Remove unnecessary feature test-only methods
[rust-lightning] / lightning / src / ln / features.rs
index fc2526fe55842bf41022cd67d88fba50a34aa672..a9f5a10ee2dad14395e18eda253cbaba2943106c 100644 (file)
@@ -1,10 +1,18 @@
+// This file is Copyright its original authors, visible in version control
+// history.
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
 //! Feature flag definitions for the Lightning protocol according to [BOLT #9].
 //!
 //! Lightning nodes advertise a supported set of operation through feature flags. Features are
 //! applicable for a specific context as indicated in some [messages]. [`Features`] encapsulates
 //! behavior for specifying and checking feature flags for a particular context. Each feature is
-//! defined internally by a trait specifying the corresponding flags (i.e., even and odd bits). A
-//! [`Context`] is used to parameterize [`Features`] and defines which features it can support.
+//! defined internally by a trait specifying the corresponding flags (i.e., even and odd bits).
 //!
 //! Whether a feature is considered "known" or "unknown" is relative to the implementation, whereas
 //! the term "supports" is used in reference to a particular set of [`Features`]. That is, a node
 //! And the implementation can interpret a feature if the feature is known to it.
 //!
 //! [BOLT #9]: https://github.com/lightningnetwork/lightning-rfc/blob/master/09-features.md
-//! [messages]: ../msgs/index.html
-//! [`Features`]: struct.Features.html
-//! [`Context`]: sealed/trait.Context.html
+//! [messages]: crate::ln::msgs
 
-use std::{cmp, fmt};
-use std::result::Result;
-use std::marker::PhantomData;
+use prelude::*;
+use core::{cmp, fmt};
+use core::marker::PhantomData;
 
+use bitcoin::bech32;
+use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5, WriteBase32};
 use ln::msgs::DecodeError;
 use util::ser::{Readable, Writeable, Writer};
 
 mod sealed {
+       use prelude::*;
+       use ln::features::Features;
+
        /// The context in which [`Features`] are applicable. Defines which features are required and
        /// which are optional for the context.
-       ///
-       /// [`Features`]: ../struct.Features.html
        pub trait Context {
                /// Features that are known to the implementation, where a required feature is indicated by
                /// its even bit and an optional feature is indicated by its odd bit.
@@ -41,13 +50,12 @@ mod sealed {
        /// Defines a [`Context`] by stating which features it requires and which are optional. Features
        /// are specified as a comma-separated list of bytes where each byte is a pipe-delimited list of
        /// feature identifiers.
-       ///
-       /// [`Context`]: trait.Context.html
        macro_rules! define_context {
                ($context: ident {
                        required_features: [$( $( $required_feature: ident )|*, )*],
                        optional_features: [$( $( $optional_feature: ident )|*, )*],
                }) => {
+                       #[derive(Eq, PartialEq)]
                        pub struct $context {}
 
                        impl Context for $context {
@@ -89,17 +97,21 @@ mod sealed {
                        // Byte 0
                        ,
                        // Byte 1
-                       ,
+                       VariableLengthOnion | StaticRemoteKey | PaymentSecret,
                        // Byte 2
                        ,
+                       // Byte 3
+                       ,
                ],
                optional_features: [
                        // Byte 0
-                       DataLossProtect | InitialRoutingSync | UpfrontShutdownScript,
+                       DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
                        // Byte 1
-                       VariableLengthOnion | PaymentSecret,
+                       ,
                        // Byte 2
                        BasicMPP,
+                       // Byte 3
+                       ShutdownAnySegwit,
                ],
        });
        define_context!(NodeContext {
@@ -107,30 +119,51 @@ mod sealed {
                        // Byte 0
                        ,
                        // Byte 1
-                       ,
+                       VariableLengthOnion | StaticRemoteKey | PaymentSecret,
                        // Byte 2
                        ,
+                       // Byte 3
+                       ,
                ],
                optional_features: [
                        // Byte 0
-                       DataLossProtect | UpfrontShutdownScript,
+                       DataLossProtect | UpfrontShutdownScript | GossipQueries,
                        // Byte 1
-                       VariableLengthOnion | PaymentSecret,
+                       ,
                        // Byte 2
                        BasicMPP,
+                       // Byte 3
+                       ShutdownAnySegwit,
                ],
        });
        define_context!(ChannelContext {
                required_features: [],
                optional_features: [],
        });
+       define_context!(InvoiceContext {
+               required_features: [
+                       // Byte 0
+                       ,
+                       // Byte 1
+                       VariableLengthOnion | PaymentSecret,
+                       // Byte 2
+                       ,
+               ],
+               optional_features: [
+                       // Byte 0
+                       ,
+                       // Byte 1
+                       ,
+                       // Byte 2
+                       BasicMPP,
+               ],
+       });
 
