Use udns instead of c-ares

fix #3226

7 files changed, 246 insertions, 317 deletions

diff --git a/louloulibs/network/dns_handler.cpp b/louloulibs/network/dns_handler.cpp
index b1807b5..ad0ad38 100644
--- a/louloulibs/network/dns_handler.cpp
+++ b/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()
-{
-  return this->channel;
-}
+std::unique_ptr<DNSSocketHandler> DNSHandler::socket_handler{};
 
-void DNSHandler::destroy()
+DNSHandler::DNSHandler(std::shared_ptr<Poller> poller)
 {
-  this->remove_all_sockets_from_poller();
-  this->socket_handlers.clear();
-  ::ares_destroy(this->channel);
-  ::ares_library_cleanup();
+  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::gethostbyname(const std::string& name, ares_host_callback callback,
-                               void* data, int family)
+void DNSHandler::destroy()
 {
-  ::ares_gethostbyname(this->channel, name.data(), family,
-                         callback, data);
+  DNSHandler::socket_handler.reset(nullptr);
+  dns_close(nullptr);
 }
 
-void DNSHandler::watch_dns_sockets(std::shared_ptr<Poller>& poller)
+void DNSHandler::watch()
 {
-  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->watch();
 }
 
-void DNSHandler::remove_all_sockets_from_poller()
+void DNSHandler::unwatch()
 {
-  for (const auto& socket_handler: this->socket_handlers)
-  {
-    socket_handler->remove_from_poller();
-  }
+  DNSHandler::socket_handler->unwatch();
 }
 
-#endif /* CARES_FOUND */
+#endif /* UDNS_FOUND */
diff --git a/louloulibs/network/dns_handler.hpp b/louloulibs/network/dns_handler.hpp
index 53a7799..0148156 100644
--- a/louloulibs/network/dns_handler.hpp
+++ b/louloulibs/network/dns_handler.hpp
@@ -1,59 +1,37 @@
 #pragma once
 
 #include <louloulibs.h>
-#ifdef CARES_FOUND
+#ifdef UDNS_FOUND
 
-class TCPSocketHandler;
 class Poller;
-class DNSSocketHandler;
 
-# include <ares.h>
-# include <memory>
-# include <string>
-# include <vector>
+#include <network/dns_socket_handler.hpp>
 
-/**
- * Class managing DNS resolution.  It should only be statically instanciated
- * once in SocketHandler.  It manages ares channel and calls various
- * functions of that library.
- */
+#include <string>
+#include <vector>
+#include <memory>
 
 class DNSHandler
 {
-private:
-  DNSHandler();
 public:
+  DNSHandler(std::shared_ptr<Poller> poller);
   ~DNSHandler() = default;
+
   DNSHandler(const DNSHandler&) = delete;
   DNSHandler(DNSHandler&&) = delete;
   DNSHandler& operator=(const DNSHandler&) = delete;
   DNSHandler& operator=(DNSHandler&&) = delete;
 
-  void gethostbyname(const std::string& name, ares_host_callback callback,
-                     void* socket_handler, int family);
-  /**
-   * Call ares_fds to know what fd needs to be watched by the poller, create
-   * or destroy DNSSocketHandlers depending on the result.
-   */
-  void watch_dns_sockets(std::shared_ptr<Poller>& poller);
-  /**
-   * Destroy and stop watching all the DNS sockets. Then de-init the channel
-   * and library.
-   */
   void destroy();
-  void remove_all_sockets_from_poller();
-  ares_channel& get_channel();
 
-  static DNSHandler instance;
+  static void watch();
+  static void unwatch();
 
 private:
   /**
-   * The list of sockets that needs to be watched, according to the last
-   * call to ares_fds.  DNSSocketHandlers are added to it or removed from it
-   * in the watch_dns_sockets() method
+   * Manager for the socket returned by udns, that we need to watch with the poller
    */
-  std::vector<std::unique_ptr<DNSSocketHandler>> socket_handlers;
-  ares_channel channel;
+  static std::unique_ptr<DNSSocketHandler> socket_handler;
 };
 
-#endif /* CARES_FOUND */
+#endif /* UDNS_FOUND */
diff --git a/louloulibs/network/dns_socket_handler.cpp b/louloulibs/network/dns_socket_handler.cpp
index a69f59b..ad744a9 100644
--- a/louloulibs/network/dns_socket_handler.cpp
+++ b/louloulibs/network/dns_socket_handler.cpp
@@ -1,34 +1,27 @@
 #include <louloulibs.h>
-#ifdef CARES_FOUND
+#ifdef UDNS_FOUND
 
