utils.go

package main

import (
	"bytes"
	"io/ioutil"
	"log"
	"math/rand"
	"net"
	"net/http"
	"strings"
	"time"
)

func getPublicKeys(user string) []string {
	var url bytes.Buffer
	url.WriteString("https://github.com/")
	url.WriteString(user)
	url.WriteString(".keys")

	log.Printf("Getting public keys for %s", user)
	response, err := http.Get(url.String())
	if err != nil {
		log.Fatal(err)
	} else {
		defer response.Body.Close()
		body, _ := ioutil.ReadAll(response.Body)
		return strings.Split(string(body), "\n")
	}
	return nil
}

func getFreePort() (int, error) {
	addr, err := net.ResolveTCPAddr("tcp", "localhost:0")
	if err != nil {
		return 0, err
	}

	l, err := net.ListenTCP("tcp", addr)
	if err != nil {
		return 0, err
	}
	defer l.Close()
	return l.Addr().(*net.TCPAddr).Port, nil
}

func contains(arr []string, str string) bool {
	for _, a := range arr {
		if a == str {
			return true
		}
	}
	return false
}

// From: https://stackoverflow.com/questions/22892120/how-to-generate-a-random-string-of-a-fixed-length-in-golang?answertab=votes#tab-top
const letterBytes = "abcdefghijklmnopqrstuvwxyz"
const (
	letterIdxBits = 6                    // 6 bits to represent a letter index
	letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
	letterIdxMax  = 63 / letterIdxBits   // # of letter indices fitting in 63 bits
)

var src = rand.NewSource(time.Now().UnixNano())

func randStringBytesMaskImprSrc(n int) string {
	b := make([]byte, n)
	// A src.Int63() generates 63 random bits, enough for letterIdxMax characters!
	for i, cache, remain := n-1, src.Int63(), letterIdxMax; i >= 0; {
		if remain == 0 {
			cache, remain = src.Int63(), letterIdxMax
		}
		if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
			b[i] = letterBytes[idx]
			i--
		}
		cache >>= letterIdxBits
		remain--
	}

	return string(b)
}