chain: improve locatorHashes.

lib/bcoin/chain.js

@@ -641,16 +641,19 @@ Chain.prototype.locatorHashes = function locatorHashes(obj) {
   if (obj != null) {
     if (typeof obj === 'string') {
       start = this.byHash(obj);
-      if (!start)
-        return [obj];
+      if (start) {
+        start = start.index;
+      } else {
+        // return [obj];
+        start = obj;
+      }
     } else if (typeof obj === 'number') {
       start = this.byHeight(obj);
+      if (start)
+        start = start.index;
     }
 
-    assert(start);
-
-    if (start)
-      start = start.index;
+    assert(start != null);
   }
 
   return bcoin.fullChain.prototype.locatorHashes.call(this, start);

lib/bcoin/fullchain.js

@@ -432,8 +432,11 @@ Chain.prototype.locatorHashes = function locatorHashes(start) {
 
   if (typeof start === 'string') {
     top = this.index.heights[start];
-    if (top == null)
-      return [start];
+    if (top == null) {
+      // return [start];
+      hashes.push(start);
+      top = chain.length - 1;
+    }
   } else if (typeof start === 'number') {
     top = start;
   }

lib/bcoin/pool.js

@@ -353,8 +353,12 @@ Pool.prototype._handleHeaders = function _handleHeaders(headers, peer) {
   }
 
   // Restart the getheaders process
-  // chain.locatorHashes will return [last.hash('hex')] here for now because
-  // the headers have not been added to the chain in non-headers-first mode.
+  // Technically `last` is not indexed yet so
+  // the locator hashes will not be entirely
+  // accurate. However, it shouldn't matter
+  // that much since FindForkInGlobalIndex
+  // simply tries to find the latest block in
+  // the peer's chain.
   if (last && headers.length === 2000)
     peer.loadHeaders(this.chain.locatorHashes(last), null);