A toy implementation of a tcp server with its own simple text protocol with content protection from ddos attacks using proof of work.
The project consists of a tcp server and a tcp client.
The server offers to solve the proof of work problem to the client in order to access the content.
The client receives the problem, solves it, and receives a quote from Words of wisdom.
- go1.18
- golangci-lint
Install from local go toolkit Go 1.18
go install ./cmd/powwy-srv
go install ./cmd/powwy-cli
make buildsudo docker build -it powwy-cli -f ./docker/client.Dockerfile .
sudo docker build -it powwy -f ./docker/server.Dockerfile .
sudo docker run powwy --net=host -p 3333:3333
sudo docker run powwy-cli -a localhost:3333 -d // infinite loop
sudo docker run powwy-cli compute <header>From docker hub
docker pull robotomize/powwy-cli:latest
docker pull robotomize/powwy-srv:latestsudo docker-compose upFind a solution to the HashCash header problem
powwy-cli compute <header1> <header2> Usage: powwy-cli compute <header> <header> <header>
Usage:
compute [flags]
Flags:
-h, --help help for compute
Global Flags:
-d, --duration duration -d 10s (default -1ns)
-i, --iterations int -i 1000000 (default -1)
-w, --workers int -w 4 (default 2)Connect to powwy server and fetch quotes
powwly-cli -a localhost:3333Usage:
Available Commands:
completion Generate the autocompletion script for the specified shell
compute Usage: powwy-cli compute <header> <header> <header>
help Help about any command
Flags:
-a, --addr string -a localhost:3333 (default "localhost:3333")
-s, --dos -s true
-d, --duration duration -d 10s (default -1ns)
-h, --help help for this command
-i, --iterations int -i 1000000 (default -1)
-n, --network string -n tcp4 (default "tcp")
-w, --workers int -w 4 (default 2)
Use " [command] --help" for more information about a command.The http://www.hashcash.org/ algorithm was chosen to implement the proof of work mechanism
Pros:
- Easy to find description
- Easy to implement
Cons:
- Difficult to adjust the difficulty of the task
HashCashHeader: version:difficult:expiredAt:subject:alg:nonce:counter
- version - version of the header, represented by an int
- difficult - the complexity of the useful work, expressed in the number of first zeros of the hash
- expiredAt - the lifetime of the task, after which it is considered invalid
- subject - defines the name of the resource or other identifying information, such as a user ID or its ip address
- alg - determines what type of hash to use
- nonce - is a randomly generated set of bytes
- counter - Current counter value
Example 1:20:1665396610:localhost:sha-512:hVscDCMZcS1WYg==:BQAAAAAAAAA=
Pros: Works great for decentralized applications
Cons: Not very suitable for the implementation of client-server applications
powwy uses a simple command text protocol
List of available commands
// Proto specification tags
const (
REQ = "REQ" // REQ - request challenge
RES = "RES" // RES - request resource
RSV = "RSV" // RSV - response with payload
OK = "OK" // OK - command accepted
ERR = "ERR" // ERR - command err
DISC = "DISC" // DISC - initialize close connection
)Format:
<Command> <body length> |<body>
or
<Command>
Example:
---------------------------------------------------------------------------------------------------------------
UNKNOWN_COMMAND
ERR 18 |command wrong
---------------------------------------------------------------------------------------------------------------
REQ
ERR 21 |internal server error
---------------------------------------------------------------------------------------------------------------
REQ
RSR 62 |<token>
1:5:1665396610:localhost:sha-256:vZOxuoIgixP+hw==:AAAAAAAAAAA=
---------------------------------------------------------------------------------------------------------------
RES 62 |<token>
1:5:1665396610:localhost:sha-256:vZOxuoIgixP+hw==:FxUQAAAAAAA=
RST 139 |Voice is not just the sound that comes from your throat, but the feelings that come from your words.
― Jennifer Donnelly, A Northern Light
---------------------------------------------------------------------------------------------------------------
DISC
OK
---------------------------------------------------------------------------------------------------------------