Merge pull request #16 from oipwg/nlr

add nlr check to reorganize function

lib/blockchain/chain.js

@@ -855,6 +855,9 @@ class Chain extends AsyncEmitter {
 
     assert(fork, 'No free space or data corruption.');
 
+    // Check NLR
+    if (await this.noLongReorg(tip, fork, competitor)) return true
+
     // Blocks to disconnect.
     const disconnect = [];
     let entry = tip;
@@ -912,6 +915,9 @@ class Chain extends AsyncEmitter {
 
     assert(fork, 'No free space or data corruption.');
 
+    // Check NLR
+    if (await this.noLongReorg(tip, fork, competitor)) return true
+
     // Buffer disconnected blocks.
     const disconnect = [];
     let entry = tip;
@@ -950,6 +956,48 @@ 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. Preventing reorganization: current=%h(%d) competitor=%h(%d) fork=%h(%d) reorg_size=%d nlr=%d',
+          tip.hash,
+          tip.height,
+          competitor.hash,
+          competitor.height,
+          fork.hash,
+          fork.height,
+          tip.height - fork.height,
+          this.network.nlrLimit
+        );
+
+        let indexWalk = competitor
+
+        // mark invalid_child from tip of competitor to first block of fork
+        while (indexWalk.height > fork.height) {
+          await this.setInvalid(indexWalk.hash)
+          indexWalk = await this.getPrevious(indexWalk)
+        }
+
+        // check
+        indexWalk = await this.getPrevious(indexWalk)
+        assert.strictEqual(indexWalk, fork)
+
+        return true
+      }
+    }
+    return false
+  }
+
   /**
    * Disconnect an entry from the chain (updates the tip).
    * @param {ChainEntry} entry

lib/protocol/network.js

@@ -58,6 +58,7 @@ class Network {
     this.maxFeeRate = options.maxFeeRate;
     this.selfConnect = options.selfConnect;
     this.requestMempool = options.requestMempool;
+    this.nlrLimit = options.nlrLimit;
     this.time = new TimeData();
 
     this.init();

lib/protocol/networks.js

@@ -563,6 +563,8 @@ main.selfConnect = false;
 
 main.requestMempool = false;
 
+main.nlrLimit = 100 // 100 * ~40s = ~66 minutes
+
 /*
  * Testnet (v3)
  * https://en.bitcoin.it/wiki/Testnet
@@ -800,6 +802,8 @@ testnet.selfConnect = false;
 
 testnet.requestMempool = false;
 
+testnet.nlrLimit = 50; // 50 * ~40s = ~33 minutes
+
 /*
  * Regtest
  */
@@ -1019,6 +1023,8 @@ regtest.selfConnect = true;
 
 regtest.requestMempool = true;
 
+regtest.nlrLimit = 10;
+
 /*
  * Simnet (btcd)
  */