 #include <network/dns_socket_handler.hpp>
 #include <network/dns_handler.hpp>
 #include <network/poller.hpp>
 
-#include <ares.h>
+#include <udns.h>
 
 DNSSocketHandler::DNSSocketHandler(std::shared_ptr<Poller> poller,
-                                   DNSHandler& handler,
                                    const socket_t socket):
-  SocketHandler(poller, socket),
-  handler(handler)
+  SocketHandler(poller, socket)
 {
+  poller->add_socket_handler(this);
 }
 
-void DNSSocketHandler::on_recv()
+DNSSocketHandler::~DNSSocketHandler()
 {
-  // always stop watching send and read events. We will re-watch them if the
-  // next call to ares_fds tell us to
-  this->handler.remove_all_sockets_from_poller();
-  ::ares_process_fd(DNSHandler::instance.get_channel(), this->socket, ARES_SOCKET_BAD);
+  this->unwatch();
 }
 
-void DNSSocketHandler::on_send()
+void DNSSocketHandler::on_recv()
 {
-  // always stop watching send and read events. We will re-watch them if the
-  // next call to ares_fds tell us to
-  this->handler.remove_all_sockets_from_poller();
-  ::ares_process_fd(DNSHandler::instance.get_channel(), ARES_SOCKET_BAD, this->socket);
+  dns_ioevent(nullptr, 0);
 }
 
 bool DNSSocketHandler::is_connected() const
@@ -36,10 +29,15 @@ bool DNSSocketHandler::is_connected() const
   return true;
 }
 
-void DNSSocketHandler::remove_from_poller()
+void DNSSocketHandler::unwatch()
 {
   if (this->poller->is_managing_socket(this->socket))
     this->poller->remove_socket_handler(this->socket);
 }
 
-#endif /* CARES_FOUND */
+void DNSSocketHandler::watch()
+{
+  this->poller->add_socket_handler(this);
+}
+
+#endif /* UDNS_FOUND */
diff --git a/louloulibs/network/dns_socket_handler.hpp b/louloulibs/network/dns_socket_handler.hpp
index e3fed0c..e12f145 100644
--- a/louloulibs/network/dns_socket_handler.hpp
+++ b/louloulibs/network/dns_socket_handler.hpp
@@ -1,44 +1,33 @@
 #pragma once
 
 #include <louloulibs.h>
-#ifdef CARES_FOUND
+#ifdef UDNS_FOUND
 
 #include <network/socket_handler.hpp>
-#include <ares.h>
 
 /**
- * Manage a socket returned by ares_fds. We do not create, open or close the
- * socket ourself: this is done by c-ares.  We just call ares_process_fd()
- * with the correct parameters, depending on what can be done on that socket
- * (Poller reported it to be writable or readeable)
+ * Manage the UDP socket provided by udns, we do not create, open or close the
+ * socket ourself: this is done by udns.  We only watch it for readability
  */
-
-class DNSHandler;
-
 class DNSSocketHandler: public SocketHandler
 {
 public:
-  explicit DNSSocketHandler(std::shared_ptr<Poller> poller, DNSHandler& handler, const socket_t socket);
-  ~DNSSocketHandler() = default;
+  explicit DNSSocketHandler(std::shared_ptr<Poller> poller, const socket_t socket);
+  ~DNSSocketHandler();
   DNSSocketHandler(const DNSSocketHandler&) = delete;
   DNSSocketHandler(DNSSocketHandler&&) = delete;
   DNSSocketHandler& operator=(const DNSSocketHandler&) = delete;
   DNSSocketHandler& operator=(DNSSocketHandler&&) = delete;
 
-  /**
-   * Just call dns_process_fd, c-ares will do its work of send()ing or
-   * recv()ing the data it wants on that socket.
-   */
   void on_recv() override final;
-  void on_send() override final;
+
   /**
    * Always true, see the comment for connect()
    */
   bool is_connected() const override final;
-  void remove_from_poller();
 
-private:
-  DNSHandler& handler;
+  void watch();
+  void unwatch();
 };
 
