fix: broken normalisePath/normalisePathWin on windows

internal/transformations/normalise_path.go

@@ -1,6 +1,8 @@
 // Copyright 2022 Juan Pablo Tosso and the OWASP Coraza contributors
 // SPDX-License-Identifier: Apache-2.0
 
+//go:build !windows
+
 package transformations
 
 import (
@@ -16,7 +18,10 @@ func normalisePath(data string) (string, bool, error) {
 	if clean == "." {
 		return "", true, nil
 	}
-	if data[len(data)-1] == '/' {
+	// filepath.Clean removes the trailing slash of a directory
+	// it is expected that the output of normalisePath keeps the trailing slash
+	// this if clause checks for trailing / and \ in the input as both are valid options
+	if data[len(data)-1] == '/' || data[len(data)-1] == '\\' {
 		return clean + "/", true, nil
 	}
 	return clean, data != clean, nil

internal/transformations/normalise_path_windows.go

@@ -0,0 +1,30 @@
+// Copyright 2022 Juan Pablo Tosso and the OWASP Coraza contributors
+// SPDX-License-Identifier: Apache-2.0
+
+package transformations
+
+import (
+	"path/filepath"
+	"strings"
+)
+
+func normalisePath(data string) (string, bool, error) {
+	leng := len(data)
+	if leng < 1 {
+		return data, false, nil
+	}
+	clean := filepath.Clean(data)
+	// filepath.Clean uses filepath.Separator for the cleaned path
+	// on windows we need to replace the Separator with the expected forward slash
+	clean = strings.ReplaceAll(clean, string(filepath.Separator), "/")
+	if clean == "." {
+		return "", true, nil
+	}
+	// filepath.Clean removes the trailing slash of a directory
+	// it is expected that the output of normalisePath keeps the trailing slash
+	// this if clause checks for trailing / and \ in the input as both are valid options
+	if data[len(data)-1] == '/' || data[len(data)-1] == '\\' {
+		return clean + "/", true, nil
+	}
+	return clean, data != clean, nil
+}