feat: implement nft support for the json rpc api library and js mock …

…server (#80)

Signed-off-by: Mariusz Jasuwienas <[email protected]>

src/forwarder/mirror-node-client.js

@@ -60,6 +60,19 @@ class MirrorNodeClient {
         return this._get(`tokens/${tokenId}?${timestamp}`);
     }
 
+    /**
+     * Fetches information about an NFT by its token ID and serial ID.
+     *
+     * @param {string} tokenId the token ID to fetch.
+     * @param {number} serialId the serial ID of the NFT to fetch.
+     * @param {number} blockNumber
+     * @returns {Promise<Record<string, unknown> | null>} a `Promise` resolving to the token information or null if not found.
+     */
+    async getNftByTokenIdAndNumber(tokenId, serialId, blockNumber) {
+        const timestamp = await this.getBlockQueryParam(blockNumber);
+        return this._get(`tokens/${tokenId}/nft/${serialId}?${timestamp}`);
+    }
+
     /**
      * Get token relationship for an account.
      *
@@ -99,6 +112,20 @@ class MirrorNodeClient {
         );
     }
 
+    /**
+     * Fetches token allowances for a specific account, token, and operator.
+     *
+     * @param {string} accountId The owner's account ID.
+     * @param {string} tokenId The token ID.
+     * @param {string} operatorId The operator's account ID.
+     * @returns {Promise<{ allowances: { approved_for_all: boolean }[] } | null>} A `Promise` resolving to the approval.
+     */
+    getAllowanceForNFT(accountId, tokenId, operatorId) {
+        return this._get(
+            `accounts/${accountId}/allowances/nfts?token.id=${tokenId}&account.id=${operatorId}`
+        );
+    }
+
     /**
      * Fetches account information by account ID, alias, or EVM address.
      *

src/index.d.ts

@@ -32,6 +32,23 @@ interface IMirrorNodeClient {
      */
     getTokenById(tokenId: string, blockNumber: number): Promise<Record<string, unknown> | null>;
 
+    /**
+     * Get NFT by token id and serial id.
+     *
+     * Returns token NFT entity information given the token id and serial id.
+     *
+     * This method should call the Mirror Node API endpoint `GET /api/v1/tokens/{tokenId}/nft/{serialId}`.
+     *
+     * @param tokenId The ID of the token to return information for.
+     * @param serialId The serial id of the NFT.
+     * @param blockNumber
+     */
+    getNftByTokenIdAndNumber(
+        tokenId: string,
+        serialId: number,
+        blockNumber: number
+    ): Promise<Record<string, unknown> | null>;
+
     /**
      * Get token relationship for an account.
      *
@@ -91,6 +108,26 @@ interface IMirrorNodeClient {
         }[];
     } | null>;
 
+    /**
+     * Returns information for non-fungible token allowances for an account.
+     *
+     * NOTE: `blockNumber` is not yet included until we fix issue
+     * https://github.com/hashgraph/hedera-forking/issues/89.
+     *
+     * @param accountId Account alias or account id or evm address.
+     * @param tokenId The ID of the token to return information for.
+     * @param operatorId The ID of the operator to return information for.
+     */
+    getAllowanceForNFT(
+        accountId: string,
+        tokenId: string,
+        operatorId: string
+    ): Promise<{
+        allowances: {
+            approved_for_all: boolean;
+        }[];
+    } | null>;
+
     /**
      * Get account by alias, id, or evm address.
      *

src/index.js

@@ -20,7 +20,7 @@ const { strict: assert } = require('assert');
 const debug = require('util').debuglog('hts-forking');
 
 const { ZERO_HEX_32_BYTE, toIntHex256 } = require('./utils');
-const { slotMapOf, packValues } = require('./slotmap');
+const { slotMapOf, packValues, persistentSlotMapOf } = require('./slotmap');
 const { deployedBytecode } = require('../out/HtsSystemContract.sol/HtsSystemContract.json');
 
 const HTSAddress = '0x0000000000000000000000000000000000000167';
@@ -138,11 +138,118 @@ async function getHtsStorageAt(address, requestedSlot, blockNumber, mirrorNodeCl
         return ret(ZERO_HEX_32_BYTE, `Token ${tokenId} not associated with ${accountId}`);
     }
 
