Merge pull request #2726 from shaavan/issue2712
[rust-lightning] / lightning / src / onion_message / messenger.rs
index 626e2b05840343394afa87816d4e9434a6b653ff..cf0f9e086b5c41a12c2e9b1b5e27f3a03949fae7 100644 (file)
@@ -19,11 +19,14 @@ use crate::blinded_path::BlindedPath;
 use crate::blinded_path::message::{advance_path_by_one, ForwardTlvs, ReceiveTlvs};
 use crate::blinded_path::utils;
 use crate::sign::{EntropySource, KeysManager, NodeSigner, Recipient};
+#[cfg(not(c_bindings))]
+use crate::ln::channelmanager::{SimpleArcChannelManager, SimpleRefChannelManager};
 use crate::ln::features::{InitFeatures, NodeFeatures};
 use crate::ln::msgs::{self, OnionMessage, OnionMessageHandler};
 use crate::ln::onion_utils;
 use crate::ln::peer_handler::IgnoringMessageHandler;
-pub use super::packet::{CustomOnionMessageContents, OnionMessageContents};
+pub use super::packet::OnionMessageContents;
+use super::packet::ParsedOnionMessageContents;
 use super::offers::OffersMessageHandler;
 use super::packet::{BIG_PACKET_HOP_DATA_LEN, ForwardControlTlvs, Packet, Payload, ReceiveControlTlvs, SMALL_PACKET_HOP_DATA_LEN};
 use crate::util::logger::Logger;
@@ -60,7 +63,7 @@ use crate::prelude::*;
 /// # use lightning::blinded_path::BlindedPath;
 /// # use lightning::sign::KeysManager;
 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
-/// # use lightning::onion_message::{CustomOnionMessageContents, Destination, MessageRouter, OnionMessageContents, OnionMessagePath, OnionMessenger};
+/// # use lightning::onion_message::{OnionMessageContents, Destination, MessageRouter, OnionMessagePath, OnionMessenger};
 /// # use lightning::util::logger::{Logger, Record};
 /// # use lightning::util::ser::{Writeable, Writer};
 /// # use lightning::io;
@@ -101,7 +104,7 @@ use crate::prelude::*;
 ///            // Write your custom onion message to `w`
 ///    }
 /// }
-/// impl CustomOnionMessageContents for YourCustomMessage {
+/// impl OnionMessageContents for YourCustomMessage {
 ///    fn tlv_type(&self) -> u64 {
 ///            # let your_custom_message_type = 42;
 ///            your_custom_message_type
@@ -113,8 +116,7 @@ use crate::prelude::*;
 ///    destination: Destination::Node(destination_node_id),
 /// };
 /// let reply_path = None;
-/// # let your_custom_message = YourCustomMessage {};
-/// let message = OnionMessageContents::Custom(your_custom_message);
+/// # let message = YourCustomMessage {};
 /// onion_messenger.send_onion_message(path, message, reply_path);
 ///
 /// // Create a blinded path to yourself, for someone to send an onion message to.
@@ -128,8 +130,7 @@ use crate::prelude::*;
 ///    destination: Destination::BlindedPath(blinded_path),
 /// };
 /// let reply_path = None;
-/// # let your_custom_message = YourCustomMessage {};
-/// let message = OnionMessageContents::Custom(your_custom_message);
+/// # let message = YourCustomMessage {};
 /// onion_messenger.send_onion_message(path, message, reply_path);
 /// ```
 ///
@@ -154,6 +155,38 @@ where
        custom_handler: CMH,
 }
 
+/// An [`OnionMessage`] for [`OnionMessenger`] to send.
+///
+/// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
+/// enqueued for sending.
+#[cfg(not(c_bindings))]
+pub struct PendingOnionMessage<T: OnionMessageContents> {
+       /// The message contents to send in an [`OnionMessage`].
+       pub contents: T,
+
+       /// The destination of the message.
+       pub destination: Destination,
+
+       /// A reply path to include in the [`OnionMessage`] for a response.
+       pub reply_path: Option<BlindedPath>,
+}
+
+#[cfg(c_bindings)]
+/// An [`OnionMessage`] for [`OnionMessenger`] to send.
+///
+/// These are obtained when released from [`OnionMessenger`]'s handlers after which they are
+/// enqueued for sending.
+pub type PendingOnionMessage<T: OnionMessageContents> = (T, Destination, Option<BlindedPath>);
+
+pub(crate) fn new_pending_onion_message<T: OnionMessageContents>(
+       contents: T, destination: Destination, reply_path: Option<BlindedPath>
+) -> PendingOnionMessage<T> {
+       #[cfg(not(c_bindings))]
+       return PendingOnionMessage { contents, destination, reply_path };
+       #[cfg(c_bindings)]
+       return (contents, destination, reply_path);
+}
+
 /// A trait defining behavior for routing an [`OnionMessage`].
 pub trait MessageRouter {
        /// Returns a route for sending an [`OnionMessage`] to the given [`Destination`].
@@ -162,14 +195,18 @@ pub trait MessageRouter {
        ) -> Result<OnionMessagePath, ()>;
 }
 
