From 2d70a30aa95dd9e8515a4e4256d67f825b8e9e7b Mon Sep 17 00:00:00 2001
From: Aurora Gaffney <aurora@agaffney.org>
Date: Wed, 12 Jul 2023 21:31:53 -0500
Subject: [PATCH] feat: support for CBOR tags for arbitrarily large ints

Fixes #360
---
 cbor/value.go      | 19 ++++++++++++++++++-
 cbor/value_test.go | 16 ++++++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/cbor/value.go b/cbor/value.go
index a9f75514..fa14236b 100644
--- a/cbor/value.go
+++ b/cbor/value.go
@@ -18,6 +18,7 @@ import (
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
+	"math/big"
 	"sort"
 	"strings"
 )
@@ -94,7 +95,17 @@ func (v *Value) UnmarshalCBOR(data []byte) error {
 					value:       &newValue,
 				}
 			} else {
-				return fmt.Errorf("unsupported CBOR tag: %d", tmpTag.Number)
+				// Fall back to standard CBOR tag parsing for our supported types
+				var tmpTagDecode interface{}
+				if _, err := Decode(data, &tmpTagDecode); err != nil {
+					return err
+				}
+				switch tmpTagDecode.(type) {
+				case int, uint, int64, uint64, bool, big.Int:
+					v.value = tmpTagDecode
+				default:
+					return fmt.Errorf("unsupported CBOR tag number: %d", tmpTag.Number)
+				}
 			}
 		}
 	default:
@@ -218,6 +229,12 @@ func generateAstJson(obj interface{}) ([]byte, error) {
 		return []byte(tmpJson), nil
 	case Constructor:
 		return json.Marshal(obj)
+	case big.Int:
+		tmpJson := fmt.Sprintf(
+			`{"int":%s}`,
+			v.String(),
+		)
+		return []byte(tmpJson), nil
 	case int, uint, uint64, int64:
 		tmpJsonObj["int"] = v
 	case bool:
diff --git a/cbor/value_test.go b/cbor/value_test.go
index ecb19d7a..4ad92192 100644
--- a/cbor/value_test.go
+++ b/cbor/value_test.go
@@ -18,6 +18,7 @@ import (
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
+	"math/big"
 	"reflect"
 	"strings"
 	"testing"
@@ -70,6 +71,15 @@ var testDefs = []struct {
 		},
 		expectedAstJson: `{"map":[{"k":{"int":1},"v":{"list":[{"int":2}]}},{"k":{"int":3},"v":{"list":[{"int":4}]}}]}`,
 	},
+	// [22318265904693663008365, 8535038193994223137511702528]
+	{
+		cborHex: "82C24A04B9E028911409DC866DC24C1B9404A39BD8000000000000",
+		expectedObject: []any{
+			*(new(big.Int).SetBytes(test.DecodeHexString("04B9E028911409DC866D"))),
+			*(new(big.Int).SetBytes(test.DecodeHexString("1B9404A39BD8000000000000"))),
+		},
+		expectedAstJson: `{"list":[{"int":22318265904693663008365},{"int":8535038193994223137511702528}]}`,
+	},
 }
 
 func TestValueDecode(t *testing.T) {
@@ -198,6 +208,12 @@ func TestLazyValueMarshalJSON(t *testing.T) {
 			strings.ToLower(testDef.cborHex),
 			testDef.expectedAstJson,
 		)
+		if testDef.expectedObject == nil {
+			fullExpectedJson = fmt.Sprintf(
+				`{"cbor":"%s"}`,
+				strings.ToLower(testDef.cborHex),
+			)
+		}
 		if !test.JsonStringsEqual(jsonData, []byte(fullExpectedJson)) {
 			t.Fatalf("CBOR did not marshal to expected JSON\n  got: %s\n  wanted: %s", jsonData, fullExpectedJson)
 		}