From 796ca3daf9c9fa4e2a10a6a9b50ca18eaf9656ac Mon Sep 17 00:00:00 2001
From: Philipp Maier <pmaier@sysmocom.de>
Date: Mon, 1 Nov 2021 17:13:57 +0100
Subject: [PATCH] commands: do not check SW manually, use send_apdu_checksw()

The transport layer provides a method send_apdu_checksw to send APDUs
and to be sure the SW is the expected one. Given that, there is no need
to verify the SW manually. The exception of send_apdu_checksw will catch
the problem and also display the SW in a human readable form.

Change-Id: I9ce556ac0b7bb21c5c5a27170c32af0152255b79
Related: OS#5275
---
 pySim/commands.py | 31 +++++++++++++++----------------
 pySim/utils.py    | 15 +++++++++++++++
 2 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/pySim/commands.py b/pySim/commands.py
index 805fe61f..1faa00ff 100644
--- a/pySim/commands.py
+++ b/pySim/commands.py
@@ -23,7 +23,7 @@
 
 from construct import *
 from pySim.construct import LV
-from pySim.utils import rpad, b2h, h2b, sw_match, bertlv_encode_len, Hexstr, h2i
+from pySim.utils import rpad, b2h, h2b, sw_match, bertlv_encode_len, Hexstr, h2i, str_sanitize
 from pySim.exceptions import SwMatchError
 
 class SimCardCommands(object):
@@ -145,12 +145,12 @@ class SimCardCommands(object):
 		while chunk_offset < length:
 			chunk_len = min(255, length-chunk_offset)
 			pdu = self.cla_byte + 'b0%04x%02x' % (offset + chunk_offset, chunk_len)
-			data,sw = self._tp.send_apdu(pdu)
-			if sw == '9000':
-				total_data += data
-				chunk_offset += chunk_len
-			else:
-				raise ValueError('Failed to read (offset %d)' % (offset))
+			try:
+				data, sw = self._tp.send_apdu_checksw(pdu)
+			except Exception as e:
+				raise ValueError('%s, failed to read (offset %d)' % (str_sanitize(str(e)), offset))
+			total_data += data
+			chunk_offset += chunk_len
 		return total_data, sw
 
 	def update_binary(self, ef, data:str, offset:int=0, verify:bool=False, conserve:bool=False):
@@ -172,22 +172,21 @@ class SimCardCommands(object):
 
 		self.select_path(ef)
 		total_data = ''
-		total_sw = "9000"
 		chunk_offset = 0
 		while chunk_offset < data_length:
 			chunk_len = min(255, data_length - chunk_offset)
 			# chunk_offset is bytes, but data slicing is hex chars, so we need to multiply by 2
 			pdu = self.cla_byte + 'd6%04x%02x' % (offset + chunk_offset, chunk_len) + data[chunk_offset*2 : (chunk_offset+chunk_len)*2]
-			chunk_data, chunk_sw = self._tp.send_apdu(pdu)
-			if chunk_sw == total_sw:
-				total_data += chunk_data
-				chunk_offset += chunk_len
-			else:
-				total_sw = chunk_sw
-				raise ValueError('Failed to write chunk (chunk_offset %d, chunk_len %d)' % (chunk_offset, chunk_len))
+			try:
+				chunk_data, chunk_sw = self._tp.send_apdu_checksw(pdu)
+			except Exception as e:
+				raise ValueError('%s, failed to write chunk (chunk_offset %d, chunk_len %d)' % \
+						 (str_sanitize(str(e)), chunk_offset, chunk_len))
+			total_data += data
+			chunk_offset += chunk_len
 		if verify:
 			self.verify_binary(ef, data, offset)
-		return total_data, total_sw
+		return total_data, chunk_sw
 
 	def verify_binary(self, ef, data:str, offset:int=0):
 		"""Verify contents of transparent EF.
diff --git a/pySim/utils.py b/pySim/utils.py
index 68de14ae..8f2b2e90 100644
--- a/pySim/utils.py
+++ b/pySim/utils.py
@@ -5,6 +5,7 @@
 
 import json
 import abc
+import string
 from io import BytesIO
 from typing import Optional, List, Dict, Any, Tuple
 
@@ -89,6 +90,20 @@ def lpad(s:str, l:int, c='f') -> str:
 def half_round_up(n:int) -> int:
 	return (n + 1)//2
 
+def str_sanitize(s:str) -> str:
+	"""replace all non printable chars, line breaks and whitespaces, with ' ', make sure that
+	there are no whitespaces at the end and at the beginning of the string.
+
+	Args:
+		s : string to sanitize
+	Returns:
+		filtered result of string 's'
+	"""
+
+	chars_to_keep = string.digits + string.ascii_letters + string.punctuation
+	res = ''.join([c if c in chars_to_keep else ' ' for c in s])
+	return res.strip()
+
 #########################################################################
 # poor man's COMPREHENSION-TLV decoder.
 #########################################################################