-/// A [`MessageRouter`] that always fails.
+/// A [`MessageRouter`] that can only route to a directly connected [`Destination`].
 pub struct DefaultMessageRouter;
 
 impl MessageRouter for DefaultMessageRouter {
        fn find_path(
-               &self, _sender: PublicKey, _peers: Vec<PublicKey>, _destination: Destination
+               &self, _sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
        ) -> Result<OnionMessagePath, ()> {
-               Err(())
+               if peers.contains(&destination.first_node()) {
+                       Ok(OnionMessagePath { intermediate_nodes: vec![], destination })
+               } else {
+                       Err(())
+               }
        }
 }
 
@@ -199,6 +236,13 @@ impl Destination {
                        Destination::BlindedPath(BlindedPath { blinded_hops, .. }) => blinded_hops.len(),
                }
        }
+
+       fn first_node(&self) -> PublicKey {
+               match self {
+                       Destination::Node(node_id) => *node_id,
+                       Destination::BlindedPath(BlindedPath { introduction_node_id: node_id, .. }) => *node_id,
+               }
+       }
 }
 
 /// Errors that may occur when [sending an onion message].
@@ -211,8 +255,8 @@ pub enum SendError {
        /// Because implementations such as Eclair will drop onion messages where the message packet
        /// exceeds 32834 bytes, we refuse to send messages where the packet exceeds this size.
        TooBigPacket,
-       /// The provided [`Destination`] was an invalid [`BlindedPath`], due to having fewer than two
-       /// blinded hops.
+       /// The provided [`Destination`] was an invalid [`BlindedPath`] due to not having any blinded
+       /// hops.
        TooFewBlindedHops,
        /// Our next-hop peer was offline or does not support onion message forwarding.
        InvalidFirstHop,
@@ -244,32 +288,48 @@ pub enum SendError {
 pub trait CustomOnionMessageHandler {
        /// The message known to the handler. To support multiple message types, you may want to make this
        /// an enum with a variant for each supported message.
-       type CustomMessage: CustomOnionMessageContents;
+       type CustomMessage: OnionMessageContents;
 
        /// Called with the custom message that was received, returning a response to send, if any.
+       ///
+       /// The returned [`Self::CustomMessage`], if any, is enqueued to be sent by [`OnionMessenger`].
        fn handle_custom_message(&self, msg: Self::CustomMessage) -> Option<Self::CustomMessage>;
 
        /// Read a custom message of type `message_type` from `buffer`, returning `Ok(None)` if the
        /// message type is unknown.
        fn read_custom_message<R: io::Read>(&self, message_type: u64, buffer: &mut R) -> Result<Option<Self::CustomMessage>, msgs::DecodeError>;
+
+       /// Releases any [`Self::CustomMessage`]s that need to be sent.
+       ///
+       /// Typically, this is used for messages initiating a message flow rather than in response to
+       /// another message. The latter should use the return value of [`Self::handle_custom_message`].
+       #[cfg(not(c_bindings))]
+       fn release_pending_custom_messages(&self) -> Vec<PendingOnionMessage<Self::CustomMessage>>;
+
+       /// Releases any [`Self::CustomMessage`]s that need to be sent.
+       ///
+       /// Typically, this is used for messages initiating a message flow rather than in response to
+       /// another message. The latter should use the return value of [`Self::handle_custom_message`].
+       #[cfg(c_bindings)]
+       fn release_pending_custom_messages(&self) -> Vec<(Self::CustomMessage, Destination, Option<BlindedPath>)>;
 }
 
