Gas Optimizations

[code423n4]

Gas report

[G-01] Avoid using SafeMath on solidity v8 and newer

The SafeMath library validates if an arithmetic operation would result in an integer overflow/underflow. If it would, the library throws an exception, effectively reverting the transaction.

Since Solidity 0.8, the overflow/underflow check is implemented on the language level - it adds the validation to the bytecode during compilation.

You don't need the SafeMath library for Solidity 0.8+

[G-02] On contract DNSSEC.sol the variable anchors should be immutable

[G-03] On BaseRegistrarImplementation ENS and basenode should be immutable

[G-04] Use unchecked in ethregistrar/StringUtils.sol

In the strlen function use unchecked to save gas:

    function strlen(string memory s) internal pure returns (uint) {
        uint len;
        uint i = 0;
        uint bytelength = bytes(s).length;
+       unchecked{
        for(len = 0; i < bytelength; len++) {
            bytes1 b = bytes(s)[i];
            if(b < 0x80) {
                i += 1;
            } else if (b < 0xE0) {
                i += 2;
            } else if (b < 0xF0) {
                i += 3;
            } else if (b < 0xF8) {
                i += 4;
            } else if (b < 0xFC) {
                i += 5;
            } else {
                i += 6;
            }
        }
+       }
        return len;
    }

[G-05] Take in mind you shoul only use unchecked when its safe to increment without overflow, like in loops iterator.

Use this pattern;

for (uint256 i; i < length;) {
    // code here
    unchecked { ++i; }
}

On

ontracts/dnssec-oracle/BytesUtils.sol:266:        for(uint i = 0; i < len; i++) {
contracts/dnssec-oracle/BytesUtils.sol:313:        for(uint256 idx = off; idx < off + len; idx++) {
contracts/dnssec-oracle/DNSSECImpl.sol:93:        for(uint i = 0; i < input.length; i++) {
contracts/dnssec-oracle/algorithms/EllipticCurve.sol:304:        for(uint i = 0; i < exp; i++) {
contracts/ethregistrar/BulkRenewal.sol:41:        for (uint256 i = 0; i < names.length; i++) {
contracts/ethregistrar/BulkRenewal.sol:56:        for (uint256 i = 0; i < names.length; i++) {
contracts/ethregistrar/ETHRegistrarController.sol:256:        for (uint256 i = 0; i < data.length; i++) {
contracts/ethregistrar/StringUtils.sol:14:        for(len = 0; i < bytelength; len++) {
contracts/resolvers/Multicallable.sol:10:        for(uint i = 0; i < data.length; i++) {
contracts/wrapper/ERC1155Fuse.sol:92:        for (uint256 i = 0; i < accounts.length; ++i) {
contracts/wrapper/ERC1155Fuse.sol:205:        for (uint256 i = 0; i < ids.length; ++i) {

[G-06] Use unchecked in resolvers/profiles/DNSResolver.sol

Change

contracts/resolvers/profiles/DNSResolver.sol:108:        versions[node]++;
contracts/resolvers/profiles/DNSResolver.sol:159:                nameEntriesCount[node][version][nameHash]++;

To

contracts/resolvers/profiles/DNSResolver.sol:108:        unchecked { versions[node]++; }
contracts/resolvers/profiles/DNSResolver.sol:159:        unchecked {        nameEntriesCount[node][version][nameHash]++; }

[L-07] The withdraw function should be external

The withdraw function of ETHRegistrarController.sol should be external

[G-08] There are two contracts with the same funcionality

Avoid using Owned onstead of that use the Ownable contract from openzepellin as you do with other contracts