-#endif // CARES_FOUND
+#endif // UDNS_FOUND
diff --git a/louloulibs/network/resolver.cpp b/louloulibs/network/resolver.cpp
index 3847d87..efb0cf0 100644
--- a/louloulibs/network/resolver.cpp
+++ b/louloulibs/network/resolver.cpp
@@ -1,19 +1,32 @@
 #include <network/dns_handler.hpp>
+#include <utils/timed_events.hpp>
 #include <network/resolver.hpp>
 #include <string.h>
 #include <arpa/inet.h>
 #include <netinet/in.h>
+#include <udns.h>
 
+#include <fstream>
 #include <cstdlib>
+#include <sstream>
+#include <chrono>
+#include <map>
 
 using namespace std::string_literals;
 
+static std::map<int, std::string> dns_error_messages {
+    {DNS_E_TEMPFAIL, "Timeout while contacting DNS servers"},
+    {DNS_E_PROTOCOL, "Misformatted DNS reply"},
+    {DNS_E_NXDOMAIN, "Domain name not found"},
+    {DNS_E_NOMEM, "Out of memory"},
+    {DNS_E_BADQUERY, "Misformatted domain name"}
+};
+
 Resolver::Resolver():
-#ifdef CARES_FOUND
+#ifdef UDNS_FOUND
   resolved4(false),
   resolved6(false),
   resolving(false),
-  cares_addrinfo(nullptr),
   port{},
 #endif
   resolved(false),
@@ -26,15 +39,44 @@ void Resolver::resolve(const std::string& hostname, const std::string& port,
 {
   this->error_cb = error_cb;
   this->success_cb = success_cb;
-#ifdef CARES_FOUND
+#ifdef UDNS_FOUND
   this->port = port;
 #endif
 
   this->start_resolving(hostname, port);
 }
 
-#ifdef CARES_FOUND
-void Resolver::start_resolving(const std::string& hostname, const std::string&)
+int Resolver::call_getaddrinfo(const char *name, const char* port, int flags)
+{
+  struct addrinfo hints;
+  memset(&hints, 0, sizeof(struct addrinfo));
+  hints.ai_flags = flags;
+  hints.ai_family = AF_UNSPEC;
+  hints.ai_socktype = SOCK_STREAM;
+  hints.ai_protocol = 0;
+
+  struct addrinfo* addr_res = nullptr;
+  const int res = ::getaddrinfo(name, port,
+                                &hints, &addr_res);
+
+  if (res == 0 && addr_res)
+    {
+      if (!this->addr)
+        this->addr.reset(addr_res);
+      else
+        { // Append this result at the end of the linked list
+          struct addrinfo *rp = this->addr.get();
+          while (rp->ai_next)
+            rp = rp->ai_next;
+          rp->ai_next = addr_res;
+        }
+    }
+
+  return res;
+}
+
+#ifdef UDNS_FOUND
+void Resolver::start_resolving(const std::string& hostname, const std::string& port)
 {
   this->resolving = true;
   this->resolved = false;
@@ -42,48 +84,139 @@ void Resolver::start_resolving(const std::string& hostname, const std::string&)
   this->resolved6 = false;
 
   this->error_msg.clear();
-  this->cares_addrinfo = nullptr;
+  this->addr.reset(nullptr);
 
