node: Implement signature verification

Signed-off-by: Alexis Sellier <self@cloudhead.io>

node/src/protocol/message.rs

@@ -58,6 +58,14 @@ pub struct NodeAnnouncement {
     addresses: Vec<Address>,
 }
 
+impl NodeAnnouncement {
+    /// Verify a signature on this message.
+    pub fn verify(&self, signature: &crypto::Signature) -> bool {
+        let msg = serde_json::to_vec(self).unwrap();
+        self.id.verify(signature, &msg).is_ok()
+    }
+}
+
 /// Message payload.
 /// These are the messages peers send to each other.
 #[derive(Debug, Serialize, Deserialize, Clone)]
@@ -110,6 +118,16 @@ impl Message {
         }
     }
 
+    pub fn node<S: crypto::Signer>(announcement: NodeAnnouncement, signer: S) -> Self {
+        let msg = serde_json::to_vec(&announcement).unwrap();
+        let signature = signer.sign(&msg);
+
+        Self::Node {
+            signature,
+            announcement,
+        }
+    }
+
     pub fn inventory<S, T, G>(ctx: &mut Context<S, T, G>) -> Result<Self, storage::Error>
     where
         T: storage::ReadStorage,

node/src/protocol/peer.rs

@@ -194,7 +194,16 @@ impl Peer {
                     }));
                 }
             }
-            (PeerState::Negotiated { .. }, Message::Node { .. }) => {
+            (
+                PeerState::Negotiated { .. },
+                Message::Node {
+                    announcement,
+                    signature,
+                },
+            ) => {
+                if !announcement.verify(&signature) {
+                    return Err(PeerError::Misbehavior);
+                }
                 todo!();
             }
             (PeerState::Negotiated { .. }, Message::Hello { .. }) => {