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Merge pull request #17 from iamxvbaba/dev

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fix: sync lenient DC-ID validation for key exchange
This commit is contained in:
yialdd 2026-07-24 23:08:57 +08:00 • committed by GitHub
commit 5dcdb57e4c
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5 changed files with 82 additions and 6 deletions
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8
internal/config/config.go
View file

@ -31,6 +31,13 @@ type Config struct {
RSAKeyPath string
// DC 是本 server 的 DC ID。
DC int
// StrictDCCheck turns on exact DC-ID validation for the permanent-key
// exchange (default off = lenient). See mtprotoedge.Options.StrictDC doc
// for the full rationale: telesrv is always a single physical backend, but
// many client forks alias dc_id 1..5 to it, so a mismatched client-chosen
// dc_id is expected, not an attack — strict mode exists only for a
// hypothetical future real multi-DC deployment.
StrictDCCheck bool
// MTProtoMaxConnections / PerIP 覆盖 raw Accept、codec sniff、握手到认证 session
// 的完整物理连接生命周期；负数关闭对应 admission 上限。
MTProtoMaxConnections int
@ -465,6 +472,7 @@ func Load() (Config, error) {
AdvertiseIP: envOr("TELESRV_ADVERTISE_IP", "127.0.0.1"),
RSAKeyPath: envOr("TELESRV_RSA_KEY", "data/server_rsa.pem"),
DC: envIntOr("TELESRV_DC", 2),
StrictDCCheck: envBoolOr("TELESRV_STRICT_DC_CHECK", false),
MTProtoMaxConnections: envIntOr("TELESRV_MTPROTO_MAX_CONNECTIONS", 200000),
MTProtoMaxConnectionsPerIP: envIntOr("TELESRV_MTPROTO_MAX_CONNECTIONS_PER_IP", 4096),
MTProtoMaxConcurrentHandshakes: envIntOr("TELESRV_MTPROTO_MAX_CONCURRENT_HANDSHAKES", 256),

26
internal/mtprotoedge/exchange_compat.go
View file

@ -27,9 +27,12 @@ import (
//
// DrKLO Android marks media temporary auth-key exchange with a negative DC in
// p_q_inner_data_temp_dc (for example DC 2 -> -2). gotd v0.158.0 validates this
// field by exact equality and rejects that legitimate media-temp path. Keep the
// permanent-key check strict, but allow temp-key DC values whose absolute value
// matches this server DC.
// field by exact equality and rejects that legitimate media-temp path. The
// temp-key DC check accepts any value whose absolute value matches this
// server DC. The permanent-key check is lenient by default too (see
// Options.StrictDC doc) — self-hosted single-server deployments commonly
// have clients that alias dc_id 1..5 to the one backend, so a client-chosen
// dc_id that isn't our configured DC is expected, not an error.
func (s *Server) runServerExchange(ctx context.Context, conn transport.Conn) (exchange.ServerExchangeResult, error) {
ex := serverExchangeCompat{
conn: conn,
@ -38,6 +41,7 @@ func (s *Server) runServerExchange(ctx context.Context, conn transport.Conn) (ex
timeout: exchange.DefaultTimeout,
key: s.key,
dc: s.dc,
strictDC: s.strictDC,
log: s.log.Named("exchange"),
rng: compatServerRNG{rand: s.rand},
commitKey: s.commitExchangeAuthKey,
@ -65,6 +69,7 @@ type serverExchangeCompat struct {
timeout time.Duration
key exchange.PrivateKey
dc int
strictDC bool
log *zap.Logger
rng compatServerRNG
commitKey func(context.Context, exchange.ServerExchangeResult, int) error
@ -345,10 +350,23 @@ func (s serverExchangeCompat) validatePQInnerDataDC(d mt.PQInnerDataClass) error
switch innerDataDC := d.(type) {
case *mt.PQInnerDataDC:
if innerDataDC.DC != s.dc {
if !s.strictDC {
// Lenient by default (Options.StrictDC doc has the full
// rationale): telesrv is a single physical backend, and
// self-hosted client forks commonly alias dc_id 1..5 to this
// one server, so a client-chosen dc_id that isn't our
// configured DC is expected, not an error. dc_id plays no
// role in key derivation, so accepting it doesn't weaken the
// exchange.
s.log.Debug("Accepted permanent auth key DC mismatch (lenient mode)",
zap.Int("server_dc", s.dc),
zap.Int("client_dc", innerDataDC.DC))
return nil
}
return wrongDCError(s.dc, innerDataDC.DC)
}
case *mt.PQInnerDataTempDC:
if !sameDCByAbs(innerDataDC.DC, s.dc) {
if !sameDCByAbs(innerDataDC.DC, s.dc) && s.strictDC {
return wrongDCError(s.dc, innerDataDC.DC)
}
if innerDataDC.DC < 0 {