-  auto hostname4_resolved = [](void* arg, int status, int,
-                                  struct hostent* hostent)
+  // We first try to use it as an IP address directly. We tell getaddrinfo
+  // to NOT use any DNS resolution.
+  if (this->call_getaddrinfo(hostname.data(), port.data(), AI_NUMERICHOST) == 0)
     {
-      Resolver* resolver = static_cast<Resolver*>(arg);
-      resolver->on_hostname4_resolved(status, hostent);
-    };
-  auto hostname6_resolved = [](void* arg, int status, int,
-                                  struct hostent* hostent)
+      this->on_resolved();
+      return;
+    }
+
+  // Then we look into /etc/hosts to translate the given hostname
+  const auto hosts = this->look_in_etc_hosts(hostname);
+  if (!hosts.empty())
+    {
+      for (const auto &host: hosts)
+        this->call_getaddrinfo(host.data(), port.data(), AI_NUMERICHOST);
+      this->on_resolved();
+      return;
+    }
+
+  // And finally, we try a DNS resolution
+  auto hostname6_resolved = [](dns_ctx*, dns_rr_a6* result, void* data)
+  {
+    Resolver* resolver = static_cast<Resolver*>(data);
+    resolver->on_hostname6_resolved(result);
+  };
+
+  auto hostname4_resolved = [](dns_ctx*, dns_rr_a4* result, void* data)
+  {
+    Resolver* resolver = static_cast<Resolver*>(data);
+    resolver->on_hostname4_resolved(result);
+  };
+
+  DNSHandler::watch();
+  auto res = dns_submit_a4(nullptr, hostname.data(), 0, hostname4_resolved, this);
+  if (!res)
+    this->on_hostname4_resolved(nullptr);
+  res = dns_submit_a6(nullptr, hostname.data(), 0, hostname6_resolved, this);
+  if (!res)
+    this->on_hostname6_resolved(nullptr);
+
+  this->start_timer();
+}
+
+void Resolver::start_timer()
+{
+  const auto timeout = dns_timeouts(nullptr, -1, 0);
+  if (timeout < 0)
+    return;
+  TimedEvent event(std::chrono::steady_clock::now() + std::chrono::seconds(timeout), [this]() { this->start_timer(); }, "DNS");
+  TimedEventsManager::instance().add_event(std::move(event));
+}
+
+std::vector<std::string> Resolver::look_in_etc_hosts(const std::string &hostname)
+{
+  std::ifstream hosts("/etc/hosts");
+  std::string line;
+
+  std::vector<std::string> results;
+  while (std::getline(hosts, line))
     {
-      Resolver* resolver = static_cast<Resolver*>(arg);
-      resolver->on_hostname6_resolved(status, hostent);
-    };
-
-  DNSHandler::instance.gethostbyname(hostname, hostname6_resolved,
-                                     this, AF_INET6);
-  DNSHandler::instance.gethostbyname(hostname, hostname4_resolved,
-                                     this, AF_INET);
+      if (line.empty())
+        continue;
+
+      std::string ip;
+      std::istringstream line_stream(line);
+      line_stream >> ip;
+      if (ip.empty() || ip[0] == '#')
+        continue;
+
+      std::string host;
+      while (line_stream >> host && !host.empty() && host[0] != '#')
+        {
+          if (hostname == host)
+            {
+              results.push_back(ip);
+              break;
+            }
+        }
+    }
+  return results;
 }
 
-void Resolver::on_hostname4_resolved(int status, struct hostent* hostent)
+void Resolver::on_hostname4_resolved(dns_rr_a4 *result)
 {
+  if (dns_active(nullptr) == 0)
+    DNSHandler::unwatch();
+
   this->resolved4 = true;
-  if (status == ARES_SUCCESS)
-    this->fill_ares_addrinfo4(hostent);
+
+  const auto status = dns_status(nullptr);
+
+  if (status >= 0 && result)
+    {
+      char buf[INET6_ADDRSTRLEN];
+
+      for (auto i = 0; i < result->dnsa4_nrr; ++i)
+        {
+          inet_ntop(AF_INET, &result->dnsa4_addr[i], buf, sizeof(buf));
+          this->call_getaddrinfo(buf, this->port.data(), AI_NUMERICHOST);
+        }
+    }
   else
-    this->error_msg = ::ares_strerror(status);
+    {
+      const auto error = dns_error_messages.find(status);
+      if (error != end(dns_error_messages))
+        this->error_msg = error->second;
+    }
 
-  if (this->resolved4 && this->resolved6)
+  if (this->resolved6 && this->resolved4)
     this->on_resolved();
 }
 
-void Resolver::on_hostname6_resolved(int status, struct hostent* hostent)
+void Resolver::on_hostname6_resolved(dns_rr_a6 *result)
 {
+  if (dns_active(nullptr) == 0)
+    DNSHandler::unwatch();
+
   this->resolved6 = true;
-  if (status == ARES_SUCCESS)
-    this->fill_ares_addrinfo6(hostent);
-  else
-    this->error_msg = ::ares_strerror(status);
+  char buf[INET6_ADDRSTRLEN];
+
+  const auto status = dns_status(nullptr);
 
-  if (this->resolved4 && this->resolved6)
+  if (status >= 0 && result)
+    {
+      for (auto i = 0; i < result->dnsa6_nrr; ++i)
+        {
+          inet_ntop(AF_INET6, &result->dnsa6_addr[i], buf, sizeof(buf));
+          this->call_getaddrinfo(buf, this->port.data(), AI_NUMERICHOST);
+        }
+    }
+
+  if (this->resolved6 && this->resolved4)
     this->on_resolved();
 }
 
