Custom JSON serialization of TipSetKey for array-of-CIDs (#756)

* Custom JSON serialization of TipSetKey for array-of-CIDs

* fixup! Custom JSON serialization of TipSetKey for array-of-CIDs

* fixup! Custom JSON serialization of TipSetKey for array-of-CIDs

certs/certs.go

@@ -46,7 +46,7 @@ type FinalityCertificate struct {
 	Signature []byte
 	// Changes between the power table used to validate this finality certificate and the power
 	// used to validate the next finality certificate. Sorted by ParticipantID, ascending.
-	PowerTableDelta PowerTableDiff
+	PowerTableDelta PowerTableDiff `json:"PowerTableDelta,omitempty"`
 }
 
 // NewFinalityCertificate constructs a new finality certificate from the given power delta (from

gpbft/chain.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"encoding/base32"
 	"encoding/binary"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"strings"
@@ -111,6 +112,68 @@ func (ts *TipSet) String() string {
 	return fmt.Sprintf("%s@%d", encTs[:min(16, len(encTs))], ts.Epoch)
 }
 
+// Custom JSON marshalling for TipSet to achieve:
+// 1. a standard TipSetKey representation that presents an array of dag-json CIDs.
+// 2. a commitment field that is a base64-encoded string.
+
+type tipSetSub TipSet
+type tipSetJson struct {
+	Key         []cid.Cid
+	Commitments []byte
+	*tipSetSub
+}
+
+func (ts TipSet) MarshalJSON() ([]byte, error) {
+	cids, err := cidsFromTipSetKey(ts.Key)
+	if err != nil {
+		return nil, err
+	}
+	return json.Marshal(&tipSetJson{
+		Key:         cids,
+		Commitments: ts.Commitments[:],
+		tipSetSub:   (*tipSetSub)(&ts),
+	})
+}
+
+func (ts *TipSet) UnmarshalJSON(b []byte) error {
+	aux := &tipSetJson{tipSetSub: (*tipSetSub)(ts)}
+	var err error
+	if err = json.Unmarshal(b, &aux); err != nil {
+		return err
+	}
+	if ts.Key, err = tipSetKeyFromCids(aux.Key); err != nil {
+		return err
+	}
+	if len(aux.Commitments) != 32 {
+		return errors.New("commitments must be 32 bytes")
+	}
+	copy(ts.Commitments[:], aux.Commitments)
+	return nil
+}
+
+func cidsFromTipSetKey(encoded []byte) ([]cid.Cid, error) {
+	var cids []cid.Cid
+	for nextIdx := 0; nextIdx < len(encoded); {
+		nr, c, err := cid.CidFromBytes(encoded[nextIdx:])
+		if err != nil {
+			return nil, err
+		}
+		cids = append(cids, c)
+		nextIdx += nr
+	}
+	return cids, nil
+}
+
+func tipSetKeyFromCids(cids []cid.Cid) (TipSetKey, error) {
+	var buf bytes.Buffer
+	for _, c := range cids {
+		if _, err := buf.Write(c.Bytes()); err != nil {
+			return nil, err
+		}
+	}
+	return buf.Bytes(), nil
+}
+
 // A chain of tipsets comprising a base (the last finalised tipset from which the chain extends).
 // and (possibly empty) suffix.
 // Tipsets are assumed to be built contiguously on each other,

gpbft/chain_test.go

@@ -1,9 +1,12 @@
 package gpbft_test
 
 import (
+	"bytes"
+	"encoding/json"
 	"testing"
 
