From a9ca02cbb0561bb4ae29cdc4e787bc209f8af100 Mon Sep 17 00:00:00 2001
From: Zhen Lu <ne.rwa.lz@gmail.com>
Date: Fri, 12 Jul 2024 17:39:32 -0700
Subject: [PATCH] Add a callback field. Parsing will return error if a required
 field is missing. (#38)

---
 uma/protocol/invoice.go    |  3 +++
 uma/test/protocol_test.go  |  3 ++-
 uma/test/tlv_utils_test.go | 24 ++++++++++++++++++++++++
 uma/utils/tlv_utils.go     |  6 +++++-
 4 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/uma/protocol/invoice.go b/uma/protocol/invoice.go
index 0c7b560..a9b2d17 100644
--- a/uma/protocol/invoice.go
+++ b/uma/protocol/invoice.go
@@ -65,6 +65,9 @@ type UmaInvoice struct {
 	// KYC status of the receiver, default is verified.
 	KycStatus *KycStatus `tlv:"11"`
 
+	// The callback url that the sender should send the PayRequest to.
+	Callback string `tlv:"12"`
+
 	// The signature of the UMA invoice
 	Signature *[]byte `tlv:"100"`
 }
diff --git a/uma/test/protocol_test.go b/uma/test/protocol_test.go
index a2964c4..7fb01b4 100644
--- a/uma/test/protocol_test.go
+++ b/uma/test/protocol_test.go
@@ -294,6 +294,7 @@ func TestUMAInvoiceTLVAndBech32(t *testing.T) {
 		SenderUma:           nil,
 		InvoiceLimit:        nil,
 		KycStatus:           &kyc,
+		Callback:            "https://example.com/callback",
 		Signature:           &signature,
 	}
 
@@ -307,5 +308,5 @@ func TestUMAInvoiceTLVAndBech32(t *testing.T) {
 
 	bech32String, err := invoice2.ToBech32String()
 	require.NoError(t, err)
-	require.Equal(t, "uma1qqxzgen0daqxyctj9e3k7mgpy33nwcesxanx2cedvdnrqvpdxsenzced8ycnve3dxe3nzvmxvv6xyd3evcusypp3xqcrqqcnqqp4256yqyy425eqg3hkcmrpwgpqzfqyqucnqvpsxqcrqpgpqyrpkcm0d4cxc6tpde3k2w3393jk6ctfdsarqtrwv9kk2w3squpnqt3npvqnxeqfwd5kwmnpw36hyega7x5zz", bech32String)
+	require.Equal(t, "uma1qqxzgen0daqxyctj9e3k7mgpy33nwcesxanx2cedvdnrqvpdxsenzced8ycnve3dxe3nzvmxvv6xyd3evcusypp3xqcrqqcnqqp4256yqyy425eqg3hkcmrpwgpqzfqyqucnqvpsxqcrqpgpqyrpkcm0d4cxc6tpde3k2w3393jk6ctfdsarqtrwv9kk2w3squpnqt3npvqnxrqudp68gurn8ghj7etcv9khqmr99e3k7mf0vdskcmrzv93kkeqfwd5kwmnpw36hyeg0e4m4j", bech32String)
 }
diff --git a/uma/test/tlv_utils_test.go b/uma/test/tlv_utils_test.go
index 229ab8f..efc8252 100644
--- a/uma/test/tlv_utils_test.go
+++ b/uma/test/tlv_utils_test.go
@@ -3,6 +3,7 @@ package uma_test
 import (
 	"testing"
 
+	"github.com/stretchr/testify/require"
 	"github.com/uma-universal-money-address/uma-go-sdk/uma/utils"
 )
 
@@ -28,6 +29,12 @@ type TLVUtilsTests struct {
 	OptionalEmptyStringField *string `tlv:"7"`
 }
 
+type TLVUtilsTestsMissingField struct {
+	StringField string `tlv:"0"`
+	IntField    int    `tlv:"1"`
+	BoolField   bool   `tlv:"2"`
+}
+
 func (d *TLVUtilsTests) MarshalTLV() ([]byte, error) {
 	return utils.MarshalTLV(d)
 }
@@ -161,3 +168,20 @@ func TestNestedTLVCoder(t *testing.T) {
 	}
 
 }
+
+func TestMissingFieldTLVCoder(t *testing.T) {
+	tlvUtilsTests := TLVUtilsTestsMissingField{
+		StringField: "hello",
+		IntField:    42,
+		BoolField:   true,
+	}
+
+	data, err := utils.MarshalTLV(&tlvUtilsTests)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var tlvUtilsTests2 TLVUtilsTests
+	err = utils.UnmarshalTLV(&tlvUtilsTests2, data)
+	require.Error(t, err)
+}
diff --git a/uma/utils/tlv_utils.go b/uma/utils/tlv_utils.go
index 7f19812..2a7303c 100644
--- a/uma/utils/tlv_utils.go
+++ b/uma/utils/tlv_utils.go
@@ -176,7 +176,11 @@ func UnmarshalTLV(v interface{}, data []byte) error {
 
 		content, ok := result[byte(tlv)]
 		if !ok {
-			continue
+			if field.Kind() == reflect.Ptr {
+				continue
+			} else {
+				return fmt.Errorf("missing TLV %d", tlv)
+			}
 		}
 
 		err = handle(field, content)