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1 .\" $NetBSD: inet6_rth_space.3,v 1.2 2014/01/04 15:37:46 wiz Exp $
2 .\" $KAME: inet6_rth_space.3,v 1.7 2005/01/05 03:00:44 itojun Exp $
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31 .Dd December 24, 2004
32 .Dt INET6_RTH_SPACE 3
33 .Os
34 .\"
35 .Sh NAME
36 .Nm inet6_rth_space ,
37 .Nm inet6_rth_init ,
38 .Nm inet6_rth_add ,
39 .Nm inet6_rth_reverse ,
40 .Nm inet6_rth_segments ,
41 .Nm inet6_rth_getaddr
42 .Nd IPv6 Routing Header Options manipulation
43 .\"
44 .Sh SYNOPSIS
45 .In netinet/in.h
46 .Ft socklen_t
47 .Fn inet6_rth_space "int" "int"
48 .Ft "void *"
49 .Fn inet6_rth_init "void *" "socklen_t" "int" "int"
50 .Ft int
51 .Fn inet6_rth_add "void *" "const struct in6_addr *"
52 .Ft int
53 .Fn inet6_rth_reverse "const void *" "void *"
54 .Ft int
55 .Fn inet6_rth_segments "const void *"
56 .Ft "struct in6_addr *"
57 .Fn inet6_rth_getaddr "const void *" "int"
58 .\"
59 .Sh DESCRIPTION
60 The IPv6 Advanced API, RFC 3542, defines the functions that an
61 application calls to build and examine IPv6 Routing headers.
62 Routing headers are used to perform source routing in IPv6 networks.
63 The RFC uses the word
64 .Dq segments
65 to describe addresses and that is the term used here as well.
66 All of the functions are defined in the
67 .In netinet/in.h
68 header file.
69 The functions described in this manual page all operate
70 on routing header structures which are defined in
71 .In netinet/ip6.h
72 but which should not need to be modified outside the use of this API.
73 The size and shape of the route header structures may change, so using
74 the APIs is a more portable, long term, solution.
75 .Pp
76 The functions in the API are split into two groups, those that build a
77 routing header and those that parse a received routing header.
78 We will describe the builder functions followed by the parser functions.
79 .Ss inet6_rth_space
80 The
81 .Fn inet6_rth_space
82 function returns the number of bytes required to hold a Routing Header
83 of the type, specified in the
84 .Fa type
85 argument and containing the number of addresses specified in the
86 .Fa segments
87 argumment.
88 When the type is
89 .Dv IPV6_RTHDR_TYPE_0
90 the number of segments must be from 0 through 127.
91 Routing headers of type
92 .Dv IPV6_RTHDR_TYPE_2
93 contain only one segment, and are only used with Mobile IPv6.
94 The return value from this function is the number of bytes required to
95 store the routing header.
96 If the value 0 is returned then either the
97 route header type was not recognized or another error occurred.
98 .Ss inet6_rth_init
99 The
100 .Fn inet6_rth_init
101 function initializes the pre-allocated buffer pointed to by
102 .Fa bp
103 to contain a routing header of the specified type The
104 .Fa bp_len
105 argument is used to verify that the buffer is large enough.
106 The caller must allocate the buffer pointed to by bp.
107 The necessary buffer size should be determined by calling
108 .Fn inet6_rth_space
109 described in the previous sections.
110 .Pp
111 The
112 .Fn inet6_rth_init
113 function returns a pointer to
114 .Fa bp
115 on success and
116 .Dv NULL
117 when there is an error.
118 .Ss inet6_rth_add
119 The
120 .Fn inet6_rth_add
121 function adds the IPv6 address pointed to by
122 .Fa addr
123 to the end of the routing header being constructed.
124 .Pp
125 A successful addition results in the function returning 0, otherwise
126 \-1 is returned.
127 .Ss inet6_rth_reverse
128 The
129 .Fn inet6_rth_reverse
130 function takes a routing header, pointed to by the
131 argument
132 .Fa in ,
133 and writes a new routing header into the argument pointed to by
134 .Fa out .
135 The routing header at that sends datagrams along the reverse of that
136 route.
137 Both arguments are allowed to point to the same buffer meaning
138 that the reversal can occur in place.
139 .Pp
140 The return value of the function is 0 on success, or \-1 when
141 there is an error.
142 .\"
143 .Pp
144 The next set of functions operate on a routing header that the
145 application wants to parse.
146 In the usual case such a routing header
147 is received from the network, although these functions can also be
148 used with routing headers that the application itself created.
149 .Ss inet6_rth_segments
150 The
151 .Fn inet6_rth_segments
152 function returns the number of segments contained in the
153 routing header pointed to by
154 .Fa bp .
155 The return value is the number of segments contained in the routing
156 header, or \-1 if an error occurred.
157 It is not an error for 0 to be
158 returned as a routing header may contain 0 segments.
159 .\"
160 .Ss inet6_rth_getaddr
161 The
162 .Fn inet6_rth_getaddr
163 function is used to retrieve a single address from a routing header.
164 The
165 .Fa index
166 is the location in the routing header from which the application wants
167 to retrieve an address.
168 The
169 .Fa index
170 parameter must have a value between 0 and one less than the number of
171 segments present in the routing header.
172 The
173 .Fn inet6_rth_segments
174 function, described in the last section, should be used to determine
175 the total number of segments in the routing header.
176 The
177 .Fn inet6_rth_getaddr
178 function returns a pointer to an IPv6 address on success or
179 .Dv NULL
180 when an error has occurred.
181 .\"
182 .Sh EXAMPLES
183 RFC 3542 gives extensive examples in Section 21, Appendix B.
184 .Pp
185 KAME also provides examples in the advapitest directory of its kit.
186 .\"
187 .Sh DIAGNOSTICS
188 The
189 .Fn inet6_rth_space
190 and
191 .Fn inet6_rth_getaddr
192 functions return 0 on errors.
193 .Pp
194 The
195 .Fn inet6_rthdr_init
196 function returns
197 .Dv NULL
198 on error.
199 The
200 .Fn inet6_rth_add
201 and
202 .Fn inet6_rth_reverse
203 functions return 0 on success, or \-1 upon an error.
204 .\"
205 .Sh SEE ALSO
206 .Rs
207 .%A W. Stevens
208 .%A M. Thomas
209 .%A E. Nordmark
210 .%A T. Jinmei
211 .%T "Advanced Sockets API for IPv6"
212 .%N RFC 3542
213 .%D May 2003
214 .Re
215 .Rs
216 .%A S. Deering
217 .%A R. Hinden
218 .%T "Internet Protocol, Version 6 (IPv6) Specification"
219 .%N RFC2460
220 .%D December 1998
221 .Re
222 .Sh HISTORY
223 The implementation first appeared in KAME advanced networking kit.