@@ -91,100 +224,26 @@ void Resolver::on_resolved()
 {
   this->resolved = true;
   this->resolving = false;
-  if (!this->cares_addrinfo)
+  if (!this->addr)
     {
       if (this->error_cb)
         this->error_cb(this->error_msg.data());
     }
   else
     {
-      this->addr.reset(this->cares_addrinfo);
       if (this->success_cb)
         this->success_cb(this->addr.get());
     }
 }
 
-void Resolver::fill_ares_addrinfo4(const struct hostent* hostent)
-{
-  struct addrinfo* prev = this->cares_addrinfo;
-  struct in_addr** address = reinterpret_cast<struct in_addr**>(hostent->h_addr_list);
-
-  while (*address)
-    {
-      // Create a new addrinfo list element, and fill it
-      struct addrinfo* current = new struct addrinfo;
-      current->ai_flags = 0;
-      current->ai_family = hostent->h_addrtype;
-      current->ai_socktype = SOCK_STREAM;
-      current->ai_protocol = 0;
-      current->ai_addrlen = sizeof(struct sockaddr_in);
-
-      struct sockaddr_in* ai_addr = new struct sockaddr_in;
-      
-      ai_addr->sin_family = hostent->h_addrtype;
-      ai_addr->sin_port = htons(std::strtoul(this->port.data(), nullptr, 10));
-      ai_addr->sin_addr.s_addr = (*address)->s_addr;
-
-      current->ai_addr = reinterpret_cast<struct sockaddr*>(ai_addr);
-      current->ai_next = nullptr;
-      current->ai_canonname = nullptr;
-
-      current->ai_next = prev;
-      this->cares_addrinfo = current;
-      prev = current;
-      ++address;
-    }
-}
-
-void Resolver::fill_ares_addrinfo6(const struct hostent* hostent)
-{
-  struct addrinfo* prev = this->cares_addrinfo;
-  struct in6_addr** address = reinterpret_cast<struct in6_addr**>(hostent->h_addr_list);
-
-  while (*address)
-    {
-      // Create a new addrinfo list element, and fill it
-      struct addrinfo* current = new struct addrinfo;
-      current->ai_flags = 0;
-      current->ai_family = hostent->h_addrtype;
-      current->ai_socktype = SOCK_STREAM;
-      current->ai_protocol = 0;
-      current->ai_addrlen = sizeof(struct sockaddr_in6);
-
-      struct sockaddr_in6* ai_addr = new struct sockaddr_in6;
-      ai_addr->sin6_family = hostent->h_addrtype;
-      ai_addr->sin6_port = htons(std::strtoul(this->port.data(), nullptr, 10));
-      ::memcpy(ai_addr->sin6_addr.s6_addr, (*address)->s6_addr, sizeof(ai_addr->sin6_addr.s6_addr));
-      ai_addr->sin6_flowinfo = 0;
-      ai_addr->sin6_scope_id = 0;
-
-      current->ai_addr = reinterpret_cast<struct sockaddr*>(ai_addr);
-      current->ai_canonname = nullptr;
-
-      current->ai_next = prev;
-      this->cares_addrinfo = current;
-      prev = current;
-      ++address;
-    }
-}
-
-#else  // ifdef CARES_FOUND
+#else  // ifdef UDNS_FOUND
 
 void Resolver::start_resolving(const std::string& hostname, const std::string& port)
 {
   // If the resolution fails, the addr will be unset
   this->addr.reset(nullptr);
 
-  struct addrinfo hints;
-  memset(&hints, 0, sizeof(struct addrinfo));
-  hints.ai_flags = 0;
-  hints.ai_family = AF_UNSPEC;
-  hints.ai_socktype = SOCK_STREAM;
-  hints.ai_protocol = 0;
-
-  struct addrinfo* addr_res = nullptr;
-  const int res = ::getaddrinfo(hostname.data(), port.data(),
-                                &hints, &addr_res);
+  const auto res = this->call_getaddrinfo(hostname.data(), port.data(), 0);
 
   this->resolved = true;
 
@@ -196,12 +255,11 @@ void Resolver::start_resolving(const std::string& hostname, const std::string& p
     }
   else
     {
-      this->addr.reset(addr_res);
       if (this->success_cb)
         this->success_cb(this->addr.get());
     }
 }
-#endif  // ifdef CARES_FOUND
+#endif  // ifdef UDNS_FOUND
 
 std::string addr_to_string(const struct addrinfo* rp)
 {
diff --git a/louloulibs/network/resolver.hpp b/louloulibs/network/resolver.hpp
index 7365f93..f516da5 100644
--- a/louloulibs/network/resolver.hpp
+++ b/louloulibs/network/resolver.hpp
@@ -1,38 +1,31 @@
 #pragma once
 
