diff --git a/src/server.py b/src/server.py
--- a/src/server.py
+++ b/src/server.py
@@ -32,6 +32,7 @@ class Server:
 	def __init__(self,filename,treeFile=""):
 		self._filename=filename
 		self._treeFile=treeFile
+		self._locked=False
 
 		if treeFile:
 			self._tree=HashTree.load(treeFile)
@@ -56,8 +57,8 @@ class Server:
 		while True:
 			with Connection(self._ss,self._ssl) as (incoming, outcoming):
 				try:
-					while True:
-						if not self._serveOne(incoming,outcoming): return
+					while self._serveOne(incoming,outcoming):
+						pass
 				except AssertionError:
 					continue
 
@@ -67,6 +68,7 @@ class Server:
 		if jsonData["command"]=="init":
 			assert jsonData["blockSize"]==self.BLOCK_SIZE
 			assert jsonData["blockCount"]==self._tree.leafCount
+			self._locked=True
 			outcoming.writeMsg({"command": "ack"})
 
 		elif jsonData["command"]=="req":
@@ -80,6 +82,7 @@ class Server:
 
 		elif jsonData["command"]=="end":
 			self._finalize()
+			self._locked=False
 			return False
 
 		else: