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urfd/reflector/M17Protocol.cpp

424 lines
12 KiB

// Copyright © 2015 Jean-Luc Deltombe (LX3JL). All rights reserved.
// urfd -- The universal reflector
// Copyright © 2021 Thomas A. Early N7TAE
//
// 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 3 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, see <https://www.gnu.org/licenses/>.
#include "Main.h"
#include <string.h>
#include "M17Client.h"
#include "M17Protocol.h"
#include "M17Packet.h"
#include "Reflector.h"
#include "GateKeeper.h"
////////////////////////////////////////////////////////////////////////////////////////
// operation
bool CM17Protocol::Initialize(const char *type, const EProtocol ptype, const uint16_t port, const bool has_ipv4, const bool has_ipv6)
{
// base class
if (! CProtocol::Initialize(type, ptype, port, has_ipv4, has_ipv6))
return false;
// update time
m_LastKeepaliveTime.start();
// done
return true;
}
////////////////////////////////////////////////////////////////////////////////////////
// task
void CM17Protocol::Task(void)
{
CBuffer Buffer;
CIp Ip;
CCallsign Callsign;
char ToLinkModule;
std::unique_ptr<CDvHeaderPacket> Header;
std::unique_ptr<CDvFramePacket> Frame;
// handle incoming packets
#if DSTAR_IPV6==true
#if DSTAR_IPV4==true
if ( ReceiveDS(Buffer, Ip, 20) )
#else
if ( Receive6(Buffer, Ip, 20) )
#endif
#else
if ( Receive4(Buffer, Ip, 20) )
#endif
{
// crack the packet
if ( IsValidDvPacket(Buffer, Header, Frame) )
{
// callsign muted?
if ( g_GateKeeper.MayTransmit(Header->GetMyCallsign(), Ip, EProtocol::m17, Header->GetRpt2Module()) )
{
OnDvHeaderPacketIn(Header, Ip);
// xrf needs a voice frame every 20 ms and an M17 frame is 40 ms, so we need a duplicate
auto secondFrame = std::unique_ptr<CDvFramePacket>(new CDvFramePacket(*Frame.get()));
// This is a "first" packet, so clear the last packet status, since the real last packet it the secondFrame
if (Frame->IsLastPacket())
Frame->SetLastPacket(false);
// push the "first" packet
OnDvFramePacketIn(Frame, &Ip);
// push the "second" packet
OnDvFramePacketIn(secondFrame, &Ip); // push two packet because we need a packet every 20 ms
}
}
else if ( IsValidConnectPacket(Buffer, Callsign, ToLinkModule) )
{
std::cout << "M17 connect packet for module " << ToLinkModule << " from " << Callsign << " at " << Ip << std::endl;
// callsign authorized?
if ( g_GateKeeper.MayLink(Callsign, Ip, EProtocol::m17) && g_Reflector.IsValidModule(ToLinkModule) )
{
// valid module ?
if ( g_Reflector.IsValidModule(ToLinkModule) )
{
// acknowledge the request
Send("ACKN", Ip);
// create the client and append
g_Reflector.GetClients()->AddClient(std::make_shared<CM17Client>(Callsign, Ip, ToLinkModule));
g_Reflector.ReleaseClients();
}
else
{
std::cout << "M17 node " << Callsign << " connect attempt on non-existing module" << std::endl;
// deny the request
Send("NACK", Ip);
}
}
else
{
// deny the request
Send("NACK", Ip);
}
}
else if ( IsValidDisconnectPacket(Buffer, Callsign) )
{
std::cout << "M17 disconnect packet from " << Callsign << " at " << Ip << std::endl;
// find client
CClients *clients = g_Reflector.GetClients();
std::shared_ptr<CClient>client = clients->FindClient(Ip, EProtocol::m17);
if ( client != nullptr )
{
// remove it
clients->RemoveClient(client);
// and acknowledge the disconnect
Send("DISC", Ip);
}
g_Reflector.ReleaseClients();
}
else if ( IsValidKeepAlivePacket(Buffer, Callsign) )
{
// find all clients with that callsign & ip and keep them alive
CClients *clients = g_Reflector.GetClients();
auto it = clients->begin();
std::shared_ptr<CClient>client = nullptr;
while ( (client = clients->FindNextClient(Callsign, Ip, EProtocol::m17, it)) != nullptr )
{
client->Alive();
