From ae394fad114901f05b54c6f80e851c6b9fadb192 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Sat, 5 Dec 2015 20:53:06 -0800
Subject: [PATCH] improve tx.maxSize for p2sh and multisig.

---
 lib/bcoin/tx.js | 46 +++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 39 insertions(+), 7 deletions(-)

diff --git a/lib/bcoin/tx.js b/lib/bcoin/tx.js
index c49cf046..881eac3b 100644
--- a/lib/bcoin/tx.js
+++ b/lib/bcoin/tx.js
@@ -355,7 +355,10 @@ TX.prototype.isCoinbase = function isCoinbase() {
   return this.inputs.length === 1 && +this.inputs[0].out.hash === 0;
 };
 
-TX.prototype.maxSize = function maxSize() {
+TX.prototype.maxSize = function maxSize(m, n) {
+  m = m || 1;
+  n = n || 1;
+
   // Create copy with 0-script inputs
   var copy = this.clone();
   copy.inputs.forEach(function(input) {
@@ -367,7 +370,8 @@ TX.prototype.maxSize = function maxSize() {
   // Add size for signatures and public keys
   copy.inputs.forEach(function(input) {
     var s = input.out.tx.outputs[input.out.index].script;
-    if (bcoin.script.isPubkeyhash(s)) {
+
+    if (bcoin.script.isPubkeyhash(s) || bcoin.script.isSimplePubkeyhash(s)) {
       // Signature + len
       size += 74;
       // Pub key + len
@@ -375,11 +379,39 @@ TX.prototype.maxSize = function maxSize() {
       return;
     }
 
-    // Multisig
-    // Empty byte
-    size += 1;
-    // Signature + len
-    size += 74;
+    if (bcoin.script.isMultisig(s)) {
+      // Multisig
+      // Empty byte
+      size += 1;
+      // Signature + len
+      size += 74 * m;
+      return;
+    }
+
+    // 1 empty byte
+    // 1 mcode byte
+    // loop:
+    //   1 byte key length
+    //   65? byte key
+    // 1 ncode byte
+    // 1 checkmultisig byte
+    if (bcoin.script.isScripthash(s)) {
+      // Multisig
+      // Empty byte
+      size += 1;
+      // Signature + len
+      size += 74 * m;
+      // Redeem script
+      // m byte
+      size += 1;
+      // 1 byte length + 65 byte pubkey
+      size += 66 * n;
+      // n byte
+      size += 1;
+      // checkmultisig byte
+      size += 1;
+      return;
+    }
   });
 
   return size;