commands: add a new 'startrescan' command

doc/API.md

@@ -13,6 +13,7 @@ Commands must be sent as valid JSONRPC 2.0 requests, ending with a `\n`.
 | [`listspendtxs`](#listspendtxs)                             | List all stored Spend transactions                   |
 | [`delspendtx`](#delspendtx)                                 | Delete a stored Spend transaction                    |
 | [`broadcastspend`](#broadcastspend)                         | Finalize a stored Spend PSBT, and broadcast it       |
+| [`startrescan`](#startrescan)                               | Start rescanning the block chain from a given date   |
 
 # Reference
 
@@ -199,3 +200,19 @@ This command does not return anything for now.
 
 | Field          | Type      | Description                                          |
 | -------------- | --------- | ---------------------------------------------------- |
+
+
+### `startrescan`
+
+#### Request
+
+| Field        | Type   | Description                                            |
+| ------------ | ------ | ------------------------------------------------------ |
+| `timestamp`  | int    | Date to start rescanning from, as a UNIX timestamp     |
+
+#### Response
+
+This command does not return anything for now.
+
+| Field          | Type      | Description                                          |
+| -------------- | --------- | ---------------------------------------------------- |

src/commands/mod.rs

@@ -38,6 +38,9 @@ const MAX_FEE: u64 = bitcoin::blockdata::constants::COIN_VALUE;
 // Assume that paying more than 1000sat/vb in feerate is a bug.
 const MAX_FEERATE: u64 = bitcoin::blockdata::constants::COIN_VALUE;
 
+// Timestamp in the header of the genesis block. Used for sanity checks.
+const MAINNET_GENESIS_TIME: u32 = 1231006505;
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum CommandError {
     NoOutpoint,
@@ -56,6 +59,8 @@ pub enum CommandError {
     // FIXME: when upgrading Miniscript put the actual error there
     SpendFinalization(String),
     TxBroadcast(String),
+    AlreadyRescanning,
+    InsaneRescanTimestamp(u32),
 }
 
 impl fmt::Display for CommandError {
@@ -82,6 +87,11 @@ impl fmt::Display for CommandError {
                 write!(f, "Failed to finalize the spend transaction PSBT: '{}'.", e)
             }
             Self::TxBroadcast(e) => write!(f, "Failed to broadcast transaction: '{}'.", e),
+            Self::AlreadyRescanning => write!(
+                f,
+                "There is already a rescan ongoing. Please wait for it to complete first."
+            ),
+            Self::InsaneRescanTimestamp(t) => write!(f, "Insane timestamp '{}'.", t),
         }
     }
 }
@@ -490,6 +500,26 @@ impl DaemonControl {
             Err(BitcoinError::Broadcast(e)) => Err(CommandError::TxBroadcast(e)),
         }
     }
+
+    /// Trigger a rescan of the block chain for transactions involving our main descriptor between
+    /// the given date and the current tip.
+    /// The date must be after the genesis block time and before the current tip blocktime.
+    pub fn start_rescan(&self, timestamp: u32) -> Result<(), CommandError> {
+        let mut db_conn = self.db.connection();
+
+        if db_conn.rescan_timestamp().is_some() {
+            return Err(CommandError::AlreadyRescanning);
+        }
+        if timestamp < MAINNET_GENESIS_TIME || timestamp >= self.bitcoin.tip_time() {
+            return Err(CommandError::InsaneRescanTimestamp(timestamp));
+        }
+
+        self.bitcoin
+            .start_rescan(&self.config.main_descriptor, timestamp);
+        db_conn.set_rescan(timestamp);
+
+        Ok(())
+    }
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]

src/jsonrpc/api.rs

@@ -84,6 +84,18 @@ fn broadcast_spend(control: &DaemonControl, params: Params) -> Result<serde_json
     Ok(serde_json::json!({}))
 }
 
+fn start_rescan(control: &DaemonControl, params: Params) -> Result<serde_json::Value, Error> {
+    let timestamp: u32 = params
+        .get(0, "timestamp")
+        .ok_or_else(|| Error::invalid_params("Missing 'timestamp' parameter."))?
+        .as_u64()
+        .and_then(|t| t.try_into().ok())
+        .ok_or_else(|| Error::invalid_params("Invalid 'timestamp' parameter."))?;
+    control.start_rescan(timestamp)?;
+
+    Ok(serde_json::json!({}))
+}
+
 /// Handle an incoming JSONRPC2 request.
 pub fn handle_request(control: &DaemonControl, req: Request) -> Result<Response, Error> {
     let result = match req.method.as_str() {
@@ -111,6 +123,12 @@ pub fn handle_request(control: &DaemonControl, req: Request) -> Result<Response,
         "getnewaddress" => serde_json::json!(&control.get_new_address()),
         "listcoins" => serde_json::json!(&control.list_coins()),
         "listspendtxs" => serde_json::json!(&control.list_spend()),
+        "startrescan" => {
+            let params = req
+                .params
+                .ok_or_else(|| Error::invalid_params("Missing 'timestamp' parameter."))?;
+            start_rescan(control, params)?
+        }
         "stop" => serde_json::json!({}),
         "updatespend" => {
             let params = req

src/jsonrpc/mod.rs

@@ -159,7 +159,9 @@ impl From<commands::CommandError> for Error {
             | commands::CommandError::InvalidOutputValue(..)
             | commands::CommandError::InsufficientFunds(..)
             | commands::CommandError::UnknownSpend(..)
-            | commands::CommandError::SpendFinalization(..) => {
+            | commands::CommandError::SpendFinalization(..)
+            | commands::CommandError::InsaneRescanTimestamp(..)
+            | commands::CommandError::AlreadyRescanning => {
                 Error::new(ErrorCode::InvalidParams, e.to_string())
             }
             commands::CommandError::SanityCheckFailure(_) => {