wip: support submarine swap in bifrost

* messages resembles those of [peerswap protocol](https://github.com/ElementsProject/peerswap/blob/master/docs/peer-protocol.md#the-swap_in_request-message)
* It does not support compatibility with peerswap daemon
* LNPBP specification is not ready yet.

lnp2p/src/bifrost/mod.rs

@@ -172,6 +172,7 @@ mod app;
 mod channel;
 mod ctrl;
 mod msg;
+mod peerswap;
 mod proposals;
 mod types;
 
@@ -185,6 +186,7 @@ use internet2::{CreateUnmarshaller, Payload, Unmarshall, Unmarshaller};
 use lnpbp::bech32::Blob;
 pub use msg::Msg;
 use once_cell::sync::Lazy;
+pub use peerswap::*;
 pub use proposals::*;
 use strict_encoding::{self, StrictDecode, StrictEncode};
 pub use types::{
@@ -257,6 +259,49 @@ pub enum Messages {
 
     #[api(type = 0x0028)]
     CloseChannel(CloseChannel),
+
+    #[api(type = 0x0040)]
+    SwapInRequest(SwapInRequestMsg),
+
+    #[api(type = 0x0041)]
+    SwapInAgreement(SwapInAgreementMsg),
+
+    #[api(type = 0x0042)]
+    SwapOutRequest(SwapOutRequestMsg),
+
+    #[api(type = 0x0043)]
+    SwapOutAgreement(SwapOutAgreementMsg),
+
+    #[api(type = 0x0044)]
+    OpeningTxBroadcasted(OpeningTxBroadcastedMsg),
+
+    #[api(type = 0x0045)]
+    Cancel(CancelMsg),
+
+    #[api(type = 0x0046)]
+    CoopClose(CoopCloseMsg),
+}
+
+impl Messages {
+    pub fn swap_id(&self) -> Option<&SwapId> {
+        match self {
+            Self::SwapInRequest(SwapInRequestMsg { swap_id, .. })
+            | Self::SwapOutRequest(SwapOutRequestMsg { swap_id, .. })
+            | Self::SwapInAgreement(SwapInAgreementMsg { swap_id, .. })
+            | Self::SwapOutAgreement(SwapOutAgreementMsg { swap_id, .. })
+            | Self::OpeningTxBroadcasted(OpeningTxBroadcastedMsg {
+                swap_id,
+                ..
+            })
+            | Self::Cancel(CancelMsg { swap_id, .. })
+            | Self::CoopClose(CoopCloseMsg { swap_id, .. }) => Some(swap_id),
+            _ => None,
+        }
+    }
+
+    pub fn is_swap_msg(&self) -> bool {
+        self.swap_id().is_some()
+    }
 }
 
