exit(1)
+		return fmt.Errorf("open database: %w", err)
 	}
 	defer store.Close()
 
@@ -65,8 +72,7 @@ func main() {
 
 	srv, err := server.New(*cfg, store, logger)
 	if err != nil {
-		logger.Error("failed to create server", "err", err)
-		os.Exit(1)
+		return fmt.Errorf("create server: %w", err)
 	}
 
 	var wg sync.WaitGroup
@@ -75,23 +81,21 @@ func main() {
 	if cfg.Web.Enabled {
 		webHandler, err := web.NewServer(store, logger.With("component", "web"))
 		if err != nil {
-			logger.Error("failed to create web server", "err", err)
-			os.Exit(1)
+			return fmt.Errorf("create web server: %w", err)
 		}
 
 		httpServer := &http.Server{
-			Addr:    cfg.Web.ListenAddr,
-			Handler: webHandler,
+			Addr:              cfg.Web.ListenAddr,
+			Handler:           webHandler,
+			ReadHeaderTimeout: 10 * time.Second,
 		}
 
-		wg.Add(1)
-		go func() {
-			defer wg.Done()
+		wg.Go(func() {
 			logger.Info("web server listening", "addr", cfg.Web.ListenAddr)
 			if err := httpServer.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
 				logger.Error("web server error", "err", err)
 			}
-		}()
+		})
 
 		// Graceful shutdown on context cancellation.
 		go func() {
@@ -103,10 +107,10 @@ func main() {
 	}
 
 	if err := srv.ListenAndServe(ctx); err != nil {
-		logger.Error("server error", "err", err)
-		os.Exit(1)
+		return fmt.Errorf("server: %w", err)
 	}
 
 	wg.Wait()
 	logger.Info("server stopped")
+	return nil
 }

internal/auth/auth_test.go

@@ -36,7 +36,7 @@ func TestStaticCredentialsWrongPassword(t *testing.T) {
 
 func TestRejectionBeforeThreshold(t *testing.T) {
 	a := newTestAuth(3, time.Hour)
-	for i := 0; i < 2; i++ {
+	for i := range 2 {
 		d := a.Authenticate("1.2.3.4", "user", "pass")
 		if d.Accepted {
 			t.Fatalf("attempt %d should be rejected", i+1)
@@ -49,7 +49,7 @@ func TestRejectionBeforeThreshold(t *testing.T) {
 
 func TestThresholdAcceptance(t *testing.T) {
 	a := newTestAuth(3, time.Hour)
-	for i := 0; i < 2; i++ {
+	for i := range 2 {
 		d := a.Authenticate("1.2.3.4", "user", "pass")
 		if d.Accepted {
 			t.Fatalf("attempt %d should be rejected", i+1)
@@ -65,7 +65,7 @@ func TestPerIPIsolation(t *testing.T) {
 	a := newTestAuth(3, time.Hour)
 
 	// IP1 gets 2 failures.
-	for i := 0; i < 2; i++ {
+	for range 2 {
 		a.Authenticate("1.1.1.1", "user", "pass")
 	}
 
@@ -157,12 +157,10 @@ func TestConcurrentAccess(t *testing.T) {
 	a := newTestAuth(5, time.Hour)
 	var wg sync.WaitGroup
 
-	for i := 0; i < 100; i++ {
-		wg.Add(1)
-		go func() {
-			defer wg.Done()
+	for range 100 {
+		wg.Go(func() {
 			a.Authenticate("1.2.3.4", "user", "pass")
-		}()
+		})
 	}
 	wg.Wait()
 }

internal/detection/scorer_test.go

@@ -87,7 +87,7 @@ func TestScorer_OutputIgnored(t *testing.T) {
 	now := time.Now()
 
