def server(reqcode):
#retrieve the IP address of server's machine
hostname = socket.gethostbyname(socket.gethostname())
serverSocket = getsocket(socket.SOCK_STREAM)
print 'SERVER_PORT=' + str(serverSocket.getsockname()[1])
#start listening, queue 0 connections because we only have one client at a time
serverSocket.listen(0)
while True:
sys.stderr.write('Accepting Connection...\n')
conn, addr = serverSocket.accept()
# accept a TCP connection from the client
# conn is the socket endpoint of the client and addr is the address bound to conn
# receive 32 bytes, enough size for an integer
data = conn.recv(32)
if reqcode != data:
# received incorrect req_code from client, close TCP connection with client
conn.shutdown(1)
continue
# create a UDP socket
serverUDP = getsocket(socket.SOCK_DGRAM)
# send the port number bound to the UDP socket over to the client
conn.sendall(str(serverUDP.getsockname()[1]))
# receive the message from client
sys.stderr.write('Waiting to receive message...\n')
message, clientaddr = udpreceiver(serverUDP, BUFSIZE)
#reverse message
message = message[::-1]
sys.stderr.write('Sending reversed message to client...\n')
udpsender(serverUDP, message, clientaddr)
# close UDP socket
serverUDP.close()
# close TCP connection
serverSocket.close()
def client(saddr, nport, reqcode, message):
#retrieve the IP address of server's machine
hostname = socket.gethostbyname(socket.gethostname())
clientSocket = getsocket(socket.SOCK_STREAM)
# connect to server's socket
try:
clientSocket.connect((saddr, int(nport)))
except socket.error:
sys.stderr.write('Connection to server failed\n')
exit(-1)
# send reqcode to server
clientSocket.sendall(reqcode)
# receive the UDP port used by the server
# enough size for a port number
udpport = clientSocket.recv(16)
# check if the server gives us the okay sign
if udpport == '':
sys.stderr.write('Given request code is incorrect\n')
clientSocket.close()
exit(-1)
# close TCP connection
clientSocket.close()
# create a UDP socket and send message, make sure the data is all sent
clientSocket = getsocket(socket.SOCK_DGRAM)
bytesSent = 0
sendaddr = (saddr, int(udpport))
# send the message through udp socket to server
udpsender(clientSocket, message, sendaddr)
# receive the reversed message through udp socket from server
reversedMsg = udpreceiver(clientSocket, BUFSIZE)[0]
print reversedMsg
# close socket
clientSocket.close()
