[PATCH 0/3] Add support for XML-RPC over SSH

[PATCH 0/3] Add support for XML-RPC over SSH

[Anthony Liguori]

The following set of patches add support to Xend and xm for XML-RPC over 
SSH.  These patches are small and pretty self-contained so they 
shouldn't hinder the introduction of XML-RPC over HTTPS.  There are a 
number of good reasons to support XML-RPC over SSH.  It requires no 
additional open ports simplifying firewall configuration.  There's no 
additional server configuration (or certificate creation).  It also is 
rather easy to support from a client perspective.

I've tested this series with xm-test and there are no new unexpected 
failures[1].  The xm-test runs were done with both the httpu protocol 
and the ssh protocol.

This series assumes the application of the XML-RPC Keep-Alive patch I 
previously posted.

[1] One of the non-root tests unexpectedly passed since the user I was 
running authenticated over ssh as root.

Regards,

Anthony Liguori

[PATCH 1/3] Add an xm serve command

[Anthony Liguori]

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This is the server-side support required for XML-RPC over SSH.

Regards,

Anthony Liguori

[-- Attachment #2: xm-serve.diff --]
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# HG changeset patch
# User anthony@rhesis.austin.ibm.com
# Node ID cf8e253723daf8b95b54b24f6988a8e74c6cc0aa
# Parent  a0212dab2954807a979058d91b246564a7bf2cc2
Add an xm serve command.

This command proxies the Xend XML-RPC over stdio.  This is similiar to
mercurial's hg serve --stdio command.

The most obvious use of this command is remote XML-RPC invocation over SSH.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff -r a0212dab2954 -r cf8e253723da tools/python/xen/xm/main.py
--- a/tools/python/xen/xm/main.py	Sat Jun 10 19:07:26 2006
+++ b/tools/python/xen/xm/main.py	Sat Jun 10 19:11:55 2006
@@ -41,6 +41,7 @@
 import xen.xend.XendClient
 from xen.xend.XendClient import server
 from xen.util import security
+from select import select
 
 # getopt.gnu_getopt is better, but only exists in Python 2.3+.  Use
 # getopt.getopt if gnu_getopt is not available.  This will mean that options
@@ -124,6 +125,7 @@
 loadpolicy_help = "loadpolicy <policy>              Load binary policy into hypervisor"
 makepolicy_help = "makepolicy <policy>              Build policy and create .bin/.map files"
 labels_help     = "labels [policy] [type=DOM|..]    List <type> labels for (active) policy."
+serve_help      = "serve                            Proxy Xend XML-RPC over stdio"
 
 short_command_list = [
     "console",
@@ -171,7 +173,8 @@
 host_commands = [
     "dmesg",
     "info",
-    "log"
+    "log",
+    "serve",
     ]
 
 scheduler_commands = [
@@ -833,6 +836,32 @@
     arg_check(args, "log", 0)
     
     print server.xend.node.log()
+
+def xm_serve(args):
+    arg_check(args, "serve", 0)
+
+    from fcntl import fcntl, F_SETFL
+    
+    s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+    s.connect(xen.xend.XendClient.XML_RPC_SOCKET)
+    fcntl(sys.stdin, F_SETFL, os.O_NONBLOCK)
+
+    while True:
+        iwtd, owtd, ewtd = select([sys.stdin, s], [], [])
+        if s in iwtd:
+            data = s.recv(4096)
+            if len(data) > 0:
+                sys.stdout.write(data)
+                sys.stdout.flush()
+            else:
+                break
+        if sys.stdin in iwtd:
+            data = sys.stdin.read(4096)
+            if len(data) > 0:
+                s.sendall(data)
+            else:
+                break
+    s.close()
 
 def parse_dev_info(info):
     def get_info(n, t, d):
@@ -1072,6 +1101,7 @@
     "dmesg": xm_dmesg,
     "info": xm_info,
     "log": xm_log,
+    "serve": xm_serve,
     # scheduler
     "sched-bvt": xm_sched_bvt,
     "sched-bvt-ctxallow": xm_sched_bvt_ctxallow,

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[PATCH 2/3] Add SSH over XML-RPC support to xmlrpclib2.ServerProxy

[Anthony Liguori]

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This is the client-side support for SSH over XML-RPC.

