1. 根目录:
2. include
3. net
4. flow_dissector.h

#ifndef _NET_FLOW_DISSECTOR_H
#define _NET_FLOW_DISSECTOR_H

#include <linux/types.h>
#include <linux/in6.h>
#include <uapi/linux/if_ether.h>

/**
 * struct flow_dissector_key_control:
 * @thoff: Transport header offset
 */
struct flow_dissector_key_control {
	u16	thoff;
	u16	addr_type;
	u32	flags;
};

#define FLOW_DIS_IS_FRAGMENT	BIT(0)
#define FLOW_DIS_FIRST_FRAG	BIT(1)
#define FLOW_DIS_ENCAPSULATION	BIT(2)

/**
 * struct flow_dissector_key_basic:
 * @thoff: Transport header offset
 * @n_proto: Network header protocol (eg. IPv4/IPv6)
 * @ip_proto: Transport header protocol (eg. TCP/UDP)
 */
struct flow_dissector_key_basic {
	__be16	n_proto;
	u8	ip_proto;
	u8	padding;
};

struct flow_dissector_key_tags {
	u32	vlan_id:12,
		flow_label:20;
};

struct flow_dissector_key_keyid {
	__be32	keyid;
};

/**
 * struct flow_dissector_key_ipv4_addrs:
 * @src: source ip address
 * @dst: destination ip address
 */
struct flow_dissector_key_ipv4_addrs {
	/* (src,dst) must be grouped, in the same way than in IP header */
	__be32 src;
	__be32 dst;
};

/**
 * struct flow_dissector_key_ipv6_addrs:
 * @src: source ip address
 * @dst: destination ip address
 */
struct flow_dissector_key_ipv6_addrs {
	/* (src,dst) must be grouped, in the same way than in IP header */
	struct in6_addr src;
	struct in6_addr dst;
};

/**
 * struct flow_dissector_key_tipc_addrs:
 * @srcnode: source node address
 */
struct flow_dissector_key_tipc_addrs {
	__be32 srcnode;
};

/**
 * struct flow_dissector_key_addrs:
 * @v4addrs: IPv4 addresses
 * @v6addrs: IPv6 addresses
 */
struct flow_dissector_key_addrs {
	union {
		struct flow_dissector_key_ipv4_addrs v4addrs;
		struct flow_dissector_key_ipv6_addrs v6addrs;
		struct flow_dissector_key_tipc_addrs tipcaddrs;
	};
};

/**
 * flow_dissector_key_tp_ports:
 *	@ports: port numbers of Transport header
 *		src: source port number
 *		dst: destination port number
 */
struct flow_dissector_key_ports {
	union {
		__be32 ports;
		struct {
			__be16 src;
			__be16 dst;
		};
	};
};


/**
 * struct flow_dissector_key_eth_addrs:
 * @src: source Ethernet address
 * @dst: destination Ethernet address
 */
struct flow_dissector_key_eth_addrs {
	/* (dst,src) must be grouped, in the same way than in ETH header */
	unsigned char dst[ETH_ALEN];
	unsigned char src[ETH_ALEN];
};

enum flow_dissector_key_id {
	FLOW_DISSECTOR_KEY_CONTROL, /* struct flow_dissector_key_control */
	FLOW_DISSECTOR_KEY_BASIC, /* struct flow_dissector_key_basic */
	FLOW_DISSECTOR_KEY_IPV4_ADDRS, /* struct flow_dissector_key_ipv4_addrs */
	FLOW_DISSECTOR_KEY_IPV6_ADDRS, /* struct flow_dissector_key_ipv6_addrs */
	FLOW_DISSECTOR_KEY_PORTS, /* struct flow_dissector_key_ports */
	FLOW_DISSECTOR_KEY_ETH_ADDRS, /* struct flow_dissector_key_eth_addrs */
	FLOW_DISSECTOR_KEY_TIPC_ADDRS, /* struct flow_dissector_key_tipc_addrs */
	FLOW_DISSECTOR_KEY_VLANID, /* struct flow_dissector_key_flow_tags */
	FLOW_DISSECTOR_KEY_FLOW_LABEL, /* struct flow_dissector_key_flow_tags */
	FLOW_DISSECTOR_KEY_GRE_KEYID, /* struct flow_dissector_key_keyid */
	FLOW_DISSECTOR_KEY_MPLS_ENTROPY, /* struct flow_dissector_key_keyid */

	FLOW_DISSECTOR_KEY_MAX,
};

#define FLOW_DISSECTOR_F_PARSE_1ST_FRAG		BIT(0)
#define FLOW_DISSECTOR_F_STOP_AT_L3		BIT(1)
#define FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL	BIT(2)
#define FLOW_DISSECTOR_F_STOP_AT_ENCAP		BIT(3)

struct flow_dissector_key {
	enum flow_dissector_key_id key_id;
	size_t offset; /* offset of struct flow_dissector_key_*
			  in target the struct */
};

struct flow_dissector {
	unsigned int used_keys; /* each bit repesents presence of one key id */
	unsigned short int offset[FLOW_DISSECTOR_KEY_MAX];
};

struct flow_keys {
	struct flow_dissector_key_control control;
#define FLOW_KEYS_HASH_START_FIELD basic
	struct flow_dissector_key_basic basic;
	struct flow_dissector_key_tags tags;
	struct flow_dissector_key_keyid keyid;
	struct flow_dissector_key_ports ports;
	struct flow_dissector_key_addrs addrs;
};

#define FLOW_KEYS_HASH_OFFSET		\
	offsetof(struct flow_keys, FLOW_KEYS_HASH_START_FIELD)

__be32 flow_get_u32_src(const struct flow_keys *flow);
__be32 flow_get_u32_dst(const struct flow_keys *flow);

extern struct flow_dissector flow_keys_dissector;
extern struct flow_dissector flow_keys_buf_dissector;

/* struct flow_keys_digest:
 *
 * This structure is used to hold a digest of the full flow keys. This is a
 * larger "hash" of a flow to allow definitively matching specific flows where
 * the 32 bit skb->hash is not large enough. The size is limited to 16 bytes so
 * that it can by used in CB of skb (see sch_choke for an example).
 */
#define FLOW_KEYS_DIGEST_LEN	16
struct flow_keys_digest {
	u8	data[FLOW_KEYS_DIGEST_LEN];
};

void make_flow_keys_digest(struct flow_keys_digest *digest,
			   const struct flow_keys *flow);

static inline bool flow_keys_have_l4(struct flow_keys *keys)
{
	return (keys->ports.ports || keys->tags.flow_label);
}

u32 flow_hash_from_keys(struct flow_keys *keys);

#endif