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Make TAP devices usable in normal traffic scenarios #649

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Merged
guvenc merged 2 commits into from
Mar 11, 2025
Merged

Make TAP devices usable in normal traffic scenarios #649

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7d5ff20
Calculate nat packet checksum manually for TAP devices
guvenc Feb 24, 2025
b39a89b
Accept own MAC for PF neighbour in case of TAP device
guvenc Mar 10, 2025
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6 changes: 6 additions & 0 deletions include/dp_port.h
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Original file line number Diff line number Diff line change
Expand Up @@ -196,6 +196,12 @@ struct dp_port *dp_get_port_by_pf_index(uint16_t index)
return index < RTE_DIM(_dp_pf_ports) ? _dp_pf_ports[index] : NULL;
}

static __rte_always_inline
bool dp_conf_is_tap_mode(void)
{
return dp_conf_get_nic_type() == DP_CONF_NIC_TYPE_TAP;
}

#ifdef __cplusplus
}
#endif
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20 changes: 15 additions & 5 deletions src/dp_nat.c
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Expand Up @@ -268,10 +268,10 @@ void dp_nat_chg_ip(struct dp_flow *df, struct rte_ipv4_hdr *ipv4_hdr,
{
struct rte_udp_hdr *udp_hdr;
struct rte_tcp_hdr *tcp_hdr;
bool is_tap = dp_conf_is_tap_mode();

ipv4_hdr->hdr_checksum = 0;
m->ol_flags |= RTE_MBUF_F_TX_IPV4;
m->ol_flags |= RTE_MBUF_F_TX_IP_CKSUM;
m->tx_offload = 0;
m->l2_len = sizeof(struct rte_ether_hdr);
m->l3_len = rte_ipv4_hdr_len(ipv4_hdr);
Expand All @@ -280,22 +280,32 @@ void dp_nat_chg_ip(struct dp_flow *df, struct rte_ipv4_hdr *ipv4_hdr,
switch (df->l4_type) {
case IPPROTO_TCP:
tcp_hdr = (struct rte_tcp_hdr *)(ipv4_hdr + 1);
tcp_hdr->cksum = 0;
m->ol_flags |= RTE_MBUF_F_TX_TCP_CKSUM;
m->l4_len = DP_TCP_HDR_LEN(tcp_hdr);
tcp_hdr->cksum = 0;
if (unlikely(is_tap))
tcp_hdr->cksum = rte_ipv4_udptcp_cksum(ipv4_hdr, tcp_hdr);
else
m->ol_flags |= RTE_MBUF_F_TX_TCP_CKSUM;
break;
case IPPROTO_UDP:
udp_hdr = (struct rte_udp_hdr *)(ipv4_hdr + 1);
udp_hdr->dgram_cksum = 0;
m->ol_flags |= RTE_MBUF_F_TX_UDP_CKSUM;
m->l4_len = sizeof(struct rte_udp_hdr);
udp_hdr->dgram_cksum = 0;
if (unlikely(is_tap))
udp_hdr->dgram_cksum = rte_ipv4_udptcp_cksum(ipv4_hdr, udp_hdr);
else
m->ol_flags |= RTE_MBUF_F_TX_UDP_CKSUM;
break;
case IPPROTO_ICMP:
m->l4_len = sizeof(struct rte_icmp_hdr);
break;
default:
break;
}
if (unlikely(is_tap))
ipv4_hdr->hdr_checksum = rte_ipv4_cksum(ipv4_hdr);
else
m->ol_flags |= RTE_MBUF_F_TX_IP_CKSUM;
}

static void dp_calculate_icmp_checksum(struct rte_icmp_hdr *icmp_hdr, size_t icmp_len)
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4 changes: 4 additions & 0 deletions src/dp_netlink.c
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Expand Up @@ -13,6 +13,7 @@
#include "dp_log.h"
#include "dp_netlink.h"
#include "dp_util.h"
#include "dp_port.h"

static int dp_read_neigh(struct nlmsghdr *nh, __u32 nll, struct rte_ether_addr *neigh,
const struct rte_ether_addr *own_mac)
Expand All @@ -33,6 +34,9 @@ static int dp_read_neigh(struct nlmsghdr *nh, __u32 nll, struct rte_ether_addr *
if (rt_attr->rta_type == NDA_LLADDR)
memcpy(&neigh->addr_bytes, RTA_DATA(rt_attr), sizeof(neigh->addr_bytes));
}
// If it is a tap device, we make an exception with own MAC address check. FeBOX case
if (dp_conf_is_tap_mode())
return DP_OK;
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@PlagueCZ PlagueCZ Mar 11, 2025

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Ooh nice solution. So basically for TAP you accept the own mac here as you wanted and if we ever need a true neighbor mac it can be easily changed here, right?

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@guvenc guvenc Mar 11, 2025

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This would already accept true neighbor MAC. It just can not differentiate the "error case" anymore when it is in TAP mode. (Error case being "the router sending TAP device MAC as router MAC")

if (!DP_MAC_EQUAL(own_mac, neigh))
return DP_OK;
}
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