feat(gossip): add accredited_keys placeholder (for future Join/Leave)

lez/sequencer/core/src/gossip/keys_provider.rs

@@ -0,0 +1,82 @@
+//! Source of the channel's current accredited key set, polled by the
+//! gossip layer to validate announcements.
+//!
+//! FIXME: `NodeKeysProvider` will be replaced by an L2 Join/Leave-derived provider in a follow-up.
+
+use std::{collections::HashSet, future::Future};
+
+use anyhow::{Context as _, Result};
+use logos_blockchain_core::mantle::ops::channel::ChannelId;
+use logos_blockchain_zone_sdk::{
+    CommonHttpClient,
+    adapter::{Node as _, NodeHttpClient},
+};
+
+use crate::config::BedrockConfig;
+
+pub trait AccreditedKeysProvider: Send + 'static {
+    /// The channel's current accredited Ed25519 keys. An empty set is valid
+    /// (channel does not exist yet); errors keep the caller's last set.
+    fn accredited_keys(&self) -> impl Future<Output = Result<HashSet<[u8; 32]>>> + Send;
+}
+
+/// Reads accredited keys from the bedrock node's channel state, on its own
+/// HTTP connection (no coupling to the publisher's drive task).
+pub struct NodeKeysProvider {
+    node: NodeHttpClient,
+    channel_id: ChannelId,
+}
+
+impl NodeKeysProvider {
+    #[must_use]
+    pub fn new(config: &BedrockConfig) -> Self {
+        let node = NodeHttpClient::new(
+            CommonHttpClient::new(config.auth.clone().map(Into::into)),
+            config.node_url.clone(),
+        );
+        Self {
+            node,
+            channel_id: config.channel_id,
+        }
+    }
+}
+
+impl AccreditedKeysProvider for NodeKeysProvider {
+    async fn accredited_keys(&self) -> Result<HashSet<[u8; 32]>> {
+        let state = self
+            .node
+            .channel_state(self.channel_id)
+            .await
+            .context("Failed to read channel state for accredited keys")?;
+        Ok(state
+            .map(|state| {
+                state
+                    .accredited_keys
+                    .iter()
+                    .map(|key| key.to_bytes())
+                    .collect()
+            })
+            .unwrap_or_default())
+    }
+}
+
+/// Fixed key set, for tests.
+pub struct StaticKeysProvider(pub HashSet<[u8; 32]>);
+
+impl AccreditedKeysProvider for StaticKeysProvider {
+    async fn accredited_keys(&self) -> Result<HashSet<[u8; 32]>> {
+        Ok(self.0.clone())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[tokio::test]
+    async fn static_provider_returns_its_set() {
+        let keys = HashSet::from([[1; 32], [2; 32]]);
+        let provider = StaticKeysProvider(keys.clone());
+        assert_eq!(provider.accredited_keys().await.unwrap(), keys);
+    }
+}

lez/sequencer/core/src/gossip/mod.rs

@@ -7,3 +7,4 @@
 
 pub mod announcement;
 pub mod directory;
+pub mod keys_provider;