slashing types incompatibility between v45 provider and v47 consumer

[MSalopek]

Problem

During testing it was discovered that an incompatibility exists between ICS <= v2.0.0 and ICS v3 release candidates.

The incompatibility arises from the fact that ICS v3 uses cosmos-sdk slashing proto definitions, whereas ICS <= v2 uses custom proto definitions.

For ICS v3 this is the Infraction enum used:

// Infraction indicates the infraction a validator commited.
enum Infraction {
  // UNSPECIFIED defines an empty infraction.
  INFRACTION_UNSPECIFIED = 0;
  // DOUBLE_SIGN defines a validator that double-signs a block.
  INFRACTION_DOUBLE_SIGN = 1;
  // DOWNTIME defines a validator that missed signing too many blocks.
  INFRACTION_DOWNTIME = 2;
}

ICS <= v2 uses a slightly different definition:

// InfractionType indicates the infraction type a validator commited.
enum InfractionType {
  option (gogoproto.goproto_enum_prefix) = false;

  // UNSPECIFIED defines an empty infraction type.
  INFRACTION_TYPE_UNSPECIFIED = 0 [(gogoproto.enumvalue_customname) = "InfractionEmpty"];
  // DOUBLE_SIGN defines a validator that double-signs a block.
  INFRACTION_TYPE_DOUBLE_SIGN = 1 [(gogoproto.enumvalue_customname) = "DoubleSign"];
  // DOWNTIME defines a validator that missed signing too many blocks.
  INFRACTION_TYPE_DOWNTIME = 2 [(gogoproto.enumvalue_customname) = "Downtime"];
}

This difference makes the ICS v2 provider (cosmos-sdk v45, ibc-go v4) unable to process slash packets coming from ICS v3-rc consumer (cosmos-sdk v47, ibc-go v7).

The changes are not state breaking since the underlying structure stored on chain is the same (both are INT). When sending packets, the structures get marshalled into different JSON strings causing an error when the slashes are processed on the provider. The provider cannot unmarshal the Slash packet Infraction enum.

ICS <= v2 (cosmos-sdk v45, ibc-go v4):

{
    "type": "CONSUMER_PACKET_TYPE_SLASH",
    "slashPacketData": {
        "validator": {
            "address": "",
            "power": "1"
        },
        "valset_update_id": "1",
        "infraction": "INFRACTION_TYPE_DOWNTIME"
    }
}

ICS v3-rc (cosmos-sdk v47, ibc-go v7):

{
    "type": "CONSUMER_PACKET_TYPE_SLASH",
    "slashPacketData": {
        "validator": {
            "address": "",
            "power": "1"
        },
        "valset_update_id": "1",
        "infraction": "INFRACTION_DOWNTIME"
    }
}

Closing criteria

Address the issue by conforming to the infraction proto/json type used by the earlier versions of ICS so the protocol communication over the wire is not hindered.

Possible solutions:

• use new features in protobuf enum values should have json_name pseudo-option just like fields protocolbuffers/protobuf#4328

Problem details

Details available on cosmos-sdk:

• fix(staking): make staking Infraction consistent with v45-ics cosmos-sdk#16742
• Infraction enum changed in cosmos-sdk v0.47.x with respect to v0.45.x-ics cosmos-sdk#16740

[shaspitz]

This all looks great, thanks! Quick comment that from my knowledge the test was ran with gaia v10 which references ICS v1.1.0-multiden, not v2. Also the v1 proto definitions still come from sdk (45 branch), it's just a different proto definition there

[MSalopek]

Updated parts of the issue that did not state that the compatibility must be maintainer for ICS <= v2. That includes both v1 and v2. Thanks for pointing it out!