Hi Dave,
On Feb 11, 2013, at 9:22 AM, Dave Angel <[email protected]> wrote:
> Exactly how are you sending "hexadecimal" ? If that 0xad (which is only one
> byte, what about the other 3 ?) is intended to be a C description, then it's
> certainly not hex, it's binary. And probably little-endian, to boot. That's
> a mistake, as network protocols almost always use big-endian.
>
> So what is the range of values for the length, and how are they actually
> encoded? Are they uint32 in native binary format? And are you permitted to
> change the encoding, to fix it? (If it were my choice, I'd make it a
> printable decimal value, first choice, or printable hex, second choice.)
They are ASCII stream, actually JSON with the exception of the first 4 bytes. I
avoided using struct class for this as it's overkill for my application.
So the idea is that i code the length to a max of 0xff (max length of 256
bytes), I would only have to assign 4 bytes to it. If i need 1k length, i just
need to increase it to 6 bytes or 4 if i decide to strip the 0x.
the code for the function is as follows:
def request_get_session(sock, jmsg):
# append message length
plen = hex(len(jmsg))
msg = '{0}{1}'.format(plen, jmsg)
print 'sending data'
n = sock.send(msg)
str = '{0} bytes sent: {1}'.format(n, msg)
print str
# receive message length
print 'receiving data'
mlen = sock.recv(4)
try:
nbuf = int(mlen, 16)
except ValueError as e:
print 'invalid length type'
return -1
print 'message length is {0}'.format(nbuf)
while True:
buf = sock.recv(nbuf)
if not buf:
break
slen = len(buf)
str = "{0} bytes received: {1}".format(slen, buf)
print str
return 0
>
>>
>> I've managed to receive and translate the message length until I reach my
>> second recv which I readjusted the buffer size to include the new message
>> length.
>>
>> However that failed and recv received 0 bytes. I implemented the same
>> algorithm on the server side using C and it work so appreciate if you can
>> help me on this.
>>
>> # receive message length
>> print 'receiving data'
>> mlen = sock.recv(4)
>> try:
>> nbuf = int(mlen, 16)
>
> That supposes the count is being sent as a printable string of hex digits.
> That's not what I concluded above.
That is what I meant. it just an ascii string.
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