symtbl: Overload __getitem__ for translating raw offsets

Can now use Symtbl subscript syntax to obtain the mapped address of a
foreign offset (not a defined symbol) without having to modify the
object or add a new symbol entry.

Assuming a base value of 10, tbl[15] will return 25, for example.

We now assert that the defined table keys are strings, to prevent the
creation of entries that are now un-readable by this patch.  However,
this always should have been the case.

Signed-off-by: Malfurious <m@lfurio.us>
Signed-off-by: dusoleil <howcansocksbereal@gmail.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/sploit/symtbl.py b/sploit/symtbl.py
index ce57277..3babd96 100644
--- a/sploit/symtbl.py
+++ b/sploit/symtbl.py
@@ -143,17 +143,20 @@ class SymtblImpl:
         return len(self.__entries__)
 
     def __getitem__(self, symbol):
-        """Return symbol offset or subtable via subscript"""
+        """Return symbol offset, subtable, or translated offset via subscript"""
         if symbol == "base":
             return self.base
-        return self.__entries__[symbol] + (self.base + self.__adjust__)
+        offset = symbol if type(symbol) is int else self.__entries__[symbol]
+        return offset + (self.base + self.__adjust__)
 
     def __setitem__(self, symbol, value):
         """Set symbol offset or subtable via subscript"""
         if symbol == "base":
             object.__setattr__(self, "base", int(value))
         elif symbol in dir(self):
-            raise KeyError(f"Symtbl: name '{symbol}' is reserved")
+            raise KeyError(f"Symtbl: key is reserved: {symbol}")
+        elif type(symbol) is not str:
+            raise KeyError(f"Symtbl: key must be a string: {symbol}")
         else:
             self.__entries__[symbol] = value - (self.base + self.__adjust__)