openzeppelin-contracts/docs/modules/api/pages/metatx.adoc

:github-icon: pass:[<svg class="icon"><use href="#github-icon"/></svg>]
:xref-ERC2771Context-constructor-address-: xref:metatx.adoc#ERC2771Context-constructor-address-
:xref-ERC2771Context-isTrustedForwarder-address-: xref:metatx.adoc#ERC2771Context-isTrustedForwarder-address-
:xref-ERC2771Context-_msgSender--: xref:metatx.adoc#ERC2771Context-_msgSender--
:xref-ERC2771Context-_msgData--: xref:metatx.adoc#ERC2771Context-_msgData--
:xref-ERC2771Context-_contextSuffixLength--: xref:metatx.adoc#ERC2771Context-_contextSuffixLength--
:ERC2771Context: pass:normal[xref:metatx.adoc#ERC2771Context[`ERC2771Context`]]
:xref-MinimalForwarder-constructor--: xref:metatx.adoc#MinimalForwarder-constructor--
:xref-MinimalForwarder-getNonce-address-: xref:metatx.adoc#MinimalForwarder-getNonce-address-
:xref-MinimalForwarder-verify-struct-MinimalForwarder-ForwardRequest-bytes-: xref:metatx.adoc#MinimalForwarder-verify-struct-MinimalForwarder-ForwardRequest-bytes-
:xref-MinimalForwarder-execute-struct-MinimalForwarder-ForwardRequest-bytes-: xref:metatx.adoc#MinimalForwarder-execute-struct-MinimalForwarder-ForwardRequest-bytes-
:xref-EIP712-_domainSeparatorV4--: xref:utils.adoc#EIP712-_domainSeparatorV4--
:xref-EIP712-_hashTypedDataV4-bytes32-: xref:utils.adoc#EIP712-_hashTypedDataV4-bytes32-
:xref-EIP712-eip712Domain--: xref:utils.adoc#EIP712-eip712Domain--
:xref-IERC5267-EIP712DomainChanged--: xref:interfaces.adoc#IERC5267-EIP712DomainChanged--
= Meta Transactions

[.readme-notice]
NOTE: This document is better viewed at https://docs.openzeppelin.com/contracts/api/metatx

== Core

:constructor: pass:normal[xref:#ERC2771Context-constructor-address-[`++constructor++`]]
:isTrustedForwarder: pass:normal[xref:#ERC2771Context-isTrustedForwarder-address-[`++isTrustedForwarder++`]]
:_msgSender: pass:normal[xref:#ERC2771Context-_msgSender--[`++_msgSender++`]]
:_msgData: pass:normal[xref:#ERC2771Context-_msgData--[`++_msgData++`]]
:_contextSuffixLength: pass:normal[xref:#ERC2771Context-_contextSuffixLength--[`++_contextSuffixLength++`]]

[.contract]
[[ERC2771Context]]
=== `++ERC2771Context++` link:https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v4.9.5/contracts/metatx/ERC2771Context.sol[{github-icon},role=heading-link]

[.hljs-theme-light.nopadding]
```solidity
import "@openzeppelin/contracts/metatx/ERC2771Context.sol";
```

Context variant with ERC2771 support.

WARNING: The usage of `delegatecall` in this contract is dangerous and may result in context corruption.
Any forwarded request to this contract triggering a `delegatecall` to itself will result in an invalid {_msgSender}
recovery.

[.contract-index]
.Functions
--
* {xref-ERC2771Context-constructor-address-}[`++constructor(trustedForwarder)++`]
* {xref-ERC2771Context-isTrustedForwarder-address-}[`++isTrustedForwarder(forwarder)++`]
* {xref-ERC2771Context-_msgSender--}[`++_msgSender()++`]
* {xref-ERC2771Context-_msgData--}[`++_msgData()++`]
* {xref-ERC2771Context-_contextSuffixLength--}[`++_contextSuffixLength()++`]

--

[.contract-item]
[[ERC2771Context-constructor-address-]]
==== `[.contract-item-name]#++constructor++#++(address trustedForwarder)++` [.item-kind]#internal#

