mirror of
https://github.com/cwinfo/matterbridge.git
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268 lines
9.7 KiB
Go
268 lines
9.7 KiB
Go
// Copyright (c) 2022 Tulir Asokan
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this
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// file, You can obtain one at http://mozilla.org/MPL/2.0/.
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package whatsmeow
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import (
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"crypto/rand"
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"crypto/sha256"
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"fmt"
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"time"
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"google.golang.org/protobuf/proto"
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waProto "go.mau.fi/whatsmeow/binary/proto"
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"go.mau.fi/whatsmeow/types"
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"go.mau.fi/whatsmeow/types/events"
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"go.mau.fi/whatsmeow/util/gcmutil"
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"go.mau.fi/whatsmeow/util/hkdfutil"
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)
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type MsgSecretType string
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const (
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EncSecretPollVote MsgSecretType = "Poll Vote"
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EncSecretReaction MsgSecretType = "Enc Reaction"
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)
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func generateMsgSecretKey(
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modificationType MsgSecretType, modificationSender types.JID,
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origMsgID types.MessageID, origMsgSender types.JID, origMsgSecret []byte,
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) ([]byte, []byte) {
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origMsgSenderStr := origMsgSender.ToNonAD().String()
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modificationSenderStr := modificationSender.ToNonAD().String()
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useCaseSecret := make([]byte, 0, len(origMsgID)+len(origMsgSenderStr)+len(modificationSenderStr)+len(modificationType))
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useCaseSecret = append(useCaseSecret, origMsgID...)
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useCaseSecret = append(useCaseSecret, origMsgSenderStr...)
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useCaseSecret = append(useCaseSecret, modificationSenderStr...)
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useCaseSecret = append(useCaseSecret, modificationType...)
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secretKey := hkdfutil.SHA256(origMsgSecret, nil, useCaseSecret, 32)
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additionalData := []byte(fmt.Sprintf("%s\x00%s", origMsgID, modificationSenderStr))
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return secretKey, additionalData
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}
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func getOrigSenderFromKey(msg *events.Message, key *waProto.MessageKey) (types.JID, error) {
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if key.GetFromMe() {
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// fromMe always means the poll and vote were sent by the same user
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return msg.Info.Sender, nil
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} else if msg.Info.Chat.Server == types.DefaultUserServer {
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sender, err := types.ParseJID(key.GetRemoteJid())
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if err != nil {
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return types.EmptyJID, fmt.Errorf("failed to parse JID %q of original message sender: %w", key.GetRemoteJid(), err)
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}
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return sender, nil
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} else {
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sender, err := types.ParseJID(key.GetParticipant())
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if sender.Server != types.DefaultUserServer {
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err = fmt.Errorf("unexpected server")
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}
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if err != nil {
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return types.EmptyJID, fmt.Errorf("failed to parse JID %q of original message sender: %w", key.GetParticipant(), err)
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}
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return sender, nil
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}
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}
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type messageEncryptedSecret interface {
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GetEncIv() []byte
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GetEncPayload() []byte
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}
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func (cli *Client) decryptMsgSecret(msg *events.Message, useCase MsgSecretType, encrypted messageEncryptedSecret, origMsgKey *waProto.MessageKey) ([]byte, error) {
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pollSender, err := getOrigSenderFromKey(msg, origMsgKey)
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if err != nil {
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return nil, err
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}
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baseEncKey, err := cli.Store.MsgSecrets.GetMessageSecret(msg.Info.Chat, pollSender, origMsgKey.GetId())
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if err != nil {
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return nil, fmt.Errorf("failed to get original message secret key: %w", err)
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} else if baseEncKey == nil {
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return nil, ErrOriginalMessageSecretNotFound
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}
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secretKey, additionalData := generateMsgSecretKey(useCase, msg.Info.Sender, origMsgKey.GetId(), pollSender, baseEncKey)
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plaintext, err := gcmutil.Decrypt(secretKey, encrypted.GetEncIv(), encrypted.GetEncPayload(), additionalData)
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if err != nil {
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return nil, fmt.Errorf("failed to decrypt secret message: %w", err)
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}
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return plaintext, nil
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}
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func (cli *Client) encryptMsgSecret(chat, origSender types.JID, origMsgID types.MessageID, useCase MsgSecretType, plaintext []byte) (ciphertext, iv []byte, err error) {
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ownID := *cli.Store.ID
