Go Stellar Base

STATUS: This library is currently in alpha testing. It has support reading/writing xdr, and can sign and hash byte slices in accordance with the stellar protocol, but does not yet have the necessary helpers to make constructing valid transactions easy.

The stellar-base library is the lowest-level stellar helper library. It consists of classes to read, write, hash, and sign the xdr structures that are used in stellar-core.

Installation

go get github.com/stellar/go-stellar-base

Usage

Let's first decode a transaction (taken from stellar-core's txhistory table):

func ExampleDecodeTransaction() {
	data := "rqN6LeOagjxMaUP96Bzfs9e0corNZXzBWJkFoK7kvkwAAAAKAAAAAwAAAAEAAAAAAAA" +
		"AAAAAAAEAAAAAAAAAAW5oJtVdnYOVdZqtXpTHBtbcY0mCmfcBIKEgWnlvFIhaAAAAAA" +
		"AAAAAC+vCAAAAAAa6jei0gQGmrUfm+o2CMv/w32YzJgGYlmgG6CUW3FwyD6AZ/5TtPZ" +
		"qEt9kyC3GJeXfzoS667ZPhPUSNjSWgAeDPHFLcM"

	rawr := strings.NewReader(data)
	b64r := base64.NewDecoder(base64.StdEncoding, rawr)

	var tx xdr.TransactionEnvelope
	bytesRead, err := xdr.Unmarshal(b64r, &tx)

	fmt.Printf("read %d bytes\n", bytesRead)

	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("This tx has %d operations\n", len(tx.Tx.Operations))
	// Output: read 180 bytes
	// This tx has 1 operations
}

Now, the low-level creation of a TransactionEnvelope:

// ExampleLowLevelTransaction creates and signs a simple transaction, and then
// encodes it into a hex string capable of being submitted to stellar-core.
//
// It uses the low-level xdr facilities to create the transaction.
func ExampleLowLevelTransaction() {
	spub, spriv, err := GenerateKeyFromSeed("SDOTALIMPAM2IV65IOZA7KZL7XWZI5BODFXTRVLIHLQZQCKK57PH5F3H")

	if err != nil {
		log.Fatal(err)
	}

	dpub, _, err := GenerateKeyFromSeed("sfkPCKA6XgaeHZH3NE57i3QrjVcw61c1noWQCgnHa6KJP2BrbXD")

	if err != nil {
		log.Fatal(err)
	}

	op := xdr.PaymentOp{
		Destination: dpub.KeyData(),
		Currency:    xdr.NewCurrencyCurrencyTypeNative(),
		Amount:      50 * 10000000,
	}

	tx := xdr.Transaction{
		SourceAccount: spub.KeyData(),
		Fee:           10,
		SeqNum:        xdr.SequenceNumber(1),
		Memo:          xdr.NewMemoMemoNone(),
		Operations: []xdr.Operation{
			{Body: xdr.NewOperationBodyPayment(op)},
		},
	}

	var txBytes bytes.Buffer
	_, err = xdr.Marshal(&txBytes, tx)
	if err != nil {
		log.Fatal(err)
	}

	txHash := Hash(txBytes.Bytes())
	signature := spriv.Sign(txHash[:])

	ds := xdr.DecoratedSignature{
		Hint:      spriv.Hint(),
		Signature: xdr.Uint512(signature),
	}

	txe := xdr.TransactionEnvelope{
		Tx:         tx,
		Signatures: []xdr.DecoratedSignature{ds},
	}

	var txeBytes bytes.Buffer
	_, err = xdr.Marshal(&txeBytes, txe)
	if err != nil {
		log.Fatal(err)
	}

	txeHex := hex.EncodeToString(txeBytes.Bytes())

	fmt.Printf("tx hex: %s", txeHex)
	// Output: tx hex: 3658fe7598d20c7a6de3297f84bc52bd2a1ec8c0f1f6c5b41cc1c7571b4331f00000000a000000000000000100000000000000000000000100000000000000012d24692ed08bbf679ba199448870d2191e876fecd92fdd9f6d274da4e6de134100000000000000001dcd650000000001dd302d0c0cee527cf02f6a0aec6916966298712914c63e3c57de74a6e27c29ea234a555fcc36533417afe4e1147815a42529fbca3429bc7caf0a06dc6b383ca6e9d4d80f
}