Add a method to construct OID from integers

Author: sigmaris

gssapi/raw/oids.pyx

@@ -1,5 +1,7 @@
 GSSAPI="BASE"  # This ensures that a full module is generated by Cython
 
+import six
+
 from libc.string cimport memcmp, memcpy
 from libc.stdlib cimport free, malloc
 
@@ -51,6 +53,27 @@ cdef class OID:
         memcpy(self.raw_oid.elements, byte_str, self.raw_oid.length)
         return 0
 
+    @classmethod
+    def from_int_seq(cls, integer_sequence):
+        elements=cls._encode_asn1ber(integer_sequence)
+        return cls(elements=elements)
+
+    @staticmethod
+    def _encode_asn1ber(oid_seq):
+        if isinstance(oid_seq, six.string_types):
+            oid_seq = oid_seq.split('.')
+        oid_seq = [int(x) for x in oid_seq]
+        if len(oid_seq) < 2:
+            raise ValueError("Sequence must be 2 or more elements long.")
+        byte_seq = bytearray([oid_seq[0] * 40 + oid_seq[1]])
+        for element in oid_seq[2:]:
+            element_seq = [element & 0x7f]
+            while element > 127:
+                element >>= 7
+                element_seq.insert(0, (element & 0x7f) | 0x80)
+            byte_seq.extend(element_seq)
+        return bytes(byte_seq)
+
     def __dealloc__(self):
         # NB(directxman12): MIT Kerberos has gss_release_oid
         #                   for this purpose, but it's not in the RFC

setup.py

@@ -187,7 +187,8 @@ def gssapi_modules(lst):
     keywords=['gssapi', 'security'],
     install_requires=[
         'enum34',
-        'decorator'
+        'decorator',
+        'six'
     ],
     tests_require=[
         'tox'