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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 appstate implements encoding and decoding WhatsApp's app state patches.
package appstate
import (
"encoding/base64"
"sync"
"go.mau.fi/whatsmeow/store"
"go.mau.fi/whatsmeow/util/hkdfutil"
waLog "go.mau.fi/whatsmeow/util/log"
)
// WAPatchName represents a type of app state patch.
type WAPatchName string
const (
// WAPatchCriticalBlock contains the user's settings like push name and locale.
WAPatchCriticalBlock WAPatchName = "critical_block"
// WAPatchCriticalUnblockLow contains the user's contact list.
WAPatchCriticalUnblockLow WAPatchName = "critical_unblock_low"
// WAPatchRegularLow contains some local chat settings like pin, archive status, and the setting of whether to unarchive chats when messages come in.
WAPatchRegularLow WAPatchName = "regular_low"
// WAPatchRegularHigh contains more local chat settings like mute status and starred messages.
WAPatchRegularHigh WAPatchName = "regular_high"
// WAPatchRegular contains protocol info about app state patches like key expiration.
WAPatchRegular WAPatchName = "regular"
)
// AllPatchNames contains all currently known patch state names.
var AllPatchNames = [...]WAPatchName{WAPatchCriticalBlock, WAPatchCriticalUnblockLow, WAPatchRegularHigh, WAPatchRegular, WAPatchRegularLow}
type Processor struct {
keyCache map[string]ExpandedAppStateKeys
keyCacheLock sync.Mutex
Store *store.Device
Log waLog.Logger
}
func NewProcessor(store *store.Device, log waLog.Logger) *Processor {
return &Processor{
keyCache: make(map[string]ExpandedAppStateKeys),
Store: store,
Log: log,
}
}
type ExpandedAppStateKeys struct {
Index []byte
ValueEncryption []byte
ValueMAC []byte
SnapshotMAC []byte
PatchMAC []byte
}
func expandAppStateKeys(keyData []byte) (keys ExpandedAppStateKeys) {
appStateKeyExpanded := hkdfutil.SHA256(keyData, nil, []byte("WhatsApp Mutation Keys"), 160)
return ExpandedAppStateKeys{appStateKeyExpanded[0:32], appStateKeyExpanded[32:64], appStateKeyExpanded[64:96], appStateKeyExpanded[96:128], appStateKeyExpanded[128:160]}
}
func (proc *Processor) getAppStateKey(keyID []byte) (keys ExpandedAppStateKeys, err error) {
keyCacheID := base64.RawStdEncoding.EncodeToString(keyID)
var ok bool
proc.keyCacheLock.Lock()
defer proc.keyCacheLock.Unlock()
keys, ok = proc.keyCache[keyCacheID]
if !ok {
var keyData *store.AppStateSyncKey
keyData, err = proc.Store.AppStateKeys.GetAppStateSyncKey(keyID)
if keyData != nil {
keys = expandAppStateKeys(keyData.Data)
proc.keyCache[keyCacheID] = keys
} else if err == nil {
err = ErrKeyNotFound
}
}
return
}
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