X11 forwarding support

protocol.txt

@@ -32,6 +32,7 @@ PROC	ABRT			200			(5)
 PROC	POLL	<pid>		200 <code>/450/500	check if process alive
 PROC	WAIT	<pid>		200 <code>/500		waitpid(pid)
 PROC	KILL	<pid> <signal>	200/500			kill(pid, signal)
+X11		<prot> <data>	354+200/500		(6)
 
 (1) valid arguments: mtu <n>, up <0|1>, name <name>, lladdr <addr>,
 broadcast <addr>, multicast <0|1>, arp <0|1>.
@@ -52,6 +53,10 @@ command. Answers 200/500 after processing the file descriptor.
 was successful, the process is started and the process ID is returned as the
 first token of the reply.
 
+(6) Enable X11 forwarding, using the specified protocol and data for
+authentication. A opened socket ready to receive X connections is passed over
+the channel. Answers 200/500 after transmitting the file descriptor.
+
 Sample session
 --------------
 

src/netns/environ.py

 # vim:ts=4:sw=4:et:ai:sts=4
 
-import os, os.path, subprocess, sys, syslog
+import os, os.path, socket, subprocess, sys, syslog
 from syslog import LOG_ERR, LOG_WARNING, LOG_NOTICE, LOG_INFO, LOG_DEBUG
 
 __all__ = ["ip_path", "tc_path", "brctl_path", "sysctl_path", "hz"]
-__all__ += ["tcpdump_path", "netperf_path"]
+__all__ += ["tcpdump_path", "netperf_path", "xauth_path", "xdpyinfo_path"]
 __all__ += ["execute", "backticks"]
+__all__ += ["find_listen_port"]
 __all__ += ["LOG_ERR", "LOG_WARNING", "LOG_NOTICE", "LOG_INFO", "LOG_DEBUG"]
 __all__ += ["set_log_level", "logger"]
 __all__ += ["error", "warning", "notice", "info", "debug"]
@@ -44,6 +45,8 @@ sysctl_path = find_bin_or_die("sysctl")
 # Optional tools
 tcpdump_path = find_bin("tcpdump")
 netperf_path = find_bin("netperf")
+xauth_path = find_bin("xauth")
+xdpyinfo_path = find_bin("xdpyinfo")
 
 # Seems this is completely bogus. At least, we can assume that the internal HZ
 # is bigger than this.
@@ -72,6 +75,17 @@ def backticks(cmd):
         raise RuntimeError("Error executing `%s': %s" % (" ".join(cmd), err))
     return out
 
+def find_listen_port(family = socket.AF_INET, type = socket.SOCK_STREAM,
+        proto = 0, addr = "127.0.0.1", min_port = 1, max_port = 65535):
+    s = socket.socket(family, type, proto)
+    for p in range(min_port, max_port + 1):
+        try:
+            s.bind((addr, p))
+            return s, p
+        except socket.error:
+            pass
+    raise RuntimeError("Cannot find an usable port in the range specified")
+
 # Logging
 _log_level = LOG_WARNING
 _log_use_syslog = False

src/netns/node.py

@@ -15,7 +15,7 @@ class Node(object):
         s = sorted(Node._nodes.items(), key = lambda x: x[0])
         return [x[1] for x in s]
 
-    def __init__(self, nonetns = False):
+    def __init__(self, nonetns = False, forward_X11 = False):
         """Create a new node in the emulation. Implemented as a separate
         process in a new network name space. Requires root privileges to run.
 
@@ -32,6 +32,8 @@ class Node(object):
         self._pid = pid
         debug("Node(0x%x).__init__(), pid = %s" % (id(self), pid))
         self._slave = netns.protocol.Client(fd, fd)
+        if forward_X11:
+            self._slave.enable_x11_forwarding()
 
         Node._nodes[Node._nextnode] = self
         Node._nextnode += 1

src/netns/subprocess_.py

@@ -4,7 +4,7 @@
 import fcntl, grp, os, pickle, pwd, signal, select, sys, time, traceback
 
 __all__ = [ 'PIPE', 'STDOUT', 'Popen', 'Subprocess', 'spawn', 'wait', 'poll',
-        'system', 'backticks', 'backticks_raise' ]
+        'get_user', 'system', 'backticks', 'backticks_raise' ]
 
 # User-facing interfaces
 
@@ -280,19 +280,7 @@ def spawn(executable, argv = None, cwd = None, env = None, close_fds = False,
     assert not (set([0, 1, 2]) & set(filtered_userfd))
 
     if user != None:
-        if str(user).isdigit():
-            uid = int(user)
-            try:
-                user = pwd.getpwuid(uid)[0]
-            except:
-                raise ValueError("UID %d does not exist" % int(user))
-        else:
-            try:
-                uid = pwd.getpwnam(str(user))[2]
-            except:
-                raise ValueError("User %s does not exist" % str(user))
-
-        gid = pwd.getpwuid(uid)[3]
+        user, uid, gid = get_user(user)
         groups = [x[2] for x in grp.getgrall() if user in x[3]]
 
     (r, w) = os.pipe()
@@ -390,6 +378,21 @@ def wait(pid):
     """Wait for process to die and return the exit code."""
     return _eintr_wrapper(os.waitpid, pid, 0)[1]
 
+def get_user(user):
+    "Take either an username or an uid, and return a tuple (user, uid, gid)."
+    if str(user).isdigit():
+        uid = int(user)
+        try:
+            user = pwd.getpwuid(uid)[0]
+        except KeyError:
+            raise ValueError("UID %d does not exist" % int(user))
+    else:
+        try:
+            uid = pwd.getpwnam(str(user))[2]
+        except KeyError:
+            raise ValueError("User %s does not exist" % str(user))
+    gid = pwd.getpwuid(uid)[3]
+    return user, uid, gid
 
 # internal stuff, do not look!
 

test/test_core.py

@@ -189,5 +189,31 @@ class TestGlobal(unittest.TestCase):
 
         self.assertEquals(a.wait(), 0)
 
+class TestX11(unittest.TestCase):
+    @test_util.skipUnless("DISPLAY" in os.environ, "Test requires working X11")
+    @test_util.skipUnless(netns.environ.xdpyinfo_path, "Test requires xdpyinfo")
+    def test_run_xdpyinfo(self):
+        xdpy = netns.environ.xdpyinfo_path
+        info = netns.environ.backticks([xdpy])
+        # remove first line, contains the display name
+        info = info.partition("\n")[2]
+        n = netns.Node(nonetns = True, forward_X11 = True)
+        info2 = n.backticks([xdpy])
+        info2 = info2.partition("\n")[2]
+        self.assertEquals(info, info2)
+
+    @test_util.skipUnless(os.getuid() == 0, "Test requires root privileges")
+    @test_util.skipUnless("DISPLAY" in os.environ, "Test requires working X11")
+    @test_util.skipUnless(netns.environ.xdpyinfo_path, "Test requires xdpyinfo")
+    def test_run_xdpyinfo_netns(self):
+        xdpy = netns.environ.xdpyinfo_path
+        info = netns.environ.backticks([xdpy])
+        # remove first line, contains the display name
+        info = info.partition("\n")[2]
+        n = netns.Node(forward_X11 = True)
+        info2 = n.backticks([xdpy])
+        info2 = info2.partition("\n")[2]
+        self.assertEquals(info, info2)
+
 if __name__ == '__main__':
     unittest.main()