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FileDownload.go
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FileDownload.go
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package libdatamanager
import (
"encoding/hex"
"errors"
"hash/crc32"
"io"
"net/http"
"os"
"path/filepath"
"strconv"
gzip "github.com/klauspost/pgzip"
)
var (
// ErrChecksumNotMatch error if the checksum of the downloaded
// file doesn't match with the checksum of the remote file
ErrChecksumNotMatch = errors.New("generated checksum not match")
// ErrCipherNotSupported if cipher is not supported
ErrCipherNotSupported = errors.New("cipher not supported")
// ErrFileEncrypted error if no key was given and nodecrypt is false
ErrFileEncrypted = errors.New("file is encrypted but no key was given")
)
// FileDownloadRequest request for downloading a file
type FileDownloadRequest struct {
LibDM
ID uint
Name string
Namespace string
Decrypt bool
Key []byte
Buffersize int
ignoreChecksum bool
CancelDownload chan bool
WriterProxy WriterProxy
ReaderProxy ReaderProxy
}
// NewFileRequest create a new filerequest
func (libdm LibDM) NewFileRequest(id uint, name, namespace string) *FileDownloadRequest {
return &FileDownloadRequest{
LibDM: libdm,
Buffersize: DefaultBuffersize,
Decrypt: true,
Name: name,
Namespace: namespace,
ID: id,
}
}
// NewFileRequestByName create a new filerequest by name
func (libdm LibDM) NewFileRequestByName(name, namespace string) *FileDownloadRequest {
return &FileDownloadRequest{
LibDM: libdm,
Decrypt: true,
Name: name,
Namespace: namespace,
Buffersize: DefaultBuffersize,
}
}
// NewFileRequestByID create a new filerequest by file id
func (libdm LibDM) NewFileRequestByID(fileID uint) *FileDownloadRequest {
return &FileDownloadRequest{
LibDM: libdm,
Decrypt: true,
ID: fileID,
Buffersize: DefaultBuffersize,
}
}
// GetWriterProxy returns proxywriter of request
func (fileRequest *FileDownloadRequest) GetWriterProxy() WriterProxy {
if fileRequest.WriterProxy == nil {
return NoProxyWriter
}
return fileRequest.WriterProxy
}
// GetReaderProxy of request
func (fileRequest *FileDownloadRequest) GetReaderProxy() ReaderProxy {
if fileRequest.ReaderProxy == nil {
return NoProxyReader
}
return fileRequest.ReaderProxy
}
// GetBuffersize gets the buffersize
func (fileRequest *FileDownloadRequest) GetBuffersize() int {
if fileRequest.Buffersize <= 0 {
return DefaultBuffersize
}
return fileRequest.Buffersize
}
// IgnoreChecksum ignores the checksum
func (fileRequest *FileDownloadRequest) IgnoreChecksum() *FileDownloadRequest {
fileRequest.ignoreChecksum = true
return fileRequest
}
// NoDecrypt don't decrypt file while downloading
func (fileRequest *FileDownloadRequest) NoDecrypt() *FileDownloadRequest {
fileRequest.Decrypt = false
return fileRequest
}
// DecryptWith sets key to decrypt file with. If key is nil, no decryption will be performed
func (fileRequest *FileDownloadRequest) DecryptWith(key []byte) *FileDownloadRequest {
if key == nil {
return fileRequest.NoDecrypt()
}
fileRequest.Key = key
return fileRequest
}
// Do requests a filedownload and returns the response
// The response body must be closed
func (fileRequest *FileDownloadRequest) Do() (*FileDownloadResponse, error) {
resp, err := fileRequest.NewRequest(EPFileGet, &FileRequest{
Name: fileRequest.Name,
FileID: fileRequest.ID,
Attributes: FileAttributes{
Namespace: fileRequest.Namespace,
},
}).WithAuthFromConfig().DoHTTPRequest()
// Check for error
if err != nil {
return nil, &ResponseErr{
Err: err,
}
}
// Check response headers
if resp.Header.Get(HeaderStatus) == strconv.Itoa(int(ResponseError)) {
return nil, &ResponseErr{
Response: &RestRequestResponse{
HTTPCode: resp.StatusCode,
Headers: &resp.Header,
Message: resp.Header.Get(HeaderStatusMessage),
Status: ResponseError,
},
}
}
// Get filename from headers
serverFileName := resp.Header.Get(HeaderFileName)
// Get file checksum from headers
checksum := resp.Header.Get(HeaderChecksum)
// Get encryption header
encryption := resp.Header.Get(HeaderEncryption)
// Get filetype
fileType := resp.Header.Get(HeaderFileType)
// Get size header
size := GetFilesizeFromDownloadRequest(resp)
// Get size header
var id uint
iid, err := strconv.ParseUint(resp.Header.Get(HeaderFileID), 10, 32)
if err == nil {
id = uint(iid)
}
// Check headers
if len(serverFileName) == 0 {
return nil, &ResponseErr{
Err: ErrResponseFilenameInvalid,
}
}
// Return file response
return &FileDownloadResponse{
Response: resp,
ServerChecksum: checksum,
Encryption: encryption,
FileType: fileType,
