Sanity check that known features are not required

diff --git a/lightning/src/ln/features.rs b/lightning/src/ln/features.rs
index 613d2db14590b5115b9ae6c18461699141dd0c19..b65b9b1b245e0a8922a4b69a8dbebfe2f76a500e 100644 (file)
--- a/lightning/src/ln/features.rs
+++ b/lightning/src/ln/features.rs
@@ -166,6 +166,13 @@ mod sealed {
                                /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
                                const OPTIONAL_MASK: u8 = 1 << (Self::ODD_BIT - 8 * Self::BYTE_OFFSET);
 
+                               /// Returns whether the feature is required by the given flags.
+                               #[inline]
+                               fn requires_feature(flags: &Vec<u8>) -> bool {
+                                       flags.len() > Self::BYTE_OFFSET &&
+                                               (flags[Self::BYTE_OFFSET] & Self::REQUIRED_MASK) != 0
+                               }
+
                                /// Returns whether the feature is supported by the given flags.
                                #[inline]
                                fn supports_feature(flags: &Vec<u8>) -> bool {
@@ -429,12 +436,20 @@ impl<T: sealed::Context> Features<T> {
 }
 
 impl<T: sealed::DataLossProtect> Features<T> {
+       #[cfg(test)]
+       pub(crate) fn requires_data_loss_protect(&self) -> bool {
+               <T as sealed::DataLossProtect>::requires_feature(&self.flags)
+       }
        pub(crate) fn supports_data_loss_protect(&self) -> bool {
                <T as sealed::DataLossProtect>::supports_feature(&self.flags)
        }
 }
 
 impl<T: sealed::UpfrontShutdownScript> Features<T> {
+       #[cfg(test)]
+       pub(crate) fn requires_upfront_shutdown_script(&self) -> bool {
+               <T as sealed::UpfrontShutdownScript>::requires_feature(&self.flags)
+       }
        pub(crate) fn supports_upfront_shutdown_script(&self) -> bool {
                <T as sealed::UpfrontShutdownScript>::supports_feature(&self.flags)
        }
@@ -446,6 +461,10 @@ impl<T: sealed::UpfrontShutdownScript> Features<T> {
 }
 
 impl<T: sealed::VariableLengthOnion> Features<T> {
+       #[cfg(test)]
+       pub(crate) fn requires_variable_length_onion(&self) -> bool {
+               <T as sealed::VariableLengthOnion>::requires_feature(&self.flags)
+       }
        pub(crate) fn supports_variable_length_onion(&self) -> bool {
                <T as sealed::VariableLengthOnion>::supports_feature(&self.flags)
        }
@@ -461,16 +480,24 @@ impl<T: sealed::InitialRoutingSync> Features<T> {
 }
 
 impl<T: sealed::PaymentSecret> Features<T> {
-       #[allow(dead_code)]
+       #[cfg(test)]
+       pub(crate) fn requires_payment_secret(&self) -> bool {
+               <T as sealed::PaymentSecret>::requires_feature(&self.flags)
+       }
        // Note that we never need to test this since what really matters is the invoice - iff the
        // invoice provides a payment_secret, we assume that we can use it (ie that the recipient
        // supports payment_secret).
+       #[allow(dead_code)]
        pub(crate) fn supports_payment_secret(&self) -> bool {
                <T as sealed::PaymentSecret>::supports_feature(&self.flags)
        }
 }
 
 impl<T: sealed::BasicMPP> Features<T> {
+       #[cfg(test)]
+       pub(crate) fn requires_basic_mpp(&self) -> bool {
+               <T as sealed::BasicMPP>::requires_feature(&self.flags)
+       }
        // We currently never test for this since we don't actually *generate* multipath routes.
        #[allow(dead_code)]
        pub(crate) fn supports_basic_mpp(&self) -> bool {
@@ -505,7 +532,7 @@ mod tests {
        use super::{ChannelFeatures, InitFeatures, NodeFeatures};
 
        #[test]
-       fn sanity_test_our_features() {
+       fn sanity_test_known_features() {
                assert!(!ChannelFeatures::known().requires_unknown_bits());
                assert!(!ChannelFeatures::known().supports_unknown_bits());
                assert!(!InitFeatures::known().requires_unknown_bits());
@@ -515,18 +542,28 @@ mod tests {
 
                assert!(InitFeatures::known().supports_upfront_shutdown_script());
                assert!(NodeFeatures::known().supports_upfront_shutdown_script());
+               assert!(!InitFeatures::known().requires_upfront_shutdown_script());
+               assert!(!NodeFeatures::known().requires_upfront_shutdown_script());
 
                assert!(InitFeatures::known().supports_data_loss_protect());
                assert!(NodeFeatures::known().supports_data_loss_protect());
+               assert!(!InitFeatures::known().requires_data_loss_protect());
+               assert!(!NodeFeatures::known().requires_data_loss_protect());
 
                assert!(InitFeatures::known().supports_variable_length_onion());
                assert!(NodeFeatures::known().supports_variable_length_onion());
+               assert!(!InitFeatures::known().requires_variable_length_onion());
+               assert!(!NodeFeatures::known().requires_variable_length_onion());
 
                assert!(InitFeatures::known().supports_payment_secret());
                assert!(NodeFeatures::known().supports_payment_secret());
+               assert!(!InitFeatures::known().requires_payment_secret());
+               assert!(!NodeFeatures::known().requires_payment_secret());
 
                assert!(InitFeatures::known().supports_basic_mpp());
                assert!(NodeFeatures::known().supports_basic_mpp());
+               assert!(!InitFeatures::known().requires_basic_mpp());
+               assert!(!NodeFeatures::known().requires_basic_mpp());
 
                let mut init_features = InitFeatures::known();
                assert!(init_features.initial_routing_sync());