8

From the yellow paper, I figured out that a contract has 4 components 1. nonce, 2. balance, 3. code, 4. storage. To know about the current state of a smart contract we need to know the all these components of a smart contract.

If I am using a geth client to get the state of smart contract, I can use

1.eth.getBalance(address) to get the balance of a contract

2.eth.getCode(address) to get the code of a contract

3.eth.getTransactionCount(address) for nonce

4.And similarly, eth.getStorageAt(address, index) to fetch the storage at a particular index.

I could neither find a way to download the complete storage at once nor a way to download the complete state of the contract directly.

So are there any way to get the full state of a contract?

Question regarding complete state has been asked here but the answers are not very helpful.

10

There is no way to do it via JSON RPC or with web3 API.

I've created a repository on Github with an example showing how to read all Patricia trie entries in a block and in any contract storage using nodejs https://github.com/medvedev1088/ethereum-merkle-patricia-trie-example

var Trie = require('merkle-patricia-tree');
var rlp = require('rlp');
var levelup = require('levelup');
var leveldown = require('leveldown');
var db = levelup(leveldown('/your_home_dir/Library/Ethereum/rinkeby/geth/chaindata'));
var keccak256 = require('js-sha3').keccak256;

// the block state root, rinkeby, block number 1775804
// the block state root can be obtained by invoking web3.eth.getBlock(<blockNumber>) in `stateRoot` field
var root = '0xe4a6ff741ec2e0d0cd274a745756028df27312161bdb4557b6da434349f716a9';
var trie = new Trie(db, root);

trie.checkRoot(root, function (err, val) {
  console.log('Root exists:', val);
});

var address = '398A7A69f3c59181A1ffe34bed11DCb5DF863A8a';
var addressHash = keccak256(new Buffer(address, 'hex'));

trie.get('0x' + addressHash, function (err, val) {
  var decodedVal = rlp.decode(val);
  console.log(decodedVal);

  if (!decodedVal || decodedVal.length < 4) {
    console.log('The value for the address must be an array of 4 elements');
    return;
  }

  // 3rd element in the array is storage root, 1st - nonce, 2nd - balance, 4th - codeHash
  var storageRoot = decodedVal[2];
  console.log('storageRoot', storageRoot);

  trie.root = storageRoot;

  trie.checkRoot(storageRoot, function (err, val) {
    console.log('Storage root exists:', val);
  });

  // Read storage slot with index 0

  var slotZeroHash = keccak256(new Buffer('0000000000000000000000000000000000000000000000000000000000000000', 'hex'));
  trie.get('0x' + slotZeroHash, function (err, val) {
    var decodedVal = rlp.decode(val);
    console.log('Value at slot 0: ', decodedVal);
  });

  // Read all entries from contract storage

  var stream = trie.createReadStream();

  stream.on('data', function (data) {
    console.log('key:' + data.key.toString('hex'));

    // values are rlp encoded
    var decodedVal = rlp.decode(data.value);
    console.log(decodedVal);
  });

  stream.on('end', function (val) {
    console.log('done reading!');
  });
});

Example output:

Root exists: true
Account data: 398A7A69f3c59181A1ffe34bed11DCb5DF863A8a [ <Buffer 01>,
  <Buffer >,
  <Buffer 24 21 83 63 90 de b4 32 ce 0e ac fe 5f 49 be 88 99 17 bf 8a fa 07 72 24 1c 30 9e 61 e0 4a 0d 42>,
  <Buffer 61 60 55 49 c9 7c 3e 7a d6 68 63 3b 72 b2 60 d3 00 5e ab be f3 22 a2 d6 33 2a 49 76 80 89 77 7a> ]
Storage root: <Buffer 24 21 83 63 90 de b4 32 ce 0e ac fe 5f 49 be 88 99 17 bf 8a fa 07 72 24 1c 30 9e 61 e0 4a 0d 42>
Storage root exists: true
Value at slot 0 - key: 290decd9548b62a8d60345a988386fc84ba6bc95484008f6362f93160ef3e563
<Buffer 40 9f 9c d8 52 a3 ba e9 52 5d 2a aa>
key:0205d9ce8b4a26409d40486b0ac7b8dc356714e840016b19cc5c0f2c8adbcd74
<Buffer 36 35 c9 ad c5 de a0 00 00>
key:0249d346d51fad5ef0b6fae89b4907e63c831f4f8af088d602baef47cda4eab7
<Buffer 0a 07 64 07 d3 f7 44 00 00>

Interestingly, this data is almost useless because you don't know the slot indexes (you can only see their hashes) and don't know data types of values. At least you know how much storage is occupied by a contract.

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