Implement `Readable` for `Offer`
[rust-lightning] / lightning / src / onion_message / messenger.rs
index b10bd185100ddfcd03a8ced2d68ef9677b1bf667..aa5f658949254fd98dd8de656c11eefba93c56d3 100644 (file)
@@ -16,7 +16,7 @@ use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::secp256k1::{self, PublicKey, Scalar, Secp256k1, SecretKey};
 
 use crate::blinded_path::{BlindedPath, IntroductionNode, NextMessageHop, NodeIdLookUp};
-use crate::blinded_path::message::{advance_path_by_one, ForwardTlvs, ReceiveTlvs};
+use crate::blinded_path::message::{advance_path_by_one, ForwardNode, ForwardTlvs, ReceiveTlvs};
 use crate::blinded_path::utils;
 use crate::events::{Event, EventHandler, EventsProvider};
 use crate::sign::{EntropySource, NodeSigner, Recipient};
@@ -71,6 +71,7 @@ pub(super) const MAX_TIMER_TICKS: usize = 2;
 /// # use bitcoin::hashes::hex::FromHex;
 /// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey, self};
 /// # use lightning::blinded_path::{BlindedPath, EmptyNodeIdLookUp};
+/// # use lightning::blinded_path::message::ForwardNode;
 /// # use lightning::sign::{EntropySource, KeysManager};
 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
 /// # use lightning::onion_message::messenger::{Destination, MessageRouter, OnionMessagePath, OnionMessenger};
@@ -97,7 +98,7 @@ pub(super) const MAX_TIMER_TICKS: usize = 2;
 /// #         })
 /// #     }
 /// #     fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
-/// #         &self, _recipient: PublicKey, _peers: Vec<PublicKey>, _secp_ctx: &Secp256k1<T>
+/// #         &self, _recipient: PublicKey, _peers: Vec<ForwardNode>, _secp_ctx: &Secp256k1<T>
 /// #     ) -> Result<Vec<BlindedPath>, ()> {
 /// #         unreachable!()
 /// #     }
@@ -145,8 +146,11 @@ pub(super) const MAX_TIMER_TICKS: usize = 2;
 ///
 /// // Create a blinded path to yourself, for someone to send an onion message to.
 /// # let your_node_id = hop_node_id1;
-/// let hops = [hop_node_id3, hop_node_id4, your_node_id];
-/// let blinded_path = BlindedPath::new_for_message(&hops, &keys_manager, &secp_ctx).unwrap();
+/// let hops = [
+///    ForwardNode { node_id: hop_node_id3, short_channel_id: None },
+///    ForwardNode { node_id: hop_node_id4, short_channel_id: None },
+/// ];
+/// let blinded_path = BlindedPath::new_for_message(&hops, your_node_id, &keys_manager, &secp_ctx).unwrap();
 ///
 /// // Send a custom onion message to a blinded path.
 /// let destination = Destination::BlindedPath(blinded_path);
@@ -260,14 +264,16 @@ pub struct Responder {
 
 impl Responder {
        /// Creates a new [`Responder`] instance with the provided reply path.
-       fn new(reply_path: BlindedPath, path_id: Option<[u8; 32]>) -> Self {
+       pub(super) fn new(reply_path: BlindedPath, path_id: Option<[u8; 32]>) -> Self {
                Responder {
                        reply_path,
                        path_id,
                }
        }
 
-       /// Creates the appropriate [`ResponseInstruction`] for a given response.
+       /// Creates a [`ResponseInstruction::WithoutReplyPath`] for a given response.
+       ///
+       /// Use when the recipient doesn't need to send back a reply to us.
        pub fn respond<T: OnionMessageContents>(self, response: T) -> ResponseInstruction<T> {
                ResponseInstruction::WithoutReplyPath(OnionMessageResponse {
                        message: response,
@@ -275,6 +281,17 @@ impl Responder {
                        path_id: self.path_id,
                })
        }
+
+       /// Creates a [`ResponseInstruction::WithReplyPath`] for a given response.
+       ///
+       /// Use when the recipient needs to send back a reply to us.
+       pub fn respond_with_reply_path<T: OnionMessageContents>(self, response: T) -> ResponseInstruction<T> {
+               ResponseInstruction::WithReplyPath(OnionMessageResponse {
+                       message: response,
+                       reply_path: self.reply_path,
+                       path_id: self.path_id,
+               })
+       }
 }
 
