louloulibs is directly included, instead of being a submodule

Because this is a nightmare to manage

10 files changed, 1513 insertions, 0 deletions

diff --git a/louloulibs b/louloulibs
deleted file mode 160000
-Subproject 0f3c1183e2bf0941ae2bffd3f31577bce4f3001
diff --git a/louloulibs/network/dns_handler.cpp b/louloulibs/network/dns_handler.cpp
new file mode 100644
index 0000000..ec53683
--- /dev/null
+++ b/louloulibs/network/dns_handler.cpp
@@ -0,0 +1,112 @@
+#include <louloulibs.h>
+#ifdef CARES_FOUND
+
+#include <network/dns_socket_handler.hpp>
+#include <network/tcp_socket_handler.hpp>
+#include <network/dns_handler.hpp>
+#include <network/poller.hpp>
+
+#include <algorithm>
+#include <stdexcept>
+
+DNSHandler DNSHandler::instance;
+
+using namespace std::string_literals;
+
+void on_hostname4_resolved(void* arg, int status, int, struct hostent* hostent)
+{
+  TCPSocketHandler* socket_handler = static_cast<TCPSocketHandler*>(arg);
+  socket_handler->on_hostname4_resolved(status, hostent);
+}
+
+void on_hostname6_resolved(void* arg, int status, int, struct hostent* hostent)
+{
+  TCPSocketHandler* socket_handler = static_cast<TCPSocketHandler*>(arg);
+  socket_handler->on_hostname6_resolved(status, hostent);
+}
+
+DNSHandler::DNSHandler()
+{
+  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));
+  if ((ares_error = ::ares_init(&this->channel)) != 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;
+}
+
+void DNSHandler::destroy()
+{
+  this->socket_handlers.clear();
+  ::ares_destroy(this->channel);
+  ::ares_library_cleanup();
+}
+
+void DNSHandler::gethostbyname(const std::string& name,
+                               TCPSocketHandler* socket_handler, int family)
+{
+  socket_handler->free_cares_addrinfo();
+  if (family == AF_INET)
+    ::ares_gethostbyname(this->channel, name.data(), family,
+                         &::on_hostname4_resolved, socket_handler);
+  else
+    ::ares_gethostbyname(this->channel, name.data(), family,
+                         &::on_hostname6_resolved, socket_handler);
+}
+
+void DNSHandler::watch_dns_sockets(std::shared_ptr<Poller>& poller)
+{
+  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_front(std::make_unique<DNSSocketHandler>(poller, i));
+              it = this->socket_handlers.begin();
+            }
+          poller->add_socket_handler(it->get());
+          if (write)
+            poller->watch_send_events(it->get());
+        }
+    }
+}
+
+#endif /* CARES_FOUND */
diff --git a/louloulibs/network/dns_handler.hpp b/louloulibs/network/dns_handler.hpp
new file mode 100644
index 0000000..a515f52
--- /dev/null
+++ b/louloulibs/network/dns_handler.hpp
@@ -0,0 +1,62 @@
+#ifndef DNS_HANDLER_HPP_INCLUDED
+#define DNS_HANDLER_HPP_INCLUDED
+
+#include <louloulibs.h>
+#ifdef CARES_FOUND
+
+class TCPSocketHandler;
+class Poller;
+class DNSSocketHandler;
+
+# include <ares.h>
+# include <memory>
+# include <string>
+# include <list>
+
+void on_hostname4_resolved(void* arg, int status, int, struct hostent* hostent);
+void on_hostname6_resolved(void* arg, int status, int, struct hostent* hostent);
+
+/**
+ * Class managing DNS resolution.  It should only be statically instanciated
+ * once in SocketHandler.  It manages ares channel and calls various
+ * functions of that library.
+ */
+
+class DNSHandler
+{
+public:
+  DNSHandler();
+  ~DNSHandler() = default;
+  void gethostbyname(const std::string& name, TCPSocketHandler* 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();
+  ares_channel& get_channel();
+
+  static DNSHandler instance;
+
+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
+   */
+  std::list<std::unique_ptr<DNSSocketHandler>> socket_handlers;
+  ares_channel channel;
+
+  DNSHandler(const DNSHandler&) = delete;
+  DNSHandler(DNSHandler&&) = delete;
+  DNSHandler& operator=(const DNSHandler&) = delete;
+  DNSHandler& operator=(DNSHandler&&) = delete;
+};
+
+#endif /* CARES_FOUND */
+#endif /* DNS_HANDLER_HPP_INCLUDED */
diff --git a/louloulibs/network/dns_socket_handler.cpp b/louloulibs/network/dns_socket_handler.cpp
new file mode 100644
index 0000000..124c9b2
--- /dev/null
+++ b/louloulibs/network/dns_socket_handler.cpp
@@ -0,0 +1,45 @@
+#include <louloulibs.h>
+#ifdef CARES_FOUND
+
+#include <network/dns_socket_handler.hpp>
+#include <network/dns_handler.hpp>
+#include <network/poller.hpp>
+
+#include <ares.h>
+
+DNSSocketHandler::DNSSocketHandler(std::shared_ptr<Poller> poller,
+                                   const socket_t socket):
+  SocketHandler(poller, socket)
+{
+}
+
+DNSSocketHandler::~DNSSocketHandler()
+{
+}
+
+void DNSSocketHandler::connect()
+{
+}
+
+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->poller->remove_socket_handler(this->socket);
+  ::ares_process_fd(DNSHandler::instance.get_channel(), this->socket, ARES_SOCKET_BAD);
+}
+
+void DNSSocketHandler::on_send()
+{
+  // always stop watching send and read events. We will re-watch them if the
+  // next call to ares_fds tell us to
+  this->poller->remove_socket_handler(this->socket);
+  ::ares_process_fd(DNSHandler::instance.get_channel(), ARES_SOCKET_BAD, this->socket);
+}
+
+bool DNSSocketHandler::is_connected() const
+{
+  return true;
+}
+
+#endif /* CARES_FOUND */
diff --git a/louloulibs/network/dns_socket_handler.hpp b/louloulibs/network/dns_socket_handler.hpp
new file mode 100644
index 0000000..ad119e1
--- /dev/null
+++ b/louloulibs/network/dns_socket_handler.hpp
@@ -0,0 +1,46 @@
+#ifndef DNS_SOCKET_HANDLER_HPP
+# define DNS_SOCKET_HANDLER_HPP
+
+#include <louloulibs.h>
+#ifdef CARES_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)
+ */
+
+class DNSSocketHandler: public SocketHandler
+{
+public:
+  explicit DNSSocketHandler(std::shared_ptr<Poller> poller, const socket_t socket);
+  ~DNSSocketHandler();
+  /**
+   * 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;
+  /**
+   * Do nothing, because we are always considered to be connected, since the
+   * connection is done by c-ares and not by us.
