Fixed cross-datacenter WebAuthn login.

Telegram/SourceFiles/data/components/passkeys.cpp

@@ -11,6 +11,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "data/data_passkey_deserialize.h"
 #include "main/main_app_config.h"
 #include "main/main_session.h"
+#include "mtproto/mtproto_auth_key.h"
 #include "platform/platform_webauthn.h"
 
 namespace Data {
@@ -165,10 +166,14 @@ void FinishPasskeyLogin(
 		Fn<void(QString)> fail) {
 	const auto userHandleStr = QString::fromUtf8(result.userHandle);
 	const auto parts = userHandleStr.split(':');
-	if (parts.size() != 2) {
+	auto userDcOk = false;
+	const auto userDc = (parts.size() == 2)
+		? parts[0].toInt(&userDcOk)
+		: 0;
+	if (!userDcOk || userDc <= 0 || userDc >= MTP::kDcShift) {
+		fail(u"PASSKEY_HANDLE_INVALID"_q);
 		return;
 	}
-	const auto userDc = parts[0].toInt();
 	const auto credentialIdBase64 = result.credentialId.toBase64(
 		QByteArray::Base64UrlEncoding | QByteArray::OmitTrailingEquals);
 	const auto credential = MTP_inputPasskeyCredentialPublicKey(
@@ -181,14 +186,19 @@ void FinishPasskeyLogin(
 			MTP_string(userHandleStr.toStdString())
 		)
 	);
-	const auto flags = (userDc != initialDc)
-		? MTPauth_finishPasskeyLogin::Flag::f_from_dc_id
-		: MTPauth_finishPasskeyLogin::Flags(0);
+	auto fromAuthKeyId = uint64(0);
+	for (const auto &key : api.instance().getKeysForWrite()) {
+		if (key && key->dcId() == MTP::BareDcId(initialDc)) {
+			fromAuthKeyId = key->keyId();
+			break;
+		}
+	}
+	api.instance().setMainDcId(userDc);
 	api.request(MTPauth_FinishPasskeyLogin(
-		MTP_flags(flags),
+		MTP_flags(MTPauth_finishPasskeyLogin::Flag::f_from_dc_id),
 		credential,
 		MTP_int(initialDc),
-		MTP_long(0)
+		MTP_long(int64(fromAuthKeyId))
 	)).toDC(
 		userDc
 	).done(done).fail([=](const MTP::Error &error) {