This project is a simple implementation of a blockchain in a peer-to-peer (P2P) network using the Go programming language and the libp2p library.
Open a web browser and go to the official Go website: https://golang.org/dl/
On the downloads page, find the section for Linux and click on the download link for the latest stable version of Go. Choose the appropriate package for your system architecture (either 32-bit or 64-bit).
Once the download is complete, open a terminal window.
Navigate to the directory where the downloaded Go package is located. For example, if it's in the "Downloads" directory, you can use the following command:
cd ~/Downloads Extract the downloaded package using the following command:
sudo tar -C /usr/local -xzf go.linux-.tar.gz Replace with the Go version number you downloaded (e.g., 1.16.3) and with your system architecture (e.g., amd64).
Next, you need to set up the Go environment variables. Open the .profile file in a text editor using the following command:
sudo nano ~/.profile Add the following lines to the end of the file:
export PATH=$PATH:/usr/local/go/bin export GOPATH=$HOME/go export PATH=$PATH:$GOPATH/bin These lines add the Go binary directory to the system's PATH variable and set up the GOPATH environment variable.
Save the file and exit the text editor.
To apply the changes, run the following command:
source ~/.profile Verify that Go is installed correctly by opening a new terminal window and running the following command:
go version You should see the installed Go version printed in the terminal.
The blockchain is a chain of blocks, where each block contains data. In this case, the data represents a product with an ID, location, and owner. The blockchain is stored in a slice of Block structs. The network of nodes is managed using the libp2p library, which allows for P2P communication.
Each block in the blockchain is represented by a Block struct:
type Block struct { ha host.Host Index int Timestamp string ProductID string Location string Owner string Hash string PrevHash string Validator string }
A Proposal struct is used to represent a proposal for a new node to be added to the network:
type Proposal struct { NodeID string Votes int }
The makeBasicHost function is used to create a basic libp2p host. A libp2p host is a node in the network that can communicate with other nodes. The function takes a listen port, a boolean indicating whether to use secio (a secure transport), and a seed for generating a random ID for the host.
The handleStream function is a stream handler that is called when a new stream is opened between hosts in the network. It reads and writes data to and from the stream.
The readData function reads data from a stream. It unmarshals the received data into a slice of Block structs and replaces the current blockchain with the received one if it's longer.
The writeData function writes the current blockchain to a stream every 5 seconds. It also reads input from the user to add new blocks to the blockchain.
The isBlockValid function checks if a block is valid by comparing it to the previous block. A block is considered valid if its index is one more than the previous block's index, its PrevHash field is equal to the previous block's Hash field, and its hash is correctly calculated.
The isNodeAuthorized function checks if a node is authorized by comparing its ID to the IDs in the AuthorizedNodes slice.
The calculateHash function calculates the SHA-256 hash of a block.
The generateBlock function generates a new block based on the previous block and the provided data.
go run main.go -l <listen_port> Replace <listen_port> with the port number you want the node to listen on.
go run main.go -l <listen_port> -d <target_address> Replace <target_address> with the address of the node you want to connect to.