The C and C++ Include Header Files

/usr/include/netinet/ip6.h


$ cat -n /usr/include/netinet/ip6.h

     1	/* Copyright (C) 1991-2024 Free Software Foundation, Inc.
     2	   This file is part of the GNU C Library.
     3	
     4	   The GNU C Library is free software; you can redistribute it and/or
     5	   modify it under the terms of the GNU Lesser General Public
     6	   License as published by the Free Software Foundation; either
     7	   version 2.1 of the License, or (at your option) any later version.
     8	
     9	   The GNU C Library is distributed in the hope that it will be useful,
    10	   but WITHOUT ANY WARRANTY; without even the implied warranty of
    11	   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    12	   Lesser General Public License for more details.
    13	
    14	   You should have received a copy of the GNU Lesser General Public
    15	   License along with the GNU C Library; if not, see
    16	   <https://www.gnu.org/licenses/>.  */
    17	
    18	#ifndef _NETINET_IP6_H
    19	#define _NETINET_IP6_H 1
    20	
    21	#include <inttypes.h>
    22	#include <netinet/in.h>
    23	
    24	struct ip6_hdr
    25	  {
    26	    union
    27	      {
    28		struct ip6_hdrctl
    29		  {
    30		    uint32_t ip6_un1_flow;   /* 4 bits version, 8 bits TC,
    31						20 bits flow-ID */
    32		    uint16_t ip6_un1_plen;   /* payload length */
    33		    uint8_t  ip6_un1_nxt;    /* next header */
    34		    uint8_t  ip6_un1_hlim;   /* hop limit */
    35		  } ip6_un1;
    36		uint8_t ip6_un2_vfc;       /* 4 bits version, top 4 bits tclass */
    37	      } ip6_ctlun;
    38	    struct in6_addr ip6_src;      /* source address */
    39	    struct in6_addr ip6_dst;      /* destination address */
    40	  };
    41	
    42	#define ip6_vfc   ip6_ctlun.ip6_un2_vfc
    43	#define ip6_flow  ip6_ctlun.ip6_un1.ip6_un1_flow
    44	#define ip6_plen  ip6_ctlun.ip6_un1.ip6_un1_plen
    45	#define ip6_nxt   ip6_ctlun.ip6_un1.ip6_un1_nxt
    46	#define ip6_hlim  ip6_ctlun.ip6_un1.ip6_un1_hlim
    47	#define ip6_hops  ip6_ctlun.ip6_un1.ip6_un1_hlim
    48	
    49	/* Generic extension header.  */
    50	struct ip6_ext
    51	  {
    52	    uint8_t  ip6e_nxt;		/* next header.  */
    53	    uint8_t  ip6e_len;		/* length in units of 8 octets.  */
    54	  };
    55	
    56	/* Hop-by-Hop options header.  */
    57	struct ip6_hbh
    58	  {
    59	    uint8_t  ip6h_nxt;		/* next header.  */
    60	    uint8_t  ip6h_len;		/* length in units of 8 octets.  */
    61	    /* followed by options */
    62	  };
    63	
    64	/* Destination options header */
    65	struct ip6_dest
    66	  {
    67	    uint8_t  ip6d_nxt;		/* next header */
    68	    uint8_t  ip6d_len;		/* length in units of 8 octets */
    69	    /* followed by options */
    70	  };
    71	
    72	/* Routing header */
    73	struct ip6_rthdr
    74	  {
    75	    uint8_t  ip6r_nxt;		/* next header */
    76	    uint8_t  ip6r_len;		/* length in units of 8 octets */
    77	    uint8_t  ip6r_type;		/* routing type */
    78	    uint8_t  ip6r_segleft;	/* segments left */
    79	    /* followed by routing type specific data */
    80	  };
    81	
    82	/* Type 0 Routing header */
    83	struct ip6_rthdr0
    84	  {
    85	    uint8_t  ip6r0_nxt;		/* next header */
    86	    uint8_t  ip6r0_len;		/* length in units of 8 octets */
    87	    uint8_t  ip6r0_type;	/* always zero */
