本文讨论了FreeBSD中SCTP协议处理数据包时可能出现的问题，特别是当last_sequence_delivered为0xFFFF时，加1操作可能导致类型转换错误。提出了一种解决方案，通过类型强制转换来避免此问题。
> > > Hi, thanks response quickly!
> > > I thank maybe i did't say more clear. I mean that last_sequence_delivered and strmseq are uint16_t type in all FreeBSD branches.
> > > my worry is that:if last_sequence_delivered equal 0xFFFF, then the following compare sentence will cause some error:
> > > if ((asoc->strmin[strmno].last_sequence_delivered + 1) == strmseq)
> > > .........
> > > this sentence is in sctp_process_a_data_chunk of FB.
> > > because compiler will scale last_sequence_delivered to 32 bit when add 1, if last_sequence_delivered equal 0xFFFF, then (asoc->strmin[strmno].last_sequence_delivered + 1) will be 0x10000, rather than 0x0.
> > > so i think we should add a type_cast before the sentence like this:
> > > I thank maybe i did't say more clear. I mean that last_sequence_delivered and strmseq are uint16_t type in all FreeBSD branches.
> > > my worry is that:if last_sequence_delivered equal 0xFFFF, then the following compare sentence will cause some error:
> > > if ((asoc->strmin[strmno].last_sequence_delivered + 1) == strmseq)
> > > .........
> > > this sentence is in sctp_process_a_data_chunk of FB.
> > > because compiler will scale last_sequence_delivered to 32 bit when add 1, if last_sequence_delivered equal 0xFFFF, then (asoc->strmin[strmno].last_sequence_delivered + 1) will be 0x10000, rather than 0x0.
> > > so i think we should add a type_cast before the sentence like this:
> > > if ((uint16_t)(asoc->strmin[strmno].last_sequence_delivered + 1) == strmseq)
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