Store the host config in a per-host config file.

remoting/tools/me2me_virtual_host.py

Index: remoting/tools/me2me_virtual_host.py
diff --git a/remoting/tools/me2me_virtual_host.py b/remoting/tools/me2me_virtual_host.py
index f8a8baaa3566e7e22119527f71aa5f5a4bc090ca..23ca7b650edd7b7226693763fe27f7d0ca4f66f1 100755
--- a/remoting/tools/me2me_virtual_host.py
+++ b/remoting/tools/me2me_virtual_host.py
@@ -29,6 +29,9 @@ import keygen
 
 REMOTING_COMMAND = "remoting_me2me_host"
 
+# Command-line switch for passing the config path to remoting_me2me_host.
+HOST_CONFIG_SWITCH_NAME = "host-config"
+
 SCRIPT_PATH = os.path.dirname(sys.argv[0])
 if not SCRIPT_PATH:
   SCRIPT_PATH = os.getcwd()
@@ -260,10 +263,11 @@ class Desktop:
     if not session_proc.pid:
       raise Exception("Could not start X session")
 
-  def launch_host(self):
+  def launch_host(self, host):
     # Start remoting host
-    command = locate_executable(REMOTING_COMMAND)
-    self.host_proc = subprocess.Popen(command, env=self.child_env)
+    args = [locate_executable(REMOTING_COMMAND),
+            "--%s=%s" % (HOST_CONFIG_SWITCH_NAME, host.config_file)]

[Wez, 2011/12/10 00:00:09]

Is it possible for |config_file| to contain anything that might confuse popen()?
 (see below)

[Lambros, 2011/12/10 02:00:31]

This shouldn't confuse popen(), because the whole --%s=%s constitutes a single
item of the args[] list, with no shell parsing involved.  And
remoting_me2me_host ought to parse everything from the first '=' to the end of
that args[] item as the filename.

+    self.host_proc = subprocess.Popen(args, env=self.child_env)
     if not self.host_proc.pid:
       raise Exception("Could not start remoting host")
 
@@ -287,7 +291,7 @@ def main():
       return 1
     auth.save_config()
 
-  host = Host(os.path.join(CONFIG_DIR, "host.json"))
+  host = Host(os.path.join(CONFIG_DIR, "host#%s.json" % socket.gethostname()))

[Wez, 2011/12/10 00:00:09]

Is socket.gethostname() reliable, e.g. if the host has multiple names do we
always get the first?  (I think so, but I'm not sure...)

Can host names contain anything we'd be scared to have routed into a file path? 
Perhaps we should use a hash of the name, rather than the name itself?

[Lambros, 2011/12/10 02:00:31]

Python doc isn't helpful here, it says only that it returns the machine's
hostname.  socket.getfqdn() may be better, I'm not sure.
Yeah.  The gotcha is that hostnames can be 255 chars long, which is also the
limit for UNIX filenames.  The allowed characters for hostnames (alphanum, dash,
dot) are OK here.  The problem is just the maximum length :)

Done.

 
   if not host.load_config():
     host.create_config(auth)
@@ -298,7 +302,7 @@ def main():
   desktop = Desktop()
   desktop.launch_x_server()
   desktop.launch_x_session()
-  desktop.launch_host()
+  desktop.launch_host(host)
 
   while True:
     pid, status = os.wait()
@@ -310,7 +314,7 @@ def main():
 
     if pid == desktop.host_proc.pid:
       logging.info("Host process terminated, relaunching")
-      desktop.launch_host()
+      desktop.launch_host(host)
 
 if __name__ == "__main__":
   logging.basicConfig(level=logging.DEBUG)