        /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
        /// useful for manipulating feature flags.
-       ///
-       /// [`Context`]: trait.Context.html
        macro_rules! define_feature {
-               ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr) => {
+               ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
+                $required_setter: ident) => {
                        #[doc = $doc]
                        ///
                        /// See [BOLT #9] for details.
@@ -166,6 +199,13 @@ 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 {
@@ -173,6 +213,16 @@ mod sealed {
                                                (flags[Self::BYTE_OFFSET] & (Self::REQUIRED_MASK | Self::OPTIONAL_MASK)) != 0
                                }
 
+                               /// Sets the feature's required (even) bit in the given flags.
+                               #[inline]
+                               fn set_required_bit(flags: &mut Vec<u8>) {
+                                       if flags.len() <= Self::BYTE_OFFSET {
+                                               flags.resize(Self::BYTE_OFFSET + 1, 0u8);
+                                       }
+
+                                       flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
+                               }
+
                                /// Sets the feature's optional (odd) bit in the given flags.
                                #[inline]
                                fn set_optional_bit(flags: &mut Vec<u8>) {
@@ -191,6 +241,24 @@ mod sealed {
                                                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
                                }
                        }
 
@@ -203,26 +271,46 @@ mod sealed {
                                        const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
                                }
                        )*
+
                }
        }
 
        define_feature!(1, DataLossProtect, [InitContext, NodeContext],
-               "Feature flags for `option_data_loss_protect`.");
+               "Feature flags for `option_data_loss_protect`.", set_data_loss_protect_optional,
+               set_data_loss_protect_required);
        // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
-       define_feature!(3, InitialRoutingSync, [InitContext],
-               "Feature flags for `initial_routing_sync`.");
+       define_feature!(3, InitialRoutingSync, [InitContext], "Feature flags for `initial_routing_sync`.",
+               set_initial_routing_sync_optional, set_initial_routing_sync_required);
        define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
-               "Feature flags for `option_upfront_shutdown_script`.");
-       define_feature!(9, VariableLengthOnion, [InitContext, NodeContext],
-               "Feature flags for `var_onion_optin`.");
-       define_feature!(15, PaymentSecret, [InitContext, NodeContext],
-               "Feature flags for `payment_secret`.");
-       define_feature!(17, BasicMPP, [InitContext, NodeContext],
-               "Feature flags for `basic_mpp`.");
+               "Feature flags for `option_upfront_shutdown_script`.", set_upfront_shutdown_script_optional,
+               set_upfront_shutdown_script_required);
+       define_feature!(7, GossipQueries, [InitContext, NodeContext],
+               "Feature flags for `gossip_queries`.", set_gossip_queries_optional, set_gossip_queries_required);
+       define_feature!(9, VariableLengthOnion, [InitContext, NodeContext, InvoiceContext],
+               "Feature flags for `var_onion_optin`.", set_variable_length_onion_optional,
+               set_variable_length_onion_required);
+       define_feature!(13, StaticRemoteKey, [InitContext, NodeContext],
+               "Feature flags for `option_static_remotekey`.", set_static_remote_key_optional,
+               set_static_remote_key_required);
+       define_feature!(15, PaymentSecret, [InitContext, NodeContext, InvoiceContext],
+               "Feature flags for `payment_secret`.", set_payment_secret_optional, set_payment_secret_required);
+       define_feature!(17, BasicMPP, [InitContext, NodeContext, InvoiceContext],
+               "Feature flags for `basic_mpp`.", set_basic_mpp_optional, set_basic_mpp_required);
+       define_feature!(27, ShutdownAnySegwit, [InitContext, NodeContext],
+               "Feature flags for `opt_shutdown_anysegwit`.", set_shutdown_any_segwit_optional,
+               set_shutdown_any_segwit_required);
+
+       #[cfg(test)]
+       define_feature!(123456789, UnknownFeature, [NodeContext, ChannelContext],
+               "Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
+               set_unknown_feature_required);
 }
 
