Messaging functions and events

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L1 function reference

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cancelL1ToL2Message

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Description

Cancels an L1 to L2 message. Call this function after calling the startL1ToL2MessageCancellation function. The time between the calls to these two functions must be at least the number of seconds defined by the messageCancellationDelay function. Only a sender can cancel a message. If the message is missing, the call reverts. Be aware that the message fee is not refunded.

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State Mutability

None.

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Parameters

uint256 toAddress	The address of the L2 contract.
uint256 selector	The function, in the recipient L2 contract, that the message called.
uint256[] calldata payload	The payload of the message.
uint256 nonce	The nonce of the message.

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Returns

bytes32 msgHash	The hash of the canceled message.

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Emitted event

MessageToL2Canceled

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Function definition

Contract: StarknetMessaging.sol

• Function: cancelL1ToL2Message

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consumeMessageFromL2

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Description

Consumes a message that was sent from an L2 contract. Returns the hash of the message.

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State Mutability

None.

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Parameters

uint256 fromAddress	The address of the L2 contract sending the message.
uint256[] calldata payload	The payload of the message.

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Returns

bytes32 msgHash	The hash of the consumed message.

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Emitted event

ConsumedMessageToL1

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Function definition

Contract: StarknetMessaging.sol

• Function: consumeMessageFromL2

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getMaxL1MsgFee

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Description

Returns the maximum fee, in Wei, that Starknet accepts for a single message. If the fee passed is higher than this value, the transaction is not accepted.

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State Mutability

pure

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Parameters

None.

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Returns

uint256 MAX_L1_MSG_FEE	The maximum fee, in Wei, that Starknet accepts for a single message.

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Function definition

Contract: StarknetMessaging.sol

• Function: getMaxL1MsgFee

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l1ToL2MessageCancellations

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Description

Returns the timestamp of the cancellation request.

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State Mutability

view

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Parameters

bytes32 msgHash	The message hash.

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Returns

uint256 result	The Ethereum block timestamp.

Returns 0 if cancelL1ToL2Message was not called with the message hash msgHash.

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Function definition

Contract: StarknetMessaging.sol

• Function: l1ToL2MessageCancellations

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l1ToL2MessageNonce

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Description

Returns the nonce of the next message sent to the L2 contract. So if If n messages have been sent to Starknet, this function returns n + 1.

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State Mutability

view

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Parameters

None.

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Returns

uint256 nonce	The nonce of the next message sending to L2 contract.

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Function definition

Contract: StarknetMessaging.sol

• Function: l1ToL2MessageNonce

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l1ToL2Messages

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Description

Indicates if a pending message is associated with a given message hash.

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State Mutability

view

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Parameters

bytes32 msgHash	The message hash.

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Returns

Returns uint256 result, where result is one of the following:

message_fee + 1	A pending message is associated with the msgHash parameter.
0	No pending message is associated with the msgHash parameter.

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Function definition

Contract: StarknetMessaging.sol

• Function: l1ToL2Messages

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l2ToL1Messages

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Description

Indicates the number of pending messages associated with a given message hash.

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State Mutability

view

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Parameters

bytes32 msgHash	The message hash.

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Returns

Returns uint256 result, where result is the number of pending messages associated with the msgHash parameter.

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Function definition

Contract: StarknetMessaging.sol

• Function: l2ToL1Messages

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messageCancellationDelay

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Description

Returns the time interval, in seconds, after which you can cancel a message starting from the moment of calling the startL1ToL2MessageCancellation function. You can get the real value by calling the messageCancellationDelay function on a block explorer, such as Etherscan.

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State Mutability

view

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Parameters

None.

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Returns

uint256 result	The time interval.

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Function definition

Contract: StarknetMessaging.sol

• Function: messageCancellationDelay

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sendMessageToL2

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Description

Sends a message to an L2 contract. The message fee is the cost of executing this function.

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State Mutability

payable

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Parameters

uint256 toAddress	The address of the L2 contract.
uint256 selector	The function, in the recipient L2 contract, that the message called.
uint256[] calldata payload	The payload of the message.

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Returns

bytes32 msgHash	The hash of the message.
uint256 nonce	The nonce of the message.

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Emitted event

LogMessageToL2

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Function definition

Contract: StarknetMessaging.sol

• Function: sendMessageToL2

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startL1ToL2MessageCancellation

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Description

Starts the cancellation of a message from L1 to L2. You can cancel a message after a predefined about of time from the moment this function is called. The amount of time is set by the messageCancellationDelay function. You can only call this function for a message that is currently pending, and the caller must be the sender of that message.

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State Mutability

None.

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Parameters

uint256 toAddress	The address of the L2 contract.
uint256 selector	The function, in the recipient L2 contract, that the message called.
uint256[] calldata payload	The payload of the message.
uint256 nonce	The nonce of the message.

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Returns

bytes32 msgHash	The hash of the cancellation message.

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Emitted event

MessageToL2CancellationStarted

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Function definition

Contract: StarknetMessaging.sol

• Function: startL1ToL2MessageCancellation

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L1 event reference

Events are listed in alphabetical order.

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ConsumedMessageToL1

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Description

This event is emitted when a message from L2 to L1 is consumed by the consumeMessageFromL2 function.

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Event attributes

uint256 indexed fromAddress	The address of the sender on L2.
address indexed toAddress	The address of the receiver on L1.
uint256[] payload	The payload of the consumed message.

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Event definition

• Contract: IStarknetMessagingEvents
• Event: ConsumedMessageToL1

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LogMessageToL2

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Description

This event is emitted when a message is sent from L1 to L2 by the sendMessageToL2 function.

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Event attributes

address indexed fromAddress	The address of the sender on L1.
uint256 indexed toAddress	The address of the receiver on L2.
uint256 indexed selector	The function, in the recipient L2 contract, that the message called.
uint256[] payload	The payload of the message.
uint256 nonce	The nonce of the message.
uint256 fee	The fee associated with the message.

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Event definition

• Contract: IStarknetMessagingEvents
• Event: LogMessageToL2

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MessageToL2Canceled

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Description

This event is emitted when an L1 to L2 message is canceled by the cancelL1ToL2Message function.

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Event attributes

address indexed fromAddress	The address of the sender on L1.
uint256 indexed toAddress	The address of the receiver on L2.
uint256 indexed selector	The function, in the recipient L2 contract, that the message called.
uint256[] payload	The payload of the canceled message.
uint256 nonce	The nonce of the canceled message.

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Event definition

• Contract: IStarknetMessagingEvents
• Event: MessageToL2Canceled

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MessageToL2CancellationStarted

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Description

This event is emitted when the cancellation of an L1 to L2 message is started by the startL1ToL2MessageCancellation function.

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Event attributes

address indexed fromAddress	The address of the sender on L1.
uint256 indexed toAddress	The address of the receiver on L2.
uint256 indexed selector	The function, in the recipient L2 contract, that the message called.
uint256[] payload	The payload of the message to be canceled.
uint256 nonce	The nonce of the message to be canceled.

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Event definition

• Contract: IStarknetMessagingEvents
• Event: MessageToL2CancellationStarted