feat: initialize Kurdistan SDK - independent fork of Polkadot SDK

pezkuwi/node/malus/Cargo.toml

@@ -0,0 +1,82 @@
+[package]
+name = "pezkuwi-test-malus"
+description = "Misbehaving nodes for local testnets, system and Simnet tests."
+version = "1.0.0"
+authors.workspace = true
+edition.workspace = true
+license.workspace = true
+readme = "README.md"
+publish = false
+
+[lints]
+workspace = true
+
+[[bin]]
+name = "malus"
+path = "src/malus.rs"
+
+# Use artifact dependencies once stable.
+# See https://github.com/rust-lang/cargo/issues/9096.
+[[bin]]
+name = "pezkuwi-execute-worker"
+path = "../../src/bin/execute-worker.rs"
+# Prevent rustdoc error. Already documented from top-level Cargo.toml.
+doc = false
+[[bin]]
+name = "pezkuwi-prepare-worker"
+path = "../../src/bin/prepare-worker.rs"
+# Prevent rustdoc error. Already documented from top-level Cargo.toml.
+doc = false
+
+[dependencies]
+assert_matches = { workspace = true }
+async-trait = { workspace = true }
+clap = { features = ["derive"], workspace = true }
+color-eyre = { workspace = true }
+futures = { workspace = true }
+gum = { workspace = true, default-features = true }
+pezkuwi-cli = { features = [
+	"malus",
+	"pezkuwichain-native",
+	"zagros-native",
+], workspace = true, default-features = true }
+pezkuwi-erasure-coding = { workspace = true, default-features = true }
+pezkuwi-node-network-protocol = { workspace = true, default-features = true }
+pezkuwi-node-primitives = { workspace = true, default-features = true }
+pezkuwi-node-subsystem = { workspace = true, default-features = true }
+pezkuwi-node-subsystem-types = { workspace = true, default-features = true }
+pezkuwi-node-subsystem-util = { workspace = true, default-features = true }
+pezkuwi-primitives = { workspace = true, default-features = true }
+rand = { workspace = true, default-features = true }
+sp-core = { workspace = true, default-features = true }
+
+# Required for worker binaries to build.
+pezkuwi-node-core-pvf-common = { workspace = true, default-features = true }
+pezkuwi-node-core-pvf-execute-worker = { workspace = true, default-features = true }
+pezkuwi-node-core-pvf-prepare-worker = { workspace = true, default-features = true }
+
+[dev-dependencies]
+futures = { features = ["thread-pool"], workspace = true }
+pezkuwi-node-subsystem-test-helpers = { workspace = true }
+
+[build-dependencies]
+substrate-build-script-utils = { workspace = true, default-features = true }
+
+[features]
+default = []
+fast-runtime = ["pezkuwi-cli/fast-runtime"]
+runtime-benchmarks = [
+	"gum/runtime-benchmarks",
+	"pezkuwi-cli/runtime-benchmarks",
+	"pezkuwi-erasure-coding/runtime-benchmarks",
+	"pezkuwi-node-core-pvf-common/runtime-benchmarks",
+	"pezkuwi-node-core-pvf-execute-worker/runtime-benchmarks",
+	"pezkuwi-node-core-pvf-prepare-worker/runtime-benchmarks",
+	"pezkuwi-node-network-protocol/runtime-benchmarks",
+	"pezkuwi-node-primitives/runtime-benchmarks",
+	"pezkuwi-node-subsystem-test-helpers/runtime-benchmarks",
+	"pezkuwi-node-subsystem-types/runtime-benchmarks",
+	"pezkuwi-node-subsystem-util/runtime-benchmarks",
+	"pezkuwi-node-subsystem/runtime-benchmarks",
+	"pezkuwi-primitives/runtime-benchmarks",
+]

pezkuwi/node/malus/README.md

@@ -0,0 +1,59 @@
+# malus
+
+Create nemesis nodes with alternate, at best faulty, at worst intentionally destructive behavior traits.
+
+The first argument determines the behavior strain. The currently supported are:
+
+* `suggest-garbage-candidate`
+* `back-garbage-candidate`
+* `dispute-ancestor`
+
+## Integration test cases
+
+To define integration tests create file
+in the toml format as used with [zombienet][zombienet]
+under `./integrationtests` describing the network to spawn and
+also the `zndsl` file (with `.zndsl` extension ) using the format
+defined in the [(DSL[(**D**omain **S**pecific **L**anguage)]) doc](https://paritytech.github.io/zombienet/cli/test-dsl-definition-spec.html).
+
+## Usage
+
+> Assumes you already gained permissions, ping in element `@javier:matrix.parity.io` to get access.
+> and you have cloned the [zombienet][zombienet] repo.
+
+To launch a test case in the development cluster use (e.g. for the  ./node/malus/integrationtests/0001-dispute-valid-block.toml):
+
+```sh
+# declare the containers pulled in by zombie-net test definitions
+export MALUS_IMAGE=docker.io/paritypr/malus:4131-ccd09bbf
+export ZOMBIENET_INTEGRATION_TEST_IMAGE=docker.io/paritypr/synth-wave:4131-0.9.12-ccd09bbf-29a1ac18
+export COL_IMAGE=docker.io/paritypr/colander:4131-ccd09bbf
+
+# login chore, once, with the values as provided in the above guide
+gcloud auth login
+gcloud config set project "parity-zombienet"
+gcloud container clusters get-credentials "parity-zombienet" --zone "europe-west3-b" --project parity-zombienet
+
+# launching the actual test
+cd zombienet
+npm run build
+node dist/cli.js test <path to pezkuwi repo>/node/malus/integrationtests/0001-dispute-valid-block.zndsl
+
+# Access  logs (in google cloud storage)
+gsutil ls gs://zombienet-logs/zombie-<namespace uniqueId>/logs/
+```
+
+This will also teardown the namespace after completion.
+
+## Container Image Building Note
+
+In order to build the container image you need to have the latest changes from
+PezkuwiChain and Substrate master branches.
+
+```sh
+pwd # run this from the current dir
+podman build -t paritypr/malus:v1 -f Containerfile ../../..
+```
+
+[zombienet]: https://github.com/paritytech/zombienet
+[gke]: (https://github.com/paritytech/gurke/blob/main/docs/How-to-setup-access-to-gke-k8s-cluster.md)

pezkuwi/node/malus/build.rs

@@ -0,0 +1,22 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+fn main() {
+	substrate_build_script_utils::generate_cargo_keys();
+	// For the node/worker version check, make sure we always rebuild the node and binary workers
+	// when the version changes.
+	substrate_build_script_utils::rerun_if_git_head_changed();
+}

pezkuwi/node/malus/container/Containerfile-cargo-chef

@@ -0,0 +1,155 @@
+#
+### Builder stage
+#
+
+FROM rust as builder
+
+WORKDIR /usr/src/polkadot-malus
+RUN apt-get update && \
+  DEBIAN_FRONTEND=noninteractive apt-get install -y \
+    ca-certificates \
+    clang \
+    curl \
+    cmake \
+    libssl1.1 \
+    libssl-dev \
+    pkg-config
+
+RUN export PATH="$PATH:$HOME/.cargo/bin" && \
+    rustup toolchain install nightly && \
+    rustup target add wasm32-unknown-unknown --toolchain nightly && \
+    rustup default stable
+
+COPY polkadot/  /usr/src/polkadot-malus/polkadot/
+COPY substrate/  /usr/src/polkadot-malus/substrate/
+
+WORKDIR /usr/src/polkadot-malus/polkadot
+
+RUN cargo build -p polkadot-test-malus --release
+RUN cp -v /usr/src/polkadot-malus/polkadot/target/release/malus /usr/local/bin
+
+# check if executable works in this container
+RUN /usr/local/bin/malus $VARIANT --version
+
+#
+### Runtime
+#
+
+FROM debian:buster-slim as runtime
+RUN apt-get update && \
+    apt-get install -y curl tini
+
+COPY --from=builder /usr/src/polkadot-malus/polkadot/target/release/malus /usr/local/bin
+# Non-root user for security purposes.
+#
+# UIDs below 10,000 are a security risk, as a container breakout could result
+# in the container being ran as a more privileged user on the host kernel with
+# the same UID.
+#
+# Static GID/UID is also useful for chown'ing files outside the container where
+# such a user does not exist.
+RUN groupadd --gid 10001 nonroot && \
+    useradd  --home-dir /home/nonroot \
+            --create-home \
+            --shell /bin/bash \
+            --gid nonroot \
+            --groups nonroot \
+            --uid 10000 nonroot
+WORKDIR /home/nonroot/polkadot-malus
+
+RUN chown -R nonroot. /home/nonroot
+
+# Use the non-root user to run our application
+# Tell run test script that it runs in container
+USER nonroot
+# check if executable works in this container
+RUN /usr/local/bin/malus --version
+# Tini allows us to avoid several Docker edge cases, see https://github.com/krallin/tini.
+ENTRYPOINT ["tini", "--", "/usr/local/bin/malus"]
+
+
+
+
+FROM rust:1.54.0 as planner
+WORKDIR /usr/src/polkadot-malus
+# We only pay the installation cost once,
+# it will be cached from the second build onwards
+RUN cargo install cargo-chef
+COPY polkadot/  /usr/src/polkadot-malus/polkadot/
+COPY substrate/  /usr/src/polkadot-malus/substrate/
+WORKDIR /usr/src/polkadot-malus/polkadot
+RUN cargo chef prepare  --recipe-path recipe.json
+
+
+FROM rust:1.54.0 as cacher
+WORKDIR /usr/src/polkadot-malus/polkadot
+RUN cargo install cargo-chef
+RUN apt-get update && \
+  DEBIAN_FRONTEND=noninteractive apt-get install -y \
+    ca-certificates \
+    clang \
+    curl \
+    cmake \
+    libssl1.1 \
+    libssl-dev \
+    pkg-config
+RUN export PATH="$PATH:$HOME/.cargo/bin" && \
+    rustup toolchain install nightly && \
+    rustup target add wasm32-unknown-unknown --toolchain nightly && \
+    rustup default stable
+COPY --from=planner /usr/src/polkadot-malus/polkadot/recipe.json recipe.json
+RUN cargo chef cook --release --recipe-path recipe.json
+
+
+FROM rust:1.54.0 as builder
+WORKDIR /usr/src/polkadot-malus
+COPY polkadot/  /usr/src/polkadot-malus/polkadot/
+COPY substrate/  /usr/src/polkadot-malus/substrate/
+# Copy over the cached dependencies
+WORKDIR /usr/src/polkadot-malus/polkadot
+COPY --from=cacher /usr/src/polkadot-malus/polkadot/target target
+COPY --from=cacher $CARGO_HOME $CARGO_HOME
+RUN apt-get update && \
+  DEBIAN_FRONTEND=noninteractive apt-get install -y \
+    ca-certificates \
+    clang \
+    curl \
+    cmake \
+    libssl1.1 \
+    libssl-dev \
+    pkg-config
+RUN export PATH="$PATH:$HOME/.cargo/bin" && \
+    rustup toolchain install nightly && \
+    rustup target add wasm32-unknown-unknown --toolchain nightly && \
+    rustup default stable
+RUN cargo build -p polkadot-test-malus --release
+
+
+FROM debian:buster-slim as runtime
+RUN apt-get update && \
+    apt-get install -y curl tini
+COPY --from=builder /usr/src/polkadot-malus/polkadot/target/release/malus /usr/local/bin
+# Non-root user for security purposes.
+#
+# UIDs below 10,000 are a security risk, as a container breakout could result
+# in the container being ran as a more privileged user on the host kernel with
+# the same UID.
+#
+# Static GID/UID is also useful for chown'ing files outside the container where
+# such a user does not exist.
+RUN groupadd --gid 10001 nonroot && \
+    useradd  --home-dir /home/nonroot \
+            --create-home \
+            --shell /bin/bash \
+            --gid nonroot \
+            --groups nonroot \
+            --uid 10000 nonroot
+WORKDIR /home/nonroot/polkadot-malus
+RUN chown -R nonroot. /home/nonroot
+# Use the non-root user to run our application
+# Tell run test script that it runs in container
+USER nonroot
+# check if executable works in this container
+RUN /usr/local/bin/malus --version
+# Tini allows us to avoid several Docker edge cases, see https://github.com/krallin/tini.
+ENTRYPOINT ["/usr/local/bin/malus"]

pezkuwi/node/malus/container/build.sh

@@ -0,0 +1 @@
+podman build -t paritypr/malus:v1 -f Containerfile ../../../..

