Introducing UDP listener.

include/envoy/event/dispatcher.h

@@ -90,7 +90,7 @@ class Dispatcher {
    *               initially listen on.
    */
   virtual FileEventPtr createFileEvent(int fd, FileReadyCb cb, FileTriggerType trigger,
-                                       uint32_t events) PURE;
+                                       uint32_t events) const PURE;
 
   /**
    * @return Filesystem::WatcherPtr a filesystem watcher owned by the caller.
@@ -110,6 +110,14 @@ class Dispatcher {
                                               Network::ListenerCallbacks& cb, bool bind_to_port,
                                               bool hand_off_restored_destination_connections) PURE;
 
+  /**
+   * Create a logical udp listener on a specific port.
+   * @param socket supplies the socket to listen on.
+   * @param cb supplies the udp listener callbacks to invoke for listener events.
+   * @return Network::ListenerPtr a new listener that is owned by the caller.
+   */
+  virtual Network::ListenerPtr createUdpListener(Network::Socket& socket,
+                                                 Network::UdpListenerCallbacks& cb) PURE;
   /**
    * Allocate a timer. @see Timer for docs on how to use the timer.
    * @param cb supplies the callback to invoke when the timer fires.

include/envoy/network/listener.h

@@ -114,6 +114,59 @@ class ListenerCallbacks {
   virtual void onNewConnection(ConnectionPtr&& new_connection) PURE;
 };
 
+/**
+ * Utility struct that encapsulates the information from a udp socket's
+ * recvfrom/recvmmsg call.
+ *
+ * TODO(conqerAtapple): Maybe this belongs inside the UdpListenerCallbacks
+ * class.
+ */
+struct UdpData {
+  Address::InstanceConstSharedPtr local_address_;
+  Address::InstanceConstSharedPtr peer_address_; // TODO(conquerAtapple): Fix ownership semantics.
+  Buffer::InstancePtr buffer_;
+  // TODO(conquerAtapple):
+  // Add UdpReader here so that the callback handler can
+  // then use the reader to do multiple reads(recvmmsg) once the OS notifies it
+  // has data. We could also just return a `ReaderFactory` that returns either a
+  // `recvfrom` reader (with peer information) or a `read/recvmmsg` reader. This
+  // is still being flushed out (Jan, 2019).
+};
+
+/**
+ * Udp listener callbacks.
+ */
+class UdpListenerCallbacks {
+public:
+  enum class ErrorCode { SyscallError, UnknownError };
+
+  virtual ~UdpListenerCallbacks() = default;
+
+  /**
+   * Called whenever data is received by the underlying udp socket.
+   *
+   * @param data UdpData from the underlying socket.
+   */
+  virtual void onData(const UdpData& data) PURE;
+
+  /**
+   * Called when the underlying socket is ready for write.
+   *
+   * @param socket Underlying server socket for the listener.
+   *
+   * TODO(conqerAtapple): Maybe we need a UdpWriter here instead of Socket.
+   */
+  virtual void onWriteReady(const Socket& socket) PURE;
+
+  /**
+   * Called when there is an error event.
+   *
+   * @param error_code ErrorCode for the error event.
+   * @param error_number System error number.
+   */
+  virtual void onError(const ErrorCode& error_code, int error_number) PURE;
+};
+
 /**
  * An abstract socket listener. Free the listener to stop listening on the socket.
  */

source/common/event/dispatcher_impl.cc

@@ -19,6 +19,7 @@
 #include "common/network/connection_impl.h"
 #include "common/network/dns_impl.h"
 #include "common/network/listener_impl.h"
+#include "common/network/udp_listener_impl.h"
 
 #include "event2/event.h"
 
@@ -101,7 +102,7 @@ Network::DnsResolverSharedPtr DispatcherImpl::createDnsResolver(
 }
 
