Load key files manually before making SSH connections

Change-Id: I63828b940d9bedcfff854f6732a78c09828666af

tobiko/shell/ssh/_client.py

@@ -18,8 +18,8 @@ from __future__ import absolute_import
 import collections
 import contextlib
 import getpass
+import io
 import os
-import socket
 import subprocess
 import time
 import threading
@@ -579,6 +579,21 @@ def ssh_client(host, port=None, username=None, proxy_jump=None,
                               **connect_parameters)
 
 
+def load_private_keys(key_filenames: typing.List[str]):
+    pkeys = []
+    for filename in key_filenames:
+        if os.path.exists(filename):
+            try:
+                with io.open(filename, 'rt') as fd:
+                    pkey = paramiko.RSAKey.from_private_key(fd)
+            except Exception:
+                LOG.error('Unable to get RSAKey private key from file: '
+                          f'{filename}', exc_info=1)
+            else:
+                pkeys.append(pkey)
+    return pkeys
+
+
 def ssh_connect(hostname, username=None, port=None, connection_interval=None,
                 connection_attempts=None, connection_timeout=None,
                 proxy_command=None, proxy_client=None, key_filename=None,
@@ -587,13 +602,9 @@ def ssh_connect(hostname, username=None, port=None, connection_interval=None,
     client.set_missing_host_key_policy(paramiko.WarningPolicy())
     login = _command.ssh_login(hostname=hostname, username=username, port=port)
 
-    if key_filename:
+    assert isinstance(key_filename, list)
-        # Ensures we try enough times to try all keys
+    pkeys = load_private_keys(key_filename)
-        tobiko.check_valid_type(key_filename, list)
+    auth_failed: typing.Optional[Exception] = None
-        connection_attempts = max(connection_attempts or 1,
-                                  len(key_filename),
-                                  1)
-
     for attempt in tobiko.retry(count=connection_attempts,
                                 timeout=connection_timeout,
                                 interval=connection_interval,
@@ -603,8 +614,8 @@ def ssh_connect(hostname, username=None, port=None, connection_interval=None,
         LOG.debug(f"Logging in to '{login}'...\n"
                   f"  - parameters: {parameters}\n"
                   f"  - attempt: {attempt.details}\n")
-
+        for pkey in pkeys + [None]:
-        try:
+            succeeded = False
             proxy_sock = ssh_proxy_sock(
                 hostname=hostname,
                 port=port,
@@ -613,29 +624,35 @@ def ssh_connect(hostname, username=None, port=None, connection_interval=None,
                 timeout=connection_timeout,
                 connection_attempts=1,
                 connection_interval=connection_interval)
-            client.connect(hostname=hostname,
+            try:
-                           username=username,
+                client.connect(hostname=hostname,
-                           port=port,
+                               username=username,
-                           sock=proxy_sock,
+                               port=port,
-                           key_filename=key_filename,
+                               sock=proxy_sock,
-                           **parameters)
+                               pkey=pkey,
-        except ValueError as ex:
+                               **parameters)
-            attempt.check_limits()
+            except paramiko.ssh_exception.AuthenticationException as ex:
-            if (str(ex) == 'q must be exactly 160, 224, or 256 bits long' and
+                if auth_failed is not None:
-                    len(key_filename) > 1):
+                    ex.__cause__ = auth_failed
-                # Must try without the first key
+                auth_failed = ex
-                LOG.debug(f"Retry connecting with the next key: {ex}")
-                key_filename = key_filename[1:]
                 continue
+            except Exception as ex:
+                LOG.debug(f"Error logging in to '{login}': {ex}", exc_info=1)
+                attempt.check_limits()
+                break
             else:
-                raise
+                LOG.debug(f"Successfully logged in to '{login}'")
-        except (EOFError, socket.error, socket.timeout,
+                succeeded = True
-                paramiko.SSHException) as ex:
+                return client, proxy_sock
-            attempt.check_limits()
+            finally:
-            LOG.debug(f"Error logging in to '{login}': {ex}")
+                if not succeeded:
+                    try:
+                        proxy_sock.close()
+                    except Exception:
+                        pass
         else:
-            LOG.debug(f"Successfully logged in to '{login}'")
+            if isinstance(auth_failed, Exception):
-            return client, proxy_sock
+                raise auth_failed
 
 
 def ssh_proxy_sock(hostname=None, port=None, command=None, client=None,