[PATCH 2/4] Client support for XML-RPC over SSH

[Anthony Liguori <aliguori@us.ibm.com>]

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This incorporates Ewan's error reporting suggestion and uses lazy 
evaluation to initialize the ssh connection.

Regards,

Anthony Liguori

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# HG changeset patch
# User root@rhesis.austin.ibm.com
# Node ID ee7eb0713498591c50f43cabfcf48608b0b7aa32
# Parent  84596b81600e09c83e85eb8c7517747d57d1da98
This patch adds client side support for XML-RPC over ssh.  It differs from 
the previous submission in that it now uses lazy evaluation to connect
to the remote server and provides more user friendly error messages if ssh
is not available.

Signed-off-by: Anthony Liguori

diff -r 84596b81600e -r ee7eb0713498 tools/python/xen/util/xmlrpclib2.py
--- a/tools/python/xen/util/xmlrpclib2.py	Wed Jun 14 17:09:48 2006
+++ b/tools/python/xen/util/xmlrpclib2.py	Wed Jun 14 19:14:27 2006
@@ -24,13 +24,67 @@
 import types
 
 from httplib import HTTPConnection, HTTP
-from xmlrpclib import Transport
+from xmlrpclib import Transport, getparser, Fault
 from SimpleXMLRPCServer import SimpleXMLRPCServer, SimpleXMLRPCRequestHandler
-import xmlrpclib, socket, os, stat
+from subprocess import Popen, PIPE
+from getpass import getuser
+from fcntl import ioctl
+import xmlrpclib, socket, os, stat, termios, errno
 import SocketServer
 
-import xen.xend.XendClient
 from xen.xend.XendLogging import log
+
+class SSHTransport(object):
+    def __init__(self, host, user, askpass=None):
+        self.host = host
+        self.user = user
+        self.askpass = askpass
+        self.ssh = None
+
+    def getssh(self):
+        if self.ssh == None:
+            if self.askpass:
+                f = open('/dev/tty', 'w')
+                try:
+                    os.environ['SSH_ASKPASS'] = self.askpass
+                    ioctl(f.fileno(), termios.TIOCNOTTY)
+                finally:
+                    f.close()
+
+            cmd = ['ssh', '%s@%s' % (self.user, self.host), 'xm serve']
+            try:
+                self.ssh = Popen(cmd, bufsize=0, stdin=PIPE, stdout=PIPE)
+            except OSError, (err, msg):
+                if err == errno.ENOENT:
+                    raise Fault(0, "ssh executable not found!")
+                raise
+        return self.ssh
+
+    def request(self, host, handler, request_body, verbose=0):
+        p, u = getparser()
+        ssh = self.getssh()
+        ssh.stdin.write("""POST /%s HTTP/1.1
+User-Agent: Xen
+Host: %s
+Content-Type: text/xml
+Content-Length: %d
+
+%s""" % (handler, host, len(request_body), request_body))
+        ssh.stdin.flush()
+
+        content_length = 0
+        line = ssh.stdout.readline()
+        if line.split()[1] != '200':
+            raise Fault(0, 'Server returned %s' % (' '.join(line[1:])))
+        
+        while line not in ['', '\r\n', '\n']:
+            if line.lower().startswith('content-length:'):
+                content_length = int(line[15:].strip())
+            line = ssh.stdout.readline()
+        content = ssh.stdout.read(content_length)
+        p.feed(content)
+        p.close()
+        return u.close()
 
 
 # A new ServerProxy that also supports httpu urls.  An http URL comes in the
@@ -100,9 +154,24 @@
             if protocol == 'httpu':
                 uri = 'http:' + rest
                 transport = UnixTransport()
+            elif protocol == 'ssh':
+                if not rest.startswith('//'):
+                    raise ValueError("Invalid ssh URL '%s'" % uri)
+                rest = rest[2:]
+                user = getuser()
+                path = 'RPC2'
+                if rest.find('@') != -1:
+                    (user, rest) = rest.split('@', 1)
+                if rest.find('/') != -1:
+                    (host, rest) = rest.split('/', 1)
+                    if len(rest) > 0:
+                        path = rest
+                else:
+                    host = rest
+                transport = SSHTransport(host, user)
+                uri = 'http://%s/%s' % (host, path)
         xmlrpclib.ServerProxy.__init__(self, uri, transport, encoding,
                                        verbose, allow_none)
-
 
     def __request(self, methodname, params):
         response = xmlrpclib.ServerProxy.__request(self, methodname, params)
@@ -150,6 +219,7 @@
         except xmlrpclib.Fault, fault:
             response = xmlrpclib.dumps(fault)
         except Exception, exn:
+            import xen.xend.XendClient
             log.exception(exn)
             response = xmlrpclib.dumps(
                 xmlrpclib.Fault(xen.xend.XendClient.ERROR_INTERNAL, str(exn)))

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