package common import ( "bytes" "crypto/md5" "crypto/sha1" "crypto/sha256" "crypto/sha512" "encoding/hex" "errors" "fmt" "hash" "io" "log" "net/http" "net/url" "os" "runtime" ) // DownloadConfig is the configuration given to instantiate a new // download instance. Once a configuration is used to instantiate // a download client, it must not be modified. type DownloadConfig struct { // The source URL in the form of a string. Url string // This is the path to download the file to. TargetPath string // DownloaderMap maps a schema to a Download. DownloaderMap map[string]Downloader // If true, this will copy even a local file to the target // location. If false, then it will "download" the file by just // returning the local path to the file. CopyFile bool // The hashing implementation to use to checksum the downloaded file. Hash hash.Hash // The checksum for the downloaded file. The hash implementation configuration // for the downloader will be used to verify with this checksum after // it is downloaded. Checksum []byte // What to use for the user agent for HTTP requests. If set to "", use the // default user agent provided by Go. UserAgent string } // A DownloadClient helps download, verify checksums, etc. type DownloadClient struct { config *DownloadConfig downloader Downloader } // HashForType returns the Hash implementation for the given string // type, or nil if the type is not supported. func HashForType(t string) hash.Hash { switch t { case "md5": return md5.New() case "sha1": return sha1.New() case "sha256": return sha256.New() case "sha512": return sha512.New() default: return nil } } // NewDownloadClient returns a new DownloadClient for the given // configuration. func NewDownloadClient(c *DownloadConfig) *DownloadClient { if c.DownloaderMap == nil { c.DownloaderMap = map[string]Downloader{ "http": &HTTPDownloader{userAgent: c.UserAgent}, "https": &HTTPDownloader{userAgent: c.UserAgent}, } } return &DownloadClient{config: c} } // A downloader is responsible for actually taking a remote URL and // downloading it. type Downloader interface { Cancel() Download(*os.File, *url.URL) error Progress() uint Total() uint } func (d *DownloadClient) Cancel() { // TODO(mitchellh): Implement } func (d *DownloadClient) Get() (string, error) { // If we already have the file and it matches, then just return the target path. if verify, _ := d.VerifyChecksum(d.config.TargetPath); verify { log.Println("[DEBUG] Initial checksum matched, no download needed.") return d.config.TargetPath, nil } url, err := url.Parse(d.config.Url) if err != nil { return "", err } log.Printf("Parsed URL: %#v", url) // Files when we don't copy the file are special cased. var f *os.File var finalPath string sourcePath := "" if url.Scheme == "file" && !d.config.CopyFile { // This is a special case where we use a source file that already exists // locally and we don't make a copy. Normally we would copy or download. finalPath = url.Path log.Printf("[DEBUG] Using local file: %s", finalPath) // Remove forward slash on absolute Windows file URLs before processing if runtime.GOOS == "windows" && len(finalPath) > 0 && finalPath[0] == '/' { finalPath = finalPath[1:len(finalPath)] } // Keep track of the source so we can make sure not to delete this later sourcePath = finalPath } else { finalPath = d.config.TargetPath var ok bool d.downloader, ok = d.config.DownloaderMap[url.Scheme] if !ok { return "", fmt.Errorf("No downloader for scheme: %s", url.Scheme) } // Otherwise, download using the downloader. f, err = os.OpenFile(finalPath, os.O_RDWR|os.O_CREATE, os.FileMode(0666)) if err != nil { return "", err } log.Printf("[DEBUG] Downloading: %s", url.String()) err = d.downloader.Download(f, url) f.Close() if err != nil { return "", err } } if d.config.Hash != nil { var verify bool verify, err = d.VerifyChecksum(finalPath) if err == nil && !verify { // Only delete the file if we made a copy or downloaded it if sourcePath != finalPath { os.Remove(finalPath) } err = fmt.Errorf( "checksums didn't match expected: %s", hex.EncodeToString(d.config.Checksum)) } } return finalPath, err } // PercentProgress returns the download progress as a percentage. func (d *DownloadClient) PercentProgress() int { if d.downloader == nil { return -1 } return int((float64(d.downloader.Progress()) / float64(d.downloader.Total())) * 100) } // VerifyChecksum tests that the path matches the checksum for the // download. func (d *DownloadClient) VerifyChecksum(path string) (bool, error) { if d.config.Checksum == nil || d.config.Hash == nil { return false, errors.New("Checksum or Hash isn't set on download.") } f, err := os.Open(path) if err != nil { return false, err } defer f.Close() log.Printf("Verifying checksum of %s", path) d.config.Hash.Reset() io.Copy(d.config.Hash, f) return bytes.Compare(d.config.Hash.Sum(nil), d.config.Checksum) == 0, nil } // HTTPDownloader is an implementation of Downloader that downloads // files over HTTP. type HTTPDownloader struct { progress uint total uint userAgent string } func (*HTTPDownloader) Cancel() { // TODO(mitchellh): Implement } func (d *HTTPDownloader) Download(dst *os.File, src *url.URL) error { log.Printf("Starting download: %s", src.String()) // Seek to the beginning by default if _, err := dst.Seek(0, 0); err != nil { return err } // Reset our progress d.progress = 0 // Make the request. We first make a HEAD request so we can check // if the server supports range queries. If the server/URL doesn't // support HEAD requests, we just fall back to GET. req, err := http.NewRequest("HEAD", src.String(), nil) if err != nil { return err } if d.userAgent != "" { req.Header.Set("User-Agent", d.userAgent) } httpClient := &http.Client{ Transport: &http.Transport{ Proxy: http.ProxyFromEnvironment, }, } resp, err := httpClient.Do(req) if err == nil && (resp.StatusCode >= 200 && resp.StatusCode < 300) { // If the HEAD request succeeded, then attempt to set the range // query if we can. if resp.Header.Get("Accept-Ranges") == "bytes" { if fi, err := dst.Stat(); err == nil { if _, err = dst.Seek(0, os.SEEK_END); err == nil { req.Header.Set("Range", fmt.Sprintf("bytes=%d-", fi.Size())) d.progress = uint(fi.Size()) } } } } // Set the request to GET now, and redo the query to download req.Method = "GET" resp, err = httpClient.Do(req) if err != nil { return err } d.total = d.progress + uint(resp.ContentLength) var buffer [4096]byte for { n, err := resp.Body.Read(buffer[:]) if err != nil && err != io.EOF { return err } d.progress += uint(n) if _, werr := dst.Write(buffer[:n]); werr != nil { return werr } if err == io.EOF { break } } return nil } func (d *HTTPDownloader) Progress() uint { return d.progress } func (d *HTTPDownloader) Total() uint { return d.total }