| Message ID | 20210316120420.19658-2-bmeng.cn@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | net: Pad short frames for network backends | expand |
On 3/16/21 1:04 PM, Bin Meng wrote: > Add a helper to pad a short Ethernet frame to the minimum required > length, which can be used by backend codes. "backend codes" sounds odd but I'm not native English speaker. I'd have used "backends' code" instead... > Signed-off-by: Bin Meng <bmeng.cn@gmail.com> > > --- > > Changes in v4: > - change 'ethernet' to 'Ethernet' > - do not inline the helper > - check the padded buffer size to avoid buffer overflow > > Changes in v3: > - use 'without' instead of 'sans' > - add a helper to pad short frames > > include/net/eth.h | 17 +++++++++++++++++ > net/eth.c | 17 +++++++++++++++++ > 2 files changed, 34 insertions(+) > > diff --git a/include/net/eth.h b/include/net/eth.h > index 0671be6916..6aabbdd0d3 100644 > --- a/include/net/eth.h > +++ b/include/net/eth.h > @@ -31,6 +31,7 @@ > > #define ETH_ALEN 6 > #define ETH_HLEN 14 > +#define ETH_ZLEN 60 /* Min. octets in frame without FCS */ > > struct eth_header { > uint8_t h_dest[ETH_ALEN]; /* destination eth addr */ > @@ -422,4 +423,20 @@ bool > eth_parse_ipv6_hdr(const struct iovec *pkt, int pkt_frags, > size_t ip6hdr_off, eth_ip6_hdr_info *info); > > +/** > + * eth_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 @padded_pkt. > + * > + * @padded_pkt: buffer address to hold the padded frame > + * @padded_buflen: buffer length of @padded_pkt. If the frame is padded, it is > + * written to ETH_ZLEN, otherwise it remains unchanged. @padded_buflen: pointer holding length of @padded_pkt. If the frame is padded, the length will be updated to the padded one. Otherwise: Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> (since you describe frames, maybe s/pkt/frame/?) > + * @pkt: address to hold the original Ethernet frame > + * @pkt_size: size of the original Ethernet frame > + * @return true if the frame is padded, otherwise false > + */ > +bool eth_pad_short_frame(uint8_t *padded_pkt, size_t *padded_buflen, > + const void *pkt, size_t pkt_size); > + > #endif > diff --git a/net/eth.c b/net/eth.c > index 1e0821c5f8..f913e4396f 100644 > --- a/net/eth.c > +++ b/net/eth.c > @@ -548,3 +548,20 @@ bool eth_parse_ipv6_hdr(const struct iovec *pkt, int pkt_frags, > info->l4proto = ext_hdr.ip6r_nxt; > return true; > } > + > +bool eth_pad_short_frame(uint8_t *padded_pkt, size_t *padded_buflen, > + const void *pkt, size_t pkt_size) > +{ > + assert(padded_buflen && *padded_buflen >= ETH_ZLEN); > + > + if (pkt_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 - pkt_size); > + *padded_buflen = ETH_ZLEN; > + > + return true; > +} >
On Tue, Mar 16, 2021 at 11:09 PM Philippe Mathieu-Daudé <philmd@redhat.com> wrote: > > On 3/16/21 1:04 PM, Bin Meng wrote: > > Add a helper to pad a short Ethernet frame to the minimum required > > length, which can be used by backend codes. > > "backend codes" sounds odd but I'm not native English speaker. > I'd have used "backends' code" instead... > Will update in v5. > > Signed-off-by: Bin Meng <bmeng.cn@gmail.com> > > > > --- > > > > Changes in v4: > > - change 'ethernet' to 'Ethernet' > > - do not inline the helper > > - check the padded buffer size to avoid buffer overflow > > > > Changes in v3: > > - use 'without' instead of 'sans' > > - add a helper to pad short frames > > > > include/net/eth.h | 17 +++++++++++++++++ > > net/eth.c | 17 +++++++++++++++++ > > 2 files changed, 34 insertions(+) > > > > diff --git a/include/net/eth.h b/include/net/eth.h > > index 0671be6916..6aabbdd0d3 100644 > > --- a/include/net/eth.h > > +++ b/include/net/eth.h > > @@ -31,6 +31,7 @@ > > > > #define ETH_ALEN 6 > > #define ETH_HLEN 14 > > +#define ETH_ZLEN 60 /* Min. octets in frame without FCS */ > > > > struct eth_header { > > uint8_t h_dest[ETH_ALEN]; /* destination eth addr */ > > @@ -422,4 +423,20 @@ bool > > eth_parse_ipv6_hdr(const struct iovec *pkt, int pkt_frags, > > size_t ip6hdr_off, eth_ip6_hdr_info *info); > > > > +/** > > + * eth_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 @padded_pkt. > > + * > > + * @padded_pkt: buffer address to hold the padded frame > > + * @padded_buflen: buffer length of @padded_pkt. If the frame is padded, it is > > + * written to ETH_ZLEN, otherwise it remains unchanged. > > @padded_buflen: pointer holding length of @padded_pkt. If the frame is > padded, the length will be updated to the padded one. Will update in v5. > > Otherwise: > Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> > > (since you describe frames, maybe s/pkt/frame/?) > By looking at the existing codes, 'pkt' seems to be a common variable name representing ethernet frames, hence I will keep this as it is. Regards, Bin
diff --git a/include/net/eth.h b/include/net/eth.h index 0671be6916..6aabbdd0d3 100644 --- a/include/net/eth.h +++ b/include/net/eth.h @@ -31,6 +31,7 @@ #define ETH_ALEN 6 #define ETH_HLEN 14 +#define ETH_ZLEN 60 /* Min. octets in frame without FCS */ struct eth_header { uint8_t h_dest[ETH_ALEN]; /* destination eth addr */ @@ -422,4 +423,20 @@ bool eth_parse_ipv6_hdr(const struct iovec *pkt, int pkt_frags, size_t ip6hdr_off, eth_ip6_hdr_info *info); +/** + * eth_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 @padded_pkt. + * + * @padded_pkt: buffer address to hold the padded frame + * @padded_buflen: buffer length of @padded_pkt. If the frame is padded, it is + * written to ETH_ZLEN, otherwise it remains unchanged. + * @pkt: address to hold the original Ethernet frame + * @pkt_size: size of the original Ethernet frame + * @return true if the frame is padded, otherwise false + */ +bool eth_pad_short_frame(uint8_t *padded_pkt, size_t *padded_buflen, + const void *pkt, size_t pkt_size); + #endif diff --git a/net/eth.c b/net/eth.c index 1e0821c5f8..f913e4396f 100644 --- a/net/eth.c +++ b/net/eth.c @@ -548,3 +548,20 @@ bool eth_parse_ipv6_hdr(const struct iovec *pkt, int pkt_frags, info->l4proto = ext_hdr.ip6r_nxt; return true; } + +bool eth_pad_short_frame(uint8_t *padded_pkt, size_t *padded_buflen, + const void *pkt, size_t pkt_size) +{ + assert(padded_buflen && *padded_buflen >= ETH_ZLEN); + + if (pkt_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 - pkt_size); + *padded_buflen = ETH_ZLEN; + + return true; +}
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 v4: - change 'ethernet' to 'Ethernet' - do not inline the helper - check the padded buffer size to avoid buffer overflow Changes in v3: - use 'without' instead of 'sans' - add a helper to pad short frames include/net/eth.h | 17 +++++++++++++++++ net/eth.c | 17 +++++++++++++++++ 2 files changed, 34 insertions(+)