Merge python#13

13: warn for hmac and hexlify r=ltratt a=nanjekyejoannah

This PR adds warnings for the following modules:
- `hmac`
- `binascii.hexlify`
- `binascii.b2a_hex`

See the notes below:

1. warn for the 'digest' parameter in hmac in pygrate2

In Python 2:

```
>>> import hashlib
>>> import hmac
>>> string1 = 'firststring'.encode('utf-8')
>>> string2 = 'secondstring'.encode('utf-8')
>>> digest = hmac.new(key=string1, msg=string2, digestmod=hashlib.sha256).digest()
>>> digest = hmac.new(key=string1, msg=string2).digest() 
>>> 
```

In Python 3:

```
string1 = 'firststring'.encode('utf-8')
>>> string2 = 'secondstring'.encode('utf-8')
>>> digest = hmac.new(key=string1, msg=string2, digestmod=hashlib.sha256).digest()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'hmac' is not defined
>>> import hashlib
>>> import hmac
>>> digest = hmac.new(key=string1, msg=string2, digestmod=hashlib.sha256).digest()
>>> digest = hmac.new(key=string1, msg=string2).digest() 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/Cellar/python@3.9/3.9.12_1/Frameworks/Python.framework/Versions/3.9/lib/python3.9/hmac.py", line 170, in new
    return HMAC(key, msg, digestmod)
  File "/usr/local/Cellar/python@3.9/3.9.12_1/Frameworks/Python.framework/Versions/3.9/lib/python3.9/hmac.py", line 56, in __init__
    raise TypeError("Missing required parameter 'digestmod'.")
TypeError: Missing required parameter 'digestmod'.
>>> 
```


2. Warn for hexlify 

In python 2:

```
>>> import codecs
>>> hexlify = codecs.getencoder('hex')
>>> hexlify(b'Blaah')[0]
'426c616168'
>>> import binascii
>>> binascii.hexlify(b'Blaah')
'426c616168'
>>> binascii.hexlify('Blaah')
'426c616168'
>>> 
```

In Python 3:

```
>>> import codecs
>>> hexlify = codecs.getencoder('hex')
>>> hexlify(b'Blaah')[0]
b'426c616168'
>>> import binascii
>>> binascii.hexlify(b'Blaah')
b'426c616168'
>>> binascii.hexlify('Blaah')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: a bytes-like object is required, not 'str'
>>> 
```


Co-authored-by: Joannah Nanjekye <jnanjekye@python.org>

Author: bors[bot]

Lib/hmac.py

@@ -4,6 +4,8 @@
 """
 
 import warnings as _warnings
+import sys
+
 
 from operator import _compare_digest as compare_digest
 
@@ -41,6 +43,10 @@ def __init__(self, key, msg = None, digestmod = None):
             return
 
         if digestmod is None:
+            if sys.py3kwarning:
+                _warnings.warnpy3k_with_fix('the digestmod paramemer is required in 3.x', 
+                                  'generate a digest with hashlib module',
+                                  DeprecationWarning, stacklevel=4)
             import hashlib
             digestmod = hashlib.md5
 

Lib/test/test_binascii.py

@@ -172,8 +172,11 @@ def test_hex(self):
         self.assertRaises(TypeError, binascii.a2b_hex, t[:-1] + 'q')
 
         # Verify the treatment of Unicode strings
-        if test_support.have_unicode:
-            self.assertEqual(binascii.hexlify(unicode('a', 'ascii')), '61')
+        with test_support.check_py3k_warnings(("The hexlify() module expects bytes in 3.x; use the 'b' prefix on the string",
+                                  DeprecationWarning)):
+            if test_support.have_unicode:
+                self.assertEqual(binascii.hexlify(unicode('a', 'ascii')), '61')
+                self.assertEqual(binascii.b2a_hex(unicode('a', 'ascii')), '61')
 
     def test_qp(self):
         type2test = self.type2test

Lib/test/test_hmac.py

@@ -12,37 +12,37 @@ def test_md5_vectors(self):
         # Test the HMAC module against test vectors from the RFC.
 
