1 files changed, 95 insertions, 0 deletions
diff --git a/planetlab/pssh/psshlib/askpass_client.py b/planetlab/pssh/psshlib/askpass_client.py
new file mode 100644
index 0000000..fa4d40a
--- /dev/null
+++ b/planetlab/pssh/psshlib/askpass_client.py
@@ -0,0 +1,95 @@
+#!/usr/bin/env python
+# -*- Mode: python -*-
+
+# Copyright (c) 2009, Andrew McNabb
+
+"""Implementation of SSH_ASKPASS to get a password to ssh from pssh.
+
+The password is read from the socket specified by the environment variable
+PSSH_ASKPASS_SOCKET.  The other end of this socket is pssh.
+
+The ssh man page discusses SSH_ASKPASS as follows:
+    If ssh needs a passphrase, it will read the passphrase from the current
+    terminal if it was run from a terminal.  If ssh does not have a terminal
+    associated with it but DISPLAY and SSH_ASKPASS are set, it will execute
+    the program specified by SSH_ASKPASS and open an X11 window to read the
+    passphrase.  This is particularly useful when calling ssh from a .xsession
+    or related script.  (Note that on some machines it may be necessary to
+    redirect the input from /dev/null to make this work.)
+"""
+
+import os
+import socket
+import sys
+import textwrap
+
+bin_dir = os.path.dirname(os.path.abspath(sys.argv[0]))
+askpass_bin_path = os.path.join(bin_dir, 'pssh-askpass')
+ASKPASS_PATHS = (askpass_bin_path,
+        '/usr/libexec/pssh/pssh-askpass',
+        '/usr/local/libexec/pssh/pssh-askpass',
+        '/usr/lib/pssh/pssh-askpass',
+        '/usr/local/lib/pssh/pssh-askpass')
+
+_executable_path = None
+
+def executable_path():
+    """Determines the value to use for SSH_ASKPASS.
+
+    The value is cached since this may be called many times.
+    """
+    global _executable_path
+    if _executable_path is None:
+        for path in ASKPASS_PATHS:
+            if os.access(path, os.X_OK):
+                _executable_path = path
+                break
+        else:
+            _executable_path = ''
+            sys.stderr.write(textwrap.fill("Warning: could not find an"
+                    " executable path for askpass because PSSH was not"
+                    " installed correctly.  Password prompts will not work."))
+            sys.stderr.write('\n')
+    return _executable_path
+
+def askpass_main():
+    """Connects to pssh over the socket specified at PSSH_ASKPASS_SOCKET."""
+
+    # It's not documented anywhere, as far as I can tell, but ssh may prompt
+    # for a password or ask a yes/no question.  The command-line argument
+    # specifies what is needed.
+    if len(sys.argv) > 1:
+        prompt = sys.argv[1]
+        if not prompt.lower().endswith('password: '):
+            sys.stderr.write(prompt)
+            sys.stderr.write('\n')
+            sys.exit(1)
+
+    address = os.getenv('PSSH_ASKPASS_SOCKET')
+    if not address:
+        sys.stderr.write(textwrap.fill("pssh error: SSH requested a password."
+                " Please create SSH keys or use the -A option to provide a"
+                " password."))
+        sys.stderr.write('\n')
+        sys.exit(1)
+
+    sock = socket.socket(socket.AF_UNIX)
+    try:
+        sock.connect(address)
+    except socket.error:
+        _, e, _ = sys.exc_info()
+        message = e.args[1]
+        sys.stderr.write("Couldn't bind to %s: %s.\n" % (address, message))
+        sys.exit(2)
+
+    try:
+        password = sock.makefile().read()
+    except socket.error:
+        sys.stderr.write("Socket error.\n")
+        sys.exit(3)
+
+    print(password)
+
+
+if __name__ == '__main__':
+    askpass_main()