Use udns instead of c-ares

fix #3226

louloulibs/network/dns_handler.cpp

@@ -1,5 +1,5 @@
 #include <louloulibs.h>
-#ifdef CARES_FOUND
+#ifdef UDNS_FOUND
 
 #include <network/dns_socket_handler.hpp>
 #include <network/dns_handler.hpp>
@@ -7,123 +7,40 @@
 
 #include <utils/timed_events.hpp>
 
-#include <algorithm>
+#include <udns.h>
 
-DNSHandler DNSHandler::instance;
+#include <cstring>
+
+class Resolver;
 
 using namespace std::string_literals;
-DNSHandler::DNSHandler():
-  socket_handlers{},
-  channel{nullptr}
-{
-  int ares_error;
-  if ((ares_error = ::ares_library_init(ARES_LIB_INIT_ALL)) != 0)
-    throw std::runtime_error("Failed to initialize c-ares lib: "s + ares_strerror(ares_error));
-  struct ares_options options = {};
-  // The default timeout values are way too high
-  options.timeout = 1000;
-  options.tries = 3;
-  if ((ares_error = ::ares_init_options(&this->channel,
-                                        &options,
-                                        ARES_OPT_TIMEOUTMS|ARES_OPT_TRIES)) != ARES_SUCCESS)
-    throw std::runtime_error("Failed to initialize c-ares channel: "s + ares_strerror(ares_error));
-}
 
-ares_channel& DNSHandler::get_channel()
+std::unique_ptr<DNSSocketHandler> DNSHandler::socket_handler{};
+
+DNSHandler::DNSHandler(std::shared_ptr<Poller> poller)
 {
-  return this->channel;
+  dns_init(nullptr, 0);
+  const auto socket = dns_open(nullptr);
+  if (socket == -1)
+    throw std::runtime_error("Failed to initialize udns socket: "s + strerror(errno));
+
+  DNSHandler::socket_handler = std::make_unique<DNSSocketHandler>(poller, socket);
 }
 
 void DNSHandler::destroy()
 {
-  this->remove_all_sockets_from_poller();
-  this->socket_handlers.clear();
-  ::ares_destroy(this->channel);
-  ::ares_library_cleanup();
+  DNSHandler::socket_handler.reset(nullptr);
+  dns_close(nullptr);
 }
 
-void DNSHandler::gethostbyname(const std::string& name, ares_host_callback callback,
-                               void* data, int family)
+void DNSHandler::watch()
 {
-  ::ares_gethostbyname(this->channel, name.data(), family,
-                         callback, data);
+  DNSHandler::socket_handler->watch();
 }
 
-void DNSHandler::watch_dns_sockets(std::shared_ptr<Poller>& poller)
+void DNSHandler::unwatch()
 {
-  fd_set readers;
-  fd_set writers;
-
-  FD_ZERO(&readers);
-  FD_ZERO(&writers);
-
-  int ndfs = ::ares_fds(this->channel, &readers, &writers);
-  // For each existing DNS socket, see if we are still supposed to watch it,
-  // if not then erase it
-  this->socket_handlers.erase(
-      std::remove_if(this->socket_handlers.begin(), this->socket_handlers.end(),
-                     [&readers](const auto& dns_socket)
-                     {
-                       return !FD_ISSET(dns_socket->get_socket(), &readers);
-                     }),
-      this->socket_handlers.end());
-
-  for (auto i = 0; i < ndfs; ++i)
-    {
-      bool read = FD_ISSET(i, &readers);
-      bool write = FD_ISSET(i, &writers);
-      // Look for the DNSSocketHandler with this fd
-      auto it = std::find_if(this->socket_handlers.begin(),
-                             this->socket_handlers.end(),
-                             [i](const auto& socket_handler)
-                             {
-        return i == socket_handler->get_socket();
-      });
-      if (!read && !write)      // No need to read or write to it
-        { // If found, erase it and stop watching it because it is not
-          // needed anymore
-          if (it != this->socket_handlers.end())
-            // The socket destructor removes it from the poller
-            this->socket_handlers.erase(it);
-        }
-      else            // We need to write and/or read to it
-        { // If not found, create it because we need to watch it
-          if (it == this->socket_handlers.end())
-            {
-              this->socket_handlers.emplace(this->socket_handlers.begin(),
-                                            std::make_unique<DNSSocketHandler>(poller, *this, i));
-              it = this->socket_handlers.begin();
-            }
-          poller->add_socket_handler(it->get());
-          if (write)
-            poller->watch_send_events(it->get());
-        }
-    }
-  // Cancel previous timer, if any.
-  TimedEventsManager::instance().cancel("DNS timeout");
-  struct timeval tv;
-  struct timeval* tvp;
-  tvp = ::ares_timeout(this->channel, NULL, &tv);
-  if (tvp)
-    {
-      auto future_time = std::chrono::steady_clock::now() + std::chrono::seconds(tvp->tv_sec) + \
-        std::chrono::microseconds(tvp->tv_usec);
-      TimedEventsManager::instance().add_event(TimedEvent(std::move(future_time),
-                                                          [this]()
-             {
-               for (auto& dns_socket_handler: this->socket_handlers)
-                 dns_socket_handler->on_recv();
-             },
-                                                          "DNS timeout"));
-    }
+  DNSHandler::socket_handler->unwatch();
 }
 
-void DNSHandler::remove_all_sockets_from_poller()
-{
-  for (const auto& socket_handler: this->socket_handlers)
-  {
-    socket_handler->remove_from_poller();
-  }
-}
-
-#endif /* CARES_FOUND */
+#endif /* UDNS_FOUND */