1 files changed, 51 insertions, 0 deletions
diff --git a/api/middleware/auth.go b/api/middleware/auth.go
new file mode 100644
index 0000000..f6e5c4b
--- /dev/null
+++ b/api/middleware/auth.go
@@ -0,0 +1,51 @@
+package middleware
+
+import (
+	"crypto/subtle"
+	"fmt"
+	"net/http"
+	"strings"
+
+	"git.leonardobishop.net/stash/api/dto"
+)
+
+func MustAuthenticate(token string) func(http.HandlerFunc) http.HandlerFunc {
+	return func(next http.HandlerFunc) http.HandlerFunc {
+		return func(w http.ResponseWriter, r *http.Request) {
+			authHeader := r.Header.Get("Authorization")
+			givenToken, err := extractBearerToken(authHeader)
+			if err != nil {
+				dto.WriteDto(w, r, &dto.ErrorResponse{
+					Code:    http.StatusUnauthorized,
+					Message: "Unauthorized",
+				})
+				return
+			}
+
+			if subtle.ConstantTimeCompare([]byte(token), []byte(givenToken)) != 1 {
+				dto.WriteDto(w, r, &dto.ErrorResponse{
+					Code:    http.StatusForbidden,
+					Message: "Forbidden",
+				})
+				return
+			}
+
+			next(w, r)
+		}
+	}
+}
+
+func extractBearerToken(header string) (string, error) {
+	const prefix = "Bearer "
+	if header == "" {
+		return "", fmt.Errorf("authorization header missing")
+	}
+	if !strings.HasPrefix(header, prefix) {
+		return "", fmt.Errorf("invalid authorization scheme")
+	}
+	token := strings.TrimSpace(header[len(prefix):])
+	if token == "" {
+		return "", fmt.Errorf("token is empty")
+	}
+	return token, nil
+}