 	"github.com/filecoin-project/go-f3/gpbft"
+	"github.com/ipfs/go-cid"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -184,3 +187,105 @@ func TestECChain_Eq(t *testing.T) {
 		})
 	}
 }
+
+func TestTipSetSerialization(t *testing.T) {
+	t.Parallel()
+	var (
+		c1        = gpbft.MakeCid([]byte("barreleye1"))
+		c2        = gpbft.MakeCid([]byte("barreleye2"))
+		c3        = gpbft.MakeCid([]byte("barreleye3"))
+		testCases = []gpbft.TipSet{
+			{
+				Epoch:       1,
+				Key:         append(append(c1.Bytes(), c2.Bytes()...), c3.Bytes()...),
+				PowerTable:  gpbft.MakeCid([]byte("fish")),
+				Commitments: [32]byte{0x01},
+			},
+			{
+				Epoch:       101,
+				Key:         c1.Bytes(),
+				PowerTable:  gpbft.MakeCid([]byte("lobster")),
+				Commitments: [32]byte{0x02},
+			},
+		}
+		badJsonEncodable = []struct {
+			ts  gpbft.TipSet
+			err string
+		}{
+			{
+				ts: gpbft.TipSet{
+					Epoch:       1,
+					Key:         []byte("nope"),
+					PowerTable:  gpbft.MakeCid([]byte("fish")),
+					Commitments: [32]byte{0x01},
+				},
+				err: "invalid cid",
+			},
+		}
+		badJsonDecodable = []struct {
+			json string
+			err  string
+		}{
+			{
+				json: `{"Key":["nope"],"Commitments":"AgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=","Epoch":101,"PowerTable":{"/":"bafy2bzaced5zqzzbxzyzuq2tcxhuclnvdn3y6ijhurgaapnbayul2dd5gspc4"}}`,
+				err:  "invalid cid",
+			},
+			{
+				json: `{"Key":[{"/":"bafy2bzacecp4qqs334yrvzxsnlolskbtvyc3ub7k5tzx4s2m77vimzzkduj3g"}],"Commitments":"bm9wZQ==","Epoch":101,"PowerTable":{"/":"bafy2bzaced5zqzzbxzyzuq2tcxhuclnvdn3y6ijhurgaapnbayul2dd5gspc4"}}`,
+				err:  "32 bytes",
+			},
+		}
+	)
+
+	t.Run("cbor round trip", func(t *testing.T) {
+		req := require.New(t)
+		for _, ts := range testCases {
+			var buf bytes.Buffer
+			req.NoError(ts.MarshalCBOR(&buf))
+			t.Logf("cbor: %x", buf.Bytes())
+			var rt gpbft.TipSet
+			req.NoError(rt.UnmarshalCBOR(&buf))
+			req.Equal(ts, rt)
+		}
+	})
+
+	t.Run("json round trip", func(t *testing.T) {
+		req := require.New(t)
+		for _, ts := range testCases {
+			data, err := ts.MarshalJSON()
+			req.NoError(err)
+			t.Logf("json: %s", data)
+			var rt gpbft.TipSet
+			req.NoError(rt.UnmarshalJSON(data))
+			req.Equal(ts, rt)
+
+			// check that we serialized the CIDs in the standard dag-json form
+			var bareMap map[string]any
+			req.NoError(json.Unmarshal(data, &bareMap))
+			keyField, ok := bareMap["Key"].([]any)
+			req.True(ok)
+			req.Len(keyField, len(ts.Key)/38)
+			for j, c := range []cid.Cid{c1, c2, c3}[:len(ts.Key)/38] {
+				req.Equal(map[string]any{"/": c.String()}, keyField[j])
+			}
+
+			// check that the supplemental data is a base64 string
+			commitField, ok := bareMap["Commitments"].(string)
+			req.True(ok)
+			req.Len(commitField, 44)
+		}
+	})
+
+	t.Run("json error cases", func(t *testing.T) {
+		req := require.New(t)
+		for i, tc := range badJsonEncodable {
+			_, err := tc.ts.MarshalJSON()
+			req.ErrorContains(err, tc.err, "expected error for test case %d", i)
+		}
+		for i, tc := range badJsonDecodable {
+			var ts gpbft.TipSet
+			err := ts.UnmarshalJSON([]byte(tc.json))
+			req.ErrorContains(err, tc.err, "expected error for test case %d", i)
+		}
+	})
+}

gpbft/gpbft.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/binary"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"math"
@@ -94,6 +95,35 @@ func (d *SupplementalData) Eq(other *SupplementalData) bool {
 	return d.Commitments == other.Commitments && d.PowerTable == other.PowerTable
 }
 