         def md5test(key, data, digest):
-            h = hmac.HMAC(key, data)
+            h = hmac.HMAC(key, data, digestmod=hashlib.sha1)
             self.assertEqual(h.hexdigest().upper(), digest.upper())
 
         md5test(chr(0x0b) * 16,
                 "Hi There",
-                "9294727A3638BB1C13F48EF8158BFC9D")
+                "675B0B3A1B4DDF4E124872DA6C2F632BFED957E9")
 
         md5test("Jefe",
                 "what do ya want for nothing?",
-                "750c783e6ab0b503eaa86e310a5db738")
+                "EFFCDF6AE5EB2FA2D27416D5F184DF9C259A7C79")
 
         md5test(chr(0xAA)*16,
                 chr(0xDD)*50,
-                "56be34521d144c88dbb8c733f0e8b3f6")
+                "D730594D167E35D5956FD8003D0DB3D3F46DC7BB")
 
         md5test("".join([chr(i) for i in range(1, 26)]),
                 chr(0xCD) * 50,
-                "697eaf0aca3a3aea3a75164746ffaa79")
+                "4C9007F4026250C6BC8414F9BF50C86C2D7235DA")
 
         md5test(chr(0x0C) * 16,
                 "Test With Truncation",
-                "56461ef2342edc00f9bab995690efd4c")
+                "37268B7E21E84DA5720C53C4BA03AD1104039FA7")
 
         md5test(chr(0xAA) * 80,
                 "Test Using Larger Than Block-Size Key - Hash Key First",
-                "6b1ab7fe4bd7bf8f0b62e6ce61b9d0cd")
+                "AA4AE5E15272D00E95705637CE8A3B55ED402112")
 
         md5test(chr(0xAA) * 80,
                 ("Test Using Larger Than Block-Size Key "
                  "and Larger Than One Block-Size Data"),
-                "6f630fad67cda0ee1fb1f562db3aa53e")
+                "E8E99D0F45237D786D6BBAA7965C7808BBFF1A91")
 
     def test_sha_vectors(self):
         def shatest(key, data, digest):
@@ -232,14 +232,14 @@ def test_normal(self):
         # Standard constructor call.
         failed = 0
         try:
-            h = hmac.HMAC("key")
+            h = hmac.HMAC("key", digestmod=hashlib.sha1)
         except:
             self.fail("Standard constructor call raised exception.")
 
     def test_withtext(self):
         # Constructor call with text.
         try:
-            h = hmac.HMAC("key", "hash this!")
+            h = hmac.HMAC("key", "hash this!", digestmod=hashlib.sha1)
         except:
             self.fail("Constructor call with text argument raised exception.")
 
@@ -250,6 +250,11 @@ def test_withmodule(self):
         except:
             self.fail("Constructor call with hashlib.sha1 raised exception.")
 
+    def test_3k_no_digest(self):
+        with test_support.check_py3k_warnings(("the digestmod paramemer is required in 3.x; generate a digest with hashlib module",
+                                  DeprecationWarning)):
+            h = hmac.HMAC("key", "", hashlib.sha1)
+
 class SanityTestCase(unittest.TestCase):
 
     def test_default_is_md5(self):
@@ -262,7 +267,7 @@ def test_exercise_all_methods(self):
         # Exercising all methods once.
         # This must not raise any exceptions
         try:
-            h = hmac.HMAC("my secret key")
+            h = hmac.HMAC("my secret key", digestmod=hashlib.sha1)
             h.update("compute the hash of this text!")
             dig = h.digest()
             dig = h.hexdigest()
@@ -274,7 +279,7 @@ class CopyTestCase(unittest.TestCase):
 
