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// Copyright (c) 2022 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 (
"crypto/rand"
"fmt"
"google.golang.org/protobuf/proto"
waBinary "go.mau.fi/whatsmeow/binary"
waProto "go.mau.fi/whatsmeow/binary/proto"
"go.mau.fi/whatsmeow/types"
"go.mau.fi/whatsmeow/types/events"
"go.mau.fi/whatsmeow/util/gcmutil"
"go.mau.fi/whatsmeow/util/hkdfutil"
)
func getMediaRetryKey(mediaKey []byte) (cipherKey []byte) {
return hkdfutil.SHA256(mediaKey, nil, []byte("WhatsApp Media Retry Notification"), 32)
}
func encryptMediaRetryReceipt(messageID types.MessageID, mediaKey []byte) (ciphertext, iv []byte, err error) {
receipt := &waProto.ServerErrorReceipt{
StanzaId: proto.String(messageID),
}
var plaintext []byte
plaintext, err = proto.Marshal(receipt)
if err != nil {
err = fmt.Errorf("failed to marshal payload: %w", err)
return
}
iv = make([]byte, 12)
_, err = rand.Read(iv)
if err != nil {
panic(err)
}
ciphertext, err = gcmutil.Encrypt(getMediaRetryKey(mediaKey), iv, plaintext, []byte(messageID))
return
}
// SendMediaRetryReceipt sends a request to the phone to re-upload the media in a message.
//
// This is mostly relevant when handling history syncs and getting a 404 or 410 error downloading media.
// Rough example on how to use it (will not work out of the box, you must adjust it depending on what you need exactly):
//
// var mediaRetryCache map[types.MessageID]*waProto.ImageMessage
//
// evt, err := cli.ParseWebMessage(chatJID, historyMsg.GetMessage())
// imageMsg := evt.Message.GetImageMessage() // replace this with the part of the message you want to download
// data, err := cli.Download(imageMsg)
// if errors.Is(err, whatsmeow.ErrMediaDownloadFailedWith404) || errors.Is(err, whatsmeow.ErrMediaDownloadFailedWith410) {
// err = cli.SendMediaRetryReceipt(&evt.Info, imageMsg.GetMediaKey())
// // You need to store the event data somewhere as it's necessary for handling the retry response.
// mediaRetryCache[evt.Info.ID] = imageMsg
// }
//
// The response will come as an *events.MediaRetry. The response will then have to be decrypted
// using DecryptMediaRetryNotification and the same media key passed here. If the media retry was successful,
// the decrypted notification should contain an updated DirectPath, which can be used to download the file.
//
// func eventHandler(rawEvt interface{}) {
// switch evt := rawEvt.(type) {
// case *events.MediaRetry:
// imageMsg := mediaRetryCache[evt.MessageID]
// retryData, err := whatsmeow.DecryptMediaRetryNotification(evt, imageMsg.GetMediaKey())
// if err != nil || retryData.GetResult != waProto.MediaRetryNotification_SUCCESS {
// return
// }
// // Use the new path to download the attachment
// imageMsg.DirectPath = retryData.DirectPath
// data, err := cli.Download(imageMsg)
// // Alternatively, you can use cli.DownloadMediaWithPath and provide the individual fields manually.
// }
// }
func (cli *Client) SendMediaRetryReceipt(message *types.MessageInfo, mediaKey []byte) error {
ciphertext, iv, err := encryptMediaRetryReceipt(message.ID, mediaKey)
if err != nil {
return fmt.Errorf("failed to prepare encrypted retry receipt: %w", err)
}
ownID := cli.getOwnID().ToNonAD()
if ownID.IsEmpty() {
return ErrNotLoggedIn
}
rmrAttrs := waBinary.Attrs{
"jid": message.Chat,
"from_me": message.IsFromMe,
}
if message.IsGroup {
rmrAttrs["participant"] = message.Sender
}
encryptedRequest := []waBinary.Node{
{Tag: "enc_p", Content: ciphertext},
{Tag: "enc_iv", Content: iv},
}
err = cli.sendNode(waBinary.Node{
Tag: "receipt",
Attrs: waBinary.Attrs{
"id": message.ID,
"to": ownID,
"type": "server-error",
},
Content: []waBinary.Node{
{Tag: "encrypt", Content: encryptedRequest},
{Tag: "rmr", Attrs: rmrAttrs},
},
})
if err != nil {
return err
}
return nil
}
// DecryptMediaRetryNotification decrypts a media retry notification using the media key.
// See Client.SendMediaRetryReceipt for more info on how to use this.
func DecryptMediaRetryNotification(evt *events.MediaRetry, mediaKey []byte) (*waProto.MediaRetryNotification, error) {
var notif waProto.MediaRetryNotification
if evt.Error != nil && evt.Ciphertext == nil {
if evt.Error.Code == 2 {
return nil, ErrMediaNotAvailableOnPhone
}
return nil, fmt.Errorf("%w (code: %d)", ErrUnknownMediaRetryError, evt.Error.Code)
} else if plaintext, err := gcmutil.Decrypt(getMediaRetryKey(mediaKey), evt.IV, evt.Ciphertext, []byte(evt.MessageID)); err != nil {
return nil, fmt.Errorf("failed to decrypt notification: %w", err)
} else if err = proto.Unmarshal(plaintext, ¬if); err != nil {
return nil, fmt.Errorf("failed to unmarshal notification (invalid encryption key?): %w", err)
} else {
return ¬if, nil
}
}
func parseMediaRetryNotification(node *waBinary.Node) (*events.MediaRetry, error) {
ag := node.AttrGetter()
var evt events.MediaRetry
evt.Timestamp = ag.UnixTime("t")
evt.MessageID = types.MessageID(ag.String("id"))
if !ag.OK() {
return nil, ag.Error()
}
rmr, ok := node.GetOptionalChildByTag("rmr")
if !ok {
return nil, &ElementMissingError{Tag: "rmr", In: "retry notification"}
}
rmrAG := rmr.AttrGetter()
evt.ChatID = rmrAG.JID("jid")
evt.FromMe = rmrAG.Bool("from_me")
evt.SenderID = rmrAG.OptionalJIDOrEmpty("participant")
if !rmrAG.OK() {
return nil, fmt.Errorf("missing attributes in <rmr> tag: %w", rmrAG.Error())
}
errNode, ok := node.GetOptionalChildByTag("error")
if ok {
evt.Error = &events.MediaRetryError{
Code: errNode.AttrGetter().Int("code"),
}
return &evt, nil
}
evt.Ciphertext, ok = node.GetChildByTag("encrypt", "enc_p").Content.([]byte)
if !ok {
return nil, &ElementMissingError{Tag: "enc_p", In: fmt.Sprintf("retry notification %s", evt.MessageID)}
}
evt.IV, ok = node.GetChildByTag("encrypt", "enc_iv").Content.([]byte)
if !ok {
return nil, &ElementMissingError{Tag: "enc_iv", In: fmt.Sprintf("retry notification %s", evt.MessageID)}
}
return &evt, nil
}
func (cli *Client) handleMediaRetryNotification(node *waBinary.Node) {
evt, err := parseMediaRetryNotification(node)
if err != nil {
cli.Log.Warnf("Failed to parse media retry notification: %v", err)
return
}
cli.dispatchEvent(evt)
}
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