code.octet-stream.net Git - m17rt/blob - m17core/src/protocol.rs

   1 use crate::address::{encode_address, Address};
   2
   3 pub(crate) const LSF_SYNC: [i8; 8] = [1, 1, 1, 1, -1, -1, 1, -1];
   4 pub(crate) const BERT_SYNC: [i8; 8] = [-1, 1, -1, -1, 1, 1, 1, 1];
   5 pub(crate) const STREAM_SYNC: [i8; 8] = [-1, -1, -1, -1, 1, 1, -1, 1];
   6 pub(crate) const PACKET_SYNC: [i8; 8] = [1, -1, 1, 1, -1, -1, -1, -1];
   7
   8 #[derive(Debug, Clone, PartialEq, Eq, Copy)]
   9 pub enum Mode {
  10     Packet,
  11     Stream,
  12 }
  13 #[derive(Debug, Clone, PartialEq, Eq, Copy)]
  14 pub enum DataType {
  15     Reserved,
  16     Data,
  17     Voice,
  18     VoiceAndData,
  19 }
  20 #[derive(Debug, Clone, PartialEq, Eq, Copy)]
  21 pub enum EncryptionType {
  22     None,
  23     Scrambler,
  24     Aes,
  25     Other,
  26 }
  27
  28 #[derive(Debug, Clone, PartialEq, Eq)]
  29 pub enum Frame {
  30     Lsf(LsfFrame),
  31     Stream(StreamFrame),
  32     Packet(PacketFrame),
  33     // BERT
  34 }
  35
  36 #[derive(Debug, Clone, PartialEq, Eq, Copy)]
  37 pub enum PacketType {
  38     /// RAW
  39     Raw,
  40     /// AX.25
  41     Ax25,
  42     /// APRS
  43     Aprs,
  44     /// 6LoWPAN
  45     SixLowPan,
  46     /// IPv4
  47     Ipv4,
  48     /// SMS
  49     Sms,
  50     /// Winlink
  51     Winlink,
  52     /// Custom identifier
  53     Other(char),
  54 }
  55
  56 impl PacketType {
  57     pub fn from_proto(buf: &[u8]) -> Option<(Self, usize)> {
  58         buf.utf8_chunks()
  59             .next()
  60             .and_then(|chunk| chunk.valid().chars().next())
  61             .map(|c| match c as u32 {
  62                 0x00 => (PacketType::Raw, 1),
  63                 0x01 => (PacketType::Ax25, 1),
  64                 0x02 => (PacketType::Aprs, 1),
  65                 0x03 => (PacketType::SixLowPan, 1),
  66                 0x04 => (PacketType::Ipv4, 1),
  67                 0x05 => (PacketType::Sms, 1),
  68                 0x06 => (PacketType::Winlink, 1),
  69                 _ => (PacketType::Other(c), c.len_utf8()),
  70             })
  71     }
  72
  73     pub fn as_proto(&self) -> ([u8; 4], usize) {
  74         match self {
  75             PacketType::Raw => ([0, 0, 0, 0], 1),
  76             PacketType::Ax25 => ([1, 0, 0, 0], 1),
  77             PacketType::Aprs => ([2, 0, 0, 0], 1),
  78             PacketType::SixLowPan => ([3, 0, 0, 0], 1),
  79             PacketType::Ipv4 => ([4, 0, 0, 0], 1),
  80             PacketType::Sms => ([5, 0, 0, 0], 1),
  81             PacketType::Winlink => ([6, 0, 0, 0], 1),
  82             PacketType::Other(c) => {
  83                 let mut buf = [0u8; 4];
  84                 let s = c.encode_utf8(&mut buf);
  85                 let len = s.len();
  86                 (buf, len)
  87             }
  88         }
  89     }
  90 }
  91
  92 #[derive(Debug, Clone, PartialEq, Eq)]
  93 pub struct LsfFrame(pub [u8; 30]);
  94
  95 impl LsfFrame {
  96     pub fn new_voice(source: &Address, destination: &Address) -> Self {
  97         let mut out = Self([0u8; 30]);
  98         out.set_source(source);
  99         out.set_destination(destination);
 100         out.set_mode(Mode::Stream);
 101         out.set_data_type(DataType::Voice);
 102         out.set_encryption_type(EncryptionType::None);
 103         out
 104     }
 105
 106     pub fn new_packet(source: &Address, destination: &Address) -> Self {
 107         let mut out = Self([0u8; 30]);
 108         out.set_source(source);
 109         out.set_destination(destination);
 110         out.set_mode(Mode::Packet);
 111         out.set_data_type(DataType::Data);
 112         out.set_encryption_type(EncryptionType::None);
 113         out
 114     }
 115
 116     /// Calculate crc of entire frame. If zero, it is a valid frame.
