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https://github.com/dapplion/giveth-funds-forwarder

Intermediate contract to allow donations from DAOs or other contracts to Giveth milestones via its bridge.
https://github.com/dapplion/giveth-funds-forwarder

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Intermediate contract to allow donations from DAOs or other contracts to Giveth milestones via its bridge.

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# Giveth Funds Forwarder



[![Build Status](https://travis-ci.com/dapplion/giveth-funds-forwarder.svg?branch=master)](https://travis-ci.com/dapplion/giveth-funds-forwarder)

[![Coverage Status](https://coveralls.io/repos/github/dapplion/giveth-funds-forwarder/badge.svg)](https://coveralls.io/github/dapplion/giveth-funds-forwarder)



[Mainnet deploy ↗](https://etherscan.io/address/0xa04d4f31c2aaceae21279f4c1143741625d79efb#code)



Intermediate contract to allow donations from DAOs or other contracts to Giveth milestones via its bridge.



```

        Funds Forwarder Factory

                  ||

                  || deploy(receiverId)

                  \/

DAO ======> Funds Forwarder ======> Bridge ======> Milestone

    send ETH           forward(receiverId)

  transfer Token

```



The `FundsForwarder` is meant to be a proxy deployed by its factory `FundsForwarderFactory`. The current implementation uses [EIP 1167](https://github.com/ethereum/EIPs/blob/master/EIPS/eip-1167.md), a technique to deploy forwarding proxies (not upgradable) at very low gas costs. The `FundsForwarder` incorporates the [Initializable](https://hack.aragon.org/docs/common_Initializable) and [Petrifiable](https://hack.aragon.org/docs/common_Petrifiable) scheme used by [Aragon](https://github.com/aragon/aragonOS) to freeze the original logic contract and control proxy initialization. The initialization is done atomically in one transaction by the `FundsForwarderFactory`. The `FundsForwarder` contract also incorporates functionality from the Escapable contract by Jordi Baylina and Adrià Massanet to allow recovery of funds as a last resort if a security issue is uncovered.



## How to use it (front-end reference)



### Create a new funds forwarder



A revelant individual of a specific milestone or campaing should be shown a button "Create donation address" that calls `FundsForwarderFactory.newFundsForwarder(uint64 _giverId, uint64 _receiverId)`



The address of this contract will be constant and determined after deployment, so it should be hardcoded in the code.



**Sample code**



```js

import web3 from "./web3GetterOrSomething";

import fundsForwarderFactoryAbi from "contracts/fundsForwarderFactoryAbi.json";



const fundsForwarderFactoryAddress = "ALREADY_KNOWN";



const fundsForwarderFactory = web3.eth.Contract(

  fundsForwarderFactoryAbi,

  fundsForwarderFactoryAddress

);



async function createDonationAddress() {

  const receipt = await fundsForwarderFactory.methods

    .newFundsForwarder(giverId, receiverId)

    .send();



  const newFundForwarderEvent = receipt.events.find(

    ({ event }) => event === "NewFundForwarder"

  );

  const donationAddress = newFundForwarderEvent.returnValues.fundsForwarder;

  return donationAddress;

}

```



**Address** ([etherscan](https://etherscan.io/address/0xa04d4f31c2aaceae21279f4c1143741625d79efb#code))



Main mainnet deploy. Notice that there can be multiple factories.



```

0xA04D4F31c2aAcEAe21279f4C1143741625D79eFb

```



**ABI**



```json

[

  {

    "anonymous": false,

    "inputs": [

      {

        "indexed": true,

        "name": "_giver",

        "type": "address"

      },

      {

        "indexed": true,

        "name": "_receiverId",

        "type": "uint64"

      },

      {

        "indexed": false,

        "name": "fundsForwarder",

        "type": "address"

      }

    ],

    "name": "NewFundForwarder",

    "type": "event"

  },

  {

    "constant": false,

    "inputs": [

      {

        "name": "_giverId",

        "type": "uint64"

      },

      {

        "name": "_receiverId",

        "type": "uint64"

      }

    ],

    "name": "newFundsForwarder",

    "outputs": [],

    "payable": false,

    "stateMutability": "nonpayable",

    "type": "function"

  }

]

```



### Send funds to the funds forwarder



Regular ethereum token or ETH transaction



### Forward funds to the bridge



The UI should query the balance of each funds forwarder contract of the milestones that the user is insterested in.



If a sufficient balance of one or multiple tokens is found for a giveth funds forwarder contract, the front end should alert the user and offer a button "Forward to the Bridge" or "Collect donations". This button should trigger the function `FundsForwarder.forwardMultiple(address[] _tokens)`.



