KeyGenGo

kgen.go

// https://play.golang.org/p/zu7mtEWy7e

package main

import (
    "flag"
    "fmt"
    "log"
    "math/rand"
    "os"
    "time"
)

func init() {
    rand.Seed(time.Now().UnixNano())
    flag.Usage = func() {
    fmt.Printf("Usage: kgen [options] param\n")
        flag.PrintDefaults()
    }
}

const alpha = "abcdefghijklmnopqrstuvwxyz"
const alphaCap = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
const numeric = "0123456789"

var max = flag.Uint("max", 255, "Max size")
var format = flag.String("type", "all", "Type of key (all,upper,lower,num)")
var size = flag.Uint("len", 12, "Length of key")

func Random(c chan string) {
    chars := getChars(*format)
    for {
        c <- string(chars[rand.Intn(len(chars))])
    }
}

func getChars(key string) string {
    m := map[string]string{
        "all":   numeric + alpha + alphaCap,
        "upper": alphaCap,
        "lower": alpha,
        "num":   numeric,
    }
    if s, ok := m[key]; ok {
        return s
    }
    return m["all"]
}

func printer(size uint, c chan string) {
    var i uint
    for i = 0; i < size; i++ {
        fmt.Printf("%s", <-c)
    }
    fmt.Println("")
}

func keygen(length uint, max uint) {
    ch := make(chan string)
    go Random(ch)

    if length > max {
        log.Printf("The size is more than %d", max)
        os.Exit(1)
    }
    printer(length, ch)
}

func main() {
    flag.Parse()
    keygen(*size, *max)
}