khawlahssn/blockchain-developer-bootcamp-final-project

ConsenSys Blockchain Developer Bootcamp 2021 Final Project.

Final Project - Recycling Reward System

App Link

https://khawlahssn.github.io/blockchain-developer-bootcamp-final-project/

Screencast

https://www.youtube.com/watch?v=i6o3O2WV0mE

Ethereum Address for Certification

0x8D7544695d6aBDb17891180F53cD821a27dbFff0

Running the project locally

Pre-requisties

• Node.js >= 14
• Truffle and Ganache
• Yarn

Contracts

• yarn install
• Development network is Ganache running locally on port 7545 and has a network id of 5777
• truffle develop
• To deploy the contract on Ganache: migrate --development
• To run the tests: test
• To deploy the contract to a testnet, please change the address passed to the contructor in the migrations directory to any address of your own to be able to make the reward requests

Front-end

• cd client
• yarn install
• yarn start launches a react app that can viewed in your browser at http://localhost:3000

Project Structure

.
├── ./README.md
├── ./avoiding_common_attacks.md
├── ./build
│   └── ./build/contracts
├── ./client
│   ├── ./client/README.md
│   ├── ./client/build
│   ├── ./client/node_modules
│   ├── ./client/package.json
│   ├── ./client/public
│   ├── ./client/src
│   └── ./client/yarn.lock
├── ./contracts
│   ├── ./contracts/Migrations.sol
│   └── ./contracts/Recycle.sol
├── ./deployed_address.txt
├── ./design_pattern_decisions.md
├── ./log.txt
├── ./migrations
│   ├── ./migrations/1_initial_migration.js
│   └── ./migrations/2_deploy_contract.js
├── ./node_modules
├── ./package.json
├── ./test
│   ├── ./test/exceptionsHelpers.js
│   └── ./test/recycle.test.js
├── ./truffle-config.js
└── ./yarn.lock

Transaction Flow

1. User submits a description of their item and specify their location
2. Based on the drop-off location given to the user, the assigned e-waste collector will recieve the item, measures it, and submits a request to the admin
3. The user's and collector's measurements should be equal after rounding
4. Admin/authority recevies the request from the collector then rewards the recycler with 0.001 ether

Project Description

E-waste consists of electrical and electronic equipments (EEEs) that have been discarded by their owners because they're either unwanted or have reached the end of their useful life. According to the UN, the world produces about 50 million tonnes a year of e-waste and only 20% is formally recycled with 80% either ending up in landfill or being informally recycled. EEEs are made of components that have large amounts of heavy metals and toxic substances such as lead and mercury which is why it is so damaging to the environment and has a negative effect on human health. The cheapest recyling option for many countries is to send e-waste overseas to developing countires, hence putting the workers health at risk.

The objective of the project is to incentivise people to recycle their e-waste, this can be done as follows:

1. A goverment authority (for example. ministry of climate change & environment) will be responsible for creating, running, and maintaining the network in addition to writing the smart contracts
2. Consumer will put up their e-waste for recycling which will then be collected by a waste collector
3. The waste collector delivers the items to a recycling facility which then confirms the transaction, weighs the equipments, and depending on the weight the consumer will be rewarded with an x-amount of ether. Also, they can recieve an NFT appreciation card for their contribution in protecting the environment if they for example put up over 100 items for recycling
4. The GA must approve the transfer of eth before it gets sent to the consumer's address

Environment variables for deploying on a testnet

• ACCOUNT_MNEMONIC=
• RINKEBY_ENDPOINT=

To-do features

• rewardCard() that will mint an NFT appreciation card for when over a 100 items are recycled
• Instead of having the amountToAward fixed, it checks the current value of around 10$ in ether

blockchain-developer-bootcamp-final-project's Issues

Initial Feedback

The project's UI is very slick and works well. Consider adding a "switch to rinkeby" button if not on the correct chain.

One thing I did notice is a reentrancy security flaw with the following:

recyclerAddress.transfer(valueToReward);
recyclerInfo[_recycler].itemStatus = State.Rewarded;

If the attacker was a contract address, on the transfer (best practice now is to use .call as well), it could call back and the State would still be unchanged. Recursively this could drain the contact until it ran out of ETH.

Consider swapping the two lines around.

Overall, well done - it looks great and works well.