Standardization of bytes29 libraries

packages/contracts/contracts/AttestationCollector.sol

@@ -30,12 +30,12 @@ contract AttestationCollector is GlobalNotaryRegistry, OwnableUpgradeable {
      * but different root (meaning one of the attestations is fraudulent),
      * we need a system so store all such attestations.
      *
-     * `attestationRoots` stores a list of attested roots for every (domain, nonce) pair
+     * `attestedRoots` stores a list of attested roots for every (domain, nonce) pair
      * `signatures` stores a signature for every submitted (domain, nonce, root) attestation.
      * We only store the first submitted signature for such attestation.
      */
     // [origin => [nonce => [roots]]]
-    mapping(uint32 => mapping(uint32 => bytes32[])) internal attestationRoots;
+    mapping(uint32 => mapping(uint32 => bytes32[])) internal attestedRoots;
     // [origin => [nonce => [root => signature]]]
     mapping(uint32 => mapping(uint32 => mapping(bytes32 => bytes))) internal signatures;
 
@@ -139,8 +139,8 @@ contract AttestationCollector is GlobalNotaryRegistry, OwnableUpgradeable {
         uint32 _nonce,
         uint256 _index
     ) public view returns (bytes32) {
-        require(_index < attestationRoots[_domain][_nonce].length, "!index");
-        return attestationRoots[_domain][_nonce][_index];
+        require(_index < attestedRoots[_domain][_nonce].length, "!index");
+        return attestedRoots[_domain][_nonce][_index];
     }
 
     /**
@@ -149,7 +149,7 @@ contract AttestationCollector is GlobalNotaryRegistry, OwnableUpgradeable {
      * If amount > 1, fraud was committed.
      */
     function rootsAmount(uint32 _domain, uint32 _nonce) external view returns (uint256) {
-        return attestationRoots[_domain][_nonce].length;
+        return attestedRoots[_domain][_nonce].length;
     }
 
     /*╔══════════════════════════════════════════════════════════════════════╗*\
@@ -207,17 +207,17 @@ contract AttestationCollector is GlobalNotaryRegistry, OwnableUpgradeable {
     }
 
     function _storeAttestation(address _notary, bytes29 _view) internal returns (bool) {
-        uint32 domain = _view.attestationDomain();
-        uint32 nonce = _view.attestationNonce();
-        bytes32 root = _view.attestationRoot();
+        uint32 domain = _view.attestedDomain();
+        uint32 nonce = _view.attestedNonce();
+        bytes32 root = _view.attestedRoot();
         require(nonce > latestNonce[domain][_notary], "Outdated attestation");
         // Don't store Attestation, if another Notary
         // have submitted the same (domain, nonce, root) before.
         if (_signatureExists(domain, nonce, root)) return false;
         latestNonce[domain][_notary] = nonce;
         latestRoot[domain][_notary] = root;
-        signatures[domain][nonce][root] = _view.attestationSignature().clone();
-        attestationRoots[domain][nonce].push(root);
+        signatures[domain][nonce][root] = _view.notarySignature().clone();
+        attestedRoots[domain][nonce].push(root);
         return true;
     }
 }

packages/contracts/contracts/Destination.sol

@@ -12,7 +12,7 @@ import { Message } from "./libs/Message.sol";
 import { Header } from "./libs/Header.sol";
 import { Tips } from "./libs/Tips.sol";
 import { TypeCasts } from "./libs/TypeCasts.sol";
-import { SystemMessage } from "./system/SystemMessage.sol";
+import { SystemMessage } from "./libs/SystemMessage.sol";
 import { SystemContract } from "./system/SystemContract.sol";
 import { IMessageRecipient } from "./interfaces/IMessageRecipient.sol";
 // ============ External Imports ============
@@ -146,21 +146,16 @@ contract Destination is Version0, SystemContract, GlobalNotaryRegistry, GuardReg
      */
     function submitAttestation(bytes memory _attestation) external {
         (, bytes29 _view) = _checkNotaryAuth(_attestation);
-        uint32 remoteDomain = _view.attestationDomain();
+        uint32 remoteDomain = _view.attestedDomain();
         require(remoteDomain != localDomain, "Attestation refers to local chain");
-        uint32 nonce = _view.attestationNonce();
+        uint32 nonce = _view.attestedNonce();
         MirrorLib.Mirror storage mirror = allMirrors[activeMirrors[remoteDomain]];
         require(nonce > mirror.nonce, "Attestation older than current state");
-        bytes32 newRoot = _view.attestationRoot();
+        bytes32 newRoot = _view.attestedRoot();
         mirror.setConfirmAt(newRoot, block.timestamp);
         // update nonce
         mirror.setNonce(nonce);
-        emit AttestationAccepted(
-            remoteDomain,
-            nonce,
-            newRoot,
-            _view.attestationSignature().clone()
-        );
+        emit AttestationAccepted(remoteDomain, nonce, newRoot, _view.notarySignature().clone());
     }
 
