From 990e977d86a1fa58f86f381eba7430957ddbc477 Mon Sep 17 00:00:00 2001
From: Likun Zhang <zlkzhy@gmail.com>
Date: Tue, 8 Jun 2010 11:41:54 +0000
Subject: When xfrout is launched, check whether the socket file is being used
 by one running xfrout process, if it is, exit from python. If the file isn't
 a socket file or nobody is listening, it will be removed. If it can't be
 removed, exit from python.

git-svn-id: svn://bind10.isc.org/svn/bind10/trunk@2091 e5f2f494-b856-4b98-b285-d166d9295462
---
 src/bin/xfrout/xfrout.py.in | 47 ++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 40 insertions(+), 7 deletions(-)

(limited to 'src/bin/xfrout/xfrout.py.in')

diff --git a/src/bin/xfrout/xfrout.py.in b/src/bin/xfrout/xfrout.py.in
index af1506ec69..d0580553ab 100644
--- a/src/bin/xfrout/xfrout.py.in
+++ b/src/bin/xfrout/xfrout.py.in
@@ -28,6 +28,7 @@ import os
 from isc.config.ccsession import *
 from isc.cc import SessionError
 import socket
+import errno
 from optparse import OptionParser, OptionValueError
 try:
     from bind10_xfr import *
@@ -57,7 +58,13 @@ class XfroutSession(BaseRequestHandler):
     def handle(self):
         fd = recv_fd(self.request.fileno())
         if fd < 0:
-            raise XfroutException("failed to receive the FD for XFR connection")
+            # This may happen when one xfrout process try to connect to
+            # xfrout unix socket server, to check whether there is another
+            # xfrout running. 
+            print("[b10-xfrout] Failed to receive the FD for XFR connection, "
+                  "maybe because another xfrout process was started.")
+            return
+
         data_len = self.request.recv(2)
         msg_len = struct.unpack('!H', data_len)[0]
         msgdata = self.request.recv(msg_len)
@@ -277,18 +284,44 @@ class UnixSockServer(ThreadingUnixStreamServer):
     '''The unix domain socket server which accept xfr query sent from auth server.'''
 
     def __init__(self, sock_file, handle_class, shutdown_event, config_data):
-        try:
-            os.unlink(sock_file)
-        except:
-            pass
- 
+        self._remove_unused_sock_file(sock_file)
         self._sock_file = sock_file
         ThreadingUnixStreamServer.__init__(self, sock_file, handle_class)
         self._lock = threading.Lock()
         self._transfers_counter = 0
         self._shutdown_event = shutdown_event
         self.update_config_data(config_data)
-    
+
+    def _remove_unused_sock_file(self, sock_file):
+        '''Try to remove the socket file. If the file is being used 
+        by one running xfrout process, exit from python. 
+        If it's not a socket file or nobody is listening
+        , it will be removed. If it can't be removed, exit from python. '''
+        if self._sock_file_in_use(sock_file):
+            print("[b10-xfrout] Fail to start xfrout process, unix socket" 
+                  " file '%s' is being used by another xfrout process" % sock_file)
+            sys.exit(0)
+        else:
+            if not os.path.exists(sock_file):
+                return
+
+            try:
+                os.unlink(sock_file)
+            except OSError as err:
+                print('[b10-xfrout] Fail to remove file ' + sock_file, err)
+                sys.exit(0)
+   
+    def _sock_file_in_use(self, sock_file):
+        '''Check whether the socket file 'sock_file' exists and 
+        is being used by one running xfrout process. If it is, 
+        return True, or else return False. '''
+        try:
+            sock = socket.socket(socket.AF_UNIX)
+            sock.connect(sock_file)
+        except socket.error as err:
+            return False
+        else:
+            return True 
 
     def shutdown(self):
         ThreadingUnixStreamServer.shutdown(self)
-- 
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