solidity-by-example.github.io

TODO: simplify bi directional payment channel

Solidity By Example

License

MIT License

Basic - 0

• hello world
• first application (counter app)
• primitives (uint, bytes32, address...)
• variables (local, state, global)
• getters and setters (tx)
• ether and wei
• gas and gas price

Basic - 1

Flow control

• if / else (TODO: ternary)
• for loop

Data types

• mapping
  • CRUD
  • nested
  • not iterable
• array
  • fixed size / dynamic size
  • CRUD
  • delete element (compact)
• TODO?: string and bytes
• enum
• structs
• data locations - storage, memory, calldata

Function

• function

• view and pure functions

• error

• function modifiers

• events

Inheritance

• constructor
• inheritance
• shadowing state variables
• calling parent contracts
• visibility
• interface

Sending and Receiving Ether

• payable
• send ether from contract
• fallback

Contract Interaction

• call
• delegate call
• calling other contracts
• creating contract from a contract (pre: calling other contract)

Misc

• import
• library
• TODO? assembly

Cryptography

• hash function
• signature verification

Application

• multisig wallet
• erc20
• iterable mapping
• merkle tree
• create2
• payment channels (uni, bidirectional)
• TODO?: casper?
• TODO?: minimal proxy contract?

Hacks

• reentrancy
• arithmetic overflow / underflow
• unexpected ether (self destruct)
• read private data
• delegatecall (pre: storage layout)
• default visibility (skip)
• entropy illusion
• external contract referencing
• honeypot (pre: external call & reentrancy)
• short address / param attack (skip)
• unchecked call return value (skip)
• front running
• DOS
• block timestamp manipulation
• constructor with care (skip)
• unintializsd storage pointers (skip)
• floating points and precisions (skip)
• tx.origin

Ethernaut

• hello ethernaut
• fallback
• fallout (constructor with care)
• coin flip (randomness guessing head / tail based on prev block hash)
• telephone
• token
• delegation (delegatecall to change ownership)
• force
• vault (read private data)
• king
• re-entrancy
• elevation
• privacy (optimized storage)
• gatekeeper one
• gatekeeper two
• naught coin
• preservation (delegatecall to change address and then ownership)
• recovery
• magic number (contract creation)
• alien codex (edit ABI)
• denial (denial of service using assert and using up all gas)
• shop (external contract call)

Patterns

• push vs pull
• commit reveal
• factory

TODO

• search
• build pipeline (.gitignore index.html.js and rebuild it when deploy)
• exercises
• sidenav and or link to next topic
• seo
• submarine send

0.6 memo

• script to generate routes

• redirect to current page for 0.5 and 0.6

• typescript

• override and virtual

• shadow disallowed

• fallback and receive

• 0.6 features

Memo

# deploy
npm run deploy

# find and compile sol
find src/pages/0.6 -name "*.sol" -exec docker run -v $PWD/src:/src ethereum/solc:0.6.0 {} \;

# compile single file
docker run -v $PWD/src:/src ethereum/solc:0.6.0 /src/pages/0.6/sol/HelloWorld/HelloWorld.sol

# md to react
npm run md-to-react -- path/to/folder/with/md

# md to react all pages
find src -type d -not -path "*/__snapshots__" -exec npm run md-to-react -- {} \;