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x/ccv/consumer

Overview​

The ICS consumer module enables consumer chains to use stake locked on a provider chain as collateral for their own proof-of-stake based block production.

The consumer module established a IBC ordered channel to the provider chain. This channel is used by the provider chain to regularly send validator updates to the consumer chain. The consumer sends these updates to its own consensus engine. This means that the consumer module acts as a staking module of the consumer chain.

Regularly, the consumer module sends a part of the consumer chain's block rewards to the provider chain as ICS rewards.

If one of the validators in the consumer chain's validator set is missing enough blocks (i.e., downtime infraction), the consumer module notifies the provider chain by sending an IBC packet to the provider module. As a result, the misbehaving validator is punished on the provider chain.

State​

For clarity, the description of the consumer module state is split into features. For a more accurate description, check out the x/ccv/consumer/types/keys.go file, which contains the definitions of all the keys.

Provider Connection​

ProviderClientID​

ProviderClientID is the ID of the provider client on which the CCV channel is built.

Format: byte(3) -> string

ProviderChannelID​

ProviderChannelID is the ID of the CCV channel.

Format: byte(4) -> string

Changeover​

PreCCV​

PreCCV is the flag set when the consumer chain is in the process of a standalone to consumer chain changeover.

Format: byte(7) -> uint64

InitialValSet​

InitialValSet is the initial validator set on the consumer chain.

Format: byte(8) -> GenesisState

Note that only the InitialValSet field of the ProviderInfo field of GenesisState is set, i.e.,

message GenesisState {
  ...
  ProviderInfo provider = 14
      [ (gogoproto.nullable) = false ];
}

message ProviderInfo {
  // InitialValset filled in on new chain and on restart.
  repeated .tendermint.abci.ValidatorUpdate initial_val_set = 3
      [ (gogoproto.nullable) = false ];
}

InitGenesisHeight​

InitGenesisHeight is the height when the consumer module was initialized (i.e., the InitGenesis method was called).

Format: byte(17) -> uint64

PrevStandaloneChain​

PrevStandaloneChain is the flag set when the consumer chain was previously a standalone chain.

Format: byte(19) -> []byte{}

Validator Updates​

PendingChanges​

PendingChanges are the validator updates received from the provider that were not yet sent to the consensus engine.

Format: byte(5) -> ValidatorSetChangePacketData

Note that only the ValidatorUpdates field of ValidatorSetChangePacketData is set.

CrossChainValidator​

CrossChainValidator is the internal state of a consumer validator with consensus address addr.

Format: byte(16) | addr -> CrossChainValidator, where CrossChainValidator is defined as

message CrossChainValidator {
  bytes address = 1;
  int64 power = 2;
  // pubkey is the consensus public key of the validator, as a Protobuf Any.
  google.protobuf.Any pubkey = 3 [
    (cosmos_proto.accepts_interface) = "cosmos.crypto.PubKey",
    (gogoproto.moretags) = "yaml:\"consensus_pubkey\""
  ];
  // deprecated
  bool opted_out = 4 [deprecated = true];
}

HistoricalInfo​

HistoricalInfo is the header and validator information for a given block. For more details, see the Cosmos SDK docs.

Format: byte(11) | height -> HistoricalInfo, where HistoricalInfo is defined in the staking module as

message HistoricalInfo {
  tendermint.types.Header header = 1 [(gogoproto.nullable) = false, (amino.dont_omitempty) = true];
  repeated Validator      valset = 2 [(gogoproto.nullable) = false, (amino.dont_omitempty) = true];
}

Reward Distribution​

LastDistributionTransmission​

LastDistributionTransmission is the block height of the last attempt to send ICS rewards to the provider module.

Format: byte(1) -> LastTransmissionBlockHeight, where LastTransmissionBlockHeight is defined as

message LastTransmissionBlockHeight { 
  int64 height = 1; 
}

Downtime Infractions​

OutstandingDowntime​

OutstandingDowntime is the flag set when a SlashPacket is queued to be sent to the provider for a downtime infraction of a validator with consensus address addr. The flag is unset when receiving from the provider a VSCPacket with a slash acknowledgement (see SlashAcks in ValidatorSetChangePacketData).