+   */
+  void connect() override final;
+  /**
+   * Always true, see the comment for connect()
+   */
+  bool is_connected() const override final;
+
+private:
+  DNSSocketHandler(const DNSSocketHandler&) = delete;
+  DNSSocketHandler(DNSSocketHandler&&) = delete;
+  DNSSocketHandler& operator=(const DNSSocketHandler&) = delete;
+  DNSSocketHandler& operator=(DNSSocketHandler&&) = delete;
+};
+
+#endif // CARES_FOUND
+#endif // DNS_SOCKET_HANDLER_HPP
diff --git a/louloulibs/network/poller.cpp b/louloulibs/network/poller.cpp
new file mode 100644
index 0000000..329e1c8
--- /dev/null
+++ b/louloulibs/network/poller.cpp
@@ -0,0 +1,225 @@
+#include <network/poller.hpp>
+#include <logger/logger.hpp>
+#include <utils/timed_events.hpp>
+
+#include <assert.h>
+#include <errno.h>
+#include <stdio.h>
+#include <signal.h>
+
+#include <cstring>
+#include <iostream>
+#include <stdexcept>
+
+Poller::Poller()
+{
+#if POLLER == POLL
+  this->nfds = 0;
+#elif POLLER == EPOLL
+  this->epfd = ::epoll_create1(0);
+  if (this->epfd == -1)
+    {
+      log_error("epoll failed: " << strerror(errno));
+      throw std::runtime_error("Could not create epoll instance");
+    }
+#endif
+}
+
+Poller::~Poller()
+{
+}
+
+void Poller::add_socket_handler(SocketHandler* socket_handler)
+{
+  // Don't do anything if the socket is already managed
+  const auto it = this->socket_handlers.find(socket_handler->get_socket());
+  if (it != this->socket_handlers.end())
+    return ;
+
+  this->socket_handlers.emplace(socket_handler->get_socket(), socket_handler);
+
+  // We always watch all sockets for receive events
+#if POLLER == POLL
+  this->fds[this->nfds].fd = socket_handler->get_socket();
+  this->fds[this->nfds].events = POLLIN;
+  this->nfds++;
+#endif
+#if POLLER == EPOLL
+  struct epoll_event event = {EPOLLIN, {socket_handler}};
+  const int res = ::epoll_ctl(this->epfd, EPOLL_CTL_ADD, socket_handler->get_socket(), &event);
+  if (res == -1)
+    {
+      log_error("epoll_ctl failed: " << strerror(errno));
+      throw std::runtime_error("Could not add socket to epoll");
+    }
+#endif
+}
+
+void Poller::remove_socket_handler(const socket_t socket)
+{
+  const auto it = this->socket_handlers.find(socket);
+  if (it == this->socket_handlers.end())
+    throw std::runtime_error("Trying to remove a SocketHandler that is not managed");
+  this->socket_handlers.erase(it);
+
+#if POLLER == POLL
+  for (size_t i = 0; i < this->nfds; i++)
+    {
+      if (this->fds[i].fd == socket)
+        {
+          // Move all subsequent pollfd by one on the left, erasing the
+          // value of the one we remove
+          for (size_t j = i; j < this->nfds - 1; ++j)
+            {
+              this->fds[j].fd = this->fds[j+1].fd;
+              this->fds[j].events= this->fds[j+1].events;
+            }
+          this->nfds--;
+        }
+    }
+#elif POLLER == EPOLL
+  const int res = ::epoll_ctl(this->epfd, EPOLL_CTL_DEL, socket, nullptr);
+  if (res == -1)
+    {
+      log_error("epoll_ctl failed: " << strerror(errno));
+      throw std::runtime_error("Could not remove socket from epoll");
+    }
+#endif
+}
+
+void Poller::watch_send_events(SocketHandler* socket_handler)
+{
+#if POLLER == POLL
+  for (size_t i = 0; i <= this->nfds; ++i)
+    {
+      if (this->fds[i].fd == socket_handler->get_socket())
+        {
+          this->fds[i].events = POLLIN|POLLOUT;
+          return;
+        }
+    }
+  throw std::runtime_error("Cannot watch a non-registered socket for send events");
+#elif POLLER == EPOLL
+  struct epoll_event event = {EPOLLIN|EPOLLOUT, {socket_handler}};
+  const int res = ::epoll_ctl(this->epfd, EPOLL_CTL_MOD, socket_handler->get_socket(), &event);
+  if (res == -1)
+    {
+      log_error("epoll_ctl failed: " << strerror(errno));
+      throw std::runtime_error("Could not modify socket flags in epoll");
+    }
+#endif
+}
+
+void Poller::stop_watching_send_events(SocketHandler* socket_handler)
+{
+#if POLLER == POLL
+  for (size_t i = 0; i <= this->nfds; ++i)
+    {
+      if (this->fds[i].fd == socket_handler->get_socket())
+        {
+          this->fds[i].events = POLLIN;
+          return;
+        }
+    }
+  throw std::runtime_error("Cannot watch a non-registered socket for send events");
+#elif POLLER == EPOLL
+  struct epoll_event event = {EPOLLIN, {socket_handler}};
+  const int res = ::epoll_ctl(this->epfd, EPOLL_CTL_MOD, socket_handler->get_socket(), &event);
+  if (res == -1)
+    {
+      log_error("epoll_ctl failed: " << strerror(errno));
+      throw std::runtime_error("Could not modify socket flags in epoll");
+    }
+#endif
+}
+
+int Poller::poll(const std::chrono::milliseconds& timeout)
+{
+  if (this->socket_handlers.empty() && timeout == utils::no_timeout)
+    return -1;
+#if POLLER == POLL
+  // Convert our nice timeout into this ugly struct
+  struct timespec timeout_ts;
+  struct timespec* timeout_tsp;
+  if (timeout > 0s)
+    {
+      auto seconds = std::chrono::duration_cast<std::chrono::seconds>(timeout);