pezkuwi/node/malus/container/malus-local-build.Containerfile

@@ -0,0 +1,66 @@
+#
+### Builder stage
+#
+
+FROM rust as builder
+
+WORKDIR /usr/src/polkadot-malus
+COPY polkadot/  /usr/src/polkadot-malus/polkadot/
+RUN apt-get update && \
+  DEBIAN_FRONTEND=noninteractive apt-get install -y \
+    ca-certificates \
+    clang \
+    curl \
+    cmake \
+    libssl1.1 \
+    libssl-dev \
+    pkg-config
+
+RUN export PATH="$PATH:$HOME/.cargo/bin" && \
+    rustup toolchain install nightly && \
+    rustup target add wasm32-unknown-unknown --toolchain nightly && \
+    rustup default stable
+
+
+WORKDIR /usr/src/polkadot-malus/polkadot
+
+RUN cargo build -p polkadot-test-malus --release --verbose
+RUN cp -v /usr/src/polkadot-malus/polkadot/target/release/malus /usr/local/bin
+
+# check if executable works in this container
+RUN /usr/local/bin/malus --version
+
+#
+### Runtime
+#
+
+FROM debian:buster-slim as runtime
+RUN apt-get update && \
+    apt-get install -y curl tini
+
+COPY --from=builder /usr/src/polkadot-malus/polkadot/target/release/malus /usr/local/bin
+# Non-root user for security purposes.
+#
+# UIDs below 10,000 are a security risk, as a container breakout could result
+# in the container being ran as a more privileged user on the host kernel with
+# the same UID.
+#
+# Static GID/UID is also useful for chown'ing files outside the container where
+# such a user does not exist.
+RUN groupadd --gid 10001 nonroot && \
+    useradd  --home-dir /home/nonroot \
+            --create-home \
+            --shell /bin/bash \
+            --gid nonroot \
+            --groups nonroot \
+            --uid 10000 nonroot
+WORKDIR /home/nonroot/polkadot-malus
+
+RUN chown -R nonroot. /home/nonroot
+
+# Use the non-root user to run our application
+USER nonroot
+# check if executable works in this container
+RUN /usr/local/bin/malus --version
+# Tini allows us to avoid several Docker edge cases, see https://github.com/krallin/tini.
+ENTRYPOINT ["tini", "--", "/usr/local/bin/malus"]

pezkuwi/node/malus/container/pezkuwi-local-build.Containerfile

@@ -0,0 +1,66 @@
+#
+### Builder stage
+#
+
+FROM rust as builder
+
+WORKDIR /usr/src/polkadot
+COPY polkadot/  /usr/src/polkadot
+RUN apt-get update && \
+  DEBIAN_FRONTEND=noninteractive apt-get install -y \
+    ca-certificates \
+    clang \
+    curl \
+    cmake \
+    libssl1.1 \
+    libssl-dev \
+    pkg-config
+
+RUN export PATH="$PATH:$HOME/.cargo/bin" && \
+    rustup toolchain install nightly && \
+    rustup target add wasm32-unknown-unknown --toolchain nightly && \
+    rustup default stable
+
+
+WORKDIR /usr/src/polkadot
+
+RUN cargo build --release --bin polkadot --features disputes --verbose
+RUN cp -v /usr/src/polkadot/target/release/polkadot /usr/local/bin
+
+# check if executable works in this container
+RUN /usr/local/bin/polkadot --version
+
+#
+### Runtime
+#
+
+FROM debian:buster-slim as runtime
+RUN apt-get update && \
+    apt-get install -y curl tini
+
+COPY --from=builder /usr/src/polkadot/target/release/polkadot /usr/local/bin
+# Non-root user for security purposes.
+#
+# UIDs below 10,000 are a security risk, as a container breakout could result
+# in the container being ran as a more privileged user on the host kernel with
+# the same UID.
+#
+# Static GID/UID is also useful for chown'ing files outside the container where
+# such a user does not exist.
+RUN groupadd --gid 10001 nonroot && \
+    useradd  --home-dir /home/nonroot \
+            --create-home \
+            --shell /bin/bash \
+            --gid nonroot \
+            --groups nonroot \
+            --uid 10000 nonroot
+WORKDIR /home/nonroot/polkadot
+
+RUN chown -R nonroot. /home/nonroot
+
+# Use the non-root user to run our application
+USER nonroot
+# check if executable works in this container
+RUN /usr/local/bin/polkadot --version
+# Tini allows us to avoid several Docker edge cases, see https://github.com/krallin/tini.
+ENTRYPOINT ["tini", "--", "/usr/local/bin/polkadot"]

pezkuwi/node/malus/integrationtests/0001-dispute-valid-block.toml

@@ -0,0 +1,42 @@
+[settings]
+timeout = 1000
+
+[relaychain.genesis.runtimeGenesis.patch.configuration.config.scheduler_params]
+max_validators_per_core = 1
+
+[relaychain]
+default_image = "{{ZOMBIENET_INTEGRATION_TEST_IMAGE}}"
+chain = "zagros-local"
+command = "pezkuwi"
+
+[[relaychain.nodes]]
+name = "alice"
+validator = true
+extra_args = ["--alice", "-lteyrchain=debug"]
+
+[[relaychain.nodes]]
+name = "bob"
+validator = true
+extra_args = ["--bob", "-lteyrchain=debug"]
+
+[[relaychain.nodes]]
+name = "charlie"
+validator = true
+extra_args = ["--charlie", "-lteyrchain=debug"]
+
+[[relaychain.nodes]]
+name = "dave"
+validator = true
+command = "malus dispute-ancestor"
+extra_args = ["--dave", "-lteyrchain=debug"]
+image = "{{MALUS_IMAGE}}"
+autoConnectApi = false
+
+[[teyrchains]]
+id = 100
+
+[teyrchains.collator]
+name = "collator01"
+image = "{{COL_IMAGE}}"
+command = "adder-collator"
+args = ["-lteyrchain=debug"]

pezkuwi/node/malus/integrationtests/0001-dispute-valid-block.zndsl

@@ -0,0 +1,29 @@
+Description: Disputes
+Network: ./0001-dispute-valid-block.toml
+Creds: config
+
+
+alice: is up
+bob: is up
+charlie: is up
+dave: is up
+alice: reports node_roles is 4
+bob: reports node_roles is 4
+alice: reports sub_libp2p_is_major_syncing is 0
+alice: reports block height is at least 2 within 15 seconds
+alice: reports peers count is at least 2
+bob: reports block height is at least 2
+bob: reports peers count is at least 2
+charlie: reports block height is at least 2
+charlie: reports peers count is at least 2
+alice: reports polkadot_teyrchain_candidate_disputes_total is at least 1 within 250 seconds
+bob: reports polkadot_teyrchain_candidate_disputes_total is at least 1 within 90 seconds
+charlie: reports polkadot_teyrchain_candidate_disputes_total is at least 1 within 90 seconds
+alice: reports polkadot_teyrchain_candidate_dispute_votes{validity="valid"} is at least 1 within 90 seconds
+bob: reports polkadot_teyrchain_candidate_dispute_votes{validity="valid"} is at least 2 within 90 seconds
+charlie: reports polkadot_teyrchain_candidate_dispute_votes{validity="valid"} is at least 2 within 90 seconds
+alice: reports polkadot_teyrchain_candidate_dispute_concluded{validity="valid"} is at least 1 within 90 seconds
+alice: reports polkadot_teyrchain_candidate_dispute_concluded{validity="invalid"} is 0 within 90 seconds
+bob: reports polkadot_teyrchain_candidate_dispute_concluded{validity="valid"} is at least 1 within 90 seconds
+charlie: reports polkadot_teyrchain_candidate_dispute_concluded{validity="valid"} is at least 1 within 90 seconds
+charlie: reports polkadot_teyrchain_candidate_dispute_concluded{validity="valid"} is at least 1 within 90 seconds