ServerFileName: serverFileName,
Size: size,
DownloadRequest: fileRequest,
FileID: id,
}, nil
}
// WriteToFile saves a file to the given localFilePath containing the body of the given response
func (fileresponse *FileDownloadResponse) WriteToFile(localFilePath string, fmode os.FileMode, cancelChan chan bool) error {
// Create loal file
f, err := os.OpenFile(localFilePath, os.O_CREATE|os.O_TRUNC|os.O_RDWR, fmode)
defer f.Close()
if err != nil {
return err
}
// Save body to file using given proxy
err = fileresponse.SaveTo(f, cancelChan)
if err != nil {
return err
}
// Verify checksum if not ignored
if !fileresponse.VerifyChecksum() && !fileresponse.DownloadRequest.ignoreChecksum {
return ErrChecksumNotMatch
}
// Save to file using a proxy
return nil
}
// DownloadToFile downloads and saves a file to the given localFilePath. If the file exists, it will be overwritten
func (fileRequest *FileDownloadRequest) DownloadToFile(localFilePath string, fmode os.FileMode, appendFilename ...bool) (*FileDownloadResponse, error) {
resp, err := fileRequest.Do()
if err != nil {
return nil, err
}
defer resp.Response.Body.Close()
// Append remote filename if desired
if len(appendFilename) > 0 && appendFilename[0] {
localFilePath = filepath.Join(localFilePath, resp.ServerFileName)
}
// Create loal file
f, err := os.OpenFile(localFilePath, os.O_CREATE|os.O_TRUNC|os.O_RDWR, fmode)
defer f.Close()
if err != nil {
return nil, err
}
// Write to file
err = resp.SaveTo(f, fileRequest.CancelDownload)
if err != nil {
return nil, err
}
// Verify checksum if not disabled
if !fileRequest.ignoreChecksum && !resp.VerifyChecksum() {
return resp, ErrChecksumNotMatch
}
return resp, nil
}
// FileDownloadResponse response for downloading a file
type FileDownloadResponse struct {
Response *http.Response
ServerFileName string
LocalChecksum string
ServerChecksum string
Size int64
Encryption string
FileID uint
Extract bool
FileType string
DownloadRequest *FileDownloadRequest
}
// VerifyChecksum Return if checksums are equal and not empty
func (fileresponse *FileDownloadResponse) VerifyChecksum() bool {
return fileresponse.ServerChecksum == fileresponse.LocalChecksum && len(fileresponse.LocalChecksum) > 0
}
// SaveTo download a file and write it to the writer while
func (fileresponse *FileDownloadResponse) SaveTo(w io.Writer, cancelChan chan bool) error {
defer fileresponse.Response.Body.Close()
var err error
buff := make([]byte, fileresponse.DownloadRequest.GetBuffersize())
hash := crc32.NewIEEE()
reader := io.TeeReader(fileresponse.DownloadRequest.GetReaderProxy()(fileresponse.Response.Body), hash)
var gz *gzip.Reader
// TODO let the server decide whether to
// extract. Otherwise compressed files
// can't be decrypted correctly!!
if fileresponse.Extract {
gz, err = gzip.NewReader(reader)
if err != nil {
return err
}
reader = gz
}
w = fileresponse.DownloadRequest.GetWriterProxy()(w)
// If decryption is requested and required
if fileresponse.DownloadRequest.Decrypt && len(fileresponse.Encryption) > 0 {
// Throw error if no key was given
if len(fileresponse.DownloadRequest.Key) == 0 {
return ErrFileEncrypted
}
switch fileresponse.Encryption {
case EncryptionCiphers[0]:
// Decrypt aes
err = DecryptAES(reader, &w, nil, fileresponse.DownloadRequest.Key, buff, fileresponse.DownloadRequest.CancelDownload)
case EncryptionCiphers[1]:
// Decrypt aes
err = DecryptAGE(reader, w, nil, fileresponse.DownloadRequest.Key, buff, fileresponse.DownloadRequest.CancelDownload)
default:
return ErrCipherNotSupported
}
} else {
// Use multiwriter to write to hash and file
// at the same time
err = cancelledCopy(w, reader, buff, cancelChan)
}
// Close gzipWriter
if fileresponse.Extract {
gz.Close()
}
if err != nil {
return err
}
// Set local calculated checksum
fileresponse.LocalChecksum = hex.EncodeToString(hash.Sum(nil))
return nil
}
func cancelledCopy(writer io.Writer, f io.Reader, buf []byte, cancelChan chan bool) error {
for {
// Exit on cancel
select {
case _ = <-cancelChan:
return ErrCancelled
default:
}
n, err := f.Read(buf)
if n > 0 {
_, err := writer.Write(buf[:n])
if err != nil {
return err
}
}
if err == io.EOF {
break
} else if err != nil {
return err
}
}
return nil
}
// GetFilesizeFromDownloadRequest returns the filesize from a
// file from the response headers
func GetFilesizeFromDownloadRequest(resp *http.Response) int64 {
// Get the header
sizeHeader := resp.Header.Get(HeaderContentLength)
// Validate it
if len(sizeHeader) > 0 {
// Parse it
s, err := strconv.ParseInt(sizeHeader, 10, 64)
if err == nil {
return s
}
}
return 0
}