fn compatible_upgrade()

in neqo-transport/src/tparams.rs [660:705]

• 44 lines of code
• 7 McCabe index (conditional complexity)

    fn compatible_upgrade(&mut self, remote_tp: &TransportParameters) -> Res<()> {
        if let Some((current, other)) = remote_tp.get_versions() {
            qtrace!(
                "Peer versions: {current:x} {other:x?}; config {:?}",
                self.versions,
            );

            if self.role == Role::Client {
                let chosen = Version::try_from(current)?;
                if self.versions.compatible().any(|&v| v == chosen) {
                    Ok(())
                } else {
                    qinfo!(
                        "Chosen version {current:x} is not compatible with initial version {:x}",
                        self.versions.initial().wire_version(),
                    );
                    Err(Error::TransportParameterError)
                }
            } else {
                if current != self.versions.initial().wire_version() {
                    qinfo!(
                        "Current version {current:x} != own version {:x}",
                        self.versions.initial().wire_version(),
                    );
                    return Err(Error::TransportParameterError);
                }

                if let Some(preferred) = self.versions.preferred_compatible(other) {
                    if preferred != self.versions.initial() {
                        qinfo!(
                            "Compatible upgrade {:?} ==> {preferred:?}",
                            self.versions.initial()
                        );
                        self.versions.set_initial(preferred);
                        self.local.compatible_upgrade(preferred);
                    }
                    Ok(())
                } else {
                    qinfo!("Unable to find any compatible version");
                    Err(Error::TransportParameterError)
                }
            }
        } else {
            Ok(())
        }
    }