    88	    uint8_t  ip6r0_segleft;	/* segments left */
    89	    uint8_t  ip6r0_reserved;	/* reserved field */
    90	    uint8_t  ip6r0_slmap[3];	/* strict/loose bit map */
    91	    /* followed by up to 127 struct in6_addr */
    92	    struct in6_addr ip6r0_addr[0];
    93	  };
    94	
    95	/* Fragment header */
    96	struct ip6_frag
    97	  {
    98	    uint8_t   ip6f_nxt;		/* next header */
    99	    uint8_t   ip6f_reserved;	/* reserved field */
   100	    uint16_t  ip6f_offlg;	/* offset, reserved, and flag */
   101	    uint32_t  ip6f_ident;	/* identification */
   102	  };
   103	
   104	#if __BYTE_ORDER == __BIG_ENDIAN
   105	# define IP6F_OFF_MASK       0xfff8  /* mask out offset from _offlg */
   106	# define IP6F_RESERVED_MASK  0x0006  /* reserved bits in ip6f_offlg */
   107	# define IP6F_MORE_FRAG      0x0001  /* more-fragments flag */
   108	#else   /* __BYTE_ORDER == __LITTLE_ENDIAN */
   109	# define IP6F_OFF_MASK       0xf8ff  /* mask out offset from _offlg */
   110	# define IP6F_RESERVED_MASK  0x0600  /* reserved bits in ip6f_offlg */
   111	# define IP6F_MORE_FRAG      0x0100  /* more-fragments flag */
   112	#endif
   113	
   114	/* IPv6 options */
   115	struct ip6_opt
   116	  {
   117	    uint8_t  ip6o_type;
   118	    uint8_t  ip6o_len;
   119	  };
   120	
   121	/* The high-order 3 bits of the option type define the behavior
   122	 * when processing an unknown option and whether or not the option
   123	 * content changes in flight.
   124	 */
   125	#define IP6OPT_TYPE(o)		((o) & 0xc0)
   126	#define IP6OPT_TYPE_SKIP	0x00
   127	#define IP6OPT_TYPE_DISCARD	0x40
   128	#define IP6OPT_TYPE_FORCEICMP	0x80
   129	#define IP6OPT_TYPE_ICMP	0xc0
   130	#define IP6OPT_TYPE_MUTABLE	0x20
   131	
   132	/* Special option types for padding.  */
   133	#define IP6OPT_PAD1	0
   134	#define IP6OPT_PADN	1
   135	
   136	#define IP6OPT_JUMBO		0xc2
   137	#define IP6OPT_NSAP_ADDR	0xc3
   138	#define IP6OPT_TUNNEL_LIMIT	0x04
   139	#define IP6OPT_ROUTER_ALERT	0x05
   140	
   141	/* Jumbo Payload Option */
   142	struct ip6_opt_jumbo
   143	  {
   144	    uint8_t  ip6oj_type;
   145	    uint8_t  ip6oj_len;
   146	    uint8_t  ip6oj_jumbo_len[4];
   147	  };
   148	#define IP6OPT_JUMBO_LEN	6
   149	
   150	/* NSAP Address Option */
   151	struct ip6_opt_nsap
   152	  {
   153	    uint8_t  ip6on_type;
   154	    uint8_t  ip6on_len;
   155	    uint8_t  ip6on_src_nsap_len;
   156	    uint8_t  ip6on_dst_nsap_len;
   157	      /* followed by source NSAP */
   158	      /* followed by destination NSAP */
   159	  };
   160	
   161	/* Tunnel Limit Option */
   162	struct ip6_opt_tunnel
   163	  {
   164	    uint8_t  ip6ot_type;
   165	    uint8_t  ip6ot_len;
   166	    uint8_t  ip6ot_encap_limit;
   167	  };
   168	
   169	/* Router Alert Option */
   170	struct ip6_opt_router
   171	  {
   172	    uint8_t  ip6or_type;
   173	    uint8_t  ip6or_len;
   174	    uint8_t  ip6or_value[2];
   175	  };
   176	
   177	/* Router alert values (in network byte order) */
   178	#if __BYTE_ORDER == __BIG_ENDIAN
   179	# define IP6_ALERT_MLD	0x0000
   180	# define IP6_ALERT_RSVP	0x0001
   181	# define IP6_ALERT_AN	0x0002
   182	#else /* __BYTE_ORDER == __LITTLE_ENDIAN */
   183	# define IP6_ALERT_MLD	0x0000
   184	# define IP6_ALERT_RSVP	0x0100
   185	# define IP6_ALERT_AN	0x0200
   186	#endif
   187	
   188	#endif /* netinet/ip6.h */