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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 (
"encoding/binary"
"fmt"
"time"
"go.mau.fi/libsignal/ecc"
"go.mau.fi/libsignal/keys/identity"
"go.mau.fi/libsignal/keys/prekey"
"go.mau.fi/libsignal/util/optional"
waBinary "go.mau.fi/whatsmeow/binary"
"go.mau.fi/whatsmeow/types"
"go.mau.fi/whatsmeow/util/keys"
)
const (
// WantedPreKeyCount is the number of prekeys that the client should upload to the WhatsApp servers in a single batch.
WantedPreKeyCount = 50
// MinPreKeyCount is the number of prekeys when the client will upload a new batch of prekeys to the WhatsApp servers.
MinPreKeyCount = 5
)
func (cli *Client) getServerPreKeyCount() (int, error) {
resp, err := cli.sendIQ(infoQuery{
Namespace: "encrypt",
Type: "get",
To: types.ServerJID,
Content: []waBinary.Node{
{Tag: "count"},
},
})
if err != nil {
return 0, fmt.Errorf("failed to get prekey count on server: %w", err)
}
count := resp.GetChildByTag("count")
ag := count.AttrGetter()
val := ag.Int("value")
return val, ag.Error()
}
func (cli *Client) uploadPreKeys() {
cli.uploadPreKeysLock.Lock()
defer cli.uploadPreKeysLock.Unlock()
if cli.lastPreKeyUpload.Add(10 * time.Minute).After(time.Now()) {
sc, _ := cli.getServerPreKeyCount()
if sc >= WantedPreKeyCount {
cli.Log.Debugf("Canceling prekey upload request due to likely race condition")
return
}
}
var registrationIDBytes [4]byte
binary.BigEndian.PutUint32(registrationIDBytes[:], cli.Store.RegistrationID)
preKeys, err := cli.Store.PreKeys.GetOrGenPreKeys(WantedPreKeyCount)
if err != nil {
cli.Log.Errorf("Failed to get prekeys to upload: %v", err)
return
}
cli.Log.Infof("Uploading %d new prekeys to server", len(preKeys))
_, err = cli.sendIQ(infoQuery{
Namespace: "encrypt",
Type: "set",
To: types.ServerJID,
Content: []waBinary.Node{
{Tag: "registration", Content: registrationIDBytes[:]},
{Tag: "type", Content: []byte{ecc.DjbType}},
{Tag: "identity", Content: cli.Store.IdentityKey.Pub[:]},
{Tag: "list", Content: preKeysToNodes(preKeys)},
preKeyToNode(cli.Store.SignedPreKey),
},
})
if err != nil {
cli.Log.Errorf("Failed to send request to upload prekeys: %v", err)
return
}
cli.Log.Debugf("Got response to uploading prekeys")
err = cli.Store.PreKeys.MarkPreKeysAsUploaded(preKeys[len(preKeys)-1].KeyID)
if err != nil {
cli.Log.Warnf("Failed to mark prekeys as uploaded: %v", err)
}
cli.lastPreKeyUpload = time.Now()
}
type preKeyResp struct {
bundle *prekey.Bundle
err error
}
func (cli *Client) fetchPreKeys(users []types.JID) (map[types.JID]preKeyResp, error) {
requests := make([]waBinary.Node, len(users))
for i, user := range users {
requests[i].Tag = "user"
requests[i].Attrs = waBinary.Attrs{
"jid": user,
"reason": "identity",
}
}
resp, err := cli.sendIQ(infoQuery{
Namespace: "encrypt",
Type: "get",
To: types.ServerJID,
Content: []waBinary.Node{{
Tag: "key",
Content: requests,
}},
})
if err != nil {
return nil, fmt.Errorf("failed to send prekey request: %w", err)
} else if len(resp.GetChildren()) == 0 {
return nil, fmt.Errorf("got empty response to prekey request")
}
list := resp.GetChildByTag("list")
respData := make(map[types.JID]preKeyResp)
for _, child := range list.GetChildren() {
if child.Tag != "user" {
continue
}
jid := child.AttrGetter().JID("jid")
jid.AD = true
bundle, err := nodeToPreKeyBundle(uint32(jid.Device), child)
respData[jid] = preKeyResp{bundle, err}
}
return respData, nil
}
func preKeyToNode(key *keys.PreKey) waBinary.Node {
var keyID [4]byte
binary.BigEndian.PutUint32(keyID[:], key.KeyID)
