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Copy pathdownload.go
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411 lines (376 loc) · 13.4 KB
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// Copyright (c) 2021 Tulir Asokan
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
package whatsmeow
import (
"context"
"crypto/hmac"
"crypto/sha256"
"encoding/base64"
"encoding/json"
"errors"
"fmt"
"io"
"net"
"net/http"
"strings"
"time"
"go.mau.fi/util/retryafter"
"google.golang.org/protobuf/proto"
"google.golang.org/protobuf/reflect/protoreflect"
"go.mau.fi/whatsmeow/proto/waE2E"
"go.mau.fi/whatsmeow/proto/waHistorySync"
"go.mau.fi/whatsmeow/proto/waMediaTransport"
"go.mau.fi/whatsmeow/proto/waServerSync"
"go.mau.fi/whatsmeow/socket"
"go.mau.fi/whatsmeow/types"
"go.mau.fi/whatsmeow/util/cbcutil"
"go.mau.fi/whatsmeow/util/hkdfutil"
)
// MediaType represents a type of uploaded file on WhatsApp.
// The value is the key which is used as a part of generating the encryption keys.
type MediaType string
// The known media types
const (
MediaImage MediaType = "WhatsApp Image Keys"
MediaVideo MediaType = "WhatsApp Video Keys"
MediaAudio MediaType = "WhatsApp Audio Keys"
MediaDocument MediaType = "WhatsApp Document Keys"
MediaHistory MediaType = "WhatsApp History Keys"
MediaAppState MediaType = "WhatsApp App State Keys"
MediaStickerPack MediaType = "WhatsApp Sticker Pack Keys"
MediaLinkThumbnail MediaType = "WhatsApp Link Thumbnail Keys"
)
// DownloadableMessage represents a protobuf message that contains attachment info.
//
// All of the downloadable messages inside a Message struct implement this interface
// (ImageMessage, VideoMessage, AudioMessage, DocumentMessage, StickerMessage).
type DownloadableMessage interface {
GetDirectPath() string
GetMediaKey() []byte
GetFileSHA256() []byte
GetFileEncSHA256() []byte
}
type MediaTypeable interface {
GetMediaType() MediaType
}
// DownloadableThumbnail represents a protobuf message that contains a thumbnail attachment.
//
// This is primarily meant for link preview thumbnails in ExtendedTextMessage.
type DownloadableThumbnail interface {
proto.Message
GetThumbnailDirectPath() string
GetThumbnailSHA256() []byte
GetThumbnailEncSHA256() []byte
GetMediaKey() []byte
}
// All the message types that are intended to be downloadable
var (
_ DownloadableMessage = (*waE2E.ImageMessage)(nil)
_ DownloadableMessage = (*waE2E.AudioMessage)(nil)
_ DownloadableMessage = (*waE2E.VideoMessage)(nil)
_ DownloadableMessage = (*waE2E.DocumentMessage)(nil)
_ DownloadableMessage = (*waE2E.StickerMessage)(nil)
_ DownloadableMessage = (*waE2E.StickerPackMessage)(nil)
_ DownloadableMessage = (*waHistorySync.StickerMetadata)(nil)
_ DownloadableMessage = (*waE2E.HistorySyncNotification)(nil)
_ DownloadableMessage = (*waServerSync.ExternalBlobReference)(nil)
_ DownloadableThumbnail = (*waE2E.ExtendedTextMessage)(nil)
_ DownloadableMessage = (*types.StickerPackItem)(nil)
)
var classToMediaType = map[protoreflect.Name]MediaType{
"ImageMessage": MediaImage,
"AudioMessage": MediaAudio,
"VideoMessage": MediaVideo,
"DocumentMessage": MediaDocument,
"StickerMessage": MediaImage,
"StickerMetadata": MediaImage,
"StickerPackMessage": MediaStickerPack,
"HistorySyncNotification": MediaHistory,
"ExternalBlobReference": MediaAppState,
}
var classToThumbnailMediaType = map[protoreflect.Name]MediaType{
"ExtendedTextMessage": MediaLinkThumbnail,
}
var mediaTypeToMMSType = map[MediaType]string{
MediaImage: "image",
MediaAudio: "audio",
MediaVideo: "video",
MediaDocument: "document",
MediaHistory: "md-msg-hist",
MediaAppState: "md-app-state",
MediaStickerPack: "sticker-pack",
MediaLinkThumbnail: "thumbnail-link",
}
// DownloadAny loops through the downloadable parts of the given message and downloads the first non-nil item.
