Check if port is already used

daemon.py

@@ -147,6 +147,7 @@ from shares import outboxUndoShareUpload
 from shares import addShare
 from shares import removeShare
 from shares import expireShares
+from utils import isPortInUse
 from utils import removeAvatarFromCache
 from utils import locatePost
 from utils import getCachedPostFilename
@@ -5481,6 +5482,11 @@ def runDaemon(mediaInstance: bool,maxRecentPosts: int, \
         pubHandler = partial(PubServerUnitTest)
     else:
         pubHandler = partial(PubServer)
+
+    if isPortInUse(proxyPort):
+        print('Process is already running on port '+str(proxyPort))
+        return False
+
     try:
         httpd = ThreadingHTTPServer(serverAddress, pubHandler)
     except Exception as e:

utils.py

@@ -11,6 +11,13 @@ import time
 import shutil
 import datetime
 import json
+import socket
+
+def isPortInUse(portNumber: int) -> bool:
+    """Returns true if the port is in use
+    """
+    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
+        return s.connect_ex(('localhost', portNumber)) == 0
 
 def removeAvatarFromCache(baseDir: str,actorStr: str) -> None:
     """Removes any existing avatar entries from the cache