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network/discovery: Add to DHT only peers that support genesis-based p…
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…rotocol (#3833)

This PR adds to the DHT only the peers that support the genesis/fork/kad
protocol.
Before this PR, any peer that supported the legacy `/kad/[id]` protocol
was added to the DHT.

This is the first step in removing the support for the legacy kad
protocols.

While I have adjusted unit tests to validate the appropriate behavior,
this still needs proper testing in our stack.

Part of #504.

cc @paritytech/networking

---------

Signed-off-by: Alexandru Vasile <[email protected]>
Co-authored-by: Bastian Köcher <[email protected]>
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@lexnv @bkchr
lexnv and bkchr authored May 16, 2024
1 parent 4adfa37 commit 3399bc0
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Showing 2 changed files with 105 additions and 25 deletions.
117 changes: 96 additions & 21 deletions substrate/client/network/src/discovery.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -105,7 +105,8 @@ pub struct DiscoveryConfig {
discovery_only_if_under_num: u64,
enable_mdns: bool,
kademlia_disjoint_query_paths: bool,
kademlia_protocols: Vec<Vec<u8>>,
kademlia_protocol: Vec<u8>,
kademlia_legacy_protocol: Vec<u8>,
kademlia_replication_factor: NonZeroUsize,
}

Expand All @@ -121,7 +122,8 @@ impl DiscoveryConfig {
discovery_only_if_under_num: std::u64::MAX,
enable_mdns: false,
kademlia_disjoint_query_paths: false,
kademlia_protocols: Vec::new(),
kademlia_protocol: Vec::new(),
kademlia_legacy_protocol: Vec::new(),
kademlia_replication_factor: NonZeroUsize::new(DEFAULT_KADEMLIA_REPLICATION_FACTOR)
.expect("value is a constant; constant is non-zero; qed."),
}
Expand Down Expand Up @@ -177,9 +179,8 @@ impl DiscoveryConfig {
fork_id: Option<&str>,
protocol_id: &ProtocolId,
) -> &mut Self {
self.kademlia_protocols = Vec::new();
self.kademlia_protocols.push(kademlia_protocol_name(genesis_hash, fork_id));
self.kademlia_protocols.push(legacy_kademlia_protocol_name(protocol_id));
self.kademlia_protocol = kademlia_protocol_name(genesis_hash, fork_id);
self.kademlia_legacy_protocol = legacy_kademlia_protocol_name(protocol_id);
self
}

Expand Down Expand Up @@ -207,14 +208,19 @@ impl DiscoveryConfig {
discovery_only_if_under_num,
enable_mdns,
kademlia_disjoint_query_paths,
kademlia_protocols,
kademlia_protocol,
kademlia_legacy_protocol,
kademlia_replication_factor,
} = self;

let kademlia = if !kademlia_protocols.is_empty() {
let kademlia = if !kademlia_protocol.is_empty() {
let mut config = KademliaConfig::default();

config.set_replication_factor(kademlia_replication_factor);
// Populate kad with both the legacy and the new protocol names.
// Remove the legacy protocol:
// https://github.com/paritytech/polkadot-sdk/issues/504
let kademlia_protocols = [kademlia_protocol.clone(), kademlia_legacy_protocol];
config.set_protocol_names(kademlia_protocols.into_iter().map(Into::into).collect());
// By default Kademlia attempts to insert all peers into its routing table once a
// dialing attempt succeeds. In order to control which peer is added, disable the
Expand Down Expand Up @@ -266,6 +272,7 @@ impl DiscoveryConfig {
.expect("value is a constant; constant is non-zero; qed."),
),
records_to_publish: Default::default(),
kademlia_protocol,
}
}
}
Expand Down Expand Up @@ -309,6 +316,11 @@ pub struct DiscoveryBehaviour {
/// did not return the record(in `FinishedWithNoAdditionalRecord`). We will then put the record
/// to these peers.
records_to_publish: HashMap<QueryId, Record>,
/// The chain based kademlia protocol name (including genesis hash and fork id).
///
/// Remove when all nodes are upgraded to genesis hash and fork ID-based Kademlia:
/// <https://github.com/paritytech/polkadot-sdk/issues/504>.
kademlia_protocol: Vec<u8>,
}

impl DiscoveryBehaviour {
Expand Down Expand Up @@ -366,23 +378,29 @@ impl DiscoveryBehaviour {
return
}

if let Some(matching_protocol) = supported_protocols
// The supported protocols must include the chain-based Kademlia protocol.
//
// Extract the chain-based Kademlia protocol from `kademlia.protocol_name()`
// when all nodes are upgraded to genesis hash and fork ID-based Kademlia:
// https://github.com/paritytech/polkadot-sdk/issues/504.
if !supported_protocols
.iter()
.find(|p| kademlia.protocol_names().iter().any(|k| k.as_ref() == p.as_ref()))
.any(|p| p.as_ref() == self.kademlia_protocol.as_slice())
{
trace!(
target: "sub-libp2p",
"Adding self-reported address {} from {} to Kademlia DHT {}.",
addr, peer_id, String::from_utf8_lossy(matching_protocol.as_ref()),
);
kademlia.add_address(peer_id, addr.clone());
} else {
trace!(
target: "sub-libp2p",
"Ignoring self-reported address {} from {} as remote node is not part of the \
Kademlia DHT supported by the local node.", addr, peer_id,
);
return
}

trace!(
target: "sub-libp2p",
"Adding self-reported address {} from {} to Kademlia DHT.",
addr, peer_id
);
kademlia.add_address(peer_id, addr.clone());
}
}

