ismp/handlers/
timeout.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
// Copyright (C) Polytope Labs Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! The ISMP request timeout handler

use crate::{
	error::Error,
	events::{Event, TimeoutHandled},
	handlers::{validate_state_machine, MessageResult},
	host::{IsmpHost, StateMachine},
	messaging::{hash_post_response, hash_request, TimeoutMessage},
	router::Response,
};
use alloc::vec::Vec;

/// This function handles timeouts
pub fn handle<H>(host: &H, msg: TimeoutMessage) -> Result<MessageResult, anyhow::Error>
where
	H: IsmpHost,
{
	let consensus_clients = host.consensus_clients();

	let check_state_machine_client = |state_machine: StateMachine| {
		consensus_clients
			.iter()
			.find_map(|client| client.state_machine(state_machine).ok())
			.is_none()
	};

	let results = match msg {
		TimeoutMessage::Post { requests, timeout_proof } => {
			let state_machine = validate_state_machine(host, timeout_proof.height)?;
			let state = host.state_machine_commitment(timeout_proof.height)?;

			for request in &requests {
				// check if the destination chain does not match the proof metadata in which case
				// the proof metadata must be the configured proxy
				// and we must not have a configured state machine client for the destination
				if request.dest_chain() != timeout_proof.height.id.state_id &&
					!(host.is_allowed_proxy(&timeout_proof.height.id.state_id) &&
						check_state_machine_client(request.dest_chain()))
				{
					Err(Error::RequestProxyProhibited { meta: request.into() })?
				}

				// Ensure a commitment exists for all requests in the batch
				let commitment = hash_request::<H>(request);
				if host.request_commitment(commitment).is_err() {
					Err(Error::UnknownRequest { meta: request.into() })?
				}

				if !request.timed_out(state.timestamp()) {
					Err(Error::RequestTimeoutNotElapsed {
						meta: request.into(),
						timeout_timestamp: request.timeout(),
						state_machine_time: state.timestamp(),
					})?
				}
			}

			let keys = state_machine.receipts_state_trie_key(requests.clone().into());
			let values = state_machine.verify_state_proof(host, keys, state, &timeout_proof)?;
			if values.into_iter().any(|(_key, val)| val.is_some()) {
				Err(Error::Custom("Some Requests in the batch have been delivered".into()))?
			}

			let router = host.ismp_router();
			requests
				.into_iter()
				.map(|request| {
					let cb = router.module_for_id(request.source_module())?;
					// Delete commitment to prevent rentrancy attack
					let meta = host.delete_request_commitment(&request)?;
					let mut signer = None;
					// If it was a routed request delete the receipt
					if host.host_state_machine() != request.source_chain() {
						signer = host.delete_request_receipt(&request).ok();
					}
					let res = cb.on_timeout(request.clone().into()).map(|_| {
						let commitment = hash_request::<H>(&request);
						Event::PostRequestTimeoutHandled(TimeoutHandled {
							commitment,
							source: request.source_chain(),
							dest: request.dest_chain(),
						})
					});
					// If module callback failed restore commitment so it can be retried
					if res.is_err() {
						host.store_request_commitment(&request, meta)?;
						// If the request was routed we store it's receipt
						if host.host_state_machine() != request.source_chain() && signer.is_some() {
							host.store_request_receipt(&request, &signer.expect("Infaliible"))?;
						}
					}
					Ok::<_, anyhow::Error>(res)
				})
				.collect::<Result<Vec<_>, _>>()?
		},
		TimeoutMessage::PostResponse { responses, timeout_proof } => {
			let state_machine = validate_state_machine(host, timeout_proof.height)?;
			let state = host.state_machine_commitment(timeout_proof.height)?;
			for response in &responses {
				// check if the destination chain does not match the proof metadata in which case
				// the proof metadata must be the configured proxy
				// and we must not have a configured state machine client for the destination
				if response.dest_chain() != timeout_proof.height.id.state_id &&
					!(host.is_allowed_proxy(&timeout_proof.height.id.state_id) &&
						check_state_machine_client(response.dest_chain()))
				{
					Err(Error::ResponseProxyProhibited {
						meta: Response::Post(response.clone()).into(),
					})?
				}
				// Ensure a commitment exists for all responses in the batch
				let commitment = hash_post_response::<H>(response);
				if host.response_commitment(commitment).is_err() {
					Err(Error::UnknownResponse { meta: Response::Post(response.clone()).into() })?
				}

				if response.timeout() > state.timestamp() {
					Err(Error::RequestTimeoutNotElapsed {
						meta: response.into(),
						timeout_timestamp: response.timeout(),
						state_machine_time: state.timestamp(),
					})?
				}
			}

			let items = responses.iter().map(|r| Into::into(r.clone())).collect::<Vec<Response>>();
			let keys = state_machine.receipts_state_trie_key(items.into());
			let values = state_machine.verify_state_proof(host, keys, state, &timeout_proof)?;
			if values.into_iter().any(|(_key, val)| val.is_some()) {
				Err(Error::Custom("Some responses in the batch have been delivered".into()))?
			}

			let router = host.ismp_router();
			responses
				.into_iter()
				.map(|response| {
					let cb = router.module_for_id(response.source_module())?;
					// Delete commitment to prevent rentrancy
					let meta = host.delete_response_commitment(&response)?;
					// If the response was routed we delete it's receipt
					let mut signer = None;
					if host.host_state_machine() != response.source_chain() {
						signer =
							host.delete_response_receipt(&Response::Post(response.clone())).ok();
					}
					let res = cb.on_timeout(response.clone().into()).map(|_| {
						let commitment = hash_post_response::<H>(&response);
						Event::PostResponseTimeoutHandled(TimeoutHandled {
							commitment,
							source: response.source_chain(),
							dest: response.dest_chain(),
						})
					});
					// If module callback failed restore commitment so it can be retried
					if res.is_err() {
						host.store_response_commitment(&response, meta)?;
						if host.host_state_machine() != response.source_chain() && signer.is_some()
						{
							host.store_response_receipt(
								&Response::Post(response),
								&signer.expect("Infallible"),
							)?;
						}
					}
					Ok::<_, anyhow::Error>(res)
				})
				.collect::<Result<Vec<_>, _>>()?
		},
		TimeoutMessage::Get { requests } => {
			for request in &requests {
				let commitment = hash_request::<H>(request);
				// if we have a commitment, it came from us
				if host.request_commitment(commitment).is_err() {
					Err(Error::UnknownRequest { meta: request.into() })?
				}

				// Ensure the get timeout has elapsed on the host
				if !request.timed_out(host.timestamp()) {
					Err(Error::RequestTimeoutNotElapsed {
						meta: request.into(),
						timeout_timestamp: request.timeout(),
						state_machine_time: host.timestamp(),
					})?
				}
			}

			let router = host.ismp_router();
			requests
				.into_iter()
				.map(|request| {
					let cb = router.module_for_id(request.source_module())?;
					// Delete commitment to prevent reentrancy
					let meta = host.delete_request_commitment(&request)?;
					let res = cb.on_timeout(request.clone().into()).map(|_| {
						let commitment = hash_request::<H>(&request);
						Event::GetRequestTimeoutHandled(TimeoutHandled {
							commitment,
							source: request.source_chain(),
							dest: request.dest_chain(),
						})
					});
					// If module callback failed, restore commitment so it can be retried
					if res.is_err() {
						host.store_request_commitment(&request, meta)?;
					}
					Ok::<_, anyhow::Error>(res)
				})
				.collect::<Result<Vec<_>, _>>()?
		},
	};

	Ok(MessageResult::Timeout(results))
}