rfc2292.txt

netcat

   /* Hop-by-Hop options header */
   /* XXX should we pad it to force alignment on an 8-byte boundary? */
   struct ip6_hbh {
     uint8_t  ip6h_nxt;        /* next header */
     uint8_t  ip6h_len;        /* length in units of 8 octets */
       /* followed by options */
   };

   /* Destination options header */
   /* XXX should we pad it to force alignment on an 8-byte boundary? */
   struct ip6_dest {
     uint8_t  ip6d_nxt;        /* next header */
     uint8_t  ip6d_len;        /* length in units of 8 octets */
       /* followed by options */
   };

   /* Routing header */
   struct ip6_rthdr {



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     uint8_t  ip6r_nxt;        /* next header */
     uint8_t  ip6r_len;        /* length in units of 8 octets */
     uint8_t  ip6r_type;       /* routing type */
     uint8_t  ip6r_segleft;    /* segments left */
       /* followed by routing type specific data */
   };

   /* Type 0 Routing header */
   struct ip6_rthdr0 {
     uint8_t  ip6r0_nxt;       /* next header */
     uint8_t  ip6r0_len;       /* length in units of 8 octets */
     uint8_t  ip6r0_type;      /* always zero */
     uint8_t  ip6r0_segleft;   /* segments left */
     uint8_t  ip6r0_reserved;  /* reserved field */
     uint8_t  ip6r0_slmap[3];  /* strict/loose bit map */
     struct in6_addr  ip6r0_addr[1];  /* up to 23 addresses */
   };

   /* Fragment header */
   struct ip6_frag {
     uint8_t   ip6f_nxt;       /* next header */
     uint8_t   ip6f_reserved;  /* reserved field */
     uint16_t  ip6f_offlg;     /* offset, reserved, and flag */
     uint32_t  ip6f_ident;     /* identification */
   };

   #if     BYTE_ORDER == BIG_ENDIAN
   #define IP6F_OFF_MASK       0xfff8  /* mask out offset from _offlg */
   #define IP6F_RESERVED_MASK  0x0006  /* reserved bits in ip6f_offlg */
   #define IP6F_MORE_FRAG      0x0001  /* more-fragments flag */
   #else   /* BYTE_ORDER == LITTLE_ENDIAN */
   #define IP6F_OFF_MASK       0xf8ff  /* mask out offset from _offlg */
   #define IP6F_RESERVED_MASK  0x0600  /* reserved bits in ip6f_offlg */
   #define IP6F_MORE_FRAG      0x0100  /* more-fragments flag */
   #endif

   Defined constants for fields larger than 1 byte depend on the byte
   ordering that is used.  This API assumes that the fields in the
   protocol headers are left in the network byte order, which is big-
   endian for the Internet protocols.  If not, then either these
   constants or the fields being tested must be converted at run-time,
   using something like htons() or htonl().

   (Note: We show an implementation that supports both big-endian and
   little-endian byte ordering, assuming a hypothetical compile-time #if
   test to determine the byte ordering.  The constant that we show,





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   BYTE_ORDER, with values of BIG_ENDIAN and LITTLE_ENDIAN, are for
   example purposes only.  If an implementation runs on only one type of
   hardware it need only define the set of constants for that hardware's
   byte ordering.)

2.2.  The icmp6_hdr Structure

   The ICMPv6 header is needed by numerous IPv6 applications including
   Ping, Traceroute, router discovery daemons, and neighbor discovery
   daemons.  The following structure is defined as a result of including
   <netinet/icmp6.h>.  Note that this is a new header.

   struct icmp6_hdr {
     uint8_t     icmp6_type;   /* type field */
     uint8_t     icmp6_code;   /* code field */
     uint16_t    icmp6_cksum;  /* checksum field */
     union {
       uint32_t  icmp6_un_data32[1]; /* type-specific field */
       uint16_t  icmp6_un_data16[2]; /* type-specific field */
       uint8_t   icmp6_un_data8[4];  /* type-specific field */
     } icmp6_dataun;
   };

