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// standard
use std::clone::Clone;
use std::convert::TryInto;
use std::net::TcpStream;
// extern crates
use bson::doc;
use bson::spec::BinarySubtype;
use bson::{Binary, Bson};
use honk_rpc::honk_rpc::{RequestCookie, Response, Session};
use rand::rngs::OsRng;
use rand::RngCore;
use tor_interface::tor_crypto::*;
// internal crates
use crate::ascii_string::*;
use crate::gosling::*;
//
// Endpoint Client
//
#[derive(thiserror::Error, Debug)]
pub enum Error {
#[error("HonkRPC method failed: {0}")]
HonkRPCFailure(#[from] honk_rpc::honk_rpc::Error),
#[error("client received unexpected response: {0}")]
UnexpectedResponseReceived(String),
#[error("client is in invalid state: {0}")]
InvalidState(String),
#[error("incorrect usage: {0}")]
IncorrectUsage(String),
}
pub(crate) enum EndpointClientEvent {
HandshakeCompleted { stream: TcpStream },
}
#[derive(Debug, PartialEq)]
enum EndpointClientState {
BeginHandshake,
WaitingForServerCookie,
WaitingForProofVerification,
HandshakeComplete,
}
pub(crate) struct EndpointClient {
// session data
rpc: Option<Session<TcpStream>>,
pub server_service_id: V3OnionServiceId,
pub requested_channel: AsciiString,
client_service_id: V3OnionServiceId,
client_ed25519_private: Ed25519PrivateKey,
// state machine data
state: EndpointClientState,
begin_handshake_request_cookie: Option<RequestCookie>,
send_response_request_cookie: Option<RequestCookie>,
}
impl EndpointClient {
fn get_state(&self) -> String {
format!("{{ state: {:?}, begin_handshake_request_cookie: {:?}, send_response_request_cookie: {:?} }}", self.state, self.begin_handshake_request_cookie, self.send_response_request_cookie)
}
pub fn new(
rpc: Session<TcpStream>,
server_service_id: V3OnionServiceId,
requested_channel: AsciiString,
client_ed25519_private: Ed25519PrivateKey,
) -> Self {
Self {
rpc: Some(rpc),
server_service_id,
requested_channel,
client_service_id: V3OnionServiceId::from_private_key(&client_ed25519_private),
client_ed25519_private,
state: EndpointClientState::BeginHandshake,
begin_handshake_request_cookie: None,
send_response_request_cookie: None,
}
}
pub fn update(&mut self) -> Result<Option<EndpointClientEvent>, Error> {
if self.state == EndpointClientState::HandshakeComplete {
return Err(Error::IncorrectUsage("update() may not be called after HandshakeComplete has been returned from previous update() call".to_string()));
}
// update our rpc session
if let Some(rpc) = self.rpc.as_mut() {
rpc.update(None)?;
// client state machine
match (
&self.state,
self.begin_handshake_request_cookie,
self.send_response_request_cookie,
) {
(&EndpointClientState::BeginHandshake, None, None) => {
self.begin_handshake_request_cookie = Some(rpc.client_call(
"gosling_endpoint",
"begin_handshake",
0,
doc! {
"version" : bson::Bson::String(GOSLING_PROTOCOL_VERSION.to_string()),
"client_identity" : bson::Bson::String(self.client_service_id.to_string()),
"channel" : bson::Bson::String(self.requested_channel.to_string()),
},
).unwrap());
self.state = EndpointClientState::WaitingForServerCookie;
Ok(None)
}
(
&EndpointClientState::WaitingForServerCookie,
Some(begin_handshake_request_cookie),
None, // send_response_request_cookie
) => {
if let Some(response) = rpc.client_next_response() {
let result = match response {
Response::Pending { cookie } => {
if cookie == begin_handshake_request_cookie {
return Ok(None);
} else {
return Err(Error::UnexpectedResponseReceived(
"received unexpected pending response".to_string(),
));
}
}
Response::Error { cookie, error_code } => {
if cookie != begin_handshake_request_cookie {
return Err(Error::UnexpectedResponseReceived(format!(
"received unexpected error response; rpc error_code: {}",