[.contract-item]
[[ERC2771Context-isTrustedForwarder-address-]]
==== `[.contract-item-name]#++isTrustedForwarder++#++(address forwarder) → bool++` [.item-kind]#public#

[.contract-item]
[[ERC2771Context-_msgSender--]]
==== `[.contract-item-name]#++_msgSender++#++() → address++` [.item-kind]#internal#

[.contract-item]
[[ERC2771Context-_msgData--]]
==== `[.contract-item-name]#++_msgData++#++() → bytes++` [.item-kind]#internal#

[.contract-item]
[[ERC2771Context-_contextSuffixLength--]]
==== `[.contract-item-name]#++_contextSuffixLength++#++() → uint256++` [.item-kind]#internal#

ERC-2771 specifies the context as being a single address (20 bytes).

== Utils

:ForwardRequest: pass:normal[xref:#MinimalForwarder-ForwardRequest[`++ForwardRequest++`]]
:constructor: pass:normal[xref:#MinimalForwarder-constructor--[`++constructor++`]]
:getNonce: pass:normal[xref:#MinimalForwarder-getNonce-address-[`++getNonce++`]]
:verify: pass:normal[xref:#MinimalForwarder-verify-struct-MinimalForwarder-ForwardRequest-bytes-[`++verify++`]]
:execute: pass:normal[xref:#MinimalForwarder-execute-struct-MinimalForwarder-ForwardRequest-bytes-[`++execute++`]]

[.contract]
[[MinimalForwarder]]
=== `++MinimalForwarder++` link:https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v4.9.5/contracts/metatx/MinimalForwarder.sol[{github-icon},role=heading-link]

[.hljs-theme-light.nopadding]
```solidity
import "@openzeppelin/contracts/metatx/MinimalForwarder.sol";
```

Simple minimal forwarder to be used together with an ERC2771 compatible contract. See {ERC2771Context}.

MinimalForwarder is mainly meant for testing, as it is missing features to be a good production-ready forwarder. This
contract does not intend to have all the properties that are needed for a sound forwarding system. A fully
functioning forwarding system with good properties requires more complexity. We suggest you look at other projects
such as the GSN which do have the goal of building a system like that.

[.contract-index]
.Functions
--
* {xref-MinimalForwarder-constructor--}[`++constructor()++`]
* {xref-MinimalForwarder-getNonce-address-}[`++getNonce(from)++`]
* {xref-MinimalForwarder-verify-struct-MinimalForwarder-ForwardRequest-bytes-}[`++verify(req, signature)++`]
* {xref-MinimalForwarder-execute-struct-MinimalForwarder-ForwardRequest-bytes-}[`++execute(req, signature)++`]

[.contract-subindex-inherited]
.EIP712
* {xref-EIP712-_domainSeparatorV4--}[`++_domainSeparatorV4()++`]
* {xref-EIP712-_hashTypedDataV4-bytes32-}[`++_hashTypedDataV4(structHash)++`]
* {xref-EIP712-eip712Domain--}[`++eip712Domain()++`]

[.contract-subindex-inherited]
.IERC5267

--

[.contract-index]
.Events
--

[.contract-subindex-inherited]
.EIP712

[.contract-subindex-inherited]
.IERC5267
* {xref-IERC5267-EIP712DomainChanged--}[`++EIP712DomainChanged()++`]

--

[.contract-item]
[[MinimalForwarder-constructor--]]
==== `[.contract-item-name]#++constructor++#++()++` [.item-kind]#public#

[.contract-item]
[[MinimalForwarder-getNonce-address-]]
==== `[.contract-item-name]#++getNonce++#++(address from) → uint256++` [.item-kind]#public#

[.contract-item]
[[MinimalForwarder-verify-struct-MinimalForwarder-ForwardRequest-bytes-]]
==== `[.contract-item-name]#++verify++#++(struct MinimalForwarder.ForwardRequest req, bytes signature) → bool++` [.item-kind]#public#

[.contract-item]
[[MinimalForwarder-execute-struct-MinimalForwarder-ForwardRequest-bytes-]]
==== `[.contract-item-name]#++execute++#++(struct MinimalForwarder.ForwardRequest req, bytes signature) → bool, bytes++` [.item-kind]#public#