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make hdlc operations work on slices

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This commit is contained in:
Will Greenberg
2023-12-07 17:20:22 -08:00
parent 470a263593
commit 76555fe68c
2 changed files with 14 additions and 12 deletions
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5
src/diag_device.rs
View File

@@ -95,7 +95,7 @@ impl DiagDevice {
fn parse_response_container(&self, container: MessagesContainer) -> DiagResult<Vec<Message>> {
let mut result = Vec::new();
for msg in container.messages {
match hdlc_decapsulate(msg.data, &self.crc) {
match hdlc_decapsulate(&msg.data, &self.crc) {
Ok(data) => match Message::from_bytes((&data, 0)) {
Ok(((_, leftover_bytes), res)) => {
if leftover_bytes > 0 {
@@ -110,6 +110,7 @@ impl DiagDevice {
},
Err(err) => {
println!("error decapsulating response: {:?}", err);
println!("{:?}", &msg.data);
}
}
}
@@ -138,7 +139,7 @@ impl DiagDevice {
data_type: DataType::UserSpace,
use_mdm: self.use_mdm > 0,
mdm_field: -1,
hdlc_encapsulated_request: hdlc_encapsulate(req.to_bytes().unwrap(), &self.crc),
hdlc_encapsulated_request: hdlc_encapsulate(&req.to_bytes().unwrap(), &self.crc),
}.to_bytes().unwrap();
unsafe {
let fd = self.file.as_raw_fd();

21
src/hdlc.rs
View File

@@ -21,35 +21,36 @@ pub enum HdlcError {
TooShort,
}
pub fn hdlc_encapsulate(mut data: Vec<u8>, crc: &Crc<u16>) -> Vec<u8> {
data.put_u16_le(crc.checksum(&data));
pub fn hdlc_encapsulate(data: &[u8], crc: &Crc<u16>) -> Vec<u8> {
let mut result: Vec<u8> = vec![];
result.put_u16_le(crc.checksum(&data));
let mut result: Vec<u8> = data.iter()
let escaped = data.iter()
.flat_map(|&b| match b {
// TODO: is this too expensive?
0x7e => vec![0x7d, 0x5e],
0x7d => vec![0x7d, 0x5d],
_ => vec![b],
})
.collect();
});
result.extend(escaped);
result.push(0x7e);
result
}
pub fn hdlc_decapsulate(mut data: Vec<u8>, crc: &Crc<u16>) -> Result<Vec<u8>, HdlcError> {
pub fn hdlc_decapsulate(data: &[u8], crc: &Crc<u16>) -> Result<Vec<u8>, HdlcError> {
// TODO: return errors instead of panicking
if data.len() < 3 {
return Err(HdlcError::TooShort);
}
let last_char = data.pop().unwrap(); // safe since len() >= 3
let last_char = data[data.len() - 1]; // safe since len() >= 3
if last_char != 0x7e {
return Err(HdlcError::NoTrailingCharacter(last_char));
}
let mut unescaped = Vec::new();
let mut escaping = false;
for b in data {
for &b in data {
if escaping {
match b {
0x5e => unescaped.push(0x7e),
@@ -84,8 +85,8 @@ mod tests {
let crc = Crc::<u16>::new(&crate::diag_device::CRC_CCITT_ALG);
let data = vec![0x01, 0x02, 0x03, 0x04];
let expected = vec![1, 2, 3, 4, 145, 57, 126];
let encapsulated = hdlc_encapsulate(data.clone(), &crc);
let encapsulated = hdlc_encapsulate(&data, &crc);
assert_eq!(&encapsulated, &expected);
assert_eq!(hdlc_decapsulate(encapsulated, &crc), Ok(data));
assert_eq!(hdlc_decapsulate(&encapsulated, &crc), Ok(data));
}
}