     /**
@@ -192,35 +187,35 @@ contract Destination is Version0, SystemContract, GlobalNotaryRegistry, GuardReg
      * @param _message Formatted message
      */
     function execute(bytes memory _message) public {
-        bytes29 _m = _message.messageView();
-        bytes29 _header = _m.header();
-        uint32 _remoteDomain = _header.origin();
-        MirrorLib.Mirror storage mirror = allMirrors[activeMirrors[_remoteDomain]];
+        bytes29 messageView = _message.castToMessage();
+        bytes29 header = messageView.header();
+        uint32 remoteDomain = header.origin();
+        MirrorLib.Mirror storage mirror = allMirrors[activeMirrors[remoteDomain]];
         // ensure message was meant for this domain
-        require(_header.destination() == localDomain, "!destination");
+        require(header.destination() == localDomain, "!destination");
         // ensure message has been proven
-        bytes32 _messageHash = _m.keccak();
-        bytes32 _root = mirror.messageStatus[_messageHash];
-        require(MirrorLib.isPotentialRoot(_root), "!exists || executed");
+        bytes32 messageHash = messageView.keccak();
+        bytes32 root = mirror.messageStatus[messageHash];
+        require(MirrorLib.isPotentialRoot(root), "!exists || executed");
         require(
-            acceptableRoot(_remoteDomain, _header.optimisticSeconds(), _root),
+            acceptableRoot(remoteDomain, header.optimisticSeconds(), root),
             "!optimisticSeconds"
         );
         // check re-entrancy guard
         require(entered == 1, "!reentrant");
         entered = 0;
-        _storeTips(_m.tips());
+        _storeTips(messageView.tips());
         // update message status as executed
-        mirror.setMessageStatus(_messageHash, MirrorLib.MESSAGE_STATUS_EXECUTED);
-        address recipient = _checkForSystemMessage(_header.recipient());
+        mirror.setMessageStatus(messageHash, MirrorLib.MESSAGE_STATUS_EXECUTED);
+        address recipient = _checkForSystemMessage(header.recipient());
         IMessageRecipient(recipient).handle(
-            _remoteDomain,
-            _header.nonce(),
-            _header.sender(),
-            mirror.confirmAt[_root],
-            _m.body().clone()
+            remoteDomain,
+            header.nonce(),
+            header.sender(),
+            mirror.confirmAt[root],
+            messageView.body().clone()
         );
-        emit Executed(_remoteDomain, _messageHash);
+        emit Executed(remoteDomain, messageHash);
         // reset re-entrancy guard
         entered = 1;
     }

packages/contracts/contracts/Origin.sol

@@ -10,7 +10,7 @@ import { MerkleLib } from "./libs/Merkle.sol";
 import { Header } from "./libs/Header.sol";
 import { Message } from "./libs/Message.sol";
 import { Tips } from "./libs/Tips.sol";
-import { SystemMessage } from "./system/SystemMessage.sol";
+import { SystemMessage } from "./libs/SystemMessage.sol";
 import { SystemContract } from "./system/SystemContract.sol";
 import { MerkleTreeManager } from "./Merkle.sol";
 import { INotaryManager } from "./interfaces/INotaryManager.sol";
@@ -208,7 +208,7 @@ contract Origin is
         bytes memory _messageBody
     ) external payable notFailed {
         require(_messageBody.length <= MAX_MESSAGE_BODY_BYTES, "msg too long");
-        require(_tips.tipsView().totalTips() == msg.value, "!tips");
+        require(_tips.castToTips().totalTips() == msg.value, "!tips");
         // get the next nonce for the destination domain, then increment it
         nonce = nonce + 1;
         bytes32 _sender = _checkForSystemMessage(_recipientAddress);
@@ -279,8 +279,8 @@ contract Origin is
     function improperAttestation(bytes memory _attestation) public notFailed returns (bool) {
         // This will revert if signature is not valid
         (address _notary, bytes29 _view) = _checkNotaryAuth(_attestation);
-        uint32 _nonce = _view.attestationNonce();
-        bytes32 _root = _view.attestationRoot();
+        uint32 _nonce = _view.attestedNonce();
+        bytes32 _root = _view.attestedRoot();
         // Check if nonce is valid, if not => attestation is fraud
         if (_nonce < historicalRoots.length) {
             if (_root == historicalRoots[_nonce]) {

packages/contracts/contracts/libs/Attestation.sol

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: MIT
 pragma solidity 0.8.13;
 
