security: enforce csrf on writes

internal/server/routes.go

@@ -73,7 +73,8 @@ func NewRouter(cfg Config) http.Handler {
 	mux.HandleFunc("/api/watchlist/", watchlistHandler.HandleDeleteWatchlist)
 	mux.HandleFunc("/watchlist", watchlistHandler.HandleGetWatchlist)
 
-	// Wrap mux with global auth checking, THEN auth context parsing
+	// Wrap mux with global CSRF origin verification and auth checking,
-	protectedHandler := middleware.RequireGlobalAuth(mux)
+	// THEN auth context parsing.
+	protectedHandler := middleware.RequireGlobalAuth(middleware.VerifyOrigin(mux))
 	return middleware.Auth(cfg.AuthService)(protectedHandler)
 }

internal/shared/middleware/logging.go

@@ -0,0 +1,76 @@
+package middleware
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"net"
+	"net/http"
+	"time"
+)
+
+type statusRecorder struct {
+	http.ResponseWriter
+	statusCode  int
+	wroteHeader bool
+}
+
+func newStatusRecorder(w http.ResponseWriter) *statusRecorder {
+	return &statusRecorder{
+		ResponseWriter: w,
+		statusCode:     http.StatusOK,
+	}
+}
+
+func (rw *statusRecorder) WriteHeader(code int) {
+	if rw.wroteHeader {
+		return
+	}
+	rw.statusCode = code
+	rw.wroteHeader = true
+	rw.ResponseWriter.WriteHeader(code)
+}
+
+func (rw *statusRecorder) Write(b []byte) (int, error) {
+	if !rw.wroteHeader {
+		rw.WriteHeader(http.StatusOK)
+	}
+	return rw.ResponseWriter.Write(b)
+}
+
+func (rw *statusRecorder) Flush() {
+	if flusher, ok := rw.ResponseWriter.(http.Flusher); ok {
+		flusher.Flush()
+	}
+}
+
+func (rw *statusRecorder) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	hijacker, ok := rw.ResponseWriter.(http.Hijacker)
+	if !ok {
+		return nil, nil, fmt.Errorf("response writer does not support hijacking")
+	}
+	return hijacker.Hijack()
+}
+
+func (rw *statusRecorder) Push(target string, opts *http.PushOptions) error {
+	pusher, ok := rw.ResponseWriter.(http.Pusher)
+	if !ok {
+		return http.ErrNotSupported
+	}
+	return pusher.Push(target, opts)
+}
+
+func (rw *statusRecorder) Unwrap() http.ResponseWriter {
+	return rw.ResponseWriter
+}
+
+func RequestLogger(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		start := time.Now()
+		recorder := newStatusRecorder(w)
+
+		next.ServeHTTP(recorder, r)
+
+		log.Printf("%s %s %d %s", r.Method, r.URL.Path, recorder.statusCode, time.Since(start))
+	})
+}