Adds "real" L1 and L2 message passing contracts.

packages/contracts/contracts/optimistic-ethereum/bridge/BaseCrossDomainMessenger.sol

@@ -0,0 +1,67 @@
+pragma solidity ^0.5.0;
+
+/**
+ * @title L1CrossDomainMessenger
+ */
+contract BaseCrossDomainMessenger {
+    /*
+     * Contract Variables
+     */
+
+    mapping (bytes32 => bool) public receivedMessages;
+    mapping (bytes32 => bool) public sentMessages;
+    address public targetMessengerAddress;
+    uint256 public messageNonce;
+    address public xDomainMessageSender;
+
+
+    /*
+     * Public Functions
+     */
+
+    /**
+     * Sets the target messenger address.
+     * @param _targetMessengerAddress New messenger address.
+     */
+    function setTargetMessengerAddress(
+        address _targetMessengerAddress
+    )
+        public
+    {
+        targetMessengerAddress = _targetMessengerAddress;
+    }
+
+
+    /*
+     * Internal Functions
+     */
+
+    /**
+     * Generates the correct cross domain calldata for a message.
+     * @param _target Target contract address.
+     * @param _sender Message sender address.
+     * @param _message Message to send to the target.
+     * @param _messageNonce Nonce for the provided message.
+     * @return ABI encoded cross domain calldata.
+     */
+    function _getXDomainCalldata(
+        address _target,
+        address _sender,
+        bytes memory _message,
+        uint256 _messageNonce
+    )
+        internal
+        pure
+        returns (
+            bytes memory
+        )
+    {
+        return abi.encodeWithSelector(
+            bytes4(keccak256(bytes("relayMessage(address,address,bytes,uint256)"))),
+            _target,
+            _sender,
+            _message,
+            _messageNonce
+        );
+    }
+}

packages/contracts/contracts/optimistic-ethereum/bridge/L1CrossDomainMessenger.interface.sol

@@ -0,0 +1,81 @@
+pragma solidity ^0.5.0;
+pragma experimental ABIEncoderV2;
+
+/* Library Imports */
+import { DataTypes } from "../utils/libraries/DataTypes.sol";
+
+/**
+ * @title IL1CrossDomainMessenger
+ */
+contract IL1CrossDomainMessenger {
+    /*
+     * Contract Variables
+     */
+
+    mapping (bytes32 => bool) public receivedMessages;
+    mapping (bytes32 => bool) public sentMessages;
+    address public targetMessengerAddress;
+    uint256 public messageNonce;
+    address public xDomainMessageSender;
+
+    /*
+     * Data Structures
+     */
+
+    struct L2MessageInclusionProof {
+        bytes32 stateRoot;
+        uint256 stateRootIndex;
+        DataTypes.StateElementInclusionProof stateRootProof;
+        bytes stateTrieWitness;
+        bytes storageTrieWitness;
+    }
+
+
+    /*
+     * Public Functions
+     */
+
+    /**
+     * Relays a cross domain message to a contract.
+     * @param _target Target contract address.
+     * @param _sender Message sender address.
+     * @param _message Message to send to the target.
+     * @param _messageNonce Nonce for the provided message.
+     * @param _proof Inclusion proof for the given message.
+     */
+    function relayMessage(
+        address _target,
+        address _sender,
+        bytes memory _message,
+        uint256 _messageNonce,
+        L2MessageInclusionProof memory _proof
+    ) public;
+
+    /**
+     * Sends a cross domain message to the target messenger.
+     * @param _target Target contract address.
+     * @param _message Message to send to the target.
+     * @param _gasLimit Gas limit for the provided message.
+     */
+    function sendMessage(
+        address _target,
+        bytes memory _message,
+        uint32 _gasLimit
+    ) public;
+
+    /**
+     * Replays a cross domain message to the target messenger.
+     * @param _target Target contract address.
+     * @param _sender Original sender address.
+     * @param _message Message to send to the target.
+     * @param _messageNonce Nonce for the provided message.
+     * @param _gasLimit Gas limit for the provided message.
+     */
+    function replayMessage(
+        address _target,
+        address _sender,
+        bytes memory _message,
+        uint256 _messageNonce,
+        uint32 _gasLimit
+    ) public;
+}