-    const token = await mirrorNodeClient.getTokenById(tokenId, blockNumber);
-    if (token === null) return ret(ZERO_HEX_32_BYTE, `Token \`${tokenId}\` not found`);
-    const unresolvedValues = slotMapOf(token).load(nrequestedSlot);
-    if (unresolvedValues === undefined)
-        return ret(ZERO_HEX_32_BYTE, `Requested slot does not match any field slots`);
+    // Encoded `address(tokenId).getApproved(serialId)` slot
+    // slot(256) = `getApproved`selector(32) + padding(192) + serialId(32)
+    if (
+        nrequestedSlot >> 32n ===
+        0x81812fc_0000_0000_0000_0000_0000_0000_0000_0000_0000_0000_0000_0000n
+    ) {
+        const serialId = parseInt(requestedSlot.slice(-8), 16);
+        const { spender } =
+            (await mirrorNodeClient.getNftByTokenIdAndNumber(tokenId, serialId, blockNumber)) ?? {};
+        if (typeof spender !== 'string')
+            return ret(
+                ZERO_HEX_32_BYTE,
+                `NFT ${tokenId}#${serialId} is not approved to any address`
+            );
+        const account = await mirrorNodeClient.getAccount(spender, blockNumber);
+        if (account === null)
+            return ret(
+                ZERO_HEX_32_BYTE,
+                `NFT ${tokenId}#${serialId} is approved to address \`${spender}\`, failed to get its EVM Alias`
+            );
+
+        return ret(
+            account.evm_address,
+            `NFT ${tokenId}#${serialId} is approved to ${account.evm_address}`
+        );
+    }
+
+    // Encoded `address(tokenId).ownerOf(serialId)` slot
+    // slot(256) = `ownerOf`selector(32) + padding(192) + serialId(32)
+    if (
+        nrequestedSlot >> 32n ===
+        0x6352211e_0000_0000_0000_0000_0000_0000_0000_0000_0000_0000_0000_0000n
+    ) {
+        const serialId = parseInt(requestedSlot.slice(-8), 16);
+        const nft = (await mirrorNodeClient.getNftByTokenIdAndNumber(
+            tokenId,
+            serialId,
+            blockNumber
+        )) ?? {
+            account_id: null,
+        };
+        if (typeof nft['account_id'] !== 'string')
+            return ret(
+                ZERO_HEX_32_BYTE,
+                `Failed to determine an owner of the NFT ${tokenId}#${serialId}`
+            );
+        const account = await mirrorNodeClient.getAccount(`${nft['account_id']}`, blockNumber);
+        if (account === null)
+            return ret(
+                ZERO_HEX_32_BYTE,
+                `NFT ${tokenId}#${serialId} belongs to \`${nft['account_id']}\`, failed to get its EVM Alias`
+            );
+
+        return ret(
+            account.evm_address,
+            `NFT ${tokenId}#${serialId} is approved to ${account.evm_address}`
+        );
+    }
+
+    // Encoded `address(tokenId).isApprovedForAll(owner, operator)` slot
+    // slot(256) = `isApprovedForAll`selector(32) + padding(160) + ownerId(32) + operatorId(32)
+    if (nrequestedSlot >> 64n === 0xe985e9c5_0000_0000_0000_0000_0000_0000_0000_0000_0000_0000n) {
+        const operatorId = `0.0.${parseInt(requestedSlot.slice(-8), 16)}`;
+        const ownerId = `0.0.${parseInt(requestedSlot.slice(-16, -8), 16)}`;
+        const { allowances } = (await mirrorNodeClient.getAllowanceForNFT(
+            ownerId,
+            tokenId,
+            operatorId
+        )) ?? { allowances: [] };
+
+        if (allowances.length === 0)
+            return ret(
+                ZERO_HEX_32_BYTE,
+                `${tokenId}.isApprovedForAll(${ownerId},${operatorId}) not found`
+            );
+        const value = allowances[0].approved_for_all ? 1 : 0;
+        return ret(
+            `0x${value.toString(16).padStart(64, '0')}`,
+            `Requested slot matches ${tokenId}.isApprovedForAll(${ownerId},${operatorId})`
+        );
+    }
+
+    // Encoded `address(tokenId).tokenURI(serialId)` slot
+    // slot(256) = `tokenURI`selector(32) + padding(192) + serialId(32)
+    if (
+        nrequestedSlot >> 32n ===
+        0xc87b56dd_0000_0000_0000_0000_0000_0000_0000_0000_0000_0000_0000_0000n
+    ) {
+        const serialId = parseInt(requestedSlot.slice(-8), 16);
+        const { metadata } = (await mirrorNodeClient.getNftByTokenIdAndNumber(
+            tokenId,
+            serialId,
+            blockNumber
+        )) ?? {
+            metadata: null,
+        };
+        if (typeof metadata !== 'string')
+            return ret(
+                ZERO_HEX_32_BYTE,
+                `Failed to get the metadata of the NFT ${tokenId}#${serialId}`
+            );
+        persistentSlotMapOf(tokenId).store(nrequestedSlot, atob(metadata));
+    }
+    let unresolvedValues = persistentSlotMapOf(tokenId).load(nrequestedSlot);
+    if (unresolvedValues === undefined) {
+        const token = await mirrorNodeClient.getTokenById(tokenId, blockNumber);
+        if (token === null) return ret(ZERO_HEX_32_BYTE, `Token \`${tokenId}\` not found`);
+        unresolvedValues = slotMapOf(token).load(nrequestedSlot);
+
+        if (unresolvedValues === undefined)
+            return ret(ZERO_HEX_32_BYTE, `Requested slot does not match any field slots`);
+    }
     const values = await Promise.all(
         unresolvedValues.map(async ({ offset, path, value }) => ({
             offset,

