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

   1 use crate::{
   2     address::{encode_address, Address},
   3     bits::BitsMut,
   4 };
   5
   6 pub(crate) const LSF_SYNC: [i8; 8] = [1, 1, 1, 1, -1, -1, 1, -1];
   7 pub(crate) const BERT_SYNC: [i8; 8] = [-1, 1, -1, -1, 1, 1, 1, 1];
   8 pub(crate) const STREAM_SYNC: [i8; 8] = [-1, -1, -1, -1, 1, 1, -1, 1];
   9 pub(crate) const PACKET_SYNC: [i8; 8] = [1, -1, 1, 1, -1, -1, -1, -1];
  10 pub(crate) const PREAMBLE: [i8; 8] = [1, -1, 1, -1, 1, -1, 1, -1];
  11 pub(crate) const END_OF_TRANSMISSION: [i8; 8] = [1, 1, 1, 1, 1, 1, -1, 1];
  12
  13 #[derive(Debug, Clone, PartialEq, Eq, Copy)]
  14 pub enum Mode {
  15     Packet,
  16     Stream,
  17 }
  18 #[derive(Debug, Clone, PartialEq, Eq, Copy)]
  19 pub enum DataType {
  20     Reserved,
  21     Data,
  22     Voice,
  23     VoiceAndData,
  24 }
  25 #[derive(Debug, Clone, PartialEq, Eq, Copy)]
  26 pub enum EncryptionType {
  27     None,
  28     Scrambler,
  29     Aes,
  30     Other,
  31 }
  32
  33 #[derive(Debug, Clone, PartialEq, Eq)]
  34 pub enum Frame {
  35     Lsf(LsfFrame),
  36     Stream(StreamFrame),
  37     Packet(PacketFrame),
  38     // BERT
  39 }
  40
  41 #[derive(Debug, Clone, PartialEq, Eq, Copy)]
  42 pub enum PacketType {
  43     /// RAW
  44     Raw,
  45     /// AX.25
  46     Ax25,
  47     /// APRS
  48     Aprs,
  49     /// 6LoWPAN
  50     SixLowPan,
  51     /// IPv4
  52     Ipv4,
  53     /// SMS
  54     Sms,
  55     /// Winlink
  56     Winlink,
  57     /// Custom identifier
  58     Other(char),
  59 }
  60
  61 impl PacketType {
  62     pub fn from_proto(buf: &[u8]) -> Option<(Self, usize)> {
  63         buf.utf8_chunks()
  64             .next()
  65             .and_then(|chunk| chunk.valid().chars().next())
  66             .map(|c| match c as u32 {
  67                 0x00 => (PacketType::Raw, 1),
  68                 0x01 => (PacketType::Ax25, 1),
  69                 0x02 => (PacketType::Aprs, 1),
  70                 0x03 => (PacketType::SixLowPan, 1),
  71                 0x04 => (PacketType::Ipv4, 1),
  72                 0x05 => (PacketType::Sms, 1),
  73                 0x06 => (PacketType::Winlink, 1),
  74                 _ => (PacketType::Other(c), c.len_utf8()),
  75             })
  76     }
  77
  78     pub fn as_proto(&self) -> ([u8; 4], usize) {
  79         match self {
  80             PacketType::Raw => ([0, 0, 0, 0], 1),
  81             PacketType::Ax25 => ([1, 0, 0, 0], 1),
  82             PacketType::Aprs => ([2, 0, 0, 0], 1),
  83             PacketType::SixLowPan => ([3, 0, 0, 0], 1),
  84             PacketType::Ipv4 => ([4, 0, 0, 0], 1),
  85             PacketType::Sms => ([5, 0, 0, 0], 1),
  86             PacketType::Winlink => ([6, 0, 0, 0], 1),
  87             PacketType::Other(c) => {
  88                 let mut buf = [0u8; 4];
  89                 let s = c.encode_utf8(&mut buf);
  90                 let len = s.len();
  91                 (buf, len)
  92             }
  93         }
  94     }
  95 }
  96
  97 #[derive(Debug, Clone, PartialEq, Eq)]
  98 pub struct LsfFrame(pub [u8; 30]);
  99
 100 impl LsfFrame {
 101     pub fn new_voice(source: &Address, destination: &Address) -> Self {
 102         let mut out = Self([0u8; 30]);
 103         out.set_source(source);
 104         out.set_destination(destination);
 105         out.set_mode(Mode::Stream);
 106         out.set_data_type(DataType::Voice);
 107         out.set_encryption_type(EncryptionType::None);
 108         out
 109     }
 110
 111     pub fn new_packet(source: &Address, destination: &Address) -> Self {
 112         let mut out = Self([0u8; 30]);
 113         out.set_source(source);
 114         out.set_destination(destination);
 115         out.set_mode(Mode::Packet);
 116         out.set_data_type(DataType::Data);
 117         out.set_encryption_type(EncryptionType::None);
 118         out
 119     }
 120
 121     /// Calculate crc of entire frame. If zero, it is a valid frame.
