[project @ Arch-1:robey@lag.net--2005-master-shake%paramiko--dev--1--patch-26]

new ssh agent support!  from john rochester.  added a bunch of docs to it, and changed demo.py to use an Agent if it finds a working key there.

1 files changed, 133 insertions, 0 deletions

diff --git a/paramiko/agent.py b/paramiko/agent.py
new file mode 100644
index 00000000..7e32c79d
--- /dev/null
+++ b/paramiko/agent.py
@@ -0,0 +1,133 @@
+# Copyright (C) 2003-2005 John Rochester <john@jrochester.org>
+#
+# This file is part of paramiko.
+#
+# Paramiko is free software; you can redistribute it and/or modify it under the
+# terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation; either version 2.1 of the License, or (at your option)
+# any later version.
+#
+# Paramiko is distrubuted in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
+# 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+
+"""
+SSH Agent interface for Unix clients.
+"""
+
+import os, socket, struct
+
+from ssh_exception import SSHException
+from message import Message
+from pkey import PKey
+
+SSH2_AGENTC_REQUEST_IDENTITIES, SSH2_AGENT_IDENTITIES_ANSWER, \
+    SSH2_AGENTC_SIGN_REQUEST, SSH2_AGENT_SIGN_RESPONSE = range(11, 15)
+
+class Agent:
+    """
+    Client interface for using private keys from an SSH agent running on the
+    local machine.  If an SSH agent is running, this class can be used to
+    connect to it and retreive L{PKey} objects which can be used when
+    attempting to authenticate to remote SSH servers.
+    
+    Because the SSH agent protocol uses environment variables and unix-domain
+    sockets, this probably doesn't work on Windows.  It does work on most
+    posix platforms though (Linux and MacOS X, for example).
+    """
+    
+    def __init__(self):
+        """
+        Open a session with the local machine's SSH agent, if one is running.
+        If no agent is running, initialization will succeed, but L{get_keys}
+        will return an empty tuple.
+        
+        @raise SSHException: if an SSH agent is found, but speaks an
+            incompatible protocol
+        """
+        if 'SSH_AUTH_SOCK' in os.environ:
+            conn = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+            conn.connect(os.environ['SSH_AUTH_SOCK'])
+            self.conn = conn
+            type, result = self._send_message(chr(SSH2_AGENTC_REQUEST_IDENTITIES))
+            if type != SSH2_AGENT_IDENTITIES_ANSWER:
+                raise SSHException('could not get keys from ssh-agent')
+            keys = []
+            for i in range(result.get_int()):
+                keys.append(AgentKey(self, result.get_string()))
+                result.get_string()
+            self.keys = tuple(keys)
+        else:
+            self.keys = ()
+
+    def close(self):
+        """
+        Close the SSH agent connection.
+        """
+        self.conn.close()
+        self.conn = None
+        self.keys = ()
+
+    def get_keys(self):
+        """
+        Return the list of keys available through the SSH agent, if any.  If
+        no SSH agent was running (or it couldn't be contacted), an empty list
+        will be returned.
+        
+        @return: a list of keys available on the SSH agent
+        @rtype: tuple of L{AgentKey}
+        """
+        return self.keys
+
+    def _send_message(self, msg):
+        msg = str(msg)
+        self.conn.send(struct.pack('>I', len(msg)) + msg)
+        l = self._read_all(4)
+        msg = Message(self._read_all(struct.unpack('>I', l)[0]))
+        return ord(msg.get_byte()), msg
+
+    def _read_all(self, wanted):
+        result = self.conn.recv(wanted)
+        while len(result) < wanted:
+            if len(result) == 0:
+                raise SSHException('lost ssh-agent')
+            extra = self.conn.recv(wanted - len(result))
+            if len(extra) == 0:
+                raise SSHException('lost ssh-agent')
+            result += extra
+        return result
+
+
+class AgentKey(PKey):
+    """
+    Private key held in a local SSH agent.  This type of key can be used for
+    authenticating to a remote server (signing).  Most other key operations
+    work as expected.
+    """
+    
+    def __init__(self, agent, blob):
+        self.agent = agent
+        self.blob = blob
+        self.name = Message(blob).get_string()
+
+    def __str__(self):
+        return self.blob
+
+    def get_name(self):
+        return self.name
+
+    def sign_ssh_data(self, randpool, data):
+        msg = Message()
+        msg.add_byte(chr(SSH2_AGENTC_SIGN_REQUEST))
+        msg.add_string(self.blob)
+        msg.add_string(data)
+        msg.add_int(0)
+        type, result = self.agent._send_message(msg)
+        if type != SSH2_AGENT_SIGN_RESPONSE:
+            raise SSHException('key cannot be used for signing')
+        return result.get_string()