Initial port of ProxyCommand class from @clarete

paramiko/proxy.py

@@ -0,0 +1,86 @@
+# Copyright (C) 2012  Yipit, Inc <coders@yipit.com>
+#
+# This file is part of ssh.
+#
+# 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.
+#
+# 'ssh' 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 'ssh'; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Suite 500, Boston, MA  02110-1335  USA.
+
+import os
+from shlex import split as shlsplit
+from subprocess import Popen, PIPE
+
+from ssh.ssh_exception import BadProxyCommand
+
+
+class ProxyCommand(object):
+    """
+    A proxy based on the program informed in the ProxyCommand config.
+
+    This class implements a the interface needed by both L{Transport}
+    and L{Packetizer} classes. Using this class instead of a regular
+    socket makes it possible to talk with a popened command that will
+    proxy all the conversation between the client and a server hosted in
+    another machine.
+    """
+
+    def __init__(self, command_line):
+        """
+        Create a new CommandProxy instance. The instance created by this
+        class should be passed as argument to the L{Transport} class.
+
+        @param command_line: the command that should be executed and
+         used as the proxy.
+        @type command_line: str
+        """
+        self.cmd = shlsplit(command_line)
+        self.process = Popen(self.cmd, stdin=PIPE, stdout=PIPE, stderr=PIPE)
+
+    def send(self, content):
+        """
+        Write the content received from the SSH client to the standard
+        input of the forked command.
+
+        @param content: string to be sent to the forked command
+        @type content: str
+        """
+        try:
+            self.process.stdin.write(content)
+        except IOError, exc:
+            # There was a problem with the child process. It probably
+            # died and we can't proceed. The best option here is to
+            # raise an exception informing the user that the informed
+            # ProxyCommand is not working.
+            raise BadProxyCommand(' '.join(self.cmd), exc.strerror)
+        return len(content)
+
+    def recv(self, size):
+        """
+        Read from the standard output of the forked program
+
+        @param size: how many chars should be read
+        @type size: int
+
+        @return: the length of the readed content
+        @rtype: int
+        """
+        try:
+            return os.read(self.process.stdout.fileno(), size)
+        except IOError, exc:
+            raise BadProxyCommand(' '.join(self.cmd), exc.strerror)
+
+    def close(self):
+        self.process.terminate()
+
+    def settimeout(self, timeout):
+        pass