+ /// Sets the feature's optional (odd) bit in the given flags.
+ #[inline]
+ fn set_optional_bit(flags: &mut Vec<u8>) {
+ if flags.len() <= Self::BYTE_OFFSET {
+ flags.resize(Self::BYTE_OFFSET + 1, 0u8);
+ }
+
+ flags[Self::BYTE_OFFSET] |= Self::OPTIONAL_MASK;
+ }
+
+ /// Clears the feature's required (even) and optional (odd) bits from the given
+ /// flags.
+ #[inline]
+ fn clear_bits(flags: &mut Vec<u8>) {
+ if flags.len() > Self::BYTE_OFFSET {
+ flags[Self::BYTE_OFFSET] &= !Self::REQUIRED_MASK;
+ flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
+ }
+
+ let last_non_zero_byte = flags.iter().rposition(|&byte| byte != 0);
+ let size = if let Some(offset) = last_non_zero_byte { offset + 1 } else { 0 };
+ flags.resize(size, 0u8);
+ }
+ }
+
+ impl <T: $feature> Features<T> {
+ /// Set this feature as optional.
+ pub fn $optional_setter(mut self) -> Self {
+ <T as $feature>::set_optional_bit(&mut self.flags);
+ self
+ }
+
+ /// Set this feature as required.
+ pub fn $required_setter(mut self) -> Self {
+ <T as $feature>::set_required_bit(&mut self.flags);
+ self
+ }
+
+ /// Checks if this feature is supported.
+ pub fn $supported_getter(&self) -> bool {
+ <T as $feature>::supports_feature(&self.flags)
+ }
+ }
+
+ $(
+ impl $feature for $context {
+ // EVEN_BIT % 2 == 0
+ const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
+
+ // ODD_BIT % 2 == 1
+ const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
+ }
+ )*
+ };
+ ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
+ $required_setter: ident, $supported_getter: ident, $required_getter: ident) => {
+ define_feature!($odd_bit, $feature, [$($context),+], $doc, $optional_setter, $required_setter, $supported_getter);
+ impl <T: $feature> Features<T> {
+ /// Checks if this feature is required.
+ pub fn $required_getter(&self) -> bool {
+ <T as $feature>::requires_feature(&self.flags)
+ }
+ }
+ }
+ }
+
+ define_feature!(1, DataLossProtect, [InitContext, NodeContext],
+ "Feature flags for `option_data_loss_protect`.", set_data_loss_protect_optional,
+ set_data_loss_protect_required, supports_data_loss_protect, requires_data_loss_protect);
+ // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
+ define_feature!(3, InitialRoutingSync, [InitContext], "Feature flags for `initial_routing_sync`.",
+ set_initial_routing_sync_optional, set_initial_routing_sync_required,
+ initial_routing_sync);
+ define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
+ "Feature flags for `option_upfront_shutdown_script`.", set_upfront_shutdown_script_optional,
+ set_upfront_shutdown_script_required, supports_upfront_shutdown_script,
+ requires_upfront_shutdown_script);
+ define_feature!(7, GossipQueries, [InitContext, NodeContext],
+ "Feature flags for `gossip_queries`.", set_gossip_queries_optional, set_gossip_queries_required,
+ supports_gossip_queries, requires_gossip_queries);
+ define_feature!(9, VariableLengthOnion, [InitContext, NodeContext, InvoiceContext],
+ "Feature flags for `var_onion_optin`.", set_variable_length_onion_optional,
+ set_variable_length_onion_required, supports_variable_length_onion,
+ requires_variable_length_onion);
+ define_feature!(13, StaticRemoteKey, [InitContext, NodeContext, ChannelTypeContext],
+ "Feature flags for `option_static_remotekey`.", set_static_remote_key_optional,
+ set_static_remote_key_required, supports_static_remote_key, requires_static_remote_key);
+ define_feature!(15, PaymentSecret, [InitContext, NodeContext, InvoiceContext],
+ "Feature flags for `payment_secret`.", set_payment_secret_optional, set_payment_secret_required,
+ supports_payment_secret, requires_payment_secret);
+ define_feature!(17, BasicMPP, [InitContext, NodeContext, InvoiceContext],
+ "Feature flags for `basic_mpp`.", set_basic_mpp_optional, set_basic_mpp_required,
+ supports_basic_mpp, requires_basic_mpp);
+ define_feature!(27, ShutdownAnySegwit, [InitContext, NodeContext],
+ "Feature flags for `opt_shutdown_anysegwit`.", set_shutdown_any_segwit_optional,
+ set_shutdown_any_segwit_required, supports_shutdown_anysegwit, requires_shutdown_anysegwit);
+ define_feature!(45, ChannelType, [InitContext, NodeContext],
+ "Feature flags for `option_channel_type`.", set_channel_type_optional,
+ set_channel_type_required, supports_channel_type, requires_channel_type);
+ define_feature!(55, Keysend, [NodeContext],
+ "Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
+ supports_keysend, requires_keysend);
+
+ #[cfg(test)]
+ define_feature!(123456789, UnknownFeature, [NodeContext, ChannelContext, InvoiceContext],
+ "Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
+ set_unknown_feature_required, supports_unknown_test_feature, requires_unknown_test_feature);