Format: byte(14) | addr -> []byte{}

HeightValsetUpdateID​

HeightValsetUpdateID is the validator set update ID associated with a block height.

Format: byte(13) | height -> uint64

PendingPacketsIndex​

PendingPacketsIndex is the next index available to store packet data to be sent to the provider chain (see below).

Format: byte(20) -> uint64

PendingDataPacketsV1​

PendingDataPacketsV1 is the queue of packet data to be sent to the provider chain. In general, packets in this queue will be sent to the provider in the end blocker, unless

  • the CCV channel is not yet established;
  • the provider client is expired;
  • the last slash packet sent was not yet acknowledged by the provider chain.

Format: byte(15) | index -> ConsumerPacketData, where index is the index of the packet in the queue and ConsumerPacketData is defined as

message ConsumerPacketData {
  ConsumerPacketDataType type = 1;

  oneof data {
    SlashPacketData slashPacketData = 2;
    VSCMaturedPacketData vscMaturedPacketData = 3;
  }
}

SlashRecord​

SlashRecord is the record storing the state of a SlashPacket sent to the provider chain that was not yet acknowledged. See ADR 008 for more details.

Format: byte(21) -> SlashRecord, where SlashRecord is defined as

message SlashRecord {
  bool waiting_on_reply = 1;
  google.protobuf.Timestamp send_time = 2
      [ (gogoproto.stdtime) = true, (gogoproto.nullable) = false ];
}

State Transitions​

TBA

IBC Callbacks​

The consumer module is an IBC application that implements the IBC module callback.

OnChanOpenInit​

OnChanOpenInit first verifies that the CCV channel was not already created. Then, it validates the channel parameters -- an ordered IBC channel connected on the consumer port and with the counterparty port set to provider -- and asserts that the version matches the expected version (only version 1 is supported).

Finally, it verifies that the underlying client is the expected client of the provider chain (i.e., provided in the consumer module genesis state).

OnChanOpenTry​

OnChanOpenTry returns an error. MsgChannelOpenTry should be sent to the provider.

OnChanOpenAck​

OnChanOpenAck first verifies that the CCV channel was not already created. Then it verifies that the counterparty version matches the expected version (only version 1 is supported).

If the verification passes, it stores the ProviderFeePoolAddr in the state.

Finally, if the DistributionTransmissionChannel parameter is not set, it initiates the opening handshake for a token transfer channel over the same connection as the CCV channel by calling the ChannelOpenInit method of the IBC module.

OnChanOpenConfirm​

OnChanOpenConfirm returns an error. MsgChanOpenConfirm should be sent to the provider.

OnChanCloseInit​

OnChanCloseInit allows relayers to close duplicate OPEN channels, if the channel handshake is completed.

OnChanCloseConfirm​

OnChanCloseConfirm is a no-op.

OnRecvPacket​

OnRecvPacket unmarshals the IBC packet data into a ValidatorSetChangePacketData struct (see below) and executes the handling logic.

  • If it is the first packet received, sets the underlying IBC channel as the canonical CCV channel.
  • Collects validator updates to be sent to the consensus engine at the end of the block.
  • Store in state the block height to VSC id (i.e., valset_update_id) mapping.
  • Removed the outstanding downtime flags from the validator for which the jailing for downtime infractions was acknowledged by the provider chain (see the slash_acks field in ValidatorSetChangePacketData).
message ValidatorSetChangePacketData {
  repeated .tendermint.abci.ValidatorUpdate validator_updates = 1 [
    (gogoproto.nullable) = false,
    (gogoproto.moretags) = "yaml:\"validator_updates\""
  ];
  uint64 valset_update_id = 2;
  // consensus address of consumer chain validators
  // successfully jailed on the provider chain
  repeated string slash_acks = 3;
}

OnAcknowledgementPacket​

OnAcknowledgementPacket enables the consumer module to confirm that the provider module received the previously sent SlashPacket and it unblocks the sending of the next SlashPacket. This functionality is needed for throttling jailing on the provider chain. For more details, see ADR-008.

OnTimeoutPacket​

OnTimeoutPacket is a no-op.

