wallet: get node client options from node on connect.

CHANGELOG.md

@@ -34,6 +34,10 @@ wallet plugin attached.
       - `nextCompaction` - when will the next compaction trigger after restart.
       - `lastCompaction` - when was the last compaction run.
   - Introduce `scan interactive` hook (start, filter)
+  - Add WS call `get options` to get `chain` options: `prune` and `spv`. This
+  allows wallet to detect capabilities of the client it connected to. E.g.
+  `prune` can be used to check the maximum rescan depth available from the node.
+  This is only called on wallet -> node connect.
 
 ### Node HTTP Client:
   - Introduce `scanInteractive` method that starts interactive rescan.

lib/client/node.js

@@ -213,6 +213,15 @@ class NodeClient extends Client {
     return this.call('watch mempool');
   }
 
+  /**
+   * Get node options.
+   * @returns {Promise}
+   */
+
+  getOptions() {
+    return this.call('get options');
+  }
+
   /**
    * Get chain tip.
    * @returns {Promise}

lib/node/http.js

@@ -586,6 +586,17 @@ class HTTP extends Server {
       return null;
     });
 
+    socket.hook('get options', () => {
+      const options = {
+        chain: {
+          spv: this.chain.options.spv,
+          prune: this.chain.options.prune
+        }
+      };
+
+      return options;
+    });
+
     socket.hook('get tip', () => {
       return this.chain.tip.encode();
     });

lib/wallet/nodeclient.js

@@ -107,6 +107,20 @@ class NodeClient extends AsyncEmitter {
     return this.on(type, handler);
   }
 
+  /**
+   * Get node options.
+   * @returns {Promise}
+   */
+
+  async getOptions() {
+    return {
+      chain: {
+        spv: this.node.chain.options.spv,
+        prune: this.node.chain.options.prune
+      }
+    };
+  }
+
   /**
    * Get chain tip.
    * @returns {Promise}
@@ -212,6 +226,16 @@ class NodeClient extends AsyncEmitter {
     return this.node.chain.getHashes(start, end);
   }
 
+  /**
+   * Reset the chain.
+   * @param {Number} height
+   * @returns {Promise}
+   */
+
+  async reset(height) {
+    return this.node.chain.reset(height);
+  }
+
   /**
    * Rescan for any missed transactions.
    * @param {Number|Hash} start - Start block.
@@ -221,9 +245,6 @@ class NodeClient extends AsyncEmitter {
    */
 
   async rescan(start) {
-    if (this.node.spv)
-      return this.node.chain.reset(start);
-
     return this.node.chain.scan(start, this.filter, (entry, txs) => {
       return this.emitAsync('block rescan', entry, txs);
     });

lib/wallet/nullclient.js

@@ -72,6 +72,20 @@ class NullClient extends EventEmitter {
     return this.on(type, handler);
   }
 
+  /**
+   * Get options.
+   * @returns {Promise}
+   */
+
+  async getOptions() {
+    return {
+      chain: {
+        spv: false,
+        chain: false
+      }
+    };
+  }
+
   /**
    * Get chain tip.
    * @returns {Promise}

lib/wallet/walletdb.js

@@ -58,12 +58,15 @@ class WalletDB extends EventEmitter {
     this.network = this.options.network;
     this.logger = this.options.logger.context('wallet');
     this.workers = this.options.workers;
-    this.client = this.options.client || new NullClient(this);
     this.feeRate = this.options.feeRate;
     this.db = bdb.create(this.options);
     this.name = 'wallet';
     this.version = 2;
 
+    // Client state
+    this.client = this.options.client || new NullClient(this);
+    this.clientInfo = null;
+
     // chain state.
     this.hasStateCache = false;
     this.state = new ChainState();
@@ -140,6 +143,7 @@ class WalletDB extends EventEmitter {
     this.client.on('disconnect', async () => {
       this.emit('disconnect');
       this.filterSent = false;
+      this.clientInfo = null;
     });
 
     this.client.bind('block connect', async (entry, txs) => {
@@ -391,7 +395,8 @@ class WalletDB extends EventEmitter {
    */
 
   async connect() {
-    return this.client.open();
+    await this.client.open();
+    this.clientInfo = await this.client.getOptions();
   }
 
   /**
@@ -400,6 +405,7 @@ class WalletDB extends EventEmitter {
    */
 
   async disconnect() {
+    this.clientInfo = null;
     return this.client.close();
   }
 
@@ -531,6 +537,9 @@ class WalletDB extends EventEmitter {
 
     const tip = await this.getTip();
 
+    if (this.clientInfo.chain.spv)
+      return this.client.reset(tip.height);
+
     return this.client.rescan(tip.hash);
   }
 
@@ -1364,7 +1373,6 @@ class WalletDB extends EventEmitter {
 
   /**
    * Get an account from the database by wid.
-   * @private
    * @param {Number} wid
    * @param {Number} index - Account index.
    * @returns {Promise} - Returns {@link Wallet}.