feat(server): Use mimalloc in SSL calls

Until now, OpenSSL used `malloc()` directly. This PR overrides it to use
mimalloc.

Fixes #2709

src/facade/dragonfly_listener.cc

@@ -156,11 +156,38 @@ bool ConfigureKeepAlive(int fd) {
   return true;
 }
 
+size_t ssl_allocated_bytes = 0;
+
+void* OverriddenSSLMalloc(size_t size, const char* file, int line) {
+  void* res = mi_malloc(size);
+  ssl_allocated_bytes += mi_malloc_usable_size(res);
+  return res;
+}
+
+void* OverriddenSSLRealloc(void* addr, size_t size, const char* file, int line) {
+  size_t prev_size = mi_malloc_usable_size(addr);
+  void* res = mi_realloc(addr, size);
+  ssl_allocated_bytes += mi_malloc_usable_size(res);
+  ssl_allocated_bytes -= prev_size;
+  return res;
+}
+
+void OverriddenSSLFree(void* addr, const char* file, int line) {
+  ssl_allocated_bytes -= mi_malloc_usable_size(addr);
+  mi_free(addr);
+}
+
+std::once_flag g_set_mem_functions_flag;
+
 }  // namespace
 
 Listener::Listener(Protocol protocol, ServiceInterface* si, Role role)
     : service_(si), protocol_(protocol) {
 #ifdef DFLY_USE_SSL
+  call_once(g_set_mem_functions_flag, []() {
+    CRYPTO_set_mem_functions(&OverriddenSSLMalloc, &OverriddenSSLRealloc, &OverriddenSSLFree);
+  });
+
   // Always initialise OpenSSL so we can enable TLS at runtime.
   OPENSSL_init_ssl(OPENSSL_INIT_SSL_DEFAULT, nullptr);
   if (!ReconfigureTLS()) {