[SCTP] last_sequence_delivered in sctp_process_a_data_chunk question

[Michael Tüxen]

On Dec 15, 2010, at 8:46 AM, 罗钰 wrote:

> Hi, all experts:    I find a suspect point in function of sctp_process_a_data_chunk in all FreeBSD branches.for example:Line 1900 of sctp_indata: (asoc->strmin[strmno].last_sequence_delivered + 1) == strmseqThis is a logical judgement sentence.last_sequence_delivered is unsigned short type, strmseq is also.there is a problem: if last_sequence_delivered equal 0xffff, and the result of last_sequence_delivered + 1 must be 0x10000, rather than 0x0000, and if strmseq is also be 0x0, then this judgement will give you wrong value.
> so i think  put a (uint16_t) before this sentence will be more secure. so how do you think?like this: (uint16_t)(asoc->strmin[strmno].last_sequence_delivered + 1) == strmseqThanks and i hope your response.
In head and FreeBSD 8.0 and 8.1 sctp_structs.h contains:
struct sctp_stream_in {
	struct sctp_readhead inqueue;
	uint16_t stream_no;
	uint16_t last_sequence_delivered;	/* used for re-order */
	uint8_t  delivery_started;
};

Furthermore sctp_process_a_data_chunk() contains:
	uint16_t strmno, strmseq;

So I do not think the problem "is in all branches". Can you be more specific,
which version your are talking about?

Best regards
Michael
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