On Wed, Jan 18, 2017 at 3:15 AM, Xin Long <lucien.xin@xxxxxxxxx> wrote: > On Wed, Jan 18, 2017 at 2:57 AM, Julian Cordes <julian.cordes@xxxxxxxxx> wrote: >> 2017-01-17 19:49 GMT+01:00 Xin Long <lucien.xin@xxxxxxxxx>: >>> On Tue, Jan 17, 2017 at 9:13 PM, Julian Cordes <julian.cordes@xxxxxxxxx> wrote: >>>> When fragmented ordered user messages are sent to the linux kernel user >>>> messages with inconsistent stream sequence numbers are accepted and >>>> delivered to the application. Take for example an look at the following test case: >>>> https://github.com/nplab/PR_SCTP_Testsuite/blob/master/forward-tsn/error-cases/packet-loss/ordered/ordered-packet-loss-2.pkt >>>> >>>> Here I first inject two DATA-Chunks with sid/ssn 1/1, 2/1 into the >>>> kernel with packetdrill: >>>> line 67: +0.0 < sctp: DATA[flgs=E, len=1016, tsn=2, sid=1, ssn=1, >>>> ppid=0] >>>> line 69: +0.1 < sctp: DATA[flgs=E, len=1016, tsn=4, sid=2, ssn=1, >>>> ppid=0] >>>> >>>> After 0.1 seconds i then inject an FORWARD-TSN with cum_tsn=2 bundled >>>> with an DATA-Chunk that looks like this: >>>> DATA[flgs=B, len=1016, tsn=3, sid=2, ssn=0, ppid=0] >>>> >>>> This "looks" like the first segment of the user message where already a >>>> fragment (tsn=4) was received. But the ssn-values are not consistent. >>>> The DATA-Chunk with tsn=3 has ssn=0 and the ssn=1 therefore they should >>>> be ignored by the IUT and not be delivered to the userland application when >>>> calling sctp_recvmsg. Unfortunatly the linux kernel implementation does >>>> currently deliver these inconsistent user messages. >>> sorry, I may misunderstand you. >>> >>> after FORWARD-TSN, "DATA[flgs=E, len=1016, tsn=2, sid=1, ssn=1" >>> should be received, then only "sctp: DATA[flgs=E, len=1016, tsn=4, >>> sid=2, ssn=1" is in the queue, then "DATA[flgs=B, len=1016, tsn=3, >>> sid=2, ssn=0, ppid=0]" is processed, these two chunks (tsn=3 and >>> tsn=4) should be recvmsg, as their sid are the same and ssn are >>> consistent (ssn=0 and ssn=1). >>> and your sctp_recvmsg is after above, so it should be right. >>> >>> did I miss something? >>> >>> >> Shouldnt the ssn be 0 for both DATA-Chunks with sid=2, because they >> consistent to the same first fragmented user message of stream with >> sid=2? > ahh, got you now, will look into it tomorrow, thanks. > linux sctp now doesn't yet support "interleave", it believes the chunks / fragmenteds from the same msg have continuous / consistent TSNs. That's why it can ignore the ssn and only care about tsn and flag when reasm fragmenteds. we will improve it when implementing "interleave" soon, thanks for reporting. >>>> >>>> There are many test-cases that all reproduce this >>>> issue. Just take a look at the README at >>>> https://github.com/nplab/PR_SCTP_Testsuite/tree/master/forward-tsn/error-cases/packet-loss/ordered. -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