+      timeout_ts.tv_sec = seconds.count();
+      timeout_ts.tv_nsec = std::chrono::duration_cast<std::chrono::nanoseconds>(timeout - seconds).count();
+      timeout_tsp = &timeout_ts;
+    }
+  else
+    timeout_tsp = nullptr;
+
+  // Unblock all signals, only during the ppoll call
+  sigset_t empty_signal_set;
+  sigemptyset(&empty_signal_set);
+  int nb_events = ::ppoll(this->fds, this->nfds, timeout_tsp,
+                          &empty_signal_set);
+  if (nb_events < 0)
+    {
+      if (errno == EINTR)
+        return true;
+      log_error("poll failed: " << strerror(errno));
+      throw std::runtime_error("Poll failed");
+    }
+  // We cannot possibly have more ready events than the number of fds we are
+  // watching
+  assert(static_cast<unsigned int>(nb_events) <= this->nfds);
+  for (size_t i = 0; i <= this->nfds && nb_events != 0; ++i)
+    {
+      if (this->fds[i].revents == 0)
+        continue;
+      else if (this->fds[i].revents & POLLIN)
+        {
+          auto socket_handler = this->socket_handlers.at(this->fds[i].fd);
+          socket_handler->on_recv();
+          nb_events--;
+        }
+      else if (this->fds[i].revents & POLLOUT)
+        {
+          auto socket_handler = this->socket_handlers.at(this->fds[i].fd);
+          if (socket_handler->is_connected())
+            socket_handler->on_send();
+          else
+            socket_handler->connect();
+          nb_events--;
+        }
+    }
+  return 1;
+#elif POLLER == EPOLL
+  static const size_t max_events = 12;
+  struct epoll_event revents[max_events];
+  // Unblock all signals, only during the epoll_pwait call
+  sigset_t empty_signal_set;
+  sigemptyset(&empty_signal_set);
+  const int nb_events = ::epoll_pwait(this->epfd, revents, max_events, timeout.count(),
+                                      &empty_signal_set);
+  if (nb_events == -1)
+    {
+      if (errno == EINTR)
+        return 0;
+      log_error("epoll wait: " << strerror(errno));
+      throw std::runtime_error("Epoll_wait failed");
+    }
+  for (int i = 0; i < nb_events; ++i)
+    {
+      auto socket_handler = static_cast<SocketHandler*>(revents[i].data.ptr);
+      if (revents[i].events & EPOLLIN)
+        socket_handler->on_recv();
+      else if (revents[i].events & EPOLLOUT)
+        {
+          if (socket_handler->is_connected())
+            socket_handler->on_send();
+          else
+            socket_handler->connect();
+        }
+    }
+  return nb_events;
+#endif
+}
+
+size_t Poller::size() const
+{
+  return this->socket_handlers.size();
+}
diff --git a/louloulibs/network/poller.hpp b/louloulibs/network/poller.hpp
new file mode 100644
index 0000000..de0cb48
--- /dev/null
+++ b/louloulibs/network/poller.hpp
@@ -0,0 +1,95 @@
+#ifndef POLLER_INCLUDED
+# define POLLER_INCLUDED
+
+#include <network/socket_handler.hpp>
+
+#include <unordered_map>
+#include <memory>
+#include <chrono>
+
+#define POLL 1
+#define EPOLL 2
+#define KQUEUE 3
+#include <louloulibs.h>
+#ifndef POLLER
+ #define POLLER POLL
+#endif
+
+#if POLLER == POLL
+ #include <poll.h>
+ #define MAX_POLL_FD_NUMBER 4096
+#elif POLLER == EPOLL
+  #include <sys/epoll.h>
+#else
+  #error Invalid POLLER value
+#endif
+
+/**
+ * We pass some SocketHandlers to this Poller, which uses
+ * poll/epoll/kqueue/select etc to wait for events on these SocketHandlers,
+ * and call the callbacks when event occurs.
+ *
+ * TODO: support these pollers:
+ * - kqueue(2)
+ */
+
+class Poller
+{
+public:
+  explicit Poller();
+  ~Poller();
+  /**
+   * Add a SocketHandler to be monitored by this Poller. All receive events
+   * are always automatically watched.
+   */
+  void add_socket_handler(SocketHandler* socket_handler);
+  /**
+   * Remove (and stop managing) a SocketHandler, designated by the given socket_t.
+   */
+  void remove_socket_handler(const socket_t socket);
+  /**
+   * Signal the poller that he needs to watch for send events for the given
+   * SocketHandler.
+   */
+  void watch_send_events(SocketHandler* socket_handler);
+  /**
+   * Signal the poller that he needs to stop watching for send events for
+   * this SocketHandler.
+   */
+  void stop_watching_send_events(SocketHandler* socket_handler);
+  /**
+   * Wait for all watched events, and call the SocketHandlers' callbacks
+   * when one is ready.  Returns if nothing happened before the provided
+   * timeout.  If the timeout is 0, it waits forever.  If there is no
+   * watched event, returns -1 immediately, ignoring the timeout value.
+   * Otherwise, returns the number of event handled. If 0 is returned this
+   * means that we were interrupted by a signal, or the timeout occured.
+   */
+  int poll(const std::chrono::milliseconds& timeout);
+  /**
+   * Returns the number of SocketHandlers managed by the poller.
+   */
+  size_t size() const;
+
+private:
+  /**
+   * A "list" of all the SocketHandlers that we manage, indexed by socket,
+   * because that's what is returned by select/poll/etc when an event
+   * occures.