 FileEventPtr DispatcherImpl::createFileEvent(int fd, FileReadyCb cb, FileTriggerType trigger,
-                                             uint32_t events) {
+                                             uint32_t events) const {
   ASSERT(isThreadSafe());
   return FileEventPtr{new FileEventImpl(*this, fd, cb, trigger, events)};
 }
@@ -119,6 +120,12 @@ DispatcherImpl::createListener(Network::Socket& socket, Network::ListenerCallbac
                                                         hand_off_restored_destination_connections)};
 }
 
+Network::ListenerPtr DispatcherImpl::createUdpListener(Network::Socket& socket,
+                                                       Network::UdpListenerCallbacks& cb) {
+  ASSERT(isThreadSafe());
+  return Network::ListenerPtr{new Network::UdpListenerImpl(*this, socket, cb)};
+}
+
 TimerPtr DispatcherImpl::createTimer(TimerCb cb) {
   ASSERT(isThreadSafe());
   return scheduler_->createTimer(cb);

source/common/event/dispatcher_impl.h

@@ -30,7 +30,7 @@ class DispatcherImpl : Logger::Loggable<Logger::Id::main>, public Dispatcher {
   /**
    * @return event_base& the libevent base.
    */
-  event_base& base() { return *base_; }
+  event_base& base() const { return *base_; }
 
   // Event::Dispatcher
   TimeSystem& timeSystem() override { return time_system_; }
@@ -46,11 +46,13 @@ class DispatcherImpl : Logger::Loggable<Logger::Id::main>, public Dispatcher {
   Network::DnsResolverSharedPtr createDnsResolver(
       const std::vector<Network::Address::InstanceConstSharedPtr>& resolvers) override;
   FileEventPtr createFileEvent(int fd, FileReadyCb cb, FileTriggerType trigger,
-                               uint32_t events) override;
+                               uint32_t events) const override;
   Filesystem::WatcherPtr createFilesystemWatcher() override;
   Network::ListenerPtr createListener(Network::Socket& socket, Network::ListenerCallbacks& cb,
                                       bool bind_to_port,
                                       bool hand_off_restored_destination_connections) override;
+  Network::ListenerPtr createUdpListener(Network::Socket& socket,
+                                         Network::UdpListenerCallbacks& cb) override;
   TimerPtr createTimer(TimerCb cb) override;
   void deferredDelete(DeferredDeletablePtr&& to_delete) override;
   void exit() override;

source/common/event/file_event_impl.cc

@@ -10,7 +10,7 @@
 namespace Envoy {
 namespace Event {
 
-FileEventImpl::FileEventImpl(DispatcherImpl& dispatcher, int fd, FileReadyCb cb,
+FileEventImpl::FileEventImpl(const DispatcherImpl& dispatcher, int fd, FileReadyCb cb,
                              FileTriggerType trigger, uint32_t events)
     : cb_(cb), base_(&dispatcher.base()), fd_(fd), trigger_(trigger) {
   assignEvents(events);

source/common/event/file_event_impl.h

@@ -16,7 +16,7 @@ namespace Event {
  */
 class FileEventImpl : public FileEvent, ImplBase {
 public:
-  FileEventImpl(DispatcherImpl& dispatcher, int fd, FileReadyCb cb, FileTriggerType trigger,
+  FileEventImpl(const DispatcherImpl& dispatcher, int fd, FileReadyCb cb, FileTriggerType trigger,
                 uint32_t events);
 
