Add conditional break in parsing the script after op return… (#170)

* Added conditional break in parsing the script after op return… … so long as we are not in a conditional block. This is to get the library in line with v1.0.15.1 of SV node as outlined within this issue: bitcoin-sv/bitcoin-sv#296 Logic should match SV node here: https://github.com/bitcoin-sv/bitcoin-sv/blob/89d55a8ddb0e29f4786e11efad1e92cdefd0b9c5/src/script/script.cpp#L38 Signed-off-by: Darren Kellenschwiler <[email protected]> * typo Signed-off-by: Darren Kellenschwiler <[email protected]> * Add unit test for Parse function --------- Signed-off-by: Darren Kellenschwiler <[email protected]> Co-authored-by: Michael Boeckli <[email protected]>
libsv · Aug 28, 2023 · ebd4987 · ebd4987
1 parent 43ccba7
commit ebd4987
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diff --git a/bscript/interpreter/opcodeparser.go b/bscript/interpreter/opcodeparser.go
@@ -136,6 +136,7 @@ func (o *ParsedOpcode) enforceMinimumDataPush() error {
 func (p *DefaultOpcodeParser) Parse(s *bscript.Script) (ParsedScript, error) {
 	script := *s
 	parsedOps := make([]ParsedOpcode, 0, len(script))
+	conditionalBlock := 0
 
 	for i := 0; i < len(script); {
 		instruction := script[i]
@@ -145,6 +146,22 @@ func (p *DefaultOpcodeParser) Parse(s *bscript.Script) (ParsedScript, error) {
 			return nil, errs.NewError(errs.ErrInvalidParams, "tx and previous output must be supplied for checksig")
 		}
 
+		switch parsedOp.op.val {
+		case bscript.OpIF, bscript.OpNOTIF, bscript.OpVERIF, bscript.OpVERNOTIF:
+			conditionalBlock++
+		case bscript.OpENDIF:
+			conditionalBlock--
+		case bscript.OpRETURN:
+			// If we are not in a conditional block, we end script evaluation.
+			// This must be the final evaluated opcode, everything after is ignored.
+			if conditionalBlock == 0 {
+				parsedOps = append(parsedOps, parsedOp)
+				return parsedOps, nil
+			}
+			// If we are in an conditional block, we continue parsing the other branches,
+			// therefore all data must adhere to push data rules.
+		}
+
 		switch {
 		case parsedOp.op.length == 1:
 			i++

diff --git a/bscript/interpreter/opcodeparser_test.go b/bscript/interpreter/opcodeparser_test.go
@@ -9,6 +9,7 @@ import (
 
 	"github.com/libsv/go-bt/v2/bscript"
 	"github.com/libsv/go-bt/v2/bscript/interpreter/errs"
+	"github.com/stretchr/testify/require"
 )
 
 // TestOpcodeDisabled tests the opcodeDisabled function manually because all
@@ -28,3 +29,65 @@ func TestOpcodeDisabled(t *testing.T) {
 		}
 	}
 }
+
+func TestParse(t *testing.T) {
+	tt := []struct {
+		name            string
+		scriptHexString string
+
+		expectedParsedScript ParsedScript
+	}{
+		{
+			name:            "1 op return",
+			scriptHexString: "0168776a0024dc",
+
+			expectedParsedScript: ParsedScript{
+				ParsedOpcode{
+					op: opcode{
+						val:    bscript.OpDATA1,
+						name:   "OP_DATA_1",
+						length: 2,
+						exec:   opcodePushData,
+					},
+					Data: []byte{bscript.OpENDIF},
+				},
+				ParsedOpcode{
+					op: opcode{
+						val:    bscript.OpNIP,
+						name:   "OP_NIP",
+						length: 1,
+						exec:   opcodeNip,
+					},
+					Data: nil,
+				},
+				ParsedOpcode{
+					op: opcode{
+						val:    bscript.OpRETURN,
+						name:   "OP_RETURN",
+						length: 1,
+						exec:   opcodeReturn,
+					},
+					Data: nil,
+				},
+			},
+		},
+	}
+
+	for _, tc := range tt {
+		t.Run(tc.name, func(t *testing.T) {
+			s, err := bscript.NewFromHexString(tc.scriptHexString)
+			require.NoError(t, err)
+
+			codeParser := DefaultOpcodeParser{}
+			p, err := codeParser.Parse(s)
+			require.NoError(t, err)
+
+			for i := range p {
+				require.Equal(t, tc.expectedParsedScript[i].Data, p[i].Data)
+				require.Equal(t, tc.expectedParsedScript[i].op.length, p[i].op.length)
+				require.Equal(t, tc.expectedParsedScript[i].op.name, p[i].op.name)
+				require.Equal(t, tc.expectedParsedScript[i].op.val, p[i].op.val)
+			}
+		})
+	}
+}