Ethereum Blobs Utils

blobs-utils.mjs

import { bytesToString, hexToBytes } from 'viem';

export async function getBlobMeta(hash) {
	let result = {};

	try {
		const res = await fetch(getBlobUrl(hash)).then((x) => x.json());

		if (res.error) {
			result.error = res.error;

			return result;
		}

		result.data = res.result.data.json;

		const { transactionsWithBlocks, versionedHash: blobVersionedHash } = result.data;

		delete result.data.transactionsWithBlocks;
		delete result.data.versionedHash;

		const tx = transactionsWithBlocks[0];

		result.data = { ...tx, blobVersionedHash, ...result.data };

		return result;
	} catch (er) {
		result.error = { message: er.message, code: 'FETCHING_BLOB_METADATA_FAILED' };
	}

	return result;
}

export function getBlobUrl(blobVersionedHash) {
	return `https://blobscan.com/api/trpc/blob.getByBlobIdFull?input=${JSON.stringify({
		json: { id: blobVersionedHash },
	})}`;
}

// NOTE: accept transaction hash, or blob hash (blobVersionedHash) which is the same as transaction hash but with 0x01 prefix
export async function getBlob(hash, options = {}) {
	let { withContent = true, withoutInput = false } = { ...options };

	withContent = Boolean(withContent);
	withoutInput = Boolean(withoutInput);

	if (hash.startsWith('0x') && hash.length === 66 && !hash.startsWith('0x01')) {
		const getUrl = (txhash) => `https://api.blobscan.com/transactions/` + txhash;
		try {
			hash = await fetch(getUrl(hash))
				.then((x) => x.json())
				.then((x) => x.blobs[0]);
		} catch (e) {
			hash = 'err data';
		}
	}

	if (!hash.startsWith('0x01') && hash.length !== 66) {
		return { error: { message: 'invalid blob hash' } };
	}

	const blobMeta = await getBlobMeta(hash);

	if (blobMeta.error) {
		console.log('error:', blobMeta.error);
		return blobMeta;
	}

	const input = blobMeta.data.data;
	delete blobMeta.data.data;
	delete blobMeta.data.size;

	if (!withoutInput) {
		blobMeta.data.input = input;
	}

	if (withContent || blobMeta.data.input.startsWith('0x00646174613a')) {
		blobMeta.data.content = cleanHexData(input).trim().replace(/\0/g, '');
		blobMeta.data.contentSize = blobMeta.data.content.length;
	}

	return blobMeta;
}

export function cleanHexData(input) {
	const u8 = typeof input === 'string' ? hexToBytes(input) : input;
	const bytes = [] as any;

	u8.forEach((x, i) => {
		if (i === 0) return;

		if (parseInt(String(x), 16)) {
			bytes.push(x);
		}
	});

	return bytesToString(Uint8Array.from(bytes.slice(0, -1)));
}