README, COPYING, fix and precision

COPYING

@@ -0,0 +1,13 @@
+DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+        Version 2, December 2004
+
+Copyright (C) 2004 Sam Hocevar <sam@hocevar.net>
+
+Everyone is permitted to copy and distribute verbatim or modified
+copies of this license document, and changing it is allowed as long
+as the name is changed.
+
+DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+0. You just DO WHAT THE FUCK YOU WANT TO.

Makefile

@@ -1,31 +1,32 @@
 mkfile_path := $(dir $(abspath $(lastword $(MAKEFILE_LIST))))
-version := $(git tag -l | tail -n 1)
+build_path := $(mkfile_path)build/
+version := $$(git tag -l | tail -n 1)
 
 help:
 	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'
 
-debug: ## Build a debug version
-	@mkdir -p $(mkfile_path)build
-	@go build main.go -o $(mkfile_path)open-go-knocking
+debug: clean-build ## Build a debug version
+	@mkdir -p $(build_path)
+	@go build -o $(build_path)open-go-knocking main.go
 	@echo "Debug release done"
 
 release: clean-build build-linux build-darwin build-windows ## Build the release version
 
 clean-build: ## Clean the build directory
-	@rm -fr @mkdir -p $(mkfile_path)build/*
+	@rm -fr $(build_path)/*
 
 build-linux: ## Build release version for GNU/Linux
-	@mkdir -p $(mkfile_path)build
-	@GOOS="linux" GOARCH="amd64" go build -ldflags="-X 'main.version=$(version)'" -o $(mkfile_path)open-go-knocking-$(version)-linux-amd64 main.go
-	@GOOS="linux" GOARCH="arm64" go build -ldflags="-X 'main.version=$(version)'" -o $(mkfile_path)open-go-knocking-$(version)-linux-arm64 main.go
-	@GOOS="linux" GOARCH="386" go build -ldflags="-X 'main.version=$(version)'" -o $(mkfile_path)open-go-knocking-$(version)-linux-386 main.go
+	@mkdir -p $(build_path)
+	@GOOS="linux" GOARCH="amd64" go build -ldflags="-X 'main.version=$(version)'" -o $(build_path)open-go-knocking-$(version)-linux-amd64 main.go
+	@GOOS="linux" GOARCH="arm64" go build -ldflags="-X 'main.version=$(version)'" -o $(build_path)open-go-knocking-$(version)-linux-arm64 main.go
+	@GOOS="linux" GOARCH="386" go build -ldflags="-X 'main.version=$(version)'" -o $(build_path)open-go-knocking-$(version)-linux-386 main.go
 
 build-darwin: ## Build release version for MacOS
-	@mkdir -p $(mkfile_path)build
-	@GOOS="darwin" GOARCH="amd64" go build -ldflags="-X 'main.version=$(version)'" -o $(mkfile_path)open-go-knocking-$(version)-darwin-amd64 main.go
-	@GOOS="darwin" GOARCH="arm64" go build -ldflags="-X 'main.version=v0.0.1'" -o $(mkfile_path)open-go-knocking-$(version)-darwin-arm64 main.go
+	@mkdir -p $(build_path)
+	@GOOS="darwin" GOARCH="amd64" go build -ldflags="-X 'main.version=$(version)'" -o $(build_path)open-go-knocking-$(version)-darwin-amd64 main.go
+	@GOOS="darwin" GOARCH="arm64" go build -ldflags="-X 'main.version=v0.0.1'" -o $(build_path)open-go-knocking-$(version)-darwin-arm64 main.go
 
 build-windows: ## Build release version for Windows
-	@mkdir -p $(mkfile_path)build
-	@GOOS="windows" GOARCH="amd64" go build -ldflags="-X 'main.version=$(version)'" -o $(mkfile_path)open-go-knocking-$(version)-windows-amd64.exe main.go
-	@GOOS="windows" GOARCH="386" go build -ldflags="-X 'main.version=$(version)'" -o $(mkfile_path)open-go-knocking-$(version)-windows-386.exe main.go
+	@mkdir -p $(build_path)
+	@GOOS="windows" GOARCH="amd64" go build -ldflags="-X 'main.version=$(version)'" -o $(build_path)open-go-knocking-$(version)-windows-amd64.exe main.go
+	@GOOS="windows" GOARCH="386" go build -ldflags="-X 'main.version=$(version)'" -o $(build_path)open-go-knocking-$(version)-windows-386.exe main.go

README.md

@@ -0,0 +1,64 @@
+# OpenGoKnocking
+
+Simple and cross-platform port knocking client written in GoLang.
+
+<p align="center">
+<img src="https://raw.githubusercontent.com/leblanc-simon/open-go-knocking/main/assets/open-go-knocking.png">
+</p>
+
+## Installation
+
+To install OpenGoKnocking in your $GOPATH:
+
+```bash
+git clone https://github.com/leblanc-simon/open-go-knocking.git
+cd open-go-knocking
+go install
+```
+
+alternatively, you can download binary from [releases](https://github.com/leblanc-simon/open-go-knocking/releases). 
+Binaries are availables for GNU/Linux, MacOS and Windows
+
+## Usage
+
+```bash
+# Knock to the server example.com at port 1337 (tcp), then 1338 (UDP) and finally 1339 (TCP)
+open-go-knocking example.com 1337:tcp 1338:udp 1339:tcp
+
+# If the majority of ports are TCP ports, you can use the following syntax (ports without protocol will be in TCP)
+open-go-knocking --tcp example.com 1337 1338:udp 1339
+
+# If the majority of ports are UDP ports, you can use the following syntax (ports without protocol will be in UDP)
+open-go-knocking --udp example.com 1337 1338:tcp 1339
+```
+
+## Options
+
+* `--tcp`: 
+* `--udp`: 
+* `--delay` (in ms): 
+* `--version`: Show the current version
+* `--help`: Show the help
+
+## Errors
+
+Possible exit codes :
+
+* 0: all is fine :)
+* 1: Not enough arguments (host and port are required)
+* 2: Host is not a valid hostname or IP (v4 or v6)
+* 3: Problems with ports or protocols (check if you use `--tcp` or `--udp` that the option is located before the host)
+
+## Author
+
+* Simon Leblanc <contact@leblanc-simon.eu>
+
+## License
+
+[WTFPL](http://www.wtfpl.net/)
+
+## Logo
+
+Original Logo from [Takuya Ueda](https://twitter.com/tenntenn), you can find source [in the repository](https://github.com/golang-samples/gopher-vector). Licensed under the Creative Commons 3.0 Attributions license.
+
+Modified by Simon Leblanc.

main.go

@@ -20,7 +20,7 @@ var (
 	versionFlag = flag.Bool("version", false, "Show version")
 	tcpFlag = flag.Bool("tcp", false, "Send all packets to TCP")
 	udpFlag = flag.Bool("udp", false, "Send all packets to UDP")
-	delayFlag = flag.Int("delay", 5, "Delay between each packet")
+	delayFlag = flag.Int("delay", 5, "Delay between each packet (in milliseconds)")
 
 	version = "develop"
 	appName = "OpenGoKnocking"
@@ -146,7 +146,7 @@ func main() {
 	}
 
 	if flag.CommandLine.NArg() < 2 {
-		exitWithError(1, "Arguments missing !", true)
+		exitWithError(ExitCodeBadArg, "Arguments missing !", true)
 	}
 
 	host := getHostAndVerify()