sc-network-bitswap 0.38.0

Substrate Bitswap client/server service
Documentation 
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// Copyright (C) Parity Technologies (UK) Ltd.
// This file is part of Substrate.
// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0

// Substrate 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.

// Substrate 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 Substrate. If not, see <https://www.gnu.org/licenses/>.

//! Bitswap client and server.

use cid::Version as CidVersion;

mod handle;
mod metrics;
mod service;

pub use cid::Cid;
pub(crate) use handle::BitswapCommand;
pub use handle::{BitswapError, BitswapHandle, FetchItem};
pub use service::start;

pub(crate) const LOG_TARGET: &str = "sub-libp2p::bitswap";

/// Maximum entries per Bitswap message.
pub const MAX_WANTED_BLOCKS: usize = 16;

/// IPFS raw multicodec used for indexed transaction payload bytes.
pub const RAW_CODEC: u64 = 0x55;

/// Multihash code for BLAKE2b-256, per the multicodec table.
pub const BLAKE2B_256_MULTIHASH_CODE: u64 = 0xb220;

/// Multihash code for SHA2-256, per the multicodec table.
pub const SHA2_256_MULTIHASH_CODE: u64 = 0x12;

/// Multihash code for Keccak-256, per the multicodec table.
pub const KECCAK_256_MULTIHASH_CODE: u64 = 0x1b;

/// Returns whether Bitswap supports a CID.
pub fn is_cid_supported(cid: &Cid) -> bool {
	cid.version() != CidVersion::V0 &&
		cid.hash().size() == 32 &&
		matches!(
			cid.hash().code(),
			BLAKE2B_256_MULTIHASH_CODE | SHA2_256_MULTIHASH_CODE | KECCAK_256_MULTIHASH_CODE
		)
}

#[cfg(test)]
mod tests {
	use super::*;

	#[test]
	fn is_cid_supported_accepts_all_three_supported_hashings() {
		use cid::multihash::Multihash;
		for multihash_code in
			[BLAKE2B_256_MULTIHASH_CODE, SHA2_256_MULTIHASH_CODE, KECCAK_256_MULTIHASH_CODE]
		{
			let digest = [9u8; 32];
			let mh = Multihash::<64>::wrap(multihash_code, &digest).unwrap();
			let cid = Cid::new_v1(RAW_CODEC, mh);
			assert!(is_cid_supported(&cid), "{multihash_code} CID should be supported");
		}
	}

	#[test]
	fn is_cid_supported_rejects_unknown_multihash_code() {
		use cid::multihash::Multihash;
		let digest = [9u8; 32];
		let mh = Multihash::<64>::wrap(0x99, &digest).unwrap();
		let cid = Cid::new_v1(RAW_CODEC, mh);
		assert!(!is_cid_supported(&cid));
	}
}