From b14bc602d45cac8191059d8ed6a5391ca7cfc68f Mon Sep 17 00:00:00 2001
From: Antoine Poinsot <darosior@protonmail.com>
Date: Mon, 17 Oct 2022 15:48:12 +0200
Subject: [PATCH] bitcoin: interface for broadcasting a transaction

---
 src/bitcoin/d/mod.rs |  8 ++++++++
 src/bitcoin/mod.rs   | 41 +++++++++++++++++++++++++++++++++++++++--
 src/testutils.rs     |  6 +++++-
 3 files changed, 52 insertions(+), 3 deletions(-)

diff --git a/src/bitcoin/d/mod.rs b/src/bitcoin/d/mod.rs
index 2bfe3a5e..c3db160e 100644
--- a/src/bitcoin/d/mod.rs
+++ b/src/bitcoin/d/mod.rs
@@ -679,6 +679,14 @@ impl BitcoinD {
             blockhash,
         }
     }
+
+    pub fn broadcast_tx(&self, tx: &bitcoin::Transaction) -> Result<(), BitcoindError> {
+        self.make_fallible_node_request(
+            "sendrawtransaction",
+            &params!(bitcoin::consensus::encode::serialize_hex(tx)),
+        )?;
+        Ok(())
+    }
 }
 // Bitcoind uses a guess for the value of verificationprogress. It will eventually get to
 // be 1, and we want to be less conservative.
diff --git a/src/bitcoin/mod.rs b/src/bitcoin/mod.rs
index 5f9a7289..ec7cf141 100644
--- a/src/bitcoin/mod.rs
+++ b/src/bitcoin/mod.rs
@@ -4,12 +4,30 @@
 pub mod d;
 pub mod poller;
 
-use d::LSBlockEntry;
+use d::{BitcoindError, LSBlockEntry};
 
-use std::{collections::HashMap, fmt, sync};
+use std::{collections::HashMap, error, fmt, sync};
 
 use miniscript::bitcoin;
 
+/// Error occuring when querying our Bitcoin backend.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum BitcoinError {
+    Broadcast(String),
+}
+
+impl fmt::Display for BitcoinError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            BitcoinError::Broadcast(reason) => {
+                write!(f, "Failed to broadcast transaction: '{}'", reason)
+            }
+        }
+    }
+}
+
+impl error::Error for BitcoinError {}
+
 /// Information about the best block in the chain
 #[derive(Debug, Clone, Eq, PartialEq, Copy)]
 pub struct BlockChainTip {
@@ -60,6 +78,9 @@ pub trait BitcoinInterface: Send {
 
     /// Get the common ancestor between the Bitcoin backend's tip and the given tip.
     fn common_ancestor(&self, tip: &BlockChainTip) -> BlockChainTip;
+
+    /// Broadcast this transaction to the Bitcoin P2P network
+    fn broadcast_tx(&self, tx: &bitcoin::Transaction) -> Result<(), BitcoinError>;
 }
 
 impl BitcoinInterface for d::BitcoinD {
@@ -234,6 +255,18 @@ impl BitcoinInterface for d::BitcoinD {
 
         ancestor
     }
+
+    fn broadcast_tx(&self, tx: &bitcoin::Transaction) -> Result<(), BitcoinError> {
+        match self.broadcast_tx(tx) {
+            Ok(()) => Ok(()),
+            Err(BitcoindError::Server(e)) => Err(BitcoinError::Broadcast(e.to_string())),
+            // We assume the Bitcoin backend doesn't fail, so it must be a JSONRPC error.
+            Err(e) => panic!(
+                "Unexpected Bitcoin error when broadcast transaction: '{}'.",
+                e
+            ),
+        }
+    }
 }
 
 // FIXME: do we need to repeat the entire trait implemenation? Isn't there a nicer way?
@@ -282,6 +315,10 @@ impl BitcoinInterface for sync::Arc<sync::Mutex<dyn BitcoinInterface + 'static>>
     fn common_ancestor(&self, tip: &BlockChainTip) -> BlockChainTip {
         self.lock().unwrap().common_ancestor(tip)
     }
+
+    fn broadcast_tx(&self, tx: &bitcoin::Transaction) -> Result<(), BitcoinError> {
+        self.lock().unwrap().broadcast_tx(tx)
+    }
 }
 
 // FIXME: We could avoid this type (and all the conversions entailing allocations) if bitcoind
diff --git a/src/testutils.rs b/src/testutils.rs
index 523dc3de..3f5b1e72 100644
--- a/src/testutils.rs
+++ b/src/testutils.rs
@@ -1,5 +1,5 @@
 use crate::{
-    bitcoin::{BitcoinInterface, BlockChainTip, UTxO},
+    bitcoin::{BitcoinError, BitcoinInterface, BlockChainTip, UTxO},
     config::{BitcoinConfig, Config},
     database::{Coin, DatabaseConnection, DatabaseInterface, SpendBlock},
     DaemonHandle,
@@ -66,6 +66,10 @@ impl BitcoinInterface for DummyBitcoind {
     fn common_ancestor(&self, _: &BlockChainTip) -> BlockChainTip {
         todo!()
     }
+
+    fn broadcast_tx(&self, _: &bitcoin::Transaction) -> Result<(), BitcoinError> {
+        todo!()
+    }
 }
 
 pub struct DummyDb {