fix: Memory leak in normalize_http_method

runtime/fastly/common/normalize_http_method.cpp

@@ -1,44 +1,28 @@
+#include <algorithm>
+#include <cctype>
 #include <string_view>
 
-using namespace std::literals::string_view_literals;
-
 namespace fastly::common {
-namespace {
-inline char *ascii_uppercase(char *str, size_t length) {
-  char *up = reinterpret_cast<char *>(malloc(length + 1));
-  int i = 0;
-  while (i < length) {
-    auto ch = str[i];
-    if (ch >= 'a' && ch <= 'z') {
-      up[i] = ch & ~0x20;
-    } else {
-      up[i] = ch;
-    }
-    i++;
-  }
-  up[i] = '\0';
-  return up;
-}
-} // namespace
 
 // https://fetch.spec.whatwg.org/#concept-method-normalize
 // To normalize a method, if it is a byte-case-insensitive match for `DELETE`, `GET`, `HEAD`,
 // `OPTIONS`, `POST`, or `PUT`, byte-uppercase it.
 bool normalize_http_method(char *method, size_t length) {
-  auto m = std::string_view(method, length);
-  // It's quite likely the method is already uppercased,
-  // so let's check it first before we create a copy of the method to uppercase it.
-  // These have been order by most likely to occur.
-  if (m != "GET"sv && m != "HEAD"sv && m != "OPTIONS"sv && m != "POST"sv && m != "PUT"sv &&
-      m != "DELETE"sv) [[unlikely]] {
-    auto umethod = ascii_uppercase(method, length);
-    if (strcmp(umethod, "GET") == 0 || strcmp(umethod, "HEAD") == 0 ||
-        strcmp(umethod, "OPTIONS") == 0 || strcmp(umethod, "POST") == 0 ||
-        strcmp(umethod, "PUT") == 0 || strcmp(umethod, "DELETE") == 0) {
-      strcpy(method, umethod);
-      return true;
-    }
+  // Ordered by most likely to occur.
+  constexpr std::string_view methods[] = {"GET", "HEAD", "OPTIONS", "POST", "PUT", "DELETE"};
+  std::string_view m(method, length);
+
+  auto iequal = [](unsigned char a, unsigned char b) { return std::toupper(a) == std::toupper(b); };
+
+  auto it = std::ranges::find_if(methods, [&](std::string_view candidate) {
+    return std::ranges::equal(m, candidate, iequal);
+  });
+
+  if (it == std::ranges::end(methods) || *it == m) {
+    return false; // not a recognized method, or already normalized
   }
-  return false;
+
+  std::ranges::copy(*it, method); // copy the already-uppercase canonical form
+  return true;
 }
 } // namespace fastly::common