Add RE2 regex backend

Author: WGH-

src/Makefile.am

@@ -247,7 +247,8 @@ UTILS = \
 
 REGEX = \
 	regex/regex.cc \
-	regex/backend/pcre.cc
+	regex/backend/pcre.cc \
+	regex/backend/re2.cc
 
 
 COLLECTION = \

src/regex/backend/re2.cc

@@ -0,0 +1,98 @@
+/*
+ * ModSecurity, http://www.modsecurity.org/
+ * Copyright (c) 2019
+ *
+ * You may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * If any of the files related to licensing are missing or if you have any
+ * other questions related to licensing please contact Trustwave Holdings, Inc.
+ * directly using the email address security@modsecurity.org.
+ *
+ */
+#include <iostream>
+#include <fstream>
+#include <string>
+#include <list>
+
+#include "src/regex/backend/re2.h"
+#include "src/regex/regex_match.h"
+
+namespace modsecurity {
+namespace regex {
+namespace backend {
+
+#ifdef WITH_RE2
+
+static RE2::Options get_re2_options() {
+    RE2::Options res;
+
+    res.set_dot_nl(true);
+
+    return res;
+}
+
+
+Re2::Re2(const std::string& pattern_)
+    : pattern(pattern_.empty() ? ".*" : pattern_),
+      re(pattern, get_re2_options())
+{
+}
+
+std::list<RegexMatch> Re2::searchAll(const std::string& s) const {
+    std::list<RegexMatch> retList;
+
+    re2::StringPiece subject(s);
+
+    size_t offset = 0;
+    while (offset <= s.size()) {
+        int ngroups = re.NumberOfCapturingGroups() + 1;
+        re2::StringPiece submatches[ngroups];
+
+        if (!re.Match(subject, offset, s.size(), RE2::UNANCHORED,
+            &submatches[0], ngroups)) {
+            break;
+        }
+
+        for (int i = 0; i < ngroups; i++) {
+            // N.B. StringPiece::as_string returns value, not reference
+            auto match_string =  submatches[i].as_string();
+            auto start = &submatches[i][0] - &subject[0];
+            retList.push_front(RegexMatch(std::move(match_string), start));
+        }
+
+        offset = (&submatches[0][0] - &subject[0]) + submatches[0].length();
+        if (submatches[0].size() == 0) {
+            offset++;
+        }
+    }
+
+    return retList;
+}
+
+int Re2::search(const std::string& s, RegexMatch *match) const {
+    re2::StringPiece subject(s);
+    re2::StringPiece submatches[1];
+    if (re.Match(subject, 0, s.size(), RE2::UNANCHORED, &submatches[0], 1)) {
+        // N.B. StringPiece::as_string returns value, not reference
+        auto match_string = submatches[0].as_string();
+        auto start = &submatches[0][0] - &subject[0];
+        *match = RegexMatch(std::move(match_string), start);
+        return 1;
+    } else {
+        return 0;
+    }
+}
+
+int Re2::search(const std::string& s) const {
+    re2::StringPiece subject(s);
+    return re.Match(subject, 0, s.size(), RE2::UNANCHORED, NULL, 0);
+}
+#endif
+
+}  // namespace backend
+}  // namespace regex
+}  // namespace modsecurity
+

src/regex/backend/re2.h

@@ -0,0 +1,57 @@
+/*
+ * ModSecurity, http://www.modsecurity.org/
+ * Copyright (c) 2019
+ *
+ * You may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * If any of the files related to licensing are missing or if you have any
+ * other questions related to licensing please contact Trustwave Holdings, Inc.
+ * directly using the email address security@modsecurity.org.
+ *
+ */
+
+#ifdef WITH_RE2
+#include <re2/re2.h>
+#endif
+
+#include <string>
+#include <list>
+
+#include "src/regex/regex_match.h"
+
+#ifndef SRC_REGEX_BACKEND_RE2_H_
+#define SRC_REGEX_BACKEND_RE2_H_
+
+namespace modsecurity {
+namespace regex {
+namespace backend {
+
+#ifdef WITH_RE2
+
+class Re2 {
+ public:
+    explicit Re2(const std::string& pattern_);
+
+    // RE2 class is not copyable, so neither is this
+    Re2(const Re2&) = delete;
+    Re2& operator=(const Re2&) = delete;
+
+    std::list<RegexMatch> searchAll(const std::string& s) const;
+    int search(const std::string &s, RegexMatch *m) const;
+    int search(const std::string &s) const;
+
+    const std::string pattern;
+ private:
+    const RE2 re;
+};
+
+#endif
+
+}  // namespace backend
+}  // namespace regex
+}  // namespace modsecurity
+
+#endif  // SRC_REGEX_BACKEND_PCRE_H_

src/regex/regex.h

@@ -21,6 +21,7 @@
 #include <list>
 
 #include "src/regex/backend/pcre.h"
+#include "src/regex/backend/re2.h"
 #include "src/regex/regex_match.h"
 
 #ifndef SRC_REGEX_REGEX_H_
@@ -33,7 +34,7 @@ namespace regex {
 #ifdef WITH_PCRE
 using selectedBackend = backend::Pcre;
 #elif WITH_RE2
-//using selectedBackend = backend::Re2;
+using selectedBackend = backend::Re2;
 #else
 #error "no regex backend selected"
 #endif