 /// This struct contains the information needed to reply to a received message.
@@ -286,6 +303,9 @@ pub struct OnionMessageResponse<T: OnionMessageContents> {
 
 /// `ResponseInstruction` represents instructions for responding to received messages.
 pub enum ResponseInstruction<T: OnionMessageContents> {
+       /// Indicates that a response should be sent including a reply path for
+       /// the recipient to respond back.
+       WithReplyPath(OnionMessageResponse<T>),
        /// Indicates that a response should be sent without including a reply path
        /// for the recipient to respond back.
        WithoutReplyPath(OnionMessageResponse<T>),
@@ -337,7 +357,7 @@ pub trait MessageRouter {
        fn create_blinded_paths<
                T: secp256k1::Signing + secp256k1::Verification
        >(
-               &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
+               &self, recipient: PublicKey, peers: Vec<ForwardNode>, secp_ctx: &Secp256k1<T>,
        ) -> Result<Vec<BlindedPath>, ()>;
 }
 
@@ -404,7 +424,7 @@ where
        fn create_blinded_paths<
                T: secp256k1::Signing + secp256k1::Verification
        >(
-               &self, recipient: PublicKey, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
+               &self, recipient: PublicKey, peers: Vec<ForwardNode>, secp_ctx: &Secp256k1<T>,
        ) -> Result<Vec<BlindedPath>, ()> {
                // Limit the number of blinded paths that are computed.
                const MAX_PATHS: usize = 3;
@@ -417,13 +437,13 @@ where
                let is_recipient_announced =
                        network_graph.nodes().contains_key(&NodeId::from_pubkey(&recipient));
 
-               let mut peer_info = peers.iter()
+               let mut peer_info = peers.into_iter()
                        // Limit to peers with announced channels
-                       .filter_map(|pubkey|
+                       .filter_map(|peer|
                                network_graph
-                                       .node(&NodeId::from_pubkey(pubkey))
+                                       .node(&NodeId::from_pubkey(&peer.node_id))
                                        .filter(|info| info.channels.len() >= MIN_PEER_CHANNELS)
-                                       .map(|info| (*pubkey, info.is_tor_only(), info.channels.len()))
+                                       .map(|info| (peer, info.is_tor_only(), info.channels.len()))
                        )
                        // Exclude Tor-only nodes when the recipient is announced.
                        .filter(|(_, is_tor_only, _)| !(*is_tor_only && is_recipient_announced))
@@ -435,12 +455,13 @@ where
                });
 
                let paths = peer_info.into_iter()
-                       .map(|(pubkey, _, _)| vec![pubkey, recipient])
-                       .map(|node_pks| BlindedPath::new_for_message(&node_pks, &*self.entropy_source, secp_ctx))
+                       .map(|(peer, _, _)| {
+                               BlindedPath::new_for_message(&[peer], recipient, &*self.entropy_source, secp_ctx)
+                       })
                        .take(MAX_PATHS)
                        .collect::<Result<Vec<_>, _>>();
 
-               match paths {
+               let mut paths = match paths {
                        Ok(paths) if !paths.is_empty() => Ok(paths),
                        _ => {
                                if is_recipient_announced {
@@ -450,7 +471,12 @@ where
                                        Err(())
                                }
                        },
+               }?;
+               for path in &mut paths {
+                       path.use_compact_introduction_node(&network_graph);
                }
+
+               Ok(paths)
        }
 }
 
@@ -554,7 +580,11 @@ pub enum SendError {
        TooFewBlindedHops,
        /// The first hop is not a peer and doesn't have a known [`SocketAddress`].
        InvalidFirstHop(PublicKey),
-       /// A path from the sender to the destination could not be found by the [`MessageRouter`].
+       /// Indicates that a path could not be found by the [`MessageRouter`].
+       ///
+       /// This occurs when either:
+       /// - No path from the sender to the destination was found to send the onion message
+       /// - No reply path to the sender could be created when responding to an onion message
        PathNotFound,
        /// Onion message contents must have a TLV type >= 64.
        InvalidMessage,
@@ -971,6 +1001,27 @@ where
                        .map_err(|_| SendError::PathNotFound)
        }
 