 	// Only output events — should not affect score.
-	for i := 0; i < 100; i++ {
+	for range 100 {
 		s.RecordEvent(now, DirOutput, []byte("some output\n"))
 		now = now.Add(10 * time.Millisecond)
 	}
@@ -103,25 +103,21 @@ func TestScorer_ThreadSafety(t *testing.T) {
 	now := time.Now()
 
 	var wg sync.WaitGroup
-	for i := 0; i < 10; i++ {
-		wg.Add(1)
-		go func(offset int) {
-			defer wg.Done()
-			for j := 0; j < 100; j++ {
-				ts := now.Add(time.Duration(offset*100+j) * time.Millisecond)
+	for i := range 10 {
+		wg.Go(func() {
+			for j := range 100 {
+				ts := now.Add(time.Duration(i*100+j) * time.Millisecond)
 				s.RecordEvent(ts, DirInput, []byte("a"))
 			}
-		}(i)
+		})
 	}
 
 	// Concurrently read score.
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
-		for i := 0; i < 50; i++ {
+	wg.Go(func() {
+		for range 50 {
 			_ = s.Score()
 		}
-	}()
+	})
 
 	wg.Wait()
 

internal/notify/webhook.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"log/slog"
 	"net/http"
+	"slices"
 	"sync"
 	"time"
 
@@ -98,12 +99,7 @@ func (n *Notifier) shouldSend(wh config.WebhookNotifyConfig, eventType string) b
 	if len(wh.Events) == 0 {
 		return true // empty = all events
 	}
-	for _, ev := range wh.Events {
-		if ev == eventType {
-			return true
-		}
-	}
-	return false
+	return slices.Contains(wh.Events, eventType)
 }
 
 func (n *Notifier) send(ctx context.Context, wh config.WebhookNotifyConfig, payload webhookPayload) {

internal/shell/bash/bash.go

@@ -2,6 +2,7 @@ package bash
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"strings"
@@ -55,7 +56,7 @@ func (b *BashShell) Handle(ctx context.Context, sess *shell.SessionContext, rw i
 		}
 
 		line, err := readLine(ctx, rw)
-		if err == io.EOF {
+		if errors.Is(err, io.EOF) {
 			fmt.Fprint(rw, "logout\r\n")
 			return nil
 		}
@@ -81,7 +82,9 @@ func (b *BashShell) Handle(ctx context.Context, sess *shell.SessionContext, rw i
 
 		// Log command and output to store.
 		if sess.Store != nil {
-			sess.Store.AppendSessionLog(ctx, sess.SessionID, trimmed, output)
+			if err := sess.Store.AppendSessionLog(ctx, sess.SessionID, trimmed, output); err != nil {
+				return fmt.Errorf("append session log: %w", err)
+			}
 		}
 
 		if result.exit {
@@ -145,8 +148,7 @@ func readLine(ctx context.Context, rw io.ReadWriter) (string, error) {
 			// Read and discard the rest of the escape sequence.
 			// Most are 3 bytes: ESC [ X (arrow keys, etc.)
 			next := make([]byte, 1)
-			rw.Read(next)
-			if next[0] == '[' {
+			if n, _ := rw.Read(next); n > 0 && next[0] == '[' {
 				rw.Read(next) // read the final byte
 			}
 

internal/shell/bash/bash_test.go

@@ -3,6 +3,7 @@ package bash
 import (
 	"bytes"
 	"context"
+	"errors"
 	"io"
 	"strings"
 	"testing"
@@ -108,7 +109,7 @@ func TestReadLineCtrlD(t *testing.T) {
 
 	ctx := context.Background()
 	_, err := readLine(ctx, rw)
-	if err != io.EOF {
+	if !errors.Is(err, io.EOF) {
 		t.Fatalf("expected io.EOF, got %v", err)
 	}
 }

internal/storage/sqlite_test.go

@@ -205,11 +205,7 @@ func TestDeleteRecordsBefore(t *testing.T) {
 }
 
 func TestNewSQLiteStoreCreatesFile(t *testing.T) {
-	dbPath := filepath.Join(t.TempDir(), "subdir", "test.db")
-	// Parent directory doesn't exist yet; SQLite should create it.
-	// Actually, SQLite doesn't create parent dirs, but the file itself.
-	// Use a path in the temp dir directly.
-	dbPath = filepath.Join(t.TempDir(), "test.db")
+	dbPath := filepath.Join(t.TempDir(), "test.db")
 	store, err := NewSQLiteStore(dbPath)
 	if err != nil {
 		t.Fatalf("creating store: %v", err)

internal/storage/store_test.go

@@ -37,17 +37,17 @@ func seedData(t *testing.T, store Store) {
 	ctx := context.Background()
 