+   */
+  std::unordered_map<socket_t, SocketHandler*> socket_handlers;
+
+#if POLLER == POLL
+  struct pollfd fds[MAX_POLL_FD_NUMBER];
+  nfds_t nfds;
+#elif POLLER == EPOLL
+  int epfd;
+#endif
+
+  Poller(const Poller&) = delete;
+  Poller(Poller&&) = delete;
+  Poller& operator=(const Poller&) = delete;
+  Poller& operator=(Poller&&) = delete;
+};
+
+#endif // POLLER_INCLUDED
diff --git a/louloulibs/network/socket_handler.hpp b/louloulibs/network/socket_handler.hpp
new file mode 100644
index 0000000..d01ac5d
--- /dev/null
+++ b/louloulibs/network/socket_handler.hpp
@@ -0,0 +1,45 @@
+#ifndef SOCKET_HANDLER_HPP
+# define SOCKET_HANDLER_HPP
+
+#include <louloulibs.h>
+#include <memory>
+
+class Poller;
+
+typedef int socket_t;
+
+class SocketHandler
+{
+public:
+  explicit SocketHandler(std::shared_ptr<Poller> poller, const socket_t socket):
+    poller(poller),
+    socket(socket)
+  {}
+  virtual ~SocketHandler() {}
+  virtual void on_recv() = 0;
+  virtual void on_send() = 0;
+  virtual void connect() = 0;
+  virtual bool is_connected() const = 0;
+
+  socket_t get_socket() const
+  { return this->socket; }
+
+protected:
+  /**
+   * A pointer to the poller that manages us, because we need to communicate
+   * with it.
+   */
+  std::shared_ptr<Poller> poller;
+  /**
+   * The handled socket.
+   */
+  socket_t socket;
+
+private:
+  SocketHandler(const SocketHandler&) = delete;
+  SocketHandler(SocketHandler&&) = delete;
+  SocketHandler& operator=(const SocketHandler&) = delete;
+  SocketHandler& operator=(SocketHandler&&) = delete;
+};
+
+#endif // SOCKET_HANDLER_HPP
diff --git a/louloulibs/network/tcp_socket_handler.cpp b/louloulibs/network/tcp_socket_handler.cpp
new file mode 100644
index 0000000..f647b86
--- /dev/null
+++ b/louloulibs/network/tcp_socket_handler.cpp
@@ -0,0 +1,590 @@
+#include <network/tcp_socket_handler.hpp>
+#include <network/dns_handler.hpp>
+
+#include <utils/timed_events.hpp>
+#include <utils/scopeguard.hpp>
+#include <network/poller.hpp>
+
+#include <logger/logger.hpp>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <stdexcept>
+#include <unistd.h>
+#include <errno.h>
+#include <netdb.h>
+#include <cstring>
+#include <fcntl.h>
+
+#include <iostream>
+
+#ifdef BOTAN_FOUND
+# include <botan/hex.h>
+
+Botan::AutoSeeded_RNG TCPSocketHandler::rng;
+Permissive_Credentials_Manager TCPSocketHandler::credential_manager;
+Botan::TLS::Policy TCPSocketHandler::policy;
+Botan::TLS::Session_Manager_In_Memory TCPSocketHandler::session_manager(TCPSocketHandler::rng);
+
+#endif
+
+#ifndef UIO_FASTIOV
+# define UIO_FASTIOV 8
+#endif
+
+using namespace std::string_literals;
+using namespace std::chrono_literals;
+
+namespace ph = std::placeholders;
+
+TCPSocketHandler::TCPSocketHandler(std::shared_ptr<Poller> poller):
+  SocketHandler(poller, -1),
+  use_tls(false),
+  connected(false),
+  connecting(false)
+#ifdef CARES_FOUND
+  ,resolving(false),
+  resolved(false),
+  resolved4(false),
+  resolved6(false),
+  cares_addrinfo(nullptr),
+  cares_error()
+#endif
+{}
+
+TCPSocketHandler::~TCPSocketHandler()
+{
+#ifdef CARES_FOUND
+  this->free_cares_addrinfo();
+#endif
+}
+
+void TCPSocketHandler::init_socket(const struct addrinfo* rp)
+{
+  if ((this->socket = ::socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol)) == -1)
+    throw std::runtime_error("Could not create socket: "s + strerror(errno));
+  int optval = 1;
+  if (::setsockopt(this->socket, SOL_SOCKET, SO_KEEPALIVE, &optval, sizeof(optval)) == -1)
+    log_warning("Failed to enable TCP keepalive on socket: " << strerror(errno));
+  // Set the socket on non-blocking mode.  This is useful to receive a EAGAIN
+  // error when connect() would block, to not block the whole process if a
+  // remote is not responsive.
+  const int existing_flags = ::fcntl(this->socket, F_GETFL, 0);
+  if ((existing_flags == -1) ||
+      (::fcntl(this->socket, F_SETFL, existing_flags | O_NONBLOCK) == -1))
+    throw std::runtime_error("Could not initialize socket: "s + strerror(errno));
+}
+
+void TCPSocketHandler::connect(const std::string& address, const std::string& port, const bool tls)
+{
+  this->address = address;
+  this->port = port;
+  this->use_tls = tls;
+
+  utils::ScopeGuard sg;
+
+  struct addrinfo* addr_res;
+
+  if (!this->connecting)
+    {
+      // Get the addrinfo from getaddrinfo (or ares_gethostbyname), only if
+      // this is the first call of this function.
+#ifdef CARES_FOUND
+      if (!this->resolved)
+        {
+          log_info("Trying to connect to " << address << ":" << port);
+          // Start the asynchronous process of resolving the hostname. Once
+          // the addresses have been found and `resolved` has been set to true
+          // (but connecting will still be false), TCPSocketHandler::connect()
+          // needs to be called, again.
+          this->resolving = true;
+          DNSHandler::instance.gethostbyname(address, this, AF_INET6);
+          DNSHandler::instance.gethostbyname(address, this, AF_INET);
+          return;
+        }
+      else
+        {
+          // The c-ares resolved the hostname and the available addresses
+          // where saved in the cares_addrinfo linked list. Now, just use
+          // this list to try to connect.