pezkuwi/node/malus/src/interceptor.rs

@@ -0,0 +1,333 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+//! A small set of wrapping types to cover most of our adversary test cases.
+//!
+//! This allows types with internal mutability to synchronize across
+//! multiple subsystems and intercept or replace incoming and outgoing
+//! messages on the overseer level.
+
+use pezkuwi_node_subsystem::*;
+pub use pezkuwi_node_subsystem::{messages::*, overseer, FromOrchestra};
+use std::{collections::VecDeque, future::Future, pin::Pin};
+
+/// Filter incoming and outgoing messages.
+pub trait MessageInterceptor<Sender>: Send + Sync + Clone + 'static
+where
+	Sender: overseer::SubsystemSender<<Self::Message as overseer::AssociateOutgoing>::OutgoingMessages>
+		+ Clone
+		+ 'static,
+{
+	/// The message type the original subsystem handles incoming.
+	type Message: overseer::AssociateOutgoing + Send + 'static;
+
+	/// Filter messages that are to be received by
+	/// the subsystem.
+	///
+	/// For non-trivial cases, the `sender` can be used to send
+	/// multiple messages after doing some additional processing.
+	fn intercept_incoming(
+		&self,
+		_sender: &mut Sender,
+		msg: FromOrchestra<Self::Message>,
+	) -> Option<FromOrchestra<Self::Message>> {
+		Some(msg)
+	}
+
+	/// Specifies if we need to replace some outgoing message with another (potentially empty)
+	/// message
+	fn need_intercept_outgoing(
+		&self,
+		_msg: &<Self::Message as overseer::AssociateOutgoing>::OutgoingMessages,
+	) -> bool {
+		false
+	}
+	/// Send modified message instead of the original one
+	fn intercept_outgoing(
+		&self,
+		_msg: &<Self::Message as overseer::AssociateOutgoing>::OutgoingMessages,
+	) -> Option<<Self::Message as overseer::AssociateOutgoing>::OutgoingMessages> {
+		None
+	}
+}
+
+/// A sender with the outgoing messages filtered.
+#[derive(Clone)]
+pub struct InterceptedSender<Sender, Fil> {
+	inner: Sender,
+	message_filter: Fil,
+}
+
+#[async_trait::async_trait]
+impl<OutgoingMessage, Sender, Fil> overseer::SubsystemSender<OutgoingMessage> for InterceptedSender<Sender, Fil>
+where
+	OutgoingMessage: overseer::AssociateOutgoing + Send + 'static + TryFrom<overseer::AllMessages>,
+	Sender: overseer::SubsystemSender<OutgoingMessage>
+		+ overseer::SubsystemSender<
+				<
+					<Fil as MessageInterceptor<Sender>>::Message as overseer::AssociateOutgoing
+				>::OutgoingMessages
+			>,
+	Fil: MessageInterceptor<Sender>,
+	<Fil as MessageInterceptor<Sender>>::Message: overseer::AssociateOutgoing,
+	<
+		<Fil as MessageInterceptor<Sender>>::Message as overseer::AssociateOutgoing
+	>::OutgoingMessages:
+		From<OutgoingMessage> + Send + Sync,
+	<OutgoingMessage as TryFrom<overseer::AllMessages>>::Error: std::fmt::Debug,
+{
+	async fn send_message(&mut self, msg: OutgoingMessage) {
+		self.send_message_with_priority::<overseer::NormalPriority>(msg).await;
+	}
+
+	async fn send_message_with_priority<P: Priority>(&mut self, msg: OutgoingMessage) {
+		let msg = <
+					<<Fil as MessageInterceptor<Sender>>::Message as overseer::AssociateOutgoing
+				>::OutgoingMessages as From<OutgoingMessage>>::from(msg);
+		if self.message_filter.need_intercept_outgoing(&msg) {
+			if let Some(msg) = self.message_filter.intercept_outgoing(&msg) {
+				self.inner.send_message(msg).await;
+			}
+		}
+		else {
+			self.inner.send_message(msg).await;
+		}
+	}
+
+	fn try_send_message(
+		&mut self,
+		msg: OutgoingMessage,
+	) -> Result<(), pezkuwi_node_subsystem_util::metered::TrySendError<OutgoingMessage>> {
+		self.try_send_message_with_priority::<overseer::NormalPriority>(msg)
+	}
+
+	fn try_send_message_with_priority<P: Priority>(&mut self, msg: OutgoingMessage) -> Result<(), TrySendError<OutgoingMessage>> {
+		let msg = <
+				<<Fil as MessageInterceptor<Sender>>::Message as overseer::AssociateOutgoing
+			>::OutgoingMessages as From<OutgoingMessage>>::from(msg);
+		if self.message_filter.need_intercept_outgoing(&msg) {
+			if let Some(real_msg) = self.message_filter.intercept_outgoing(&msg) {
+				let orig_msg : OutgoingMessage = msg.into().try_into().expect("must be able to recover the original message");
+				self.inner.try_send_message(real_msg).map_err(|e| {
+					match e {
+						TrySendError::Full(_) => TrySendError::Full(orig_msg),
+						TrySendError::Closed(_) => TrySendError::Closed(orig_msg),
+					}
+				})
+			}
+			else {
+				// No message to send after intercepting
+				Ok(())
+			}
+		}
+		else {
+			let orig_msg : OutgoingMessage = msg.into().try_into().expect("must be able to recover the original message");
+			self.inner.try_send_message(orig_msg)
+		}
+	}
+
+	async fn send_messages<T>(&mut self, msgs: T)
+	where
+		T: IntoIterator<Item = OutgoingMessage> + Send,
+		T::IntoIter: Send,
+	{
+		for msg in msgs {
+			self.send_message(msg).await;
+		}
+	}
+
+	fn send_unbounded_message(&mut self, msg: OutgoingMessage) {
+		let msg = <
+				<<Fil as MessageInterceptor<Sender>>::Message as overseer::AssociateOutgoing
+			>::OutgoingMessages as From<OutgoingMessage>>::from(msg);
+		if self.message_filter.need_intercept_outgoing(&msg) {
+			if let Some(msg) = self.message_filter.intercept_outgoing(&msg) {
+				self.inner.send_unbounded_message(msg);
+			}
+		}
+		else {
+			self.inner.send_unbounded_message(msg);
+		}
+	}
+}
+
+/// A subsystem context, that filters the outgoing messages.
+pub struct InterceptedContext<Context, Fil>
+where
+	Context: overseer::SubsystemContext<Error=SubsystemError, Signal=OverseerSignal>,
+	Fil: MessageInterceptor<<Context as overseer::SubsystemContext>::Sender>,
+	<Context as overseer::SubsystemContext>::Sender:
+		overseer::SubsystemSender<
+			<
+				<
+					Fil as MessageInterceptor<<Context as overseer::SubsystemContext>::Sender>
+				>::Message as overseer::AssociateOutgoing
+			>::OutgoingMessages,
+		>,
+{
+	inner: Context,
+	message_filter: Fil,
+	sender: InterceptedSender<<Context as overseer::SubsystemContext>::Sender, Fil>,
+	message_buffer: VecDeque<FromOrchestra<<Context as overseer::SubsystemContext>::Message>>,
+}
+
+impl<Context, Fil> InterceptedContext<Context, Fil>
+where
+	Context: overseer::SubsystemContext<Error=SubsystemError,Signal=OverseerSignal>,
+	Fil: MessageInterceptor<
+		<Context as overseer::SubsystemContext>::Sender,
+		Message = <Context as overseer::SubsystemContext>::Message,
+	>,
+	<Context as overseer::SubsystemContext>::Message: overseer::AssociateOutgoing,
+	<Context as overseer::SubsystemContext>::Sender: overseer::SubsystemSender<
+		<<Context as overseer::SubsystemContext>::Message as overseer::AssociateOutgoing>::OutgoingMessages
+	>
+{
+	pub fn new(mut inner: Context, message_filter: Fil) -> Self {
+		let sender = InterceptedSender::<<Context as overseer::SubsystemContext>::Sender, Fil> {
+			inner: inner.sender().clone(),
+			message_filter: message_filter.clone(),
+		};
+		Self { inner, message_filter, sender, message_buffer: VecDeque::new() }
+	}
+}
+
+#[async_trait::async_trait]
+impl<Context, Fil> overseer::SubsystemContext for InterceptedContext<Context, Fil>
+where
+	Context: overseer::SubsystemContext<Error=SubsystemError,Signal=OverseerSignal>,
+	<Context as overseer::SubsystemContext>::Message:
+		overseer::AssociateOutgoing,
+	<Context as overseer::SubsystemContext>::Sender:
+		overseer::SubsystemSender<
+			<<Context as overseer::SubsystemContext>::Message as overseer::AssociateOutgoing>::OutgoingMessages
+		>,
+	InterceptedSender<<Context as overseer::SubsystemContext>::Sender, Fil>:
+		overseer::SubsystemSender<
+			<<Context as overseer::SubsystemContext>::Message as overseer::AssociateOutgoing>::OutgoingMessages
+		>,
+	Fil: MessageInterceptor<
+		<Context as overseer::SubsystemContext>::Sender,
+		Message = <Context as overseer::SubsystemContext>::Message,
+	>,
+{
+	type Message = <Context as overseer::SubsystemContext>::Message;
+	type Sender = InterceptedSender<<Context as overseer::SubsystemContext>::Sender, Fil>;
+	type Error = SubsystemError;
+	type OutgoingMessages = <<Context as overseer::SubsystemContext>::Message as overseer::AssociateOutgoing>::OutgoingMessages;
+	type Signal = OverseerSignal;
+
+	async fn try_recv(&mut self) -> Result<Option<FromOrchestra<Self::Message>>, ()> {
+		loop {
+			match self.inner.try_recv().await? {
+				None => return Ok(None),
+				Some(msg) =>
+					if let Some(msg) =
+						self.message_filter.intercept_incoming(self.inner.sender(), msg)
+					{
+						return Ok(Some(msg))
+					},
+			}
+		}
+	}
+
+	async fn recv(&mut self) -> SubsystemResult<FromOrchestra<Self::Message>> {
+		if let Some(msg) = self.message_buffer.pop_front() {
+			return Ok(msg)
+		}
+		loop {
+			let msg = self.inner.recv().await?;
+			if let Some(msg) = self.message_filter.intercept_incoming(self.inner.sender(), msg) {
+				return Ok(msg)
+			}
+		}
+	}
+
+	async fn recv_signal(&mut self) -> SubsystemResult<Self::Signal> {
+		loop {
+			let msg = self.inner.recv().await?;
+			if let Some(msg) = self.message_filter.intercept_incoming(self.inner.sender(), msg) {
+				if let FromOrchestra::Signal(sig) = msg {
+					return Ok(sig)
+				} else {
+					self.message_buffer.push_back(msg)
+				}
+			}
+		}
+	}
+
+	fn spawn(
+		&mut self,
+		name: &'static str,
+		s: Pin<Box<dyn Future<Output = ()> + Send>>,
+	) -> SubsystemResult<()> {
+		self.inner.spawn(name, s)
+	}
+
+	fn spawn_blocking(
+		&mut self,
+		name: &'static str,
+		s: Pin<Box<dyn Future<Output = ()> + Send>>,
+	) -> SubsystemResult<()> {
+		self.inner.spawn_blocking(name, s)
+	}
+
+	fn sender(&mut self) -> &mut Self::Sender {
+		&mut self.sender
+	}
+}
+
+/// A subsystem to which incoming and outgoing filters are applied.
+pub struct InterceptedSubsystem<Sub, Interceptor> {
+	pub subsystem: Sub,
+	pub message_interceptor: Interceptor,
+}
+
+impl<Sub, Interceptor> InterceptedSubsystem<Sub, Interceptor> {
+	pub fn new(subsystem: Sub, message_interceptor: Interceptor) -> Self {
+		Self { subsystem, message_interceptor }
+	}
+}
+
+impl<Context, Sub, Interceptor> overseer::Subsystem<Context, SubsystemError> for InterceptedSubsystem<Sub, Interceptor>
+where
+	Context:
+		overseer::SubsystemContext<Error=SubsystemError,Signal=OverseerSignal> + Sync + Send,
+	InterceptedContext<Context, Interceptor>:
+		overseer::SubsystemContext<Error=SubsystemError,Signal=OverseerSignal>,
+	Sub:
+		overseer::Subsystem<InterceptedContext<Context, Interceptor>, SubsystemError>,
+	Interceptor:
+		MessageInterceptor<
+			<Context as overseer::SubsystemContext>::Sender,
+			Message = <Context as overseer::SubsystemContext>::Message,
+		>,
+	<Context as overseer::SubsystemContext>::Message:
+		overseer::AssociateOutgoing,
+	<Context as overseer::SubsystemContext>::Sender:
+		overseer::SubsystemSender<
+				<<Context as overseer::SubsystemContext>::Message as overseer::AssociateOutgoing
+			>::OutgoingMessages
+		>,
+{
+	fn start(self, ctx: Context) -> SpawnedSubsystem {
+		let ctx = InterceptedContext::new(ctx, self.message_interceptor);
+		overseer::Subsystem::<InterceptedContext<Context, Interceptor>, SubsystemError>::start(
+			self.subsystem,
+			ctx,
+		)
+	}
+}