Expand Down Expand Up @@ -1075,17 +1093,20 @@ mod tests {
.unwrap();
// Test both genesis hash-based and legacy
// protocol names.
let protocol_name = if swarm_n % 2 == 0 {
kademlia_protocol_name(genesis_hash, fork_id)
let protocol_names = if swarm_n % 2 == 0 {
vec![kademlia_protocol_name(genesis_hash, fork_id)]
} else {
legacy_kademlia_protocol_name(&protocol_id)
vec![
legacy_kademlia_protocol_name(&protocol_id),
kademlia_protocol_name(genesis_hash, fork_id),
]
};
swarms[swarm_n]
.0
.behaviour_mut()
.add_self_reported_address(
&other,
&[protocol_name],
protocol_names.as_slice(),
addr,
);

Expand Down Expand Up @@ -1181,9 +1202,56 @@ mod tests {
&[kademlia_protocol_name(supported_genesis_hash, None)],
remote_addr.clone(),
);
{
let kademlia = discovery.kademlia.as_mut().unwrap();
assert!(
!kademlia
.kbucket(remote_peer_id)
.expect("Remote peer id not to be equal to local peer id.")
.is_empty(),
"Expect peer with supported protocol to be added."
);
}

let unsupported_peer_id = predictable_peer_id(b"00000000000000000000000000000002");
let unsupported_peer_addr: Multiaddr = "/memory/2".parse().unwrap();

// Check the unsupported peer is not present before and after the call.
{
let kademlia = discovery.kademlia.as_mut().unwrap();
assert!(
kademlia
.kbucket(unsupported_peer_id)
.expect("Remote peer id not to be equal to local peer id.")
.is_empty(),
"Expect unsupported peer not to be added."
);
}
// Note: legacy protocol is not supported without genesis hash and fork ID,
// if the legacy is the only protocol supported, then the peer will not be added.
discovery.add_self_reported_address(
&unsupported_peer_id,
&[legacy_kademlia_protocol_name(&supported_protocol_id)],
unsupported_peer_addr.clone(),
);
{
let kademlia = discovery.kademlia.as_mut().unwrap();
assert!(
kademlia
.kbucket(unsupported_peer_id)
.expect("Remote peer id not to be equal to local peer id.")
.is_empty(),
"Expect unsupported peer not to be added."
);
}

// Supported legacy and genesis based protocols are allowed to be added.
discovery.add_self_reported_address(
&another_peer_id,
&[legacy_kademlia_protocol_name(&supported_protocol_id)],
&[
legacy_kademlia_protocol_name(&supported_protocol_id),
kademlia_protocol_name(supported_genesis_hash, None),
],
another_addr.clone(),
);

Expand All @@ -1194,6 +1262,13 @@ mod tests {
kademlia.kbuckets().fold(0, |acc, bucket| acc + bucket.num_entries()),
"Expect peers with supported protocol to be added."
);
assert!(
!kademlia
.kbucket(another_peer_id)
.expect("Remote peer id not to be equal to local peer id.")
.is_empty(),
"Expect peer with supported protocol to be added."
);
}
}
}
13 changes: 9 additions & 4 deletions substrate/client/network/src/litep2p/discovery.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -268,10 +268,10 @@ impl Discovery {
allow_non_global_addresses: config.allow_non_globals_in_dht,
public_addresses: config.public_addresses.iter().cloned().collect(),
next_kad_query: Some(Delay::new(KADEMLIA_QUERY_INTERVAL)),
local_protocols: HashSet::from_iter([
kademlia_protocol_name(genesis_hash, fork_id),
legacy_kademlia_protocol_name(protocol_id),
]),
local_protocols: HashSet::from_iter([kademlia_protocol_name(
genesis_hash,
fork_id,
)]),
},
ping_config,
identify_config,
Expand All @@ -295,6 +295,11 @@ impl Discovery {
addresses: Vec<Multiaddr>,
) {
if self.local_protocols.is_disjoint(&supported_protocols) {
log::trace!(
target: "sub-libp2p",
"Ignoring self-reported address of peer {peer} as remote node is not part of the \
Kademlia DHT supported by the local node.",
);
return
}

Expand Down

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