+import { SynapseTypes } from "./SynapseTypes.sol";
 import { TypedMemView } from "./TypedMemView.sol";
 
 library Attestation {
@@ -24,8 +25,28 @@ library Attestation {
     uint256 internal constant ATTESTATION_DATA_LENGTH = 40;
     uint256 internal constant OFFSET_SIGNATURE = ATTESTATION_DATA_LENGTH;
 
+    /*╔══════════════════════════════════════════════════════════════════════╗*\
+    ▏*║                              MODIFIERS                               ║*▕
+    \*╚══════════════════════════════════════════════════════════════════════╝*/
+
+    modifier onlyAttestation(bytes29 _view) {
+        _view.assertType(SynapseTypes.ATTESTATION);
+        _;
+    }
+
+    /*╔══════════════════════════════════════════════════════════════════════╗*\
+    ▏*║                              FORMATTERS                              ║*▕
+    \*╚══════════════════════════════════════════════════════════════════════╝*/
+
     /**
-     * @notice Returns formatted Attestation with provided fields
+     * @notice Returns a properly typed bytes29 pointer for an attestation payload.
+     */
+    function castToAttestation(bytes memory _payload) internal pure returns (bytes29) {
+        return _payload.ref(SynapseTypes.ATTESTATION);
+    }
+
+    /**
+     * @notice Returns a formatted Attestation payload with provided fields
      * @param _data         Attestation Data (see above)
      * @param _signature    Notary's signature on `_data`
      * @return Formatted attestation
@@ -39,11 +60,11 @@ library Attestation {
     }
 
     /**
-     * @notice Returns formatted Attestation Data with provided fields
+     * @notice Returns a formatted AttestationData payload with provided fields
      * @param _domain   Domain of Origin's chain
      * @param _root     New merkle root
      * @param _nonce    Nonce of the merkle root
-     * @return Formatted data
+     * @return Formatted attestation data
      **/
     function formatAttestationData(
         uint32 _domain,
@@ -54,45 +75,55 @@ library Attestation {
     }
 
     /**
-     * @notice Checks that message is an Attestation, by checking its length
+     * @notice Checks that a payload is a formatted Attestation payload.
      */
     function isAttestation(bytes29 _view) internal pure returns (bool) {
-        // Should have non-zero length for signature. Signature validity is not checked.
+        // Should have at least 1 bytes for the signature.
+        // Signature length or validity is not checked, ECDSA.sol takes care of it.
         return _view.len() > ATTESTATION_DATA_LENGTH;
     }
 
+    /*╔══════════════════════════════════════════════════════════════════════╗*\
+    ▏*║                         ATTESTATION SLICING                          ║*▕
+    \*╚══════════════════════════════════════════════════════════════════════╝*/
+
     /**
      * @notice Returns domain of chain where the Origin contract is deployed
      */
-    function attestationDomain(bytes29 _view) internal pure returns (uint32) {
+    function attestedDomain(bytes29 _view) internal pure onlyAttestation(_view) returns (uint32) {
         return uint32(_view.indexUint(OFFSET_ORIGIN_DOMAIN, 4));
     }
 
     /**
      * @notice Returns nonce of Origin contract at the time, when `root` was the Merkle root.
      */
-    function attestationNonce(bytes29 _view) internal pure returns (uint32) {
+    function attestedNonce(bytes29 _view) internal pure onlyAttestation(_view) returns (uint32) {
         return uint32(_view.indexUint(OFFSET_NONCE, 4));
     }
 
     /**
      * @notice Returns a historical Merkle root from the Origin contract
      */
-    function attestationRoot(bytes29 _view) internal pure returns (bytes32) {
+    function attestedRoot(bytes29 _view) internal pure onlyAttestation(_view) returns (bytes32) {
         return _view.index(OFFSET_ROOT, 32);
     }
 
