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Rewrite ExtendedDNSResolver to support more record types #331

Merged
merged 13 commits into from
May 1, 2024
246 changes: 231 additions & 15 deletions contracts/resolvers/profiles/ExtendedDNSResolver.sol
Original file line number Diff line number Diff line change
Expand Up @@ -2,18 +2,65 @@
pragma solidity ^0.8.4;

import "@openzeppelin/contracts/utils/introspection/IERC165.sol";
import "@openzeppelin/contracts/utils/Strings.sol";
import "../../resolvers/profiles/IExtendedDNSResolver.sol";
import "../../resolvers/profiles/IAddressResolver.sol";
import "../../resolvers/profiles/IAddrResolver.sol";
import "../../resolvers/profiles/ITextResolver.sol";
import "../../utils/HexUtils.sol";
import "../../dnssec-oracle/BytesUtils.sol";

/**
* @dev Resolves names on ENS by interpreting record data stored in a DNS TXT record.
* This resolver implements the IExtendedDNSResolver interface, meaning that when
* a DNS name specifies it as the resolver via a TXT record, this resolver's
* resolve() method is invoked, and is passed any additional information from that
* text record. This resolver implements a simple text parser allowing a variety
* of records to be specified in text, which will then be used to resolve the name
* in ENS.
*
* To use this, set a TXT record on your DNS name in the following format:
* ENS1 <address or name of ExtendedDNSResolver> <record data>
*
* For example:
* ENS1 2.dnsname.ens.eth a[60]=0x1234...
*
* The record data consists of a series of key=value pairs, separated by spaces. Keys
* may have an optional argument in square brackets, and values may be either unquoted
* - in which case they may not contain spaces - or single-quoted. Single quotes in
* a quoted value may be backslash-escaped.
*
* Record types:
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How about contenthash?

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There's no browsers that would prioritize a contenthash in ENS over the A records of the domain right now, and no reasonable prospect that that'll change any time soon.

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true, browsers won't care about any of these records, but some people still want to associate IPFS with DNS names. it would be easy to implement because it doesn't require a parameter, (c=<hash>), and then you have complete resolver support.

ps. I know these records need to be evm-readable, but you have 255 chars to work with and humans involved. how about addr[60]=0x00, text[avatar]='http...', and contenthash=<hash>. maybe support addr=0x00 and a=0x00 as well.

pps. dnsname.ens.eth is a mouthful, dns.resolver would be nice.

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true, browsers won't care about any of these records, but some people still want to associate IPFS with DNS names. it would be easy to implement because it doesn't require a parameter, (c=), and then you have complete resolver support.

If there are any integrations that want to read this field from ENS names, I'll happily add support here.

ps. I know these records need to be evm-readable, but you have 255 chars to work with and humans involved. how about addr[60]=0x00, text[avatar]='http...', and contenthash=. maybe support addr=0x00 and a=0x00 as well.

256 characters is only 5 addresses. We don't have a lot of spare space to work with here.

* - a[<coinType>] - Specifies how an `addr()` request should be resolved for the specified
* `coinType`. Ethereum has `coinType` 60. The value must be 0x-prefixed hexadecimal, and will
* be returned unmodified; this means that non-EVM addresses will need to be translated
* into binary format and then encoded in hex.
* Examples:
* - a[60]=0xFe89cc7aBB2C4183683ab71653C4cdc9B02D44b7
* - a[0]=0x00149010587f8364b964fcaa70687216b53bd2cbd798
* - a[e<chainId>] - Specifies how an `addr()` request should be resolved for the specified
* `chainId`. The value must be 0x-prefixed hexadecimal. When encoding an address for an
* EVM-based cryptocurrency that uses a chainId instead of a coinType, this syntax *must*
* be used in place of the coin type - eg, Optimism is `a[e10]`, not `a[2147483658]`.
* A list of supported cryptocurrencies for both syntaxes can be found here:
* https://github.com/ensdomains/address-encoder/blob/master/docs/supported-cryptocurrencies.md
* Example:
* - a[e10]=0xFe89cc7aBB2C4183683ab71653C4cdc9B02D44b7
* - t[<key>] - Specifies how a `text()` request should be resolved for the specified `key`.
* Examples:
* - t[com.twitter]=nicksdjohnson
* - t[url]='https://ens.domains/'
* - t[note]='I\'m great'
*/
contract ExtendedDNSResolver is IExtendedDNSResolver, IERC165 {
using HexUtils for *;
using BytesUtils for *;
using Strings for *;

