[Qemu-devel] Re: [PATCH v2] [slirp] Make ARP replies at least 64 bytes long

[Michael S. Tsirkin]

On Wed, Sep 15, 2010 at 10:33:26PM +0200, Hervé Poussineau wrote:
> IEEE 802.3 standard requires Ethernet frames to be at least 64 bytes long.
> If it is not the case, they will be considered as runt frames, and may be 
> ignored by netcard and/or OS
> 
> Signed-off-by: Hervé Poussineau <address@hidden>

IMO slirp is not the best place for this, e.g. virtio-net
does not need the padding. 

> ---
>  slirp/slirp.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/slirp/slirp.c b/slirp/slirp.c
> index 82fd9b4..332d83b 100644
> --- a/slirp/slirp.c
> +++ b/slirp/slirp.c
> @@ -599,7 +599,7 @@ static void arp_input(Slirp *slirp, const uint8_t *pkt, 
> int pkt_len)
>  {
>      struct ethhdr *eh = (struct ethhdr *)pkt;
>      struct arphdr *ah = (struct arphdr *)(pkt + ETH_HLEN);
> -    uint8_t arp_reply[ETH_HLEN + sizeof(struct arphdr)];
> +    uint8_t arp_reply[max(ETH_HLEN + sizeof(struct arphdr), 64)];
>      struct ethhdr *reh = (struct ethhdr *)arp_reply;
>      struct arphdr *rah = (struct arphdr *)(arp_reply + ETH_HLEN);
>      int ar_op;
> @@ -619,6 +619,7 @@ static void arp_input(Slirp *slirp, const uint8_t *pkt, 
> int pkt_len)
>              }
>              return;
>          arp_ok:
> +            memset(arp_reply, 0, sizeof(arp_reply));
>              /* XXX: make an ARP request to have the client address */
>              memcpy(slirp->client_ethaddr, eh->h_source, ETH_ALEN);
>  
> -- 
> 1.7.1.GIT
>