Enhance metadata checks and error handling in dotnetpe

Added checks for metadata presence and improved error handling when accessing tables in dotnetpe.

Author: doomedraven

src/rat_king_parser/config_parser/utils/dotnetpe_payload.py

@@ -73,6 +73,8 @@ def __init__(
                 self.dotnetpe = dnPE(data=self.data, clr_lazy_load=True)
             else:
                 self.dotnetpe = dnPE(self.file_path, clr_lazy_load=True)
+            if not self.dotnetpe.net or not self.dotnetpe.net.mdtables:
+                raise ConfigParserException("Failed to load project as dotnet executable (missing Metadata)")
         except Exception:
             raise ConfigParserException("Failed to load project as dotnet executable")
 
@@ -88,17 +90,19 @@ def __init__(
         self._tokens = [m.token for m in self._methods_by_token]
 
         # Pre-compute FieldRva mapping for O(1) lookups
-        self._field_rva_map = {
-            row.struct.Field_Index: row.struct.Rva
-            for row in self.dotnetpe.net.mdtables.FieldRva
-        }
+        self._field_rva_map = {}
+        if getattr(self.dotnetpe.net.mdtables, "FieldRva", None):
+            self._field_rva_map = {
+                row.struct.Field_Index: row.struct.Rva
+                for row in self.dotnetpe.net.mdtables.FieldRva
+            }
 
     # Given a byte array's size and RVA, translates the RVA to the offset of
     # the byte array and returns the bytes of the array as a byte string
     def byte_array_from_size_and_rva(self, arr_size: int, arr_rva: int) -> bytes:
         arr_field_rva = self.fieldrva_from_rva(arr_rva)
         arr_offset = self.offset_from_rva(arr_field_rva)
-        return self.data[arr_offset : arr_offset + arr_size]
+        return self.data[arr_offset: arr_offset + arr_size]
 
     # Given an offset, and either a terminating offset or delimiter, extracts
     # the byte string
@@ -122,7 +126,10 @@ def byte_string_from_offset(
     # Given an RVA, derives the corresponding Field name
     def field_name_from_rva(self, rva: int) -> str:
         try:
-            return self.dotnetpe.net.mdtables.Field.rows[
+            field_table = getattr(self.dotnetpe.net.mdtables, "Field", None)
+            if not field_table:
+                raise ConfigParserException(f"Could not find Field table for RVA {rva}")
+            return field_table.rows[
                 (rva ^ MDT_FIELD_DEF) - 1
             ].Name.value
         except Exception:
@@ -141,8 +148,11 @@ def _generate_method_list(
         self,
     ) -> list[DotNetPEMethod]:
         method_objs = []
+        method_def_table = getattr(self.dotnetpe.net.mdtables, "MethodDef", None)
+        if not method_def_table:
+            return method_objs
 
-        for idx, method in enumerate(self.dotnetpe.net.mdtables.MethodDef.rows):
+        for idx, method in enumerate(method_def_table.rows):
             method_offset = self.offset_from_rva(method.Rva)
 
             # Parse size from flags
@@ -152,7 +162,7 @@ def _generate_method_list(
                 method_size = flags >> 2
             elif flags & 3 == 3:  # Fat format (add 12-byte header)
                 method_size = 12 + bytes_to_int(
-                    self.data[method_offset + 4 : method_offset + 8]
+                    self.data[method_offset + 4: method_offset + 8]
                 )
 
             method_objs.append(
@@ -252,21 +262,28 @@ def custom_attribute_from_type(self, typespacename: str, typename: str) -> dict:
         config = {}
         try:
             ca_map = {}
-            for ca in self.dotnetpe.net.mdtables.CustomAttribute.rows:
-                idx = ca.Parent.row_index
-                if idx not in ca_map:
-                    ca_map[idx] = []
-                ca_map[idx].append(ca)
+            ca_table = getattr(self.dotnetpe.net.mdtables, "CustomAttribute", None)
+            if ca_table:
+                for ca in ca_table.rows:
+                    idx = ca.Parent.row_index
+                    if idx not in ca_map:
+                        ca_map[idx] = []
+                    ca_map[idx].append(ca)
 
-            for td in self.dotnetpe.net.mdtables.TypeDef.rows:
+            td_table = getattr(self.dotnetpe.net.mdtables, "TypeDef", None)
+            if not td_table:
+                return config
+
+            for td in td_table.rows:
                 if (
                     td.TypeNamespace.value != typespacename
                     and td.TypeName.value != typename
                 ):
                     continue
-                for pd_row_index, pd in enumerate(
-                    self.dotnetpe.net.mdtables.Property.rows
-                ):
+                prop_table = getattr(self.dotnetpe.net.mdtables, "Property", None)
+                if not prop_table:
+                    continue
+                for pd_row_index, pd in enumerate(prop_table.rows):
                     if pd.Name.value.startswith((
                         "Boolean_",
                         "BorderStyle_",