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Re: [PATCH v4 01/12] net: eth: Add a helper to pad a short Ethernet fram
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [PATCH v4 01/12] net: eth: Add a helper to pad a short Ethernet frame |
Date: |
Tue, 16 Mar 2021 16:09:07 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 |
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;
> +}
>
- [PATCH v4 00/12] net: Pad short frames for network backends, Bin Meng, 2021/03/16
- [PATCH v4 01/12] net: eth: Add a helper to pad a short Ethernet frame, Bin Meng, 2021/03/16
- Re: [PATCH v4 01/12] net: eth: Add a helper to pad a short Ethernet frame,
Philippe Mathieu-Daudé <=
- [PATCH v4 02/12] net: Add a 'do_not_pad" to NetClientState, Bin Meng, 2021/03/16
- [PATCH v4 03/12] net: Pad short frames to minimum size before sending from SLiRP/TAP, Bin Meng, 2021/03/16
- [PATCH v4 04/12] hw/net: virtio-net: Initialize nc->do_not_pad to true, Bin Meng, 2021/03/16
- [PATCH v4 05/12] hw/net: e1000: Remove the logic of padding short frames in the receive path, Bin Meng, 2021/03/16
- [PATCH v4 06/12] hw/net: vmxnet3: Remove the logic of padding short frames in the receive path, Bin Meng, 2021/03/16
- [PATCH v4 07/12] hw/net: i82596: Remove the logic of padding short frames in the receive path, Bin Meng, 2021/03/16
- [PATCH v4 08/12] hw/net: ne2000: Remove the logic of padding short frames in the receive path, Bin Meng, 2021/03/16
- [PATCH v4 09/12] hw/net: pcnet: Remove the logic of padding short frames in the receive path, Bin Meng, 2021/03/16