 122     pub fn check_crc(&self) -> u16 {
 123         crate::crc::m17_crc(&self.0)
 124     }
 125
 126     pub fn destination(&self) -> Address {
 127         crate::address::decode_address((&self.0[0..6]).try_into().unwrap())
 128     }
 129
 130     pub fn source(&self) -> Address {
 131         crate::address::decode_address((&self.0[6..12]).try_into().unwrap())
 132     }
 133
 134     pub fn mode(&self) -> Mode {
 135         if self.lsf_type() & 0x0001 > 0 {
 136             Mode::Stream
 137         } else {
 138             Mode::Packet
 139         }
 140     }
 141
 142     pub fn data_type(&self) -> DataType {
 143         match (self.0[12] >> 1) & 0x03 {
 144             0b00 => DataType::Reserved,
 145             0b01 => DataType::Data,
 146             0b10 => DataType::Voice,
 147             0b11 => DataType::VoiceAndData,
 148             _ => unreachable!(),
 149         }
 150     }
 151
 152     pub fn encryption_type(&self) -> EncryptionType {
 153         match (self.lsf_type() >> 3) & 0x0003 {
 154             0b00 => EncryptionType::None,
 155             0b01 => EncryptionType::Scrambler,
 156             0b10 => EncryptionType::Aes,
 157             0b11 => EncryptionType::Other,
 158             _ => unreachable!(),
 159         }
 160     }
 161
 162     // TODO: encryption sub-type
 163
 164     pub fn channel_access_number(&self) -> u8 {
 165         ((self.lsf_type() >> 7) & 0x000f) as u8
 166     }
 167
 168     pub fn meta(&self) -> [u8; 14] {
 169         self.0[14..28].try_into().unwrap()
 170     }
 171
 172     pub fn set_destination(&mut self, destination: &Address) {
 173         self.0[0..6].copy_from_slice(&encode_address(destination));
 174         self.recalculate_crc();
 175     }
 176
 177     pub fn set_source(&mut self, source: &Address) {
 178         self.0[6..12].copy_from_slice(&encode_address(source));
 179         self.recalculate_crc();
 180     }
 181
 182     pub fn set_mode(&mut self, mode: Mode) {
 183         let existing_type = self.lsf_type();
 184         let new_type = (existing_type & !0x0001) | if mode == Mode::Stream { 1 } else { 0 };
 185         self.0[12..14].copy_from_slice(&new_type.to_be_bytes());
 186         self.recalculate_crc();
 187     }
 188
 189     pub fn set_data_type(&mut self, data_type: DataType) {
 190         let type_part = match data_type {
 191             DataType::Reserved => 0b00 << 1,
 192             DataType::Data => 0b01 << 1,
 193             DataType::Voice => 0b10 << 1,
 194             DataType::VoiceAndData => 0b11 << 1,
 195         };
 196         let existing_type = self.lsf_type();
 197         let new_type = (existing_type & !0x0006) | type_part;
 198         self.0[12..14].copy_from_slice(&new_type.to_be_bytes());
 199         self.recalculate_crc();
 200     }
 201
 202     pub fn set_encryption_type(&mut self, encryption_type: EncryptionType) {
 203         let type_part = match encryption_type {
 204             EncryptionType::None => 0b00 << 3,
 205             EncryptionType::Scrambler => 0b01 << 3,
 206             EncryptionType::Aes => 0b10 << 3,
 207             EncryptionType::Other => 0b11 << 3,
 208         };
 209         let existing_type = self.lsf_type();
 210         let new_type = (existing_type & !0x0018) | type_part;
 211         self.0[12..14].copy_from_slice(&new_type.to_be_bytes());
 212         self.recalculate_crc();
 213     }
 214
 215     pub fn set_channel_access_number(&mut self, number: u8) {