 /// Tracks the set of features which a node implements, templated by the context in which it
 /// appears.
+///
+/// (C-not exported) as we map the concrete feature types below directly instead
+#[derive(Eq)]
 pub struct Features<T: sealed::Context> {
        /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
        flags: Vec<u8>,
@@ -254,6 +342,8 @@ pub type InitFeatures = Features<sealed::InitContext>;
 pub type NodeFeatures = Features<sealed::NodeContext>;
 /// Features used within a `channel_announcement` message.
 pub type ChannelFeatures = Features<sealed::ChannelContext>;
+/// Features used within an invoice.
+pub type InvoiceFeatures = Features<sealed::InvoiceContext>;
 
 impl InitFeatures {
        /// Writes all features present up to, and including, 13.
@@ -282,56 +372,120 @@ impl InitFeatures {
                }
                self
        }
+
+       /// Converts `InitFeatures` to `Features<C>`. Only known `InitFeatures` relevant to context `C`
+       /// are included in the result.
+       pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
+               self.to_context_internal()
+       }
 }
 
-impl ChannelFeatures {
-       /// Takes the flags that we know how to interpret in an init-context features that are also
-       /// relevant in a channel-context features and creates a channel-context features from them.
-       pub(crate) fn with_known_relevant_init_flags(_init_ctx: &InitFeatures) -> Self {
-               // There are currently no channel flags defined that we understand.
-               Self { flags: Vec::new(), mark: PhantomData, }
+impl InvoiceFeatures {
+       /// Converts `InvoiceFeatures` to `Features<C>`. Only known `InvoiceFeatures` relevant to
+       /// context `C` are included in the result.
+       pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
+               self.to_context_internal()
        }
 }
 
-impl NodeFeatures {
-       /// Takes the flags that we know how to interpret in an init-context features that are also
-       /// relevant in a node-context features and creates a node-context features from them.
-       /// Be sure to blank out features that are unknown to us.
-       pub(crate) fn with_known_relevant_init_flags(init_ctx: &InitFeatures) -> Self {
-               use ln::features::sealed::Context;
-               let byte_count = sealed::NodeContext::KNOWN_FEATURE_MASK.len();
+impl ToBase32 for InvoiceFeatures {
+       fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
+               // Explanation for the "4": the normal way to round up when dividing is to add the divisor
+               // minus one before dividing
+               let length_u5s = (self.flags.len() * 8 + 4) / 5 as usize;
+               let mut res_u5s: Vec<u5> = vec![u5::try_from_u8(0).unwrap(); length_u5s];
+               for (byte_idx, byte) in self.flags.iter().enumerate() {
+                       let bit_pos_from_left_0_indexed = byte_idx * 8;
+                       let new_u5_idx = length_u5s - (bit_pos_from_left_0_indexed / 5) as usize - 1;
+                       let new_bit_pos = bit_pos_from_left_0_indexed % 5;
+                       let shifted_chunk_u16 = (*byte as u16) << new_bit_pos;
+                       let curr_u5_as_u8 = res_u5s[new_u5_idx].to_u8();
+                       res_u5s[new_u5_idx] = u5::try_from_u8(curr_u5_as_u8 | ((shifted_chunk_u16 & 0x001f) as u8)).unwrap();
+                       if new_u5_idx > 0 {
+                               let curr_u5_as_u8 = res_u5s[new_u5_idx - 1].to_u8();
+                               res_u5s[new_u5_idx - 1] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 5) & 0x001f) as u8)).unwrap();
+                       }
+                       if new_u5_idx > 1 {
+                               let curr_u5_as_u8 = res_u5s[new_u5_idx - 2].to_u8();
+                               res_u5s[new_u5_idx - 2] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 10) & 0x001f) as u8)).unwrap();
+                       }
+               }
+               // Trim the highest feature bits.
+               while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
+                       res_u5s.remove(0);
+               }
+               writer.write(&res_u5s)
+       }
+}
 
