Allow any buffer type to be sent to Channel

Fixes #968

Changes the behaviour of the underlying asbytes helper to
pass along unknown types. Most callers already handle this
by passing the bytes along to a file or socket-like object
which will raise TypeError anyway.

Adds test coverage through the Transport implementation.

Change against the 1.17 branch.

1 files changed, 10 insertions, 9 deletions

diff --git a/paramiko/common.py b/paramiko/common.py
index 556f046a..3b18858b 100644
--- a/paramiko/common.py
+++ b/paramiko/common.py
@@ -21,7 +21,7 @@ Common constants and global variables.
 """
 import logging
 from paramiko.py3compat import (
-    byte_chr, PY2, bytes_types, string_types, b, long,
+    byte_chr, PY2, bytes_types, text_type, string_types, b, long,
 )
 
 MSG_DISCONNECT, MSG_IGNORE, MSG_UNIMPLEMENTED, MSG_DEBUG, \
@@ -163,14 +163,15 @@ else:
 
 
 def asbytes(s):
-    if not isinstance(s, bytes_types):
-        if isinstance(s, string_types):
-            s = b(s)
-        else:
-            try:
-                s = s.asbytes()
-            except Exception:
-                raise Exception('Unknown type')
+    if isinstance(s, bytes_types):
+        return s
+    if isinstance(s, text_type):
+        # GZ 2017-05-25: Accept text and encode as utf-8 for compatibilty only.
+        return s.encode("utf-8")
+    asbytes = getattr(s, "asbytes", None)
+    if asbytes is not None:
+        return asbytes()
+    # May be an object that implements the buffer api, let callers decide
     return s