Key parsing in the OvS

OVS在处理每条流的时候，先根据每条流生产相应的key，然后根据key匹配相应的流表，根据流表中的action操作来处理每条流，本文对key的结构体进行分析，看看对于一条流会提出那些特征信息。对于key的描述在openvswitch源码中的flow.h文件中。

struct Sw_flow_key {U8 tun_opts[255];    U8 Tun_opts_len;  struct Ip_tunnel_key tun_key; /* Encapsulating tunnel key.   */struct {U32 priority; /* Packet QoS priority.   */U32 Skb_mark; /* SKB mark.    */U16 In_port; /* Input switch port (or dp_max_ports). */} __packed PHY; /* Safe when right after ' Tun_key '.           */U8 Mac_proto; /* MAC layer protocol (e.g. Ethernet).                   */U8 Tun_proto; /* Protocol of encapsulating Tunnel.      */U32 Ovs_flow_hash;  /* Datapath computed hash value.          */U32 recirc_id;  /* recirculation ID.   */struct {U8 Src[eth_alen]; /* Ethernet Source address.   */U8 Dst[eth_alen]; /* Ethernet Destination address.        */struct Vlan_head VLAN;        struct Vlan_head Cvlan;        __BE16 type; /* Ethernet frame type.    */} ETH; /* Filling a hole of bytes.    */U8 Ct_state;       U8 Ct_orig_proto;       /* CT Original direction tuple IP              * protocol.        */Union {struct {__be32 top_lse;/* Top Label Stack entry */} MPLS;   struct {U8 proto; /* IP protocol or lower 8 bits of ARP opcode.     */U8 TOS; /* IP ToS.     */U8 TTL; /* IP ttl/hop limit.    */U8 Frag; /* One of ovs_frag_type_*.    */} IP;    };            U16 Ct_zone; /* Conntrack zone.     */struct {__be16 src; /* TCP/UDP/SCTP Source port.     */__BE16 DST; /* TCP/UDP/SCTP Destination port.       */__BE16 flags; /* TCP flags.    */} TP;  Union {struct {struct {__be32 src;/* IP source address. */__BE32 DST; /* IP Destination address.            */} addr;                    Union {struct {__be32 src;                __BE32 DST;  } Ct_orig; /* Conntrack original direction fields.                */struct {U8 Sha[eth_alen]; /* ARP source hardware address.   */U8 Tha[eth_alen]; /* ARP target hardware address.            */} ARP;        };        } IPv4;    struct {struct {struct in6_addr src; /* IPV6 Source address.    */struct IN6_ADDR DST; /* IPv6 Destination address.            */} addr;           __BE32 label; /* IPv6 Flow label.                    */Union {struct {struct in6_addr src;                struct IN6_ADDR DST;  } Ct_orig; /* Conntrack original direction fields. */struct {struct IN6_ADDR target;/* ND target address. */U8 Sll[e   Th_alen]; /* ND Source link Layer address.   */U8 Tll[eth_alen]; /* ND target link Layer address.            */} nd;        };    } IPv6;    }; struct {/* Connection tracking fields NoT packed above. */struct {__be16 src;/* ct orig tuple tp src port. */__BE16 DST;/* CT orig tuple TP DST Port.        */} ORIG_TP;        U32 Mark;    struct Ovs_key_ct_labels labels; } CT;};

struct ip_tunnel_key {    __be64          tun_id;    union {        struct {            __be32  src;            __be32  dst;        } ipv4;        struct {            struct in6_addr src;            struct in6_addr dst;        } ipv6;    } u;    __be16          tun_flags;    u8          tos;        /* TOS for IPv4, TC for IPv6 */    u8          ttl;        /* TTL for IPv4, HL for IPv6 */    __be32                  label;          /* Flow Label for IPv6 */    __be16          tp_src;    __be16          tp_dst;};

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Key parsing in the OvS