+class Buffer:
+ def __init__(self,s):
+ '''Buffer a pre-created socket.
+ '''
+ self.sock = s
+ self.buffer = b''
+
+ def get_bytes(self,n):
+ '''Read exactly n bytes from the buffered socket.
+ Return remaining buffer if <n bytes remain and socket closes.
+ '''
+ while len(self.buffer) < n:
+ data = self.sock.recv(1024)
+ if not data:
+ data = self.buffer
+ self.buffer = b''
+ return data
+ self.buffer += data
+ # split off the message bytes from the buffer.
+ data,self.buffer = self.buffer[:n],self.buffer[n:]
+ return data
+
+ def put_bytes(self,data):
+ self.sock.sendall(data)
+
+ def get_utf8(self):
+ '''Read a null-terminated UTF8 data string and decode it.
+ Return an empty string if the socket closes before receiving a null.
+ '''
+ while b'\x00' not in self.buffer:
+ data = self.sock.recv(1024)
+ if not data:
+ return ''
+ self.buffer += data
+ # split off the string from the buffer.
+ data,_,self.buffer = self.buffer.partition(b'\x00')
+ return data.decode()
+
+ def put_utf8(self,s):
+ if '\x00' in s:
+ raise ValueError('string contains delimiter(null)')
+ self.sock.sendall(s.encode() + b'\x00')