+// Custom JSON marshalling for SupplementalData to achieve a commitment field
+// that is a base64-encoded string.
+
+type supplementalDataSub SupplementalData
+type supplementalDataJson struct {
+	Commitments []byte
+	*supplementalDataSub
+}
+
+func (sd SupplementalData) MarshalJSON() ([]byte, error) {
+	return json.Marshal(&supplementalDataJson{
+		Commitments:         sd.Commitments[:],
+		supplementalDataSub: (*supplementalDataSub)(&sd),
+	})
+}
+
+func (sd *SupplementalData) UnmarshalJSON(b []byte) error {
+	aux := &supplementalDataJson{supplementalDataSub: (*supplementalDataSub)(sd)}
+	var err error
+	if err = json.Unmarshal(b, &aux); err != nil {
+		return err
+	}
+	if len(aux.Commitments) != 32 {
+		return errors.New("commitments must be 32 bytes")
+	}
+	copy(sd.Commitments[:], aux.Commitments)
+	return nil
+}
+
 // Fields of the message that make up the signature payload.
 type Payload struct {
 	// GossiPBFT instance (epoch) number.

gpbft/gpbft_test.go

@@ -3,6 +3,7 @@ package gpbft_test
 import (
 	"bytes"
 	"crypto/rand"
+	"encoding/json"
 	"io"
 	"testing"
 
@@ -1734,3 +1735,57 @@ func TestGPBFT_Sway(t *testing.T) {
 		require.Fail(t, "after 10 tries did not swayed to proposals 1 and 2 at CONVERGE and COMMIT, respectively.")
 	})
 }
+
+func TestSupplementalDataSerialization(t *testing.T) {
+	t.Parallel()
+	var (
+		testCases = []gpbft.SupplementalData{
+			{
+				PowerTable:  gpbft.MakeCid([]byte("fish")),
+				Commitments: [32]byte{0x01},
+			},
+			{
+				PowerTable:  gpbft.MakeCid([]byte("lobster")),
+				Commitments: [32]byte{0x02},
+			},
+		}
+	)
+
+	t.Run("cbor round trip", func(t *testing.T) {
+		req := require.New(t)
+		for _, ts := range testCases {
+			var buf bytes.Buffer
+			req.NoError(ts.MarshalCBOR(&buf))
+			t.Logf("cbor: %x", buf.Bytes())
+			var rt gpbft.SupplementalData
+			req.NoError(rt.UnmarshalCBOR(&buf))
+			req.Equal(ts, rt)
+		}
+	})
+
+	t.Run("json round trip", func(t *testing.T) {
+		req := require.New(t)
+		for _, ts := range testCases {
+			data, err := ts.MarshalJSON()
+			req.NoError(err)
+			t.Logf("json: %s", data)
+			var rt gpbft.SupplementalData
+			req.NoError(rt.UnmarshalJSON(data))
+			req.Equal(ts, rt)
+
+			// check that the supplemental data is a base64 string
+			var bareMap map[string]any
+			req.NoError(json.Unmarshal(data, &bareMap))
+			commitField, ok := bareMap["Commitments"].(string)
+			req.True(ok)
+			req.Len(commitField, 44)
+		}
+	})
+
+	t.Run("json error cases", func(t *testing.T) {
+		req := require.New(t)
+		var ts gpbft.SupplementalData
+		err := ts.UnmarshalJSON([]byte(`{"Commitments":"bm9wZQ==","PowerTable":{"/":"bafy2bzaced5zqzzbxzyzuq2tcxhuclnvdn3y6ijhurgaapnbayul2dd5gspc4"}}`))
+		req.ErrorContains(err, "32 bytes")
+	})
+}