Merge pull request #1561 from projectdiscovery/issue-1543-rand-seed

Implementing incremental expression replacement

v2/pkg/protocols/common/expressions/expressions.go

@@ -41,7 +41,6 @@ func evaluate(data string, base map[string]interface{}) (string, error) {
 	// - complex: containing helper functions [ + variables]
 	// literals like {{2+2}} are not considered expressions
 	expressions := findExpressions(data, marker.ParenthesisOpen, marker.ParenthesisClose, mergeFunctions(dsl.HelperFunctions(), mapToFunctions(base)))
-	dynamicValues := make(map[string]interface{})
 	for _, expression := range expressions {
 		// replace variable placeholders with base values
 		expression = replacer.Replace(expression, base)
@@ -54,10 +53,11 @@ func evaluate(data string, base map[string]interface{}) (string, error) {
 		if err != nil {
 			continue
 		}
-		dynamicValues[expression] = result
+		// replace incrementally
+		data = replacer.ReplaceOne(data, expression, result)
 	}
-	// Replacer dynamic values if any in raw request and parse it
-	return replacer.Replace(data, dynamicValues), nil
+
+	return data, nil
 }
 
 // maxIterations to avoid infinite loop

v2/pkg/protocols/common/replacer/replacer.go

@@ -31,3 +31,14 @@ func Replace(template string, values map[string]interface{}) string {
 	final := replacer.Replace(template)
 	return final
 }
+
+// Replace replaces one placeholder in template with one value on the fly.
+func ReplaceOne(template string, key string, value interface{}) string {
+	data := replaceOneWithMarkers(template, key, value, marker.ParenthesisOpen, marker.ParenthesisClose)
+	return replaceOneWithMarkers(data, key, value, marker.General, marker.General)
+}
+
+// replaceOneWithMarkers is a helper function that perform one time replacement
+func replaceOneWithMarkers(template, key string, value interface{}, openMarker, closeMarker string) string {
+	return strings.Replace(template, openMarker+key+closeMarker, types.ToString(value), 1)
+}