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Merge pull request #7 from ensdomains/feat/bet-552-aliasing
- added placeholder OwnedResolver.sol - added setAlias(fromName, toName) - added getAlias(fromName): toName | undefined - added tests
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‎contracts/src/resolver/OwnedResolver.sol‎

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// SPDX-License-Identifier: MIT
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pragma solidity ^0.8.24;
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import {NameCoder} from "@ens/contracts/utils/NameCoder.sol";
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import {OwnedResolverLib} from "./libraries/OwnedResolverLib.sol";
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/// @notice An owned resolver that supports multiple names and internal aliasing.
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///
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/// * Resolved names find the longest match.
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/// * Successful matches recursively check for additional aliasing.
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/// * Cycles of length 1 apply once.
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/// * Cycles of length 2+ result in OOG.
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///
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/// `setAlias("a.eth", "b.eth")`
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/// eg. `getAlias("a.eth") => "b.eth"`
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/// eg. `getAlias("[sub].a.eth") => "[sub].b.eth"`
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/// eg. `getAlias("[x.y].a.eth") => "[x.y].b.eth"`
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/// eg. `getAlias("abc.eth") => ""`
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///
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contract OwnedResolver {
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////////////////////////////////////////////////////////////////////////
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// Events
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////////////////////////////////////////////////////////////////////////
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event AliasChanged(bytes indexed fromName, bytes indexed toName);
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////////////////////////////////////////////////////////////////////////
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// Implementation
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////////////////////////////////////////////////////////////////////////
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/// @notice Create an alias from `fromName` to `toName`.
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///
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/// @param fromName The source DNS-encoded name.
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/// @param toName The destination DNS-encoded name.
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function setAlias(bytes calldata fromName, bytes calldata toName) external {
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_storage().aliases[NameCoder.namehash(fromName, 0)] = toName;
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emit AliasChanged(fromName, toName);
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}
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/// @notice Determine which name is queried when `fromName` is resolved.
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///
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/// @param fromName The source DNS-encoded name.
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///
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/// @return toName The destination DNS-encoded name or empty if not aliased.
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function getAlias(bytes memory fromName) public view returns (bytes memory toName) {
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bytes32 prev;
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for (;;) {
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bytes memory matchName;
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(matchName, fromName) = _resolveAlias(fromName);
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if (fromName.length == 0) break; // no alias
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bytes32 next = keccak256(matchName);
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if (next == prev) break; // same alias
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toName = fromName;
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prev = next;
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}
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}
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////////////////////////////////////////////////////////////////////////
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// Internal Functions
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////////////////////////////////////////////////////////////////////////
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/// @dev Apply one round of longest match aliasing.
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///
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/// @param fromName The source DNS-encoded name.
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///
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/// @return matchName The alias that matched.
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/// @return toName The destination DNS-encoded name or empty if no match.
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function _resolveAlias(
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bytes memory fromName
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) internal view returns (bytes memory matchName, bytes memory toName) {
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mapping(bytes32 => bytes) storage A = _storage().aliases;
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uint256 offset;
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while (offset < fromName.length) {
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matchName = A[NameCoder.namehash(fromName, offset)];
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if (matchName.length > 0) {
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if (offset > 0) {
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// rewrite prefix: [x.y].{fromName[offset:]} => [x.y].{matchName}
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toName = new bytes(offset + matchName.length);
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assembly {
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mcopy(add(toName, 32), add(fromName, 32), offset) // copy prefix
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mcopy(add(toName, add(32, offset)), add(matchName, 32), mload(matchName)) // copy suffix
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}
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} else {
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toName = matchName;
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}
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break;
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}
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(, offset) = NameCoder.nextLabel(fromName, offset);
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}
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}
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/// @dev Access global storage pointer.
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function _storage() internal pure returns (OwnedResolverLib.Storage storage S) {
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uint256 slot = OwnedResolverLib.NAMED_SLOT;
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assembly {
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S.slot := slot
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}
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}
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}

‎contracts/src/resolver/libraries/OwnedResolverLib.sol‎

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// SPDX-License-Identifier: MIT
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pragma solidity >=0.8.13;
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/// @notice Storage layout and roles for OwnedResolver.
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library OwnedResolverLib {
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struct Storage {
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mapping(bytes32 node => bytes) aliases;
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}
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uint256 internal constant NAMED_SLOT = uint256(keccak256("eth.ens.storage.OwnedResolver"));
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}

‎contracts/test/unit/resolver/OwnedResolver.t.sol‎

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// SPDX-License-Identifier: MIT
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pragma solidity ^0.8.13;
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import {Test} from "forge-std/Test.sol";
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import {NameCoder} from "@ens/contracts/utils/NameCoder.sol";
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import {OwnedResolver} from "~src/resolver/OwnedResolver.sol";
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contract OwnedResolverTest is Test {
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OwnedResolver resolver;
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function setUp() external {
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resolver = new OwnedResolver();
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}
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function test_alias_noMatch() external view {
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assertEq(resolver.getAlias(NameCoder.encode("test.eth")), "", "test");
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assertEq(resolver.getAlias(NameCoder.encode("")), "", "root");
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assertEq(resolver.getAlias(NameCoder.encode("xyz")), "", "xyz");
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}
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function test_alias_root() external {
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resolver.setAlias(NameCoder.encode(""), NameCoder.encode("test.eth"));
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assertEq(resolver.getAlias(NameCoder.encode("")), NameCoder.encode("test.eth"), "root");
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assertEq(
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resolver.getAlias(NameCoder.encode("sub")),
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NameCoder.encode("sub.test.eth"),
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"sub"
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);
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}
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function test_alias_exact() external {
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resolver.setAlias(NameCoder.encode("other.eth"), NameCoder.encode("test.eth"));
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assertEq(
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resolver.getAlias(NameCoder.encode("other.eth")),
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NameCoder.encode("test.eth"),
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"exact"
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);
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}
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function test_alias_subdomain() external {
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resolver.setAlias(NameCoder.encode("com"), NameCoder.encode("eth"));
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assertEq(resolver.getAlias(NameCoder.encode("com")), NameCoder.encode("eth"), "exact");
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assertEq(
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resolver.getAlias(NameCoder.encode("test.com")),
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NameCoder.encode("test.eth"),
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"alias"
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);
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}
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function test_alias_recursive() external {
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resolver.setAlias(NameCoder.encode("ens.xyz"), NameCoder.encode("com"));
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resolver.setAlias(NameCoder.encode("com"), NameCoder.encode("eth"));
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assertEq(
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resolver.getAlias(NameCoder.encode("test.ens.xyz")),
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NameCoder.encode("test.eth"),
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"alias"
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);
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}
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}

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