Revert "Removes a regex optimization added at #1536"

This reverts commit fa7973a.

Author: Felipe Zimmerle

src/operators/rx.cc

@@ -33,14 +33,17 @@ bool Rx::evaluate(Transaction *transaction, Rule *rule,
     const std::string& input, std::shared_ptr<RuleMessage> ruleMessage) {
     SMatch match;
     std::list<SMatch> matches;
-    Regex *re;
+    Regex * re = m_re;
 
     if (m_param.empty()) {
         return true;
     }
 
     std::string eparam = MacroExpansion::expand(m_param, transaction);
-    re = new Regex(eparam);
+
+    if (eparam != m_param) {
+        re = new Regex(eparam);
+    }
 
     matches = re->searchAll(input);
     if (rule && rule->getActionsByName("capture").size() > 0 && transaction) {
@@ -62,7 +65,9 @@ bool Rx::evaluate(Transaction *transaction, Rule *rule,
         logOffset(ruleMessage, i.m_offset, i.m_length);
     }
 
-    delete re;
+    if (re != m_re) {
+        delete re;
+    }
 
     if (matches.size() > 0) {
         return true;

src/operators/rx.h

@@ -37,15 +37,19 @@ class Rx : public Operator {
     /** @ingroup ModSecurity_Operator */
     Rx(std::string op, std::string param, bool negation)
         : Operator(op, param, negation) {
+        m_re = new Regex(param);
         }
     Rx(std::string name, std::string param)
         : Operator(name, param) {
+        m_re = new Regex(param);
     }
     explicit Rx(std::string param)
         : Operator("Rx", param) {
+        m_re = new Regex(param);
     }
 
     ~Rx() {
+        delete m_re;
     }
     bool evaluate(Transaction *transaction, Rule *rule,
         const std::string &input) override {
@@ -58,6 +62,9 @@ class Rx : public Operator {
     bool evaluate(Transaction *transaction, Rule *rule,
         const std::string& input,
         std::shared_ptr<RuleMessage> ruleMessage) override;
+
+ private:
+    Regex *m_re;
 };