From 7a1816a3a8949a690874c0a5bf61718676c499a5 Mon Sep 17 00:00:00 2001
From: ohryan <ryanachacon@gmail.com>
Date: Wed, 15 Jul 2020 19:07:25 -0700
Subject: [PATCH] refactor/update nlr function; check nlr for spv wallet

---
 lib/blockchain/chain.js | 75 ++++++++++++++++++++++++-----------------
 1 file changed, 45 insertions(+), 30 deletions(-)

diff --git a/lib/blockchain/chain.js b/lib/blockchain/chain.js
index c97e428d..6c8822f0 100644
--- a/lib/blockchain/chain.js
+++ b/lib/blockchain/chain.js
@@ -855,36 +855,8 @@ class Chain extends AsyncEmitter {
 
     assert(fork, 'No free space or data corruption.');
 
-    // Check NLR (No Large Reorganization)
-    if  (tip.height - fork.height >= this.nlrLimit) {
-      if (this.nlrLimit !== 0) {
-        this.logger.warning(
-          'NLR Activated: current=%h(%d) fork=%h(%d) reorg_size=%d',
-          tip.hash,
-          tip.height,
-          competitor.hash,
-          competitor.height,
-          tip.height - fork.height
-        );
-
-        const entryWithMostWork = (tip.height > competitor.height) ? tip : competitor
-
-        // mark invalid_child from tip of fork to second block of fork
-        while (entryWithMostWork.height > fork.height + 2) {
-          const previous = await this.getPrevious(entryWithMostWork)
-          this.invalidate(previous.hash)
-        }
-
-        // mark invalid first block of fork
-        const previous = await this.getPrevious(entryWithMostWork)
-        this.invalidate(previous.hash)
-
-        // check
-        assert(this.getPrevious(previous), fork)
-
-        return true
-      }
-    }
+    // Check NLR
+    if (this.noLongReorg(tip, fork, competitor)) return true
 
     // Blocks to disconnect.
     const disconnect = [];
@@ -943,6 +915,9 @@ class Chain extends AsyncEmitter {
 
     assert(fork, 'No free space or data corruption.');
 
+    // Check NLR
+    if (this.noLongReorg(tip, fork, competitor)) return true
+
     // Buffer disconnected blocks.
     const disconnect = [];
     let entry = tip;
@@ -981,6 +956,46 @@ class Chain extends AsyncEmitter {
     return this.emitAsync('reorganize', tip, competitor);
   }
 
+  /**
+   * Checks if a reorganization breaks the set nlrLimit,
+   * if it does, it invalidates necessary blocks and returns true
+   * else return false
+   * @param {ChainEntry} tip - Current tip of this chain.
+   * @param {ChainEntry} fork - The tip of the fork.
+   * @param {ChainEntry} competitor - The competing chain's tip.
+   * @returns {Promise<boolean>}
+   */
+  async noLongReorg (tip, fork, competitor) {
+    if (tip.height - fork.height >= this.network.nlrLimit) {
+      if (this.network.nlrLimit !== 0) {
+        this.logger.warning(
+          'NLR Activated: current=%h(%d) fork=%h(%d) reorg_size=%d',
+          tip.hash,
+          tip.height,
+          competitor.hash,
+          competitor.height,
+          tip.height - fork.height
+        );
+
+        // mark invalid_child from tip of fork to second block of fork
+        while (competitor.height > fork.height + 2) {
+          const previous = await this.getPrevious(competitor)
+          this.invalidate(previous.hash)
+        }
+
+        // mark invalid first block of fork
+        const previous = await this.getPrevious(competitor)
+        this.invalidate(previous.hash)
+
+        // check
+        assert(this.getPrevious(previous), fork)
+
+        return true
+      }
+    }
+    return false
+  }
+
   /**
    * Disconnect an entry from the chain (updates the tip).
    * @param {ChainEntry} entry