WIP: add initial DAA support

lib/blockchain/chain.js

@@ -499,6 +499,10 @@ class Chain extends AsyncEmitter {
       state.flags = Script.flags.VERIFY_SIGHASH_FORKID;
     }
 
+    // DAA is now enabled.
+    if (height >= this.network.block.daaheight)
+      state.daa = true;
+
     // CHECKSEQUENCEVERIFY and median time
     // past locktimes are now usable (bip9 & bip113).
     if (await this.isActive(prev, deployments.csv)) {
@@ -2172,6 +2176,27 @@ class Chain extends AsyncEmitter {
     return this.getTarget(this.network.now(), this.tip);
   }
 
+  /**
+   * Get median of timestamp last three blocks based on timestamp.
+   * @param {ChainEntry} prev - Previous entry.
+   * @returns {Promise} - returns Entry
+   */
+
+  async getSuitableBlock(prev) {
+    const median = {};
+
+    for (let i = 0; i < 2; i++) {
+      median[prev.time] = prev;
+      prev= await this.getPrevious(prev);
+    }
+
+    const times = Object.keys(median);
+    times.sort(cmp);
+
+    const mid = times[times.length >>> 1];
+    return median[mid];
+  }
+
   /**
    * Calculate the next target.
    * @param {Number} time - Next block timestamp.
@@ -2189,6 +2214,29 @@ class Chain extends AsyncEmitter {
       return pow.bits;
     }
 
+    // IsDAAEnabled
+    if (this.state.hasDAA()) {
+      // Do not retarget
+      if (pow.targetReset) {
+        // Special behavior for testnet:
+        if (time > prev.time + pow.targetSpacing * 2)
+          return pow.bits;
+      }
+
+      // Compute the difficulty on the full adjustment interval.
+      assert(prev.height >= pow.retargetInterval);
+
+      // Get the last suitable block of the difficulty interval.
+      const last = await this.getSuitableBlock(prev);
+
+      // Get the first suitable block of the difficulty interval.
+      const height = prev.height - 144;
+      const first = await this.getSuitableBlock(await this.getAncestor(prev, height));
+
+      // Compute the target based on time eand work done during the interval.
+      return this.retarget(last, first);
+    }
+
     if ((prev.height + 1) % pow.retargetInterval === 0) {
       // Back 2 weeks
       const height = prev.height - (pow.retargetInterval - 1);
@@ -2755,6 +2803,7 @@ class DeploymentState {
     this.bip34 = false;
     this.bip91 = false;
     this.bip148 = false;
+    this.daa = false;
   }
 
   /**
@@ -2837,6 +2886,15 @@ class DeploymentState {
   hasBIP148() {
     return this.bip148;
   }
+
+  /**
+   * Test whether DAA is active.
+   * @returns {Boolean}
+   */
+
+  hasDAA() {
+    return this.daa;
+  }
 }
 
 /**

lib/protocol/networks.js

@@ -103,7 +103,9 @@ main.checkpointMap = {
   460000: '8c25fc7e414d3e868d6ce0ec473c30ad44e7e8bc1b75ef000000000000000000',
   470000: '89756d1ed75901437300af10d5ab69070a282e729c536c000000000000000000',
   // UAHF fork block:
-  478559: 'ec5e1a193601f25ff1d94b421ddead0dbefcb99cf91e65000000000000000000'
+  478559: 'ec5e1a193601f25ff1d94b421ddead0dbefcb99cf91e65000000000000000000',
+  // DAA fork block
+  504031: '9cabb6ee1b1a4c3b659d70be75810be83d0a0db665bf1e010000000000000000'
 };
 
 /**
@@ -275,6 +277,18 @@ main.block = {
 
   bip66hash: '3109b588941188a9f1c2576aae462d729b8cce9da1ea79030000000000000000',
 
+  /**
+   * Height at which DAA was activated.
+   */
+
+  daaheight: 504031,
+
+  /**
+   * Hash of the block that activated DAA
+   */
+
+  daahash: '9cabb6ee1b1a4c3b659d70be75810be83d0a0db665bf1e010000000000000000',
+
   /**
    * Safe height to start pruning.
    */
@@ -497,7 +511,9 @@ testnet.checkpointMap = {
   780000: '0381582e34c3755964dc2813e2b33e521e5596367144e1670851050000000000',
   840000: 'dac1648107bd4394e57e4083c86d42b548b1cfb119665f179ea80a0000000000',
   900000: '9bd8ac418beeb1a2cf5d68c8b5c6ebaa947a5b766e5524898d6f350000000000',
-  1050000: 'd8190cf0af7f08e179cab51d67db0b44b87951a78f7fdc31b4a01a0000000000'
+  1050000: 'd8190cf0af7f08e179cab51d67db0b44b87951a78f7fdc31b4a01a0000000000',
+  1155875: '38f1ae7f0ea8c1b589884c5fbd0b83721e3ab6759a4b897206857cf100000000',
+  1188697: 'fb47e0ab0d2448f71192a09fe61bc9c46cd3b4e7bd778091d00e170000000000'
 };
 
 testnet.lastCheckpoint = 1050000;
@@ -551,6 +567,8 @@ testnet.block = {
   bip65hash: 'b61e864fbec41dfaf09da05d1d76dc068b0dd82ee7982ff255667f0000000000',
   bip66height: 330776,
   bip66hash: '82a14b9e5ea81d4832b8e2cd3c2a6092b5a3853285a8995ec4c8042100000000',
+  daaheight: 1188697,
+  daahash: 'fb47e0ab0d2448f71192a09fe61bc9c46cd3b4e7bd778091d00e170000000000',
   pruneAfterHeight: 1000,
   keepBlocks: 10000,
   maxTipAge: 24 * 60 * 60,
@@ -692,6 +710,8 @@ regtest.block = {
   bip65hash: null,
   bip66height: 1251,
   bip66hash: null,
+  daaheight: 0,
+  daahash: null,
   pruneAfterHeight: 1000,
   keepBlocks: 10000,
   maxTipAge: 0xffffffff,
@@ -835,6 +855,8 @@ simnet.block = {
   bip65hash: 'f67ad7695d9b662a72ff3d8edbbb2de0bfa67b13974bb9910d116d5cbd863e68',
   bip66height: 0,
   bip66hash: 'f67ad7695d9b662a72ff3d8edbbb2de0bfa67b13974bb9910d116d5cbd863e68',
+  daaheight: 0,
+  daahash: null,
   pruneAfterHeight: 1000,
   keepBlocks: 10000,
   maxTipAge: 0xffffffff,