kubenetworks/kubevpn

package main

import (
    "crypto/sha256"
    "encoding/hex"
    "fmt"
    "io"
    "net/http"
    "os"
    "path/filepath"
    "time"

    log "github.com/sirupsen/logrus"
)

const retries = 4

// DownloadFileWithName downloads a file with name
func DownloadFileWithName(uri, name string) (string, error) {
    resp, err := getWithRetry(uri)
    if err != nil {
        return "", err
    }
    defer resp.Body.Close()

    if resp.StatusCode != http.StatusOK {
        return "", fmt.Errorf("downloading file %s failed. status code: %d, expected: %d", uri, resp.StatusCode, http.StatusOK)
    }

    dir, err := os.MkdirTemp("", "")
    if err != nil {
        return "", err
    }

    file := filepath.Join(dir, name)
    out, err := os.Create(file)
    if err != nil {
        return "", err
    }
    defer out.Close()

    _, err = io.Copy(out, resp.Body)
    if err != nil {
        return "", fmt.Errorf("failed to save file %s. error: %v", file, err)
    }

    log.Infof("Downloaded file %s", file)
    return file, nil
}

func downloadFile(uri string) (string, error) {
    return DownloadFileWithName(uri, fmt.Sprintf("%d", time.Now().Unix()))
}

func GetSha256ForAsset(uri string) (string, error) {
    file, err := downloadFile(uri)
    if err != nil {
        return "", err
    }

    defer os.Remove(file)
    sha256, err := getSha256(file)
    if err != nil {
        return "", err
    }

    return sha256, nil
}

func getSha256(filename string) (string, error) {
    f, err := os.Open(filename)
    if err != nil {
        return "", err
    }
    defer f.Close()

    h := sha256.New()
    if _, err := io.Copy(h, f); err != nil {
        return "", err
    }

    return hex.EncodeToString(h.Sum(nil)), nil
}