uint256 private constant COIN_TYPE_ETH = 60;

error NotImplemented();
error InvalidAddressFormat();
error InvalidAddressFormat(bytes addr);

function supportsInterface(
bytes4 interfaceId
Expand All @@ -27,21 +74,190 @@ contract ExtendedDNSResolver is IExtendedDNSResolver, IERC165 {
bytes calldata context
) external pure override returns (bytes memory) {
bytes4 selector = bytes4(data);
if (
selector == IAddrResolver.addr.selector ||
selector == IAddressResolver.addr.selector
) {
if (selector == IAddressResolver.addr.selector) {
(, uint256 coinType) = abi.decode(data[4:], (bytes32, uint256));
if (coinType != COIN_TYPE_ETH) return abi.encode("");
}
(address record, bool valid) = context.hexToAddress(
2,
context.length
);
if (!valid) revert InvalidAddressFormat();
return abi.encode(record);
if (selector == IAddrResolver.addr.selector) {
return _resolveAddr(context);
} else if (selector == IAddressResolver.addr.selector) {
return _resolveAddress(data, context);
} else if (selector == ITextResolver.text.selector) {
return _resolveText(data, context);
}
revert NotImplemented();
}

function _resolveAddress(
bytes calldata data,
bytes calldata context
) internal pure returns (bytes memory) {
(, uint256 coinType) = abi.decode(data[4:], (bytes32, uint256));
bytes memory value;
// Per https://docs.ens.domains/ensip/11#specification
if (coinType & 0x80000000 != 0) {
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value = _findValue(
context,
bytes.concat(
"a[e",
bytes((coinType & 0x7fffffff).toString()),
"]="
)
);
} else {
value = _findValue(
context,
bytes.concat("a[", bytes(coinType.toString()), "]=")
);
}
if (value.length == 0) {
return value;
}
(bytes memory record, bool valid) = value.hexToBytes(2, value.length);
if (!valid) revert InvalidAddressFormat(value);
return record;
}

function _resolveAddr(
bytes calldata context
) internal pure returns (bytes memory) {
bytes memory value = _findValue(context, "a[60]=");
if (value.length == 0) {
return value;
}
(bytes memory record, bool valid) = value.hexToBytes(2, value.length);
if (!valid) revert InvalidAddressFormat(value);
return record;
}

function _resolveText(
bytes calldata data,
bytes calldata context
) internal pure returns (bytes memory) {
(, string memory key) = abi.decode(data[4:], (bytes32, string));
bytes memory value = _findValue(
context,
bytes.concat("t[", bytes(key), "]=")
);
return value;
}

uint256 constant STATE_START = 0;
uint256 constant STATE_IGNORED_KEY = 1;
uint256 constant STATE_IGNORED_KEY_ARG = 2;
uint256 constant STATE_VALUE = 3;
uint256 constant STATE_QUOTED_VALUE = 4;
uint256 constant STATE_UNQUOTED_VALUE = 5;
uint256 constant STATE_IGNORED_VALUE = 6;
uint256 constant STATE_IGNORED_QUOTED_VALUE = 7;
uint256 constant STATE_IGNORED_UNQUOTED_VALUE = 8;

