quic: always copy stateless reset token

Take ownership of the token value, since the memory for it is allocated
anyway and the buffer size is just 16, i.e. copyable very cheaply.

This makes valgrind stop complaining about a use-after-free error
when running `sequential/test-quic-preferred-address-ipv6`.

PR-URL: #33917
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

src/quic/node_quic_util-inl.h

@@ -287,22 +287,27 @@ bool PreferredAddress::ResolvePreferredAddress(
 StatelessResetToken::StatelessResetToken(
     uint8_t* token,
     const uint8_t* secret,
-    const QuicCID& cid) : token_(token) {
+    const QuicCID& cid) {
   GenerateResetToken(token, secret, cid);
+  memcpy(buf_, token, sizeof(buf_));
 }
 
 StatelessResetToken::StatelessResetToken(
     const uint8_t* secret,
-    const QuicCID& cid)
-    : token_(buf_) {
+    const QuicCID& cid)  {
   GenerateResetToken(buf_, secret, cid);
 }
 
+StatelessResetToken::StatelessResetToken(
+    const uint8_t* token) {
+  memcpy(buf_, token, sizeof(buf_));
+}
+
 std::string StatelessResetToken::ToString() const {
   std::vector<char> dest(NGTCP2_STATELESS_RESET_TOKENLEN * 2 + 1);
   dest[dest.size() - 1] = '\0';
   size_t written = StringBytes::hex_encode(
-      reinterpret_cast<const char*>(token_),
+      reinterpret_cast<const char*>(buf_),
       NGTCP2_STATELESS_RESET_TOKENLEN,
       dest.data(),
       dest.size());
@@ -313,7 +318,7 @@ size_t StatelessResetToken::Hash::operator()(
     const StatelessResetToken& token) const {
   size_t hash = 0;
   for (size_t n = 0; n < NGTCP2_STATELESS_RESET_TOKENLEN; n++)
-    hash ^= std::hash<uint8_t>{}(token.token_[n]) + 0x9e3779b9 +
+    hash ^= std::hash<uint8_t>{}(token.buf_[n]) + 0x9e3779b9 +
             (hash << 6) + (hash >> 2);
   return hash;
 }

src/quic/node_quic_util.h

@@ -386,13 +386,12 @@ class StatelessResetToken : public MemoryRetainer {
       const uint8_t* secret,
       const QuicCID& cid);
 
-  explicit StatelessResetToken(
-      const uint8_t* token)
-      : token_(token) {}
+  explicit inline StatelessResetToken(
+      const uint8_t* token);
 
   inline std::string ToString() const;
 
-  const uint8_t* data() const { return token_; }
+  const uint8_t* data() const { return buf_; }
 
   struct Hash {
     inline size_t operator()(const StatelessResetToken& token) const;
@@ -414,7 +413,6 @@ class StatelessResetToken : public MemoryRetainer {
 
  private:
   uint8_t buf_[NGTCP2_STATELESS_RESET_TOKENLEN]{};
-  const uint8_t* token_;
 };
 
 template <typename T>