}
g_Reflector.ReleaseClients();
}
else
{
// invalid packet
std::string title("Unknown M17 packet from ");
title += Ip.GetAddress();
Buffer.Dump(title);
}
}
// handle end of streaming timeout
CheckStreamsTimeout();
// handle queue from reflector
HandleQueue();
// keep client alive
if ( m_LastKeepaliveTime.time() > M17_KEEPALIVE_PERIOD )
{
//
HandleKeepalives();
// update time
m_LastKeepaliveTime.start();
}
}
////////////////////////////////////////////////////////////////////////////////////////
// streams helpers
void CM17Protocol::OnDvHeaderPacketIn(std::unique_ptr<CDvHeaderPacket> &Header, const CIp &Ip)
{
// find the stream
auto stream = GetStream(Header->GetStreamId(), &Ip);
if ( stream )
{
// stream already open
// skip packet, but tickle the stream
stream->Tickle();
}
else
{
// no stream open yet, open a new one
CCallsign my(Header->GetMyCallsign());
CCallsign rpt1(Header->GetRpt1Callsign());
CCallsign rpt2(Header->GetRpt2Callsign());
// find this client
std::shared_ptr<CClient>client = g_Reflector.GetClients()->FindClient(Ip, EProtocol::m17);
if ( client )
{
// get client callsign
rpt1 = client->GetCallsign();
// and try to open the stream
if ( (stream = g_Reflector.OpenStream(Header, client)) != nullptr )
{
// keep the handle
m_Streams[stream->GetStreamId()] = stream;
}
}
// release
g_Reflector.ReleaseClients();
// update last heard
g_Reflector.GetUsers()->Hearing(my, rpt1, rpt2);
g_Reflector.ReleaseUsers();
}
}
////////////////////////////////////////////////////////////////////////////////////////
// queue helper
void CM17Protocol::HandleQueue(void)
{
m_Queue.Lock();
while ( !m_Queue.empty() )
{
// get the packet
auto packet = m_Queue.pop();
// get our sender's id
const auto module = packet->GetPacketModule();
// check if it's header and update cache
if ( packet->IsDvHeader() )
{
// this relies on queue feeder setting valid module id
// m_StreamsCache[module] will be created if it doesn't exist
m_StreamsCache[module].m_dvHeader = CDvHeaderPacket((const CDvHeaderPacket &)*packet.get());
m_StreamsCache[module].m_iSeqCounter = 0;
}
else if (packet->IsSecond() || packet->IsLastPacket())
{
// encode it
SM17Frame frame;
memcpy(frame.magic, "M17 ", 4);
if ( packet->IsLastPacket() )
{
EncodeLastM17Packet(frame, m_StreamsCache[module].m_dvHeader, (CDvFramePacket &)*packet.get(), m_StreamsCache[module].m_iSeqCounter++);
}
else if ( packet->IsDvFrame() )
{
EncodeM17Packet(frame, m_StreamsCache[module].m_dvHeader, (CDvFramePacket &)*packet.get(), m_StreamsCache[module].m_iSeqCounter++);
#ifdef DEBUG
Dump("Last M17 Packet:", frame.magic, sizeof(SM17Frame));
#endif
}
// push it to all our clients linked to the module and who are not streaming in
CClients *clients = g_Reflector.GetClients();
auto it = clients->begin();
std::shared_ptr<CClient>client = nullptr;
while ( (client = clients->FindNextClient(EProtocol::m17, it)) != nullptr )
{
// is this client busy ?
if ( !client->IsAMaster() && (client->GetReflectorModule() == module) )
{
// no, send the packet
Send(frame, client->GetIp());
}
}
g_Reflector.ReleaseClients();
}
}
m_Queue.Unlock();
}
////////////////////////////////////////////////////////////////////////////////////////
// keepalive helpers
void CM17Protocol::HandleKeepalives(void)
{
// M17 protocol sends and monitors keepalives packets
// event if the client is currently streaming
// so, send keepalives to all
CBuffer keepalive;
EncodeKeepAlivePacket(keepalive);
// iterate on clients
CClients *clients = g_Reflector.GetClients();
auto it = clients->begin();
std::shared_ptr<CClient>client = nullptr;
while ( (client = clients->FindNextClient(EProtocol::m17, it)) != nullptr )
{
// send keepalive
Send(keepalive, client->GetIp());
// is this client busy ?
