Add solve_buffer to API (#280)

* add solve_buffer to api and update google ctf script to use it

* start adding push/pop_constraints functionality

* remove push/pop constraints, just use with

* add mark's changes

* add solve_buffer to api.rst

* fix typo

docs/api.rst

@@ -20,7 +20,7 @@ State
 -----
 
 .. autoclass:: manticore.core.state.State
-   :members: abandon, constrain, new_symbolic_buffer, new_symbolic_value, solve_n, solve_one, symbolicate_buffer, invoke_model
+   :members: abandon, constrain, new_symbolic_buffer, new_symbolic_value, solve_n, solve_one, solve_buffer, symbolicate_buffer, invoke_model
 
 Cpu
 ---

manticore/core/state.py

@@ -232,6 +232,24 @@ class State(object):
         '''
         return self._solver.get_all_values(self.constraints, expr, nsolves, silent=True)
 
+    def solve_buffer(self, addr, nbytes):
+        '''
+        Reads `nbytes` of symbolic data from a buffer in memory at `addr` and attempts to
+        concretize it
+
+        :param int address: Address of buffer to concretize
+        :param int nbytes: Size of buffer to concretize
+        :return: Concrete contents of buffer
+        :rtype: list[int]
+        '''
+        buffer = self.cpu.read_bytes(addr, nbytes)
+        result = []
+        with self.constraints as temp_cs:
+            for c in buffer:
+                result.append(self._solver.get_value(temp_cs, c))
+                temp_cs.add(c == result[-1])
+        return result
+
     def record_branches(self, targets):
         _, branch = self.last_pc
         for target in targets: