[BUG] snarkyjs 0.2.0 allows multiple snapps to be deployed to the same address with shared state

more-snapps-per-address.ts

import {
  Field,
  isReady,
  method,
  Mina,
  Party,
  PrivateKey,
  PublicKey,
  shutdown,
  SmartContract,
  state,
  State,
  UInt64,
} from 'snarkyjs';

class Squared extends SmartContract {
  @state(Field) value = State<Field>();

  constructor(initialBalance: UInt64, address: PublicKey, x: Field) {
    super(address);
    this.balance.addInPlace(initialBalance);
    this.value.set(x);
  }

  @method
  async update(squared: Field) {
    const x = await this.value.get();
    x.square().assertEquals(squared);
    this.value.set(squared);
  }
}

class Cubed extends SmartContract {
  @state(Field) value = State<Field>();

  constructor(initialBalance: UInt64, address: PublicKey, x: Field) {
    super(address);
    this.balance.addInPlace(initialBalance);
    this.value.set(x);
  }

  @method
  async update(cubed: Field) {
    const x = await this.value.get();
    x.square().mul(x).assertEquals(cubed);
    this.value.set(cubed);
  }
}

async function runSimpleApp() {
  await isReady;

  const Local = Mina.LocalBlockchain();
  Mina.setActiveInstance(Local);
  const sender = Local.testAccounts[0].privateKey;
  const sponsor = Local.testAccounts[1].privateKey;
  const badActor = Local.testAccounts[2].privateKey;
  const badSponsor = Local.testAccounts[3].privateKey;

  const snappPrivkey = PrivateKey.random();
  const snappPubkey = snappPrivkey.toPublicKey();

  let squaredInstance: Squared;
  let cubedInstance: Cubed;

  // Deploys the snapp
  await Mina.transaction(sender, async () => {
    // sponsor sends 1000000000 to the new snapp account
    const amount = UInt64.fromNumber(1000000000);
    const p = await Party.createSigned(sponsor);
    p.balance.subInPlace(amount);

    squaredInstance = new Squared(amount, snappPubkey, new Field(3));
  })
    .send()
    .wait();

  console.log('initial state after deployment 3 ==', (await Mina.getAccount(snappPubkey)).snapp.appState[0].toString());

  // Update the snapp
  await Mina.transaction(sender, async () => {
    // 9 = 3^2
    await squaredInstance.update(new Field(9));
  })
    .send()
    .wait();

  console.log('initial state after deployment 9 ==', (await Mina.getAccount(snappPubkey)).snapp.appState[0].toString());

  await Mina.transaction(sender, async () => {
    // Fails, because the provided value is wrong.
    await squaredInstance.update(new Field(109));
  })
    .send()
    .wait()
    .catch((e) => console.log('second update attempt failed'));


  console.log('state does not change after bad call 9 ==', (await Mina.getAccount(snappPubkey)).snapp.appState[0].toString());

  // Deploys a different Snapp to the same address with new initial state.
  // BUG!!! this should not be allowed??
  await Mina.transaction(badActor, async () => {
    // sponsor sends 1000000000 to the new snapp account
    const amount = UInt64.fromNumber(1000000000);
    const p = await Party.createSigned(badSponsor);
    p.balance.subInPlace(amount);

    cubedInstance = new Cubed(amount, snappPubkey, Field(2)); // BUG!!! this new state overrides the existing state
  })
    .send()
    .wait();

  console.log('state value after redeploy 2 == ', (await Mina.getAccount(snappPubkey)).snapp.appState[0].toString());

  // Calling the new snapp also works
  await Mina.transaction(sender, async () => {
    await cubedInstance.update(new Field(2 * 2 * 2));
  })
    .send()
    .wait();
  console.log('calling new contract also works 8 ==', (await Mina.getAccount(snappPubkey)).snapp.appState[0].toString());

  // Calling the old snapp still works, but with the new state
  // this is also bad because the good actors are unaware how the state has been updated
  await Mina.transaction(sender, async () => {
    await squaredInstance.update(new Field(8 * 8));
  })
    .send()
    .wait();
  console.log('calling old contract still works 64 ==', (await Mina.getAccount(snappPubkey)).snapp.appState[0].toString());
}

runSimpleApp();

shutdown();

This demonstrates how to reproduce the bug reported in snarkyjs