Don't pipe ncat communication - use stdin instead

Signed-off-by: Robert Breker <[email protected]>

Author: Robert Breker

src/xscontainer/docker.py

@@ -14,17 +14,19 @@
     "the VM that is reachable from Dom0.")
 
 
-def prepare_request_cmds(request_type, request):
-    # @todo: can we do something smarter then piping?
-    request_cmds = ['echo -e "%s %s HTTP/1.0\r\n"' % (request_type, request) +
-                    '| ncat -U %s' % (DOCKER_SOCKET_PATH)]
-    return request_cmds
+def prepare_request_cmd():
+    return ("ncat -U %s" % (DOCKER_SOCKET_PATH))
+
+
+def prepare_request_stdin(request_type, request):
+    return ("%s %s HTTP/1.0\r\n\r\n" % (request_type, request))
 
 
 def _interact_with_api(session, vmuuid, request_type, request,
                        message_error=False):
-    request_cmds = prepare_request_cmds(request_type, request)
-    stdout = ssh_helper.execute_ssh(session, vmuuid, request_cmds)
+    provided_stdin = prepare_request_stdin(request_type, request)
+    stdout = ssh_helper.execute_ssh(session, vmuuid, prepare_request_cmd(),
+                                    stdin_input=provided_stdin)
     headerend = stdout.index('\r\n\r\n')
     header = stdout[:headerend]
     body = stdout[headerend + 4:]

src/xscontainer/docker_monitor/__init__.py

@@ -118,11 +118,12 @@ def __monitor_vm_events(self):
         vmuuid = self.get_uuid()
         ssh_client = ssh_helper.prepare_ssh_client(session, vmuuid)
         try:
-            cmd = "ncat -U %s" % (docker.DOCKER_SOCKET_PATH)
+            cmd = docker.prepare_request_cmd()
             log.info("__monitor_vm_events is running '%s' on VM '%s'"
                      % (cmd, vmuuid ))
             stdin, stdout, _ = ssh_client.exec_command(cmd)
-            stdin.write("GET /events HTTP/1.0\r\n\r\n")
+            stdin.write(docker.prepare_request_stdin('GET', '/events'))
+            stdin.channel.shutdown_write()
             self._ssh_client = ssh_client
             data = ""
             # set unblocking io for select.select

src/xscontainer/ssh_helper.py

@@ -100,7 +100,7 @@ def prepare_ssh_client(session, vmuuid):
     return client
 
 
-def execute_ssh(session, vmuuid, cmd):
+def execute_ssh(session, vmuuid, cmd, stdin_input=None):
     # The heavy weight is docker ps with plenty of containers.
     # Assume 283 bytes per container.
     # 300KB should be enough for 1085 containers.
@@ -111,9 +111,15 @@ def execute_ssh(session, vmuuid, cmd):
             client = prepare_ssh_client(session, vmuuid)
             if isinstance(cmd, list):
                 cmd = ' '.join(cmd)
-            log.info("execute_ssh will run '%s' on vm %s"
-                     % (cmd, vmuuid))
-            _, stdout, _ = client.exec_command(cmd)
+            stripped_stdin_input = stdin_input
+            if stripped_stdin_input:
+                stripped_stdin_input = stripped_stdin_input.strip()
+            log.info("execute_ssh will run '%s' with stdin '%s' on vm %s"
+                     % (cmd, stripped_stdin_input, vmuuid))
+            stdin, stdout, _ = client.exec_command(cmd)
+            if stdin_input:
+                stdin.write(stdin_input)
+                stdin.channel.shutdown_write()
             output = stdout.read(max_read_size)
             if stdout.read(1) != "":
                 raise SshException("too much data was returned when executing"