-               let mut flags = Vec::new();
-               for (i, feature_byte) in init_ctx.flags.iter().enumerate() {
-                       if i < byte_count {
-                               flags.push(feature_byte & sealed::NodeContext::KNOWN_FEATURE_MASK[i]);
+impl Base32Len for InvoiceFeatures {
+       fn base32_len(&self) -> usize {
+               self.to_base32().len()
+       }
+}
+
+impl FromBase32 for InvoiceFeatures {
+       type Err = bech32::Error;
+
+       fn from_base32(field_data: &[u5]) -> Result<InvoiceFeatures, bech32::Error> {
+               // Explanation for the "7": the normal way to round up when dividing is to add the divisor
+               // minus one before dividing
+               let length_bytes = (field_data.len() * 5 + 7) / 8 as usize;
+               let mut res_bytes: Vec<u8> = vec![0; length_bytes];
+               for (u5_idx, chunk) in field_data.iter().enumerate() {
+                       let bit_pos_from_right_0_indexed = (field_data.len() - u5_idx - 1) * 5;
+                       let new_byte_idx = (bit_pos_from_right_0_indexed / 8) as usize;
+                       let new_bit_pos = bit_pos_from_right_0_indexed % 8;
+                       let chunk_u16 = chunk.to_u8() as u16;
+                       res_bytes[new_byte_idx] |= ((chunk_u16 << new_bit_pos) & 0xff) as u8;
+                       if new_byte_idx != length_bytes - 1 {
+                               res_bytes[new_byte_idx + 1] |= ((chunk_u16 >> (8-new_bit_pos)) & 0xff) as u8;
                        }
                }
-               Self { flags, mark: PhantomData, }
+               // Trim the highest feature bits.
+               while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
+                       res_bytes.pop();
+               }
+               Ok(InvoiceFeatures::from_le_bytes(res_bytes))
        }
 }
 
 impl<T: sealed::Context> Features<T> {
        /// Create a blank Features with no features set
-       pub fn empty() -> Features<T> {
+       pub fn empty() -> Self {
                Features {
                        flags: Vec::new(),
                        mark: PhantomData,
                }
        }
 
-       /// Creates features known by the implementation as defined by [`T::KNOWN_FEATURE_FLAGS`].
-       ///
-       /// [`T::KNOWN_FEATURE_FLAGS`]: sealed/trait.Context.html#associatedconstant.KNOWN_FEATURE_FLAGS
-       pub fn known() -> Features<T> {
+       /// Creates a Features with the bits set which are known by the implementation
+       pub fn known() -> Self {
                Self {
                        flags: T::KNOWN_FEATURE_FLAGS.to_vec(),
                        mark: PhantomData,
                }
        }
 
-       #[cfg(test)]
-       /// Create a Features given a set of flags, in LE.
+       /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
+       /// included in the result.
+       fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
+               let from_byte_count = T::KNOWN_FEATURE_MASK.len();
+               let to_byte_count = C::KNOWN_FEATURE_MASK.len();
+               let mut flags = Vec::new();
+               for (i, byte) in self.flags.iter().enumerate() {
+                       if i < from_byte_count && i < to_byte_count {
+                               let from_known_features = T::KNOWN_FEATURE_MASK[i];
+                               let to_known_features = C::KNOWN_FEATURE_MASK[i];
+                               flags.push(byte & from_known_features & to_known_features);
+                       }
+               }
+               Features::<C> { flags, mark: PhantomData, }
+       }
+
+       /// Create a Features given a set of flags, in little-endian. This is in reverse byte order from
+       /// most on-the-wire encodings.
+       /// (C-not exported) as we don't support export across multiple T
        pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
                Features {
                        flags,
@@ -346,15 +500,13 @@ impl<T: sealed::Context> Features<T> {
        }
 
