fix: add forgotten check for coinbase input (#3)

fix: add forgotten check for coinbase input

input.go

@@ -1,6 +1,7 @@
 package rawtx
 
 import (
+	"bytes"
 	"github.com/btcsuite/btcd/wire"
 )
 
@@ -73,7 +74,12 @@ func (in *Input) FromWireTxIn(txIn *wire.TxIn) {
 // GetType retruns the input type as a InputType
 func (in *Input) GetType() InputType {
 	if in.inputType != 0 {
+		// return the cached input type
 		return in.inputType
+	}
+
+	if in.IsCoinbase() {
+		return InCOINBASE
 	} else if in.SpendsP2PKH() {
 		return InP2PKH
 	} else if in.SpendsP2SH() {
@@ -109,6 +115,20 @@ func (in *Input) SpendsNativeSegWit() bool {
 	return false
 }
 
+// IsCoinbase checks if an input is a coinbase input by checking the previous-
+// output-index to be equal to 0xffffffff and then checking the previous-tx-hash
+// to be all zero.
+func (in *Input) IsCoinbase() bool {
+	// first do the inexpensive check if equal to 0xffffffff
+	if in.Outpoint.OutputIndex == 0xffffffff {
+		// only then check the more expensive equal for byte arrays
+		if bytes.Equal(in.Outpoint.PrevTxHash[:], make([]byte, 32)) {
+			return true
+		}
+	}
+	return false
+}
+
 // SpendsP2WSH checks if an input spends a P2WSH input.
 // Since all native SegWit inputs that aren't P2WPKH are probably
 // P2WSH this function just returns the complement for all native SegWit

input_test.go

@@ -416,7 +416,7 @@ func TestInputGetType(t *testing.T) {
 	txm[tx7] = []InputType{InP2PKH}
 	txm[tx8] = []InputType{InP2WSH}
 	txm[tx9] = []InputType{InP2WPKH}
-	txm[tx10] = []InputType{InUNKNOWN}
+	txm[tx10] = []InputType{InCOINBASE}
 	txm[tx11] = []InputType{InP2SH, InP2SH, InP2SH, InP2SH, InP2SH, InP2SH, InP2SH}
 	txm[tx12] = []InputType{InP2PKH}
 	txm[tx13] = []InputType{InP2PKH}
@@ -427,6 +427,7 @@ func TestInputGetType(t *testing.T) {
 	txm[tx21] = []InputType{InP2WSH}
 	txm[tx22] = []InputType{InP2WSH}
 	txm[tx23] = []InputType{InP2PK}
+	txm[tx24] = []InputType{InCOINBASE}
 
 	for txString, expexted := range txm {
 		tx, err := StringToTx(txString)

testdata.go

@@ -88,6 +88,10 @@ const (
 	// Satoshi to Hal in Block 170
 	// inputs: 1 (P2PK), ouputs: 1 (P2PK)
 	tx23 string = "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"
+
+	// Coinbase from Block 500342
+	// Used to test a bug fix that a coinbase was not recognized correctly
+	tx24 string = "01000000010000000000000000000000000000000000000000000000000000000000000000ffffffff5f0376a2071a2f5669614254432f4d696e6564206279206c7a6f7a313233342f2cfabe6d6da6d88f687bb14bcc0ebb42353875893e6e650aadd4f3c06645522a40c278ccb7010000000000000012d329f872eed68c722d5fafa8ed97dc000000ffffffff01807c814a000000001976a914536ffa992491508dca0354e52f32a3a7a679a53a88ac00000000"
 )
 
 // OP_RETURN tx