text: /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
  #ifndef _NF_CONNTRACK_COMMON_H
  #define _NF_CONNTRACK_COMMON_H
  /* Connection state tracking for netfilter.  This is separated from,
     but required by, the NAT layer; it can also be used by an iptables
     extension. */
  enum ip_conntrack_info {
  	/* Part of an established connection (either direction). */
  	IP_CT_ESTABLISHED,
  
  	/* Like NEW, but related to an existing connection, or ICMP error
  	   (in either direction). */
  	IP_CT_RELATED,
  
  	/* Started a new connection to track (only
             IP_CT_DIR_ORIGINAL); may be a retransmission. */
  	IP_CT_NEW,
  
  	/* >= this indicates reply direction */
  	IP_CT_IS_REPLY,
  
  	IP_CT_ESTABLISHED_REPLY = IP_CT_ESTABLISHED + IP_CT_IS_REPLY,
  	IP_CT_RELATED_REPLY = IP_CT_RELATED + IP_CT_IS_REPLY,
  	/* No NEW in reply direction. */
  
  	/* Number of distinct IP_CT types. */
  	IP_CT_NUMBER,
  
  	/* only for userspace compatibility */
  	IP_CT_NEW_REPLY = IP_CT_NUMBER,
  };
  
  #define NF_CT_STATE_INVALID_BIT			(1 << 0)
  #define NF_CT_STATE_BIT(ctinfo)			(1 << ((ctinfo) % IP_CT_IS_REPLY + 1))
  #define NF_CT_STATE_UNTRACKED_BIT		(1 << 6)
  
  /* Bitset representing status of connection. */
  enum ip_conntrack_status {
  	/* It's an expected connection: bit 0 set.  This bit never changed */
  	IPS_EXPECTED_BIT = 0,
  	IPS_EXPECTED = (1 << IPS_EXPECTED_BIT),
  
  	/* We've seen packets both ways: bit 1 set.  Can be set, not unset. */
  	IPS_SEEN_REPLY_BIT = 1,
  	IPS_SEEN_REPLY = (1 << IPS_SEEN_REPLY_BIT),
  
  	/* Conntrack should never be early-expired. */
  	IPS_ASSURED_BIT = 2,
  	IPS_ASSURED = (1 << IPS_ASSURED_BIT),
  
  	/* Connection is confirmed: originating packet has left box */
  	IPS_CONFIRMED_BIT = 3,
  	IPS_CONFIRMED = (1 << IPS_CONFIRMED_BIT),
  
  	/* Connection needs src nat in orig dir.  This bit never changed. */
  	IPS_SRC_NAT_BIT = 4,
  	IPS_SRC_NAT = (1 << IPS_SRC_NAT_BIT),
  
  	/* Connection needs dst nat in orig dir.  This bit never changed. */
  	IPS_DST_NAT_BIT = 5,
  	IPS_DST_NAT = (1 << IPS_DST_NAT_BIT),
  
  	/* Both together. */
  	IPS_NAT_MASK = (IPS_DST_NAT | IPS_SRC_NAT),
  
  	/* Connection needs TCP sequence adjusted. */
  	IPS_SEQ_ADJUST_BIT = 6,
  	IPS_SEQ_ADJUST = (1 << IPS_SEQ_ADJUST_BIT),
  
  	/* NAT initialization bits. */
  	IPS_SRC_NAT_DONE_BIT = 7,
  	IPS_SRC_NAT_DONE = (1 << IPS_SRC_NAT_DONE_BIT),
  
  	IPS_DST_NAT_DONE_BIT = 8,
  	IPS_DST_NAT_DONE = (1 << IPS_DST_NAT_DONE_BIT),
  
  	/* Both together */
  	IPS_NAT_DONE_MASK = (IPS_DST_NAT_DONE | IPS_SRC_NAT_DONE),
  
  	/* Connection is dying (removed from lists), can not be unset. */
  	IPS_DYING_BIT = 9,
  	IPS_DYING = (1 << IPS_DYING_BIT),
  
  	/* Connection has fixed timeout. */
  	IPS_FIXED_TIMEOUT_BIT = 10,
  	IPS_FIXED_TIMEOUT = (1 << IPS_FIXED_TIMEOUT_BIT),
  
  	/* Conntrack is a template */
  	IPS_TEMPLATE_BIT = 11,
  	IPS_TEMPLATE = (1 << IPS_TEMPLATE_BIT),
  
  	/* Conntrack is a fake untracked entry.  Obsolete and not used anymore */
  	IPS_UNTRACKED_BIT = 12,
  	IPS_UNTRACKED = (1 << IPS_UNTRACKED_BIT),
  
  
  	/* Conntrack got a helper explicitly attached via CT target. */
  	IPS_HELPER_BIT = 13,
  	IPS_HELPER = (1 << IPS_HELPER_BIT),
  
  	/* Conntrack has been offloaded to flow table. */
  	IPS_OFFLOAD_BIT = 14,
  	IPS_OFFLOAD = (1 << IPS_OFFLOAD_BIT),
  
  	/* Be careful here, modifying these bits can make things messy,
  	 * so don't let users modify them directly.
  	 */
  	IPS_UNCHANGEABLE_MASK = (IPS_NAT_DONE_MASK | IPS_NAT_MASK |
  				 IPS_EXPECTED | IPS_CONFIRMED | IPS_DYING |
  				 IPS_SEQ_ADJUST | IPS_TEMPLATE | IPS_UNTRACKED |
  				 IPS_OFFLOAD),
  
  	__IPS_MAX_BIT = 15,
  };
  
  /* Connection tracking event types */
  enum ip_conntrack_events {
  	IPCT_NEW,		/* new conntrack */
  	IPCT_RELATED,		/* related conntrack */
  	IPCT_DESTROY,		/* destroyed conntrack */
  	IPCT_REPLY,		/* connection has seen two-way traffic */
  	IPCT_ASSURED,		/* connection status has changed to assured */
  	IPCT_PROTOINFO,		/* protocol information has changed */
  	IPCT_HELPER,		/* new helper has been set */
  	IPCT_MARK,		/* new mark has been set */
  	IPCT_SEQADJ,		/* sequence adjustment has changed */
  	IPCT_NATSEQADJ = IPCT_SEQADJ,
  	IPCT_SECMARK,		/* new security mark has been set */
  	IPCT_LABEL,		/* new connlabel has been set */
  	IPCT_SYNPROXY,		/* synproxy has been set */
  };
  
  enum ip_conntrack_expect_events {
  	IPEXP_NEW,		/* new expectation */
  	IPEXP_DESTROY,		/* destroyed expectation */
  };
  
  /* expectation flags */
  #define NF_CT_EXPECT_PERMANENT		0x1
  #define NF_CT_EXPECT_INACTIVE		0x2
  #define NF_CT_EXPECT_USERSPACE		0x4
  
  
  #endif /* _NF_CONNTRACK_COMMON_H */
  