我有一个应用程序,软件定义无线电,在一个端口上广播UDP数据包,告诉听众已经设置了什么频率和解调模式(等等).

我编写了一个演示python客户端(下面的代码)来监听端口,并将相应数据包中的信息转储到控制台.

这些都在OSX 10.6,Snow Leopard下运行.他们在那里工作.

我的问题是：Python应用程序必须在无线电应用程序之前启动,或者在绑定期间声称端口已在使用(ERRNO 47),我不明白为什么.无线电应用正在广播UDP;当然我想容纳多个听众 – 这就是广播的想法,或者至少,所以我想.

所以这里是Python代码(由于堆栈溢出真的很愚蠢“make-it-code”缩进,缩进有点混乱,但我保证你没关系)：

#!/usr/bin/python

import select, socket

# AA7AS - for SdrDx UDP broadcast

# this is a sample python script that captures the UDP messages

# that are coming from SdrDx. SdrDx tells you what frequency and

# mode it has been set to. This, in turn, would be used to tell

# another radio to tune to that frequency and mode.

# UDP packet from SdrDx is zero terminated, but receiving the

# packet makes it seem like the string contains zeros all the

# way out to the 1024th character. This function extracts a

# python string up to the point where it hits the first zero,

# then returns that string.

# -----------------------------------------------------------

def zeroterm(msg):

counter = 0;

for c in msg:

if ord(c) != 0:

counter += 1

strn = msg[:counter]

return strn

port = 58083 # port where we expect to get a msg

bufferSize = 1024 # room for message

# Create port to listen upon

# --------------------------

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

try:

s.bind(('', port))

except:

print 'failure to bind'

s.close()

raise

s.setblocking(0)

# Listen for messages

# -------------------

looping = True

while looping:

try:

result = select.select([s],[],[])

except: # you can kill the client here with control-c in its shell

s.close() # must close socket

print 'Closing, exception encountered during select' # warn

raise SystemExit # and quit

msg = result[0][0].recv(bufferSize) # actually fetch the UDP data

msg = zeroterm(msg) # convert content into python string

# in next line, [] contain optional repeats

# message format is keyword:data[|keyword:data]

# where from 1...n keyword:data pairs may appear, up to 1024 bytes

# ----------------------------------------------------------------

try:

msgs = msg.split('|') # can be more than one message in packet

except: # failed to split

msgs = [] # on the other hand, can just be one. :)

msgs.append(msg) # so build array with that one.

for m in msgs: # now, for every message we have

keyw,data = m.split(':') # break into keyword and data

print keyw + "-->" + data # you'd do something with this

if keyw == "closing": # Our client terminates when SdrDx does

looping = False # loop stops

s.close() # must close socket

print 'Normal termination'

作为参考,这是发送UDP消息的Qt代码：

建立：

bcast = new QHostAddress("192.168.1.255");

if (bcast)

{

udpSocketSend = new QUdpSocket(0);

if (udpSocketSend)

{

udpSocketSend->bind(*bcast, txudp);

}

}

广播：

if (udpSocketSend)

{

QByteArray *datagram = new QByteArray(1024,0); // datagram is full of zeroes

strcpy(datagram->data(),msg); // except where text message is in it at beginning

udpSocketSend->writeDatagram(*datagram, QHostAddress::Broadcast,txudp); // send

}