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Diffstat (limited to 'man3/rtnetlink.3')
| -rw-r--r-- | man3/rtnetlink.3 | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/man3/rtnetlink.3 b/man3/rtnetlink.3 new file mode 100644 index 000000000..51b998a77 --- /dev/null +++ b/man3/rtnetlink.3 @@ -0,0 +1,115 @@ +.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>. +.\" Permission is granted to distribute possibly modified copies +.\" of this page provided the header is included verbatim, +.\" and in case of nontrivial modification author and date +.\" of the modification is added to the header. +.\" $Id: rtnetlink.3,v 1.2 1999/05/18 10:35:10 freitag Exp $ +.TH RTNETLINK 3 1999-05-14 "Linux Man Page" "Linux Programmer's Manual" +.SH NAME +rtnetlink \- Macros to manipuate rtnetlink messages +.SH SYNOPSIS +.B #include <asm/types.h> +.br +.B #include <linux/netlink.h> +.br +.B #include <linux/rtnetlink.h> +.br +.B #include <sys/socket.h> + +.BI "rtnetlink_socket = socket(PF_NETLINK, int " socket_type ", NETLINK_ROUTE);" +.br +.B int RTA_OK(struct rtattr *rta, int rtabuflen); +.br +.B void *RTA_DATA(struct rtattr *rta); +.br +.B unsigned int RTA_PAYLOAD(struct rtattr *rta); +.br +.B struct rtattr *RTA_NEXT(struct rtattr *rta, unsigned int rtabuflen); +.br +.B unsigned int RTA_LENGTH(unsigned int length); +.br +.B unsigned int RTA_SPACE(unsigned int length); +.br +.SH DESCRIPTION +All +.BR rtnetlink (7) +messages consist of a +.BR netlink (7) +message header and appended attributes. The attributes should be only +manipulated using the macros provided here. + +.PP +.BI RTA_OK( rta ", " attrlen ) +returns true if +.I rta +points to a valid routing attribute; +.I 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 +.I attrlen +is non-zero. +.br +.BI RTA_DATA( rta ) +returns a pointer to the start of this attribute's data. +.br +.BI RTA_PAYLOAD( rta ) +returns the length of this attribute's data. +.br +.BI RTA_NEXT( rta ", " attrlen ) +gets the next attribute after +.IR rta . +Calling this macro will update +.IR attrlen . +You should use +.B RTA_OK +to check for the validity of the returned pointer. +.br +.BI RTA_LENGTH( len ) +returns the length which is required for +.I len +bytes of data plus the header. +.br +.BI RTA_SPACE( len ) +returns the amount of space which will be needed in the message with +.I len +bytes of data. + +.SH EXAMPLE +.\" XXX would be better to use libnetlink here + +Creating a rtnetlink message to set a MTU of a device. +.nf + 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); +.fi + +.SH BUGS +This manual page is lacking and incomplete. + +.SH "SEE ALSO" +.BR netlink (3), +.BR netlink (7), +.BR rtnetlink (7) |