 /// A processed incoming onion message, containing either a Forward (another onion message)
 /// or a Receive payload with decrypted contents.
-pub enum PeeledOnion<CM: CustomOnionMessageContents> {
+pub enum PeeledOnion<T: OnionMessageContents> {
        /// Forwarded onion, with the next node id and a new onion
        Forward(PublicKey, OnionMessage),
        /// Received onion message, with decrypted contents, path_id, and reply path
-       Receive(OnionMessageContents<CM>, Option<[u8; 32]>, Option<BlindedPath>)
+       Receive(ParsedOnionMessageContents<T>, Option<[u8; 32]>, Option<BlindedPath>)
 }
 
 /// Creates an [`OnionMessage`] with the given `contents` for sending to the destination of
 /// `path`.
 ///
 /// Returns both the node id of the peer to send the message to and the message itself.
-pub fn create_onion_message<ES: Deref, NS: Deref, T: CustomOnionMessageContents>(
+pub fn create_onion_message<ES: Deref, NS: Deref, T: OnionMessageContents>(
        entropy_source: &ES, node_signer: &NS, secp_ctx: &Secp256k1<secp256k1::All>,
-       path: OnionMessagePath, contents: OnionMessageContents<T>, reply_path: Option<BlindedPath>,
+       path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
 ) -> Result<(PublicKey, OnionMessage), SendError>
 where
        ES::Target: EntropySource,
@@ -277,7 +337,7 @@ where
 {
        let OnionMessagePath { intermediate_nodes, mut destination } = path;
        if let Destination::BlindedPath(BlindedPath { ref blinded_hops, .. }) = destination {
-               if blinded_hops.len() < 2 {
+               if blinded_hops.is_empty() {
                        return Err(SendError::TooFewBlindedHops);
                }
        }
@@ -322,11 +382,13 @@ where
        }))
 }
 
-/// Decode one layer of an incoming onion message
-/// Returns either a Forward (another onion message), or Receive (decrypted content)
-pub fn peel_onion<NS: Deref, L: Deref, CMH: Deref>(
-       node_signer: NS, secp_ctx: &Secp256k1<secp256k1::All>, logger: L, custom_handler: CMH,
-       msg: &OnionMessage,
+/// Decode one layer of an incoming [`OnionMessage`].
+///
+/// Returns either the next layer of the onion for forwarding or the decrypted content for the
+/// receiver.
+pub fn peel_onion_message<NS: Deref, L: Deref, CMH: Deref>(
+       msg: &OnionMessage, secp_ctx: &Secp256k1<secp256k1::All>, node_signer: NS, logger: L,
+       custom_handler: CMH,
 ) -> Result<PeeledOnion<<<CMH>::Target as CustomOnionMessageHandler>::CustomMessage>, ()>
 where
        NS::Target: NodeSigner,
@@ -360,7 +422,7 @@ where
                onion_decode_ss, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
                (control_tlvs_ss, custom_handler.deref(), logger.deref())
        ) {
-               Ok((Payload::Receive::<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage> {
+               Ok((Payload::Receive::<ParsedOnionMessageContents<<<CMH as Deref>::Target as CustomOnionMessageHandler>::CustomMessage>> {
                        message, control_tlvs: ReceiveControlTlvs::Unblinded(ReceiveTlvs { path_id }), reply_path,
                }, None)) => {
                        Ok(PeeledOnion::Receive(message, path_id, reply_path))
@@ -451,9 +513,8 @@ where
        /// `path`.
        ///
        /// See [`OnionMessenger`] for example usage.
-       pub fn send_onion_message<T: CustomOnionMessageContents>(
-               &self, path: OnionMessagePath, contents: OnionMessageContents<T>,
-               reply_path: Option<BlindedPath>
+       pub fn send_onion_message<T: OnionMessageContents>(
+               &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>
        ) -> Result<(), SendError> {
                let (first_node_id, onion_msg) = create_onion_message(
                        &self.entropy_source, &self.node_signer, &self.secp_ctx, path, contents, reply_path
@@ -470,8 +531,25 @@ where
                }
        }
 
-       fn find_path_and_enqueue_onion_message<T: CustomOnionMessageContents>(
-               &self, contents: OnionMessageContents<T>, destination: Destination,
+       fn handle_onion_message_response<T: OnionMessageContents>(
+               &self, response: Option<T>, reply_path: Option<BlindedPath>, log_suffix: fmt::Arguments
+       ) {
+               if let Some(response) = response {
+                       match reply_path {
+                               Some(reply_path) => {
+                                       self.find_path_and_enqueue_onion_message(
+                                               response, Destination::BlindedPath(reply_path), None, log_suffix
+                                       );
+                               },
+                               None => {
+                                       log_trace!(self.logger, "Missing reply path {}", log_suffix);
+                               },
+                       }
+               }
+       }
+
+       fn find_path_and_enqueue_onion_message<T: OnionMessageContents>(
+               &self, contents: T, destination: Destination, reply_path: Option<BlindedPath>,
                log_suffix: fmt::Arguments
        ) {
                let sender = match self.node_signer.get_node_id(Recipient::Node) {
@@ -493,7 +571,7 @@ where
 
                log_trace!(self.logger, "Sending onion message {}", log_suffix);
 
