Perform RemoveCommentsChar, RemoveComments & ReplaceComments transformations in-place

Author: eduar-hte

src/actions/transformations/remove_comments.cc

@@ -19,41 +19,34 @@
 namespace modsecurity::actions::transformations {
 
 
-bool RemoveComments::transform(std::string &value, const Transaction *trans) const {
-    std::string ret;
-    unsigned char *input;
-
-    input = reinterpret_cast<unsigned char *>
-        (malloc(sizeof(char) * value.length()+1));
-
-    if (input == NULL) {
-        return "";
-    }
-
-    memcpy(input, value.c_str(), value.length()+1);
-
-    uint64_t input_len = value.size();
-    uint64_t i, j, incomment;
+static inline int inplace(std::string &value) {
+    auto input = reinterpret_cast<unsigned char*>(value.data());
+    const auto input_len = value.length();
+    bool changed = false, incomment = false;
+    std::string::size_type i = 0, j = 0;
 
-    i = j = incomment = 0;
     while (i < input_len) {
-        if (incomment == 0) {
+        if (!incomment) {
             if ((input[i] == '/') && (i + 1 < input_len)
                 && (input[i + 1] == '*')) {
-                incomment = 1;
+                incomment = true;
+                changed = true;
                 i += 2;
             } else if ((input[i] == '<') && (i + 1 < input_len)
                 && (input[i + 1] == '!') && (i + 2 < input_len)
                 && (input[i+2] == '-') && (i + 3 < input_len)
                 && (input[i + 3] == '-')) {
-                incomment = 1;
+                incomment = true;
+                changed = true;
                 i += 4;
             } else if ((input[i] == '-') && (i + 1 < input_len)
                 && (input[i + 1] == '-')) {
                 input[i] = ' ';
+                changed = true;
                 break;
             } else if (input[i] == '#') {
                 input[i] = ' ';
+                changed = true;
                 break;
             } else {
                 input[j] = input[i];
@@ -63,15 +56,15 @@ bool RemoveComments::transform(std::string &value, const Transaction *trans) con
         } else {
             if ((input[i] == '*') && (i + 1 < input_len)
                 && (input[i + 1] == '/')) {
-                incomment = 0;
+                incomment = false;
                 i += 2;
                 input[j] = input[i];
                 i++;
                 j++;
             } else if ((input[i] == '-') && (i + 1 < input_len)
                 && (input[i + 1] == '-') && (i + 2 < input_len)
                 && (input[i+2] == '>'))   {
-                incomment = 0;
+                incomment = false;
                 i += 3;
                 input[j] = input[i];
                 i++;
@@ -86,13 +79,14 @@ bool RemoveComments::transform(std::string &value, const Transaction *trans) con
         input[j++] = ' ';
     }
 
-    ret.assign(reinterpret_cast<char *>(input), j);
-    free(input);
-
-    const auto changed = ret != value;
-    value = ret;
+    value.resize(j);
     return changed;
 }
 
 
+bool RemoveComments::transform(std::string &value, const Transaction *trans) const {
+    return inplace(value);
+}
+
+
 }  // namespace modsecurity::actions::transformations

src/actions/transformations/remove_comments_char.cc

@@ -23,43 +23,43 @@ RemoveCommentsChar::RemoveCommentsChar(const std::string &action)
     this->action_kind = 1;
 }
 
-bool RemoveCommentsChar::transform(std::string &val, const Transaction *trans) const {
-    size_t i = 0;
-    std::string transformed_value;
-    transformed_value.reserve(val.size());
+bool RemoveCommentsChar::transform(std::string &value, const Transaction *trans) const {
+    char *d = value.data();
+    const char *s = d;
+    const char *e = s + value.size();
 