   // Event::FileEvent

source/common/network/BUILD

@@ -139,9 +139,15 @@ envoy_cc_library(
 envoy_cc_library(
     name = "listener_lib",
     srcs = [
+        "base_listener_impl.cc",
         "listener_impl.cc",
+        "udp_listener_impl.cc",
+    ],
+    hdrs = [
+        "base_listener_impl.h",
+        "listener_impl.h",
+        "udp_listener_impl.h",
     ],
-    hdrs = ["listener_impl.h"],
     deps = [
         ":address_lib",
         ":io_socket_handle_lib",
@@ -151,6 +157,7 @@ envoy_cc_library(
         "//include/envoy/network:listener_interface",
         "//include/envoy/stats:stats_interface",
         "//include/envoy/stats:stats_macros",
+        "//source/common/buffer:buffer_lib",
         "//source/common/common:assert_lib",
         "//source/common/common:empty_string",
         "//source/common/common:linked_object",

source/common/network/base_listener_impl.cc

@@ -0,0 +1,35 @@
+#include "common/network/base_listener_impl.h"
+
+#include <sys/un.h>
+
+#include "envoy/common/exception.h"
+
+#include "common/common/assert.h"
+#include "common/common/empty_string.h"
+#include "common/common/fmt.h"
+#include "common/event/dispatcher_impl.h"
+#include "common/event/file_event_impl.h"
+#include "common/network/address_impl.h"
+
+#include "event2/listener.h"
+
+namespace Envoy {
+namespace Network {
+
+Address::InstanceConstSharedPtr BaseListenerImpl::getLocalAddress(int fd) {
+  return Address::addressFromFd(fd);
+}
+
+BaseListenerImpl::BaseListenerImpl(const Event::DispatcherImpl& dispatcher, Socket& socket)
+    : local_address_(nullptr), dispatcher_(dispatcher), socket_(socket) {
+  const auto ip = socket.localAddress()->ip();
+
+  // Only use the listen socket's local address for new connections if it is not the all hosts
+  // address (e.g., 0.0.0.0 for IPv4).
+  if (!(ip && ip->isAnyAddress())) {
+    local_address_ = socket.localAddress();
+  }
+}
+
+} // namespace Network
+} // namespace Envoy

source/common/network/base_listener_impl.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include "envoy/network/listener.h"
+
+#include "common/event/dispatcher_impl.h"
+#include "common/event/libevent.h"
+#include "common/network/listen_socket_impl.h"
+
+#include "event2/event.h"
+
+namespace Envoy {
+namespace Network {
+
+/**
+ * Base libevent implementation of Network::Listener.
+ */
+class BaseListenerImpl : public Listener {
+public:
+  BaseListenerImpl(const Event::DispatcherImpl& dispatcher, Socket& socket);
+
+protected:
+  virtual Address::InstanceConstSharedPtr getLocalAddress(int fd);
+
+  Address::InstanceConstSharedPtr local_address_;
+  const Event::DispatcherImpl& dispatcher_;
+  Socket& socket_;
+};
+
+} // namespace Network
+} // namespace Envoy

source/common/network/listener_impl.cc

@@ -17,10 +17,6 @@
 namespace Envoy {
 namespace Network {
 
-Address::InstanceConstSharedPtr ListenerImpl::getLocalAddress(int fd) {
-  return Address::addressFromFd(fd);
-}
-
 void ListenerImpl::listenCallback(evconnlistener*, evutil_socket_t fd, sockaddr* remote_addr,
                                   int remote_addr_len, void* arg) {
   ListenerImpl* listener = static_cast<ListenerImpl*>(arg);
@@ -51,35 +47,32 @@ void ListenerImpl::listenCallback(evconnlistener*, evutil_socket_t fd, sockaddr*
       listener->hand_off_restored_destination_connections_);
 }
 
-ListenerImpl::ListenerImpl(Event::DispatcherImpl& dispatcher, Socket& socket, ListenerCallbacks& cb,
-                           bool bind_to_port, bool hand_off_restored_destination_connections)
-    : local_address_(nullptr), cb_(cb),
-      hand_off_restored_destination_connections_(hand_off_restored_destination_connections),
-      listener_(nullptr) {
-  const auto ip = socket.localAddress()->ip();
+void ListenerImpl::setupServerSocket(const Event::DispatcherImpl& dispatcher, Socket& socket) {
+  listener_.reset(
+      evconnlistener_new(&dispatcher.base(), listenCallback, this, 0, -1, socket.ioHandle().fd()));
 