     def test_attributes(self):
         # Testing if attributes are of same type.
-        h1 = hmac.HMAC("key")
+        h1 = hmac.HMAC("key", digestmod=hashlib.sha1)
         h2 = h1.copy()
         self.assertTrue(h1.digest_cons == h2.digest_cons,
             "digest constructors don't match.")
@@ -285,7 +290,7 @@ def test_attributes(self):
 
     def test_realcopy(self):
         # Testing if the copy method created a real copy.
-        h1 = hmac.HMAC("key")
+        h1 = hmac.HMAC("key", digestmod=hashlib.sha1)
         h2 = h1.copy()
         # Using id() in case somebody has overridden __cmp__.
         self.assertTrue(id(h1) != id(h2), "No real copy of the HMAC instance.")
@@ -296,7 +301,7 @@ def test_realcopy(self):
 
     def test_equality(self):
         # Testing if the copy has the same digests.
-        h1 = hmac.HMAC("key")
+        h1 = hmac.HMAC("key", digestmod=hashlib.sha1)
         h1.update("some random text")
         h2 = h1.copy()
         self.assertTrue(h1.digest() == h2.digest(),

Lib/warnings.py

@@ -23,6 +23,16 @@ def warnpy3k(message, category=None, stacklevel=1):
             category = DeprecationWarning
         warn(message, category, stacklevel+1)
 
+def warnpy3k_with_fix(message, category=None, stacklevel=1):
+    """Issue a deprecation warning for Python 3.x related changes and a fix.
+
+    Warnings are omitted unless Python is started with the -3 option.
+    """
+    if sys.py3kwarning:
+        if category is None:
+            category = DeprecationWarning
+        warn_with_fix(message, fix, category, stacklevel+1)
+
 def _show_warning(message, category, filename, lineno, file=None, line=None):
     """Hook to write a warning to a file; replace if you like."""
     if file is None:
@@ -343,6 +353,46 @@ def warn_explicit(message, category, filename, lineno,
     # Print message and context
     showwarning(message, category, filename, lineno)
 
+def warn_with_fix(message, fix, category=None, stacklevel=1):
+    """Issue a warning, or maybe ignore it or raise an exception."""
+    # Check if message is already a Warning object
+    if isinstance(message, Warning):
+        category = message.__class__
+    # Check category argument
+    if category is None:
+        category = UserWarning
+    assert issubclass(category, Warning)
+    # Get context information
+    try:
+        caller = sys._getframe(stacklevel)
+    except ValueError:
+        globals = sys.__dict__
+        lineno = 1
+    else:
+        globals = caller.f_globals
+        lineno = caller.f_lineno
+    if '__name__' in globals:
+        module = globals['__name__']
+    else:
+        module = "<string>"
+    filename = globals.get('__file__')
+    if filename:
+        fnl = filename.lower()
+        if fnl.endswith((".pyc", ".pyo")):
+            filename = filename[:-1]
+    else:
+        if module == "__main__":
+            try:
+                filename = sys.argv[0]
+            except AttributeError:
+                # embedded interpreters don't have sys.argv, see bug #839151
+                filename = '__main__'
+        if not filename:
+            filename = module
+    registry = globals.setdefault("__warningregistry__", {})
+    warn_explicit_with_fix(message, fix, category, filename, lineno, module, registry,
+                  globals)
+
 def warn_explicit_with_fix(message, fix, category, filename, lineno,
                   module=None, registry=None, module_globals=None):
     lineno = int(lineno)

Modules/binascii.c

@@ -1051,6 +1051,11 @@ binascii_hexlify(PyObject *self, PyObject *args)
     argbuf = parg.buf;
     arglen = parg.len;
 
+    if (PyUnicode_Check(args))
+        if (PyErr_WarnPy3k_WithFix("The hexlify() module expects bytes in 3.x",
+                                   "use the 'b' prefix on the string", 1) < 0)
+            return NULL;
+
     assert(arglen >= 0);
     if (arglen > PY_SSIZE_T_MAX / 2) {
         PyBuffer_Release(&parg);