Messages​

MsgUpdateParams​

MsgUpdateParams updates the consumer module parameters. The params are updated through a governance proposal where the signer is the gov module account address.

message MsgUpdateParams {
  option (cosmos.msg.v1.signer) = "authority";

  // signer is the address of the governance account.
  string authority = 1 [(cosmos_proto.scalar) = "cosmos.AddressString"];

  // params defines the x/consumer parameters to update.
  interchain_security.ccv.v1.ConsumerParams params = 2 [(gogoproto.nullable) = false];
}

BeginBlock​

In the BeginBlock of the consumer module the following actions are performed:

  • Store in state the block height to VSC id mapping needed for sending to the provider the height of infractions committed on the consumer chain.
  • Track historical entries. This is the same logic as in the x/staking module.

EndBlock​

In the EndBlock of the consumer module the following actions are performed:

  • If PreCCV state is active, i.e., the consumer chain is a previously standalone chain that was just upgraded to include the consumer module, then execute the changeover logic.
  • Otherwise, distribute block rewards internally and once every BlocksPerDistributionTransmission send ICS rewards to the provider chain.
  • Send slash packets to the provider chain reporting infractions validators committed on the consumer chain.
  • Send to the consensus engine validator updates reveived from the provider chain.

Hooks​

TBA

Events​

TBA

Parameters​

warning

The consumer module parameters are set by the provider when creating the consumer genesis (i.e., when launching the consumer chain). As a result, changes of these parameters might result in incompatibilities between different versions of consumers and providers.

The consumer module contains the following parameters.

Enabled​

Enabled is deprecated.

BlocksPerDistributionTransmission​

TypeDefault value
int641000

BlocksPerDistributionTransmission is the number of blocks between rewards transfers from the consumer to the provider.

DistributionTransmissionChannel​

TypeDefault value
string""

DistributionTransmissionChannel is the provider chain IBC channel used for receiving consumer chain reward distribution token transfers. This is automatically set during the consumer-provider handshake procedure.

Providing an IBC transfer channel enables a consumer chain to re-use one of the existing channels to the provider for consumer chain rewards distribution. This will preserve the ibc denom that may already be in use. This is especially important for standalone chains transitioning to become consumer chains. For more details, see the changeover procedure.

ProviderFeePoolAddrStr​

TypeDefault value
string""

ProviderFeePoolAddrStr is the provider chain fee pool address used for receiving consumer chain reward distribution token transfers. This is automatically set during the consumer-provider handshake procedure.

CcvTimeoutPeriod​

TypeDefault value
time.Duration2419200s (4 weeks)

CcvTimeoutPeriod is the period used to compute the timeout timestamp when sending IBC packets. CcvTimeoutPeriod may have different values on the provider and consumer chains.

TransferTimeoutPeriod​

TypeDefault value
time.Duration3600s (1 hour)

TransferTimeoutPeriod is the timeout period for consumer chain reward distribution IBC packets.

ConsumerRedistributionFraction​

TypeDefault value
string"0.75"

ConsumerRedistributionFraction is the fraction of tokens allocated to the consumer redistribution address during distribution events. The fraction is a string representing a decimal number. For example "0.75" would represent 75%. For example, a consumer with ConsumerRedistributionFraction set to "0.75" would send 75% of its block rewards and accumulated fees to the consumer redistribution address, and the remaining 25% to the provider chain every BlocksPerDistributionTransmission blocks.

HistoricalEntries​

TypeDefault value
int6410000

HistoricalEntries is the number of historical info entries to persist in store (see the staking module parameter with the same name for details). HistoricalEntries is needed since the consumer module acts as a staking module on the consumer chain.

UnbondingPeriod​

TypeDefault value
time.Duration1209600s (2 weeks)

UnbondingPeriod is the unbonding period on the consumer chain. It is recommended that every consumer chain set and unbonding period shorter than provider unbonding period, e.g., one week shorter.

SoftOptOutThreshold​

SoftOptOutThreshold is deprecated.

RewardDenoms​

TypeDefault value
[]string[]string

RewardDenoms are the denominations which are allowed to be sent to the provider as ICS rewards.

