On Mon, Aug 1, 2022 at 12:12 PM Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> On Tue, Jul 26, 2022 at 11:48 AM Joanne Koong <joannelkoong@xxxxxxxxx> wrote:
> >
> >
> > -static __always_inline int handle_ipv4(struct xdp_md *xdp)
> > +static __always_inline int handle_ipv4(struct xdp_md *xdp, struct bpf_dynptr *xdp_ptr)
> > {
> > - void *data_end = (void *)(long)xdp->data_end;
> > - void *data = (void *)(long)xdp->data;
> > + struct bpf_dynptr new_xdp_ptr;
> > struct iptnl_info *tnl;
> > struct ethhdr *new_eth;
> > struct ethhdr *old_eth;
> > - struct iphdr *iph = data + sizeof(struct ethhdr);
> > + struct iphdr *iph;
> > __u16 *next_iph;
> > __u16 payload_len;
> > struct vip vip = {};
> > @@ -90,10 +90,12 @@ static __always_inline int handle_ipv4(struct xdp_md *xdp)
> > __u32 csum = 0;
> > int i;
> >
> > - if (iph + 1 > data_end)
> > + iph = bpf_dynptr_data(xdp_ptr, ethhdr_sz,
> > + iphdr_sz + (tcphdr_sz > udphdr_sz ? tcphdr_sz : udphdr_sz));
> > + if (!iph)
> > return XDP_DROP;
>
> dynptr based xdp/skb access looks neat.
> Maybe in addition to bpf_dynptr_data() we can add helper(s)
> that return skb/xdp_md from dynptr?
> This way the code will be passing dynptr only and there will
> be no need to pass around 'struct xdp_md *xdp' (like this function).
Great idea! I'll add this to v2.
>
> Separately please keep the existing tests instead of converting them.
> Either ifdef data/data_end vs dynptr style or copy paste
> the whole test into a new .c file. Whichever is cleaner.
Will do for v2.
