From cee207c64caee6b2471ab73dce0b11c8762346cb Mon Sep 17 00:00:00 2001
From: Dave Collins <dave@davec.name>
Date: Fri, 12 Aug 2016 19:29:28 -0500
Subject: [PATCH] txscript: Expose AddOps on ScriptBuilder. (#734)
This exposes a new function on the ScriptBuilder type named AddOps that
allows multiple opcodes to be added via a single call and adds tests to
exercise the new function.
Finally, it updates a couple of places in the signing code that were
abusing the interface by setting its private script directly to use the
new public function instead.
---
txscript/scriptbuilder.go | 21 +++++++++++++++++++++
txscript/scriptbuilder_test.go | 20 ++++++++++++++++++++
txscript/sign.go | 7 +++----
3 files changed, 44 insertions(+), 4 deletions(-)
diff --git a/txscript/scriptbuilder.go b/txscript/scriptbuilder.go
index 6c8f641e..b22af624 100644
--- a/txscript/scriptbuilder.go
+++ b/txscript/scriptbuilder.go
@@ -73,6 +73,27 @@ func (b *ScriptBuilder) AddOp(opcode byte) *ScriptBuilder {
return b
}
+// AddOps pushes the passed opcodes to the end of the script. The script will
+// not be modified if pushing the opcodes would cause the script to exceed the
+// maximum allowed script engine size.
+func (b *ScriptBuilder) AddOps(opcodes []byte) *ScriptBuilder {
+ if b.err != nil {
+ return b
+ }
+
+ // Pushes that would cause the script to exceed the largest allowed
+ // script size would result in a non-canonical script.
+ if len(b.script)+len(opcodes) > maxScriptSize {
+ str := fmt.Sprintf("adding opcodes would exceed the maximum "+
+ "allowed canonical script length of %d", maxScriptSize)
+ b.err = ErrScriptNotCanonical(str)
+ return b
+ }
+
+ b.script = append(b.script, opcodes...)
+ return b
+}
+
// canonicalDataSize returns the number of bytes the canonical encoding of the
// data will take.
func canonicalDataSize(data []byte) int {
diff --git a/txscript/scriptbuilder_test.go b/txscript/scriptbuilder_test.go
index 677c0cf0..904fd79f 100644
--- a/txscript/scriptbuilder_test.go
+++ b/txscript/scriptbuilder_test.go
@@ -38,6 +38,7 @@ func TestScriptBuilderAddOp(t *testing.T) {
},
}
+ // Run tests and individually add each op via AddOp.
builder := txscript.NewScriptBuilder()
t.Logf("Running %d tests", len(tests))
for i, test := range tests {
@@ -58,6 +59,25 @@ func TestScriptBuilderAddOp(t *testing.T) {
continue
}
}
+
+ // Run tests and bulk add ops via AddOps.
+ t.Logf("Running %d tests", len(tests))
+ for i, test := range tests {
+ builder.Reset()
+ result, err := builder.AddOps(test.opcodes).Script()
+ if err != nil {
+ t.Errorf("ScriptBuilder.AddOps #%d (%s) unexpected "+
+ "error: %v", i, test.name, err)
+ continue
+ }
+ if !bytes.Equal(result, test.expected) {
+ t.Errorf("ScriptBuilder.AddOps #%d (%s) wrong result\n"+
+ "got: %x\nwant: %x", i, test.name, result,
+ test.expected)
+ continue
+ }
+ }
+
}
// TestScriptBuilderAddInt64 tests that pushing signed integers to a script via
diff --git a/txscript/sign.go b/txscript/sign.go
index e810bd0c..f208a865 100644
--- a/txscript/sign.go
+++ b/txscript/sign.go
@@ -203,7 +203,7 @@ func mergeScripts(chainParams *chaincfg.Params, tx *wire.MsgTx, idx int,
// Reappend the script and return the result.
builder := NewScriptBuilder()
- builder.script = mergedScript
+ builder.AddOps(mergedScript)
builder.AddData(script)
finalScript, _ := builder.Script()
return finalScript
@@ -394,10 +394,9 @@ func SignTxOutput(chainParams *chaincfg.Params, tx *wire.MsgTx, idx int,
return nil, err
}
- // This is a bad thing. Append the p2sh script as the last
- // push in the script.
+ // Append the p2sh script as the last push in the script.
builder := NewScriptBuilder()
- builder.script = realSigScript
+ builder.AddOps(realSigScript)
builder.AddData(sigScript)
sigScript, _ = builder.Script()