Added AddressFromScript method

Author: mrz1836

README.md

@@ -40,10 +40,11 @@ View the generated [documentation](https://pkg.go.dev/github.com/bitcoinschema/g
 
 ### Features
 - [Sign](sign.go) / [Verify](verify.go) Bitcoin Message
-- [Private key (string) to Address (string)](address.go)
-- [Address from Private key (bsvec.PrivateKey)](address.go)
-- [Create Private Key](private_key.go)
-- [Create PubKey From Private Key](pubkey.go)
+- [PrivateKey (string) to Address (string)](address.go)
+- [Address from PrivateKey (bsvec.PrivateKey)](address.go)
+- [Address from Script](address.go)
+- [Create PrivateKey](private_key.go)
+- [Create PubKey from PrivateKey](pubkey.go)
 
 
 <details>

address.go

@@ -2,13 +2,15 @@ package bitcoin
 
 import (
 	"bytes"
+	"encoding/hex"
 	"errors"
 	"fmt"
 
 	"crypto/sha256"
 
 	"github.com/bitcoinsv/bsvd/bsvec"
 	"github.com/bitcoinsv/bsvd/chaincfg"
+	"github.com/bitcoinsv/bsvd/txscript"
 	"github.com/bitcoinsv/bsvutil"
 )
 
@@ -72,6 +74,22 @@ func (a *A25) ComputeChecksum() (c [4]byte) {
 	return
 }
 
+// ValidA58 validates a base58 encoded bitcoin address.  An address is valid
+// if it can be decoded into a 25 byte address, the version number is 0,
+// and the checksum validates.  Return value ok will be true for valid
+// addresses.  If ok is false, the address is invalid and the error value
+// may indicate why.
+func ValidA58(a58 []byte) (bool, error) {
+	var a A25
+	if err := a.Set58(a58); err != nil {
+		return false, err
+	}
+	if a.Version() != 0 {
+		return false, errors.New("not version 0")
+	}
+	return a.EmbeddedChecksum() == a.ComputeChecksum(), nil
+}
+
 // AddressFromPrivateKey takes a private key string and returns a Bitcoin address
 func AddressFromPrivateKey(privateKey string) (string, error) {
 	rawKey, err := PrivateKeyFromString(privateKey)
@@ -95,18 +113,40 @@ func AddressFromPubKey(publicKey *bsvec.PublicKey) (*bsvutil.LegacyAddressPubKey
 	return bsvutil.NewLegacyAddressPubKeyHash(bsvutil.Hash160(publicKey.SerializeCompressed()), &chaincfg.MainNetParams)
 }
 
-// ValidA58 validates a base58 encoded bitcoin address.  An address is valid
-// if it can be decoded into a 25 byte address, the version number is 0,
-// and the checksum validates.  Return value ok will be true for valid
-// addresses.  If ok is false, the address is invalid and the error value
-// may indicate why.
-func ValidA58(a58 []byte) (bool, error) {
-	var a A25
-	if err := a.Set58(a58); err != nil {
-		return false, err
+// AddressFromScript will take an output script and extract a standard bitcoin address
+func AddressFromScript(script string) (string, error) {
+
+	// No script?
+	if len(script) == 0 {
+		return "", errors.New("missing script")
 	}
-	if a.Version() != 0 {
-		return false, errors.New("not version 0")
+
+	// Decode the hex string into bytes
+	scriptBytes, err := hex.DecodeString(script)
+	if err != nil {
+		return "", err
 	}
-	return a.EmbeddedChecksum() == a.ComputeChecksum(), nil
+
+	// Extract the components from the script
+	var addresses []bsvutil.Address
+	_, addresses, _, err = txscript.ExtractPkScriptAddrs(scriptBytes, &chaincfg.MainNetParams)
+	if err != nil {
+		return "", err
+	}
+
+	// Missing an address?
+	if len(addresses) == 0 {
+		// This error case should not occur since the error above will occur when no address is found,
+		// however we ensure that we have an address for the NewLegacyAddressPubKeyHash() below
+		return "", fmt.Errorf("invalid output script, missing an address")
+	}
+
+	// Extract the address from the pubkey hash
+	var address *bsvutil.LegacyAddressPubKeyHash
+	if address, err = bsvutil.NewLegacyAddressPubKeyHash(addresses[0].ScriptAddress(), &chaincfg.MainNetParams); err != nil {
+		return "", err
+	}
+
+	// Use the encoded version of the address
+	return address.EncodeAddress(), nil
 }

