On Wed, Jun 29, 2022 at 03:28:54PM +0300, Magnus Armholt wrote:
> Strip the IEC62439-3 PRP trailer if it is present
> to support PTP over PRP.
> The implementation is very pedantic about
> trailing bytes and will indicate bad message if the
> PRP trailer bytes are present when parsing the PTP message.
> +static int has_prp_trailer(unsigned char *ptr, int cnt)
> +{
> + if (cnt < PRP_TRAILER_LEN)
> + return -1;
> + //verify suffix first since it is the best identifier
Please use C-style comments.
> + unsigned short suffix_id = ntohs(*(unsigned short*)(ptr + (cnt - 2)));
This seems to be parsing the frame from the end. Couldn't that
randomly match a non-PRP frame, even if you consider the length check
below?
To me it would make more sense to start after the PTP message
according to the messageLength field.
> + if (suffix_id != ETH_P_PRP)
> + return -1;
> +
> + // size should also be verified
> + unsigned short lane_size_field = ntohs(*(unsigned short*)(ptr + (cnt -
> 4)));
Declarations should be at the beginning of the function.
> + // size is lower 12 bits
> + unsigned short lsdu_size = (lane_size_field & 0x0FFF);
> + if (lsdu_size == cnt)
> + return 0;
> +
> + return -1;
> +}
> +
--
Miroslav Lichvar
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