> From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Ferruh Yigit > Sent: Tuesday, November 10, 2020 3:47 PM > > On 11/9/2020 2:22 PM, Michael Pfeiffer wrote: > > Unlike TCP, UDP checksums are optional and may be zero to indicate "not > > set" [RFC 768] (except for IPv6, where this prohibited [RFC 8200]). Add > > this special case to the checksum offload emulation in net/tap. > > > > Signed-off-by: Michael Pfeiffer <michael.pfeif...@tu-ilmenau.de> > > --- > > drivers/net/tap/rte_eth_tap.c | 13 +++++++++++-- > > 1 file changed, 11 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/net/tap/rte_eth_tap.c > b/drivers/net/tap/rte_eth_tap.c > > index 2f8abb12c..e486b41c5 100644 > > --- a/drivers/net/tap/rte_eth_tap.c > > +++ b/drivers/net/tap/rte_eth_tap.c > > @@ -303,6 +303,7 @@ tap_verify_csum(struct rte_mbuf *mbuf) > > uint16_t cksum = 0; > > void *l3_hdr; > > void *l4_hdr; > > + struct rte_udp_hdr *udp_hdr; > > > > if (l2 == RTE_PTYPE_L2_ETHER_VLAN) > > l2_len += 4; > > @@ -349,10 +350,18 @@ tap_verify_csum(struct rte_mbuf *mbuf) > > /* Don't verify checksum for multi-segment packets. */ > > if (mbuf->nb_segs > 1) > > return; > > - if (l3 == RTE_PTYPE_L3_IPV4) > > + if (l3 == RTE_PTYPE_L3_IPV4) { > > + if (l4 == RTE_PTYPE_L4_UDP) { > > + udp_hdr = (struct rte_udp_hdr *)l4_hdr; > > + if (udp_hdr->dgram_cksum == 0) { > > + mbuf->ol_flags |= PKT_RX_L4_CKSUM_NONE; > > + return; > > + } > > + } > > cksum = ~rte_ipv4_udptcp_cksum(l3_hdr, l4_hdr); > > - else if (l3 == RTE_PTYPE_L3_IPV6) > > + } else if (l3 == RTE_PTYPE_L3_IPV6) { > > cksum = ~rte_ipv6_udptcp_cksum(l3_hdr, l4_hdr); > > + } > > mbuf->ol_flags |= cksum ? > > PKT_RX_L4_CKSUM_BAD : > > PKT_RX_L4_CKSUM_GOOD; > > > > While checking this I stuck with following part: > > cksum = ~rte_ipv6_udptcp_cksum(l3_hdr, l4_hdr); > ... > mbuf->ol_flags |= cksum ? > PKT_RX_L4_CKSUM_BAD : > PKT_RX_L4_CKSUM_GOOD; > > > Is this correct, or am I missing something, can intention be '!' here > instead of > '~' ?
It is correct. The packet's checksum is calculated by rte_ipv6_udptcp_cksum(), and it should be 0xFFFF. The '~' operation makes cksum 0 iff the calculated checksum is 0xFFFF.