function _findValue(
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bytes memory data,
bytes memory key
) internal pure returns (bytes memory value) {
uint256 state = STATE_START;
uint256 len = data.length;
for (uint256 i = 0; i < len; ) {
if (state == STATE_START) {
if (data.equals(i, key, 0, key.length)) {
i += key.length;
state = STATE_VALUE;
} else {
state = STATE_IGNORED_KEY;
}
} else if (state == STATE_IGNORED_KEY) {
for (; i < len; i++) {
if (data[i] == "=") {
state = STATE_IGNORED_VALUE;
i += 1;
break;
} else if (data[i] == "[") {
state = STATE_IGNORED_KEY_ARG;
i += 1;
break;
}
}
} else if (state == STATE_IGNORED_KEY_ARG) {
for (; i < len; i++) {
if (data[i] == "]") {
state = STATE_IGNORED_VALUE;
i += 1;
if (data[i] == "=") {
i += 1;
}
break;
}
}
} else if (state == STATE_VALUE) {
if (data[i] == "'") {
state = STATE_QUOTED_VALUE;
i += 1;
} else {
state = STATE_UNQUOTED_VALUE;
}
} else if (state == STATE_QUOTED_VALUE) {
uint256 start = i;
uint256 valueLen = 0;
bool escaped = false;
for (; i < len; i++) {
if (escaped) {
data[start + valueLen] = data[i];
valueLen += 1;
escaped = false;
} else {
if (data[i] == "\\") {
escaped = true;
} else if (data[i] == "'") {
return data.substring(start, valueLen);
} else {
data[start + valueLen] = data[i];
valueLen += 1;
}
}
}
} else if (state == STATE_UNQUOTED_VALUE) {
uint256 start = i;
for (; i < len; i++) {
if (data[i] == " ") {
return data.substring(start, i - start);
}
}
return data.substring(start, len - start);
} else if (state == STATE_IGNORED_VALUE) {
if (data[i] == "'") {
state = STATE_IGNORED_QUOTED_VALUE;
i += 1;
} else {
state = STATE_IGNORED_UNQUOTED_VALUE;
}
} else if (state == STATE_IGNORED_QUOTED_VALUE) {
bool escaped = false;
for (; i < len; i++) {
if (escaped) {
escaped = false;
} else {
if (data[i] == "\\") {
escaped = true;
} else if (data[i] == "'") {
i += 1;
while (data[i] == " ") {
i += 1;
}
state = STATE_START;
break;
}
}
}
} else {
assert(state == STATE_IGNORED_UNQUOTED_VALUE);
for (; i < len; i++) {
if (data[i] == " ") {
while (data[i] == " ") {
i += 1;
}
state = STATE_START;
break;
}
}
}
}
return "";
}
}
24 changes: 21 additions & 3 deletions contracts/utils/HexUtils.sol
Original file line number Diff line number Diff line change
Expand Up @@ -12,11 +12,29 @@ library HexUtils {
bytes memory str,
uint256 idx,
uint256 lastIdx
) internal pure returns (bytes32 r, bool valid) {
) internal pure returns (bytes32, bool) {
require(lastIdx - idx <= 64);
(bytes memory r, bool valid) = hexToBytes(str, idx, lastIdx);
if (!valid) {
return (bytes32(0), false);
}
bytes32 ret;
assembly {
ret := shr(mul(4, sub(64, sub(lastIdx, idx))), mload(add(r, 32)))
}
return (ret, true);
}

function hexToBytes(
bytes memory str,
uint256 idx,
uint256 lastIdx
) internal pure returns (bytes memory r, bool valid) {
uint256 hexLength = lastIdx - idx;
if ((hexLength != 64 && hexLength != 40) || hexLength % 2 == 1) {
if (hexLength % 2 == 1) {
revert("Invalid string length");
}
r = new bytes(hexLength / 2);
valid = true;
assembly {
// check that the index to read to is not past the end of the string
Expand Down Expand Up @@ -58,7 +76,7 @@ library HexUtils {
break
}
let combined := or(shl(4, byte1), byte2)
r := or(shl(8, r), combined)
mstore8(add(add(r, 32), div(sub(i, idx), 2)), combined)
}
}
}
Expand Down
8 changes: 8 additions & 0 deletions contracts/utils/TestHexUtils.sol
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,14 @@ import {HexUtils} from "./HexUtils.sol";
contract TestHexUtils {
using HexUtils for *;

function hexToBytes(
bytes calldata name,
uint256 idx,
uint256 lastInx
) public pure returns (bytes memory, bool) {
return name.hexToBytes(idx, lastInx);
}

function hexStringToBytes32(
bytes calldata name,
uint256 idx,
Expand Down
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