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main.go
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main.go
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package main
import (
"archive/zip"
"bytes"
"flag"
"fmt"
"io/ioutil"
"log"
"math/rand"
"os"
"os/exec"
"path/filepath"
"time"
"github.com/google/uuid"
)
func main() {
demo := flag.Bool("demo", false, "")
in := flag.String("in", "./in", "")
out := flag.String("out", "./out/results.zip", "")
flag.Parse()
participants := readNames(*in)
pairs := findPairs(randomize(participants))
if *demo {
print(pairs)
return
}
os.MkdirAll(filepath.Dir(*out), os.ModePerm)
writeResults(*in, *out, pairs)
}
func print(pairs map[string]string) {
for k, v := range pairs {
fmt.Printf("%s -> %s\n", k, v)
}
}
func findPairs(participants []string) map[string]string {
pairs := map[string]string{}
takers := map[string]bool{}
for _, giver := range participants {
inner:
for _, taker := range participants {
_, alreadyGave := pairs[giver]
givingToTaker := pairs[taker] == giver
alreadyTook := takers[taker]
if !alreadyGave && !alreadyTook && !givingToTaker && giver != taker {
takers[taker] = true
pairs[giver] = taker
break inner
}
}
}
return pairs
}
func randomize(participants []string) []string {
s := rand.NewSource(time.Now().UTC().UnixNano())
r := rand.New(s)
count := len(participants)
permutation := r.Perm(count)
randomized := make([]string, count)
for i, p := range permutation {
randomized[i] = participants[p]
}
return randomized
}
func readNames(dir string) []string {
var names = make([]string, 0)
files, err := ioutil.ReadDir(dir)
if err != nil {
log.Fatal(err)
}
for _, file := range files {
names = append(names, file.Name())
}
return names
}
func encrypt(plain []byte, keyPath string) []byte {
sshKeygen := exec.Command("ssh-keygen", "-f", keyPath, "-e", "-m", "PKCS8")
var stdout bytes.Buffer
sshKeygen.Stdout = &stdout
err := sshKeygen.Run()
if err != nil {
log.Fatalf("Error running ssh-keygen: %v\n", err)
}
pem := stdout.Bytes()
stdout.Reset()
tempFilename := uuid.New().String()
err = ioutil.WriteFile(tempFilename, pem, 0644)
if err != nil {
log.Fatal(err)
}
defer os.Remove(tempFilename)
openssl := exec.Command("openssl", "rsautl", "-encrypt", "-pubin", "-inkey", tempFilename, "-ssl")
openssl.Stdin = bytes.NewBuffer(plain)
openssl.Stdout = &stdout
err = openssl.Run()
if err != nil {
log.Fatal(err)
}
return stdout.Bytes()
}
var readme = "# How to Read the Result\n\n" +
"In the directory containing this README:\n\n" +
"```bash\n" +
"chmod +x decrypt\n" +
"cat <YOUR NAME> | ./decrypt\n" +
"```\n\n" +
"By default the private key located in ~/.ssh/id_rsa is used.\n"
var decryptScript = "#!/bin/bash\n\n" +
"cat | openssl rsautl -decrypt -inkey ~/.ssh/id_rsa\n"
func writeToArchive(w *zip.Writer, name string, content []byte) {
f, err := w.Create(name)
if err != nil {
log.Fatal(err)
}
_, err = f.Write(content)
if err != nil {
log.Fatal(err)
}
}
func writeResults(sourceDir string, targetPath string, pairs map[string]string) {
buf := new(bytes.Buffer)
w := zip.NewWriter(buf)
writeToArchive(w, "README.md", []byte(readme))
writeToArchive(w, "decrypt", []byte(decryptScript))
for k, v := range pairs {
sourcePath := fmt.Sprintf("%s/%s", sourceDir, k)
encrypted := encrypt([]byte(v), sourcePath)
f, err := w.Create(k)
if err != nil {
log.Fatal(err)
}
_, err = f.Write(encrypted)
if err != nil {
log.Fatal(err)
}
}
err := w.Close()
if err != nil {
log.Fatal(err)
}
err = ioutil.WriteFile(targetPath, buf.Bytes(), 0644)
if err != nil {
log.Fatal(err)
}
}