Comtrol eCos - Manual (Page 542)

Chapter 38. TCP/IP Library Reference
inet6_rthdr_getflags(const struct cmsghdr *cmsg, int index);
DESCRIPTION
RFC2292 IPv6 advanced API defines eight functions that the application
calls to build and examine a Routing header. Four functions build a
Routing header:
inet6_rthdr_space() return #bytes required for ancillary data
inet6_rthdr_init() initialize ancillary data for Routing header
inet6_rthdr_add() add IPv6 address & flags to Routing header
inet6_rthdr_lasthop() specify the flags for the final hop
Four functions deal with a returned Routing header:
inet6_rthdr_reverse() reverse a Routing header
inet6_rthdr_segments() return #segments in a Routing header
inet6_rthdr_getaddr() fetch one address from a Routing header
inet6_rthdr_getflags() fetch one flag from a Routing header
The function prototypes for these functions are all in the < netinet/in.h>
header.
inet6_rthdr_space
This function returns the number of bytes required to hold a Routing
header of the specified type containing the specified number of segments
(addresses). For an IPv6 Type 0 Routing header, the number of segments
must be between 1 and 23, inclusive. The return value includes the size
of the cmsghdr structure that precedes the Routing header, and any
required padding.
If the return value is 0, then either the type of the Routing header is
not supported by this implementation or the number of segments is invalid
for this type of Routing header.
Note: This function returns the size but does not allocate the space
required for the ancillary data. This allows an application to allocate
a larger buffer, if other ancillary data objects are desired, since all
the ancillary data objects must be specified to sendmsg(2) as a single
msg_control buffer.
inet6_rthdr_init
This function initializes the buffer pointed to by bp to contain a
cmsghdr structure followed by a Routing header of the specified type.
The cmsg_len member of the cmsghdr structure is initialized to the size
of the structure plus the amount of space required by the Routing header.
The cmsg_level and cmsg_type members are also initialized as required.
The caller must allocate the buffer and its size can be determined by
calling inet6_rthdr_space().
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