scp: simplify SSH connection settings

The `allow_agent` setting was used with NC but not with SCP. Store it in
the device and reuse it for SCP.

The private key was stored in a dictionnary, but this is not needed as
Paramiko's `connect()` would default to `None` when not provided.

Grab the SSH key filename from SSH configuration as Paramiko won't do it
for us. For this reason, this commit is a followup to the one in Juniper#648.

lib/jnpr/junos/device.py

@@ -819,6 +819,7 @@ def __init__(self, *vargs, **kvargs):
             self._hostname = 'localhost'
             self._ssh_private_key_file = None
             self._ssh_config = None
+            self._allow_agent = False
         else:
             # --------------------------
             # making a remote connection
@@ -838,6 +839,12 @@ def __init__(self, *vargs, **kvargs):
             self._ssh_private_key_file = kvargs.get('ssh_private_key_file')
             self._auth_password = kvargs.get(
                 'password') or kvargs.get('passwd')
+            # we want to enable the ssh-agent if-and-only-if we are
+            # not given a password or an ssh key file.
+            # in this condition it means we want to query the agent
+            # for available ssh keys
+            self._allow_agent = bool((self._auth_password is None) and
+                                     (self._ssh_private_key_file is None))
 
         # -----------------------------
         # initialize instance variables
@@ -904,14 +911,6 @@ def open(self, *vargs, **kvargs):
         try:
             ts_start = datetime.datetime.now()
 
-            # we want to enable the ssh-agent if-and-only-if we are
-            # not given a password or an ssh key file.
-            # in this condition it means we want to query the agent
-            # for available ssh keys
-
-            allow_agent = bool((self._auth_password is None) and
-                               (self._ssh_private_key_file is None))
-
             # open connection using ncclient transport
             self._conn = netconf_ssh.connect(
                 host=self._hostname,
@@ -920,7 +919,7 @@ def open(self, *vargs, **kvargs):
                 password=self._auth_password,
                 hostkey_verify=False,
                 key_filename=self._ssh_private_key_file,
-                allow_agent=allow_agent,
+                allow_agent=self._allow_agent,
                 ssh_config=self._sshconf_lkup(),
                 device_params={'name': 'junos', 'local': False})
 

lib/jnpr/junos/utils/scp.py

@@ -88,29 +88,26 @@ def open(self, **scpargs):
         # use junos._hostname since this will be correct if we are going
         # through a jumphost.
 
-        config = {}
-        kwargs = {}
-        ssh_config = getattr(junos, '_sshconf_path')
+        # Retrieve ProxyCommand and IdentityFile
+        sock = None
+        key_file = junos._ssh_private_key_file
+        ssh_config = junos._sshconf_path
         if ssh_config:
             config = paramiko.SSHConfig()
             config.parse(open(ssh_config))
             config = config.lookup(junos._hostname)
-        sock = None
-        if config.get("proxycommand"):
-            sock = paramiko.proxy.ProxyCommand(config.get("proxycommand"))
-
-        if self._junos._ssh_private_key_file is not None:
-            kwargs['key_filename']=self._junos._ssh_private_key_file
+            if config.get("proxycommand"):
+                sock = paramiko.proxy.ProxyCommand(config.get("proxycommand"))
+            key_file = key_file or config.get("identityfile")
 
         self._ssh.connect(hostname=junos._hostname,
-                          port=(
-                              22, int(
-                                  junos._port))[
+                          port=(22, int(junos._port))[
                               junos._hostname == 'localhost'],
                           username=junos._auth_user,
                           password=junos._auth_password,
-                          sock=sock, **kwargs
-                          )
+                          key_filename=key_file,
+                          allow_agent=junos._allow_agent,
+                          sock=sock)
         return SCPClient(self._ssh.get_transport(), **scpargs)
 
     def close(self):