// Encode is called by internal services if the BBMD is also an active device public int Encode(byte[] buffer, int offset, BacnetBvlcV6Functions function, int msgLength, BacnetAddress address) { // offset always 0, we are the first after udp First7BytesHeaderEncode(buffer, function, msgLength); // BBMD service if (function == BacnetBvlcV6Functions.BVLC_ORIGINAL_BROADCAST_NPDU && _bbmdFdServiceActivated) { var me = _myTransport.LocalEndPoint; BacnetIpV6UdpProtocolTransport.Convert(me, out var bacme); Array.Copy(VMAC, bacme.VMac, 3); Forward_NPDU(buffer, msgLength, false, me, bacme); // send to all BBMDs and FDs return(7); // ready to send } if (function != BacnetBvlcV6Functions.BVLC_ORIGINAL_UNICAST_NPDU) { return(0); // ? } buffer[7] = address.VMac[0]; buffer[8] = address.VMac[1]; buffer[9] = address.VMac[2]; return(10); // ready to send }
// Never tested private void Forward_NPDU(byte[] buffer, int msgLength, bool toGlobalBroadcast, IPEndPoint epSender, BacnetAddress bacSender) { // Forms the forwarded NPDU from the original (broadcast npdu), and send it to all // copy, 18 bytes shifted (orignal bvlc header : 7 bytes, new one : 25 bytes) var b = new byte[msgLength + 18]; // normaly only 'small' frames are present here, so no need to check if it's to big for Udp Array.Copy(buffer, 0, b, 18, msgLength); // 7 bytes for the BVLC Header, with the embedded 6 bytes IP:Port of the original sender First7BytesHeaderEncode(b, BacnetBvlcV6Functions.BVLC_FORWARDED_NPDU, msgLength + 18); // replace my Vmac by the orignal source vMac Array.Copy(bacSender.VMac, 0, b, 4, 3); // Add IpV6 endpoint Array.Copy(bacSender.adr, 0, b, 7, 18); // Send To BBMD SendToBBMDs(b, msgLength + 18); // Send To FD, except the sender SendToFDs(b, msgLength + 18, epSender); // Broadcast if required if (toGlobalBroadcast) { IPEndPoint ep; BacnetIpV6UdpProtocolTransport.Convert(_broadcastAdd, out ep); _myTransport.Send(b, msgLength + 18, ep); } }
// quite the same frame as the previous one private void SendAddressResolutionRequest(byte[] vMacDest) { IPEndPoint ep; BacnetIpV6UdpProtocolTransport.Convert(_broadcastAdd, out ep); var b = new byte[10]; First7BytesHeaderEncode(b, BacnetBvlcV6Functions.BVLC_ADDRESS_RESOLUTION, 10); Array.Copy(vMacDest, 0, b, 7, 3); _myTransport.Send(b, 10, ep); }
// Decode is called each time an Udp Frame is received public int Decode(byte[] buffer, int offset, out BacnetBvlcV6Functions function, out int msgLength, IPEndPoint sender, BacnetAddress remoteAddress) { // offset always 0, we are the first after udp // and a previous test by the caller guaranteed at least 4 bytes into the buffer function = (BacnetBvlcV6Functions)buffer[1]; msgLength = (buffer[2] << 8) | (buffer[3] << 0); if (buffer[0] != BVLL_TYPE_BACNET_IPV6 || buffer.Length != msgLength) { return(-1); } Array.Copy(buffer, 4, remoteAddress.VMac, 0, 3); switch (function) { case BacnetBvlcV6Functions.BVLC_RESULT: return(9); // only for the upper layers case BacnetBvlcV6Functions.BVLC_ORIGINAL_UNICAST_NPDU: return(10); // only for the upper layers case BacnetBvlcV6Functions.BVLC_ORIGINAL_BROADCAST_NPDU: // Send to FDs & BBMDs, not broadcast or it will be made twice ! if (_bbmdFdServiceActivated) { Forward_NPDU(buffer, msgLength, false, sender, remoteAddress); } return(7); // also for the upper layers case BacnetBvlcV6Functions.BVLC_ADDRESS_RESOLUTION: // need to verify that the VMAC is mine if (VMAC[0] == buffer[7] && VMAC[1] == buffer[8] && VMAC[2] == buffer[9]) { // coming from myself ? avoid loopback if (!