+          addr_res = this->cares_addrinfo;
+          if (!addr_res)
+            {
+              this->close();
+              this->on_connection_failed(this->cares_error);
+              return ;
+            }
+        }
+#else
+      log_info("Trying to connect to " << address << ":" << port);
+      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;
+
+      const int res = ::getaddrinfo(address.c_str(), port.c_str(), &hints, &addr_res);
+
+      if (res != 0)
+        {
+          log_warning("getaddrinfo failed: "s + gai_strerror(res));
+          this->close();
+          this->on_connection_failed(gai_strerror(res));
+          return ;
+        }
+      // Make sure the alloced structure is always freed at the end of the
+      // function
+      sg.add_callback([&addr_res](){ freeaddrinfo(addr_res); });
+#endif
+    }
+  else
+    { // This function is called again, use the saved addrinfo structure,
+      // instead of re-doing the whole getaddrinfo process.
+      addr_res = &this->addrinfo;
+    }
+
+  for (struct addrinfo* rp = addr_res; rp; rp = rp->ai_next)
+    {
+      if (!this->connecting)
+        {
+          try {
+            this->init_socket(rp);
+          }
+          catch (const std::runtime_error& error) {
+            log_error("Failed to init socket: " << error.what());
+            break;
+          }
+        }
+      if (::connect(this->socket, rp->ai_addr, rp->ai_addrlen) == 0
+          || errno == EISCONN)
+        {
+          log_info("Connection success.");
+          TimedEventsManager::instance().cancel("connection_timeout"s +
+                                                std::to_string(this->socket));
+          this->poller->add_socket_handler(this);
+          this->connected = true;
+          this->connecting = false;
+#ifdef BOTAN_FOUND
+          if (this->use_tls)
+            this->start_tls();
+#endif
+          this->on_connected();
+          return ;
+        }
+      else if (errno == EINPROGRESS || errno == EALREADY)
+        {   // retry this process later, when the socket
+            // is ready to be written on.
+          this->connecting = true;
+          this->poller->add_socket_handler(this);
+          this->poller->watch_send_events(this);
+          // Save the addrinfo structure, to use it on the next call
+          this->ai_addrlen = rp->ai_addrlen;
+          memcpy(&this->ai_addr, rp->ai_addr, this->ai_addrlen);
+          memcpy(&this->addrinfo, rp, sizeof(struct addrinfo));
+          this->addrinfo.ai_addr = reinterpret_cast<struct sockaddr*>(&this->ai_addr);
+          this->addrinfo.ai_next = nullptr;
+          // If the connection has not succeeded or failed in 5s, we consider
+          // it to have failed
+          TimedEventsManager::instance().add_event(
+                                                   TimedEvent(std::chrono::steady_clock::now() + 5s,
+                                                              std::bind(&TCPSocketHandler::on_connection_timeout, this),
+                                                              "connection_timeout"s + std::to_string(this->socket)));
+          return ;
+        }
+      log_info("Connection failed:" << strerror(errno));
+    }
+  log_error("All connection attempts failed.");
+  this->close();
+  this->on_connection_failed(strerror(errno));
+  return ;
+}
+
+void TCPSocketHandler::on_connection_timeout()
+{
+  this->close();
+  this->on_connection_failed("connection timed out");
+}
+
+void TCPSocketHandler::connect()
+{
+  this->connect(this->address, this->port, this->use_tls);
+}
+
+void TCPSocketHandler::on_recv()
+{
+#ifdef BOTAN_FOUND
+  if (this->use_tls)
+    this->tls_recv();
+  else
+#endif
+    this->plain_recv();
+}
+
+void TCPSocketHandler::plain_recv()
+{
+  static constexpr size_t buf_size = 4096;
+  char buf[buf_size];
+  void* recv_buf = this->get_receive_buffer(buf_size);
+
+  if (recv_buf == nullptr)
+    recv_buf = buf;
+
+  const ssize_t size = this->do_recv(recv_buf, buf_size);
+
+  if (size > 0)
+    {
+      if (buf == recv_buf)
+        {
+          // data needs to be placed in the in_buf string, because no buffer
+          // was provided to receive that data directly. The in_buf buffer
+          // will be handled in parse_in_buffer()
+          this->in_buf += std::string(buf, size);
+        }
+      this->parse_in_buffer(size);
+    }
+}
+
+ssize_t TCPSocketHandler::do_recv(void* recv_buf, const size_t buf_size)
+{
+  ssize_t size = ::recv(this->socket, recv_buf, buf_size, 0);
+  if (0 == size)
+    {
+      this->on_connection_close("");
+      this->close();
+    }
+  else if (-1 == size)
+    {
+      log_warning("Error while reading from socket: " << strerror(errno));
+      // Remember if we were connecting, or already connected when this
+      // happened, because close() sets this->connecting to false
+      const auto were_connecting = this->connecting;
+      this->close();
+      if (were_connecting)
+        this->on_connection_failed(strerror(errno));
+      else
+        this->on_connection_close(strerror(errno));
+    }
+  return size;
+}
+
+void TCPSocketHandler::on_send()
+{
+  struct iovec msg_iov[UIO_FASTIOV] = {};
+  struct msghdr msg{nullptr, 0,
+      msg_iov,
+      0, nullptr, 0, 0};
+  for (std::string& s: this->out_buf)
+    {
+      // unconsting the content of s is ok, sendmsg will never modify it
+      msg_iov[msg.msg_iovlen].iov_base = const_cast<char*>(s.data());
+      msg_iov[msg.msg_iovlen].iov_len = s.size();
+      if (++msg.msg_iovlen == UIO_FASTIOV)
+        break;
+    }
+  ssize_t res = ::sendmsg(this->socket, &msg, MSG_NOSIGNAL);
+  if (res < 0)
+    {
+      log_error("sendmsg failed: " << strerror(errno));
+      this->on_connection_close(strerror(errno));
+      this->close();
+    }
+  else
+    {
+      // remove all the strings that were successfully sent.
