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//! Encoding and decoding for relay messages
//!
//! Relay messages are sent along circuits, inside RELAY or RELAY_EARLY
//! cells.
use super::msg;
use caret::caret_int;
use tor_bytes::{EncodeResult, Error, Result};
use tor_bytes::{Reader, Writer};
caret_int! {
/// The type of the introduction point auth key
pub struct AuthKeyType(u8) {
/// Ed25519; SHA3-256
ED25519_SHA3_256 = 2,
}
}
/// A hidden services establishes a new introduction point,
/// by sending an EstablishIntro message.
#[derive(Debug, Clone)]
pub struct EstablishIntro {
/// Introduction point auth key type and the type of
/// the MAC used in `handshake_auth`.
auth_key_type: AuthKeyType,
/// The public introduction point auth key.
auth_key: Vec<u8>,
/// the MAC of all earlier fields in the cell.
handshake_auth: [u8; 32],
/// A signature using `auth_key` of all contents
/// of the cell.
sig: Vec<u8>,
}
impl msg::Body for EstablishIntro {
fn into_message(self) -> msg::RelayMsg {
msg::RelayMsg::EstablishIntro(self)
}
fn decode_from_reader(r: &mut Reader<'_>) -> Result<Self> {
let auth_key_type = r.take_u8()?.into();
let auth_key_len = r.take_u16()?;
let auth_key = r.take(auth_key_len as usize)?.into();
if r.take_u8()? != 0 {
// TODO: Support ESTABLISH_INTRO extensions
return Err(Error::BadMessage(
"ESTABLISH_INTRO extension not supported.",
));
}
let handshake_auth = r.extract()?;
let sig_len = r.take_u16()?;
let sig = r.take(sig_len as usize)?.into();
Ok(EstablishIntro {
auth_key_type,
auth_key,
handshake_auth,
sig,
})
}
fn encode_onto(self, w: &mut Vec<u8>) -> EncodeResult<()> {
w.write_u8(self.auth_key_type.get());
// TODO: This should fail when auth_key is too long,
// but `as` truncates the value silently. This depends on
// `tor_bytes::Writer::write` to return a `Result`.
w.write_u16(self.auth_key.len() as u16);
w.write_all(&self.auth_key[..]);
// N_EXTENSIONS is zero for now
w.write_u8(0_u8);
w.write_all(&self.handshake_auth[..]);
w.write_u16(self.sig.len() as u16);
w.write_all(&self.sig[..]);
Ok(())
}
}
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