refactor(lib): keep server URL state local

Signed-off-by: Jason Cameron <jason.cameron@stanwith.me>

lib/anubis.go

@@ -13,6 +13,7 @@ import (
 	"net/url"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/golang-jwt/jwt/v5"
@@ -97,6 +98,8 @@ type Server struct {
 	OGTags      *ogtags.OGTagCache
 	logger      *slog.Logger
 	opts        Options
+	basePrefix  string
+	publicURL   string
 	ed25519Priv ed25519.PrivateKey
 	hs512Secret []byte
 }
@@ -123,6 +126,50 @@ func (s *Server) getRequestLogger(r *http.Request) (*slog.Logger, *http.Request)
 	return lg, r
 }
 
+var anubisBasePrefixMu sync.Mutex
+
+func (s *Server) configuredBasePrefix() string {
+	if s.basePrefix != "" {
+		return s.basePrefix
+	}
+	return strings.TrimRight(s.opts.BasePrefix, "/")
+}
+
+func (s *Server) configuredPublicURL() string {
+	if s.publicURL != "" {
+		return s.publicURL
+	}
+	return s.opts.PublicUrl
+}
+
+func (s *Server) prefixedPath(path string) string {
+	if !strings.HasPrefix(path, "/") {
+		path = "/" + path
+	}
+	return s.configuredBasePrefix() + path
+}
+
+func (s *Server) cookiePath() string {
+	basePrefix := s.configuredBasePrefix()
+	if basePrefix == "" {
+		return "/"
+	}
+	return basePrefix + "/"
+}
+
+func (s *Server) withAnubisBasePrefix(fn func()) {
+	anubisBasePrefixMu.Lock()
+	defer anubisBasePrefixMu.Unlock()
+
+	oldBasePrefix := anubis.BasePrefix
+	anubis.BasePrefix = s.configuredBasePrefix()
+	defer func() {
+		anubis.BasePrefix = oldBasePrefix
+	}()
+
+	fn()
+}
+
 func (s *Server) getTokenKeyfunc() jwt.Keyfunc {
 	// return ED25519 key if HS512 is not set
 	if len(s.hs512Secret) == 0 {
@@ -246,11 +293,7 @@ func (s *Server) maybeReverseProxy(w http.ResponseWriter, r *http.Request, httpS
 		return
 	}
 
-	// Adjust cookie path if base prefix is not empty
-	cookiePath := "/"
-	if anubis.BasePrefix != "" {
-		cookiePath = strings.TrimSuffix(anubis.BasePrefix, "/") + "/"
-	}
+	cookiePath := s.cookiePath()
 
 	cr, rule, err := s.check(r, lg)
 	if err != nil {
@@ -344,11 +387,7 @@ func (s *Server) maybeReverseProxy(w http.ResponseWriter, r *http.Request, httpS
 }
 
 func (s *Server) checkRules(w http.ResponseWriter, r *http.Request, cr policy.CheckResult, lg *slog.Logger, rule *policy.Bot) bool {
-	// Adjust cookie path if base prefix is not empty
-	cookiePath := "/"
-	if anubis.BasePrefix != "" {
-		cookiePath = strings.TrimSuffix(anubis.BasePrefix, "/") + "/"
-	}
+	cookiePath := s.cookiePath()
 
 	localizer := localization.GetLocalizer(r)
 
@@ -511,11 +550,7 @@ func (s *Server) PassChallenge(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	// Adjust cookie path if base prefix is not empty
-	cookiePath := "/"
-	if anubis.BasePrefix != "" {
-		cookiePath = strings.TrimSuffix(anubis.BasePrefix, "/") + "/"
-	}
+	cookiePath := s.cookiePath()
 
 	if _, err := r.Cookie(anubis.TestCookieName); errors.Is(err, http.ErrNoCookie) {
 		s.ClearCookie(w, CookieOpts{Path: cookiePath, Host: r.Host})