On 3/16/21 9:12 AM, Bin Meng wrote:
> Add a helper to pad a short ethernet frame to the minimum required
> length, which can be used by backend codes.
>
> Signed-off-by: Bin Meng <[email protected]>
>
> ---
>
> Changes in v3:
> - use 'without' instead of 'sans'
> - add a helper to pad short frames
>
> include/net/eth.h | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
> diff --git a/include/net/eth.h b/include/net/eth.h
> index 0671be6916..bc064f8e52 100644
> --- a/include/net/eth.h
> +++ b/include/net/eth.h
> @@ -31,6 +31,31 @@
>
> #define ETH_ALEN 6
> #define ETH_HLEN 14
> +#define ETH_ZLEN 60 /* Min. octets in frame without FCS */
> +
> +/**
> + * pad_short_frame - pad a short frame to the minimum ethernet frame length
> + *
> + * If the ethernet frame size is shorter than 60 bytes, it will be padded to
> + * 60 bytes at the address @min_pkt.
> + *
> + * @min_pkt: buffer address to hold the padded frame
> + * @pkt: address to hold the original ethernet frame
> + * @size: size of the original ethernet frame
> + * @return true if the frame is padded, otherwise false
> + */
> +static inline bool pad_short_frame(uint8_t *min_pkt, const uint8_t *pkt,
> + int size)
> +{
> + if (size < ETH_ZLEN) {
> + /* pad to minimum ethernet frame length */
> + memcpy(min_pkt, pkt, size);
> + memset(&min_pkt[size], 0, ETH_ZLEN - size);
> + return true;
> + }
> +
> + return false;
> +}
I don't want to be too nitpicky but since I'm Cc'ed...
- 'ethernet' -> 'Ethernet'
- I'm not sure inlining is justified
- The same function is used for 2 different operations,
. check if padding is required
. do the padding
- If we provide a function a buffer to fill, we need to check the
buffer size is big enough to avoid overflow
What about something like:
bool pad_short_frame(char *padded_pkt, size_t *padded_buflen,
const void *pkt, size_t pkt_size);
{
assert(padded_buflen && *padded_buflen >= ETH_ZLEN);
if (src_size >= ETH_ZLEN) {
return false;
}
/* pad to minimum ethernet frame length */
memcpy(padded_pkt, pkt, pkt_size);
memset(&padded_pkt[pkt_size], 0, ETH_ZLEN - padded_buflen);
*padded_buflen = ETH_ZLEN;
return true;
}
What do you think?