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baseEncKey, err := cli.Store.MsgSecrets.GetMessageSecret(chat, origSender, origMsgID)
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if err != nil {
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return nil, nil, fmt.Errorf("failed to get original message secret key: %w", err)
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} else if baseEncKey == nil {
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return nil, nil, ErrOriginalMessageSecretNotFound
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}
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secretKey, additionalData := generateMsgSecretKey(useCase, ownID, origMsgID, origSender, baseEncKey)
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iv = make([]byte, 12)
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_, err = rand.Read(iv)
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if err != nil {
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return nil, nil, fmt.Errorf("failed to generate iv: %w", err)
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}
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ciphertext, err = gcmutil.Encrypt(secretKey, iv, plaintext, additionalData)
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if err != nil {
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return nil, nil, fmt.Errorf("failed to encrypt secret message: %w", err)
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}
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return ciphertext, iv, nil
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}
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// DecryptReaction decrypts a reaction update message. This form of reactions hasn't been rolled out yet,
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// so this function is likely not of much use.
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//
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// if evt.Message.GetEncReactionMessage() != nil {
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// reaction, err := cli.DecryptReaction(evt)
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// if err != nil {
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// fmt.Println(":(", err)
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// return
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// }
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// fmt.Printf("Reaction message: %+v\n", reaction)
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// }
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func (cli *Client) DecryptReaction(reaction *events.Message) (*waProto.ReactionMessage, error) {
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encReaction := reaction.Message.GetEncReactionMessage()
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if encReaction != nil {
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return nil, ErrNotEncryptedReactionMessage
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}
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plaintext, err := cli.decryptMsgSecret(reaction, EncSecretReaction, encReaction, encReaction.GetTargetMessageKey())
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if err != nil {
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return nil, fmt.Errorf("failed to decrypt reaction: %w", err)
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}
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var msg waProto.ReactionMessage
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err = proto.Unmarshal(plaintext, &msg)
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if err != nil {
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return nil, fmt.Errorf("failed to decode reaction protobuf: %w", err)
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}
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return &msg, nil
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}
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// DecryptPollVote decrypts a poll update message. The vote itself includes SHA-256 hashes of the selected options.
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//
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// if evt.Message.GetPollUpdateMessage() != nil {
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// pollVote, err := cli.DecryptPollVote(evt)
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// if err != nil {
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// fmt.Println(":(", err)
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// return
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// }
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// fmt.Println("Selected hashes:")
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// for _, hash := range pollVote.GetSelectedOptions() {
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// fmt.Printf("- %X\n", hash)
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// }
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// }
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func (cli *Client) DecryptPollVote(vote *events.Message) (*waProto.PollVoteMessage, error) {
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pollUpdate := vote.Message.GetPollUpdateMessage()
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if pollUpdate == nil {
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return nil, ErrNotPollUpdateMessage
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}
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plaintext, err := cli.decryptMsgSecret(vote, EncSecretPollVote, pollUpdate.GetVote(), pollUpdate.GetPollCreationMessageKey())
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if err != nil {
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return nil, fmt.Errorf("failed to decrypt poll vote: %w", err)
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}
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var msg waProto.PollVoteMessage
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err = proto.Unmarshal(plaintext, &msg)
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if err != nil {
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return nil, fmt.Errorf("failed to decode poll vote protobuf: %w", err)
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}
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return &msg, nil
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}
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func getKeyFromInfo(msgInfo *types.MessageInfo) *waProto.MessageKey {
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creationKey := &waProto.MessageKey{
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RemoteJid: proto.String(msgInfo.Chat.String()),
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FromMe: proto.Bool(msgInfo.IsFromMe),
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Id: proto.String(msgInfo.ID),
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}
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if msgInfo.IsGroup {
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creationKey.Participant = proto.String(msgInfo.Sender.String())
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}
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return creationKey
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}
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// HashPollOptions hashes poll option names using SHA-256 for voting.