pezkuwi/node/malus/src/malus.rs

@@ -0,0 +1,243 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+//! A malus or nemesis node launch code.
+
+use clap::Parser;
+use color_eyre::eyre;
+
+pub(crate) mod interceptor;
+pub(crate) mod shared;
+
+mod variants;
+
+use variants::*;
+
+/// Define the different variants of behavior.
+#[derive(Debug, Parser)]
+#[command(about = "Malus - the nemesis of pezkuwi.", version, rename_all = "kebab-case")]
+enum NemesisVariant {
+	/// Suggest a candidate with an invalid proof of validity.
+	SuggestGarbageCandidate(SuggestGarbageCandidateOptions),
+	/// Support disabled validators in backing and statement distribution.
+	SupportDisabled(SupportDisabledOptions),
+	/// Back a candidate with a specifically crafted proof of validity.
+	BackGarbageCandidate(BackGarbageCandidateOptions),
+	/// Delayed disputing of ancestors that are perfectly fine.
+	DisputeAncestor(DisputeAncestorOptions),
+	/// Delayed disputing of finalized candidates.
+	DisputeFinalizedCandidates(DisputeFinalizedCandidatesOptions),
+	/// Spam many request statements instead of sending a single one.
+	SpamStatementRequests(SpamStatementRequestsOptions),
+}
+
+#[derive(Debug, Parser)]
+#[allow(missing_docs)]
+struct MalusCli {
+	#[command(subcommand)]
+	pub variant: NemesisVariant,
+	/// Sets the minimum delay between the best and finalized block.
+	pub finality_delay: Option<u32>,
+}
+
+impl MalusCli {
+	/// Launch a malus node.
+	fn launch(self) -> eyre::Result<()> {
+		let finality_delay = self.finality_delay;
+		match self.variant {
+			NemesisVariant::BackGarbageCandidate(opts) => {
+				let BackGarbageCandidateOptions { percentage, cli } = opts;
+
+				pezkuwi_cli::run_node(cli, BackGarbageCandidates { percentage }, finality_delay)?
+			},
+			NemesisVariant::SuggestGarbageCandidate(opts) => {
+				let SuggestGarbageCandidateOptions { percentage, cli } = opts;
+
+				pezkuwi_cli::run_node(cli, SuggestGarbageCandidates { percentage }, finality_delay)?
+			},
+			NemesisVariant::SupportDisabled(opts) => {
+				let SupportDisabledOptions { cli } = opts;
+
+				pezkuwi_cli::run_node(cli, SupportDisabled, finality_delay)?
+			},
+			NemesisVariant::DisputeAncestor(opts) => {
+				let DisputeAncestorOptions {
+					fake_validation,
+					fake_validation_error,
+					percentage,
+					cli,
+				} = opts;
+
+				pezkuwi_cli::run_node(
+					cli,
+					DisputeValidCandidates { fake_validation, fake_validation_error, percentage },
+					finality_delay,
+				)?
+			},
+			NemesisVariant::DisputeFinalizedCandidates(opts) => {
+				let DisputeFinalizedCandidatesOptions { dispute_offset, cli } = opts;
+
+				pezkuwi_cli::run_node(
+					cli,
+					DisputeFinalizedCandidates { dispute_offset },
+					finality_delay,
+				)?
+			},
+			NemesisVariant::SpamStatementRequests(opts) => {
+				let SpamStatementRequestsOptions { spam_factor, cli } = opts;
+
+				pezkuwi_cli::run_node(cli, SpamStatementRequests { spam_factor }, finality_delay)?
+			},
+		}
+		Ok(())
+	}
+}
+
+fn main() -> eyre::Result<()> {
+	color_eyre::install()?;
+	let cli = MalusCli::parse();
+	cli.launch()?;
+	Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	#[test]
+	fn subcommand_works() {
+		let cli = MalusCli::try_parse_from(IntoIterator::into_iter([
+			"malus",
+			"dispute-ancestor",
+			"--bob",
+		]))
+		.unwrap();
+		assert_matches::assert_matches!(cli, MalusCli {
+			variant: NemesisVariant::DisputeAncestor(run),
+			..
+		} => {
+			assert!(run.cli.run.base.bob);
+		});
+	}
+
+	#[test]
+	fn percentage_works_suggest_garbage() {
+		let cli = MalusCli::try_parse_from(IntoIterator::into_iter([
+			"malus",
+			"suggest-garbage-candidate",
+			"--percentage",
+			"100",
+			"--bob",
+		]))
+		.unwrap();
+		assert_matches::assert_matches!(cli, MalusCli {
+			variant: NemesisVariant::SuggestGarbageCandidate(run),
+			..
+		} => {
+			assert!(run.cli.run.base.bob);
+		});
+	}
+
+	#[test]
+	fn percentage_works_dispute_ancestor() {
+		let cli = MalusCli::try_parse_from(IntoIterator::into_iter([
+			"malus",
+			"dispute-ancestor",
+			"--percentage",
+			"100",
+			"--bob",
+		]))
+		.unwrap();
+		assert_matches::assert_matches!(cli, MalusCli {
+			variant: NemesisVariant::DisputeAncestor(run),
+			..
+		} => {
+			assert!(run.cli.run.base.bob);
+		});
+	}
+
+	#[test]
+	fn percentage_works_back_garbage() {
+		let cli = MalusCli::try_parse_from(IntoIterator::into_iter([
+			"malus",
+			"back-garbage-candidate",
+			"--percentage",
+			"100",
+			"--bob",
+		]))
+		.unwrap();
+		assert_matches::assert_matches!(cli, MalusCli {
+			variant: NemesisVariant::BackGarbageCandidate(run),
+			..
+		} => {
+			assert!(run.cli.run.base.bob);
+		});
+	}
+
+	#[test]
+	#[should_panic]
+	fn validate_range_for_percentage() {
+		let cli = MalusCli::try_parse_from(IntoIterator::into_iter([
+			"malus",
+			"suggest-garbage-candidate",
+			"--percentage",
+			"101",
+			"--bob",
+		]))
+		.unwrap();
+		assert_matches::assert_matches!(cli, MalusCli {
+			variant: NemesisVariant::DisputeAncestor(run),
+			..
+		} => {
+			assert!(run.cli.run.base.bob);
+		});
+	}
+
+	#[test]
+	fn dispute_finalized_candidates_works() {
+		let cli = MalusCli::try_parse_from(IntoIterator::into_iter([
+			"malus",
+			"dispute-finalized-candidates",
+			"--bob",
+		]))
+		.unwrap();
+		assert_matches::assert_matches!(cli, MalusCli {
+			variant: NemesisVariant::DisputeFinalizedCandidates(run),
+			..
+		} => {
+			assert!(run.cli.run.base.bob);
+		});
+	}
+
+	#[test]
+	fn dispute_finalized_offset_value_works() {
+		let cli = MalusCli::try_parse_from(IntoIterator::into_iter([
+			"malus",
+			"dispute-finalized-candidates",
+			"--dispute-offset",
+			"13",
+			"--bob",
+		]))
+		.unwrap();
+		assert_matches::assert_matches!(cli, MalusCli {
+			variant: NemesisVariant::DisputeFinalizedCandidates(opts),
+			..
+		} => {
+			assert_eq!(opts.dispute_offset, 13); // This line checks that dispute_offset is correctly set to 13
+			assert!(opts.cli.run.base.bob);
+		});
+	}
+}

pezkuwi/node/malus/src/shared.rs

@@ -0,0 +1,49 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+use futures::prelude::*;
+use sp_core::traits::SpawnNamed;
+
+pub const MALUS: &str = "MALUS";
+
+#[allow(unused)]
+pub(crate) const MALICIOUS_POV: &[u8] = "😈😈pov_looks_valid_to_me😈😈".as_bytes();
+
+/// Launch a service task for each item in the provided queue.
+#[allow(unused)]
+pub(crate) fn launch_processing_task<X, F, U, Q, S>(spawner: &S, queue: Q, action: F)
+where
+	F: Fn(X) -> U + Send + 'static,
+	U: Future<Output = ()> + Send + 'static,
+	Q: Stream<Item = X> + Send + 'static,
+	X: Send,
+	S: 'static + SpawnNamed + Clone + Unpin,
+{
+	let spawner2: S = spawner.clone();
+	spawner.spawn(
+		"nemesis-queue-processor",
+		Some("malus"),
+		Box::pin(async move {
+			let spawner3 = spawner2.clone();
+			queue
+				.for_each(move |input| {
+					spawner3.spawn("nemesis-task", Some("malus"), Box::pin(action(input)));
+					async move { () }
+				})
+				.await;
+		}),
+	);
+}

pezkuwi/node/malus/src/tests.rs

@@ -0,0 +1,140 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+use super::*;
+
+use pezkuwi_node_subsystem_test_helpers::*;
+
+use pezkuwi_node_subsystem::{
+	messages::AvailabilityStoreMessage,
+	overseer::{dummy::DummySubsystem, gen::TimeoutExt, Subsystem, AssociateOutgoing},
+	SubsystemError,
+};
+
+#[derive(Clone, Debug)]
+struct BlackHoleInterceptor;
+
+impl<Sender> MessageInterceptor<Sender> for BlackHoleInterceptor
+where
+	Sender: overseer::AvailabilityStoreSenderTrait
+		+ Clone
+		+ 'static,
+{
+	type Message = AvailabilityStoreMessage;
+	fn intercept_incoming(
+		&self,
+		_sender: &mut Sender,
+		msg: FromOrchestra<Self::Message>,
+	) -> Option<FromOrchestra<Self::Message>> {
+		match msg {
+			FromOrchestra::Communication { msg: _msg } => None,
+			// to conclude the test cleanly
+			sig => Some(sig),
+		}
+	}
+}
+
+#[derive(Clone, Debug)]
+struct PassInterceptor;
+
+impl<Sender> MessageInterceptor<Sender> for PassInterceptor
+where
+	Sender: overseer::AvailabilityStoreSenderTrait
+		+ Clone
+		+ 'static,
+{
+	type Message = AvailabilityStoreMessage;
+}
+
+async fn overseer_send<T: Into<AllMessages>>(overseer: &mut TestSubsystemContextHandle<T>, msg: T) {
+	overseer.send(FromOrchestra::Communication { msg }).await;
+}
+
+use sp_core::testing::TaskExecutor;
+
+fn launch_harness<F, M, Sub, G>(test_gen: G)
+where
+	F: Future<Output = TestSubsystemContextHandle<M>> + Send,
+	M: AssociateOutgoing + std::fmt::Debug + Send + 'static,
+	// <M as AssociateOutgoing>::OutgoingMessages: From<M>,
+	Sub: Subsystem<TestSubsystemContext<M, SpawnGlue<TaskExecutor>>, SubsystemError>,
+	G: Fn(TestSubsystemContextHandle<M>) -> (F, Sub),
+{
+	let pool = TaskExecutor::new();
+	let (context, overseer) = make_subsystem_context(pool);
+
+	let (test_fut, subsystem) = test_gen(overseer);
+	let subsystem = async move {
+		subsystem.start(context).future.await.unwrap();
+	};
+	futures::pin_mut!(test_fut);
+	futures::pin_mut!(subsystem);
+
+	futures::executor::block_on(futures::future::join(
+		async move {
+			let mut overseer = test_fut.await;
+			overseer.send(FromOrchestra::Signal(OverseerSignal::Conclude)).await;
+		},
+		subsystem,
+	))
+	.1;
+}
+
+#[test]
+fn integrity_test_intercept() {
+	launch_harness(|mut overseer| {
+		let sub = DummySubsystem;
+
+		let sub_intercepted = InterceptedSubsystem::new(sub, BlackHoleInterceptor);
+
+		(
+			async move {
+				let (tx, rx) = futures::channel::oneshot::channel();
+				overseer_send(
+					&mut overseer,
+					AvailabilityStoreMessage::QueryChunk(Default::default(), 0.into(), tx),
+				)
+				.await;
+				let _ = rx.timeout(std::time::Duration::from_millis(100)).await.unwrap();
+				overseer
+			},
+			sub_intercepted,
+		)
+	})
+}
+
+#[test]
+fn integrity_test_pass() {
+	launch_harness(|mut overseer| {
+		let sub = DummySubsystem;
+
+		let sub_intercepted = InterceptedSubsystem::new(sub, PassInterceptor);
+
+		(
+			async move {
+				let (tx, rx) = futures::channel::oneshot::channel();
+				overseer_send(
+					&mut overseer,
+					AvailabilityStoreMessage::QueryChunk(Default::default(), 0.into(), tx),
+				)
+				.await;
+				let _ = rx.timeout(std::time::Duration::from_millis(100)).await.unwrap();
+				overseer
+			},
+			sub_intercepted,
+		)
+	})
+}