src/slotmap.js

@@ -274,4 +274,60 @@ function slotMapOf(token) {
     return map;
 }
 
-module.exports = { slotMapOf, packValues };
+/**
+ * Represents the value in the `PersistentStorage`.
+ * Each token has its own SlotMap. Any value can be assigned to this storage
+ * ad-hoc. It can be used for dynamically determined keys needed to be persistent.
+ *
+ * @typedef {Object} PersistentStorage
+ * @property {SlotMap} slotMap - The SlotMap instance.
+ * @property {string} target - The target string.
+ */
+
+/**
+ * Represents the value in the `Storage`.
+ * Each token has its own SlotMap. Any value can be assigned to this storage
+ * ad-hoc. It can be used for dynamically determined keys needed to be persistent.
+ *
+ * @typedef {Object} PersistentSlotMap
+ * @property {function(bigint): Array<{
+ *   offset: number;
+ *   value:Value;
+ *   path:string;
+ *   type:string;
+ * }>|undefined} load - Loads the value associated with a slot.
+ * @property {function(bigint, string): void} store - Stores a value in the slot map.
+ */
+
+/**
+ * @type {Array<PersistentStorage>}
+ */
+const persistentStorage = [];
+
+/**
+ * Slot map of token, but persistent, will not be removed between multiple separate requests.
+ *
+ * @param {string} target
+ * @returns {PersistentSlotMap} An object with `load` and `store` methods.
+ */
+function persistentSlotMapOf(target) {
+    const found = persistentStorage.filter(occupiedSlot => occupiedSlot.target === target);
+    const initialized = {
+        target,
+        slotMap: found.length > 0 && found[0] ? found[0].slotMap : new SlotMap(),
+    };
+    persistentStorage.push(initialized);
+    return {
+        load: slot => initialized.slotMap.load(slot),
+        store: (slot, value) =>
+            visit(
+                { label: 'value', slot: slot.toString(), type: 't_string_storage', offset: 0 },
+                0n,
+                { value },
+                '',
+                initialized.slotMap
+            ),
+    };
+}
+
+module.exports = { packValues, persistentSlotMapOf, slotMapOf };