First step of the connection skeleton

Basic connect, socket creating, polling, recving, etc.

3 files changed, 230 insertions, 0 deletions

diff --git a/src/network/poller.cpp b/src/network/poller.cpp
new file mode 100644
index 0000000..c7d9eb2
--- /dev/null
+++ b/src/network/poller.cpp
@@ -0,0 +1,96 @@
+#include <network/poller.hpp>
+
+#include <assert.h>
+#include <cstring>
+#include <iostream>
+
+
+Poller::Poller()
+{
+  std::cout << "Poller()" << std::endl;
+#if POLLER == POLL
+  memset(this->fds, 0, sizeof(this->fds));
+  this->nfds = 0;
+#endif
+}
+
+Poller::~Poller()
+{
+  std::cout << "~Poller()" << std::endl;
+}
+
+void Poller::add_socket_handler(std::shared_ptr<SocketHandler> socket_handler)
+{
+  // Raise an error if that socket is already in the list
+  const auto it = this->socket_handlers.find(socket_handler->get_socket());
+  if (it != this->socket_handlers.end())
+    throw std::runtime_error("Trying to insert SocketHandler already managed");
+
+  this->socket_handlers.emplace(socket_handler->get_socket(), socket_handler);
+  socket_handler->set_poller(this);
+
+  // 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
+}
+
+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);
+  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--;
+        }
+    }
+}
+
+void Poller::poll()
+{
+#if POLLER == POLL
+  std::cout << "Polling:" << std::endl;
+  for (size_t i = 0; i < this->nfds; ++i)
+    std::cout << "pollfd[" << i << "]: (" << this->fds[i].fd << ")" << std::endl;
+  int res = ::poll(this->fds, this->nfds, -1);
+  if (res < 0)
+    {
+      perror("poll");
+      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>(res) <= this->nfds);
+  for (size_t i = 0; i <= this->nfds && res != 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();
+          res--;
+        }
+      else if (this->fds[i].revents & POLLOUT)
+        {
+          auto socket_handler = this->socket_handlers.at(this->fds[i].fd);
+          socket_handler->on_send();
+          res--;
+        }
+    }
+#endif
+}
+
diff --git a/src/network/poller.hpp b/src/network/poller.hpp
new file mode 100644
index 0000000..46a184e
--- /dev/null
+++ b/src/network/poller.hpp
@@ -0,0 +1,72 @@
+#ifndef POLLER_INCLUDED
+# define POLLER_INCLUDED
+
+#include <network/socket_handler.hpp>
+
+#include <unordered_map>
+#include <memory>
+
+#define POLL 1
+#define EPOLL 2
+#define KQUEUE 3
+
+#define POLLER POLL
+
+#if POLLER == POLL
+ #include <poll.h>
+ // TODO, dynamic size, without artificial limit
+ #define MAX_POLL_FD_NUMBER 4096
+#endif
+
+/**
+ * We pass some SocketHandlers to this the Poller, which uses
+ * poll/epoll/kqueue/select etc to wait for events on these SocketHandlers,
+ * and call the callbacks when event occurs.
+ *
+ * TODO: support for all these pollers:
+ * - poll(2) (mandatory)
+ * - epoll(7)
+ * - 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(std::shared_ptr<SocketHandler> socket_handler);
+  /**
+   * Remove (and stop managing) a SocketHandler, designed by the given socket_t.
+   */
+  void remove_socket_handler(const socket_t socket);
+  /**
+   * Wait for all watched events, and call the SocketHandlers' callbacks
+   * when one is ready.
+   */
+  void poll();
+
+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, std::shared_ptr<SocketHandler>> socket_handlers;
+
+#if POLLER == POLL
+  struct pollfd fds[MAX_POLL_FD_NUMBER];
+  nfds_t nfds;
+#endif
+
+  Poller(const Poller&) = delete;
+  Poller(Poller&&) = delete;
+  Poller& operator=(const Poller&) = delete;
+  Poller& operator=(Poller&&) = delete;
+};
+
+#endif // POLLER_INCLUDED
diff --git a/src/network/socket_handler.hpp b/src/network/socket_handler.hpp
new file mode 100644
index 0000000..165f732
--- /dev/null
+++ b/src/network/socket_handler.hpp
@@ -0,0 +1,62 @@
+#ifndef SOCKET_HANDLER_INCLUDED
+# define SOCKET_HANDLER_INCLUDED
+
+typedef int socket_t;
+
+class Poller;
+
+/**
+ * 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 SocketHandler
+{
+public:
+  explicit SocketHandler():
+    poller(nullptr)
+  {}
+  /**
+   * Set the pointer to the given Poller, to communicate with it.
+   */
+  void set_poller(Poller* poller)
+  {
+    this->poller = poller;
+  };
+  /**
+   * Happens when the socket is ready to be received from.
+   */
+  virtual void on_recv() = 0;
+  /**
+   * Happens when the socket is ready to be written to.
+   */
+  virtual void on_send() = 0;
+  /**
+   * Returns the socket that should be handled by the poller.
+   */
+  virtual socket_t get_socket() const = 0;
+  /**
+   * Close the connection.
+   */
+  virtual void close() = 0;
+
+protected:
+  /**
+   * A pointer to the poller that manages us, because we need to communicate
+   * with it, sometimes (for example to tell it that he now needs to watch
+   * write events for us). Do not ever try to delete it.
+   *
+   * And a raw pointer because we are not owning it, it is owning us
+   * (actually it is sharing our ownership with a Bridge).
+   */
+  Poller* poller;
+
+private:
+  SocketHandler(const SocketHandler&) = delete;
+  SocketHandler(SocketHandler&&) = delete;
+  SocketHandler& operator=(const SocketHandler&) = delete;
+  SocketHandler& operator=(SocketHandler&&) = delete;
+};
+
+#endif // SOCKET_HANDLER_INCLUDED