feat(ffi): add extract_quic_network FFI for StoffelVM compatibility

mpc/src/ffi/c_bindings/network/mod.rs

@@ -1,5 +1,6 @@
 pub mod fake_network;
 pub mod quic;
+use std::ffi::c_void;
 use std::slice;
 use std::sync::Arc;
 
@@ -94,3 +95,54 @@ pub extern "C" fn network_send(
         Err(e) => return e.into(),
     }
 }
+
+/// Extract raw QuicNetworkManager pointer for use with external libraries.
+///
+/// This function extracts the inner `Arc<QuicNetworkManager>` from a `NetworkOpaque`
+/// pointer and returns it as a boxed Arc suitable for passing to libraries like StoffelVM
+/// that expect a raw `Arc<QuicNetworkManager>` pointer.
+///
+/// # Arguments
+/// * `network` - A pointer to NetworkOpaque (must wrap GenericNetwork::QuicNetworkManager)
+///
+/// # Returns
+/// * A pointer to a boxed `Arc<QuicNetworkManager>`, or null if:
+///   - The input pointer is null
+///   - The network is not a QuicNetworkManager variant
+///
+/// # Safety
+/// * The caller must ensure `network` is a valid NetworkOpaque pointer
+/// * The returned pointer must be freed with `free_raw_quic_network()` when no longer needed
+/// * The original NetworkOpaque remains valid and must be freed separately
+#[no_mangle]
+pub extern "C" fn extract_quic_network(network: *mut NetworkOpaque) -> *mut c_void {
+    if network.is_null() {
+        return std::ptr::null_mut();
+    }
+    let net = unsafe { &*(network as *mut GenericNetwork) };
+    match net {
+        GenericNetwork::QuicNetworkManager(arc) => {
+            // Box the Arc for stable FFI pointer (matches StoffelVM expectation)
+            Box::into_raw(Box::new(Arc::clone(arc))) as *mut c_void
+        }
+        _ => std::ptr::null_mut(),
+    }
+}
+
+/// Free a raw QuicNetworkManager pointer obtained from `extract_quic_network()`.
+///
+/// # Arguments
+/// * `ptr` - A pointer obtained from `extract_quic_network()`
+///
+/// # Safety
+/// * The pointer must have been obtained from `extract_quic_network()`
+/// * The pointer must not have been freed already
+/// * The pointer must not be used after this call
+#[no_mangle]
+pub extern "C" fn free_raw_quic_network(ptr: *mut c_void) {
+    if !ptr.is_null() {
+        unsafe {
+            let _ = Box::from_raw(ptr as *mut Arc<QuicNetworkManager>);
+        }
+    }
+}

mpc/src/ffi/c_bindings/network/quic.rs

@@ -85,6 +85,33 @@ pub extern "C" fn new_quic_network(
     Box::into_raw(Box::new(quic_network)) as *mut QuicNetworkOpaque
 }
 
+/// Creates a new QUIC network instance with a specific party ID
+///
+/// This is essential for MPC operations where parties need consistent IDs.
+/// The party_id will be used in handshakes and for connection lookups.
+///
+/// # Arguments
+/// * `party_id` - The party ID for this network node (e.g., 0, 1, 2, etc.)
+/// * `returned_connections` - Output parameter for peer connections map
+#[no_mangle]
+pub extern "C" fn new_quic_network_with_party_id(
+    party_id: usize,
+    returned_connections: *mut *mut QuicPeerConnectionsOpaque,
+) -> *mut QuicNetworkOpaque {
+    let quic_network = QuicNetwork {
+        quic_manager: QuicNetworkManager::with_node_id(party_id),
+    };
+    let peer_connections = QuicPeerConnections {
+        connections: HashMap::new(),
+    };
+    unsafe {
+        *returned_connections =
+            Box::into_raw(Box::new(peer_connections)) as *mut QuicPeerConnectionsOpaque;
+    }
+
+    Box::into_raw(Box::new(quic_network)) as *mut QuicNetworkOpaque
+}
+
 /// Establishes a connection to a new peer
 ///
 /// This method initiates an outgoing connection to a peer at the specified address.

mpc/src/ffi/honey_badger_bindings.h

@@ -279,6 +279,19 @@ void init_tls(void);
  */
 struct QuicNetworkOpaque *new_quic_network(struct QuicPeerConnectionsOpaque **returned_connections);
 
+/**
+ * Creates a new QUIC network instance with a specific party ID
+ *
+ * This is essential for MPC operations where parties need consistent IDs.
+ * The party_id will be used in handshakes and for connection lookups.
+ *
+ * # Arguments
+ * * `party_id` - The party ID for this network node (e.g., 0, 1, 2, etc.)
+ * * `returned_connections` - Output parameter for peer connections map
+ */
+struct QuicNetworkOpaque *new_quic_network_with_party_id(uintptr_t party_id,
+                                                          struct QuicPeerConnectionsOpaque **returned_connections);
+
 /**
  * Establishes a connection to a new peer
  *