        pub(crate) fn requires_unknown_bits(&self) -> bool {
-               use ln::features::sealed::Context;
-               let byte_count = sealed::InitContext::KNOWN_FEATURE_MASK.len();
-
-               // Bitwise AND-ing with all even bits set except for known features will select unknown
-               // required features.
+               // Bitwise AND-ing with all even bits set except for known features will select required
+               // unknown features.
+               let byte_count = T::KNOWN_FEATURE_MASK.len();
                self.flags.iter().enumerate().any(|(i, &byte)| {
                        let required_features = 0b01_01_01_01;
                        let unknown_features = if i < byte_count {
-                               !sealed::InitContext::KNOWN_FEATURE_MASK[i]
+                               !T::KNOWN_FEATURE_MASK[i]
                        } else {
                                0b11_11_11_11
                        };
@@ -363,14 +515,12 @@ impl<T: sealed::Context> Features<T> {
        }
 
        pub(crate) fn supports_unknown_bits(&self) -> bool {
-               use ln::features::sealed::Context;
-               let byte_count = sealed::InitContext::KNOWN_FEATURE_MASK.len();
-
                // Bitwise AND-ing with all even and odd bits set except for known features will select
-               // unknown features.
+               // both required and optional unknown features.
+               let byte_count = T::KNOWN_FEATURE_MASK.len();
                self.flags.iter().enumerate().any(|(i, &byte)| {
                        let unknown_features = if i < byte_count {
-                               !sealed::InitContext::KNOWN_FEATURE_MASK[i]
+                               !T::KNOWN_FEATURE_MASK[i]
                        } else {
                                0b11_11_11_11
                        };
@@ -383,77 +533,115 @@ impl<T: sealed::Context> Features<T> {
        pub(crate) fn byte_count(&self) -> usize {
                self.flags.len()
        }
-
-       #[cfg(test)]
-       pub(crate) fn set_require_unknown_bits(&mut self) {
-               let newlen = cmp::max(3, self.flags.len());
-               self.flags.resize(newlen, 0u8);
-               self.flags[2] |= 0x40;
-       }
-
-       #[cfg(test)]
-       pub(crate) fn clear_require_unknown_bits(&mut self) {
-               let newlen = cmp::max(3, self.flags.len());
-               self.flags.resize(newlen, 0u8);
-               self.flags[2] &= !0x40;
-               if self.flags.len() == 3 && self.flags[2] == 0 {
-                       self.flags.resize(2, 0u8);
-               }
-               if self.flags.len() == 2 && self.flags[1] == 0 {
-                       self.flags.resize(1, 0u8);
-               }
-       }
 }
 
 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)
        }
        #[cfg(test)]
-       pub(crate) fn unset_upfront_shutdown_script(&mut self) {
-               <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags)
+       pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
+               <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
+               self
+       }
+}
+
+
+impl<T: sealed::GossipQueries> Features<T> {
+       #[cfg(test)]
+       pub(crate) fn requires_gossip_queries(&self) -> bool {
+               <T as sealed::GossipQueries>::requires_feature(&self.flags)
+       }
+       pub(crate) fn supports_gossip_queries(&self) -> bool {
+               <T as sealed::GossipQueries>::supports_feature(&self.flags)
+       }
+       #[cfg(test)]
+       pub(crate) fn clear_gossip_queries(mut self) -> Self {
+               <T as sealed::GossipQueries>::clear_bits(&mut self.flags);
+               self
        }
 }
 
 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)
        }
 }
 
+impl<T: sealed::StaticRemoteKey> Features<T> {
+       pub(crate) fn supports_static_remote_key(&self) -> bool {
+               <T as sealed::StaticRemoteKey>::supports_feature(&self.flags)
+       }
+       #[cfg(test)]
+       pub(crate) fn requires_static_remote_key(&self) -> bool {
+               <T as sealed::StaticRemoteKey>::requires_feature(&self.flags)
+       }
+}
+
 impl<T: sealed::InitialRoutingSync> Features<T> {
        pub(crate) fn initial_routing_sync(&self) -> bool {
                <T as sealed::InitialRoutingSync>::supports_feature(&self.flags)
        }
+       // We are no longer setting initial_routing_sync now that gossip_queries
+       // is enabled. This feature is ignored by a peer when gossip_queries has 
+       // been negotiated.
+       #[cfg(test)]
        pub(crate) fn clear_initial_routing_sync(&mut self) {
                <T as sealed::InitialRoutingSync>::clear_bits(&mut self.flags)
        }
 }
 
 impl<T: sealed::PaymentSecret> Features<T> {
-       #[allow(dead_code)]
-       // 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).
-       pub(crate) fn supports_payment_secret(&self) -> bool {
+       #[cfg(test)]
+       pub(crate) fn requires_payment_secret(&self) -> bool {
+               <T as sealed::PaymentSecret>::requires_feature(&self.flags)
+       }
+       /// Returns whether the `payment_secret` feature is supported.
+       pub 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 {
                <T as sealed::BasicMPP>::supports_feature(&self.flags)
        }
 }
 
+impl<T: sealed::ShutdownAnySegwit> Features<T> {
+       pub(crate) fn supports_shutdown_anysegwit(&self) -> bool {
+               <T as sealed::ShutdownAnySegwit>::supports_feature(&self.flags)
+       }
+       #[cfg(test)]
+       pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
+               <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
+               self
+       }
+}
+
 impl<T: sealed::Context> Writeable for Features<T> {
        fn write<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
                w.size_hint(self.flags.len() + 2);
@@ -478,10 +666,11 @@ impl<T: sealed::Context> Readable for Features<T> {
 
 #[cfg(test)]
 mod tests {
-       use super::{ChannelFeatures, InitFeatures, NodeFeatures, Features};
+       use super::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
+       use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
 
        #[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());
@@ -491,18 +680,47 @@ 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_gossip_queries());
+               assert!(NodeFeatures::known().supports_gossip_queries());
+               assert!(!InitFeatures::known().requires_gossip_queries());
+               assert!(!NodeFeatures::known().requires_gossip_queries());
 
                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!(InvoiceFeatures::known().supports_variable_length_onion());
+               assert!(InitFeatures::known().requires_variable_length_onion());
+               assert!(NodeFeatures::known().requires_variable_length_onion());
+               assert!(InvoiceFeatures::known().requires_variable_length_onion());
+
+               assert!(InitFeatures::known().supports_static_remote_key());
+               assert!(NodeFeatures::known().supports_static_remote_key());
+               assert!(InitFeatures::known().requires_static_remote_key());
+               assert!(NodeFeatures::known().requires_static_remote_key());
 
                assert!(InitFeatures::known().supports_payment_secret());
                assert!(NodeFeatures::known().supports_payment_secret());
+               assert!(InvoiceFeatures::known().supports_payment_secret());
+               assert!(InitFeatures::known().requires_payment_secret());
+               assert!(NodeFeatures::known().requires_payment_secret());
+               assert!(InvoiceFeatures::known().requires_payment_secret());
 
                assert!(InitFeatures::known().supports_basic_mpp());
                assert!(NodeFeatures::known().supports_basic_mpp());
+               assert!(InvoiceFeatures::known().supports_basic_mpp());
+               assert!(!InitFeatures::known().requires_basic_mpp());
+               assert!(!NodeFeatures::known().requires_basic_mpp());
+               assert!(!InvoiceFeatures::known().requires_basic_mpp());
+
+               assert!(InitFeatures::known().supports_shutdown_anysegwit());
+               assert!(NodeFeatures::known().supports_shutdown_anysegwit());
 
                let mut init_features = InitFeatures::known();
                assert!(init_features.initial_routing_sync());
@@ -511,35 +729,90 @@ mod tests {
        }
 
        #[test]
-       fn sanity_test_unkown_bits_testing() {
-               let mut features = ChannelFeatures::known();
-               features.set_require_unknown_bits();
+       fn sanity_test_unknown_bits() {
+               let features = ChannelFeatures::empty();
+               assert!(!features.requires_unknown_bits());
+               assert!(!features.supports_unknown_bits());
+
+               let features = ChannelFeatures::empty().set_unknown_feature_required();
                assert!(features.requires_unknown_bits());
-               features.clear_require_unknown_bits();
+               assert!(features.supports_unknown_bits());
+
+               let features = ChannelFeatures::empty().set_unknown_feature_optional();
                assert!(!features.requires_unknown_bits());
+               assert!(features.supports_unknown_bits());
        }
 
