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Dear Michael,

I found the problem. I made a mistake not to initialize the argument of flags
of sctp_recvmsg(). I thought it's an 'out' argument. After I assigned the
flags to 0 and then call sctp_recvmsg, everything runs perfect. Thank you
very much for your help!

Best Regards,
Xu Yun

-----Original Message-----
From: Michael Tuexen
[mailto:Michael.Tuexen AT micmac.franken.de]

Sent: Tuesday, August 09, 2005 9:21 PM
To: Thomas Dreibholz
Cc: discussion; Xu Yun,SCNB R&D NNC(BJ)
Subject: Re: [SCTP-Discussion] The difference between ext_sendto() and sct
p_sendx()

Hi Thomas,

could you check if there is a problem with sctp_recvmsg in the
socketapilib? Could it be that
it always peeks?

Thank you very much.

Best regards
Michael

On Aug 9, 2005, at 13:40 Uhr, Xu Yun,SCNB R&D NNC(BJ) wrote:

> Hello Michael,
>
> Thanks for your hints. I've tried sctp_sendmsg and it runs as we
> expected. But the receiving problem is still there: if I calls
> ext_recvfrom to receive message everything runs well, but when I turns
> to call sctp_recvmsg I got endless received messages.
> After checking the source code of ext_recvfrom and sctp_recvmsg, the
> only major difference between the two function is the argument
> 'receiveNotifications' of ext_recvmsg2() function. What's the
> difference behind this argument?
>
> BTW: In my last mail, I cut some unrelated code (including some lines
> about timeout operation) when I pasted it, and it may make you
> confused :) So the timeout should be the problem. I paste the
> waitfor_message() again:
>
> void* waitfor_message(void *not_used)
> {
> int ret;
> struct timeval timeout;
> int idx;
> fd_set rfds;
> m3ua_mgmt_ntfy_t ntfy;
> m3ua_user_ntfy_t u_ntfy;
> unsigned char msg[1024];
> unsigned int msglen = 0;
>
> timeout.tv_sec = 0;
> timeout.tv_usec = 0;
> while(1) {
> if (0 == timeout.tv_sec && 0 == timeout.tv_usec) {
> timeout.tv_sec = 1;
> timeout.tv_usec = 0;
> }
> rfds = readfds;
> ret = ext_select(FD_SETSIZE, &rfds, NULL, NULL, &timeout);
> if (0 == ret) {
> timeout.tv_sec = 0;
> timeout.tv_usec = 0;
> m3timer_ckexpiry(NULL);
> um3_timer_ckexpiry(NULL);
> }
> else if (0 < ret) {
> for (idx = 0; idx < MAX_LOCAL_EP; idx++)
> if (1 == from[idx].e_state &&
> FD_ISSET(from[idx].sockid,&rfds))
> get_message(idx, from[idx].sockid, msg, &msglen);
> }
> else {
> printf("ERRNO:%d\n", errno);
> perror("E_select_Fail");
> }
> while (-1 != m3ua_mgmt_ntfy(&ntfy)) {
> um3_process_mgmt_ntfy(&ntfy);
> }
> while (-1 != m3ua_user_ntfy(&u_ntfy)) {
> um3_process_user_ntfy(&u_ntfy);
> }
> }
> return NULL;
> }
>
> Best Regards,
> Xu Yun
>
>
> -----Original Message-----
> From: Michael Tuexen
> [mailto:Michael.Tuexen AT micmac.franken.de]
> Sent: Tuesday, August 09, 2005 5:30 PM
> To: Xu Yun,SCNB R&D NNC(BJ)
> Cc:
> discussion AT sctp.de
> Subject: Re: [SCTP-Discussion] The difference between ext_sendto() and
> sctp_sendx()
>
> Hi,
>
> see my comments in-line.
>
> Best regards
> Michael
>
> On Aug 9, 2005, at 8:47 Uhr, Xu Yun,SCNB R&D NNC(BJ) wrote:
>
>> Dear all,
>>
>> I'm a very new user of this sctp stack. These days I'm trying to
>> integrate this stack to a m3ua stack (also open source, from
>> sourceforge). Everything looks well when I choose ext_sendto() to send
>> and ext_recvfrom() to receive m3ua messages except the ppid is always
>> '0'. The sctp