 216         let mut bits = BitsMut::new(&mut self.0);
 217         bits.set_bit(12 * 8 + 5, (number >> 3) & 1);
 218         bits.set_bit(12 * 8 + 6, (number >> 2) & 1);
 219         bits.set_bit(12 * 8 + 7, (number >> 1) & 1);
 220         bits.set_bit(13 * 8, number & 1);
 221         self.recalculate_crc();
 222     }
 223
 224     fn recalculate_crc(&mut self) {
 225         let new_crc = crate::crc::m17_crc(&self.0[0..28]);
 226         self.0[28..30].copy_from_slice(&new_crc.to_be_bytes());
 227         debug_assert_eq!(self.check_crc(), 0);
 228     }
 229
 230     fn lsf_type(&self) -> u16 {
 231         u16::from_be_bytes([self.0[12], self.0[13]])
 232     }
 233 }
 234
 235 #[derive(Debug, Clone, PartialEq, Eq, Default)]
 236 pub struct StreamFrame {
 237     /// Which LICH segment is given in this frame, from 0 to 5 inclusive
 238     pub lich_idx: u8,
 239     /// Decoded LICH segment
 240     pub lich_part: [u8; 5],
 241     /// Which frame in the transmission this is, starting from 0
 242     pub frame_number: u16,
 243     /// Is this the last frame in the transmission?
 244     pub end_of_stream: bool,
 245     /// Raw application data in this frame
 246     pub stream_data: [u8; 16],
 247 }
 248
 249 #[derive(Debug, Clone, PartialEq, Eq)]
 250 pub struct PacketFrame {
 251     /// Application packet payload (chunk)
 252     pub payload: [u8; 25],
 253
 254     /// Frame counter, which provides different information depending on whether this is the last frame or not.
 255     pub counter: PacketFrameCounter,
 256 }
 257
 258 #[derive(Debug, Clone, PartialEq, Eq)]
 259 pub enum PacketFrameCounter {
 260     /// Any packet frame that comes after the LSF and is not the final frame.
 261     Frame {
 262         /// Which frame this is in the superframe, from 0 to 31 inclusive.
 263         ///
 264         /// If a 33rd frame exists (index 32), it will be a `FinalFrame` instead.
 265         ///
 266         /// All 25 bytes of of `payload` are filled and valid.
 267         index: usize,
 268     },
 269     /// The final frame in the packet superframe.
 270     FinalFrame {
 271         /// The number of bytes in `payload` that are filled.
 272         payload_len: usize,
 273     },
 274 }
 275
 276 pub struct LichCollection([Option<[u8; 5]>; 6]);
 277
 278 impl LichCollection {
 279     pub fn new() -> Self {
 280         Self([None; 6])
 281     }
 282
 283     pub fn valid_segments(&self) -> usize {
 284         self.0.iter().filter(|s| s.is_some()).count()
 285     }
 286
 287     pub fn set_segment(&mut self, counter: u8, part: [u8; 5]) {
 288         self.0[counter as usize] = Some(part);
 289     }
 290
 291     pub fn try_assemble(&self) -> Option<[u8; 30]> {
 292         let mut out = [0u8; 30];
 293         for (i, segment) in self.0.iter().enumerate() {
 294             let Some(segment) = segment else {
 295                 return None;
 296             };
 297             for (j, seg_val) in segment.iter().enumerate() {
 298                 out[i * 5 + j] = *seg_val;
 299             }
 300         }
 301         Some(out)
 302     }
 303 }
 304
 305 impl Default for LichCollection {
 306     fn default() -> Self {
 307         Self::new()
 308     }
 309 }
 310
 311 #[cfg(test)]
 312 mod tests {
 313     use super::*;
 314
 315     #[test]
 316     fn set_can() {
 317         let mut frame = LsfFrame([0u8; 30]);
 318         frame.set_channel_access_number(11);
 319         assert_eq!(frame.channel_access_number(), 11);
 320     }
 321 }