Validate Merkle proofs and updates in TLB validate (#1479)

* Validate Merkle proofs and updates in TLB validate

* Fix out-of-bound access in tl_jni_object.cpp

Author: SpyCheese

crypto/block/block.tlb

@@ -296,7 +296,7 @@ transaction$0111 account_addr:bits256 lt:uint64
   total_fees:CurrencyCollection state_update:^(HASH_UPDATE Account)
   description:^TransactionDescr = Transaction;
 
-!merkle_update#02 {X:Type} old_hash:bits256 new_hash:bits256
+!merkle_update#04 {X:Type} old_hash:bits256 new_hash:bits256 old_depth:uint16 new_depth:uint16
   old:^X new:^X = MERKLE_UPDATE X;
 update_hashes#72 {X:Type} old_hash:bits256 new_hash:bits256
   = HASH_UPDATE X;

crypto/tl/tlbc-gen-cpp.cpp

@@ -2074,7 +2074,7 @@ void CppTypeCode::generate_skip_field(const Constructor& constr, const Field& fi
     output_cpp_expr(ss, expr, 100);
     ss << '.';
   }
-  ss << "validate_skip_ref(ops, cs, weak)" << tail;
+  ss << "validate_skip_ref(ops, cs, " << (constr.is_special ? "true" : "weak") << ")" << tail;
   actions += Action{ss.str()};
 }
 

crypto/tl/tlblib.cpp

@@ -133,7 +133,13 @@ bool TLB::validate_ref_internal(int* ops, Ref<vm::Cell> cell_ref, bool weak) con
   }
   bool is_special;
   auto cs = load_cell_slice_special(std::move(cell_ref), is_special);
-  return always_special() ? is_special : (is_special ? weak : (validate_skip(ops, cs) && cs.empty_ext()));
+  if (cs.special_type() == vm::Cell::SpecialType::PrunnedBranch && weak) {
+    return true;
+  }
+  if (always_special() != is_special) {
+    return false;
+  }
+  return validate_skip(ops, cs, weak) && cs.empty_ext();
 }
 
 bool TLB::print_skip(PrettyPrinter& pp, vm::CellSlice& cs) const {

tl/tl/tl_jni_object.cpp

@@ -115,8 +115,9 @@ static size_t get_utf8_from_utf16_length(const jchar *p, jsize len) {
   for (jsize i = 0; i < len; i++) {
     unsigned int cur = p[i];
     if ((cur & 0xF800) == 0xD800) {
+      ++i;
       if (i < len) {
-        unsigned int next = p[++i];
+        unsigned int next = p[i];
         if ((next & 0xFC00) == 0xDC00 && (cur & 0x400) == 0) {
           result += 4;
           continue;