36
internal/mtprotoedge/exchange_test.go
View file

@ -366,8 +366,8 @@ func TestKeyExchangeAcceptsAndroidMediaTempNegativeDC(t *testing.T) {
}
}
func TestKeyExchangeRejectsWrongNegativeTempDC(t *testing.T) {
ex := serverExchangeCompat{dc: 2, log: zaptest.NewLogger(t)}
func TestKeyExchangeRejectsWrongNegativeTempDCWhenStrict(t *testing.T) {
ex := serverExchangeCompat{dc: 2, strictDC: true, log: zaptest.NewLogger(t)}
err := ex.validatePQInnerDataDC(&mt.PQInnerDataTempDC{DC: -3})
var exErr *exchange.ServerExchangeError
if !errors.As(err, &exErr) {
@ -378,6 +378,38 @@ func TestKeyExchangeRejectsWrongNegativeTempDC(t *testing.T) {
}
}
// TestKeyExchangeAcceptsMismatchedDCByDefault asserts that, in the default
// lenient mode, neither permanent nor temp key exchange requires dc_id to
// equal the server's configured DC. telesrv is always a single physical
// backend; self-hosted client forks commonly alias dc_id 1..5 to it (see
// Options.StrictDC doc), so a mismatched client-chosen dc_id must not be
// rejected — doing so previously broke every account whose client picked a
// starting dc_id other than the server's.
func TestKeyExchangeAcceptsMismatchedDCByDefault(t *testing.T) {
ex := serverExchangeCompat{dc: 2, log: zaptest.NewLogger(t)}
if err := ex.validatePQInnerDataDC(&mt.PQInnerDataDC{DC: 3}); err != nil {
t.Fatalf("permanent DC mismatch: err = %v, want nil (lenient by default)", err)
}
if err := ex.validatePQInnerDataDC(&mt.PQInnerDataTempDC{DC: -3}); err != nil {
t.Fatalf("temp DC mismatch: err = %v, want nil (lenient by default)", err)
}
}
// TestKeyExchangeRejectsMismatchedPermanentDCWhenStrict asserts that
// strictDC=true still enforces exact DC-ID equality for permanent-key
// exchange (kept for a hypothetical future real multi-DC deployment).
func TestKeyExchangeRejectsMismatchedPermanentDCWhenStrict(t *testing.T) {
ex := serverExchangeCompat{dc: 2, strictDC: true, log: zaptest.NewLogger(t)}
err := ex.validatePQInnerDataDC(&mt.PQInnerDataDC{DC: 3})
var exErr *exchange.ServerExchangeError
if !errors.As(err, &exErr) {
t.Fatalf("err = %T %v, want ServerExchangeError", err, err)
}
if exErr.Code != codec.CodeWrongDC {
t.Fatalf("error code = %d, want %d", exErr.Code, codec.CodeWrongDC)
}
}
func TestDecodeCompatPQInnerDataTemp(t *testing.T) {
want := mt.PQInnerData{
Pq: []byte{0x0f},

17
internal/mtprotoedge/server.go
View file

@ -303,6 +303,21 @@ type Options struct {
// DC 是本 server 的 DC ID。默认 2。
DC int
// StrictDC turns on exact DC-ID validation for the permanent-key exchange
// (default off = lenient). telesrv is always a single physical backend —
// there is no real multi-DC federation behind it — but self-hosted client
// forks commonly run in "single-server backend" mode, where dc_id 1..5 all
// alias to this one server so that any old data referencing a specific
// dc_id still resolves correctly. When a client adds a new local account it
// picks its own starting dc_id (its usual multi-DC load-spreading
// behavior, unrelated to which physical server it's actually talking to)
// — that choice is not guaranteed to equal our configured DC. Strict
// validation would reject those accounts with "-444 wrong dc_id" even
// though they are connecting to the right (and only) server; dc_id is a
// client-side routing label here, not part of key derivation, so
// accepting the mismatch does not weaken the exchange. The switch exists
// for a hypothetical future real multi-DC deployment.
StrictDC bool
// RSAKey 是 server RSA 私钥，用于密钥交换。nil 时无法完成握手。
RSAKey *rsa.PrivateKey
// AuthKeys 持久化 auth key。默认内存实现。
@ -482,6 +497,7 @@ type Server struct {
outboundScratchPool *outboundScratchPool
dc int
strictDC bool
key exchange.PrivateKey
authKeys store.AuthKeyStore
conns *SessionManager
@ -533,6 +549,7 @@ func New(opts Options) *Server {
outboundControlBudget: newOutboundTrackedBudget(defaultOutboundControlMaxBytes),
outboundScratchPool: newOutboundScratchPool(opts.OutboundWriteGlobalMaxBytes),
dc: opts.DC,
strictDC: opts.StrictDC,
key: exchange.PrivateKey{RSA: opts.RSAKey},
authKeys: opts.AuthKeys,
conns: conns,