     /**
      * @notice Returns Attestation's Data, that is going to be signed by the Notary
      */
-    function attestationData(bytes29 _view) internal pure returns (bytes29) {
-        return _view.slice(OFFSET_ORIGIN_DOMAIN, ATTESTATION_DATA_LENGTH, 0);
+    function attestationData(bytes29 _view) internal pure onlyAttestation(_view) returns (bytes29) {
+        return
+            _view.slice(
+                OFFSET_ORIGIN_DOMAIN,
+                ATTESTATION_DATA_LENGTH,
+                SynapseTypes.ATTESTATION_DATA
+            );
     }
 
     /**
      * @notice Returns Notary's signature on AttestationData
      */
-    function attestationSignature(bytes29 _view) internal pure returns (bytes29) {
-        return _view.slice(OFFSET_SIGNATURE, _view.len() - ATTESTATION_DATA_LENGTH, 0);
+    function notarySignature(bytes29 _view) internal pure onlyAttestation(_view) returns (bytes29) {
+        return _view.sliceFrom(OFFSET_SIGNATURE, SynapseTypes.SIGNATURE);
     }
 }

packages/contracts/contracts/libs/Header.sol

@@ -3,7 +3,7 @@ pragma solidity 0.8.13;
 
 import { TypedMemView } from "./TypedMemView.sol";
 import { TypeCasts } from "./TypeCasts.sol";
-import { Message } from "./Message.sol";
+import { SynapseTypes } from "./SynapseTypes.sol";
 
 /**
  * @notice Library for versioned formatting [the header part]
@@ -26,18 +26,46 @@ library Header {
      * [078 .. 082): optimisticSeconds  uint32   4 bytes
      */
 
+    uint256 internal constant OFFSET_VERSION = 0;
     uint256 internal constant OFFSET_ORIGIN = 2;
     uint256 internal constant OFFSET_SENDER = 6;
     uint256 internal constant OFFSET_NONCE = 38;
     uint256 internal constant OFFSET_DESTINATION = 42;
     uint256 internal constant OFFSET_RECIPIENT = 46;
     uint256 internal constant OFFSET_OPTIMISTIC_SECONDS = 78;
 
+    uint256 internal constant HEADER_LENGTH = 82;
+
+    /*╔══════════════════════════════════════════════════════════════════════╗*\
+    ▏*║                              MODIFIERS                               ║*▕
+    \*╚══════════════════════════════════════════════════════════════════════╝*/
+
     modifier onlyHeader(bytes29 _view) {
-        _view.assertType(Message.HEADER_TYPE);
+        _view.assertType(SynapseTypes.MESSAGE_HEADER);
         _;
     }
 
+    /*╔══════════════════════════════════════════════════════════════════════╗*\
+    ▏*║                              FORMATTERS                              ║*▕
+    \*╚══════════════════════════════════════════════════════════════════════╝*/
+
+    /**
+     * @notice Returns a properly typed bytes29 pointer for a header payload.
+     */
+    function castToHeader(bytes memory _payload) internal pure returns (bytes29) {
+        return _payload.ref(SynapseTypes.MESSAGE_HEADER);
+    }
+
+    /**
+     * @notice Returns a formatted Header payload with provided fields
+     * @param _origin               Domain of origin chain
+     * @param _sender               Address that sent the message
+     * @param _nonce                Message nonce on origin chain
+     * @param _destination          Domain of destination chain
+     * @param _recipient            Address that will receive the message
+     * @param _optimisticSeconds    Optimistic period for message execution
+     * @return Formatted header
+     **/
     function formatHeader(
         uint32 _origin,
         bytes32 _sender,
@@ -58,12 +86,24 @@ library Header {
             );
     }
 
-    function headerView(bytes memory _header) internal pure returns (bytes29) {
-        return _header.ref(Message.HEADER_TYPE);
+    /**
+     * @notice Checks that a payload is a formatted Header.
+     */
+    function isHeader(bytes29 _view) internal pure returns (bool) {
+        uint256 length = _view.len();
+        // Check if version exists in the payload
+        if (length < 2) return false;
+        // Check that header version and its length matches
+        return headerVersion(_view) == HEADER_VERSION && length == HEADER_LENGTH;
     }
 
+    /*╔══════════════════════════════════════════════════════════════════════╗*\
+    ▏*║                            HEADER SLICING                            ║*▕
+    \*╚══════════════════════════════════════════════════════════════════════╝*/
+
+    /// @notice Returns header's version field.
     function headerVersion(bytes29 _header) internal pure onlyHeader(_header) returns (uint16) {
-        return uint16(_header.indexUint(0, 2));
+        return uint16(_header.indexUint(OFFSET_VERSION, 2));
     }
 
     /// @notice Returns header's origin field