-  // Only use the listen socket's local address for new connections if it is not the all hosts
-  // address (e.g., 0.0.0.0 for IPv4).
-  if (!(ip && ip->isAnyAddress())) {
-    local_address_ = socket.localAddress();
+  if (!listener_) {
+    throw CreateListenerException(
+        fmt::format("cannot listen on socket: {}", socket.localAddress()->asString()));
   }
 
-  if (bind_to_port) {
-    listener_.reset(evconnlistener_new(&dispatcher.base(), listenCallback, this, 0, -1,
-                                       socket.ioHandle().fd()));
-
-    if (!listener_) {
-      throw CreateListenerException(
-          fmt::format("cannot listen on socket: {}", socket.localAddress()->asString()));
-    }
+  if (!Network::Socket::applyOptions(socket.options(), socket,
+                                     envoy::api::v2::core::SocketOption::STATE_LISTENING)) {
+    throw CreateListenerException(fmt::format("cannot set post-listen socket option on socket: {}",
+                                              socket.localAddress()->asString()));
+  }
 
-    if (!Network::Socket::applyOptions(socket.options(), socket,
-                                       envoy::api::v2::core::SocketOption::STATE_LISTENING)) {
-      throw CreateListenerException(fmt::format(
-          "cannot set post-listen socket option on socket: {}", socket.localAddress()->asString()));
-    }
+  evconnlistener_set_error_cb(listener_.get(), errorCallback);
+}
 
-    evconnlistener_set_error_cb(listener_.get(), errorCallback);
+ListenerImpl::ListenerImpl(const Event::DispatcherImpl& dispatcher, Socket& socket,
+                           ListenerCallbacks& cb, bool bind_to_port,
+                           bool hand_off_restored_destination_connections)
+    : BaseListenerImpl(dispatcher, socket), cb_(cb),
+      hand_off_restored_destination_connections_(hand_off_restored_destination_connections),
+      listener_(nullptr) {
+  if (bind_to_port) {
+    setupServerSocket(dispatcher, socket);
   }
 }
 

source/common/network/listener_impl.h

@@ -1,38 +1,32 @@
 #pragma once
 
-#include "envoy/network/listener.h"
-
-#include "common/event/dispatcher_impl.h"
-#include "common/event/libevent.h"
-#include "common/network/listen_socket_impl.h"
-
-#include "event2/event.h"
+#include "base_listener_impl.h"
 
 namespace Envoy {
 namespace Network {
 
 /**
- * libevent implementation of Network::Listener.
+ * libevent implementation of Network::Listener for TCP.
+ * TODO(conqerAtapple): Consider renaming the class to `TcpListenerImpl`.
  */
-class ListenerImpl : public Listener {
+class ListenerImpl : public BaseListenerImpl {
 public:
-  ListenerImpl(Event::DispatcherImpl& dispatcher, Socket& socket, ListenerCallbacks& cb,
+  ListenerImpl(const Event::DispatcherImpl& dispatcher, Socket& socket, ListenerCallbacks& cb,
                bool bind_to_port, bool hand_off_restored_destination_connections);
 
-  void disable();
-  void enable();
+  void disable() override;
+  void enable() override;
 
 protected:
-  virtual Address::InstanceConstSharedPtr getLocalAddress(int fd);
+  void setupServerSocket(const Event::DispatcherImpl& dispatcher, Socket& socket);
 
-  Address::InstanceConstSharedPtr local_address_;
   ListenerCallbacks& cb_;
   const bool hand_off_restored_destination_connections_;
 
 private:
-  static void errorCallback(evconnlistener* listener, void* context);
   static void listenCallback(evconnlistener*, evutil_socket_t fd, sockaddr* remote_addr,
                              int remote_addr_len, void* arg);
+  static void errorCallback(evconnlistener* listener, void* context);
 
   Event::Libevent::ListenerPtr listener_;
 };