| Message ID | 20210316081254.72684-2-bmeng.cn@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | net: Pad short frames for network backends | expand |
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 <bmeng.cn@gmail.com> > > --- > > 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?
On Tue, Mar 16, 2021 at 4:49 PM Philippe Mathieu-Daudé <philmd@redhat.com> wrote: > > 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 <bmeng.cn@gmail.com> > > > > --- > > > > 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? Looks good to me. Will update in the next version. Regards, Bin
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; +} struct eth_header { uint8_t h_dest[ETH_ALEN]; /* destination eth addr */
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 <bmeng.cn@gmail.com> --- 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(+)