From 89cbdac61ef619fe9ccdb64a5ba3a78ccd75c0db Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Wed, 15 Mar 2017 08:48:28 -0700
Subject: [PATCH] rpc: more gbt/getwork improvements.

---
 lib/http/rpc.js | 50 ++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 45 insertions(+), 5 deletions(-)

diff --git a/lib/http/rpc.js b/lib/http/rpc.js
index 7d0a406e..506954f0 100644
--- a/lib/http/rpc.js
+++ b/lib/http/rpc.js
@@ -1120,11 +1120,19 @@ RPC.prototype.getBlockTemplate = co(function* getBlockTemplate(args, help) {
           // Prefer value if they support it.
           valueCap = true;
           break;
-        case 'coinbase/append':
-          break;
       }
     }
 
+    // BIP22 states that we can't have coinbasetxn
+    // _and_ coinbasevalue in the same template.
+    // The problem is, many clients _say_ they
+    // support coinbasetxn when they don't (ckpool).
+    // To make matters worse, some clients will
+    // parse an undefined `coinbasevalue` as zero.
+    // Because of all of this, coinbasetxn is
+    // disabled for now.
+    valueCap = true;
+
     if (txnCap && !valueCap) {
       if (this.miner.addresses.length === 0) {
         throw new RPCError(errs.MISC_ERROR,
@@ -1173,11 +1181,29 @@ RPC.prototype._createTemplate = co(function* _createTemplate(version, coinbase,
   var dep, deps, json, name, deploy;
   var state;
 
+  // The miner doesn't support
+  // versionbits. Force them to
+  // encode our version.
+  if (version >= 2)
+    mutable.push('version/force');
+
+  // Allow the miner to change
+  // our provided coinbase.
+  // Note that these are implied
+  // without `coinbasetxn`.
+  if (coinbase) {
+    mutable.push('coinbase');
+    mutable.push('coinbase/append');
+    mutable.push('generation');
+  }
+
+  // Build an index of every transaction.
   for (i = 0; i < attempt.items.length; i++) {
     entry = attempt.items[i];
     index[entry.hash] = i;
   }
 
+  // Calculate dependencies for each transaction.
   for (i = 0; i < attempt.items.length; i++) {
     entry = attempt.items[i];
     tx = entry.tx;
@@ -1203,9 +1229,7 @@ RPC.prototype._createTemplate = co(function* _createTemplate(version, coinbase,
     });
   }
 
-  if (version >= 2)
-    mutable.push('version/force');
-
+  // Calculate version based on given rules.
   for (i = 0; i < this.network.deploys.length; i++) {
     deploy = this.network.deploys[i];
     state = yield this.chain.getState(this.chain.tip, deploy);
@@ -1280,9 +1304,15 @@ RPC.prototype._createTemplate = co(function* _createTemplate(version, coinbase,
     json.weightlimit = consensus.MAX_BLOCK_WEIGHT;
   }
 
+  // The client wants a coinbasetxn
+  // instead of a coinbasevalue.
   if (coinbase) {
     tx = attempt.toCoinbase();
 
+    // Pop off the nonces.
+    tx.inputs[0].script.code.pop();
+    tx.inputs[0].script.compile();
+
     if (attempt.witness) {
       // We don't include the commitment
       // output (see bip145).
@@ -2198,6 +2228,11 @@ RPC.prototype.updateWork = co(function* updateWork() {
   this.bindChain();
 
   if (attempt) {
+    if (attempt.address.isNull()) {
+      throw new RPCError(errs.MISC_ERROR,
+        'No addresses available for coinbase.');
+    }
+
     this.miner.updateTime(attempt);
 
     if (++this.nonce2 === 0x100000000) {
@@ -2216,6 +2251,11 @@ RPC.prototype.updateWork = co(function* updateWork() {
     return attempt;
   }
 
+  if (this.miner.addresses.length === 0) {
+    throw new RPCError(errs.MISC_ERROR,
+      'No addresses available for coinbase.');
+  }
+
   attempt = yield this.miner.createBlock();
 
   n1 = this.nonce1;