   #define icmp6_data32    icmp6_dataun.icmp6_un_data32
   #define icmp6_data16    icmp6_dataun.icmp6_un_data16
   #define icmp6_data8     icmp6_dataun.icmp6_un_data8
   #define icmp6_pptr      icmp6_data32[0]  /* parameter prob */
   #define icmp6_mtu       icmp6_data32[0]  /* packet too big */
   #define icmp6_id        icmp6_data16[0]  /* echo request/reply */
   #define icmp6_seq       icmp6_data16[1]  /* echo request/reply */
   #define icmp6_maxdelay  icmp6_data16[0]  /* mcast group membership */

2.2.1.  ICMPv6 Type and Code Values

   In addition to a common structure for the ICMPv6 header, common
   definitions are required for the ICMPv6 type and code fields.  The
   following constants are also defined as a result of including
   <netinet/icmp6.h>.

#define ICMP6_DST_UNREACH             1
#define ICMP6_PACKET_TOO_BIG          2
#define ICMP6_TIME_EXCEEDED           3
#define ICMP6_PARAM_PROB              4

#define ICMP6_INFOMSG_MASK  0x80    /* all informational messages */

#define ICMP6_ECHO_REQUEST          128
#define ICMP6_ECHO_REPLY            129



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#define ICMP6_MEMBERSHIP_QUERY      130
#define ICMP6_MEMBERSHIP_REPORT     131
#define ICMP6_MEMBERSHIP_REDUCTION  132

#define ICMP6_DST_UNREACH_NOROUTE     0 /* no route to destination */
#define ICMP6_DST_UNREACH_ADMIN       1 /* communication with */
                                        /* destination */
                                        /* administratively */
                                        /* prohibited */
#define ICMP6_DST_UNREACH_NOTNEIGHBOR 2 /* not a neighbor */
#define ICMP6_DST_UNREACH_ADDR        3 /* address unreachable */
#define ICMP6_DST_UNREACH_NOPORT      4 /* bad port */

#define ICMP6_TIME_EXCEED_TRANSIT     0 /* Hop Limit == 0 in transit */
#define ICMP6_TIME_EXCEED_REASSEMBLY  1 /* Reassembly time out */

#define ICMP6_PARAMPROB_HEADER        0 /* erroneous header field */
#define ICMP6_PARAMPROB_NEXTHEADER    1 /* unrecognized Next Header */
#define ICMP6_PARAMPROB_OPTION        2 /* unrecognized IPv6 option */

   The five ICMP message types defined by IPv6 neighbor discovery (133-
   137) are defined in the next section.

2.2.2.  ICMPv6 Neighbor Discovery Type and Code Values

   The following structures and definitions are defined as a result of
   including <netinet/icmp6.h>.

   #define ND_ROUTER_SOLICIT           133
   #define ND_ROUTER_ADVERT            134
   #define ND_NEIGHBOR_SOLICIT         135
   #define ND_NEIGHBOR_ADVERT          136
   #define ND_REDIRECT                 137

   struct nd_router_solicit {     /* router solicitation */
     struct icmp6_hdr  nd_rs_hdr;
       /* could be followed by options */
   };

   #define nd_rs_type               nd_rs_hdr.icmp6_type
   #define nd_rs_code               nd_rs_hdr.icmp6_code
   #define nd_rs_cksum              nd_rs_hdr.icmp6_cksum
   #define nd_rs_reserved           nd_rs_hdr.icmp6_data32[0]

   struct nd_router_advert {      /* router advertisement */
     struct icmp6_hdr  nd_ra_hdr;
     uint32_t   nd_ra_reachable;   /* reachable time */
     uint32_t   nd_ra_retransmit;  /* retransmit timer */



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       /* could be followed by options */
   };

   #define nd_ra_type               nd_ra_hdr.icmp6_type
   #define nd_ra_code               nd_ra_hdr.icmp6_code
   #define nd_ra_cksum              nd_ra_hdr.icmp6_cksum
   #define nd_ra_curhoplimit        nd_ra_hdr.icmp6_data8[0]
   #define nd_ra_flags_reserved     nd_ra_hdr.icmp6_data8[1]
   #define ND_RA_FLAG_MANAGED       0x80
   #define ND_RA_FLAG_OTHER         0x40
   #define nd_ra_router_lifetime    nd_ra_hdr.icmp6_data16[1]

   struct nd_neighbor_solicit {   /* neighbor solicitation */
     struct icmp6_hdr  nd_ns_hdr;
     struct in6_addr   nd_ns_target; /* target address */
       /* could be followed by options */
   };

