fix: refactoring previous fix in attempt to address ongoing issues

See #211 and #215

lib/request.go

@@ -0,0 +1,57 @@
+package lib
+
+import (
+	"errors"
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+type request struct {
+	method      string
+	path        string
+	destination string
+}
+
+func newRequest(r *http.Request, prefix string) (*request, error) {
+	ctx := &request{
+		method: r.Method,
+	}
+
+	if destination := r.Header.Get("Destination"); destination != "" {
+		u, err := url.Parse(destination)
+		if err != nil {
+			return nil, errors.New("invalid destination header")
+		}
+
+		if prefix != "" {
+			destination = strings.TrimPrefix(u.Path, prefix)
+			if len(destination) >= len(u.Path) {
+				return nil, errors.New("invalid url prefix")
+			}
+		}
+
+		if !strings.HasPrefix(destination, "/") {
+			destination = "/" + destination
+		}
+
+		ctx.destination = destination
+	}
+
+	path := r.URL.Path
+
+	if prefix != "" {
+		path = strings.TrimPrefix(r.URL.Path, prefix)
+		if len(path) >= len(r.URL.Path) {
+			return nil, errors.New("invalid url prefix")
+		}
+	}
+
+	if !strings.HasPrefix(path, "/") {
+		path = "/" + path
+	}
+
+	ctx.path = path
+
+	return ctx, nil
+}