RTNETLINK

RTNETLINK

NAME SYNOPSIS DESCRIPTION EXAMPLE BUGS SEE ALSO

NAME

rtnetlink - Macros to manipuate rtnetlink messages

SYNOPSIS

#include

1. include __
2. include __
3. 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)