node := waBinary.Node{
Tag: "key",
Content: []waBinary.Node{
{Tag: "id", Content: keyID[1:]},
{Tag: "value", Content: key.Pub[:]},
},
}
if key.Signature != nil {
node.Tag = "skey"
node.Content = append(node.GetChildren(), waBinary.Node{
Tag: "signature",
Content: key.Signature[:],
})
}
return node
}
func nodeToPreKeyBundle(deviceID uint32, node waBinary.Node) (*prekey.Bundle, error) {
errorNode, ok := node.GetOptionalChildByTag("error")
if ok && errorNode.Tag == "error" {
return nil, fmt.Errorf("got error getting prekeys: %s", errorNode.XMLString())
}
registrationBytes, ok := node.GetChildByTag("registration").Content.([]byte)
if !ok || len(registrationBytes) != 4 {
return nil, fmt.Errorf("invalid registration ID in prekey response")
}
registrationID := binary.BigEndian.Uint32(registrationBytes)
keysNode, ok := node.GetOptionalChildByTag("keys")
if !ok {
keysNode = node
}
identityKeyRaw, ok := keysNode.GetChildByTag("identity").Content.([]byte)
if !ok || len(identityKeyRaw) != 32 {
return nil, fmt.Errorf("invalid identity key in prekey response")
}
identityKeyPub := *(*[32]byte)(identityKeyRaw)
preKey, err := nodeToPreKey(keysNode.GetChildByTag("key"))
if err != nil {
return nil, fmt.Errorf("invalid prekey in prekey response: %w", err)
}
signedPreKey, err := nodeToPreKey(keysNode.GetChildByTag("skey"))
if err != nil {
return nil, fmt.Errorf("invalid signed prekey in prekey response: %w", err)
}
return prekey.NewBundle(registrationID, deviceID,
optional.NewOptionalUint32(preKey.KeyID), signedPreKey.KeyID,
ecc.NewDjbECPublicKey(*preKey.Pub), ecc.NewDjbECPublicKey(*signedPreKey.Pub), *signedPreKey.Signature,
identity.NewKey(ecc.NewDjbECPublicKey(identityKeyPub))), nil
}
func nodeToPreKey(node waBinary.Node) (*keys.PreKey, error) {
key := keys.PreKey{
KeyPair: keys.KeyPair{},
KeyID: 0,
Signature: nil,
}
if id := node.GetChildByTag("id"); id.Tag != "id" {
return nil, fmt.Errorf("prekey node doesn't contain ID tag")
} else if idBytes, ok := id.Content.([]byte); !ok {
return nil, fmt.Errorf("prekey ID has unexpected content (%T)", id.Content)
} else if len(idBytes) != 3 {
return nil, fmt.Errorf("prekey ID has unexpected number of bytes (%d, expected 3)", len(idBytes))
} else {
key.KeyID = binary.BigEndian.Uint32(append([]byte{0}, idBytes...))
}
if pubkey := node.GetChildByTag("value"); pubkey.Tag != "value" {
return nil, fmt.Errorf("prekey node doesn't contain value tag")
} else if pubkeyBytes, ok := pubkey.Content.([]byte); !ok {
return nil, fmt.Errorf("prekey value has unexpected content (%T)", pubkey.Content)
} else if len(pubkeyBytes) != 32 {
return nil, fmt.Errorf("prekey value has unexpected number of bytes (%d, expected 32)", len(pubkeyBytes))
} else {
key.KeyPair.Pub = (*[32]byte)(pubkeyBytes)
}
if node.Tag == "skey" {
if sig := node.GetChildByTag("signature"); sig.Tag != "signature" {
return nil, fmt.Errorf("prekey node doesn't contain signature tag")
} else if sigBytes, ok := sig.Content.([]byte); !ok {
return nil, fmt.Errorf("prekey signature has unexpected content (%T)", sig.Content)
} else if len(sigBytes) != 64 {
return nil, fmt.Errorf("prekey signature has unexpected number of bytes (%d, expected 64)", len(sigBytes))
} else {
key.Signature = (*[64]byte)(sigBytes)
}
}
return &key, nil
}
func preKeysToNodes(prekeys []*keys.PreKey) []waBinary.Node {
nodes := make([]waBinary.Node, len(prekeys))
for i, key := range prekeys {
nodes[i] = preKeyToNode(key)
}
return nodes
}
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