inet6_rth_getaddr(3socket)

1inet6_rth(3SOCKET)         Sockets Library Functions        inet6_rth(3SOCKET)
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NAME

6       inet6_rth,      inet6_rth_space,     inet6_rth_init,     inet6_rth_add,
7       inet6_rth_reverse,  inet6_rth_segments,  inet6_rth_getaddr  -   Routing
8       header manipulation
9

SYNOPSIS

11       cc [ flag ... ] file ... -lsocket [library]
12       #include <netinet/in.h>
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14       socklen_t inet6_rth_space(int type, int segments);
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17       void *inet6_rth_init(void *bp, socklen_t bp_len, int type, int segments);
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20       int inet6_rth_add(void *bp, const struct, in6_addr *addr);
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23       int inet6_rth_reverse(const void *in, void *out);
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26       int inet6_rth_segments(const void *bp);
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29       struct in6_addr *inet6_rth_getaddr(const void *bp, int index);
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DESCRIPTION

33       The  inet6_rth  functions  enable  users  to manipulate routing headers
34       without having knowledge of their structure.
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36
37       The iet6_rth_init() function initializes the buffer pointed to by bp to
38       contain  a routing header of the specified type and sets ip6r_len based
39       on the segments parameter. The bp_len argument is used only  to  verify
40       that  the buffer is large enough. The ip6r_segleft field is set to zero
41       and inet6_rth_add() increments it. The caller allocates the buffer  and
42       its size can be determined by calling inet6_rth_space().
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44
45       The  inet6_rth_add()  function adds the IPv6 address pointed to by addr
46       to the end of the routing header that is being constructed.
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49       The inet6_rth_reverse()  function  takes  a  routing  header  extension
50       header pointed to by the first argument and writes a new routing header
51       that sends datagrams along the  reverse  of  the  route.  The  function
52       reverses  the order of the addresses and sets the segleft member in the
53       new routing header to the number of segments. Both arguments can  point
54       to the same buffer (that is, the reversal can occur in place).
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56
57       The  inet6_rth_segments()  function  returns  the  number  of  segments
58       (addresses) contained in the routing header described by bp.
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60
61       The inet6_rth_getaddr() function returns a pointer to the IPv6  address
62       specified by index, which must have a value between 0 and one less than
63       the value  returned  by  inet6_rth_segments()  in  the  routing  header
64       described by bp. Applications should first call inet6_rth_segments() to
65       obtain the number of segments in the routing header.
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68       The inet6_rth_space() function returns the size, but the function  does
69       not allocate the space required for the ancillary data routing header.
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ROUTING HEADERS

72       To   receive   a  routing  header,  the  application  must  enable  the
73       IPV6_RECVRTHDR socket option:
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75         int  on = 1;
76         setsockopt (fd, IPPROTO_IPV6, IPV6_RECVRTHDR, &on, sizeof(on));
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80       Each received routing header is returned as one ancillary  data  object
81       described by a cmsghdr structure with cmsg_type set to IPV6_RTHDR.
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84       To send a routing header, the application specifies it either as ancil‐
85       lary data in a call to sendmsg() or  by  using  setsockopt().  For  the
86       sending side, this API assumes the number of occurrences of the routing
87       header as described in RFC-2460. Applications can specify no more  than
88       one outgoing routing header.
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91       The  application  can  remove any sticky routing header by calling set‐
92       sockopt() for IPV6_RTHDR with a zero option length.
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95       When using ancillary data, a  routing  header  is  passed  between  the
96       application  and  the  kernel  as  follows: The cmsg_level member has a
97       value  of  IPPROTO_IPV6  and  the  cmsg_type  member  has  a  value  of
98       IPV6_RTHDR.  The  contents  of  the cmsg_data member is implementation-
99       dependent and should not be accessed directly by the  application,  but
100       should be accessed using the inet6_rth functions.
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102
103       The  following  constant  is  defined  as  a  result  of  including the
104       <netinet/in.h>:
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106         #define IPV6_RTHDR_TYPE_0   0 /* IPv6 Routing header type 0 */
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108
109   ROUTING HEADER OPTION
110       Source routing in IPv6 is accomplished by specifying a  routing  header
111       as  an  extension header. There are a number of different routing head‐
112       ers, but IPv6 currently defines only the Type 0 header.  See  RFC-2460.
113       The Type 0 header supports up to 127 intermediate nodes, limited by the
114       length field in the extension  header.  With  this  maximum  number  of
115       intermediate nodes, a source, and a destination, there are 128 hops.
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RETURN VALUES

118       The inet6_rth_init() function returns a pointer to the buffer (bp) upon
119       success.
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121
122       For the inet6_rth_add() function, the segleft  member  of  the  routing
123       header is updated to account for the new address in the routing header.
124       The function returns 0 upon success and -1 upon failure.
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126
127       The inet6_rth_reverse() function returns 0 upon success or -1  upon  an
128       error.
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131       The inet6_rth_segments() function returns 0 or greater upon success and
132       -1 upon an error.
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134
135       The inet6_rth_getaddr() function returns NULL upon an error.
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137
138       The inet6_rth_space() function returns the size of  the  buffer  needed
139       for the routing header.
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ATTRIBUTES

142       See attributes(5) for descriptions of the following attributes:
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147       ┌─────────────────────────────┬─────────────────────────────┐
148       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
149       ├─────────────────────────────┼─────────────────────────────┤
150       │Interface Stability          │Standard                     │
151       ├─────────────────────────────┼─────────────────────────────┤
152       │MT-Level                     │Safe                         │
153       └─────────────────────────────┴─────────────────────────────┘
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NAME

SYNOPSIS

DESCRIPTION

ROUTING HEADERS

RETURN VALUES

ATTRIBUTES

SEE ALSO