Regards,

Anthony Liguori

[-- Attachment #2: sshtransport.diff --]
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# HG changeset patch
# User anthony@rhesis.austin.ibm.com
# Node ID 03bbc156d3e8fb01eee2af990176bb64e012c4e1
# Parent  cf8e253723daf8b95b54b24f6988a8e74c6cc0aa
Add support to our ServerProxy class for XML-RPC over SSH.

This adds a new XML-RPC transport (SSHTransport) and a new supported
protocol to the ServerProxy class.  This protocol is accessed with a URI of
the following form:

  ssh://[user@]hostname[/path]

While xm makes too many assumptions about being on a local system for all
commands to work when a remote URI is used, many of the commands do work.

This is mostly useful to people who are using xmlrpclib2 to write Xen
management tools.  It may prove more useful in the future to support
authenticated migration though.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff -r cf8e253723da -r 03bbc156d3e8 tools/python/xen/util/xmlrpclib2.py
--- a/tools/python/xen/util/xmlrpclib2.py	Sat Jun 10 19:11:55 2006
+++ b/tools/python/xen/util/xmlrpclib2.py	Sat Jun 10 19:16:33 2006
@@ -24,13 +24,51 @@
 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
 import SocketServer
 
-import xen.xend.XendClient
 from xen.xend.XendLogging import log
+
+class SSHTransport(object):
+    def __init__(self, host, user, askpass=None):
+        if askpass:
+            f = open('/dev/tty', 'w')
+            os.environ['SSH_ASKPASS'] = askpass
+            ioctl(f.fileno(), termios.TIOCNOTTY)
+            f.close()
+            
+        self.ssh = Popen(['ssh', '%s@%s' % (user, host), 'xm serve'],
+                         bufsize=0, stdin=PIPE, stdout=PIPE)
+
+    def request(self, host, handler, request_body, verbose=0):
+        p, u = getparser()
+        self.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))
+        self.ssh.stdin.flush()
+
+        content_length = 0
+        line = self.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 = self.ssh.stdout.readline()
+        content = self.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 +138,22 @@
             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
+                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 +201,7 @@
         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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[PATCH 3/3] Let xm user choose XML-RPC URI

[Anthony Liguori]

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This patch let's a user (via the XM_SERVER environment variable) choose 
which XML-RPC URI is used within xm.

Regards,

Anthony Liguori

[-- Attachment #2: xm_server.diff --]
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# HG changeset patch
# User anthony@rhesis.austin.ibm.com
# Node ID f8fcaee58fc1f7e13ae8443336a80de4c4e50538
# Parent  03bbc156d3e8fb01eee2af990176bb64e012c4e1
Use an environmental variable (XM_SERVER) to determine XML-RPC URI.

This allows users to invoke xm against a remote server.  This is much more
useful though for exercising XML-RPC transports with xm-test though since
xm-test will continue to (mostly) function if the URI is localhost.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff -r 03bbc156d3e8 -r f8fcaee58fc1 tools/python/xen/xend/XendClient.py
--- a/tools/python/xen/xend/XendClient.py	Sat Jun 10 19:16:33 2006
+++ b/tools/python/xen/xend/XendClient.py	Sat Jun 10 19:19:02 2006
@@ -18,6 +18,7 @@
 #============================================================================
 
 from xen.util.xmlrpclib2 import ServerProxy
+import os
 
 XML_RPC_SOCKET = "/var/run/xend/xmlrpc.sock"
 
@@ -25,4 +26,8 @@
 ERROR_GENERIC = 2
 ERROR_INVALID_DOMAIN = 3
 
-server = ServerProxy('httpu:///var/run/xend/xmlrpc.sock')
+uri = 'httpu:///var/run/xend/xmlrpc.sock'
+if os.environ.has_key('XM_SERVER'):
+    uri = os.environ['XM_SERVER']
+
+server = ServerProxy(uri)

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