pezkuwi/node/malus/src/variants/back_garbage_candidate.rs

@@ -0,0 +1,86 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+//! This variant of Malus backs/approves all malicious candidates crafted by
+//! `suggest-garbage-candidate` variant and behaves honestly with other
+//! candidates.
+
+use pezkuwi_cli::{
+	service::{
+		AuxStore, Error, ExtendedOverseerGenArgs, Overseer, OverseerConnector, OverseerGen,
+		OverseerGenArgs, OverseerHandle,
+	},
+	validator_overseer_builder, Cli,
+};
+use pezkuwi_node_subsystem::SpawnGlue;
+use pezkuwi_node_subsystem_types::{ChainApiBackend, RuntimeApiSubsystemClient};
+use sp_core::traits::SpawnNamed;
+
+use crate::{
+	interceptor::*,
+	variants::{FakeCandidateValidation, FakeCandidateValidationError, ReplaceValidationResult},
+};
+
+use std::sync::Arc;
+
+#[derive(Debug, clap::Parser)]
+#[clap(rename_all = "kebab-case")]
+#[allow(missing_docs)]
+pub struct BackGarbageCandidateOptions {
+	/// Determines the percentage of garbage candidates that should be backed.
+	/// Defaults to 100% of garbage candidates being backed.
+	#[clap(short, long, ignore_case = true, default_value_t = 100, value_parser = clap::value_parser!(u8).range(0..=100))]
+	pub percentage: u8,
+
+	#[clap(flatten)]
+	pub cli: Cli,
+}
+
+/// Generates an overseer that replaces the candidate validation subsystem with our malicious
+/// variant.
+pub(crate) struct BackGarbageCandidates {
+	/// The probability of behaving maliciously.
+	pub percentage: u8,
+}
+
+impl OverseerGen for BackGarbageCandidates {
+	fn generate<Spawner, RuntimeClient>(
+		&self,
+		connector: OverseerConnector,
+		args: OverseerGenArgs<'_, Spawner, RuntimeClient>,
+		ext_args: Option<ExtendedOverseerGenArgs>,
+	) -> Result<(Overseer<SpawnGlue<Spawner>, Arc<RuntimeClient>>, OverseerHandle), Error>
+	where
+		RuntimeClient: RuntimeApiSubsystemClient + ChainApiBackend + AuxStore + 'static,
+		Spawner: 'static + SpawnNamed + Clone + Unpin,
+	{
+		let validation_filter = ReplaceValidationResult::new(
+			FakeCandidateValidation::BackingAndApprovalValid,
+			FakeCandidateValidationError::InvalidOutputs,
+			f64::from(self.percentage),
+		);
+
+		validator_overseer_builder(
+			args,
+			ext_args.expect("Extended arguments required to build validator overseer are provided"),
+		)?
+		.replace_candidate_validation(move |cv_subsystem| {
+			InterceptedSubsystem::new(cv_subsystem, validation_filter)
+		})
+		.build_with_connector(connector)
+		.map_err(|e| e.into())
+	}
+}

pezkuwi/node/malus/src/variants/common.rs

@@ -0,0 +1,356 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Implements common code for nemesis. Currently, only `ReplaceValidationResult`
+//! interceptor is implemented.
+use crate::{
+	interceptor::*,
+	shared::{MALICIOUS_POV, MALUS},
+};
+
+use pezkuwi_node_primitives::{InvalidCandidate, ValidationResult};
+
+use pezkuwi_primitives::{
+	CandidateCommitments, CandidateDescriptorV2 as CandidateDescriptor,
+	CandidateReceiptV2 as CandidateReceipt, PersistedValidationData, PvfExecKind,
+};
+
+use futures::channel::oneshot;
+use rand::distributions::{Bernoulli, Distribution};
+
+#[derive(clap::ValueEnum, Clone, Copy, Debug, PartialEq)]
+#[value(rename_all = "kebab-case")]
+#[non_exhaustive]
+pub enum FakeCandidateValidation {
+	Disabled,
+	BackingInvalid,
+	ApprovalInvalid,
+	BackingAndApprovalInvalid,
+	BackingValid,
+	ApprovalValid,
+	BackingAndApprovalValid,
+}
+
+impl FakeCandidateValidation {
+	fn misbehaves_valid(&self) -> bool {
+		use FakeCandidateValidation::*;
+
+		match *self {
+			BackingValid | ApprovalValid | BackingAndApprovalValid => true,
+			_ => false,
+		}
+	}
+
+	fn misbehaves_invalid(&self) -> bool {
+		use FakeCandidateValidation::*;
+
+		match *self {
+			BackingInvalid | ApprovalInvalid | BackingAndApprovalInvalid => true,
+			_ => false,
+		}
+	}
+
+	fn includes_backing(&self) -> bool {
+		use FakeCandidateValidation::*;
+
+		match *self {
+			BackingInvalid | BackingAndApprovalInvalid | BackingValid | BackingAndApprovalValid =>
+				true,
+			_ => false,
+		}
+	}
+
+	fn includes_approval(&self) -> bool {
+		use FakeCandidateValidation::*;
+
+		match *self {
+			ApprovalInvalid |
+			BackingAndApprovalInvalid |
+			ApprovalValid |
+			BackingAndApprovalValid => true,
+			_ => false,
+		}
+	}
+
+	fn should_misbehave(&self, timeout: PvfExecKind) -> bool {
+		match timeout {
+			PvfExecKind::Backing => self.includes_backing(),
+			PvfExecKind::Approval => self.includes_approval(),
+		}
+	}
+}
+
+/// Candidate invalidity details
+#[derive(clap::ValueEnum, Clone, Copy, Debug, PartialEq)]
+#[value(rename_all = "kebab-case")]
+pub enum FakeCandidateValidationError {
+	/// Validation outputs check doesn't pass.
+	InvalidOutputs,
+	/// Failed to execute.`validate_block`. This includes function panicking.
+	ExecutionError,
+	/// Execution timeout.
+	Timeout,
+	/// Validation input is over the limit.
+	ParamsTooLarge,
+	/// Code size is over the limit.
+	CodeTooLarge,
+	/// PoV does not decompress correctly.
+	POVDecompressionFailure,
+	/// Validation function returned invalid data.
+	BadReturn,
+	/// Invalid relay chain parent.
+	BadParent,
+	/// POV hash does not match.
+	POVHashMismatch,
+	/// Bad collator signature.
+	BadSignature,
+	/// Para head hash does not match.
+	ParaHeadHashMismatch,
+	/// Validation code hash does not match.
+	CodeHashMismatch,
+}
+
+impl Into<InvalidCandidate> for FakeCandidateValidationError {
+	fn into(self) -> InvalidCandidate {
+		match self {
+			FakeCandidateValidationError::ExecutionError =>
+				InvalidCandidate::ExecutionError("Malus".into()),
+			FakeCandidateValidationError::InvalidOutputs => InvalidCandidate::InvalidOutputs,
+			FakeCandidateValidationError::Timeout => InvalidCandidate::Timeout,
+			FakeCandidateValidationError::ParamsTooLarge => InvalidCandidate::ParamsTooLarge(666),
+			FakeCandidateValidationError::CodeTooLarge => InvalidCandidate::CodeTooLarge(666),
+			FakeCandidateValidationError::POVDecompressionFailure =>
+				InvalidCandidate::PoVDecompressionFailure,
+			FakeCandidateValidationError::BadReturn => InvalidCandidate::BadReturn,
+			FakeCandidateValidationError::BadParent => InvalidCandidate::BadParent,
+			FakeCandidateValidationError::POVHashMismatch => InvalidCandidate::PoVHashMismatch,
+			FakeCandidateValidationError::BadSignature => InvalidCandidate::BadSignature,
+			FakeCandidateValidationError::ParaHeadHashMismatch =>
+				InvalidCandidate::ParaHeadHashMismatch,
+			FakeCandidateValidationError::CodeHashMismatch => InvalidCandidate::CodeHashMismatch,
+		}
+	}
+}
+
+#[derive(Clone, Debug)]
+/// An interceptor which fakes validation result with a preconfigured result.
+/// Replaces `CandidateValidationSubsystem`.
+pub struct ReplaceValidationResult {
+	fake_validation: FakeCandidateValidation,
+	fake_validation_error: FakeCandidateValidationError,
+	distribution: Bernoulli,
+}
+
+impl ReplaceValidationResult {
+	pub fn new(
+		fake_validation: FakeCandidateValidation,
+		fake_validation_error: FakeCandidateValidationError,
+		percentage: f64,
+	) -> Self {
+		let distribution = Bernoulli::new(percentage / 100.0)
+			.expect("Invalid probability! Percentage must be in range [0..=100].");
+		Self { fake_validation, fake_validation_error, distribution }
+	}
+}
+
+pub fn create_fake_candidate_commitments(
+	persisted_validation_data: &PersistedValidationData,
+) -> CandidateCommitments {
+	// Backing rejects candidates which output the same head as the parent,
+	// therefore we must create a new head which is not equal to the parent.
+	let mut head_data = persisted_validation_data.parent_head.clone();
+	if head_data.0.is_empty() {
+		head_data.0.push(0);
+	} else {
+		head_data.0[0] = head_data.0[0].wrapping_add(1);
+	};
+
+	CandidateCommitments {
+		upward_messages: Default::default(),
+		horizontal_messages: Default::default(),
+		new_validation_code: None,
+		head_data,
+		processed_downward_messages: 0,
+		hrmp_watermark: persisted_validation_data.relay_parent_number,
+	}
+}
+
+// Create and send validation response. This function needs the persistent validation data.
+fn create_validation_response(
+	persisted_validation_data: PersistedValidationData,
+	descriptor: CandidateDescriptor,
+	response_sender: oneshot::Sender<Result<ValidationResult, ValidationFailed>>,
+) {
+	let commitments = create_fake_candidate_commitments(&persisted_validation_data);
+
+	// Craft the new malicious candidate.
+	let candidate_receipt = CandidateReceipt { descriptor, commitments_hash: commitments.hash() };
+
+	let result = Ok(ValidationResult::Valid(commitments, persisted_validation_data));
+
+	gum::debug!(
+		target: MALUS,
+		para_id = ?candidate_receipt.descriptor.para_id(),
+		candidate_hash = ?candidate_receipt.hash(),
+		"ValidationResult: {:?}",
+		&result
+	);
+
+	response_sender.send(result).unwrap();
+}
+
+impl<Sender> MessageInterceptor<Sender> for ReplaceValidationResult
+where
+	Sender: overseer::CandidateValidationSenderTrait + Clone + Send + 'static,
+{
+	type Message = CandidateValidationMessage;
+
+	// Capture all (approval and backing) candidate validation requests and depending on
+	// configuration fail them.
+	fn intercept_incoming(
+		&self,
+		_subsystem_sender: &mut Sender,
+		msg: FromOrchestra<Self::Message>,
+	) -> Option<FromOrchestra<Self::Message>> {
+		match msg {
+			// Message sent by the approval voting subsystem
+			FromOrchestra::Communication {
+				msg:
+					CandidateValidationMessage::ValidateFromExhaustive {
+						validation_data,
+						validation_code,
+						candidate_receipt,
+						pov,
+						executor_params,
+						exec_kind,
+						response_sender,
+						..
+					},
+			} => {
+				match self.fake_validation {
+					x if x.misbehaves_valid() && x.should_misbehave(exec_kind.into()) => {
+						// Behave normally if the `PoV` is not known to be malicious.
+						if pov.block_data.0.as_slice() != MALICIOUS_POV {
+							return Some(FromOrchestra::Communication {
+								msg: CandidateValidationMessage::ValidateFromExhaustive {
+									validation_data,
+									validation_code,
+									candidate_receipt,
+									pov,
+									executor_params,
+									exec_kind,
+									response_sender,
+								},
+							});
+						}
+						// Create the fake response with probability `p` if the `PoV` is malicious,
+						// where 'p' defaults to 100% for suggest-garbage-candidate variant.
+						let behave_maliciously = self.distribution.sample(&mut rand::thread_rng());
+						match behave_maliciously {
+							true => {
+								gum::info!(
+									target: MALUS,
+									?behave_maliciously,
+									"😈 Creating malicious ValidationResult::Valid message with fake candidate commitments.",
+								);
+
+								create_validation_response(
+									validation_data,
+									candidate_receipt.descriptor,
+									response_sender,
+								);
+								None
+							},
+							false => {
+								// Behave normally with probability `(1-p)` for a malicious `PoV`.
+								gum::info!(
+									target: MALUS,
+									?behave_maliciously,
+									"😈 Passing CandidateValidationMessage::ValidateFromExhaustive to the candidate validation subsystem.",
+								);
+
+								Some(FromOrchestra::Communication {
+									msg: CandidateValidationMessage::ValidateFromExhaustive {
+										validation_data,
+										validation_code,
+										candidate_receipt,
+										pov,
+										executor_params,
+										exec_kind,
+										response_sender,
+									},
+								})
+							},
+						}
+					},
+					x if x.misbehaves_invalid() && x.should_misbehave(exec_kind.into()) => {
+						// Set the validation result to invalid with probability `p` and trigger a
+						// dispute
+						let behave_maliciously = self.distribution.sample(&mut rand::thread_rng());
+						match behave_maliciously {
+							true => {
+								let validation_result =
+									ValidationResult::Invalid(self.fake_validation_error.into());
+
+								gum::info!(
+									target: MALUS,
+									?behave_maliciously,
+									para_id = ?candidate_receipt.descriptor.para_id(),
+									"😈 Maliciously sending invalid validation result: {:?}.",
+									&validation_result,
+								);
+
+								// We're not even checking the candidate, this makes us appear
+								// faster than honest validators.
+								response_sender.send(Ok(validation_result)).unwrap();
+								None
+							},
+							false => {
+								// Behave normally with probability `(1-p)`
+								gum::info!(target: MALUS, "😈 'Decided' to not act maliciously.",);
+
+								Some(FromOrchestra::Communication {
+									msg: CandidateValidationMessage::ValidateFromExhaustive {
+										validation_data,
+										validation_code,
+										candidate_receipt,
+										pov,
+										executor_params,
+										exec_kind,
+										response_sender,
+									},
+								})
+							},
+						}
+					},
+					// Handle FakeCandidateValidation::Disabled
+					_ => Some(FromOrchestra::Communication {
+						msg: CandidateValidationMessage::ValidateFromExhaustive {
+							validation_data,
+							validation_code,
+							candidate_receipt,
+							pov,
+							executor_params,
+							exec_kind,
+							response_sender,
+						},
+					}),
+				}
+			},
+			msg => Some(msg),
+		}
+	}
+}