+      for (auto it = this->out_buf.begin();
+           it != this->out_buf.end();)
+        {
+          if (static_cast<size_t>(res) >= (*it).size())
+            {
+              res -= (*it).size();
+              it = this->out_buf.erase(it);
+            }
+          else
+            {
+              // If one string has partially been sent, we use substr to
+              // crop it
+              if (res > 0)
+                (*it) = (*it).substr(res, std::string::npos);
+              break;
+            }
+        }
+      if (this->out_buf.empty())
+        this->poller->stop_watching_send_events(this);
+    }
+}
+
+void TCPSocketHandler::close()
+{
+  TimedEventsManager::instance().cancel("connection_timeout"s +
+                                        std::to_string(this->socket));
+  if (this->connected || this->connecting)
+    this->poller->remove_socket_handler(this->get_socket());
+  if (this->socket != -1)
+    {
+      ::close(this->socket);
+      this->socket = -1;
+    }
+  this->connected = false;
+  this->connecting = false;
+#ifdef CARES_FOUND
+  this->resolving = false;
+  this->resolved = false;
+  this->resolved4 = false;
+  this->resolved6 = false;
+  this->free_cares_addrinfo();
+  this->cares_error.clear();
+#endif
+  this->in_buf.clear();
+  this->out_buf.clear();
+  this->port.clear();
+}
+
+void TCPSocketHandler::send_data(std::string&& data)
+{
+#ifdef BOTAN_FOUND
+  if (this->use_tls)
+    this->tls_send(std::move(data));
+  else
+#endif
+    this->raw_send(std::move(data));
+}
+
+void TCPSocketHandler::raw_send(std::string&& data)
+{
+  if (data.empty())
+    return ;
+  this->out_buf.emplace_back(std::move(data));
+  if (this->connected)
+    this->poller->watch_send_events(this);
+}
+
+void TCPSocketHandler::send_pending_data()
+{
+  if (this->connected && !this->out_buf.empty())
+    this->poller->watch_send_events(this);
+}
+
+bool TCPSocketHandler::is_connected() const
+{
+  return this->connected;
+}
+
+bool TCPSocketHandler::is_connecting() const
+{
+#ifdef CARES_FOUND
+  return this->connecting || this->resolving;
+#else
+  return this->connecting;
+#endif
+}
+
+void* TCPSocketHandler::get_receive_buffer(const size_t) const
+{
+  return nullptr;
+}
+
+#ifdef BOTAN_FOUND
+void TCPSocketHandler::start_tls()
+{
+  Botan::TLS::Server_Information server_info(this->address, "irc", std::stoul(this->port));
+  this->tls = std::make_unique<Botan::TLS::Client>(
+      std::bind(&TCPSocketHandler::tls_output_fn, this, ph::_1, ph::_2),
+      std::bind(&TCPSocketHandler::tls_data_cb, this, ph::_1, ph::_2),
+      std::bind(&TCPSocketHandler::tls_alert_cb, this, ph::_1, ph::_2, ph::_3),
+      std::bind(&TCPSocketHandler::tls_handshake_cb, this, ph::_1),
+      session_manager, credential_manager, policy,
+      rng, server_info, Botan::TLS::Protocol_Version::latest_tls_version());
+}
+
+void TCPSocketHandler::tls_recv()
+{
+  static constexpr size_t buf_size = 4096;
+  char recv_buf[buf_size];
+
+  const ssize_t size = this->do_recv(recv_buf, buf_size);
+  if (size > 0)
+    {
+      const bool was_active = this->tls->is_active();
+      this->tls->received_data(reinterpret_cast<const Botan::byte*>(recv_buf),
+                              static_cast<size_t>(size));
+      if (!was_active && this->tls->is_active())
+        this->on_tls_activated();
+    }
+}
+
+void TCPSocketHandler::tls_send(std::string&& data)
+{
+  if (this->tls->is_active())
+    {
+      const bool was_active = this->tls->is_active();
+      if (!this->pre_buf.empty())
+        {
+          this->tls->send(reinterpret_cast<const Botan::byte*>(this->pre_buf.data()),
+                         this->pre_buf.size());
+          this->pre_buf = "";
+        }
+      if (!data.empty())
+        this->tls->send(reinterpret_cast<const Botan::byte*>(data.data()),
+                       data.size());
+      if (!was_active && this->tls->is_active())
+        this->on_tls_activated();
+    }
+  else
+    this->pre_buf += data;
+}
+
+void TCPSocketHandler::tls_data_cb(const Botan::byte* data, size_t size)
+{
+  this->in_buf += std::string(reinterpret_cast<const char*>(data),
+                              size);
+  if (!this->in_buf.empty())
+    this->parse_in_buffer(size);
+}
+
+void TCPSocketHandler::tls_output_fn(const Botan::byte* data, size_t size)
+{
+  this->raw_send(std::string(reinterpret_cast<const char*>(data), size));
+}
+
+void TCPSocketHandler::tls_alert_cb(Botan::TLS::Alert alert, const Botan::byte*, size_t)
+{
+  log_debug("tls_alert: " << alert.type_string());
+}
+
+bool TCPSocketHandler::tls_handshake_cb(const Botan::TLS::Session& session)
+{
+  log_debug("Handshake with " << session.server_info().hostname() << " complete."
