utils: Add binary_str() method to print binary data

Because repr() is not enough to escape ascii code or control code,
MsgBase.__str__() may collapse representation with binary data.
This patch add binary_str() in order to convert binary data into a
sequence of '\x00' style string.

Signed-off-by: IWASE Yusuke <iwase.yusuke0@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

ryu/tests/unit/test_utils.py

@@ -15,6 +15,7 @@
 
 import unittest
 import logging
+import six
 from nose.tools import eq_
 
 from ryu import utils
@@ -55,3 +56,29 @@ class Test_utils(unittest.TestCase):
         expected_result = '0x01 0x02 0x03 0x04'
         data = bytes(b'\x01\x02\x03\x04')
         eq_(expected_result, utils.hex_array(data))
+
+    def test_binary_str_string(self):
+        """
+        Test binary_str() with str type.
+        """
+        expected_result = '\\x01\\x02\\x03\\x04'
+        data = b'\x01\x02\x03\x04'
+        eq_(expected_result, utils.binary_str(data))
+
+    def test_binary_str_bytearray(self):
+        """
+        Test binary_str() with bytearray type.
+        """
+        expected_result = '\\x01\\x02\\x03\\x04'
+        data = bytearray(b'\x01\x02\x03\x04')
+        eq_(expected_result, utils.binary_str(data))
+
+    def test_binary_str_bytes(self):
+        """
+        Test binary_str() with bytes type. (Python3 only)
+        """
+        if six.PY2:
+            return
+        expected_result = '\\x01\\x02\\x03\\x04'
+        data = bytes(b'\x01\x02\x03\x04')
+        eq_(expected_result, utils.binary_str(data))

ryu/utils.py

@@ -106,6 +106,14 @@ def hex_array(data):
     return ' '.join('0x%02x' % byte for byte in bytearray(data))
 
 
+def binary_str(data):
+    """
+    Convert six.binary_type or bytearray into str to be printed.
+    """
+    # convert data into bytearray explicitly
+    return ''.join('\\x%02x' % byte for byte in bytearray(data))
+
+
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