huskies: merge 728_story_cryptographic_peer_handshake_with_trusted_keys_gating

server/src/crdt_sync/client.rs

@@ -11,7 +11,7 @@ use crate::slog_warn;
 
 use super::auth;
 use super::dispatch::{handle_incoming_binary, handle_incoming_text};
-use super::wire::{AuthMessage, ChallengeMessage, SyncMessage};
+use super::wire::{AuthMessage, ChallengeMessage, HelloMessage, ServerAuthMessage, SyncMessage};
 use super::{AUTH_TIMEOUT_SECS, PING_INTERVAL_SECS, PONG_TIMEOUT_SECS};
 
 #[allow(unused_imports)]
@@ -86,11 +86,79 @@ pub(crate) async fn connect_and_sync(url: &str, token: Option<&str>) -> Result<(
 
     let (mut sink, mut stream) = ws_stream.split();
 
-    slog!("[crdt-sync] Connected to rendezvous peer, awaiting challenge");
+    slog!("[crdt-sync] Connected to rendezvous peer, starting mutual-auth handshake");
 
-    // ── Step 1: Receive challenge from listener ───────────────────
     use tokio_tungstenite::tungstenite::Message as TungsteniteMsg;
 
+    // ── Step 1: Send hello with a fresh client nonce ──────────────
+    let client_nonce = crate::node_identity::generate_challenge();
+    let hello = HelloMessage {
+        r#type: "hello".to_string(),
+        nonce: client_nonce.clone(),
+    };
+    let hello_json = serde_json::to_string(&hello).map_err(|e| format!("Serialize hello: {e}"))?;
+    sink.send(TungsteniteMsg::Text(hello_json.into()))
+        .await
+        .map_err(|e| format!("Send hello failed: {e}"))?;
+
+    slog!("[crdt-sync] Hello sent, awaiting server_auth");
+
+    // ── Step 2: Receive server_auth from the responding node ──────
+    let server_auth_frame = tokio::time::timeout(
+        std::time::Duration::from_secs(AUTH_TIMEOUT_SECS),
+        stream.next(),
+    )
+    .await
+    .map_err(|_| "Auth timeout waiting for server_auth".to_string())?
+    .ok_or_else(|| "Connection closed before server_auth".to_string())?
+    .map_err(|e| format!("WebSocket read error: {e}"))?;
+
+    let server_auth_text = match server_auth_frame {
+        TungsteniteMsg::Text(t) => t.to_string(),
+        _ => return Err("Expected text frame for server_auth".to_string()),
+    };
+
+    let server_auth: ServerAuthMessage = serde_json::from_str(&server_auth_text)
+        .map_err(|e| format!("Invalid server_auth message: {e}"))?;
+
+    if server_auth.r#type != "server_auth" {
+        return Err(format!(
+            "Expected server_auth message, got type={}",
+            server_auth.r#type
+        ));
+    }
+
+    // ── Step 3: Verify server's signature and check trusted-key list ─
+    let versioned_challenge = format!("huskies-v1:{client_nonce}");
+    let server_sig_valid = crate::node_identity::verify_message_strict(
+        &server_auth.pubkey_hex,
+        versioned_challenge.as_bytes(),
+        &server_auth.signature_hex,
+    );
+    let server_key_trusted = auth::trusted_keys()
+        .iter()
+        .any(|k| k == &server_auth.pubkey_hex);
+
+    if !server_sig_valid || !server_key_trusted {
+        slog!(
+            "[crdt-sync] Server auth failed \
+             (sig_valid={server_sig_valid}, key_trusted={server_key_trusted}, \
+             server_pubkey={})",
+            server_auth.pubkey_hex
+        );
+        return Err(format!(
+            "Server auth rejected: sig_valid={server_sig_valid}, \
+             key_trusted={server_key_trusted}, server_pubkey={}",
+            server_auth.pubkey_hex
+        ));
+    }
+
+    slog!(
+        "[crdt-sync] Server authenticated: {:.12}…",
+        &server_auth.pubkey_hex
+    );
+
+    // ── Step 4: Receive challenge from the responding node ────────
     let challenge_frame = tokio::time::timeout(
         std::time::Duration::from_secs(AUTH_TIMEOUT_SECS),
         stream.next(),
@@ -115,7 +183,7 @@ pub(crate) async fn connect_and_sync(url: &str, token: Option<&str>) -> Result<(
         ));
     }
 
-    // ── Step 2: Sign challenge and send auth reply ────────────────
+    // ── Step 5: Sign challenge and send auth reply ────────────────
     let (pubkey_hex, signature_hex) = crdt_state::sign_challenge(&challenge_msg.nonce)
         .ok_or_else(|| "CRDT not initialised — cannot sign challenge".to_string())?;