+            << " Version: " << session.version().to_string()
+            << " using " << session.ciphersuite().to_string());
+  if (!session.session_id().empty())
+    log_debug("Session ID " << Botan::hex_encode(session.session_id()));
+  if (!session.session_ticket().empty())
+    log_debug("Session ticket " << Botan::hex_encode(session.session_ticket()));
+  return true;
+}
+
+void TCPSocketHandler::on_tls_activated()
+{
+  this->send_data("");
+}
+
+void Permissive_Credentials_Manager::verify_certificate_chain(const std::string& type,
+                                                const std::string& purported_hostname,
+                                                const std::vector<Botan::X509_Certificate>&)
+{ // TODO: Offer the admin to disallow connection on untrusted
+  // certificates
+  log_debug("Checking remote certificate (" << type << ") for hostname " << purported_hostname);
+}
+
+#endif // BOTAN_FOUND
+
+#ifdef CARES_FOUND
+
+void TCPSocketHandler::on_hostname4_resolved(int status, struct hostent* hostent)
+{
+  this->resolved4 = true;
+  if (status == ARES_SUCCESS)
+    this->fill_ares_addrinfo4(hostent);
+  else
+    this->cares_error = ::ares_strerror(status);
+
+  if (this->resolved4 && this->resolved6)
+    {
+      this->resolved = true;
+      this->resolving = false;
+      this->connect();
+    }
+}
+
+void TCPSocketHandler::on_hostname6_resolved(int status, struct hostent* hostent)
+{
+  this->resolved6 = true;
+  if (status == ARES_SUCCESS)
+    this->fill_ares_addrinfo6(hostent);
+  else
+    this->cares_error = ::ares_strerror(status);
+
+  if (this->resolved4 && this->resolved6)
+    {
+      this->resolved = true;
+      this->resolving = false;
+      this->connect();
+    }
+}
+
+void TCPSocketHandler::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* addr = new struct sockaddr_in;
+      addr->sin_family = hostent->h_addrtype;
+      addr->sin_port = htons(strtoul(this->port.data(), nullptr, 10));
+      addr->sin_addr.s_addr = (*address)->s_addr;
+
+      current->ai_addr = reinterpret_cast<struct sockaddr*>(addr);
+      current->ai_next = nullptr;
+      current->ai_canonname = nullptr;
+
+      current->ai_next = prev;
+      this->cares_addrinfo = current;
+      prev = current;
+      ++address;
+    }
+}
+
+void TCPSocketHandler::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* addr = new struct sockaddr_in6;
+      addr->sin6_family = hostent->h_addrtype;
+      addr->sin6_port = htons(strtoul(this->port.data(), nullptr, 10));
+      ::memcpy(addr->sin6_addr.s6_addr, (*address)->s6_addr, 16);
+      addr->sin6_flowinfo = 0;
+      addr->sin6_scope_id = 0;
+
+      current->ai_addr = reinterpret_cast<struct sockaddr*>(addr);
+      current->ai_next = nullptr;
+      current->ai_canonname = nullptr;
+
+      current->ai_next = prev;
+      this->cares_addrinfo = current;
+      prev = current;
+      ++address;
+    }
+}
+
+void TCPSocketHandler::free_cares_addrinfo()
+{
+  while (this->cares_addrinfo)
+    {
+      delete this->cares_addrinfo->ai_addr;
+      auto next = this->cares_addrinfo->ai_next;
+      delete this->cares_addrinfo;
+      this->cares_addrinfo = next;
+    }
+}
+
+#endif  // CARES_FOUND
diff --git a/louloulibs/network/tcp_socket_handler.hpp b/louloulibs/network/tcp_socket_handler.hpp
new file mode 100644
index 0000000..2b5cd49
--- /dev/null
+++ b/louloulibs/network/tcp_socket_handler.hpp
@@ -0,0 +1,293 @@
+#ifndef SOCKET_HANDLER_INCLUDED
+# define SOCKET_HANDLER_INCLUDED
+
+#include <network/socket_handler.hpp>
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netdb.h>
+
+#include <memory>
+#include <string>
+#include <list>
+
+#include "louloulibs.h"
+
+#ifdef CARES_FOUND
+# include <ares.h>
+#endif
+
+#ifdef BOTAN_FOUND
+# include <botan/botan.h>
+# include <botan/tls_client.h>
+
+/**
+ * A very simple credential manager that accepts any certificate.
+ */
+class Permissive_Credentials_Manager: public Botan::Credentials_Manager
+{
+public:
+  void verify_certificate_chain(const std::string& type,
+                                const std::string& purported_hostname,
+                                const std::vector<Botan::X509_Certificate>&);
+};
+#endif // BOTAN_FOUND
+
+/**
+ * An interface, with a series of callbacks that should be implemented in
+ * subclasses that deal with a socket. These callbacks are called on various events
+ * (read/write/timeout, etc) when they are notified to a poller
+ * (select/poll/epoll etc)
+ */
+class TCPSocketHandler: public SocketHandler
+{
+protected:
+  ~TCPSocketHandler();
+
+public:
+  explicit TCPSocketHandler(std::shared_ptr<Poller> poller);
+  /**
+   * Connect to the remote server, and call on_connected() if this
+   * succeeds. If tls is true, we set use_tls to true and will also call
+   * start_tls() when the connection succeeds.
+   */
+  void connect(const std::string& address, const std::string& port, const bool tls);
+  void connect() override final;
+  /**
+   * Reads raw data from the socket. And pass it to parse_in_buffer()
+   * If we are using TLS on this connection, we call tls_recv()
+   */
+  void on_recv() override final;
+  /**
+   * Write as much data from out_buf as possible, in the socket.
+   */
+  void on_send() override final;
+  /**
+   * Add the given data to out_buf and tell our poller that we want to be
+   * notified when a send event is ready.
+   *
+   * This can be overriden if we want to modify the data before sending
+   * it. For example if we want to encrypt it.
+   */
+  void send_data(std::string&& data);
+  /**
+   * Watch the socket for send events, if our out buffer is not empty.
+   */
+  void send_pending_data();
+  /**
+   * Close the connection, remove us from the poller
+   */
+  void close();
+  /**
+   * Called by a TimedEvent, when the connection did not succeed or fail
+   * after a given time.
+   */
+  void on_connection_timeout();
+  /**
+   * Called when the connection is successful.
+   */
+  virtual void on_connected() = 0;
+  /**
+   * Called when the connection fails. Not when it is closed later, just at
+   * the connect() call.
+   */
+  virtual void on_connection_failed(const std::string& reason) = 0;
+  /**
+   * Called when we detect a disconnection from the remote host.
+   */
+  virtual void on_connection_close(const std::string& error) = 0;
+  /**
+   * Handle/consume (some of) the data received so far.  The data to handle
+   * may be in the in_buf buffer, or somewhere else, depending on what
+   * get_receive_buffer() returned.  If some data is used from in_buf, it
+   * should be truncated, only the unused data should be left untouched.
+   *
+   * The size argument is the size of the last chunk of data that was added to the buffer.
+   */
+  virtual void parse_in_buffer(const size_t size) = 0;
+  bool is_connected() const override final;
+  bool is_connecting() const;
+
+#ifdef CARES_FOUND
+  void on_hostname4_resolved(int status, struct hostent* hostent);
+  void on_hostname6_resolved(int status, struct hostent* hostent);
+
+  void free_cares_addrinfo();
+
+  void fill_ares_addrinfo4(const struct hostent* hostent);
+  void fill_ares_addrinfo6(const struct hostent* hostent);
+#endif
+
+private:
+  /**
+   * Initialize the socket with the parameters contained in the given
+   * addrinfo structure.