 117     pub fn check_crc(&self) -> u16 {
 118         crate::crc::m17_crc(&self.0)
 119     }
 120
 121     pub fn destination(&self) -> Address {
 122         crate::address::decode_address((&self.0[0..6]).try_into().unwrap())
 123     }
 124
 125     pub fn source(&self) -> Address {
 126         crate::address::decode_address((&self.0[6..12]).try_into().unwrap())
 127     }
 128
 129     pub fn mode(&self) -> Mode {
 130         if self.lsf_type() & 0x0001 > 0 {
 131             Mode::Stream
 132         } else {
 133             Mode::Packet
 134         }
 135     }
 136
 137     pub fn data_type(&self) -> DataType {
 138         match (self.0[12] >> 1) & 0x03 {
 139             0b00 => DataType::Reserved,
 140             0b01 => DataType::Data,
 141             0b10 => DataType::Voice,
 142             0b11 => DataType::VoiceAndData,
 143             _ => unreachable!(),
 144         }
 145     }
 146
 147     pub fn encryption_type(&self) -> EncryptionType {
 148         match (self.lsf_type() >> 3) & 0x0003 {
 149             0b00 => EncryptionType::None,
 150             0b01 => EncryptionType::Scrambler,
 151             0b10 => EncryptionType::Aes,
 152             0b11 => EncryptionType::Other,
 153             _ => unreachable!(),
 154         }
 155     }
 156
 157     // TODO: encryption sub-type
 158
 159     pub fn channel_access_number(&self) -> u8 {
 160         ((self.lsf_type() >> 7) & 0x000f) as u8
 161     }
 162
 163     pub fn meta(&self) -> [u8; 14] {
 164         self.0[14..28].try_into().unwrap()
 165     }
 166
 167     pub fn set_destination(&mut self, destination: &Address) {
 168         self.0[0..6].copy_from_slice(&encode_address(&destination));
 169         self.recalculate_crc();
 170     }
 171
 172     pub fn set_source(&mut self, source: &Address) {
 173         self.0[6..12].copy_from_slice(&encode_address(&source));
 174         self.recalculate_crc();
 175     }
 176
 177     pub fn set_mode(&mut self, mode: Mode) {
 178         let existing_type = self.lsf_type();
 179         let new_type = (existing_type & !0x0001) | if mode == Mode::Stream { 1 } else { 0 };
 180         self.0[12..14].copy_from_slice(&new_type.to_be_bytes());
 181         self.recalculate_crc();
 182     }
 183
 184     pub fn set_data_type(&mut self, data_type: DataType) {
 185         let type_part = match data_type {
 186             DataType::Reserved => 0b00 << 1,
 187             DataType::Data => 0b01 << 1,
 188             DataType::Voice => 0b10 << 1,
 189             DataType::VoiceAndData => 0b11 << 1,
 190         };
 191         let existing_type = self.lsf_type();
 192         let new_type = (existing_type & !0x0006) | type_part;
 193         self.0[12..14].copy_from_slice(&new_type.to_be_bytes());
 194         self.recalculate_crc();
 195     }
 196
 197     pub fn set_encryption_type(&mut self, encryption_type: EncryptionType) {
 198         let type_part = match encryption_type {
 199             EncryptionType::None => 0b00 << 3,
 200             EncryptionType::Scrambler => 0b01 << 3,
 201             EncryptionType::Aes => 0b10 << 3,
 202             EncryptionType::Other => 0b11 << 3,