error_code
)));
}
return Err(Error::UnexpectedResponseReceived(format!(
"received unexpected rpc error_code: {}",
error_code
)));
}
Response::Success { cookie, result } => {
if cookie == begin_handshake_request_cookie {
result
} else {
return Err(Error::UnexpectedResponseReceived(
"received unexpected success response".to_string(),
));
}
}
};
if let Some(bson::Bson::Document(result)) = result {
if let Some(Bson::Binary(Binary {
subtype: BinarySubtype::Generic,
bytes: server_cookie,
})) = result.get("server_cookie")
{
// build arguments for send_response()
// client_cookie
let mut client_cookie: ClientCookie = Default::default();
OsRng.fill_bytes(&mut client_cookie);
// client_identity_proof_signature
let server_cookie: ServerCookie =
match server_cookie.clone().try_into() {
Ok(server_cookie) => server_cookie,
Err(_) => {
return Err(Error::UnexpectedResponseReceived(format!(
"unable to convert '{:?}' to server cookie",
server_cookie
)))
}
};
let client_identity_proof = build_client_proof(
DomainSeparator::GoslingEndpoint,
&self.requested_channel,
&self.client_service_id,
&self.server_service_id,
&client_cookie,
&server_cookie,
);
let client_identity_proof_signature = self
.client_ed25519_private
.sign_message(&client_identity_proof);
// build our args object for rpc call
let args = doc! {
"client_cookie" : Bson::Binary(bson::Binary{subtype: BinarySubtype::Generic, bytes: client_cookie.to_vec()}),
"client_identity_proof_signature" : Bson::Binary(bson::Binary{subtype: BinarySubtype::Generic, bytes: client_identity_proof_signature.to_bytes().to_vec()}),
};
// make rpc call
self.send_response_request_cookie = Some(
rpc.client_call("gosling_endpoint", "send_response", 0, args)
.unwrap(),
);
self.state = EndpointClientState::WaitingForProofVerification;
} else {
return Err(Error::UnexpectedResponseReceived(format!(
"begin_handshake() returned unexpected value: {}",
result
)));
}
} else {
return Err(Error::UnexpectedResponseReceived(format!(
"begin_handshake() returned unexpected value: {:?}",
result
)));
}
}
Ok(None)
}
(
&EndpointClientState::WaitingForProofVerification,
Some(_begin_handshake_request_cookie),
Some(send_response_request_cookie),
) => {
if let Some(response) = rpc.client_next_response() {
let result = match response {
Response::Pending { cookie } => {
if cookie == send_response_request_cookie {
return Ok(None);
} else {
return Err(Error::UnexpectedResponseReceived(
"received unexpected pending response".to_string(),
));
}
}
Response::Error { cookie, error_code } => {
if cookie == send_response_request_cookie {
return Err(Error::UnexpectedResponseReceived(format!(
"received unexpected error response; rpc error_code: {}",
error_code
)));
}
return Err(Error::UnexpectedResponseReceived(format!(
"received unexpected rpc error_code: {}",
error_code
)));
}
Response::Success { cookie, result } => {
if cookie == send_response_request_cookie {
result
} else {
return Err(Error::UnexpectedResponseReceived(
"received unexpected success response".to_string(),
));
}
}
};
if let Some(Bson::Document(result)) = result {
if result.is_empty() {
self.state = EndpointClientState::HandshakeComplete;
let stream = std::mem::take(&mut self.rpc).unwrap().into_stream();
return Ok(Some(EndpointClientEvent::HandshakeCompleted {
stream,
}));
} else {
return Err(Error::UnexpectedResponseReceived(format!(
"received unexpected data from send_response(): {:?}",
result
)));
}
} else {
return Err(Error::UnexpectedResponseReceived(format!(
"received unexpected data from send_response(): {:?}",
result
)));
}
}
Ok(None)
}
_ => Err(Error::InvalidState(self.get_state())),
}
} else {
Err(Error::InvalidState(self.get_state()))
}
}
}