ProviderRewardDenoms​

TypeDefault value
[]string[]string

ProviderRewardDenoms are the denominations coming from the provider which are allowed to be used as ICS rewards. e.g. "uatom".

RetryDelayPeriod​

TypeDefault value
time.Duration3600s (1 hour)

RetryDelayPeriod is the period at which the consumer retries to send a SlashPacket that was rejected by the provider. For more details, see ADR-008.

Client​

CLI​

A user can interact with the consumer module using the CLI.

Query​

The query commands allow users to query consumer state.

interchain-security-cd query ccvconsumer --help
Next Fee Distribution​

The next-fee-distribution command allows to query next fee distribution data.

interchain-security-cd query ccvconsumer next-fee-distribution [flags]
Example
interchain-security-cd query ccvconsumer next-fee-distribution

Output:

data:
  currentHeight: "967"
  distribution_fraction: "0.75"
  lastHeight: "960"
  nextHeight: "980"
  toConsumer: ""
  toProvider: ""
  total: ""
Provider Info​

The provider-info command allows to query provider info.

interchain-security-cd query ccvconsumer provider-info [flags]
Example
interchain-security-cd query ccvconsumer provider-info

Output:

consumer:
  chainID: pion-1
  channelID: channel-0
  clientID: 07-tendermint-0
  connectionID: connection-0
provider:
  chainID: provider
  channelID: channel-0
  clientID: 07-tendermint-0
  connectionID: connection-0
Throttle State​

The throttle-state command allows to query on-chain state relevant with slash packet throttling.

interchain-security-cd query ccvconsumer throttle-state [flags]
Example
interchain-security-cd query ccvconsumer throttle-state

Output:

packet_data_queue:
- slashPacketData:
    infraction: INFRACTION_DOWNTIME
    validator:
      address: mb06cu8SzQJOdYSzrJAK43Q8at8=
      power: "500"
    valset_update_id: "48"
  type: CONSUMER_PACKET_TYPE_SLASH
slash_record:
  send_time: "2024-10-02T07:58:24.405645924Z"
  waiting_on_reply: true
Params​

The params command allows to query consumer module parameters.

interchain-security-cd query ccvconsumer params [flags]
Example
interchain-security-cd query ccvconsumer params

Output:

params:
  blocks_per_distribution_transmission: "1000"
  ccv_timeout_period: 2419200s
  consumer_id: "0"
  consumer_redistribution_fraction: "0.75"
  distribution_transmission_channel: channel-1
  enabled: true
  historical_entries: "10000"
  provider_fee_pool_addr_str: cosmos1ap0mh6xzfn8943urr84q6ae7zfnar48am2erhd
  provider_reward_denoms: []
  retry_delay_period: 3600s
  reward_denoms: []
  soft_opt_out_threshold: "0"
  transfer_timeout_period: 3600s
  unbonding_period: 1209600s

gRPC​

A user can query the consumer module using gRPC endpoints.

Next Fee Distribution​

The QueryNextFeeDistribution endpoint queries next fee distribution data.

interchain_security.ccv.consumer.v1.Query/QueryNextFeeDistribution
Example
grpcurl -plaintext localhost:9090 interchain_security.ccv.consumer.v1.Query/QueryNextFeeDistribution

Output:

{
  "data": {
    "currentHeight": "402",
    "lastHeight": "400",
    "nextHeight": "420",
    "distributionFraction": "0.75"
  }
}

Provider Info​

The QueryProviderInfo endpoint queries provider info.

interchain_security.ccv.consumer.v1.Query/QueryProviderInfo
Example
grpcurl -plaintext localhost:9090 interchain_security.ccv.consumer.v1.Query/QueryProviderInfo

Output:

{
  "consumer": {
    "chainID": "pion-1",
    "clientID": "07-tendermint-0",
    "connectionID": "connection-0",
    "channelID": "channel-0"
  },
  "provider": {
    "chainID": "provider",
    "clientID": "07-tendermint-0",
    "connectionID": "connection-0",
    "channelID": "channel-0"
  }
}

Throttle State​

The QueryThrottleState endpoint queries on-chain state relevant with slash packet throttling.

