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net: eth: Add a helper to pad a short Ethernet frame

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Add a helper to pad a short Ethernet frame to the minimum required
length, which can be used by backends' code.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
This commit is contained in:
Bin Meng 2021-03-17 14:26:27 +08:00 committed by Jason Wang
parent bdee969c0e
commit af774513f7
2 changed files with 34 additions and 0 deletions
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17
include/net/eth.h
View File

@ -31,6 +31,7 @@
#define ETH_ALEN 6 #define ETH_ALEN 6
#define ETH_HLEN 14 #define ETH_HLEN 14
#define ETH_ZLEN 60 /* Min. octets in frame without FCS */
struct eth_header { struct eth_header {
uint8_t h_dest[ETH_ALEN]; /* destination eth addr */ 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, eth_parse_ipv6_hdr(const struct iovec *pkt, int pkt_frags,
size_t ip6hdr_off, eth_ip6_hdr_info *info); 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: pointer holding length of @padded_pkt. If the frame is
* padded, the length will be updated to the padded one.
* @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 #endif

17
net/eth.c
View File

@ -548,3 +548,20 @@ bool eth_parse_ipv6_hdr(const struct iovec *pkt, int pkt_frags,
info->l4proto = ext_hdr.ip6r_nxt; info->l4proto = ext_hdr.ip6r_nxt;
return true; 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;
}