+   */
+  void init_socket(const struct addrinfo* rp);
+  /**
+   * Reads from the socket into the provided buffer.  If an error occurs
+   * (read returns <= 0), the handling of the error is done here (close the
+   * connection, log a message, etc).
+   *
+   * Returns the value returned by ::recv(), so the buffer should not be
+   * used if it’s not positive.
+   */
+  ssize_t do_recv(void* recv_buf, const size_t buf_size);
+  /**
+   * Reads data from the socket and calls parse_in_buffer with it.
+   */
+  void plain_recv();
+  /**
+   * Mark the given data as ready to be sent, as-is, on the socket, as soon
+   * as we can.
+   */
+  void raw_send(std::string&& data);
+
+#ifdef BOTAN_FOUND
+  /**
+   * Create the TLS::Client object, with all the callbacks etc. This must be
+   * called only when we know we are able to send TLS-encrypted data over
+   * the socket.
+   */
+  void start_tls();
+  /**
+   * An additional step to pass the data into our tls object to decrypt it
+   * before passing it to parse_in_buffer.
+   */
+  void tls_recv();
+  /**
+   * Pass the data to the tls object in order to encrypt it. The tls object
+   * will then call raw_send as a callback whenever data as been encrypted
+   * and can be sent on the socket.
+   */
+  void tls_send(std::string&& data);
+  /**
+   * Called by the tls object that some data has been decrypt. We call
+   * parse_in_buffer() to handle that unencrypted data.
+   */
+  void tls_data_cb(const Botan::byte* data, size_t size);
+  /**
+   * Called by the tls object to indicate that some data has been encrypted
+   * and is now ready to be sent on the socket as is.
+   */
+  void tls_output_fn(const Botan::byte* data, size_t size);
+  /**
+   * Called by the tls object to indicate that a TLS alert has been
+   * received. We don’t use it, we just log some message, at the moment.
+   */
+  void tls_alert_cb(Botan::TLS::Alert alert, const Botan::byte*, size_t);
+  /**
+   * Called by the tls object at the end of the TLS handshake. We don't do
+   * anything here appart from logging the TLS session information.
+   */
+  bool tls_handshake_cb(const Botan::TLS::Session& session);
+  /**
+   * Called whenever the tls session goes from inactive to active. This
+   * means that the handshake has just been successfully done, and we can
+   * now proceed to send any available data into our tls object.
+   */
+  void on_tls_activated();
+#endif // BOTAN_FOUND
+  /**
+   * Where data is added, when we want to send something to the client.
+   */
+  std::list<std::string> out_buf;
+  /**
+   * Keep the details of the addrinfo that triggered a EINPROGRESS error when
+   * connect()ing to it, to reuse it directly when connect() is called
+   * again.
+   */
+  struct addrinfo addrinfo;
+  struct sockaddr_in6 ai_addr;
+  socklen_t ai_addrlen;
+
+protected:
+  /**
+   * Where data read from the socket is added until we can extract a full
+   * and meaningful “message” from it.
+   *
+   * TODO: something more efficient than a string.
+   */
+  std::string in_buf;
+  /**
+   * Whether we are using TLS on this connection or not.
+   */
+  bool use_tls;
+  /**
+   * Provide a buffer in which data can be directly received. This can be
+   * used to avoid copying data into in_buf before using it. If no buffer
+   * needs to be provided, nullptr is returned (the default implementation
+   * does that), in that case our internal in_buf will be used to save the
+   * data until it can be used by parse_in_buffer().
+   */
+  virtual void* get_receive_buffer(const size_t size) const;
+  /**
+   * Hostname we are connected/connecting to
+   */
+  std::string address;
+  /**
+   * Port we are connected/connecting to
+   */
+  std::string port;
+
+  bool connected;
+  bool connecting;
+
+#ifdef CARES_FOUND
+  bool resolving;
+  /**
+   * Whether or not the DNS resolution was successfully done
+   */
+  bool resolved;
+  bool resolved4;
+  bool resolved6;
+  /**
+   * When using c-ares to resolve the host asynchronously, we need the
+   * c-ares callback 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 next call of connect() will then try all these values
+   * (exactly like we do with the result of getaddrinfo) and save the one
+   * that worked (or returned EINPROGRESS) in the other struct addrinfo (see
+   * the members addrinfo, ai_addrlen, and ai_addr).
+   */
+  struct addrinfo* cares_addrinfo;
+  std::string cares_error;
+#endif  // CARES_FOUND
+
+private:
+  TCPSocketHandler(const TCPSocketHandler&) = delete;
+  TCPSocketHandler(TCPSocketHandler&&) = delete;
+  TCPSocketHandler& operator=(const TCPSocketHandler&) = delete;
+  TCPSocketHandler& operator=(TCPSocketHandler&&) = delete;
+
+#ifdef BOTAN_FOUND
+  /**
+   * Botan stuff to manipulate a TLS session.
+   */
+  static Botan::AutoSeeded_RNG rng;
+  static Permissive_Credentials_Manager credential_manager;
+  static Botan::TLS::Policy policy;
+  static Botan::TLS::Session_Manager_In_Memory session_manager;
+  /**
+   * We use a unique_ptr because we may not want to create the object at
+   * all. The Botan::TLS::Client object generates a handshake message as
+   * soon and calls the output_fn callback with it as soon as it is
+   * created. Therefore, we do not want to create it if do not intend to do
+   * send any TLS-encrypted message. We create the object only when needed
+   * (for example after we have negociated a TLS session using a STARTTLS
+   * message, or stuf like that).
+   *
+   * See start_tls for the method where this object is created.
+   */
+  std::unique_ptr<Botan::TLS::Client> tls;
+  /**
+   * An additional buffer to keep data that the user wants to send, but
+   * cannot because the handshake is not done.
+   */
+  std::string pre_buf;
+#endif // BOTAN_FOUND
+};
+
+#endif // SOCKET_HANDLER_INCLUDED