 impl StrictEncode for Messages {

lnp2p/src/bifrost/peerswap.rs

@@ -0,0 +1,300 @@
+// LNP P2P library, plmeneting both bolt (BOLT) and Bifrost P2P messaging
+// system for Lightning network protocol (LNP)
+//
+// Written in 2020-2021 by
+//     Dr. Maxim Orlovsky <orlovsky@pandoracore.com>
+//
+// To the extent possible under law, the author(s) have dedicated all
+// copyright and related and neighboring rights to this software to
+// the public domain worldwide. This software is distributed without
+// any warranty.
+//
+// You should have received a copy of the MIT License
+// along with this software.
+// If not, see <https://opensource.org/licenses/MIT>.
+
+use amplify::{Display, Slice32};
+use bitcoin::hashes::{sha256, sha256t};
+use bitcoin::Txid;
+use lnpbp::chain::AssetId;
+use secp256k1::{PublicKey, SecretKey};
+#[cfg(feature = "serde")]
+use serde_with::{As, DisplayFromStr};
+
+use crate::bolt;
+
+pub const PROTOCOL_VERSION: u16 = 1;
+pub const BIFROST_APP_PEERSWAP: u16 = 0x8008;
+
+// SHA256("bifrost:swap")
+const SWAP_ID_MIDSTATE: [u8; 32] = [
+    0x4e, 0x2e, 0x6e, 0xb2, 0xa3, 0xda, 0x16, 0xbc, 0x03, 0xe3, 0x38, 0x30,
+    0xb3, 0xfa, 0xae, 0x6f, 0xe2, 0x76, 0x00, 0x1b, 0x2e, 0x79, 0xf1, 0x8f,
+    0xd3, 0x8c, 0x43, 0xdc, 0x79, 0xfb, 0x99, 0xdd,
+];
+
+/// Tag used for [`SwapId`] hash type
+pub struct SwapIdTag;
+
+impl sha256t::Tag for SwapIdTag {
+    #[inline]
+    fn engine() -> sha256::HashEngine {
+        let midstate = sha256::Midstate::from_inner(SWAP_ID_MIDSTATE);
+        sha256::HashEngine::from_midstate(midstate, 64)
+    }
+}
+
+#[derive(
+    Clone,
+    Copy,
+    PartialEq,
+    Eq,
+    PartialOrd,
+    Ord,
+    Hash,
+    Debug,
+    Display,
+    Default,
+    Wrapper,
+    From,
+    NetworkEncode,
+    NetworkDecode
+)]
+#[display(LowerHex)]
+#[wrapper(FromStr, LowerHex, UpperHex, BorrowSlice)]
+#[cfg_attr(
+    feature = "serde",
+    serde_as,
+    derive(Serialize, Deserialize),
+    serde(crate = "serde_crate", transparent)
+)]
+pub struct SwapId(
+    #[cfg_attr(feature = "serde", serde(with = "As::<DisplayFromStr>"))]
+    Slice32,
+);
+
+impl SwapId {
+    #[inline]
+    pub fn random() -> Self {
+        SwapId::from(Slice32::random())
+    }
+}
+
+#[derive(
+    Clone,
+    PartialEq,
+    Eq,
+    PartialOrd,
+    Ord,
+    Hash,
+    Debug,
+    Display,
+    NetworkEncode,
+    NetworkDecode
+)]
+#[cfg_attr(
+    feature = "serde",
+    serde_as,
+    derive(Serialize, Deserialize),
+    serde(crate = "serde_crate")
+)]
+#[display(Debug)]
+#[network_encoding(use_tlv)]
+pub struct SwapInRequestMsg {
+    pub protocol_version: u64,
+    pub swap_id: SwapId,
+    pub asset: Option<AssetId>,
+    pub network: String,
+    pub scid: bolt::ChannelId,
+    pub amount: u64,
+    pub pubkey: PublicKey,
+}
+
+#[derive(Clone, Ord, PartialOrd, Eq, PartialEq, Hash, Debug, Display, Error)]
+#[display(doc_comments)]
+pub enum ValidationError {
+    /// Network and asset has different value.
+    NetworkMismatch,
+
+    /// Unknown Network {0}
+    UnknownNetwork(String),
+}
+
+impl SwapInRequestMsg {
+    pub fn validate(&self) -> Result<(), ValidationError> {
+        let _network_ok = {
+            match self.network.as_str() {
+                "mainnet" => Ok(()),
+                "testnet" => Ok(()),
+                "testnet3" => Ok(()),
+                "signet" => Ok(()),
+                "regtest" => Ok(()),
+                x => Err(ValidationError::UnknownNetwork(x.to_string())),
+            }
+        }?;
+
+        Ok(())
+    }
+}
+
+#[derive(
+    Clone,
+    PartialEq,
+    Eq,
+    PartialOrd,
+    Ord,
