Zincir

Simple distributed blockchain experiment written in Crystal

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Usage

Build

To build zincir, you will need Crystal and OpenSSL installed on your system. You can use Homebrew on Mac to install these dependencies.

> git clone git@github.com:oguzbilgic/zincir-crystal.git
  ...
> shards install
  ...
> shards build --release
  Dependencies are satisfied
  Building: zincird

Options

> ./bin/zincird --help
  Usage: zincir [arguments]
      -s IP, --seed-ip=IP              First node to connect, TestNet by default
      -i IP, --host-ip=IP              Node's public ip, If the node is public
      -p PORT, --port=PORT             Node's public port, If the node is public
      -l, --local-net                  Prevents node from connecting to public nodes
      -w, --web                        Start web server without making the node public
      -m, --mine                       Enable mining
      -h, --help                       Show this help
      -v, --version                    Show node version

Start

> ./bin/zincird --mine
  Connecting to testnet.zincir.xyz:9147
  Added <1-0878bff02..ec7> 1544946023
  ...

Node will connect to TestNet by default and sync the blockchain, before mining. Blockchain will be cached in ./blocks/ folder.

Start a public node

> ./bin/zincird --ip mynode.mywebsite.com --port 1234 --mine
  Connecting to testnet.zincir.xyz:9147
  Added <1-0878bff02..ec7> 1544946023
  ...

In public mode, node will advertise it's ip and host to the network for other nodes to connect. Therefore, node needs to be publicly accessible with the provided ip and port configuration

Development

High Level Overview

• Read and add cached blocks from .blocks/ folder to blockchain. Whenever a new block is added to the chain, store it in the .blocks/ folder
• Unless --local-net is set, connect to seed host (testnet by default, can be updated with --seed-ip option)
  • Compare our last block to network's last block
  • Find the highest common block between network and local
  • If network has a higher last block download all blocks between common_block and network's last block
  • If our last block is higher, broadcast all blocks between the common_block and our last block
  • Once the network download or broadcast is complete, wait for 5 seconds and compare local and network last block's to ensure network and local is synced
• If --web or --port option is provided start local web server
• If --host-ip option is provided start public web server and broadcast our ip to all the connected hosts.
• If --mine option is set start the miner to mine new blocks. When a new block is mined broadcast it to network

Run tests

> crystal spec
  ...