> That is within the specification. If you want to specify the PPID you
> should use the sctp_sendmsg call.
>> payload protocol id of M3ua should be '3'. So I turned to use
>> sctp_sendx() and sctp_recvmsg() providing ppid by cmsg, and I met a
>> serious problem: after receiving and sending several m3ua messages,
>> sctp layer starts reporting to receive a message endlessly even after
>> I killed the peer. Could somebody give me some hints? The following is
>> main part of receiving and sending:
>>
>> int m3ua_sendmsg(m3_u32 assoc_id,
>> m3_u32 stream_id,
>> m3_u32 msglen,
>> m3_u8 *pmsg)
>> {
>> int ret;
>> int tid = assoc_table[assoc_id].to;
>> int fid = assoc_table[assoc_id].from;
>> struct sctp_sndrcvinfo info;
>>
>> ....
>>
>> info.sinfo_ppid=3;
>> info.sinfo_stream=0;
>> info.sinfo_assoc_id=0;
>> info.sinfo_timetolive=60000;
>> info.sinfo_flags=MSG_PR_SCTP_TTL;
>>
>> ret = sctp_sendx(from[fid].sockid,pmsg, msglen,(struct
>> sockaddr*)&to[tid].addr,1,&info,0);
> Try sctp_sendmsg instead of sctp_sendx
>>
>> if (-1 == ret) {
>> printf("ERRNO:%d\n", errno);
>> perror("E_sendto_Fail");
>> }
>> return 0;
>> }
>>
>> void* waitfor_message(void *not_used)
>> {
>> int ret;
>> struct timeval timeout;
>> int idx;
>> fd_set rfds;
>> unsigned char msg[1024];
>> unsigned int msglen = 0;
>>
>> timeout.tv_sec = 1;
>> timeout.tv_usec = 0;
>> while(1) {
>> rfds = readfds;
>> ret = ext_select(FD_SETSIZE, &rfds, NULL, NULL, &timeout);
>> if (0 == ret) {
>> timeout.tv_sec = 0;
> Not timeout.tv_sec = 1?
>> timeout.tv_usec = 0;
>> m3timer_ckexpiry(NULL);
>> um3_timer_ckexpiry(NULL);
>> }
>> else if (0 < ret) {
>> for (idx = 0; idx < MAX_LOCAL_EP; idx++)
>> if (1 == from[idx].e_state &&
>>
>> FD_ISSET(from[idx].sockid,&rfds))
>> get_message(idx, from[idx].sockid, msg, &msglen);
>> }
>> else {
>> perror("E_select_Fail");
>> }
>> ...
>> ...
>> }
>> return NULL;
>> }
>>
> After the first timeout of 1 second you will only wait for 0 seconds,
> which means that
> the ext_select call returns immediately. I do not think that this is
> what you want.
>> int get_message( int fid,
>> int sockid,
>> unsigned char msg[1024],
>> unsigned int *pmsglen)
>> {
>> ...
>> struct sockaddr_in addr;
>> int from_len = sizeof(struct sockaddr);
>> struct sctp_sndrcvinfo info;
>> int flags;
>>
>> memset(&addr, 0, sizeof(struct sockaddr));
>>
>> info.sinfo_ppid=3;
>> info.sinfo_stream=0;
>> info.sinfo_assoc_id=0;
>> info.sinfo_timetolive=60000;
>> info.sinfo_flags=MSG_PR_SCTP_TTL;
> You do not have to set ppid and so on at the receiving side. The
> structure will
> be filled in the the SCTP implementation for the received user data.
>>
>> *pmsglen=sctp_recvmsg(sockid,msg,1024,(struct
>>
>> sockaddr*)&addr,&from_len,&info,&flags);
>> if (0 < *pmsglen) {
>> /* search for association for which data is received */
>> ...
>> }
>> return 0;
>> }
>>
>>
>> Thank you in advance!
>>
>> Best Regards,
>> Xu Yun
>> _______________________________________________
>> discussion mailing list
>> discussion AT sctp.de
>> http://www.sctp.de/mailman/listinfo/discussion
>>
>

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• RE: [SCTP-Discussion] The difference between ext_sendto() and sct p_sendx(), Xu Yun,SCNB R&D NNC(BJ), 08/10/2005
  • Re: [SCTP-Discussion] The difference between ext_sendto() and sct p_sendx(), Michael Tuexen, 08/10/2005

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