Add a --no-private-ipv4 CLI option (#4042)

* Add a --no-private-ipv4 CLI option

* Fix tests

* Fix tests

substrate/core/network/src/behaviour.rs

@@ -62,11 +62,17 @@ impl<B: BlockT, S: NetworkSpecialization<B>, H: ExHashT> Behaviour<B, S, H> {
 		local_public_key: PublicKey,
 		known_addresses: Vec<(PeerId, Multiaddr)>,
 		enable_mdns: bool,
+		allow_private_ipv4: bool,
 	) -> Self {
 		Behaviour {
 			substrate,
 			debug_info: debug_info::DebugInfoBehaviour::new(user_agent, local_public_key.clone()),
-			discovery: DiscoveryBehaviour::new(local_public_key, known_addresses, enable_mdns),
+			discovery: DiscoveryBehaviour::new(
+				local_public_key,
+				known_addresses,
+				enable_mdns,
+				allow_private_ipv4
+			),
 			events: Vec::new(),
 		}
 	}

substrate/core/network/src/config.rs

@@ -282,6 +282,7 @@ impl Default for NetworkConfiguration {
 			node_name: "unknown".into(),
 			transport: TransportConfig::Normal {
 				enable_mdns: false,
+				allow_private_ipv4: true,
 				wasm_external_transport: None,
 			},
 			max_parallel_downloads: 5,
@@ -327,6 +328,11 @@ pub enum TransportConfig {
 		/// and connect to them if they support the same chain.
 		enable_mdns: bool,
 
+		/// If true, allow connecting to private IPv4 addresses (as defined in
+		/// [RFC1918](https://tools.ietf.org/html/rfc1918)), unless the address has been passed in
+		/// [`NetworkConfiguration::reserved_nodes`] or [`NetworkConfiguration::boot_nodes`].
+		allow_private_ipv4: bool,
+
 		/// Optional external implementation of a libp2p transport. Used in WASM contexts where we
 		/// need some binding between the networking provided by the operating system or environment
 		/// and libp2p.

substrate/core/network/src/discovery.rs

@@ -85,6 +85,9 @@ pub struct DiscoveryBehaviour<TSubstream> {
 	local_peer_id: PeerId,
 	/// Number of nodes we're currently connected to.
 	num_connections: u64,
+	/// If false, `addresses_of_peer` won't return any private IPv4 address, except for the ones
+	/// stored in `user_defined`.
+	allow_private_ipv4: bool,
 }
 
 impl<TSubstream> DiscoveryBehaviour<TSubstream> {
@@ -94,7 +97,8 @@ impl<TSubstream> DiscoveryBehaviour<TSubstream> {
 	pub fn new(
 		local_public_key: PublicKey,
 		user_defined: Vec<(PeerId, Multiaddr)>,
-		enable_mdns: bool
+		enable_mdns: bool,
+		allow_private_ipv4: bool,
 	) -> Self {
 		if enable_mdns {
 			#[cfg(target_os = "unknown")]
@@ -116,6 +120,7 @@ impl<TSubstream> DiscoveryBehaviour<TSubstream> {
 			discoveries: VecDeque::new(),
 			local_peer_id: local_public_key.into_peer_id(),
 			num_connections: 0,
+			allow_private_ipv4,
 			#[cfg(not(target_os = "unknown"))]
 			mdns: if enable_mdns {
 				match Mdns::new() {
@@ -214,9 +219,27 @@ where
 		let mut list = self.user_defined.iter()
 			.filter_map(|(p, a)| if p == peer_id { Some(a.clone()) } else { None })
 			.collect::<Vec<_>>();
-		list.extend(self.kademlia.addresses_of_peer(peer_id));
-		#[cfg(not(target_os = "unknown"))]
-		list.extend(self.mdns.addresses_of_peer(peer_id));
+
+		{
+			let mut list_to_filter = self.kademlia.addresses_of_peer(peer_id);
+			#[cfg(not(target_os = "unknown"))]
+			list_to_filter.extend(self.mdns.addresses_of_peer(peer_id));
+
+			if !self.allow_private_ipv4 {
+				list_to_filter.retain(|addr| {
+					if let Some(Protocol::Ip4(addr)) = addr.iter().next() {
+						if addr.is_private() {
+							return false;
+						}
+					}
+
+					true
+				});
+			}
+
+			list.extend(list_to_filter);
+		}
+
 		trace!(target: "sub-libp2p", "Addresses of {:?} are {:?}", peer_id, list);
 		if list.is_empty() {
 			if self.kademlia.kbuckets_entries().any(|p| p == peer_id) {
@@ -457,7 +480,7 @@ mod tests {
 					upgrade::apply(stream, upgrade, endpoint, libp2p::core::upgrade::Version::V1)
 				});
 
-			let behaviour = DiscoveryBehaviour::new(keypair.public(), user_defined.clone(), false);
+			let behaviour = DiscoveryBehaviour::new(keypair.public(), user_defined.clone(), false, true);
 			let mut swarm = Swarm::new(transport, behaviour, keypair.public().into_peer_id());
 			let listen_addr: Multiaddr = format!("/memory/{}", rand::random::<u64>()).parse().unwrap();
 

substrate/core/network/src/service.rs

@@ -225,7 +225,11 @@ impl<B: BlockT + 'static, S: NetworkSpecialization<B>, H: ExHashT> NetworkWorker
 				match params.network_config.transport {
 					TransportConfig::MemoryOnly => false,
 					TransportConfig::Normal { enable_mdns, .. } => enable_mdns,
-				}
+				},
+				match params.network_config.transport {
+					TransportConfig::MemoryOnly => false,
+					TransportConfig::Normal { allow_private_ipv4, .. } => allow_private_ipv4,
+				},
 			);
 			let (transport, bandwidth) = {
 				let (config_mem, config_wasm) = match params.network_config.transport {