-
 #include "louloulibs.h"
 
 #include <functional>
+#include <vector>
 #include <memory>
 #include <string>
 
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netdb.h>
+#include <udns.h>
 
 class AddrinfoDeleter
 {
  public:
   void operator()(struct addrinfo* addr)
   {
-#ifdef CARES_FOUND
-    while (addr)
-      {
-        delete addr->ai_addr;
-        auto next = addr->ai_next;
-        delete addr;
-        addr = next;
-      }
-#else
     freeaddrinfo(addr);
-#endif
   }
 };
 
+
 class Resolver
 {
 public:
+
   using ErrorCallbackType = std::function<void(const char*)>;
   using SuccessCallbackType = std::function<void(const struct addrinfo*)>;
 
@@ -45,7 +38,7 @@ public:
 
   bool is_resolving() const
   {
-#ifdef CARES_FOUND
+#ifdef UDNS_FOUND
     return this->resolving;
 #else
     return false;
@@ -68,11 +61,10 @@ public:
 
   void clear()
   {
-#ifdef CARES_FOUND
+#ifdef UDNS_FOUND
     this->resolved6 = false;
     this->resolved4 = false;
     this->resolving = false;
-    this->cares_addrinfo = nullptr;
     this->port.clear();
 #endif
     this->resolved = false;
@@ -85,12 +77,18 @@ public:
 
 private:
   void start_resolving(const std::string& hostname, const std::string& port);
-#ifdef CARES_FOUND
-  void on_hostname4_resolved(int status, struct hostent* hostent);
-  void on_hostname6_resolved(int status, struct hostent* hostent);
+  std::vector<std::string> look_in_etc_hosts(const std::string& hostname);
+  /**
+   * Call getaddrinfo() on the given hostname or IP, and append the result
+   * to our internal addrinfo list. Return getaddrinfo()’s return value.
+   */
+  int call_getaddrinfo(const char* name, const char* port, int flags);
+
+#ifdef UDNS_FOUND
+  void on_hostname4_resolved(dns_rr_a4 *result);
+  void on_hostname6_resolved(dns_rr_a6 *result);
 
-  void fill_ares_addrinfo4(const struct hostent* hostent);
-  void fill_ares_addrinfo6(const struct hostent* hostent);
+  void start_timer();
 
   void on_resolved();
 
@@ -99,14 +97,6 @@ private:
 
   bool resolving;
 
-  /**
-   * When using c-ares to resolve the host asynchronously, we need the
-   * c-ares callbacks to fill a structure (a struct addrinfo, for
-   * compatibility with getaddrinfo and the rest of the code that works when
-   * c-ares is not used) with all returned values (for example an IPv6 and
-   * an IPv4). The pointer is given to the unique_ptr to manage its lifetime.
-   */
-  struct addrinfo* cares_addrinfo;
   std::string port;
 
 #endif
@@ -117,7 +107,6 @@ private:
   bool resolved;
   std::string error_msg;
 
-
   std::unique_ptr<struct addrinfo, AddrinfoDeleter> addr;
 
   ErrorCallbackType error_cb;
diff --git a/louloulibs/network/tcp_client_socket_handler.cpp b/louloulibs/network/tcp_client_socket_handler.cpp
index 7f21e3f..4e6445c 100644
--- a/louloulibs/network/tcp_client_socket_handler.cpp
+++ b/louloulibs/network/tcp_client_socket_handler.cpp
@@ -79,7 +79,7 @@ void TCPClientSocketHandler::connect(const std::string& address, const std::stri
 
   if (!this->connecting)
     {
-      // Get the addrinfo from getaddrinfo (or ares_gethostbyname), only if
+      // Get the addrinfo from getaddrinfo (or using udns), only if
       // this is the first call of this function.
       if (!this->resolver.is_resolved())
         {
@@ -103,8 +103,8 @@ void TCPClientSocketHandler::connect(const std::string& address, const std::stri
         }
       else
         {
-          // The c-ares resolved the hostname and the available addresses
-          // where saved in the cares_addrinfo linked list. Now, just use
+          // The DNS resolver resolved the hostname and the available addresses
+          // where saved in the addrinfo linked list. Now, just use
           // this list to try to connect.
           addr_res = this->resolver.get_result().get();
           if (!addr_res)