**Sample code**



```js

import web3 from "./web3GetterOrSomething";

import fundsForwarderAbi from "contracts/fundsForwarderAbi.json";

import erc20Abi from "contracts/erc20Abi.json";



const whitelistedTokens = [

  "0xdac17f958d2ee523a2206206994597c13d831ec7",

  "0xB8c77482e45F1F44dE1745F52C74426C631bDD52",

  "0x2af5d2ad76741191d15dfe7bf6ac92d4bd912ca3",

  "0x514910771af9ca656af840dff83e8264ecf986ca",

  "0x9f8f72aa9304c8b593d555f12ef6589cc3a579a2"

];



const minimumBalanceToForward = web3.utils.toWei("0.1");



async function forwardToTheBridge(fundsForwarderAddress) {

  const tokensToForward = [];



  for (const tokenAddress of whitelistedTokens) {

    const erc20 = web3.eth.Contract(erc20Abi, tokenAddress);

    const balance = await erc20.methods.balanceOf(fundsForwarderAddress).call();

    if (balance > minimumBalanceToForward) tokensToForward.push(tokenAddress);

  }



  if (!tokensToForward.length) return;



  const fundsForwarder = web3.eth.Contract(

    fundsForwarderAbi,

    fundsForwarderAddress

  );



  await fundsForwarder.methods.forwardMultiple(tokensToForward).send();

}

```



**Address**



```

Fetched dynamically

```



**ABI**



```json

[

  {

    "constant": false,

    "inputs": [

      {

        "name": "_tokens",

        "type": "address[]"

      }

    ],

    "name": "forwardMultiple",

    "outputs": [],

    "payable": false,

    "stateMutability": "nonpayable",

    "type": "function"

  }

]

```



## Gas costs



| Action                                        | Gas cost  | Frequency                                          |

| --------------------------------------------- | --------- | -------------------------------------------------- |

| Deploy FundsForwarderFactory (w/ child logic) | 3,654,402 | Once                                               |

| Deploy FundForwarder                          | 117,087   | Once for each applicable milestone                 |

| Forward ETH to bridge                         | 39,297    | Every time each milestone requires the funds       |

| Forward Tokens (DAI) to bridge                | 78,596    | First time each milestone requires the funds       |

| Forward Tokens (DAI) to bridge                | 39,103    | Every other time each milestone requires the funds |

| Forward multiple tokens (ETH, DAI, FAKEERC20) | 80,660    | -                                                  |



Gas costs without proxy are: Deploy FundForwarder +1,317%, Forward ETH to bridge -2%, Forward Tokens to bridge -1%.



## How to deploy



Only one contract has to be deployed (`FundsForwarderFactory`), which will deploy the logic of the child contract and do all the setup actions.



The flattened code of the contract is ready to be copy / pasted to remix and can be found in [flattened_contracts/FundsForwarderFactory.sol](flattened_contracts/FundsForwarderFactory.sol). If the code is re-compiled from source, use solidity version `0.4.24+commit.e67f0147` and enable the optimizer.



The arguments for the constructor are:



| Argument                 | Value                                                                                                                   |

| ------------------------ | ----------------------------------------------------------------------------------------------------------------------- |

| \_bridge                 | [`0x30f938fED5dE6e06a9A7Cd2Ac3517131C317B1E7`](https://etherscan.io/address/0x30f938fed5de6e06a9a7cd2ac3517131c317b1e7) |

| \_escapeHatchCaller      | [`0x1e9F6746147E937E8E1C29180e15aF0bd5fd64bb`](https://etherscan.io/address/0x1e9f6746147e937e8e1c29180e15af0bd5fd64bb) |

| \_escapeHatchDestination | [`0x16Fda2Fcc887Dd7Ac65c46Be144473067CfF8654`](https://etherscan.io/address/0x16fda2fcc887dd7ac65c46be144473067cff8654) |

| \_childImplementation    | 0x0000000000000000000000000000000000000000                                                                              |



**SECURITY NOTE**: The FundsForwarderFactory contract will immediately grant its ownership to the bridge owner. The address deploying the contract will have no special priviledges on the FundsForwarderFactory and FundsForwarders at any time.



**RE-REPLOYMENT NOTE**: If you want to deploy a second FundsForwarderFactory contract and not re-deploy the childImplementation, you must pass its address as a contructor argument, and you should modify the FundsForwarder code from the FundsForwarderFactory to save around ~1,500,000 gas on deployment.