flow_hash_symmetric_l4(const struct flow *flow, uint32_t basis)
{
    struct {
        union {
            ovs_be32 ipv4_addr;
            struct in6_addr ipv6_addr;
        };
        ovs_be16 eth_type;
        ovs_be16 vlan_tci;
        ovs_be16 tp_port;
        struct eth_addr eth_addr;
        uint8_t ip_proto;
    } fields;

    int i;

    memset(&fields, 0, sizeof fields);
    for (i = 0; i < ARRAY_SIZE(fields.eth_addr.be16); i++) {
        fields.eth_addr.be16[i] = flow->dl_src.be16[i] ^ flow->dl_dst.be16[i];
    }
    fields.vlan_tci = flow->vlan_tci & htons(VLAN_VID_MASK);
    fields.eth_type = flow->dl_type;

    /* UDP source and destination port are not taken into account because they
     * will not necessarily be symmetric in a bidirectional flow. */
    if (fields.eth_type == htons(ETH_TYPE_IP)) {
        fields.ipv4_addr = flow->nw_src ^ flow->nw_dst;
        fields.ip_proto = flow->nw_proto;
        if (fields.ip_proto == IPPROTO_TCP || fields.ip_proto == IPPROTO_SCTP) {
            fields.tp_port = flow->tp_src ^ flow->tp_dst;
        }
    } else if (fields.eth_type == htons(ETH_TYPE_IPV6)) {
        const uint8_t *a = &flow->ipv6_src.s6_addr[0];
        const uint8_t *b = &flow->ipv6_dst.s6_addr[0];
        uint8_t *ipv6_addr = &fields.ipv6_addr.s6_addr[0];

        for (i=0; i<16; i++) {
            ipv6_addr[i] = a[i] ^ b[i];
        }
        fields.ip_proto = flow->nw_proto;
        if (fields.ip_proto == IPPROTO_TCP || fields.ip_proto == IPPROTO_SCTP) {
            fields.tp_port = flow->tp_src ^ flow->tp_dst;
        }
    }
    return jhash_bytes(&fields, sizeof fields, basis);
}
flow_hash_symmetric_l4(const struct flow *flow, uint32_t basis)
{
    struct {
        union {
            ovs_be32 ipv4_addr;
            struct in6_addr ipv6_addr;
        };
        ovs_be16 eth_type;
        ovs_be16 vlan_tci;
        ovs_be16 tp_port;
        struct eth_addr eth_addr;
        uint8_t ip_proto;
    } fields;

    int i;

    memset(&fields, 0, sizeof fields);
    for (i = 0; i < ARRAY_SIZE(fields.eth_addr.be16); i++) {
        fields.eth_addr.be16[i] = flow->dl_src.be16[i] ^ flow->dl_dst.be16[i];
    }
    fields.vlan_tci = flow->vlan_tci & htons(VLAN_VID_MASK);
    fields.eth_type = flow->dl_type;

     
    if (fields.eth_type == htons(ETH_TYPE_IP)) {
        fields.ipv4_addr = flow->nw_src ^ flow->nw_dst;
        fields.ip_proto = flow->nw_proto;
        if (fields.ip_proto == IPPROTO_TCP || fields.ip_proto == IPPROTO_SCTP) {
            fields.tp_port = flow->tp_src ^ flow->tp_dst;
        }
    } else if (fields.eth_type == htons(ETH_TYPE_IPV6)) {
        const uint8_t *a = &flow->ipv6_src.s6_addr[0];
        const uint8_t *b = &flow->ipv6_dst.s6_addr[0];
        uint8_t *ipv6_addr = &fields.ipv6_addr.s6_addr[0];

        for (i=0; i<16; i++) {
            ipv6_addr[i] = a[i] ^ b[i];
        }
        fields.ip_proto = flow->nw_proto;
        if (fields.ip_proto == IPPROTO_TCP || fields.ip_proto == IPPROTO_SCTP) {
            fields.tp_port = flow->tp_src ^ flow->tp_dst;
        }
    }
    return jhash_bytes(&fields, sizeof fields, basis);
}