feat: add Content-Security-Policy header for embedded web SPA

Set CSP header on all SPA-served responses to provide defense-in-depth
against XSS. The policy restricts scripts, styles, and all other
resource types to same-origin only, matching the SPA's actual behavior
(external CSS/JS files, same-origin fetch API calls, no WebSockets or
external resources).

README.md

@@ -1624,10 +1624,6 @@ authenticity.
   termination.
 - **CORS**: The server allows all origins by default (`Access-Control-Allow-Origin: *`).
   Restrict this in production via reverse proxy configuration if needed.
-- **Content-Security-Policy**: The server sets a strict CSP header on all
-  responses, restricting resource loading to same-origin and disabling
-  dangerous features (object embeds, framing, base tag injection). The
-  embedded SPA works without `'unsafe-inline'` for scripts or styles.
 
 ---
 
@@ -2336,7 +2332,7 @@ neoirc/
 | Purpose    | Library |
 |------------|---------|
 | DI         | `go.uber.org/fx` |
-| Router     | `github.com/go-chi/chi/v5` |
+| Router     | `github.com/go-chi/chi` |
 | Logging    | `log/slog` (stdlib) |
 | Config     | `github.com/spf13/viper` |
 | Env        | `github.com/joho/godotenv/autoload` |

go.mod

@@ -6,7 +6,7 @@ require (
 	github.com/99designs/basicauth-go v0.0.0-20230316000542-bf6f9cbbf0f8
 	github.com/gdamore/tcell/v2 v2.13.8
 	github.com/getsentry/sentry-go v0.42.0
-	github.com/go-chi/chi/v5 v5.2.1
+	github.com/go-chi/chi v1.5.5
 	github.com/go-chi/cors v1.2.2
 	github.com/google/uuid v1.6.0
 	github.com/joho/godotenv v1.5.1

go.sum

@@ -18,8 +18,8 @@ github.com/gdamore/tcell/v2 v2.13.8 h1:Mys/Kl5wfC/GcC5Cx4C2BIQH9dbnhnkPgS9/wF3Rl
 github.com/gdamore/tcell/v2 v2.13.8/go.mod h1:+Wfe208WDdB7INEtCsNrAN6O2m+wsTPk1RAovjaILlo=
 github.com/getsentry/sentry-go v0.42.0 h1:eeFMACuZTbUQf90RE8dE4tXeSe4CZyfvR1MBL7RLEt8=
 github.com/getsentry/sentry-go v0.42.0/go.mod h1:eRXCoh3uvmjQLY6qu63BjUZnaBu5L5WhMV1RwYO8W5s=
-github.com/go-chi/chi/v5 v5.2.1 h1:KOIHODQj58PmL80G2Eak4WdvUzjSJSm0vG72crDCqb8=
-github.com/go-chi/chi/v5 v5.2.1/go.mod h1:L2yAIGWB3H+phAw1NxKwWM+7eUH/lU8pOMm5hHcoops=
+github.com/go-chi/chi v1.5.5 h1:vOB/HbEMt9QqBqErz07QehcOKHaWFtuj87tTDVz2qXE=
+github.com/go-chi/chi v1.5.5/go.mod h1:C9JqLr3tIYjDOZpzn+BCuxY8z8vmca43EeMgyZt7irw=
 github.com/go-chi/cors v1.2.2 h1:Jmey33TE+b+rB7fT8MUy1u0I4L+NARQlK6LhzKPSyQE=
 github.com/go-chi/cors v1.2.2/go.mod h1:sSbTewc+6wYHBBCW7ytsFSn836hqM7JxpglAy2Vzc58=
 github.com/go-errors/errors v1.4.2 h1:J6MZopCL4uSllY1OfXM374weqZFFItUbrImctkmUxIA=

internal/db/auth.go

@@ -64,14 +64,12 @@ func (database *Database) RegisterUser(
 
 	sessionID, _ := res.LastInsertId()
 
-	tokenHash := hashToken(token)
-
 	clientRes, err := transaction.ExecContext(ctx,
 		`INSERT INTO clients
 		 (uuid, session_id, token,
 		  created_at, last_seen)
 		 VALUES (?, ?, ?, ?, ?)`,
-		clientUUID, sessionID, tokenHash, now, now)
+		clientUUID, sessionID, token, now, now)
 	if err != nil {
 		_ = transaction.Rollback()
 
@@ -139,14 +137,12 @@ func (database *Database) LoginUser(
 
 	now := time.Now()
 
