Initial work on the M17 protocol.

M17Network.cpp

@@ -0,0 +1,133 @@
+/*
+ *   Copyright (C) 2009-2014,2016,2019,2020 by Jonathan Naylor G4KLX
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "M17Network.h"
+#include "M17Defines.h"
+#include "Defines.h"
+#include "Utils.h"
+#include "Log.h"
+
+#include <cstdio>
+#include <cassert>
+#include <cstring>
+
+const unsigned int BUFFER_LENGTH = 200U;
+
+CM17Network::CM17Network(unsigned int localPort, const std::string& gatewayAddress, unsigned int gatewayPort, bool debug) :
+m_socket(localPort),
+m_addr(),
+m_addrLen(0U),
+m_debug(debug),
+m_enabled(false),
+m_buffer(1000U, "M17 Network")
+{
+	if (CUDPSocket::lookup(gatewayAddress, gatewayPort, m_addr, m_addrLen) != 0)
+		m_addrLen = 0U;
+}
+
+CM17Network::~CM17Network()
+{
+}
+
+bool CM17Network::open()
+{
+	if (m_addrLen == 0U) {
+		LogError("Unable to resolve the address of the M17 Gateway");
+		return false;
+	}
+
+	LogMessage("Opening M17 network connection");
+
+	return m_socket.open(m_addr);
+}
+
+bool CM17Network::write(const unsigned char* data)
+{
+	assert(data != NULL);
+
+	unsigned char buffer[100U];
+
+	buffer[0U] = 'M';
+	buffer[1U] = '1';
+	buffer[2U] = '7';
+
+	if (m_debug)
+		CUtils::dump(1U, "M17 data transmitted", buffer, 36U);
+
+	return m_socket.write(buffer, 36U, m_addr, m_addrLen);
+}
+
+void CM17Network::clock(unsigned int ms)
+{
+	unsigned char buffer[BUFFER_LENGTH];
+
+	sockaddr_storage address;
+	unsigned int addrLen;
+	int length = m_socket.read(buffer, BUFFER_LENGTH, address, addrLen);
+	if (length <= 0)
+		return;
+
+	if (!CUDPSocket::match(m_addr, address)) {
+		LogMessage("M17, packet received from an invalid source");
+		return;
+	}
+
+	if (!m_enabled)
+		return;
+
+	if (m_debug)
+		CUtils::dump(1U, "M17 Network Data Received", buffer, length);
+
+	if (::memcmp(buffer + 0U, "M17", 3U) != 0)
+		return;
+
+	unsigned char c = length;
+	m_buffer.addData(&c, 1U);
+
+	m_buffer.addData(buffer, length);
+}
+
+bool CM17Network::read(unsigned char* data)
+{
+	assert(data != NULL);
+
+	if (m_buffer.isEmpty())
+		return false;
+
+	unsigned char c = 0U;
+	m_buffer.getData(&c, 1U);
+
+	m_buffer.getData(data, c);
+
+	return true;
+}
+
+void CM17Network::close()
+{
+	m_socket.close();
+
+	LogMessage("Closing M17 network connection");
+}
+
+void CM17Network::enable(bool enabled)
+{
+	if (!enabled && m_enabled)
+		m_buffer.clear();
+
+	m_enabled = enabled;
+}