View Source: rtnetlink(3) - Waikato Linux Users Group

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RTNETLINK
!!!RTNETLINK
NAME
SYNOPSIS
DESCRIPTION
EXAMPLE
BUGS
SEE ALSO
----
!!NAME


rtnetlink - Macros to manipuate rtnetlink messages
!!SYNOPSIS


__#include __
#include __
#include __
#include __


__rtnetlink_socket = socket(PF_NETLINK, int__
''socket_type''__, NETLINK_ROUTE);
int RTA_OK(struct rtattr *rta, int rtabuflen);
void *RTA_DATA(struct rtattr *rta);
unsigned int RTA_PAYLOAD(struct rtattr *rta);
struct rtattr *RTA_NEXT(struct rtattr *rta, unsigned int
rtabuflen);
unsigned int RTA_LENGTH(unsigned int length);
unsigned int RTA_SPACE(unsigned int
length);__
!!DESCRIPTION


All rtnetlink(7) messages consist of a
netlink(7) message header and appended attributes.
The attributes should be only manipulated using the macros
provided here.


__RTA_OK(__''rta''__,__ ''attrlen''__)__
returns true if ''rta'' points to a valid routing
attribute; ''attrlen'' is the running length of the
attribute buffer. When not true then you must assume there
are no more attributes in the message, even if
''attrlen'' is non-zero.__
RTA_DATA(__''rta''__)__ returns a pointer to the
start of this attribute's data.__
RTA_PAYLOAD(__''rta''__)__ returns the length of
this attribute's data.__
RTA_NEXT(__''rta''__,__ ''attrlen''__)__ gets
the next attribute after ''rta''. Calling this macro will
update ''attrlen''. You should use __RTA_OK__ to check
for the validity of the returned pointer.__
RTA_LENGTH(__''len''__)__ returns the length which
is required for ''len'' bytes of data plus the
header.__
RTA_SPACE(__''len''__)__ returns the amount of space
which will be needed in the message with ''len'' bytes of
data.
!!EXAMPLE


Creating a rtnetlink message to set a MTU of a
device.


     struct {
struct nlmsghdr nh;
struct ifinfomsg   if;
char           attrbuf[[512];
} req;
struct rtattr *rta;
unsigned int mtu = 1000;
int rtnetlink_sk = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
memset(
!!BUGS


This manual page is lacking and incomplete.
!!SEE ALSO


rtnetlink(7), netlink(7),
netlink(3)
----

3 pages link to rtnetlink(3):

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Last edited on Tuesday, June 4, 2002 12:24:33 am by "perry"

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