pezkuwi/node/malus/src/variants/dispute_finalized_candidates.rs

@@ -0,0 +1,263 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+//! A malicious node variant that attempts to dispute finalized candidates.
+//!
+//! This malus variant behaves honestly in backing and approval voting.
+//! The maliciousness comes from emitting an extra dispute statement on top of the other ones.
+//!
+//! Some extra quirks which generally should be insignificant:
+//! - The malus node will not dispute at session boundaries
+//! - The malus node will not dispute blocks it backed itself
+//! - Be cautious about the size of the network to make sure disputes are not auto-confirmed
+//! (7 validators is the smallest network size as it needs [(7-1)//3]+1 = 3 votes to get
+//! confirmed but it only gets 1 from backing and 1 from malus so 2 in total)
+//!
+//!
+//! Attention: For usage with `zombienet` only!
+
+#![allow(missing_docs)]
+
+use futures::channel::oneshot;
+use pezkuwi_cli::{
+	service::{
+		AuxStore, Error, ExtendedOverseerGenArgs, Overseer, OverseerConnector, OverseerGen,
+		OverseerGenArgs, OverseerHandle,
+	},
+	validator_overseer_builder, Cli,
+};
+use pezkuwi_node_subsystem::SpawnGlue;
+use pezkuwi_node_subsystem_types::{ChainApiBackend, OverseerSignal, RuntimeApiSubsystemClient};
+use pezkuwi_node_subsystem_util::request_candidate_events;
+use pezkuwi_primitives::CandidateEvent;
+use sp_core::traits::SpawnNamed;
+
+// Filter wrapping related types.
+use crate::{interceptor::*, shared::MALUS};
+
+use std::sync::Arc;
+
+/// Wraps around ApprovalVotingSubsystem and replaces it.
+/// Listens to finalization messages and if possible triggers disputes for their ancestors.
+#[derive(Clone)]
+struct AncestorDisputer<Spawner> {
+	spawner: Spawner, //stores the actual ApprovalVotingSubsystem spawner
+	dispute_offset: u32, /* relative depth of the disputed block to the finalized block,
+	                   * 0=finalized, 1=parent of finalized etc */
+}
+
+impl<Sender, Spawner> MessageInterceptor<Sender> for AncestorDisputer<Spawner>
+where
+	Sender: overseer::ApprovalVotingSenderTrait + Clone + Send + 'static,
+	Spawner: overseer::gen::Spawner + Clone + 'static,
+{
+	type Message = ApprovalVotingMessage;
+
+	/// Intercept incoming `OverseerSignal::BlockFinalized' and pass the rest as normal.
+	fn intercept_incoming(
+		&self,
+		subsystem_sender: &mut Sender,
+		msg: FromOrchestra<Self::Message>,
+	) -> Option<FromOrchestra<Self::Message>> {
+		match msg {
+			FromOrchestra::Communication { msg } => Some(FromOrchestra::Communication { msg }),
+			FromOrchestra::Signal(OverseerSignal::BlockFinalized(
+				finalized_hash,
+				finalized_height,
+			)) => {
+				gum::debug!(
+					target: MALUS,
+					"😈 Block Finalization Interception! Block: {:?}", finalized_hash,
+				);
+
+				//Ensure that the chain is long enough for the target ancestor to exist
+				if finalized_height <= self.dispute_offset {
+					return Some(FromOrchestra::Signal(OverseerSignal::BlockFinalized(
+						finalized_hash,
+						finalized_height,
+					)));
+				}
+
+				let dispute_offset = self.dispute_offset;
+				let mut sender = subsystem_sender.clone();
+				self.spawner.spawn_blocking(
+					"malus-dispute-finalized-block",
+					Some("malus"),
+					Box::pin(async move {
+						// Query chain for the block hash at the target depth
+						let (tx, rx) = oneshot::channel();
+						sender
+							.send_message(ChainApiMessage::FinalizedBlockHash(
+								finalized_height - dispute_offset,
+								tx,
+							))
+							.await;
+						let disputable_hash = match rx.await {
+							Ok(Ok(Some(hash))) => {
+								gum::debug!(
+									target: MALUS,
+									"😈 Time to search {:?}`th ancestor! Block: {:?}", dispute_offset, hash,
+								);
+								hash
+							},
+							_ => {
+								gum::debug!(
+									target: MALUS,
+									"😈 Seems the target is not yet finalized! Nothing to dispute."
+								);
+								return; // Early return from the async block
+							},
+						};
+
+						// Fetch all candidate events for the target ancestor
+						let events =
+							request_candidate_events(disputable_hash, &mut sender).await.await;
+						let events = match events {
+							Ok(Ok(events)) => events,
+							Ok(Err(e)) => {
+								gum::error!(
+									target: MALUS,
+									"😈 Failed to fetch candidate events: {:?}", e
+								);
+								return; // Early return from the async block
+							},
+							Err(e) => {
+								gum::error!(
+									target: MALUS,
+									"😈 Failed to fetch candidate events: {:?}", e
+								);
+								return; // Early return from the async block
+							},
+						};
+
+						// Extract a token candidate from the events to use for disputing
+						let event = events.iter().find(|event| {
+							matches!(event, CandidateEvent::CandidateIncluded(_, _, _, _))
+						});
+						let candidate = match event {
+							Some(CandidateEvent::CandidateIncluded(candidate, _, _, _)) =>
+								candidate,
+							_ => {
+								gum::error!(
+									target: MALUS,
+									"😈 No candidate included event found! Nothing to dispute."
+								);
+								return; // Early return from the async block
+							},
+						};
+
+						// Extract the candidate hash from the candidate
+						let candidate_hash = candidate.hash();
+
+						// Fetch the session index for the candidate
+						let (tx, rx) = oneshot::channel();
+						sender
+							.send_message(RuntimeApiMessage::Request(
+								disputable_hash,
+								RuntimeApiRequest::SessionIndexForChild(tx),
+							))
+							.await;
+						let session_index = match rx.await {
+							Ok(Ok(session_index)) => session_index,
+							_ => {
+								gum::error!(
+									target: MALUS,
+									"😈 Failed to fetch session index for candidate."
+								);
+								return; // Early return from the async block
+							},
+						};
+						gum::info!(
+							target: MALUS,
+							"😈 Disputing candidate with hash: {:?} in session {:?}", candidate_hash, session_index,
+						);
+
+						// Start dispute
+						sender.send_unbounded_message(
+							DisputeCoordinatorMessage::IssueLocalStatement(
+								session_index,
+								candidate_hash,
+								candidate.clone(),
+								false, // indicates candidate is invalid -> dispute starts
+							),
+						);
+					}),
+				);
+
+				// Passthrough the finalization signal as usual (using it as hook only)
+				Some(FromOrchestra::Signal(OverseerSignal::BlockFinalized(
+					finalized_hash,
+					finalized_height,
+				)))
+			},
+			FromOrchestra::Signal(signal) => Some(FromOrchestra::Signal(signal)),
+		}
+	}
+}
+
+//----------------------------------------------------------------------------------
+
+#[derive(Debug, clap::Parser)]
+#[clap(rename_all = "kebab-case")]
+#[allow(missing_docs)]
+pub struct DisputeFinalizedCandidatesOptions {
+	/// relative depth of the disputed block to the finalized block, 0=finalized, 1=parent of
+	/// finalized etc
+	#[clap(long, ignore_case = true, default_value_t = 2, value_parser = clap::value_parser!(u32).range(0..=50))]
+	pub dispute_offset: u32,
+
+	#[clap(flatten)]
+	pub cli: Cli,
+}
+
+/// DisputeFinalizedCandidates implementation wrapper which implements `OverseerGen` glue.
+pub(crate) struct DisputeFinalizedCandidates {
+	/// relative depth of the disputed block to the finalized block, 0=finalized, 1=parent of
+	/// finalized etc
+	pub dispute_offset: u32,
+}
+
+impl OverseerGen for DisputeFinalizedCandidates {
+	fn generate<Spawner, RuntimeClient>(
+		&self,
+		connector: OverseerConnector,
+		args: OverseerGenArgs<'_, Spawner, RuntimeClient>,
+		ext_args: Option<ExtendedOverseerGenArgs>,
+	) -> Result<(Overseer<SpawnGlue<Spawner>, Arc<RuntimeClient>>, OverseerHandle), Error>
+	where
+		RuntimeClient: RuntimeApiSubsystemClient + ChainApiBackend + AuxStore + 'static,
+		Spawner: 'static + SpawnNamed + Clone + Unpin,
+	{
+		gum::info!(
+			target: MALUS,
+			"😈 Started Malus node that disputes finalized blocks after they are {:?} finalizations deep.",
+			&self.dispute_offset,
+		);
+
+		let ancestor_disputer = AncestorDisputer {
+			spawner: SpawnGlue(args.spawner.clone()),
+			dispute_offset: self.dispute_offset,
+		};
+
+		validator_overseer_builder(
+			args,
+			ext_args.expect("Extended arguments required to build validator overseer are provided"),
+		)?
+		.replace_approval_voting(move |cb| InterceptedSubsystem::new(cb, ancestor_disputer))
+		.build_with_connector(connector)
+		.map_err(|e| e.into())
+	}
+}

