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1 .\" $KAME: inet6_rth_space.3,v 1.7 2005/01/05 03:00:44 itojun Exp $
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30 .\" $FreeBSD: src/lib/libc/net/inet6_rth_space.3,v 1.10 2005/07/31 03:30:44 keramida Exp $
31 .\" $DragonFly: src/lib/libc/net/inet6_rth_space.3,v 1.2 2008/09/05 20:43:08 swildner Exp $
32 .\"
33 .Dd September 4, 2008
34 .Dt INET6_RTH_SPACE 3
35 .Os
36 .\"
37 .Sh NAME
38 .Nm inet6_rth_space ,
39 .Nm inet6_rth_init ,
40 .Nm inet6_rth_add ,
41 .Nm inet6_rth_reverse ,
42 .Nm inet6_rth_segments ,
43 .Nm inet6_rth_getaddr
44 .Nd IPv6 Routing Header Options manipulation
45 .\"
46 .Sh LIBRARY
47 .Lb libc
48 .Sh SYNOPSIS
49 .In netinet/in.h
50 .Ft socklen_t
51 .Fn inet6_rth_space "int type" "int segments"
52 .Ft "void *"
53 .Fn inet6_rth_init "void *bp" "socklen_t bp_len" "int type" "int segments"
54 .Ft int
55 .Fn inet6_rth_add "void *bp" "const struct in6_addr *addr"
56 .Ft int
57 .Fn inet6_rth_reverse "const void *in" "void *out"
58 .Ft int
59 .Fn inet6_rth_segments "const void *bp"
60 .Ft "struct in6_addr *"
61 .Fn inet6_rth_getaddr "const void *bp" "int idx"
62 .\"
63 .Sh DESCRIPTION
64 The IPv6 Advanced API, RFC 3542, defines the functions that an
65 application calls to build and examine IPv6 Routing headers.
66 Routing headers are used to perform source routing in IPv6 networks.
67 The RFC uses the word
68 .Dq segments
69 to describe addresses and that is the term used here as well.
70 All of the functions are defined in the
71 .In netinet/in.h
72 header file.
73 The functions described in this manual page all operate
74 on routing header structures which are defined in
75 .In netinet/ip6.h
76 but which should not need to be modified outside the use of this API.
77 The size and shape of the route header structures may change, so using
78 the APIs is a more portable, long term, solution.
79 .Pp
80 The functions in the API are split into two groups, those that build a
81 routing header and those that parse a received routing header.
82 We will describe the builder functions followed by the parser functions.
83 .Ss inet6_rth_space
84 The
85 .Fn inet6_rth_space
86 function returns the number of bytes required to hold a Routing Header
87 of the type, specified in the
88 .Fa type
89 argument and containing the number of addresses specified in the
90 .Fa segments
91 argument.
92 When the type is
93 .Dv IPV6_RTHDR_TYPE_0
94 the number of segments must be from 0 through 127.
95 Routing headers of type
96 .Dv IPV6_RTHDR_TYPE_2
97 contain only one segment, and are only used with Mobile IPv6.
98 The return value from this function is the number of bytes required to
99 store the routing header.
100 If the value 0 is returned then either the
101 route header type was not recognized or another error occurred.
102 .Ss inet6_rth_init
103 The
104 .Fn inet6_rth_init
105 function initializes the pre-allocated buffer pointed to by
106 .Fa bp
107 to contain a routing header of the specified type The
108 .Fa bp_len
109 argument is used to verify that the buffer is large enough.
110 The caller must allocate the buffer pointed to by bp.
111 The necessary buffer size should be determined by calling
112 .Fn inet6_rth_space
113 described in the previous sections.
114 .Pp
115 The
116 .Fn inet6_rth_init
117 function returns a pointer to
118 .Fa bp
119 on success and
120 .Dv NULL
121 when there is an error.
122 .Ss inet6_rth_add
123 The
124 .Fn inet6_rth_add
125 function adds the IPv6 address pointed to by
126 .Fa addr
127 to the end of the routing header being constructed.
128 .Pp
129 A successful addition results in the function returning 0, otherwise
130 \-1 is returned.
131 .Ss inet6_rth_reverse
132 The
133 .Fn inet6_rth_reverse
134 function takes a routing header, pointed to by the
135 argument
136 .Fa in ,
137 and writes a new routing header into the argument pointed to by
138 .Fa out .
139 The routing header at that sends datagrams along the reverse of that
140 route.
141 Both arguments are allowed to point to the same buffer meaning
142 that the reversal can occur in place.
143 .Pp
144 The return value of the function is 0 on success, or \-1 when
145 there is an error.
146 .\"
147 .Pp
148 The next set of functions operate on a routing header that the
149 application wants to parse.
150 In the usual case such a routing header
151 is received from the network, although these functions can also be
152 used with routing headers that the application itself created.
153 .Ss inet6_rth_segments
154 The
155 .Fn inet6_rth_segments
156 function returns the number of segments contained in the
157 routing header pointed to by
158 .Fa bp .
159 The return value is the number of segments contained in the routing
160 header, or \-1 if an error occurred.
161 It is not an error for 0 to be
162 returned as a routing header may contain 0 segments.
163 .\"
164 .Ss inet6_rth_getaddr
165 The
166 .Fn inet6_rth_getaddr
167 function is used to retrieve a single address from a routing header.
168 The
169 .Fa index
170 is the location in the routing header from which the application wants
171 to retrieve an address.
172 The
173 .Fa index
174 parameter must have a value between 0 and one less than the number of
175 segments present in the routing header.
176 The
177 .Fn inet6_rth_segments
178 function, described in the last section, should be used to determine
179 the total number of segments in the routing header.
180 The
181 .Fn inet6_rth_getaddr
182 function returns a pointer to an IPv6 address on success or
183 .Dv NULL
184 when an error has occurred.
185 .\"
186 .Sh EXAMPLES
187 RFC 3542 gives extensive examples in Section 21, Appendix B.
188 .Pp
189 KAME also provides examples in the advapitest directory of its kit.
190 .\"
191 .Sh DIAGNOSTICS
192 The
193 .Fn inet6_rth_space
194 and
195 .Fn inet6_rth_getaddr
196 functions return 0 on errors.
197 .Pp
198 The
199 .Fn inet6_rthdr_init
200 function returns
201 .Dv NULL
202 on error.
203 The
204 .Fn inet6_rth_add
205 and
206 .Fn inet6_rth_reverse
207 functions return 0 on success, or \-1 upon an error.
208 .\"
209 .Sh SEE ALSO
210 .Rs
211 .%A W. Stevens
212 .%A M. Thomas
213 .%A E. Nordmark
214 .%A T. Jinmei
215 .%T "Advanced Sockets API for IPv6"
216 .%N RFC 3542
217 .%D May 2003
218 .Re
219 .Rs
220 .%A S. Deering
221 .%A R. Hinden
222 .%T "Internet Protocol, Version 6 (IPv6) Specification"
223 .%N RFC 2460
224 .%D December 1998
225 .Re
226 .Sh HISTORY
227 The implementation first appeared in KAME advanced networking kit.