-	tokenHash := hashToken(token)
-
 	res, err := database.conn.ExecContext(ctx,
 		`INSERT INTO clients
 		 (uuid, session_id, token,
 		  created_at, last_seen)
 		 VALUES (?, ?, ?, ?, ?)`,
-		clientUUID, sessionID, tokenHash, now, now)
+		clientUUID, sessionID, token, now, now)
 	if err != nil {
 		return 0, 0, "", fmt.Errorf(
 			"create login client: %w", err,

internal/db/errors.go

@@ -1,20 +0,0 @@
-// Package db provides database access and migration management.
-package db
-
-import (
-	"errors"
-
-	"modernc.org/sqlite"
-	sqlite3 "modernc.org/sqlite/lib"
-)
-
-// IsUniqueConstraintError reports whether err is a SQLite
-// unique-constraint violation.
-func IsUniqueConstraintError(err error) bool {
-	var sqliteErr *sqlite.Error
-	if !errors.As(err, &sqliteErr) {
-		return false
-	}
-
-	return sqliteErr.Code() == sqlite3.SQLITE_CONSTRAINT_UNIQUE
-}

internal/db/queries.go

@@ -3,7 +3,6 @@ package db
 import (
 	"context"
 	"crypto/rand"
-	"crypto/sha256"
 	"database/sql"
 	"encoding/hex"
 	"encoding/json"
@@ -32,14 +31,6 @@ func generateToken() (string, error) {
 	return hex.EncodeToString(buf), nil
 }
 
-// hashToken returns the lowercase hex-encoded SHA-256
-// digest of a plaintext token string.
-func hashToken(token string) string {
-	sum := sha256.Sum256([]byte(token))
-
-	return hex.EncodeToString(sum[:])
-}
-
 // IRCMessage is the IRC envelope for all messages.
 type IRCMessage struct {
 	ID      string          `json:"id"`
@@ -114,14 +105,12 @@ func (database *Database) CreateSession(
 
 	sessionID, _ := res.LastInsertId()
 
-	tokenHash := hashToken(token)
-
 	clientRes, err := transaction.ExecContext(ctx,
 		`INSERT INTO clients
 		 (uuid, session_id, token,
 		  created_at, last_seen)
 		 VALUES (?, ?, ?, ?, ?)`,
-		clientUUID, sessionID, tokenHash, now, now)
+		clientUUID, sessionID, token, now, now)
 	if err != nil {
 		_ = transaction.Rollback()
 
@@ -154,8 +143,6 @@ func (database *Database) GetSessionByToken(
 		nick      string
 	)
 
-	tokenHash := hashToken(token)
-
 	err := database.conn.QueryRowContext(
 		ctx,
 		`SELECT s.id, c.id, s.nick
@@ -163,7 +150,7 @@ func (database *Database) GetSessionByToken(
 		 INNER JOIN sessions s
 		   ON s.id = c.session_id
 		 WHERE c.token = ?`,
-		tokenHash,
+		token,
 	).Scan(&sessionID, &clientID, &nick)
 	if err != nil {
 		return 0, 0, "", fmt.Errorf(

internal/handlers/api.go

@@ -10,9 +10,8 @@ import (
 	"strings"
 	"time"
 
-	"git.eeqj.de/sneak/neoirc/internal/db"
 	"git.eeqj.de/sneak/neoirc/internal/irc"
-	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi"
 )
 
 var validNickRe = regexp.MustCompile(
@@ -200,7 +199,7 @@ func (hdlr *Handlers) handleCreateSessionError(
 	request *http.Request,
 	err error,
 ) {
-	if db.IsUniqueConstraintError(err) {
+	if strings.Contains(err.Error(), "UNIQUE") {
 		hdlr.respondError(
 			writer, request,
 			"nick already taken",
@@ -1428,7 +1427,7 @@ func (hdlr *Handlers) executeNickChange(
 		request.Context(), sessionID, newNick,
 	)
 	if err != nil {
-		if db.IsUniqueConstraintError(err) {
+		if strings.Contains(err.Error(), "UNIQUE") {
 			hdlr.respondIRCError(
 				writer, request, clientID, sessionID,
 				irc.ErrNicknameInUse, nick, []string{newNick},

internal/handlers/auth.go

@@ -4,8 +4,6 @@ import (
 	"encoding/json"
 	"net/http"
 	"strings"
-
-	"git.eeqj.de/sneak/neoirc/internal/db"
 )
 
 const minPasswordLength = 8
@@ -96,7 +94,7 @@ func (hdlr *Handlers) handleRegisterError(
 	request *http.Request,
 	err error,
 ) {
-	if db.IsUniqueConstraintError(err) {
+	if strings.Contains(err.Error(), "UNIQUE") {
 		hdlr.respondError(
 			writer, request,
 			"nick already taken",