_myTransport.LocalEndPoint.Equals(sender)) { SendAddressResolutionAck(sender, remoteAddress.VMac, BacnetBvlcV6Functions.BVLC_ADDRESS_RESOLUTION_ACK); } } return(0); // not for the upper layers case BacnetBvlcV6Functions.BVLC_FORWARDED_ADDRESS_RESOLUTION: // no need to verify the target VMAC, should be OK SendAddressResolutionAck(sender, remoteAddress.VMac, BacnetBvlcV6Functions.BVLC_ADDRESS_RESOLUTION_ACK); return(0); // not for the upper layers case BacnetBvlcV6Functions.BVLC_ADDRESS_RESOLUTION_ACK: // adresse conflict if (VMAC[0] == buffer[4] && VMAC[1] == buffer[5] && VMAC[2] == buffer[6] && RandomVmac) { new Random().NextBytes(VMAC); VMAC[0] = (byte)((VMAC[0] & 0x7F) | 0x40); SendAddressResolutionRequest(VMAC); } return(0); // not for the upper layers case BacnetBvlcV6Functions.BVLC_VIRTUAL_ADDRESS_RESOLUTION: SendAddressResolutionAck(sender, remoteAddress.VMac, BacnetBvlcV6Functions.BVLC_VIRTUAL_ADDRESS_RESOLUTION_ACK); return(0); // not for the upper layers case BacnetBvlcV6Functions.BVLC_VIRTUAL_ADDRESS_RESOLUTION_ACK: return(0); // not for the upper layers case BacnetBvlcV6Functions.BVLC_FORWARDED_NPDU: if (_myTransport.LocalEndPoint.Equals(sender)) { return(0); } // certainly TODO the same code I've put in the IPV4 implementation if (_bbmdFdServiceActivated && msgLength >= 25) { bool ret; lock (_bbmds) ret = _bbmds.Exists(items => items.Equals(sender)); // verify sender presence in the table // avoid also loopback if (ret) // message from a know BBMD address, sent to all FDs and broadcast { SendToFDs(buffer, msgLength); // send without modification // Assume all BVLC_FORWARDED_NPDU are directly sent to me in the // unicast mode and not by the way of the multicast address // If not, it's not really a big problem, devices on the local net will // receive two times the message (after all it's just WhoIs, Iam, ...) IPEndPoint ep; BacnetIpV6UdpProtocolTransport.Convert(_broadcastAdd, out ep); _myTransport.Send(buffer, msgLength, ep); } } return(25); // for the upper layers case BacnetBvlcV6Functions.BVLC_REGISTER_FOREIGN_DEVICE: if (_bbmdFdServiceActivated && msgLength == 9) { var TTL = (buffer[7] << 8) + buffer[8]; // unit is second RegisterForeignDevice(sender, TTL); SendResult(sender, BacnetBvlcV6Results.SUCCESSFUL_COMPLETION); // ack } return(0); // not for the upper layers case BacnetBvlcV6Functions.BVLC_DELETE_FOREIGN_DEVICE_TABLE_ENTRY: return(0); // not for the upper layers case BacnetBvlcV6Functions.BVLC_SECURE_BVLC: return(0); // not for the upper layers case BacnetBvlcV6Functions.BVLC_DISTRIBUTE_BROADCAST_TO_NETWORK: // Sent by a Foreign Device, not a BBMD if (_bbmdFdServiceActivated) { // Send to FDs except the sender, BBMDs and broadcast lock (_foreignDevices) { if (_foreignDevices.Exists(item => item.Key.Equals(sender))) // verify previous registration { Forward_NPDU(buffer, msgLength, true, sender, remoteAddress); } else { SendResult(sender, BacnetBvlcV6Results.DISTRIBUTE_BROADCAST_TO_NETWORK_NAK); } } } return(0); // not for the upper layers // error encoding function or experimental one default: return(-1); } }