 203         };
 204         let existing_type = self.lsf_type();
 205         let new_type = (existing_type & !0x0018) | type_part;
 206         self.0[12..14].copy_from_slice(&new_type.to_be_bytes());
 207         self.recalculate_crc();
 208     }
 209
 210     fn recalculate_crc(&mut self) {
 211         let new_crc = crate::crc::m17_crc(&self.0[0..28]);
 212         self.0[28..30].copy_from_slice(&new_crc.to_be_bytes());
 213         debug_assert_eq!(self.check_crc(), 0);
 214     }
 215
 216     fn lsf_type(&self) -> u16 {
 217         u16::from_be_bytes([self.0[12], self.0[13]])
 218     }
 219 }
 220
 221 #[derive(Debug, Clone, PartialEq, Eq, Default)]
 222 pub struct StreamFrame {
 223     /// Which LICH segment is given in this frame, from 0 to 5 inclusive
 224     pub lich_idx: u8,
 225     /// Decoded LICH segment
 226     pub lich_part: [u8; 5],
 227     /// Which frame in the transmission this is, starting from 0
 228     pub frame_number: u16,
 229     /// Is this the last frame in the transmission?
 230     pub end_of_stream: bool,
 231     /// Raw application data in this frame
 232     pub stream_data: [u8; 16],
 233 }
 234
 235 #[derive(Debug, Clone, PartialEq, Eq)]
 236 pub struct PacketFrame {
 237     /// Application packet payload (chunk)
 238     pub payload: [u8; 25],
 239
 240     /// Frame counter, which provides different information depending on whether this is the last frame or not.
 241     pub counter: PacketFrameCounter,
 242 }
 243
 244 #[derive(Debug, Clone, PartialEq, Eq)]
 245 pub enum PacketFrameCounter {
 246     /// Any packet frame that comes after the LSF and is not the final frame.
 247     Frame {
 248         /// Which frame this is in the superframe, from 0 to 31 inclusive.
 249         ///
 250         /// If a 33rd frame exists (index 32), it will be a `FinalFrame` instead.
 251         ///
 252         /// All 25 bytes of of `payload` are filled and valid.
 253         index: usize,
 254     },
 255     /// The final frame in the packet superframe.
 256     FinalFrame {
 257         /// The number of bytes in `payload` that are filled.
 258         payload_len: usize,
 259     },
 260 }
 261
 262 pub struct LichCollection([Option<[u8; 5]>; 6]);
 263
 264 impl LichCollection {
 265     pub fn new() -> Self {
 266         Self([None; 6])
 267     }
 268
 269     pub fn valid_segments(&self) -> usize {
 270         self.0.iter().filter(|s| s.is_some()).count()
 271     }
 272
 273     pub fn set_segment(&mut self, counter: u8, part: [u8; 5]) {
 274         self.0[counter as usize] = Some(part);
 275     }
 276
 277     pub fn try_assemble(&self) -> Option<[u8; 30]> {
 278         let mut out = [0u8; 30];
 279         for (i, segment) in self.0.iter().enumerate() {
 280             let Some(segment) = segment else {
 281                 return None;
 282             };
 283             for (j, seg_val) in segment.iter().enumerate() {
 284                 out[i * 5 + j] = *seg_val;
 285             }
 286         }
 287         Some(out)
 288     }
 289 }
 290
 291 impl Default for LichCollection {
 292     fn default() -> Self {
 293         Self::new()
 294     }
 295 }