   #define nd_ns_type               nd_ns_hdr.icmp6_type
   #define nd_ns_code               nd_ns_hdr.icmp6_code
   #define nd_ns_cksum              nd_ns_hdr.icmp6_cksum
   #define nd_ns_reserved           nd_ns_hdr.icmp6_data32[0]

   struct nd_neighbor_advert {    /* neighbor advertisement */
     struct icmp6_hdr  nd_na_hdr;
     struct in6_addr   nd_na_target; /* target address */
       /* could be followed by options */
   };

   #define nd_na_type               nd_na_hdr.icmp6_type
   #define nd_na_code               nd_na_hdr.icmp6_code
   #define nd_na_cksum              nd_na_hdr.icmp6_cksum
   #define nd_na_flags_reserved     nd_na_hdr.icmp6_data32[0]
   #if     BYTE_ORDER == BIG_ENDIAN
   #define ND_NA_FLAG_ROUTER        0x80000000
   #define ND_NA_FLAG_SOLICITED     0x40000000
   #define ND_NA_FLAG_OVERRIDE      0x20000000
   #else   /* BYTE_ORDER == LITTLE_ENDIAN */
   #define ND_NA_FLAG_ROUTER        0x00000080
   #define ND_NA_FLAG_SOLICITED     0x00000040
   #define ND_NA_FLAG_OVERRIDE      0x00000020
   #endif

   struct nd_redirect {           /* redirect */
     struct icmp6_hdr  nd_rd_hdr;
     struct in6_addr   nd_rd_target; /* target address */
     struct in6_addr   nd_rd_dst;    /* destination address */
       /* could be followed by options */



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   };

   #define nd_rd_type               nd_rd_hdr.icmp6_type
   #define nd_rd_code               nd_rd_hdr.icmp6_code
   #define nd_rd_cksum              nd_rd_hdr.icmp6_cksum
   #define nd_rd_reserved           nd_rd_hdr.icmp6_data32[0]

   struct nd_opt_hdr {           /* Neighbor discovery option header */
     uint8_t  nd_opt_type;
     uint8_t  nd_opt_len;        /* in units of 8 octets */
       /* followed by option specific data */
   };

   #define  ND_OPT_SOURCE_LINKADDR       1
   #define  ND_OPT_TARGET_LINKADDR       2
   #define  ND_OPT_PREFIX_INFORMATION    3
   #define  ND_OPT_REDIRECTED_HEADER     4
   #define  ND_OPT_MTU                   5

   struct nd_opt_prefix_info {    /* prefix information */
     uint8_t   nd_opt_pi_type;
     uint8_t   nd_opt_pi_len;
     uint8_t   nd_opt_pi_prefix_len;
     uint8_t   nd_opt_pi_flags_reserved;
     uint32_t  nd_opt_pi_valid_time;
     uint32_t  nd_opt_pi_preferred_time;
     uint32_t  nd_opt_pi_reserved2;
     struct in6_addr  nd_opt_pi_prefix;
   };

   #define ND_OPT_PI_FLAG_ONLINK        0x80
   #define ND_OPT_PI_FLAG_AUTO          0x40

   struct nd_opt_rd_hdr {         /* redirected header */
     uint8_t   nd_opt_rh_type;
     uint8_t   nd_opt_rh_len;
     uint16_t  nd_opt_rh_reserved1;
     uint32_t  nd_opt_rh_reserved2;
       /* followed by IP header and data */
   };

   struct nd_opt_mtu {            /* MTU option */
     uint8_t   nd_opt_mtu_type;
     uint8_t   nd_opt_mtu_len;
     uint16_t  nd_opt_mtu_reserved;
     uint32_t  nd_opt_mtu_mtu;
   };




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   We note that the nd_na_flags_reserved flags have the same byte
   ordering problems as we discussed with ip6f_offlg.

2.3.  Address Testing Macros

   The basic API ([RFC-2133]) defines some macros for testing an IPv6
   address for certain properties.  This API extends those definitions
   with additional address testing macros, defined as a result of
   including <netinet/in.h>.