zeroconf/avahi/Client: new class, replacing lots of code from ZeroconfAvahi.cxx

src/zeroconf/avahi/Client.cxx

@@ -0,0 +1,139 @@
+/*
+ * Copyright 2007-2021 CM4all GmbH
+ * All rights reserved.
+ *
+ * author: Max Kellermann <mk@cm4all.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "Client.hxx"
+#include "ConnectionListener.hxx"
+#include "ErrorHandler.hxx"
+#include "Error.hxx"
+
+#include <avahi-common/error.h>
+
+#include <cassert>
+
+namespace Avahi {
+
+Client::Client(EventLoop &event_loop, ErrorHandler &_error_handler) noexcept
+	:error_handler(_error_handler),
+	 reconnect_timer(event_loop, BIND_THIS_METHOD(OnReconnectTimer)),
+	 poll(event_loop)
+{
+	reconnect_timer.Schedule({});
+}
+
+Client::~Client() noexcept
+{
+	Close();
+}
+
+void
+Client::Close() noexcept
+{
+	if (client != nullptr) {
+		for (auto *l : listeners)
+			l->OnAvahiDisconnect();
+
+		avahi_client_free(client);
+		client = nullptr;
+	}
+
+	reconnect_timer.Cancel();
+}
+
+void
+Client::ClientCallback(AvahiClient *c, AvahiClientState state) noexcept
+{
+	int error;
+
+	switch (state) {
+	case AVAHI_CLIENT_S_RUNNING:
+		for (auto *l : listeners)
+			l->OnAvahiConnect(c);
+
+		break;
+
+	case AVAHI_CLIENT_FAILURE:
+		error = avahi_client_errno(c);
+		if (error == AVAHI_ERR_DISCONNECTED) {
+			Close();
+
+			reconnect_timer.Schedule(std::chrono::seconds(10));
+		} else {
+			if (!error_handler.OnAvahiError(std::make_exception_ptr(MakeError(error,
+											  "Avahi connection error"))))
+				return;
+
+			reconnect_timer.Schedule(std::chrono::minutes(1));
+		}
+
+		for (auto *l : listeners)
+			l->OnAvahiDisconnect();
+
+		break;
+
+	case AVAHI_CLIENT_S_COLLISION:
+	case AVAHI_CLIENT_S_REGISTERING:
+		for (auto *l : listeners)
+			l->OnAvahiChanged();
+
+		break;
+
+	case AVAHI_CLIENT_CONNECTING:
+		break;
+	}
+}
+
+void
+Client::ClientCallback(AvahiClient *c, AvahiClientState state,
+		       void *userdata) noexcept
+{
+	auto &client = *(Client *)userdata;
+	client.ClientCallback(c, state);
+}
+
+void
+Client::OnReconnectTimer() noexcept
+{
+	int error;
+	client = avahi_client_new(&poll, AVAHI_CLIENT_NO_FAIL,
+				  ClientCallback, this,
+				  &error);
+	if (client == nullptr) {
+		if (!error_handler.OnAvahiError(std::make_exception_ptr(MakeError(error,
+										  "Failed to create Avahi client"))))
+			return;
+
+		reconnect_timer.Schedule(std::chrono::minutes(1));
+		return;
+	}
+}
+
+} // namespace Avahi

src/zeroconf/avahi/Client.hxx

@@ -0,0 +1,93 @@
+/*
+ * Copyright 2007-2021 CM4all GmbH
+ * All rights reserved.
+ *
+ * author: Max Kellermann <mk@cm4all.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include "Poll.hxx"
+#include "event/CoarseTimerEvent.hxx"
+
+#include <avahi-client/client.h>
+
+#include <forward_list>
+
+class EventLoop;
+
+namespace Avahi {
+
+class ErrorHandler;
+class ConnectionListener;
+
+class Client final {
+	ErrorHandler &error_handler;
+
+	CoarseTimerEvent reconnect_timer;
+
+	Poll poll;
+
+	AvahiClient *client = nullptr;
+
+	std::forward_list<ConnectionListener *> listeners;
+
+public:
+	Client(EventLoop &event_loop, ErrorHandler &_error_handler) noexcept;
+	~Client() noexcept;
+
+	Client(const Client &) = delete;
+	Client &operator=(const Client &) = delete;
+
+	EventLoop &GetEventLoop() const noexcept {
+		return poll.GetEventLoop();
+	}
+
+	void Close() noexcept;
+
+	AvahiClient *GetClient() noexcept {
+		return client;
+	}
+
+	void AddListener(ConnectionListener &listener) noexcept {
+		listeners.push_front(&listener);
+	}
+
+	void RemoveListener(ConnectionListener &listener) noexcept {
+		listeners.remove(&listener);
+	}
+
+private:
+	void ClientCallback(AvahiClient *c, AvahiClientState state) noexcept;
+	static void ClientCallback(AvahiClient *c, AvahiClientState state,
+				   void *userdata) noexcept;
+
+	void OnReconnectTimer() noexcept;
+};
+
+} // namespace Avahi