pezkuwi/node/malus/src/variants/dispute_valid_candidates.rs

@@ -0,0 +1,103 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+//! A malicious node that replaces approvals with invalid disputes
+//! against valid candidates. Additionally, the malus node can be configured to
+//! fake candidate validation and return a static result for candidate checking.
+//!
+//! Attention: For usage with `zombienet` only!
+
+#![allow(missing_docs)]
+
+use pezkuwi_cli::{
+	service::{
+		AuxStore, Error, ExtendedOverseerGenArgs, Overseer, OverseerConnector, OverseerGen,
+		OverseerGenArgs, OverseerHandle,
+	},
+	validator_overseer_builder, Cli,
+};
+use pezkuwi_node_subsystem::SpawnGlue;
+use pezkuwi_node_subsystem_types::{ChainApiBackend, RuntimeApiSubsystemClient};
+use sp_core::traits::SpawnNamed;
+
+// Filter wrapping related types.
+use super::common::{FakeCandidateValidation, FakeCandidateValidationError};
+use crate::{interceptor::*, variants::ReplaceValidationResult};
+
+use std::sync::Arc;
+
+#[derive(Debug, clap::Parser)]
+#[command(rename_all = "kebab-case")]
+#[allow(missing_docs)]
+pub struct DisputeAncestorOptions {
+	/// Malicious candidate validation subsystem configuration. When enabled, node PVF execution is
+	/// skipped during backing and/or approval and it's result can by specified by this option and
+	/// `--fake-validation-error` for invalid candidate outcomes.
+	#[arg(long, value_enum, ignore_case = true, default_value_t = FakeCandidateValidation::BackingAndApprovalInvalid)]
+	pub fake_validation: FakeCandidateValidation,
+
+	/// Applies only when `--fake-validation` is configured to reject candidates as invalid. It
+	/// allows to specify the exact error to return from the malicious candidate validation
+	/// subsystem.
+	#[arg(long, value_enum, ignore_case = true, default_value_t = FakeCandidateValidationError::InvalidOutputs)]
+	pub fake_validation_error: FakeCandidateValidationError,
+
+	/// Determines the percentage of candidates that should be disputed. Allows for fine-tuning
+	/// the intensity of the behavior of the malicious node. Value must be in the range [0..=100].
+	#[clap(short, long, ignore_case = true, default_value_t = 100, value_parser = clap::value_parser!(u8).range(0..=100))]
+	pub percentage: u8,
+
+	#[clap(flatten)]
+	pub cli: Cli,
+}
+
+pub(crate) struct DisputeValidCandidates {
+	/// Fake validation config (applies to disputes as well).
+	pub fake_validation: FakeCandidateValidation,
+	/// Fake validation error config.
+	pub fake_validation_error: FakeCandidateValidationError,
+	/// The probability of behaving maliciously.
+	pub percentage: u8,
+}
+
+impl OverseerGen for DisputeValidCandidates {
+	fn generate<Spawner, RuntimeClient>(
+		&self,
+		connector: OverseerConnector,
+		args: OverseerGenArgs<'_, Spawner, RuntimeClient>,
+		ext_args: Option<ExtendedOverseerGenArgs>,
+	) -> Result<(Overseer<SpawnGlue<Spawner>, Arc<RuntimeClient>>, OverseerHandle), Error>
+	where
+		RuntimeClient: RuntimeApiSubsystemClient + ChainApiBackend + AuxStore + 'static,
+		Spawner: 'static + SpawnNamed + Clone + Unpin,
+	{
+		let validation_filter = ReplaceValidationResult::new(
+			self.fake_validation,
+			self.fake_validation_error,
+			f64::from(self.percentage),
+		);
+
+		validator_overseer_builder(
+			args,
+			ext_args.expect("Extended arguments required to build validator overseer are provided"),
+		)?
+		.replace_candidate_validation(move |cv_subsystem| {
+			InterceptedSubsystem::new(cv_subsystem, validation_filter)
+		})
+		.build_with_connector(connector)
+		.map_err(|e| e.into())
+	}
+}

pezkuwi/node/malus/src/variants/mod.rs

@@ -0,0 +1,35 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Collection of behavior variants.
+
+mod back_garbage_candidate;
+mod common;
+mod dispute_finalized_candidates;
+mod dispute_valid_candidates;
+mod spam_statement_requests;
+mod suggest_garbage_candidate;
+mod support_disabled;
+
+pub(crate) use self::{
+	back_garbage_candidate::{BackGarbageCandidateOptions, BackGarbageCandidates},
+	dispute_finalized_candidates::{DisputeFinalizedCandidates, DisputeFinalizedCandidatesOptions},
+	dispute_valid_candidates::{DisputeAncestorOptions, DisputeValidCandidates},
+	spam_statement_requests::{SpamStatementRequests, SpamStatementRequestsOptions},
+	suggest_garbage_candidate::{SuggestGarbageCandidateOptions, SuggestGarbageCandidates},
+	support_disabled::{SupportDisabled, SupportDisabledOptions},
+};
+pub(crate) use common::*;

pezkuwi/node/malus/src/variants/spam_statement_requests.rs

@@ -0,0 +1,155 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+//! A malicious node variant that attempts spam statement requests.
+//!
+//! This malus variant behaves honestly in everything except when propagating statement distribution
+//! requests through the network bridge subsystem. Instead of sending a single request when it needs
+//! something it attempts to spam the peer with multiple requests.
+//!
+//! Attention: For usage with `zombienet` only!
+
+#![allow(missing_docs)]
+
+use pezkuwi_cli::{
+	service::{
+		AuxStore, Error, ExtendedOverseerGenArgs, Overseer, OverseerConnector, OverseerGen,
+		OverseerGenArgs, OverseerHandle,
+	},
+	validator_overseer_builder, Cli,
+};
+use pezkuwi_node_network_protocol::request_response::{outgoing::Requests, OutgoingRequest};
+use pezkuwi_node_subsystem::{messages::NetworkBridgeTxMessage, SpawnGlue};
+use pezkuwi_node_subsystem_types::{ChainApiBackend, RuntimeApiSubsystemClient};
+use sp_core::traits::SpawnNamed;
+
+// Filter wrapping related types.
+use crate::{interceptor::*, shared::MALUS};
+
+use std::sync::Arc;
+
+/// Wraps around network bridge and replaces it.
+#[derive(Clone)]
+struct RequestSpammer {
+	spam_factor: u32, // How many statement distribution requests to send.
+}
+
+impl<Sender> MessageInterceptor<Sender> for RequestSpammer
+where
+	Sender: overseer::NetworkBridgeTxSenderTrait + Clone + Send + 'static,
+{
+	type Message = NetworkBridgeTxMessage;
+
+	/// Intercept NetworkBridgeTxMessage::SendRequests with Requests::AttestedCandidateV2 inside and
+	/// duplicate that request
+	fn intercept_incoming(
+		&self,
+		_subsystem_sender: &mut Sender,
+		msg: FromOrchestra<Self::Message>,
+	) -> Option<FromOrchestra<Self::Message>> {
+		match msg {
+			FromOrchestra::Communication {
+				msg: NetworkBridgeTxMessage::SendRequests(requests, if_disconnected),
+			} => {
+				let mut new_requests = Vec::new();
+
+				for request in requests {
+					match request {
+						Requests::AttestedCandidateV2(ref req) => {
+							// Temporarily store peer and payload for duplication
+							let peer_to_duplicate = req.peer.clone();
+							let payload_to_duplicate = req.payload.clone();
+							// Push the original request
+							new_requests.push(request);
+
+							// Duplicate for spam purposes
+							gum::info!(
+								target: MALUS,
+								"😈 Duplicating AttestedCandidateV2 request extra {:?} times to peer: {:?}.", self.spam_factor, peer_to_duplicate,
+							);
+							new_requests.extend((0..self.spam_factor - 1).map(|_| {
+								let (new_outgoing_request, _) = OutgoingRequest::new(
+									peer_to_duplicate.clone(),
+									payload_to_duplicate.clone(),
+								);
+								Requests::AttestedCandidateV2(new_outgoing_request)
+							}));
+						},
+						_ => {
+							new_requests.push(request);
+						},
+					}
+				}
+
+				// Passthrough the message with a potentially modified number of requests
+				Some(FromOrchestra::Communication {
+					msg: NetworkBridgeTxMessage::SendRequests(new_requests, if_disconnected),
+				})
+			},
+			FromOrchestra::Communication { msg } => Some(FromOrchestra::Communication { msg }),
+			FromOrchestra::Signal(signal) => Some(FromOrchestra::Signal(signal)),
+		}
+	}
+}
+
+//----------------------------------------------------------------------------------
+
+#[derive(Debug, clap::Parser)]
+#[clap(rename_all = "kebab-case")]
+#[allow(missing_docs)]
+pub struct SpamStatementRequestsOptions {
+	/// How many statement distribution requests to send.
+	#[clap(long, ignore_case = true, default_value_t = 1000, value_parser = clap::value_parser!(u32).range(0..=10000000))]
+	pub spam_factor: u32,
+
+	#[clap(flatten)]
+	pub cli: Cli,
+}
+
+/// SpamStatementRequests implementation wrapper which implements `OverseerGen` glue.
+pub(crate) struct SpamStatementRequests {
+	/// How many statement distribution requests to send.
+	pub spam_factor: u32,
+}
+
+impl OverseerGen for SpamStatementRequests {
+	fn generate<Spawner, RuntimeClient>(
+		&self,
+		connector: OverseerConnector,
+		args: OverseerGenArgs<'_, Spawner, RuntimeClient>,
+		ext_args: Option<ExtendedOverseerGenArgs>,
+	) -> Result<(Overseer<SpawnGlue<Spawner>, Arc<RuntimeClient>>, OverseerHandle), Error>
+	where
+		RuntimeClient: RuntimeApiSubsystemClient + ChainApiBackend + AuxStore + 'static,
+		Spawner: 'static + SpawnNamed + Clone + Unpin,
+	{
+		gum::info!(
+			target: MALUS,
+			"😈 Started Malus node that duplicates each statement distribution request spam_factor = {:?} times.",
+			&self.spam_factor,
+		);
+
+		let request_spammer = RequestSpammer { spam_factor: self.spam_factor };
+
+		validator_overseer_builder(
+			args,
+			ext_args.expect("Extended arguments required to build validator overseer are provided"),
+		)?
+		.replace_network_bridge_tx(move |cb| InterceptedSubsystem::new(cb, request_spammer))
+		.build_with_connector(connector)
+		.map_err(|e| e.into())
+	}
+}

