Sealed sender v2: add an InvalidRegistrationId exception/error

This dedicated error is thrown when a recipient has a registration ID
that's out of the range used by Signal [0, 0x3FFF]. These IDs cannot
be encoded in the sealed sender v2 format and are not supported, even
though they don't cause any problems for 1:1 messages.

rust/bridge/ffi/src/lib.rs

@@ -12,6 +12,7 @@ use libsignal_bridge::ffi::*;
 use libsignal_protocol::*;
 use std::convert::TryFrom;
 use std::ffi::{c_void, CString};
+use std::panic::AssertUnwindSafe;
 
 pub mod logging;
 mod util;
@@ -58,6 +59,31 @@ pub unsafe extern "C" fn signal_error_get_message(
     }
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn signal_error_get_address(
+    err: *const SignalFfiError,
+    out: *mut *mut ProtocolAddress,
+) -> *mut SignalFfiError {
+    let err = AssertUnwindSafe(err);
+    run_ffi_safe(|| {
+        let err = err.as_ref().ok_or(SignalFfiError::NullPointer)?;
+        match err {
+            SignalFfiError::Signal(SignalProtocolError::InvalidRegistrationId(addr, _value)) => {
+                box_object(out, Ok(addr.clone()))?;
+            }
+            _ => {
+                return Err(SignalFfiError::Signal(
+                    SignalProtocolError::InvalidArgument(format!(
+                        "cannot get address from error ({})",
+                        err
+                    )),
+                ));
+            }
+        }
+        Ok(())
+    })
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn signal_error_get_type(err: *const SignalFfiError) -> u32 {
     match err.as_ref() {