Fix shutdown save peers utreexo (#280)

Added code to save good utreexo peers to a anchors.json file

crates/floresta-wire/src/p2p_wire/address_man.rs

@@ -389,6 +389,20 @@ impl AddressMan {
         Ok(())
     }
 
+    /// Dumps the connected utreexo peers to a file on dir `datadir/anchors.json` in json format `
+    /// inputs are the directory to save the file and the list of ids of the connected utreexo peers
+    pub fn dump_utreexo_peers(&self, datadir: &str, peers_id: &[usize]) -> std::io::Result<()> {
+        let addresses: Vec<DiskLocalAddress> = peers_id
+            .iter()
+            .filter_map(|id| Some(self.addresses.get(id)?.to_owned().into()))
+            .collect();
+        let addresses: Result<String, serde_json::Error> = serde_json::to_string(&addresses);
+        if let Ok(addresses) = addresses {
+            std::fs::write(datadir.to_owned() + "/anchors.json", addresses)?;
+        }
+        Ok(())
+    }
+
     fn get_address_by_service(&self, service: ServiceFlags) -> Option<(usize, LocalAddress)> {
         let peers = self.good_peers_by_service.get(&service)?;
         if peers.is_empty() {

crates/floresta-wire/src/p2p_wire/node.rs

@@ -709,7 +709,7 @@ where
         for peer in self.peer_ids.iter() {
             try_and_log!(self.send_to_peer(*peer, NodeRequest::Shutdown).await);
         }
-
+        try_and_log!(self.save_utreexo_peers());
         try_and_log!(self.save_peers());
         try_and_log!(self.chain.flush());
     }
@@ -752,6 +752,23 @@ where
             .map_err(WireError::Io)
     }
 
+    /// Saves the utreexo peers to disk so we can reconnect with them later
+    pub(crate) fn save_utreexo_peers(&self) -> Result<(), WireError> {
+        let peers: &Vec<u32> = self
+            .peer_by_service
+            .get(&service_flags::UTREEXO.into())
+            .ok_or(WireError::NoPeersAvailable)?;
+        let peers_usize: Vec<usize> = peers.iter().map(|&peer| peer as usize).collect();
+        if peers_usize.is_empty() {
+            warn!("No connected utreexo peers to save to disk");
+            return Ok(());
+        }
+        info!("Saving utreexo peers to disk");
+        self.address_man
+            .dump_utreexo_peers(&self.datadir, &peers_usize)
+            .map_err(WireError::Io)
+    }
+
     pub(crate) async fn maybe_open_connection(&mut self) -> Result<(), WireError> {
         // If the user passes in a `--connect` cli argument, we only connect with
         // that particular peer.