decrypt_push_payload: bugfix

GitOrigin-RevId: 20b8152e77a881937edd1914521408c8aad506fe

Author: arseny30

td/telegram/NotificationManager.cpp

@@ -2364,7 +2364,10 @@ Result<string> NotificationManager::decrypt_push_payload(int64 encryption_key_id
   if (result.type() != mtproto::Transport::ReadResult::Packet) {
     return Status::Error(400, "Wrong packet type");
   }
-  return result.packet().str();
+  if (result.packet().size() < 4) {
+    return Status::Error(400, "Packet is too small");
+  }
+  return result.packet().substr(4).str();
 }
 
 void NotificationManager::before_get_difference() {

test/mtproto.cpp

@@ -448,8 +448,8 @@ TEST(Mtproto, notifications) {
       "H0yJkEMoKRgaF9NaYI4u26oIQ-Ez46kTVU-R7e3acdofOJKm7HIKan_5ZMg82Dvec2M6vc_"
       "I54Vs28iBx8IbBO1y5z9WSScgW3JCvFFKP2MXIu7Jow5-cpUx6jXdzwRUb9RDApwAFKi45zpv8eb3uPCDAmIQ";
   vector<string> decrypted_payloads = {
-      "fwAAAHsibG9jX2tleSI6Ik1FU1NBR0VfVEVYVCIsImxvY19hcmdzIjpbIkFyc2VueSBTbWlybm92IiwiYWJjZGVmZyJdLCJjdXN0b20iOnsibXNn"
-      "X2lkIjoiNTkwMDQ3IiwiZnJvbV9pZCI6IjYyODE0In0sImJhZGdlIjoiNDA5In0",
+      "eyJsb2Nfa2V5IjoiTUVTU0FHRV9URVhUIiwibG9jX2FyZ3MiOlsiQXJzZW55IFNtaXJub3YiLCJhYmNkZWZnIl0sImN1c3RvbSI6eyJtc2dfaWQi"
+      "OiI1OTAwNDciLCJmcm9tX2lkIjoiNjI4MTQifSwiYmFkZ2UiOiI0MDkifQ",
       "eyJsb2Nfa2V5IjoiIiwibG9jX2FyZ3MiOltdLCJjdXN0b20iOnsiY2hhbm5lbF9pZCI6IjExNzY4OTU0OTciLCJtYXhfaWQiOiIxMzU5In0sImJh"
       "ZGdlIjoiMCJ9"};
   key = base64url_decode(key).move_as_ok();