+    Debug,
+    Display,
+    NetworkEncode,
+    NetworkDecode
+)]
+#[cfg_attr(
+    feature = "serde",
+    serde_as,
+    derive(Serialize, Deserialize),
+    serde(crate = "serde_crate")
+)]
+#[display(Debug)]
+#[network_encoding(use_tlv)]
+pub struct SwapInAgreementMsg {
+    pub protocol_version: u64,
+    pub swap_id: SwapId,
+    pub pubkey: PublicKey,
+    pub premium: u64,
+}
+
+#[derive(
+    Clone,
+    PartialEq,
+    Eq,
+    Hash,
+    Ord,
+    PartialOrd,
+    Debug,
+    Display,
+    NetworkEncode,
+    NetworkDecode
+)]
+#[cfg_attr(
+    feature = "serde",
+    serde_as,
+    derive(Serialize, Deserialize),
+    serde(crate = "serde_crate")
+)]
+#[display(Debug)]
+#[network_encoding(use_tlv)]
+pub struct SwapOutRequestMsg {
+    pub protocol_version: u64,
+    pub swap_id: SwapId,
+    pub asset: Option<AssetId>,
+    pub network: String,
+    pub scid: bolt::ChannelId,
+    pub amount: u64,
+    pub pubkey: PublicKey,
+}
+
+#[derive(
+    Clone,
+    PartialEq,
+    Eq,
+    Hash,
+    Ord,
+    PartialOrd,
+    Debug,
+    Display,
+    NetworkEncode,
+    NetworkDecode
+)]
+#[cfg_attr(
+    feature = "serde",
+    serde_as,
+    derive(Serialize, Deserialize),
+    serde(crate = "serde_crate")
+)]
+#[display(Debug)]
+#[network_encoding(use_tlv)]
+pub struct SwapOutAgreementMsg {
+    pub protocol_version: u64,
+    pub swap_id: SwapId,
+    pub pubkey: PublicKey,
+    pub payreq: String,
+}
+
+#[derive(
+    Clone,
+    PartialEq,
+    Eq,
+    Hash,
+    Ord,
+    PartialOrd,
+    Debug,
+    Display,
+    NetworkEncode,
+    NetworkDecode
+)]
+#[cfg_attr(
+    feature = "serde",
+    serde_as,
+    derive(Serialize, Deserialize),
+    serde(crate = "serde_crate")
+)]
+#[display(Debug)]
+#[network_encoding(use_tlv)]
+pub struct OpeningTxBroadcastedMsg {
+    pub swap_id: SwapId,
+    pub payreq: String,
+    pub tx_id: Txid,
+    pub script_out: u64,
+    pub blinding_key: SecretKey,
+}
+
+#[derive(
+    Clone,
+    PartialEq,
+    Eq,
+    Hash,
+    Ord,
+    PartialOrd,
+    Debug,
+    Display,
+    NetworkEncode,
+    NetworkDecode
+)]
+#[cfg_attr(
+    feature = "serde",
+    serde_as,
+    derive(Serialize, Deserialize),
+    serde(crate = "serde_crate")
+)]
+#[display(Debug)]
+#[network_encoding(use_tlv)]
+pub struct CancelMsg {
+    pub swap_id: SwapId,
+    pub message: String,
+}
+
+#[derive(
+    Clone,
+    PartialEq,
+    Eq,
+    Hash,
+    Ord,
+    PartialOrd,
+    Debug,
+    Display,
+    NetworkEncode,
+    NetworkDecode
+)]
+#[cfg_attr(
+    feature = "serde",
+    serde_as,
+    derive(Serialize, Deserialize),
+    serde(crate = "serde_crate")
+)]
+#[display(Debug)]
+#[network_encoding(use_tlv)]
+pub struct CoopCloseMsg {
+    pub swap_id: SwapId,
+    pub message: String,
+    pub privkey: SecretKey,
+}

lnp2p/src/bifrost/types.rs

@@ -59,6 +59,12 @@ impl sha256t::Tag for ChannelIdTag {
 )]
 #[wrapper(Debug, LowerHex, BorrowSlice)]
 #[wrapper(Index, IndexRange, IndexFrom, IndexTo, IndexFull)]
+#[cfg_attr(
+    feature = "serde",
+    serde_as,
+    derive(Serialize, Deserialize),
+    serde(crate = "serde_crate", transparent)
+)]
 pub struct ChannelId(sha256t::Hash<ChannelIdTag>);
 
 impl ChannelId {

lnp2p/src/bolt/types.rs

@@ -326,6 +326,11 @@ pub struct Alias(
 )]
 #[derive(LightningEncode, LightningDecode)]
 #[cfg_attr(feature = "strict_encoding", derive(NetworkEncode, NetworkDecode))]
+#[cfg_attr(
+    feature = "serde",
+    derive(Serialize, Deserialize),
+    serde(crate = "serde_crate")
+)]
 #[display("{block_height}x{tx_index}x{output_index}")]
 pub struct ShortChannelId {
     pub block_height: u24,