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// This is used by BuildPollVote to convert selected option names to hashes.
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func HashPollOptions(optionNames []string) [][]byte {
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optionHashes := make([][]byte, len(optionNames))
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for i, option := range optionNames {
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optionHash := sha256.Sum256([]byte(option))
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optionHashes[i] = optionHash[:]
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}
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return optionHashes
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}
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// BuildPollVote builds a poll vote message using the given poll message info and option names.
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// The built message can be sent normally using Client.SendMessage.
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//
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// For example, to vote for the first option after receiving a message event (*events.Message):
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//
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// if evt.Message.GetPollCreationMessage() != nil {
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// pollVoteMsg, err := cli.BuildPollVote(&evt.Info, []string{evt.Message.GetPollCreationMessage().GetOptions()[0].GetOptionName()})
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// if err != nil {
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// fmt.Println(":(", err)
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// return
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// }
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// resp, err := cli.SendMessage(context.Background(), evt.Info.Chat, "", pollVoteMsg)
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// }
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func (cli *Client) BuildPollVote(pollInfo *types.MessageInfo, optionNames []string) (*waProto.Message, error) {
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pollUpdate, err := cli.EncryptPollVote(pollInfo, &waProto.PollVoteMessage{
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SelectedOptions: HashPollOptions(optionNames),
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})
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return &waProto.Message{PollUpdateMessage: pollUpdate}, err
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}
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// BuildPollCreation builds a poll creation message with the given poll name, options and maximum number of selections.
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// The built message can be sent normally using Client.SendMessage.
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//
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// resp, err := cli.SendMessage(context.Background(), chat, "", cli.BuildPollCreation("meow?", []string{"yes", "no"}, 1))
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func (cli *Client) BuildPollCreation(name string, optionNames []string, selectableOptionCount int) *waProto.Message {
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msgSecret := make([]byte, 32)
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_, err := rand.Read(msgSecret)
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if err != nil {
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panic(err)
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}
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if selectableOptionCount < 0 || selectableOptionCount > len(optionNames) {
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selectableOptionCount = 0
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}
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options := make([]*waProto.PollCreationMessage_Option, len(optionNames))
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for i, option := range optionNames {
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options[i] = &waProto.PollCreationMessage_Option{OptionName: proto.String(option)}
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}
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return &waProto.Message{
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PollCreationMessage: &waProto.PollCreationMessage{
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Name: proto.String(name),
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Options: options,
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SelectableOptionsCount: proto.Uint32(uint32(selectableOptionCount)),
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},
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MessageContextInfo: &waProto.MessageContextInfo{
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MessageSecret: msgSecret,
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},
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}
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}
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// EncryptPollVote encrypts a poll vote message. This is a slightly lower-level function, using BuildPollVote is recommended.
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func (cli *Client) EncryptPollVote(pollInfo *types.MessageInfo, vote *waProto.PollVoteMessage) (*waProto.PollUpdateMessage, error) {
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plaintext, err := proto.Marshal(vote)
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if err != nil {
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return nil, fmt.Errorf("failed to marshal poll vote protobuf: %w", err)
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}
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ciphertext, iv, err := cli.encryptMsgSecret(pollInfo.Chat, pollInfo.Sender, pollInfo.ID, EncSecretPollVote, plaintext)
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if err != nil {
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return nil, fmt.Errorf("failed to encrypt poll vote: %w", err)
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}
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return &waProto.PollUpdateMessage{
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PollCreationMessageKey: getKeyFromInfo(pollInfo),
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Vote: &waProto.PollEncValue{
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EncPayload: ciphertext,
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EncIv: iv,
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},
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SenderTimestampMs: proto.Int64(time.Now().UnixMilli()),
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}, nil
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}
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