+       fn create_blinded_path(&self) -> Result<BlindedPath, SendError> {
+               let recipient = self.node_signer
+                       .get_node_id(Recipient::Node)
+                       .map_err(|_| SendError::GetNodeIdFailed)?;
+               let secp_ctx = &self.secp_ctx;
+
+               let peers = self.message_recipients.lock().unwrap()
+                       .iter()
+                       .filter(|(_, peer)| matches!(peer, OnionMessageRecipient::ConnectedPeer(_)))
+                       .map(|(node_id, _ )| ForwardNode {
+                               node_id: *node_id,
+                               short_channel_id: None,
+                       })
+                       .collect::<Vec<_>>();
+
+               self.message_router
+                       .create_blinded_paths(recipient, peers, secp_ctx)
+                       .and_then(|paths| paths.into_iter().next().ok_or(()))
+                       .map_err(|_| SendError::PathNotFound)
+       }
+
        fn enqueue_onion_message<T: OnionMessageContents>(
                &self, path: OnionMessagePath, contents: T, reply_path: Option<BlindedPath>,
                log_suffix: fmt::Arguments
@@ -1043,20 +1094,48 @@ where
                )
        }
 
-       fn handle_onion_message_response<T: OnionMessageContents>(
+       /// Handles the response to an [`OnionMessage`] based on its [`ResponseInstruction`],
+       /// enqueueing any response for sending.
+       ///
+       /// This function is useful for asynchronous handling of [`OnionMessage`]s.
+       /// Handlers have the option to return [`ResponseInstruction::NoResponse`], indicating that
+       /// no immediate response should be sent. Then, they can transfer the associated [`Responder`]
+       /// to another task responsible for generating the response asynchronously. Subsequently, when
+       /// the response is prepared and ready for sending, that task can invoke this method to enqueue
+       /// the response for delivery.
+       pub fn handle_onion_message_response<T: OnionMessageContents>(
                &self, response: ResponseInstruction<T>
-       ) {
-               if let ResponseInstruction::WithoutReplyPath(response) = response {
-                       let message_type = response.message.msg_type();
-                       let _ = self.find_path_and_enqueue_onion_message(
-                               response.message, Destination::BlindedPath(response.reply_path), None,
-                               format_args!(
-                                       "when responding with {} to an onion message with path_id {:02x?}",
-                                       message_type,
-                                       response.path_id
-                               )
-                       );
-               }
+       ) -> Result<Option<SendSuccess>, SendError> {
+               let (response, create_reply_path) = match response {
+                       ResponseInstruction::WithReplyPath(response) => (response, true),
+                       ResponseInstruction::WithoutReplyPath(response) => (response, false),
+                       ResponseInstruction::NoResponse => return Ok(None),
+               };
+
+               let message_type = response.message.msg_type();
+               let reply_path = if create_reply_path {
+                       match self.create_blinded_path() {
+                               Ok(reply_path) => Some(reply_path),
+                               Err(err) => {
+                                       log_trace!(
+                                               self.logger,
+                                               "Failed to create reply path when responding with {} to an onion message \
+                                               with path_id {:02x?}: {:?}",
+                                               message_type, response.path_id, err
+                                       );
+                                       return Err(err);
+                               }
+                       }
+               } else { None };
+
+               self.find_path_and_enqueue_onion_message(
+                       response.message, Destination::BlindedPath(response.reply_path), reply_path,
+                       format_args!(
+                               "when responding with {} to an onion message with path_id {:02x?}",
+                               message_type,
+                               response.path_id
+                       )
+               ).map(|result| Some(result))
        }
 
        #[cfg(test)]
@@ -1162,14 +1241,14 @@ where
                                                        |reply_path| Responder::new(reply_path, path_id)
                                                );
                                                let response_instructions = self.offers_handler.handle_message(msg, responder);
-                                               self.handle_onion_message_response(response_instructions);
+                                               let _ = self.handle_onion_message_response(response_instructions);
                                        },
                                        ParsedOnionMessageContents::Custom(msg) => {
                                                let responder = reply_path.map(
                                                        |reply_path| Responder::new(reply_path, path_id)
                                                );
                                                let response_instructions = self.custom_handler.handle_custom_message(msg, responder);
-                                               self.handle_onion_message_response(response_instructions);
+                                               let _ = self.handle_onion_message_response(response_instructions);
                                        },
                                }
                        },