add line separator support

dkim/tests/test_dkim.py

@@ -46,6 +46,11 @@ class TestFold(unittest.TestCase):
         self.assertEqual(
             b"foo" * 24 + b"\r\n foo", dkim.fold(b"foo" * 25))
 
+    def test_linesep(self):
+        self.assertEqual(
+            b"foo" * 24 + b"\n foo", dkim.fold(b"foo" * 25, linesep=b"\n"))
+
+
 
 class TestSignAndVerify(unittest.TestCase):
     """End-to-end signature and verification tests."""
@@ -203,6 +208,17 @@ p=11qYAYKxCrfVS/7TyWQHOg7hcvPapiMlrwIaaPcHURo="""
                 res = d.verify(dnsfunc=self.dnsfunc5)
                 self.assertTrue(res)
 
+    def test_verifies_lflinesep(self):
+        # A message verifies after being signed.
+        for header_algo in (b"simple", b"relaxed"):
+            for body_algo in (b"simple", b"relaxed"):
+                sig = dkim.sign(
+                    self.message, b"test", b"example.com", self.key,
+                    canonicalize=(header_algo, body_algo), linesep=b"\n")
+                res = dkim.verify(sig + self.message, dnsfunc=self.dnsfunc)
+                self.assertFalse(b'\r\n' in sig)
+                self.assertTrue(res)
+
     def test_implicit_k(self):
         # A message verifies after being signed when k= tag is not provided.
         for header_algo in (b"simple", b"relaxed"):

dkim/tests/test_util.py

@@ -22,6 +22,7 @@ from dkim.util import (
     DuplicateTag,
     InvalidTagSpec,
     parse_tag_value,
+    get_linesep,
     )
 
 
@@ -75,6 +76,30 @@ class TestParseTagValue(unittest.TestCase):
       self.assertEqual(len(sig),11)
 
 
+class TestGetLineSep(unittest.TestCase):
+    """Line seperator probing tests."""
+
+    def test_default(self):
+        self.assertEqual(
+            b'\r\n',
+            get_linesep(b'abc'))
+
+    def test_withcrlf(self):
+        self.assertEqual(
+            b'\r\n',
+            get_linesep(b'abc\r\n'))
+
+    def test_withlf(self):
+        self.assertEqual(
+            b'\n',
+            get_linesep(b'abc\n'))
+
+    def test_toosmall(self):
+        self.assertEqual(
+            b'\r\n',
+            get_linesep(b'a'))
+
+
 def test_suite():
     from unittest import TestLoader
     return TestLoader().loadTestsFromName(__name__)