Hex Packet Data (#144)

* add non-breaking event attribute

* CHANGELOG

* add migration doc

CHANGELOG.md

@@ -57,6 +57,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 ### Improvements
 
 * (modules/core/04-channel) [\#7949](https://github.com/cosmos/cosmos-sdk/issues/7949) Standardized channel `Acknowledgement` moved to its own file. Codec registration redundancy removed.
+* (modules/core/04-channel) [\#144](https://github.com/cosmos/ibc-go/pull/144) Introduced a `packet_data_hex` attribute to emit the hex-encoded packet data in events. This allows for raw binary (proto-encoded message) to be sent over events and decoded correctly on relayer. Original `packet_data` is DEPRECATED. All relayers and IBC event consumers are encouraged to switch to `packet_data_hex` as soon as possible.
 * (modules/light-clients/07-tendermint) [\#125](https://github.com/cosmos/ibc-go/pull/125) Implement efficient iteration of consensus states and pruning of earliest expired consensus state on UpdateClient.
 
 ## IBC in the Cosmos SDK Repository

docs/migrations/ibc-migration-043.md

@@ -99,3 +99,7 @@ The gRPC querier service endpoints have changed slightly. The previous files use
 Application developers need to update their `OnRecvPacket` callback logic. 
 
 The `OnRecvPacket` callback has been modified to only return the acknowledgement. The acknowledgement returned must implement the `Acknowledgement` interface. The acknowledgement should indicate if it represents a successful processing of a packet by returning true on `Success()` and false in all other cases. A return value of false on `Success()` will result in all state changes which occurred in the callback being discarded. More information can be found in the [documentation](https://github.com/cosmos/ibc-go/blob/main/docs/custom.md#receiving-packets).
+
+## IBC Event changes
+
+The `packet_data` attribute has been deprecated in favor of `packet_data_hex`, in order to provide standardized encoding/decoding of packet data in events. While the `packet_data` event still exists, all relayers and IBC Event consumers are strongly encouraged to switch over to using `packet_data_hex` as soon as possible.

modules/core/04-channel/keeper/packet.go

@@ -2,6 +2,7 @@ package keeper
 
 import (
 	"bytes"
+	"encoding/hex"
 	"fmt"
 	"time"
 
@@ -120,7 +121,8 @@ func (k Keeper) SendPacket(
 	ctx.EventManager().EmitEvents(sdk.Events{
 		sdk.NewEvent(
 			types.EventTypeSendPacket,
-			sdk.NewAttribute(types.AttributeKeyData, string(packet.GetData())),
+			sdk.NewAttribute(types.AttributeKeyData, string(packet.GetData())), // DEPRECATED
+			sdk.NewAttribute(types.AttributeKeyDataHex, hex.EncodeToString(packet.GetData())),
 			sdk.NewAttribute(types.AttributeKeyTimeoutHeight, timeoutHeight.String()),
 			sdk.NewAttribute(types.AttributeKeyTimeoutTimestamp, fmt.Sprintf("%d", packet.GetTimeoutTimestamp())),
 			sdk.NewAttribute(types.AttributeKeySequence, fmt.Sprintf("%d", packet.GetSequence())),
@@ -283,7 +285,8 @@ func (k Keeper) RecvPacket(
 	ctx.EventManager().EmitEvents(sdk.Events{
 		sdk.NewEvent(
 			types.EventTypeRecvPacket,
-			sdk.NewAttribute(types.AttributeKeyData, string(packet.GetData())),
+			sdk.NewAttribute(types.AttributeKeyData, string(packet.GetData())), // DEPRECATED
+			sdk.NewAttribute(types.AttributeKeyDataHex, hex.EncodeToString(packet.GetData())),
 			sdk.NewAttribute(types.AttributeKeyTimeoutHeight, packet.GetTimeoutHeight().String()),
 			sdk.NewAttribute(types.AttributeKeyTimeoutTimestamp, fmt.Sprintf("%d", packet.GetTimeoutTimestamp())),
 			sdk.NewAttribute(types.AttributeKeySequence, fmt.Sprintf("%d", packet.GetSequence())),
@@ -367,7 +370,8 @@ func (k Keeper) WriteAcknowledgement(
 	ctx.EventManager().EmitEvents(sdk.Events{
 		sdk.NewEvent(
 			types.EventTypeWriteAck,
-			sdk.NewAttribute(types.AttributeKeyData, string(packet.GetData())),
+			sdk.NewAttribute(types.AttributeKeyData, string(packet.GetData())), // DEPRECATED
+			sdk.NewAttribute(types.AttributeKeyDataHex, hex.EncodeToString(packet.GetData())),
 			sdk.NewAttribute(types.AttributeKeyTimeoutHeight, packet.GetTimeoutHeight().String()),
 			sdk.NewAttribute(types.AttributeKeyTimeoutTimestamp, fmt.Sprintf("%d", packet.GetTimeoutTimestamp())),
 			sdk.NewAttribute(types.AttributeKeySequence, fmt.Sprintf("%d", packet.GetSequence())),

modules/core/04-channel/types/events.go

@@ -20,7 +20,10 @@ const (
 	EventTypeAcknowledgePacket = "acknowledge_packet"
 	EventTypeTimeoutPacket     = "timeout_packet"
 
-	AttributeKeyData             = "packet_data"
+	// NOTE: DEPRECATED in favor of AttributeKeyDataHex
+	AttributeKeyData = "packet_data"
+
+	AttributeKeyDataHex          = "packet_data_hex"
 	AttributeKeyAck              = "packet_ack"
 	AttributeKeyTimeoutHeight    = "packet_timeout_height"
 	AttributeKeyTimeoutTimestamp = "packet_timeout_timestamp"