replace Nasm assembler with Keystone engine

README

@@ -17,6 +17,7 @@ writing custom interactive Python GDB commands.
     - GDB 7.x
     - Python 2.6+
     - Utilities: nasm, readelf, objdump
+    - Keystone engine as dependency (www.keystone-engine.org)
 
 3. Installation
     - Download

lib/config.py

@@ -16,7 +16,6 @@
 # external binaries, required for some commands
 READELF      = "/usr/bin/readelf"
 OBJDUMP      = "/usr/bin/objdump"
-NASM         = "/usr/bin/nasm"
 NDISASM      = "/usr/bin/ndisasm"
 
 # PEDA global options

lib/nasm.py

@@ -16,45 +16,11 @@
 
 class Nasm(object):
     """
-    Wrapper class for assemble/disassemble using nasm/ndisassm
+    Wrapper class for disassemble using ndisassm
     """
     def __init__(self):
         pass
 
-    @staticmethod
-    def assemble(asmcode, mode=32):
-        """
-        Assemble ASM instructions using NASM
-            - asmcode: input ASM instructions, multiple instructions are separated by ";" (String)
-            - mode: 16/32/64 bits assembly
-
-        Returns:
-            - bin code (raw bytes)
-        """
-        if not os.path.exists(config.NASM):
-            error_msg("%s binary not found, please install NASM for asm/rop functions" % config.NASM)
-            raise UserWarning("missing requirement")
-
-        asmcode = asmcode.strip('"').strip("'")
-        asmcode = asmcode.replace(";", "\n")
-        asmcode = ("BITS %d\n" % mode) + asmcode
-        asmcode = decode_string_escape(asmcode)
-        asmcode = re.sub("PTR|ptr|ds:|DS:", "", asmcode)
-        infd = tmpfile()
-        outfd = tmpfile(is_binary_file=True)
-        infd.write(asmcode)
-        infd.flush()
-        execute_external_command("%s -f bin -o %s %s" % (config.NASM, outfd.name, infd.name))
-        infd.close()
-
-        if os.path.exists(outfd.name):
-            bincode = outfd.read()
-            outfd.close()
-            return bincode
-        # reopen it so tempfile will not complain
-        open(outfd.name,'w').write('B00B')
-        return None
-
     @staticmethod
     def disassemble(buf, mode=32):
         """

peda.py

@@ -19,6 +19,8 @@
 import traceback
 import codecs
 
+from keystone import *
+
 # point to absolute path of peda.py
 PEDAFILE = os.path.abspath(os.path.expanduser(__file__))
 if os.path.islink(PEDAFILE):
@@ -754,7 +756,17 @@ def assemble(self, asmcode, bits=None):
         """
         if bits is None:
             (arch, bits) = self.getarch()
-        return Nasm.assemble(asmcode, bits)
+
+        if bits == 16:
+            mode = KS_MODE_16
+        if bits == 32:
+            mode = KS_MODE_32
+        if bits == 64:
+            mode = KS_MODE_64
+
+        ks = Ks(KS_ARCH_X86, mode)
+        encoding, count = ks.asm(asmcode)
+        return encoding
 
     def disassemble(self, *arg):
         """