-               if let Err(e) = self.send_onion_message(path, contents, None) {
+               if let Err(e) = self.send_onion_message(path, contents, reply_path) {
                        log_trace!(self.logger, "Failed sending onion message {}: {:?}", log_suffix, e);
                        return;
                }
@@ -545,44 +623,34 @@ where
        OMH::Target: OffersMessageHandler,
        CMH::Target: CustomOnionMessageHandler,
 {
-       /// Handle an incoming onion message. Currently, if a message was destined for us we will log, but
-       /// soon we'll delegate the onion message to a handler that can generate invoices or send
-       /// payments.
        fn handle_onion_message(&self, _peer_node_id: &PublicKey, msg: &OnionMessage) {
-               match peel_onion(
-                       &*self.node_signer, &self.secp_ctx, &*self.logger, &*self.custom_handler, msg
+               match peel_onion_message(
+                       msg, &self.secp_ctx, &*self.node_signer, &*self.logger, &*self.custom_handler
                ) {
                        Ok(PeeledOnion::Receive(message, path_id, reply_path)) => {
                                log_trace!(self.logger,
                                        "Received an onion message with path_id {:02x?} and {} reply_path",
                                                path_id, if reply_path.is_some() { "a" } else { "no" });
-                               let response = match message {
-                                       OnionMessageContents::Offers(msg) => {
-                                               self.offers_handler.handle_message(msg)
-                                                       .map(|msg| OnionMessageContents::Offers(msg))
-                                       },
-                                       OnionMessageContents::Custom(msg) => {
-                                               self.custom_handler.handle_custom_message(msg)
-                                                       .map(|msg| OnionMessageContents::Custom(msg))
+
+                               match message {
+                                       ParsedOnionMessageContents::Offers(msg) => {
+                                               let response = self.offers_handler.handle_message(msg);
+                                               self.handle_onion_message_response(
+                                                       response, reply_path, format_args!(
+                                                               "when responding to Offers onion message with path_id {:02x?}",
+                                                               path_id
+                                                       )
+                                               );
                                        },
-                               };
-                               if let Some(response) = response {
-                                       match reply_path {
-                                               Some(reply_path) => {
-                                                       self.find_path_and_enqueue_onion_message(
-                                                               response, Destination::BlindedPath(reply_path), format_args!(
-                                                                       "when responding to onion message with path_id {:02x?}", path_id
-                                                               )
-                                                       );
-                                               },
-                                               None => {
-                                                       log_trace!(
-                                                               self.logger,
-                                                               "Missing reply path when responding to onion message with path_id {:02x?}",
+                                       ParsedOnionMessageContents::Custom(msg) => {
+                                               let response = self.custom_handler.handle_custom_message(msg);
+                                               self.handle_onion_message_response(
+                                                       response, reply_path, format_args!(
+                                                               "when responding to Custom onion message with path_id {:02x?}",
                                                                path_id
-                                                       );
-                                               },
-                                       }
+                                                       )
+                                               );
+                                       },
                                }
                        },
                        Ok(PeeledOnion::Forward(next_node_id, onion_message)) => {
@@ -637,7 +705,32 @@ where
                features
        }
 
