referrerpolicy=no-referrer-when-downgrade
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
// Copyright (C) Parity Technologies (UK) Ltd.
// This file is part of Cumulus.

// Cumulus is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Cumulus is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Cumulus.  If not, see <http://www.gnu.org/licenses/>.

//! Cumulus parachain inherent
//!
//! The [`ParachainInherentData`] is the data that is passed by the collator to the parachain
//! runtime. The runtime will use this data to execute messages from other parachains/the relay
//! chain or to read data from the relay chain state. When the parachain is validated by a parachain
//! validator on the relay chain, this data is checked for correctness. If the data passed by the
//! collator to the runtime isn't correct, the parachain candidate is considered invalid.
//!
//! To create a [`ParachainInherentData`] for a specific relay chain block, there exists the
//! `ParachainInherentDataExt` trait in `cumulus-client-parachain-inherent` that helps with this.

#![cfg_attr(not(feature = "std"), no_std)]

extern crate alloc;

use cumulus_primitives_core::{
	relay_chain::{BlakeTwo256, Hash as RelayHash, HashT as _},
	InboundDownwardMessage, InboundHrmpMessage, ParaId, PersistedValidationData,
};

use alloc::{collections::btree_map::BTreeMap, vec::Vec};
use scale_info::TypeInfo;
use sp_inherents::InherentIdentifier;

/// The identifier for the parachain inherent.
pub const INHERENT_IDENTIFIER: InherentIdentifier = *b"sysi1337";

/// The inherent data that is passed by the collator to the parachain runtime.
#[derive(codec::Encode, codec::Decode, sp_core::RuntimeDebug, Clone, PartialEq, TypeInfo)]
pub struct ParachainInherentData {
	pub validation_data: PersistedValidationData,
	/// A storage proof of a predefined set of keys from the relay-chain.
	///
	/// Specifically this witness contains the data for:
	///
	/// - the current slot number at the given relay parent
	/// - active host configuration as per the relay parent,
	/// - the relay dispatch queue sizes
	/// - the list of egress HRMP channels (in the list of recipients form)
	/// - the metadata for the egress HRMP channels
	pub relay_chain_state: sp_trie::StorageProof,
	/// Downward messages in the order they were sent.
	pub downward_messages: Vec<InboundDownwardMessage>,
	/// HRMP messages grouped by channels. The messages in the inner vec must be in order they
	/// were sent. In combination with the rule of no more than one message in a channel per block,
	/// this means `sent_at` is **strictly** greater than the previous one (if any).
	pub horizontal_messages: BTreeMap<ParaId, Vec<InboundHrmpMessage>>,
}

#[cfg(feature = "std")]
#[async_trait::async_trait]
impl sp_inherents::InherentDataProvider for ParachainInherentData {
	async fn provide_inherent_data(
		&self,
		inherent_data: &mut sp_inherents::InherentData,
	) -> Result<(), sp_inherents::Error> {
		inherent_data.put_data(INHERENT_IDENTIFIER, &self)
	}

	async fn try_handle_error(
		&self,
		_: &sp_inherents::InherentIdentifier,
		_: &[u8],
	) -> Option<Result<(), sp_inherents::Error>> {
		None
	}
}

/// This struct provides ability to extend a message queue chain (MQC) and compute a new head.
///
/// MQC is an instance of a [hash chain] applied to a message queue. Using a hash chain it's
/// possible to represent a sequence of messages using only a single hash.
///
/// A head for an empty chain is agreed to be a zero hash.
///
/// An instance is used to track either DMP from the relay chain or HRMP across a channel.
/// But a given instance is never used to track both. Therefore, you should call either
/// `extend_downward` or `extend_hrmp`, but not both methods on a single instance.
///
/// [hash chain]: https://en.wikipedia.org/wiki/Hash_chain
#[derive(Default, Clone, codec::Encode, codec::Decode, scale_info::TypeInfo)]
pub struct MessageQueueChain(RelayHash);

impl MessageQueueChain {
	/// Create a new instance initialized to `hash`.
	pub fn new(hash: RelayHash) -> Self {
		Self(hash)
	}

	/// Extend the hash chain with an HRMP message. This method should be used only when
	/// this chain is tracking HRMP.
	pub fn extend_hrmp(&mut self, horizontal_message: &InboundHrmpMessage) -> &mut Self {
		let prev_head = self.0;
		self.0 = BlakeTwo256::hash_of(&(
			prev_head,
			horizontal_message.sent_at,
			BlakeTwo256::hash_of(&horizontal_message.data),
		));
		self
	}

	/// Extend the hash chain with a downward message. This method should be used only when
	/// this chain is tracking DMP.
	pub fn extend_downward(&mut self, downward_message: &InboundDownwardMessage) -> &mut Self {
		let prev_head = self.0;
		self.0 = BlakeTwo256::hash_of(&(
			prev_head,
			downward_message.sent_at,
			BlakeTwo256::hash_of(&downward_message.msg),
		));
		self
	}

	/// Return the current mead of the message queue hash chain.
	/// This is agreed to be the zero hash for an empty chain.
	pub fn head(&self) -> RelayHash {
		self.0
	}
}