address_test.go

@@ -177,3 +177,55 @@ func BenchmarkAddressFromPubKey(b *testing.B) {
 		_, _ = AddressFromPubKey(pubKey)
 	}
 }
+
+// TestAddressFromScript will test the method AddressFromScript()
+func TestAddressFromScript(t *testing.T) {
+	t.Parallel()
+
+	// Create the list of tests
+	var tests = []struct {
+		inputScript     string
+		expectedAddress string
+		expectedError   bool
+	}{
+		{"", "", true},
+		{"0", "", true},
+		{"76a914b424110292f4ea2ac92beb9e83cf5e6f0fa2996388ac", "1HRVqUGDzpZSMVuNSZxJVaB9xjneEShfA7", false},
+		{"76a914b424110292f4ea2ac92beb9e83cf5e6f0fa2", "", true},
+		{"76a914b424110292f4ea2ac92beb9e83", "", true},
+		{"76a914b424110292f", "", true},
+		{"1HRVqUGDzpZSMVuNSZxJVaB9xjneEShfA7", "", true},
+		{"514104cc71eb30d653c0c3163990c47b976f3fb3f37cccdcbedb169a1dfef58bbfbfaff7d8a473e7e2e6d317b87bafe8bde97e3cf8f065dec022b51d11fcdd0d348ac4410461cbdcc5409fb4b4d42b51d33381354d80e550078cb532a34bfa2fcfdeb7d76519aecc62770f5b0e4ef8551946d8a540911abe3e7854a26f39f58b25c15342af52ae", "", true},
+		{"410411db93e1dcdb8a016b49840f8c53bc1eb68a382e97b1482ecad7b148a6909a5cb2e0eaddfb84ccf9744464f82e160bfa9b8b64f9d4c03f999b8643f656b412a3", "", true},
+		{"47304402204e45e16932b8af514961a1d3a1a25fdf3f4f7732e9d624c6c61548ab5fb8cd410220181522ec8eca07de4860a4acdd12909d831cc56cbbac4622082221a8768d1d0901", "", true},
+	}
+
+	// Run tests
+	for _, test := range tests {
+		if address, err := AddressFromScript(test.inputScript); err != nil && !test.expectedError {
+			t.Errorf("%s Failed: [%v] inputted and error not expected but got: %s", t.Name(), test.inputScript, err.Error())
+		} else if err == nil && test.expectedError {
+			t.Errorf("%s Failed: [%v] inputted and error was expected", t.Name(), test.inputScript)
+		} else if address != test.expectedAddress {
+			t.Errorf("%s Failed: [%v] inputted [%s] expected but failed comparison of addresses, got: %s", t.Name(), test.inputScript, test.expectedAddress, address)
+		}
+	}
+}
+
+// ExampleAddressFromScript example using AddressFromScript()
+func ExampleAddressFromScript() {
+	address, err := AddressFromScript("76a914b424110292f4ea2ac92beb9e83cf5e6f0fa2996388ac")
+	if err != nil {
+		fmt.Printf("error occurred: %s", err.Error())
+		return
+	}
+	fmt.Printf("address found: %s", address)
+	// Output:address found: 1HRVqUGDzpZSMVuNSZxJVaB9xjneEShfA7
+}
+
+// BenchmarkAddressFromScript benchmarks the method AddressFromScript()
+func BenchmarkAddressFromScript(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_, _ = AddressFromScript("76a914b424110292f4ea2ac92beb9e83cf5e6f0fa2996388ac")
+	}
+}