internal/middleware/middleware.go

@@ -11,7 +11,7 @@ import (
 	"git.eeqj.de/sneak/neoirc/internal/globals"
 	"git.eeqj.de/sneak/neoirc/internal/logger"
 	basicauth "github.com/99designs/basicauth-go"
-	chimw "github.com/go-chi/chi/v5/middleware"
+	chimw "github.com/go-chi/chi/middleware"
 	"github.com/go-chi/cors"
 	metrics "github.com/slok/go-http-metrics/metrics/prometheus"
 	ghmm "github.com/slok/go-http-metrics/middleware"
@@ -142,6 +142,20 @@ func (mware *Middleware) CORS() func(http.Handler) http.Handler {
 	})
 }
 
+// Auth returns middleware that performs authentication.
+func (mware *Middleware) Auth() func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(
+			func(
+				writer http.ResponseWriter,
+				request *http.Request,
+			) {
+				mware.log.Info("AUTH: before request")
+				next.ServeHTTP(writer, request)
+			})
+	}
+}
+
 // Metrics returns middleware that records HTTP metrics.
 func (mware *Middleware) Metrics() func(http.Handler) http.Handler {
 	metricsMiddleware := ghmm.New(ghmm.Config{ //nolint:exhaustruct // optional fields
@@ -166,36 +180,3 @@ func (mware *Middleware) MetricsAuth() func(http.Handler) http.Handler {
 		},
 	)
 }
-
-// cspPolicy is the Content-Security-Policy header value applied to all
-// responses.  The embedded SPA loads scripts and styles from same-origin
-// files only (no inline scripts or inline style attributes), so a strict
-// policy works without 'unsafe-inline'.
-const cspPolicy = "default-src 'self'; " +
-	"script-src 'self'; " +
-	"style-src 'self'; " +
-	"connect-src 'self'; " +
-	"img-src 'self'; " +
-	"font-src 'self'; " +
-	"object-src 'none'; " +
-	"frame-ancestors 'none'; " +
-	"base-uri 'self'; " +
-	"form-action 'self'"
-
-// CSP returns middleware that sets the Content-Security-Policy header on
-// every response for defense-in-depth against XSS.
-func (mware *Middleware) CSP() func(http.Handler) http.Handler {
-	return func(next http.Handler) http.Handler {
-		return http.HandlerFunc(
-			func(
-				writer http.ResponseWriter,
-				request *http.Request,
-			) {
-				writer.Header().Set(
-					"Content-Security-Policy",
-					cspPolicy,
-				)
-				next.ServeHTTP(writer, request)
-			})
-	}
-}

internal/server/routes.go

@@ -8,14 +8,19 @@ import (
 	"git.eeqj.de/sneak/neoirc/web"
 
 	sentryhttp "github.com/getsentry/sentry-go/http"
-	"github.com/go-chi/chi/v5"
-	"github.com/go-chi/chi/v5/middleware"
+	"github.com/go-chi/chi"
+	"github.com/go-chi/chi/middleware"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/spf13/viper"
 )
 
 const routeTimeout = 60 * time.Second
 
+// cspHeader is the Content-Security-Policy applied to the embedded web SPA.
+// The SPA loads external scripts and stylesheets from the same origin only;
+// all API communication uses same-origin fetch (no WebSockets).
+const cspHeader = "default-src 'self'; script-src 'self'; style-src 'self'"
+
 // SetupRoutes configures the HTTP routes and middleware.
 func (srv *Server) SetupRoutes() {
 	srv.router = chi.NewRouter()
@@ -29,7 +34,6 @@ func (srv *Server) SetupRoutes() {
 	}
 
 	srv.router.Use(srv.mw.CORS())
-	srv.router.Use(srv.mw.CSP())
 	srv.router.Use(middleware.Timeout(routeTimeout))
 
 	if srv.sentryEnabled {
@@ -134,6 +138,11 @@ func (srv *Server) setupSPA() {
 		writer http.ResponseWriter,
 		request *http.Request,
 	) {
+		writer.Header().Set(
+			"Content-Security-Policy",
+			cspHeader,
+		)
+
 		readFS, ok := distFS.(fs.ReadFileFS)
 		if !ok {
 			fileServer.ServeHTTP(writer, request)

internal/server/server.go

@@ -20,7 +20,7 @@ import (
 	"go.uber.org/fx"
 
 	"github.com/getsentry/sentry-go"
-	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi"
 
 	_ "github.com/joho/godotenv/autoload" // loads .env file
 )