Developer's Daily | Unix by Example |
main | java | perl | unix | dev directory | web log |
rtnetlink ? Macros to manipuate rtnetlink messages |
#include <asm/types.h> rtnetlink_socket = socket(PF_NETLINK, int
socket_type, NETLINK_ROUTE); |
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. |
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(&req, 0, sizeof(req)); |
|||||
req.nh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)); |
|||||
req.nh.nlmsg_flags = NLM_F_REQUEST; |
|||||
req.nh.nlmsg_type = RTML_NEWLINK; |
|||||
req.if.ifi_family = AF_UNSPEC; |
|||||
req.if.ifi_index = INTERFACE_INDEX; |
|||||
req.if.ifi_change = 0xffffffff; /* ???*/ |
|||||
rta = (struct rtattr *)(((char *) &req) + |
|||||
NLMSG_ALIGN(n->nlmsg_len)); |
|||||
rta->rta_type = IFLA_MTU; |
|||||
rta->rta_len = sizeof(unsigned int); |
|||||
req.n.nlmsg_len = NLMSG_ALIGN(req.n.nlmsg_len) + |
|||||
RTA_LENGTH(sizeof(mtu)); |
|||||
memcpy(RTA_DATA(rta), &mtu, sizeof (mtu)); |
|||||
send(rtnetlink_sk, &req, req.n.nlmsg_len); |
This manual page is lacking and incomplete. |
rtnetlink(7), netlink(7), netlink(3) |