        #[test]
-       fn test_node_with_known_relevant_init_flags() {
-               // Create an InitFeatures with initial_routing_sync supported.
-               let init_features = InitFeatures::known();
+       fn convert_to_context_with_relevant_flags() {
+               let init_features = InitFeatures::known().clear_upfront_shutdown_script().clear_gossip_queries();
                assert!(init_features.initial_routing_sync());
+               assert!(!init_features.supports_upfront_shutdown_script());
+               assert!(!init_features.supports_gossip_queries());
 
-               // Attempt to pull out non-node-context feature flags from these InitFeatures.
-               let res = NodeFeatures::with_known_relevant_init_flags(&init_features);
-
+               let node_features: NodeFeatures = init_features.to_context();
                {
-                       // Check that the flags are as expected: optional_data_loss_protect,
-                       // option_upfront_shutdown_script, var_onion_optin, payment_secret, and
-                       // basic_mpp.
-                       assert_eq!(res.flags.len(), 3);
-                       assert_eq!(res.flags[0], 0b00100010);
-                       assert_eq!(res.flags[1], 0b10000010);
-                       assert_eq!(res.flags[2], 0b00000010);
+                       // Check that the flags are as expected:
+                       // - option_data_loss_protect
+                       // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
+                       // - basic_mpp
+                       // - opt_shutdown_anysegwit
+                       assert_eq!(node_features.flags.len(), 4);
+                       assert_eq!(node_features.flags[0], 0b00000010);
+                       assert_eq!(node_features.flags[1], 0b01010001);
+                       assert_eq!(node_features.flags[2], 0b00000010);
+                       assert_eq!(node_features.flags[3], 0b00001000);
                }
 
-               // Check that the initial_routing_sync feature was correctly blanked out.
-               let new_features: InitFeatures = Features::from_le_bytes(res.flags);
-               assert!(!new_features.initial_routing_sync());
+               // Check that cleared flags are kept blank when converting back:
+               // - initial_routing_sync was not applicable to NodeContext
+               // - upfront_shutdown_script was cleared before converting
+               // - gossip_queries was cleared before converting
+               let features: InitFeatures = node_features.to_context_internal();
+               assert!(!features.initial_routing_sync());
+               assert!(!features.supports_upfront_shutdown_script());
+               assert!(!init_features.supports_gossip_queries());
+       }
+
+       #[test]
+       fn set_feature_bits() {
+               let features = InvoiceFeatures::empty()
+                       .set_basic_mpp_optional()
+                       .set_payment_secret_required();
+               assert!(features.supports_basic_mpp());
+               assert!(!features.requires_basic_mpp());
+               assert!(features.requires_payment_secret());
+               assert!(features.supports_payment_secret());
+       }
+
+       #[test]
+       fn invoice_features_encoding() {
+               let features_as_u5s = vec![
+                       u5::try_from_u8(6).unwrap(),
+                       u5::try_from_u8(10).unwrap(),
+                       u5::try_from_u8(25).unwrap(),
+                       u5::try_from_u8(1).unwrap(),
+                       u5::try_from_u8(10).unwrap(),
+                       u5::try_from_u8(0).unwrap(),
+                       u5::try_from_u8(20).unwrap(),
+                       u5::try_from_u8(2).unwrap(),
+                       u5::try_from_u8(0).unwrap(),
+                       u5::try_from_u8(6).unwrap(),
+                       u5::try_from_u8(0).unwrap(),
+                       u5::try_from_u8(16).unwrap(),
+                       u5::try_from_u8(1).unwrap(),
+               ];
+               let features = InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
+
+               // Test length calculation.
+               assert_eq!(features.base32_len(), 13);
+
+               // Test serialization.
+               let features_serialized = features.to_base32();
+               assert_eq!(features_as_u5s, features_serialized);
+
+               // Test deserialization.
+               let features_deserialized = InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
+               assert_eq!(features, features_deserialized);
        }
 }