Call Header

Typed Struct (EIP712)

Call(uint16 call_index,uint16 payer_index,string call_type,address from,address to,string to_ens,uint256 value,uint32 gas_limit,uint16 permissions,uint16 validation,string flow_control,bool returned_false_means_fail,uint16 jump_on_success,uint16 jump_on_fail,uint32 variable_arguments_start,uint32 variable_arguments_end,string method_interface)

Params

Name	Type
call_index	uint16
payer_index	uint16
call_type	string
from	address
to	address
to_ens	string
value	uint256
gas_limit	uint32
permissions	uint16
validation	uint16
flow_control	string
returned_false_means_fail	bool
jump_on_success	uint16
jump_on_fail	uint16
variable_arguments_start	uint32
variable_arguments_end	uint32
method_interface	string

call_index

Call index is the call position, stating from 1. The value must be equal to position of the call in the list of calls inside the FCT.

Call index param helps the user to identify the call from which a returned data s used when signing an EIP-712 FCT message

payer_index

The index of the "from" address that will pay for the call, starting from 1. Usually it will be the same value as the call_index. If the payer is 0, the payment of the call will be equally divided by the other payers of the FCT.

If all payer indexes on an FCT are 0, the activator will pay for this FCT

call_type

FCT supports three types of calls: call, staticcall and delegatecall

flow_control is defined using human readable string, so the user can easily see the call type.

EIP712 String	Value	Meaning
"action"	0	Executing the call using the low level "call" function. The contract being called can change blockchain state and sees the FCT_Runner as the calling entity.
"view only"	1	Executing the call using the low level "staticcall" function. The contract being called is not allowed to change the blockchain state and sees the FCT_Runner as the calling entity.
"library"	2	Executing the call using the low level "delegatecall" function. The contract being called runs in the context of the FCT_Runner, has access the FCT_Runner storage variables and any calls from it to an external contracts will be looked as being called directly from the FCT_Runner address.

"library" is extremely powerful, yet dangerous. It is recommended to use only trusted contracts for "library" calls and protect the calling address by forcing to use both "to" address and "to_ens" (Preferred LocalENS of type: library)

from

From is the contract that executes the call, usually an on-chain-wallet like the vault. This contract must implement the IFCT_Runner interface.

to

Destination of the call. A smart contract address in case of calling a contract, or any address in case of sending ETH.

to_ens (optional)

ENS is also supported.

value

The native token value that will be sent with the call.

gas_limit

There is possibly to limit the gas usage per call. When set to 0, no limit is enforced.

permissions

permissions are 16 bits that can be used to define security groups for FCTs

The permissions are just passed transparently, by the FCT_Engine, to the FCT Runner. The FCT Runner can implement any logic regarding the permissions bits enabling an extendable execution model for FCTs.

For example, FCT Runner can allow a specific address (child account) to run only FCTs that has 0x0001 permission, while limiting execution of FCTs with 0x0001 permissions in terms of protocols, amounts and rate.

validation

Validation is used in order to run a validation at the end of the call, by setting the entry point index.

Set to 0, in order to disable validation for this call.

flow_control

FCT supports if/then functionality via the flow_control field combined with the "jump on" fields.

flow_control is defined using human readable string, so the user can easily see the flow condition.

EIP712 String	Value	Meaning
"continue on success, revert on fail"	0	If call reverts, revert the whole FCT, otherwise, continue to the next call according to the jump_on_success field
"continue on success, stop on fail"	1	If call reverts, stop FCT execution (previous calls are not reverted), otherwise, continue to the next call according to the jump_on_success field
"continue on success, continue on fail"	2	Whether call reverts or not, continue to the next call according to the jump_on_success and jump_on_fail fields respectively
"revert on success, continue on fail"	3	If call reverts, continue to the next call according to the jump_on_fail field, otherwise, revert the whole FCT
"revert on success, stop on fail"	4	If call reverts, stop FCT execution (previous calls are not reverted), otherwise, revert the whole FCT
"stop on success, continue on fail"	5	If call reverts, continue to the next call according to the jump_on_fail field, otherwise, stop FCT execution (previous calls are not reverted)
"stop on success, revert on fail"	6	If call reverts, revert the whole FCT, otherwise, stop FCT execution (previous calls are not reverted)
"stop on success, stop on fail"	7	Whether call reverts or not, stop FCT execution (previous calls are not reverted)

if/then blocks can be achieved by using one of the "cont" flow controls and setting the "jump_on" values

jump_on_success

Part of the flow control. Specify the amount of calls to jump over when current call succeed. When setting to 0 and the current call succeed, the adjacent call will be executed.

This value is ignored when "stop on success" or "revert on success" is being used

jump_on_fail

Part of the flow control. Specify the amount of calls to jump over when current call fails. When setting to 0 and the current call fails, the adjacent call will be executed.

This value is ignored when "stop on fail" or "revert on fail" is being used

variable_arguments_start

Specify the staring point, in bytes, for the FCT engine's variables searcher.

Both variable_arguments start and end, gives a hint to the FCT engine where, in method's call data, variable values might be used.

Set both to 0, if no variables are being used in method's call data, in order to save gas.

variable_arguments_end

Specify the ending point (not including), in bytes, for the FCT engine's variables searcher.

When using a solver call, both values should be 0

method_interface

The name of the function to be called followed by type-names, in parentheses, without any spaces. This is used in order to calculate the function signature and selector. See more info here

ERC20 transfer method interface looks like this: "transfer(address,uint256)"