 	// Login attempts: root/toor from two IPs, admin/admin from one IP.
-	for i := 0; i < 5; i++ {
+	for range 5 {
 		if err := store.RecordLoginAttempt(ctx, "root", "toor", "10.0.0.1"); err != nil {
 			t.Fatalf("seeding attempt: %v", err)
 		}
 	}
-	for i := 0; i < 3; i++ {
+	for range 3 {
 		if err := store.RecordLoginAttempt(ctx, "root", "toor", "10.0.0.2"); err != nil {
 			t.Fatalf("seeding attempt: %v", err)
 		}
 	}
-	for i := 0; i < 2; i++ {
+	for range 2 {
 		if err := store.RecordLoginAttempt(ctx, "admin", "admin", "10.0.0.1"); err != nil {
 			t.Fatalf("seeding attempt: %v", err)
 		}

internal/web/web_test.go

@@ -27,7 +27,7 @@ func newSeededTestServer(t *testing.T) *Server {
 	store := storage.NewMemoryStore()
 	ctx := context.Background()
 
-	for i := 0; i < 5; i++ {
+	for range 5 {
 		if err := store.RecordLoginAttempt(ctx, "root", "toor", "10.0.0.1"); err != nil {
 			t.Fatalf("seeding attempt: %v", err)
 		}
@@ -54,7 +54,7 @@ func newSeededTestServer(t *testing.T) *Server {
 func TestDashboardHandler(t *testing.T) {
 	t.Run("empty store", func(t *testing.T) {
 		srv := newTestServer(t)
-		req := httptest.NewRequest("GET", "/", nil)
+		req := httptest.NewRequest(http.MethodGet, "/", nil)
 		w := httptest.NewRecorder()
 
 		srv.ServeHTTP(w, req)
@@ -73,7 +73,7 @@ func TestDashboardHandler(t *testing.T) {
 
 	t.Run("with data", func(t *testing.T) {
 		srv := newSeededTestServer(t)
-		req := httptest.NewRequest("GET", "/", nil)
+		req := httptest.NewRequest(http.MethodGet, "/", nil)
 		w := httptest.NewRecorder()
 
 		srv.ServeHTTP(w, req)
@@ -93,7 +93,7 @@ func TestDashboardHandler(t *testing.T) {
 
 func TestFragmentStats(t *testing.T) {
 	srv := newSeededTestServer(t)
-	req := httptest.NewRequest("GET", "/fragments/stats", nil)
+	req := httptest.NewRequest(http.MethodGet, "/fragments/stats", nil)
 	w := httptest.NewRecorder()
 
 	srv.ServeHTTP(w, req)
@@ -113,7 +113,7 @@ func TestFragmentStats(t *testing.T) {
 
 func TestFragmentActiveSessions(t *testing.T) {
 	srv := newSeededTestServer(t)
-	req := httptest.NewRequest("GET", "/fragments/active-sessions", nil)
+	req := httptest.NewRequest(http.MethodGet, "/fragments/active-sessions", nil)
 	w := httptest.NewRecorder()
 
 	srv.ServeHTTP(w, req)
@@ -144,7 +144,7 @@ func TestStaticAssets(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.path, func(t *testing.T) {
-			req := httptest.NewRequest("GET", tt.path, nil)
+			req := httptest.NewRequest(http.MethodGet, tt.path, nil)
 			w := httptest.NewRecorder()
 
 			srv.ServeHTTP(w, req)