-    while (i < val.size()) {
-        if (val.at(i) == '/'
-            && (i+1 < val.size()) && val.at(i+1) == '*') {
-            i += 2;
-        } else if (val.at(i) == '*'
-            && (i+1 < val.size()) && val.at(i+1) == '/') {
-            i += 2;
-        } else if (val.at(i) == '<'
-            && (i+1 < val.size())
-            && val.at(i+1) == '!'
-            && (i+2 < val.size())
-            && val.at(i+2) == '-'
-            && (i+3 < val.size())
-            && val.at(i+3) == '-') {
-            i += 4;
-        } else if (val.at(i) == '-'
-            && (i+1 < val.size()) && val.at(i+1) == '-'
-            && (i+2 < val.size()) && val.at(i+2) == '>') {
-            i += 3;
-        } else if (val.at(i) == '-'
-            && (i+1 < val.size()) && val.at(i+1) == '-') {
-            i += 2;
-        } else if (val.at(i) == '#') {
-            i += 1;
+    while (s < e) {
+        if (*s == '/'
+            && (s+1 < e) && *(s+1) == '*') {
+            s += 2;
+        } else if (*s == '*'
+            && (s+1 < e) && *(s+1) == '/') {
+            s += 2;
+        } else if (*s == '<'
+            && (s+1 < e)
+            && *(s+1) == '!'
+            && (s+2 < e)
+            && *(s+2) == '-'
+            && (s+3 < e)
+            && *(s+3) == '-') {
+            s += 4;
+        } else if (*s == '-'
+            && (s+1 < e) && *(s+1) == '-'
+            && (s+2 < e) && *(s+2) == '>') {
+            s += 3;
+        } else if (*s == '-'
+            && (s+1 < e) && *(s+1) == '-') {
+            s += 2;
+        } else if (*s == '#') {
+            s += 1;
         } else {
-            transformed_value += val.at(i);
-            i++;
+            *d++ = *s++;
         }
     }
 
-    const auto changed = transformed_value != val;
-    val = transformed_value;
+    const auto changed = d != s;
+    const auto new_len = d - value.c_str();
+    value.resize(new_len);
     return changed;
 }
 

src/actions/transformations/replace_comments.cc

@@ -19,36 +19,28 @@
 namespace modsecurity::actions::transformations {
 
 
-ReplaceComments::ReplaceComments(const std::string &action) 
-    : Transformation(action) {
-    this->action_kind = 1;
-}
-
-
-bool ReplaceComments::transform(std::string &value, const Transaction *trans) const {
-    uint64_t i, j, incomment;
-
-    char *input = reinterpret_cast<char *>(
-        malloc(sizeof(char) * value.size() + 1));
-    memcpy(input, value.c_str(), value.size() + 1);
-    input[value.size()] = '\0';
-
-    i = j = incomment = 0;
-    while (i < value.size()) {
-        if (incomment == 0) {
-            if ((input[i] == '/') && (i + 1 < value.size())
+static inline bool inplace(std::string &value) {
+    auto input = reinterpret_cast<unsigned char*>(value.data());
+    const auto input_len = value.length();
+    bool changed = false, incomment = false;
+    std::string::size_type i = 0, j = 0;
+
+    while (i < input_len) {
+        if (!incomment) {
+            if ((input[i] == '/') && (i + 1 < input_len)
                 && (input[i + 1] == '*')) {
-                incomment = 1;
+                incomment = true;
                 i += 2;
+                changed = true;
             } else {
                 input[j] = input[i];
                 i++;
                 j++;
             }
         } else {
-            if ((input[i] == '*') && (i + 1 < value.size())
+            if ((input[i] == '*') && (i + 1 < input_len)
                 && (input[i + 1] == '/')) {
-                incomment = 0;
+                incomment = false;
                 i += 2;
                 input[j] = ' ';
                 j++;
@@ -62,15 +54,19 @@ bool ReplaceComments::transform(std::string &value, const Transaction *trans) co
         input[j++] = ' ';
     }
 
+    value.resize(j);
+    return changed;
+}
 
-    std::string resp;
-    resp.append(reinterpret_cast<char *>(input), j);
 
-    free(input);
+ReplaceComments::ReplaceComments(const std::string &action) 
+    : Transformation(action) {
+    this->action_kind = 1;
+}
 
-    const auto changed = resp != value;
-    value = resp;
-    return changed;
+
+bool ReplaceComments::transform(std::string &value, const Transaction *trans) const {
+    return inplace(value);
 }