From e5c90f239f9b765c8fbc3f773a1f36010a349581 Mon Sep 17 00:00:00 2001
From: Arseny Smirnov <arseny30@gmail.com>
Date: Thu, 14 Jun 2018 18:00:10 +0300
Subject: [PATCH] Secret chats: check that his_layer is monotonic

GitOrigin-RevId: cb6b50e768a90c5afcece185bea2e7209a9939f5
---
 td/telegram/SecretChatActor.cpp        | 12 ++++++++++--
 td/telegram/SecretChatActor.h          | 13 +++++++++++--
 td/telegram/logevent/SecretChatEvent.h |  8 ++++++++
 3 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/td/telegram/SecretChatActor.cpp b/td/telegram/SecretChatActor.cpp
index 70813bdd..d6374b43 100644
--- a/td/telegram/SecretChatActor.cpp
+++ b/td/telegram/SecretChatActor.cpp
@@ -903,7 +903,7 @@ Status SecretChatActor::do_inbound_message_encrypted(std::unique_ptr<logevent::I
   return status;
 }
 
-Status SecretChatActor::check_seq_no(int in_seq_no, int out_seq_no) {
+Status SecretChatActor::check_seq_no(int in_seq_no, int out_seq_no, int32 his_layer) {
   if (in_seq_no < 0) {
     return Status::OK();
   }
@@ -924,6 +924,9 @@ Status SecretChatActor::check_seq_no(int in_seq_no, int out_seq_no) {
   if (seq_no_state_.my_out_seq_no < in_seq_no) {
     return Status::Error("in_seq_no is bigger than seq_no_state_.my_out_seq_no");
   }
+  if (his_layer < seq_no_state_.his_layer) {
+    return Status::Error("his_layer is not monotonic");
+  }
 
   return Status::OK();
 }
@@ -935,7 +938,7 @@ Status SecretChatActor::do_inbound_message_decrypted_unchecked(
   };
   auto in_seq_no = message->decrypted_message_layer->in_seq_no_;
   auto out_seq_no = message->decrypted_message_layer->out_seq_no_;
-  auto status = check_seq_no(in_seq_no, out_seq_no);
+  auto status = check_seq_no(in_seq_no, out_seq_no, message->his_layer());
   if (status.is_error() && status.code() != 2 /* not gap found */) {
     message->qts_ack.set_value(Unit());
     if (message->logevent_id()) {
@@ -1136,6 +1139,11 @@ void SecretChatActor::update_seq_no_state(const T &new_seq_no_state) {
     seq_no_state_.my_in_seq_no = new_seq_no_state.my_in_seq_no;
     seq_no_state_.my_out_seq_no = new_seq_no_state.my_out_seq_no;
 
+    auto new_his_layer = new_seq_no_state.his_layer();
+    if (new_his_layer != -1) {
+      seq_no_state_.his_layer = new_his_layer;
+    }
+
     if (seq_no_state_.his_in_seq_no != new_seq_no_state.his_in_seq_no) {
       seq_no_state_.his_in_seq_no = new_seq_no_state.his_in_seq_no;
       on_his_in_seq_no_updated();
diff --git a/td/telegram/SecretChatActor.h b/td/telegram/SecretChatActor.h
index d63459c1..ce096b50 100644
--- a/td/telegram/SecretChatActor.h
+++ b/td/telegram/SecretChatActor.h
@@ -149,6 +149,7 @@ class SecretChatActor : public NetQueryCallback {
     int32 my_in_seq_no = 0;
     int32 my_out_seq_no = 0;
     int32 his_in_seq_no = 0;
+    int32 his_layer = 0;
 
     int32 resend_end_seq_no = -1;
 
@@ -157,11 +158,12 @@ class SecretChatActor : public NetQueryCallback {
     }
     template <class StorerT>
     void store(StorerT &storer) const {
-      storer.store_int(message_id);
+      storer.store_int(message_id | HAS_LAYER);
       storer.store_int(my_in_seq_no);
       storer.store_int(my_out_seq_no);
       storer.store_int(his_in_seq_no);
       storer.store_int(resend_end_seq_no);
+      storer.store_int(his_layer);
     }
 
     template <class ParserT>
@@ -171,7 +173,14 @@ class SecretChatActor : public NetQueryCallback {
       my_out_seq_no = parser.fetch_int();
       his_in_seq_no = parser.fetch_int();
       resend_end_seq_no = parser.fetch_int();
+
+      bool has_layer = (message_id & HAS_LAYER) != 0;
+      if (has_layer) {
+        message_id &= static_cast<int32>(~HAS_LAYER);
+        his_layer = parser.fetch_int();
+      }
     }
+    static constexpr uint32 HAS_LAYER = 1u << 31;
   };
 
   struct ConfigState {
@@ -516,7 +525,7 @@ class SecretChatActor : public NetQueryCallback {
   bool seq_no_state_changed_ = false;
   int32 last_binlog_message_id_ = -1;
 
-  Status check_seq_no(int in_seq_no, int out_seq_no) TD_WARN_UNUSED_RESULT;
+  Status check_seq_no(int in_seq_no, int out_seq_no, int32 his_layer) TD_WARN_UNUSED_RESULT;
   void on_his_in_seq_no_updated();
 
   void on_seq_no_state_changed();
diff --git a/td/telegram/logevent/SecretChatEvent.h b/td/telegram/logevent/SecretChatEvent.h
index 5b12f7b0..539f9fa1 100644
--- a/td/telegram/logevent/SecretChatEvent.h
+++ b/td/telegram/logevent/SecretChatEvent.h
@@ -205,6 +205,10 @@ class InboundSecretMessage : public LogEventHelper<InboundSecretMessage, SecretC
   int32 my_out_seq_no = -1;
   int32 his_in_seq_no = -1;
 
+  int32 his_layer() const {
+    return decrypted_message_layer->layer_;
+  }
+
   EncryptedFileLocation file;
 
   bool has_encrypted_file;
@@ -292,6 +296,10 @@ class OutboundSecretMessage : public LogEventHelper<OutboundSecretMessage, Secre
   int32 my_out_seq_no = -1;
   int32 his_in_seq_no = -1;
 
+  int32 his_layer() const {
+    return -1;
+  }
+
   bool is_sent = false;
   bool is_service = false;
   bool is_rewritable = false;