//
// Deprecated: it's recommended to find the specific message type you want to download manually and use the Download method instead.
func (cli *Client) DownloadAny(ctx context.Context, msg *waE2E.Message) (data []byte, err error) {
if msg == nil {
return nil, ErrNothingDownloadableFound
}
switch {
case msg.ImageMessage != nil:
return cli.Download(ctx, msg.ImageMessage)
case msg.VideoMessage != nil:
return cli.Download(ctx, msg.VideoMessage)
case msg.AudioMessage != nil:
return cli.Download(ctx, msg.AudioMessage)
case msg.DocumentMessage != nil:
return cli.Download(ctx, msg.DocumentMessage)
case msg.StickerMessage != nil:
return cli.Download(ctx, msg.StickerMessage)
default:
return nil, ErrNothingDownloadableFound
}
}
// DownloadThumbnail downloads a thumbnail from a message.
//
// This is primarily intended for downloading link preview thumbnails, which are in ExtendedTextMessage:
//
// var msg *waE2E.Message
// ...
// thumbnailImageBytes, err := cli.DownloadThumbnail(msg.GetExtendedTextMessage())
func (cli *Client) DownloadThumbnail(ctx context.Context, msg DownloadableThumbnail) ([]byte, error) {
mediaType, ok := classToThumbnailMediaType[msg.ProtoReflect().Descriptor().Name()]
if !ok {
return nil, fmt.Errorf("%w '%s'", ErrUnknownMediaType, string(msg.ProtoReflect().Descriptor().Name()))
} else if len(msg.GetThumbnailDirectPath()) > 0 {
return cli.DownloadMediaWithPath(
ctx, msg.GetThumbnailDirectPath(), msg.GetThumbnailEncSHA256(), msg.GetThumbnailSHA256(), msg.GetMediaKey(),
mediaType, mediaTypeToMMSType[mediaType], false,
)
} else {
return nil, ErrNoURLPresent
}
}
// GetMediaType returns the MediaType value corresponding to the given protobuf message.
func GetMediaType(msg DownloadableMessage) MediaType {
switch typedMsg := msg.(type) {
case *types.StickerPackItem:
return MediaImage
case proto.Message:
return classToMediaType[typedMsg.ProtoReflect().Descriptor().Name()]
case MediaTypeable:
return typedMsg.GetMediaType()
default:
return ""
}
}
func (cli *Client) FetchStickerPack(ctx context.Context, packID string) (*types.StickerPack, error) {
url := fmt.Sprintf("https://static.whatsapp.net/sticker?lottie=1&cat=sticker_pack_data&id=%s&lg=en", packID)
resp, err := cli.doMediaDownloadRequest(ctx, url)
if err != nil {
return nil, err
}
var packs []types.StickerPack
err = json.NewDecoder(resp.Body).Decode(&packs)
_ = resp.Body.Close()
if err != nil {
return nil, fmt.Errorf("failed to decode response: %w", err)
} else if len(packs) == 0 {
return nil, fmt.Errorf("no sticker pack found in response")
}
return &packs[0], nil
}
// Download downloads the attachment from the given protobuf message.
//
// The attachment is a specific part of a Message protobuf struct, not the message itself, e.g.
//
// var msg *waE2E.Message
// ...
