On 8/21/20 2:32 PM, Michael Pfeiffer wrote:
> Currently, rte_ipv4_cksum() and rte_ipv4_udptcp_cksum() assume all IPv4
> headers have sizeof(struct rte_ipv4_hdr) bytes. This is not true for
> those (rare) packets with IPv4 options. Thus, both IPv4 and TCP/UDP
> checksums are calculated wrong.
>
> This patch fixes the issue by using the actual IPv4 header length from
> the packet's IHL field.
>
> Signed-off-by: Michael Pfeiffer <michael.pfeif...@tu-ilmenau.de>
> ---
> lib/librte_net/rte_ip.h | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/lib/librte_net/rte_ip.h b/lib/librte_net/rte_ip.h
> index fcd1eb342..6c3ff2603 100644
> --- a/lib/librte_net/rte_ip.h
> +++ b/lib/librte_net/rte_ip.h
> @@ -269,7 +269,7 @@ static inline uint16_t
> rte_ipv4_cksum(const struct rte_ipv4_hdr *ipv4_hdr)
> {
> uint16_t cksum;
> - cksum = rte_raw_cksum(ipv4_hdr, sizeof(struct rte_ipv4_hdr));
> + cksum = rte_raw_cksum(ipv4_hdr, (ipv4_hdr->version_ihl & 0xf) * 4);
> return (uint16_t)~cksum;
> }
>
> @@ -311,7 +311,7 @@ rte_ipv4_phdr_cksum(const struct rte_ipv4_hdr *ipv4_hdr,
> uint64_t ol_flags)
> } else {
> psd_hdr.len = rte_cpu_to_be_16(
> (uint16_t)(rte_be_to_cpu_16(ipv4_hdr->total_length)
> - - sizeof(struct rte_ipv4_hdr)));
> + - ((ipv4_hdr->version_ihl & 0xf) * 4)));
> }
> return rte_raw_cksum(&psd_hdr, sizeof(psd_hdr));
> }
> @@ -319,8 +319,8 @@ rte_ipv4_phdr_cksum(const struct rte_ipv4_hdr *ipv4_hdr,
> uint64_t ol_flags)
> /**
> * Process the IPv4 UDP or TCP checksum.
> *
> - * The IPv4 header should not contains options. The IP and layer 4
> - * checksum must be set to 0 in the packet by the caller.
> + * The IP and layer 4 checksum must be set to 0 in the packet by
> + * the caller.
> *
> * @param ipv4_hdr
> * The pointer to the contiguous IPv4 header.
> @@ -339,7 +339,7 @@ rte_ipv4_udptcp_cksum(const struct rte_ipv4_hdr
> *ipv4_hdr, const void *l4_hdr)
> if (l3_len < sizeof(struct rte_ipv4_hdr))
> return 0;
>
> - l4_len = l3_len - sizeof(struct rte_ipv4_hdr);
> + l4_len = l3_len - ((ipv4_hdr->version_ihl & 0xf) * 4);
Previous if condition guarantees that the result will be not
negative (and make huge l4_len), so it looks like it should be
updated as well. I think it makes sense to introduce
additional variable with calculated IPv4 header length.
>
> cksum = rte_raw_cksum(l4_hdr, l4_len);
> cksum += rte_ipv4_phdr_cksum(ipv4_hdr, 0);
>