interchain_security.ccv.consumer.v1.Query/QueryThrottleState
Example
grpcurl -plaintext localhost:9090 interchain_security.ccv.consumer.v1.Query/QueryThrottleState

Output:

{
  "slashRecord": {
    "waitingOnReply": true,
    "sendTime": "2024-10-02T07:58:24.405645924Z"
  },
  "packetDataQueue": [
    {
      "type": "CONSUMER_PACKET_TYPE_SLASH",
      "slashPacketData": {
        "validator": {
          "address": "mb06cu8SzQJOdYSzrJAK43Q8at8=",
          "power": "500"
        },
        "valsetUpdateId": "48",
        "infraction": "INFRACTION_DOWNTIME"
      }
    }
  ]
}

Params​

The QueryParams endpoint queries consumer module parameters.

interchain_security.ccv.consumer.v1.Query/QueryParams
Example
grpcurl -plaintext localhost:9090 interchain_security.ccv.consumer.v1.Query/QueryParams

Output:

{
  "params": {
    "enabled": true,
    "blocksPerDistributionTransmission": "1000",
    "distributionTransmissionChannel": "channel-1",
    "providerFeePoolAddrStr": "cosmos1ap0mh6xzfn8943urr84q6ae7zfnar48am2erhd",
    "ccvTimeoutPeriod": "2419200s",
    "transferTimeoutPeriod": "3600s",
    "consumerRedistributionFraction": "0.75",
    "historicalEntries": "10000",
    "unbondingPeriod": "1209600s",
    "softOptOutThreshold": "0",
    "retryDelayPeriod": "3600s",
    "consumerId": "0"
  }
}

REST​

A user can query the consumer module using REST endpoints.

Next Fee Distribution​

The next-fee-distribution endpoint queries next fee distribution data.

/interchain_security/ccv/consumer/next-fee-distribution
Example
curl http://localhost:1317/interchain_security/ccv/consumer/next-fee-distribution

Output:

{
  "data": {
    "currentHeight": "402",
    "lastHeight": "400",
    "nextHeight": "420",
    "distributionFraction": "0.75"
  }
}

Provider Info​

The QueryProviderInfo endpoint queries provider info.

/interchain_security/ccv/consumer/provider-info
Example
curl http://localhost:1317/interchain_security/ccv/consumer/provider-info

Output:

{
  "consumer": {
    "chainID": "pion-1",
    "clientID": "07-tendermint-0",
    "connectionID": "connection-0",
    "channelID": "channel-0"
  },
  "provider": {
    "chainID": "provider",
    "clientID": "07-tendermint-0",
    "connectionID": "connection-0",
    "channelID": "channel-0"
  }
}

Throttle State​

The throttle_state endpoint queries on-chain state relevant with slash packet throttling.

/interchain_security/ccv/consumer/throttle_state
Example
curl http://localhost:1317/interchain_security/ccv/consumer/throttle_state

Output:

{
  "consumer": {
    "chainID": "pion-1",
    "clientID": "07-tendermint-0",
    "connectionID": "connection-0",
    "channelID": "channel-0"
  },
  "provider": {
    "chainID": "provider",
    "clientID": "07-tendermint-0",
    "connectionID": "connection-0",
    "channelID": "channel-0"
  }
}

Params​

The params endpoint queries consumer module parameters.

/interchain_security/ccv/consumer/params
Example
curl http://localhost:1317/interchain_security/ccv/consumer/params

Output:

{
  "params": {
    "enabled": true,
    "blocksPerDistributionTransmission": "1000",
    "distributionTransmissionChannel": "channel-1",
    "providerFeePoolAddrStr": "cosmos1ap0mh6xzfn8943urr84q6ae7zfnar48am2erhd",
    "ccvTimeoutPeriod": "2419200s",
    "transferTimeoutPeriod": "3600s",
    "consumerRedistributionFraction": "0.75",
    "historicalEntries": "10000",
    "unbondingPeriod": "1209600s",
    "softOptOutThreshold": "0",
    "retryDelayPeriod": "3600s",
    "consumerId": "0"
  }
}