+       // Before returning any messages to send for the peer, this method will see if any messages were
+       // enqueued in the handler by users, find a path to the corresponding blinded path's introduction
+       // node, and then enqueue the message for sending to the first peer in the full path.
        fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage> {
+               // Enqueue any initiating `OffersMessage`s to send.
+               for message in self.offers_handler.release_pending_messages() {
+                       #[cfg(not(c_bindings))]
+                       let PendingOnionMessage { contents, destination, reply_path } = message;
+                       #[cfg(c_bindings)]
+                       let (contents, destination, reply_path) = message;
+                       self.find_path_and_enqueue_onion_message(
+                               contents, destination, reply_path, format_args!("when sending OffersMessage")
+                       );
+               }
+
+               // Enqueue any initiating `CustomMessage`s to send.
+               for message in self.custom_handler.release_pending_custom_messages() {
+                       #[cfg(not(c_bindings))]
+                       let PendingOnionMessage { contents, destination, reply_path } = message;
+                       #[cfg(c_bindings)]
+                       let (contents, destination, reply_path) = message;
+                       self.find_path_and_enqueue_onion_message(
+                               contents, destination, reply_path, format_args!("when sending CustomMessage")
+                       );
+               }
+
                let mut pending_msgs = self.pending_messages.lock().unwrap();
                if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {
                        return msgs.pop_front()
@@ -651,40 +744,44 @@ where
 /// Useful for simplifying the parameters of [`SimpleArcChannelManager`] and
 /// [`SimpleArcPeerManager`]. See their docs for more details.
 ///
-/// This is not exported to bindings users as `Arc`s don't make sense in bindings.
+/// This is not exported to bindings users as type aliases aren't supported in most languages.
 ///
 /// [`SimpleArcChannelManager`]: crate::ln::channelmanager::SimpleArcChannelManager
 /// [`SimpleArcPeerManager`]: crate::ln::peer_handler::SimpleArcPeerManager
-pub type SimpleArcOnionMessenger<L> = OnionMessenger<
+#[cfg(not(c_bindings))]
+pub type SimpleArcOnionMessenger<M, T, F, L> = OnionMessenger<
        Arc<KeysManager>,
        Arc<KeysManager>,
        Arc<L>,
        Arc<DefaultMessageRouter>,
-       IgnoringMessageHandler,
+       Arc<SimpleArcChannelManager<M, T, F, L>>,
        IgnoringMessageHandler
 >;
 
 /// Useful for simplifying the parameters of [`SimpleRefChannelManager`] and
 /// [`SimpleRefPeerManager`]. See their docs for more details.
 ///
-/// This is not exported to bindings users as general type aliases don't make sense in bindings.
+/// This is not exported to bindings users as type aliases aren't supported in most languages.
 ///
 /// [`SimpleRefChannelManager`]: crate::ln::channelmanager::SimpleRefChannelManager
 /// [`SimpleRefPeerManager`]: crate::ln::peer_handler::SimpleRefPeerManager
-pub type SimpleRefOnionMessenger<'a, 'b, 'c, L> = OnionMessenger<
+#[cfg(not(c_bindings))]
+pub type SimpleRefOnionMessenger<
+       'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, M, T, F, L
+> = OnionMessenger<
        &'a KeysManager,
        &'a KeysManager,
        &'b L,
-       &'c DefaultMessageRouter,
-       IgnoringMessageHandler,
+       &'i DefaultMessageRouter,
+       &'j SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L>,
        IgnoringMessageHandler
 >;
 
 /// Construct onion packet payloads and keys for sending an onion message along the given
 /// `unblinded_path` to the given `destination`.
-fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
-       secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination,
-       message: OnionMessageContents<T>, mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
+fn packet_payloads_and_keys<T: OnionMessageContents, S: secp256k1::Signing + secp256k1::Verification>(
+       secp_ctx: &Secp256k1<S>, unblinded_path: &[PublicKey], destination: Destination, message: T,
+       mut reply_path: Option<BlindedPath>, session_priv: &SecretKey
 ) -> Result<(Vec<(Payload<T>, [u8; 32])>, Vec<onion_utils::OnionKeys>), secp256k1::Error> {
        let num_hops = unblinded_path.len() + destination.num_hops();
        let mut payloads = Vec::with_capacity(num_hops);
@@ -760,7 +857,7 @@ fn packet_payloads_and_keys<T: CustomOnionMessageContents, S: secp256k1::Signing
 }
 
 /// Errors if the serialized payload size exceeds onion_message::BIG_PACKET_HOP_DATA_LEN
-fn construct_onion_message_packet<T: CustomOnionMessageContents>(payloads: Vec<(Payload<T>, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
+fn construct_onion_message_packet<T: OnionMessageContents>(payloads: Vec<(Payload<T>, [u8; 32])>, onion_keys: Vec<onion_utils::OnionKeys>, prng_seed: [u8; 32]) -> Result<Packet, ()> {
        // Spec rationale:
        // "`len` allows larger messages to be sent than the standard 1300 bytes allowed for an HTLC
        // onion, but this should be used sparingly as it is reduces anonymity set, hence the