src/zeroconf/avahi/ConnectionListener.hxx

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2007-2021 CM4all GmbH
+ * All rights reserved.
+ *
+ * author: Max Kellermann <mk@cm4all.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <avahi-client/client.h>
+
+namespace Avahi {
+
+class ConnectionListener {
+public:
+	/**
+	 * The connection to the Avahi daemon has been established.
+	 *
+	 * Note that this may be called again after a collision
+	 * (AVAHI_CLIENT_S_COLLISION) or a host name change
+	 * (AVAHI_CLIENT_S_REGISTERING).
+	 */
+	virtual void OnAvahiConnect(AvahiClient *client) noexcept = 0;
+	virtual void OnAvahiDisconnect() noexcept = 0;
+
+	/**
+	 * Something about the Avahi connection has changed, e.g. a
+	 * collision (AVAHI_CLIENT_S_COLLISION) or a host name change
+	 * (AVAHI_CLIENT_S_REGISTERING).  Services shall be
+	 * unpublished now, and will be re-published in the following
+	 * OnAvahiConnect() call.
+	 */
+	virtual void OnAvahiChanged() noexcept {}
+};
+
+} // namespace Avahi

src/zeroconf/avahi/Error.cxx

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2007-2021 CM4all GmbH
+ * All rights reserved.
+ *
+ * author: Max Kellermann <mk@cm4all.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "Error.hxx"
+
+#include <avahi-client/client.h>
+#include <avahi-common/error.h>
+
+#include <system_error>
+
+namespace Avahi {
+
+ErrorCategory error_category;
+
+std::string
+ErrorCategory::message(int condition) const
+{
+	return avahi_strerror(condition);
+}
+
+std::system_error
+MakeError(AvahiClient &client, const char *msg) noexcept
+{
+	return MakeError(avahi_client_errno(&client), msg);
+}
+
+} // namespace Avahi

src/zeroconf/avahi/Error.hxx

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2007-2021 CM4all GmbH
+ * All rights reserved.
+ *
+ * author: Max Kellermann <mk@cm4all.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <system_error>
+
+struct AvahiClient;
+
+namespace Avahi {
+
+class ErrorCategory final : public std::error_category {
+public:
+	const char *name() const noexcept override {
+		return "avahi-client";
+	}
+
+	std::string message(int condition) const override;
+};
+
+extern ErrorCategory error_category;
+
+inline std::system_error
+MakeError(int error, const char *msg) noexcept
+{
+	return std::system_error(error, error_category, msg);
+}
+
+std::system_error
+MakeError(AvahiClient &client, const char *msg) noexcept;
+
+} // namespace Avahi

src/zeroconf/avahi/ErrorHandler.hxx

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2007-2021 CM4all GmbH
+ * All rights reserved.
+ *
+ * author: Max Kellermann <mk@cm4all.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <exception>
+
+struct AvahiClient;
+
+namespace Avahi {
+
+class ErrorHandler {
+public:
+	/**
+	 * @return true to keep retrying, false if the failed object
+	 * has been disposed
+	 */
+	virtual bool OnAvahiError(std::exception_ptr e) noexcept = 0;
+};
+
+} // namespace Avahi

src/zeroconf/avahi/meson.build

@@ -6,6 +6,8 @@ endif
 
 avahi = static_library(
   'avahi',
+  'Client.cxx',
+  'Error.cxx',
   'Poll.cxx',
   include_directories: inc,
   dependencies: [