if ( client->IsAMaster() )
{
// yes, just tickle it
client->Alive();
}
// check it's still with us
else if ( !client->IsAlive() )
{
// no, disconnect
Send("DISC", client->GetIp());
// remove it
std::cout << "M17 client " << client->GetCallsign() << " keepalive timeout" << std::endl;
clients->RemoveClient(client);
}
}
g_Reflector.ReleaseClients();
}
////////////////////////////////////////////////////////////////////////////////////////
// packet decoding helpers
bool CM17Protocol::IsValidConnectPacket(const CBuffer &Buffer, CCallsign &callsign, char &mod)
{
uint8_t tag[] = { 'C', 'O', 'N', 'N' };
bool valid = false;
if (11 == Buffer.size() && 0 == Buffer.Compare(tag, 4))
{
callsign.CodeIn(Buffer.data() + 4);
mod = Buffer.data()[10];
valid = (callsign.IsValid() && IsLetter(mod));
}
return valid;
}
bool CM17Protocol::IsValidDisconnectPacket(const CBuffer &Buffer, CCallsign &callsign)
{
uint8_t tag[] = { 'D', 'I', 'S', 'C' };
bool valid = false;
if ((Buffer.size() == 10) && (0 == Buffer.Compare(tag, 4)))
{
callsign.CodeIn(Buffer.data() + 4);
valid = callsign.IsValid();
}
return valid;
}
bool CM17Protocol::IsValidKeepAlivePacket(const CBuffer &Buffer, CCallsign &callsign)
{
uint8_t tag[] = { 'P', 'O', 'N', 'G' };
bool valid = false;
if ( (Buffer.size() == 10) || (0 == Buffer.Compare(tag, 4)) )
{
callsign.CodeIn(Buffer.data() + 4);
valid = callsign.IsValid();
}
return valid;
}
bool CM17Protocol::IsValidDvPacket(const CBuffer &Buffer, std::unique_ptr<CDvHeaderPacket> &header, std::unique_ptr<CDvFramePacket> &frame)
{
uint8_t tag[] = { 'M', '1', '7', ' ' };
if ( (Buffer.size() == sizeof(SM17Frame)) && (0 == Buffer.Compare(tag, sizeof(tag))) && (0x4U == (0x1CU & Buffer[19])) )
// Buffer[19] is the low-order byte of the uint16_t frametype.
// the 0x1CU mask (00011100 binary) just lets us see:
// 1. the encryptions bytes (mask 0x18U) which must be zero, and
// 2. the msb of the 2-bit payload type (mask 0x4U) which must be set. This bit set means it's voice or voice+data.
// An masked result of 0x4U means the payload contains Codec2 voice data and there is no encryption.
{
// Make the M17 header
CM17Packet m17(Buffer.data());
// get the header
header = std::unique_ptr<CDvHeaderPacket>(new CDvHeaderPacket(m17));
// get the frame
frame = std::unique_ptr<CDvFramePacket>(new CDvFramePacket(m17));
// check validity of packets
if ( header && header->IsValid() && frame && frame->IsValid() )
return true;
}
return false;
}
////////////////////////////////////////////////////////////////////////////////////////
// packet encoding helpers
void CM17Protocol::EncodeKeepAlivePacket(CBuffer &Buffer)
{
Buffer.resize(10);
memcpy(Buffer.data(), "PING", 4);
g_Reflector.GetCallsign().CodeOut(Buffer.data() + 4);
}
void CM17Protocol::EncodeM17Packet(SM17Frame &frame, const CDvHeaderPacket &Header, const CDvFramePacket &DvFrame, uint32_t iSeq) const
{
ECodecType codec_in = Header.GetCodecIn(); // We'll need this
// do the lich structure first
// first, the dest and src callsigns
Header.GetRpt2Callsign().CodeOut(frame.lich.addr_dst);
CCallsign from = g_Reflector.GetCallsign();
from.SetCSModule(Header.GetPacketModule());
from.CodeOut(frame.lich.addr_src);
// then the frame type, if the incoming frame is NOT an M17 1600, then it will be Voice only
frame.lich.frametype = htons((ECodecType::c2_1600==codec_in) ? 0x7U : 0x5U);
memcpy(frame.lich.nonce, DvFrame.GetNonce(), 14);
// now the main part of the packet
memcpy(frame.magic, "M17 ", 4);
// the frame number comes from the stream sequence counter
frame.framenumber = htons(iSeq % 0x8000U);
memcpy(frame.payload, DvFrame.GetCodecData(codec_in), 16);
frame.streamid = Header.GetStreamId(); // no host<--->network byte swapping since we never do any math on this value
// finally, calcualte the m17 CRC value and load it
frame.crc = htons(m17crc.CalcCRC(frame.magic, sizeof(SM17Frame)-2));
}
void CM17Protocol::EncodeLastM17Packet(SM17Frame &frame, const CDvHeaderPacket &Header, const CDvFramePacket &DvFrame, uint32_t iSeq) const
{
EncodeM17Packet(frame, Header, DvFrame, iSeq);
frame.framenumber = htons(ntohs(frame.framenumber) | 0x8000U);
}

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