pezkuwi/node/malus/src/variants/suggest_garbage_candidate.rs

@@ -0,0 +1,313 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+//! A malicious node that stores bogus availability chunks, preventing others from
+//! doing approval voting. This should lead to disputes depending if the validator
+//! has fetched a malicious chunk.
+//!
+//! Attention: For usage with `zombienet` only!
+
+#![allow(missing_docs)]
+
+use futures::channel::oneshot;
+use pezkuwi_cli::{
+	service::{
+		AuxStore, Error, ExtendedOverseerGenArgs, Overseer, OverseerConnector, OverseerGen,
+		OverseerGenArgs, OverseerHandle,
+	},
+	validator_overseer_builder, Cli,
+};
+use pezkuwi_node_primitives::{AvailableData, BlockData, PoV};
+use pezkuwi_node_subsystem_types::{ChainApiBackend, RuntimeApiSubsystemClient};
+use pezkuwi_primitives::{CandidateDescriptorV2, CandidateReceiptV2, CoreIndex};
+
+use pezkuwi_node_subsystem_util::request_validators;
+use sp_core::traits::SpawnNamed;
+
+use rand::distributions::{Bernoulli, Distribution};
+
+// Filter wrapping related types.
+use crate::{
+	interceptor::*,
+	shared::{MALICIOUS_POV, MALUS},
+	variants::{
+		create_fake_candidate_commitments, FakeCandidateValidation, FakeCandidateValidationError,
+		ReplaceValidationResult,
+	},
+};
+
+// Import extra types relevant to the particular
+// subsystem.
+use pezkuwi_node_subsystem::SpawnGlue;
+
+use std::sync::Arc;
+
+/// Replace outgoing approval messages with disputes.
+#[derive(Clone)]
+struct NoteCandidate<Spawner> {
+	spawner: Spawner,
+	percentage: f64,
+}
+
+impl<Sender, Spawner> MessageInterceptor<Sender> for NoteCandidate<Spawner>
+where
+	Sender: overseer::CandidateBackingSenderTrait + Clone + Send + 'static,
+	Spawner: overseer::gen::Spawner + Clone + 'static,
+{
+	type Message = CandidateBackingMessage;
+
+	/// Intercept incoming `Second` requests from the `collator-protocol` subsystem.
+	fn intercept_incoming(
+		&self,
+		subsystem_sender: &mut Sender,
+		msg: FromOrchestra<Self::Message>,
+	) -> Option<FromOrchestra<Self::Message>> {
+		match msg {
+			FromOrchestra::Communication {
+				msg:
+					CandidateBackingMessage::Second(
+						relay_parent,
+						ref candidate,
+						ref validation_data,
+						ref _pov,
+					),
+			} => {
+				gum::debug!(
+					target: MALUS,
+					candidate_hash = ?candidate.hash(),
+					?relay_parent,
+					"Received request to second candidate",
+				);
+
+				// Need to draw value from Bernoulli distribution with given probability of success
+				// defined by the clap parameter. Note that clap parameter must be f64 since this is
+				// expected by the Bernoulli::new() function. It must be converted from u8, due to
+				// the lack of support for the .range() call on u64 in the clap crate.
+				let distribution = Bernoulli::new(self.percentage / 100.0)
+					.expect("Invalid probability! Percentage must be in range [0..=100].");
+
+				// Draw a random boolean from the Bernoulli distribution with probability of true
+				// equal to `p`. We use `rand::thread_rng` as the source of randomness.
+				let generate_malicious_candidate = distribution.sample(&mut rand::thread_rng());
+
+				if generate_malicious_candidate {
+					gum::debug!(target: MALUS, "😈 Suggesting malicious candidate.",);
+
+					let pov = PoV { block_data: BlockData(MALICIOUS_POV.into()) };
+
+					let (sender, receiver) = std::sync::mpsc::channel();
+					let mut new_sender = subsystem_sender.clone();
+					let _candidate = candidate.clone();
+					let validation_data = validation_data.clone();
+					self.spawner.spawn_blocking(
+						"malus-get-validation-data",
+						Some("malus"),
+						Box::pin(async move {
+							gum::trace!(target: MALUS, "Requesting validators");
+							let n_validators = request_validators(relay_parent, &mut new_sender)
+								.await
+								.await
+								.unwrap()
+								.unwrap()
+								.len();
+							gum::trace!(target: MALUS, "Validators {}", n_validators);
+
+							let validation_code = {
+								let validation_code_hash =
+									_candidate.descriptor().validation_code_hash();
+								let (tx, rx) = oneshot::channel();
+								new_sender
+									.send_message(RuntimeApiMessage::Request(
+										relay_parent,
+										RuntimeApiRequest::ValidationCodeByHash(
+											validation_code_hash,
+											tx,
+										),
+									))
+									.await;
+
+								let code = rx.await.expect("Querying the RuntimeApi should work");
+								match code {
+									Err(e) => {
+										gum::error!(
+											target: MALUS,
+											?validation_code_hash,
+											error = %e,
+											"Failed to fetch validation code",
+										);
+
+										sender.send(None).expect("channel is still open");
+										return;
+									},
+									Ok(None) => {
+										gum::debug!(
+											target: MALUS,
+											?validation_code_hash,
+											"Could not find validation code on chain",
+										);
+
+										sender.send(None).expect("channel is still open");
+										return;
+									},
+									Ok(Some(c)) => c,
+								}
+							};
+
+							sender
+								.send(Some((validation_data, validation_code, n_validators)))
+								.expect("channel is still open");
+						}),
+					);
+
+					let (validation_data, validation_code, n_validators) =
+						receiver.recv().unwrap()?;
+
+					let validation_data_hash = validation_data.hash();
+					let validation_code_hash = validation_code.hash();
+					let validation_data_relay_parent_number = validation_data.relay_parent_number;
+
+					gum::trace!(
+						target: MALUS,
+						candidate_hash = ?candidate.hash(),
+						?relay_parent,
+						?n_validators,
+						?validation_data_hash,
+						?validation_code_hash,
+						?validation_data_relay_parent_number,
+						"Fetched validation data."
+					);
+
+					let malicious_available_data = AvailableData {
+						pov: Arc::new(pov.clone()),
+						validation_data: validation_data.clone(),
+					};
+
+					let pov_hash = pov.hash();
+					let erasure_root = {
+						let chunks = pezkuwi_erasure_coding::obtain_chunks_v1(
+							n_validators as usize,
+							&malicious_available_data,
+						)
+						.unwrap();
+
+						let branches = pezkuwi_erasure_coding::branches(chunks.as_ref());
+						branches.root()
+					};
+
+					let malicious_commitments = create_fake_candidate_commitments(
+						&malicious_available_data.validation_data,
+					);
+
+					let malicious_candidate = CandidateReceiptV2 {
+						descriptor: CandidateDescriptorV2::new(
+							candidate.descriptor.para_id(),
+							relay_parent,
+							candidate.descriptor.core_index().unwrap_or(CoreIndex(0)),
+							candidate.descriptor.session_index().unwrap_or(0),
+							validation_data_hash,
+							pov_hash,
+							erasure_root,
+							malicious_commitments.head_data.hash(),
+							validation_code_hash,
+						),
+						commitments_hash: malicious_commitments.hash(),
+					};
+					let malicious_candidate_hash = malicious_candidate.hash();
+
+					let message = FromOrchestra::Communication {
+						msg: CandidateBackingMessage::Second(
+							relay_parent,
+							malicious_candidate,
+							validation_data,
+							pov,
+						),
+					};
+
+					gum::info!(
+						target: MALUS,
+						candidate_hash = ?candidate.hash(),
+						"😈 Intercepted CandidateBackingMessage::Second and created malicious candidate with hash: {:?}",
+						&malicious_candidate_hash
+					);
+					Some(message)
+				} else {
+					Some(msg)
+				}
+			},
+			FromOrchestra::Communication { msg } => Some(FromOrchestra::Communication { msg }),
+			FromOrchestra::Signal(signal) => Some(FromOrchestra::Signal(signal)),
+		}
+	}
+}
+
+#[derive(Debug, clap::Parser)]
+#[clap(rename_all = "kebab-case")]
+#[allow(missing_docs)]
+pub struct SuggestGarbageCandidateOptions {
+	/// Determines the percentage of malicious candidates that are suggested by malus,
+	/// based on the total number of intercepted CandidateBacking
+	/// Must be in the range [0..=100].
+	#[clap(short, long, ignore_case = true, default_value_t = 100, value_parser = clap::value_parser!(u8).range(0..=100))]
+	pub percentage: u8,
+
+	#[clap(flatten)]
+	pub cli: Cli,
+}
+
+/// Garbage candidate implementation wrapper which implements `OverseerGen` glue.
+pub(crate) struct SuggestGarbageCandidates {
+	/// The probability of behaving maliciously.
+	pub percentage: u8,
+}
+
+impl OverseerGen for SuggestGarbageCandidates {
+	fn generate<Spawner, RuntimeClient>(
+		&self,
+		connector: OverseerConnector,
+		args: OverseerGenArgs<'_, Spawner, RuntimeClient>,
+		ext_args: Option<ExtendedOverseerGenArgs>,
+	) -> Result<(Overseer<SpawnGlue<Spawner>, Arc<RuntimeClient>>, OverseerHandle), Error>
+	where
+		RuntimeClient: RuntimeApiSubsystemClient + ChainApiBackend + AuxStore + 'static,
+		Spawner: 'static + SpawnNamed + Clone + Unpin,
+	{
+		gum::info!(
+			target: MALUS,
+			"😈 Started Malus node with a {:?} percent chance of behaving maliciously for a given candidate.",
+			&self.percentage,
+		);
+
+		let note_candidate = NoteCandidate {
+			spawner: SpawnGlue(args.spawner.clone()),
+			percentage: f64::from(self.percentage),
+		};
+		let fake_valid_probability = 100.0;
+		let validation_filter = ReplaceValidationResult::new(
+			FakeCandidateValidation::BackingAndApprovalValid,
+			FakeCandidateValidationError::InvalidOutputs,
+			fake_valid_probability,
+		);
+
+		validator_overseer_builder(
+			args,
+			ext_args.expect("Extended arguments required to build validator overseer are provided"),
+		)?
+		.replace_candidate_backing(move |cb| InterceptedSubsystem::new(cb, note_candidate))
+		.replace_candidate_validation(move |cb| InterceptedSubsystem::new(cb, validation_filter))
+		.build_with_connector(connector)
+		.map_err(|e| e.into())
+	}
+}

pezkuwi/node/malus/src/variants/support_disabled.rs

@@ -0,0 +1,96 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Pezkuwi.
+
+// Pezkuwi 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.
+
+// Pezkuwi 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 Pezkuwi.  If not, see <http://www.gnu.org/licenses/>.
+
+//! This variant of Malus overrides the `disabled_validators` runtime API
+//! to always return an empty set of disabled validators.
+
+use pezkuwi_cli::{
+	service::{
+		AuxStore, Error, ExtendedOverseerGenArgs, Overseer, OverseerConnector, OverseerGen,
+		OverseerGenArgs, OverseerHandle,
+	},
+	validator_overseer_builder, Cli,
+};
+use pezkuwi_node_subsystem::SpawnGlue;
+use pezkuwi_node_subsystem_types::{ChainApiBackend, RuntimeApiSubsystemClient};
+use sp_core::traits::SpawnNamed;
+
+use crate::interceptor::*;
+
+use std::sync::Arc;
+
+#[derive(Debug, clap::Parser)]
+#[clap(rename_all = "kebab-case")]
+#[allow(missing_docs)]
+pub struct SupportDisabledOptions {
+	#[clap(flatten)]
+	pub cli: Cli,
+}
+
+/// Generates an overseer with a custom runtime API subsystem.
+pub(crate) struct SupportDisabled;
+
+impl OverseerGen for SupportDisabled {
+	fn generate<Spawner, RuntimeClient>(
+		&self,
+		connector: OverseerConnector,
+		args: OverseerGenArgs<'_, Spawner, RuntimeClient>,
+		ext_args: Option<ExtendedOverseerGenArgs>,
+	) -> Result<(Overseer<SpawnGlue<Spawner>, Arc<RuntimeClient>>, OverseerHandle), Error>
+	where
+		RuntimeClient: RuntimeApiSubsystemClient + ChainApiBackend + AuxStore + 'static,
+		Spawner: 'static + SpawnNamed + Clone + Unpin,
+	{
+		validator_overseer_builder(
+			args,
+			ext_args.expect("Extended arguments required to build validator overseer are provided"),
+		)?
+		.replace_runtime_api(move |ra_subsystem| {
+			InterceptedSubsystem::new(ra_subsystem, IgnoreDisabled)
+		})
+		.build_with_connector(connector)
+		.map_err(|e| e.into())
+	}
+}
+
+#[derive(Clone)]
+struct IgnoreDisabled;
+
+impl<Sender> MessageInterceptor<Sender> for IgnoreDisabled
+where
+	Sender: overseer::RuntimeApiSenderTrait + Clone + Send + 'static,
+{
+	type Message = RuntimeApiMessage;
+
+	/// Intercept incoming runtime api requests.
+	fn intercept_incoming(
+		&self,
+		_subsystem_sender: &mut Sender,
+		msg: FromOrchestra<Self::Message>,
+	) -> Option<FromOrchestra<Self::Message>> {
+		match msg {
+			FromOrchestra::Communication {
+				msg:
+					RuntimeApiMessage::Request(_relay_parent, RuntimeApiRequest::DisabledValidators(tx)),
+			} => {
+				let _ = tx.send(Ok(Vec::new()));
+				None
+			},
+			FromOrchestra::Communication { msg } => Some(FromOrchestra::Communication { msg }),
+			FromOrchestra::Signal(signal) => Some(FromOrchestra::Signal(signal)),
+		}
+	}
+}