// imageData, err := cli.Download(msg.GetImageMessage())
//
// You can also use DownloadAny to download the first non-nil sub-message.
func (cli *Client) Download(ctx context.Context, msg DownloadableMessage) ([]byte, error) {
if cli == nil {
return nil, ErrClientIsNil
}
mediaType := GetMediaType(msg)
if mediaType == "" {
return nil, fmt.Errorf("%w %T", ErrUnknownMediaType, msg)
}
if len(msg.GetDirectPath()) == 0 {
return nil, ErrNoURLPresent
}
return cli.DownloadMediaWithPath(
ctx, msg.GetDirectPath(), msg.GetFileEncSHA256(), msg.GetFileSHA256(), msg.GetMediaKey(),
mediaType, mediaTypeToMMSType[mediaType], false,
)
}
func (cli *Client) DownloadFB(
ctx context.Context,
transport *waMediaTransport.WAMediaTransport_Integral,
mediaType MediaType,
) ([]byte, error) {
return cli.DownloadMediaWithPath(
ctx, transport.GetDirectPath(), transport.GetFileEncSHA256(), transport.GetFileSHA256(), transport.GetMediaKey(),
mediaType, mediaTypeToMMSType[mediaType], false,
)
}
func (cli *Client) DownloadMediaWithOnlyPath(ctx context.Context, directPath string) ([]byte, error) {
return cli.DownloadMediaWithPath(ctx, directPath, nil, nil, nil, "", "", true)
}
// DownloadMediaWithPath downloads an attachment by manually specifying the path and encryption details.
func (cli *Client) DownloadMediaWithPath(
ctx context.Context,
directPath string,
encFileHash, fileHash, mediaKey []byte,
mediaType MediaType,
mmsType string,
allowNoHash bool,
) (data []byte, err error) {
if !allowNoHash && fileHash == nil {
fileHash = make([]byte, 32)
}
if !strings.HasPrefix(directPath, "/") {
return nil, fmt.Errorf("media download path does not start with slash: %s", directPath)
}
var mediaConn *MediaConn
mediaConn, err = cli.refreshMediaConn(ctx, false)
if err != nil {
return nil, fmt.Errorf("failed to refresh media connections: %w", err)
}
if len(mmsType) == 0 {
mmsType = mediaTypeToMMSType[mediaType]
}
for i, host := range mediaConn.Hosts {
// TODO omit hash for unencrypted media?
mediaURL := fmt.Sprintf("https://%s%s&hash=%s&mms-type=%s&__wa-mms=", host.Hostname, directPath, base64.URLEncoding.EncodeToString(encFileHash), mmsType)
data, err = cli.downloadAndDecrypt(ctx, mediaURL, mediaKey, mediaType, encFileHash, fileHash)
if err == nil ||
errors.Is(err, ErrInvalidMediaSHA256) ||
errors.Is(err, ErrMediaDownloadFailedWith403) ||
errors.Is(err, ErrMediaDownloadFailedWith404) ||
errors.Is(err, ErrMediaDownloadFailedWith410) ||
errors.Is(err, context.Canceled) {
return
} else if i >= len(mediaConn.Hosts)-1 {
return nil, fmt.Errorf("failed to download media from last host: %w", err)
}
cli.Log.Warnf("Failed to download media: %s, trying with next host...", err)
}
return
}
func (cli *Client) downloadAndDecrypt(
ctx context.Context,
url string,
mediaKey []byte,
appInfo MediaType,
fileEncSHA256,
fileSHA256 []byte,
) (data []byte, err error) {
iv, cipherKey, macKey, _ := getMediaKeys(mediaKey, appInfo)
var ciphertext, mac []byte
if ciphertext, mac, err = cli.downloadPossiblyEncryptedMediaWithRetries(ctx, url, fileEncSHA256); err != nil {
} else if mediaKey == nil && fileEncSHA256 == nil && mac == nil {
// Unencrypted media, just check the hash and return
data = ciphertext
if fileSHA256 != nil && (len(fileSHA256) != 32 || sha256.Sum256(data) != *(*[32]byte)(fileSHA256)) {
err = ErrInvalidUnencryptedMediaSHA256
}
} else if err = validateMedia(iv, ciphertext, macKey, mac); err != nil {
