Well the thing is just because you sniffed the packet off the wire
doesn't in any way mean the "client" (i.e. the SIP software) has
actually received it. In fact, a pretty reasonable piece of SIP code
(I'll just write Python pseudo-code for brevity) might look something like:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect( (server, port) )
s.send('REGISTER ....')
while True :
bytes = s.recv(256)
if len(bytes) == 0 :
# uh-oh, the remote end closed the socket
And in fact even if the OS has received the [FIN,ACK] already when
s.send() is called, this will *not* cause an error. The send() will
complete successfully. Try it!
On 5/7/13 2:58 PM, Khoa Pham wrote:
> @Jens, thanks for reply
>
> But client already received the [FIN,ACK] from server, it should know
> that sending REGISTER does not make sense anymore
>
>
> On Tue, May 7, 2013 at 12:13 PM, Jens Jorgensen <jbj1 at ultraemail.net
> <mailto:jbj1 at ultraemail.net>> wrote:
>
> You make it sound like you want the client to hang up?! As you
> know, the primary way a program finds out if a socket is closed is
> to try reading or writing on it. In this case the server has
> closed its end of the socket but the client probably doesn't know
> that (yet)--evidently because it thought it would get the chance
> to REGISTER
>
> On 5/6/13 5:15 PM, Khoa Pham wrote:
>> Hi pjsip team,
>>
>> When I make REGISTER request to server, I often receive this
>>
>> 1. client: SYN
>> 2. server: SYN, ACK
>> 3. client: ACK
>> 4. server: FIN, ACK
>> 5. client: REGISTER
>> 6. server: RST
>>
>> Why in step 5 does client not send FIN, ACK ??
>>
>> --
>> Khoa Pham
>> HCMC University of Science
>> Faculty of Information Technology
>>
>>
>> _______________________________________________
>> Visit our blog: http://blog.pjsip.org
>>
>> pjsip mailing list
>> pjsip at lists.pjsip.org <mailto:pjsip at lists.pjsip.org>
>> http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org
>
> --
> Jens B. Jorgensen
> jbj1 at ultraemail.net <mailto:jbj1 at ultraemail.net>
>
>
> _______________________________________________
> Visit our blog: http://blog.pjsip.org
>
> pjsip mailing list
> pjsip at lists.pjsip.org <mailto:pjsip at lists.pjsip.org>
> http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org
>
>
>
>
> --
> Khoa Pham
> HCMC University of Science
> Faculty of Information Technology
>
>
> _______________________________________________
> Visit our blog: http://blog.pjsip.org
>
> pjsip mailing list
> pjsip at lists.pjsip.org
> http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org
--
Jens B. Jorgensen
jbj1 at ultraemail.net
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