} else if data, err = cbcutil.Decrypt(cipherKey, iv, ciphertext); err != nil {
err = fmt.Errorf("failed to decrypt file: %w", err)
} else if len(fileSHA256) != 32 || sha256.Sum256(data) != *(*[32]byte)(fileSHA256) {
err = ErrInvalidMediaSHA256
}
return
}
func getMediaKeys(mediaKey []byte, appInfo MediaType) (iv, cipherKey, macKey, refKey []byte) {
mediaKeyExpanded := hkdfutil.SHA256(mediaKey, nil, []byte(appInfo), 112)
return mediaKeyExpanded[:16], mediaKeyExpanded[16:48], mediaKeyExpanded[48:80], mediaKeyExpanded[80:]
}
func shouldRetryMediaDownload(err error) bool {
if errors.Is(err, context.Canceled) {
return false
}
var netErr net.Error
var httpErr DownloadHTTPError
return errors.As(err, &netErr) ||
strings.HasPrefix(err.Error(), "stream error:") || // hacky check for http2 errors
(errors.As(err, &httpErr) && retryafter.Should(httpErr.StatusCode, true))
}
func (cli *Client) downloadPossiblyEncryptedMediaWithRetries(ctx context.Context, url string, checksum []byte) (file, mac []byte, err error) {
for retryNum := 0; retryNum < 5; retryNum++ {
if checksum == nil {
file, err = cli.downloadMedia(ctx, url)
} else {
file, mac, err = cli.downloadEncryptedMedia(ctx, url, checksum)
}
if err == nil || !shouldRetryMediaDownload(err) {
return
}
retryDuration := time.Duration(retryNum+1) * time.Second
var httpErr DownloadHTTPError
if errors.As(err, &httpErr) {
retryDuration = retryafter.Parse(httpErr.Response.Header.Get("Retry-After"), retryDuration)
}
cli.Log.Warnf("Failed to download media due to network error: %v, retrying in %s...", err, retryDuration)
select {
case <-ctx.Done():
return nil, nil, ctx.Err()
case <-time.After(retryDuration):
}
}
return
}
func (cli *Client) doMediaDownloadRequest(ctx context.Context, url string) (*http.Response, error) {
req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
if err != nil {
return nil, fmt.Errorf("failed to prepare request: %w", err)
}
req.Header.Set("Origin", socket.Origin)
req.Header.Set("Referer", socket.Origin+"/")
if cli.MessengerConfig != nil {
req.Header.Set("User-Agent", cli.MessengerConfig.UserAgent)
}
// TODO user agent for whatsapp downloads?
resp, err := cli.mediaHTTP.Do(req)
if err != nil {
return nil, err
}
if resp.StatusCode != http.StatusOK {
_ = resp.Body.Close()
return nil, DownloadHTTPError{Response: resp}
}
return resp, nil
}
func (cli *Client) downloadMedia(ctx context.Context, url string) ([]byte, error) {
resp, err := cli.doMediaDownloadRequest(ctx, url)
if err != nil {
return nil, err
}
data, err := io.ReadAll(resp.Body)
_ = resp.Body.Close()
return data, err
}
const mediaHMACLength = 10
func (cli *Client) downloadEncryptedMedia(ctx context.Context, url string, checksum []byte) (file, mac []byte, err error) {
if len(checksum) != 32 {
return nil, nil, fmt.Errorf("invalid checksum length: expected 32, got %d", len(checksum))
}
data, err := cli.downloadMedia(ctx, url)
if err != nil {
return
} else if len(data) <= mediaHMACLength {
err = ErrTooShortFile
return
}
file, mac = data[:len(data)-mediaHMACLength], data[len(data)-mediaHMACLength:]
if sha256.Sum256(data) != *(*[32]byte)(checksum) {
err = ErrInvalidMediaEncSHA256
}
return
}
func validateMedia(iv, file, macKey, mac []byte) error {
h := hmac.New(sha256.New, macKey)
h.Write(iv)
h.Write(file)
if !hmac.Equal(h.Sum(nil)[:mediaHMACLength], mac) {
return ErrInvalidMediaHMAC
}
return nil
}