| .\" This manpage copyright 1998 by Andi Kleen. |
| .\" |
| .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE) |
| .\" Subject to the GPL. |
| .\" %%%LICENSE_END |
| .\" |
| .\" Based on the original comments from Alexey Kuznetsov |
| .\" $Id: netlink.3,v 1.1 1999/05/14 17:17:24 freitag Exp $ |
| .\" |
| .TH NETLINK 3 2014-03-20 "GNU" "Linux Programmer's Manual" |
| .SH NAME |
| netlink \- Netlink macros |
| .SH SYNOPSIS |
| .nf |
| .B #include <asm/types.h> |
| .B #include <linux/netlink.h> |
| .PP |
| .BI "int NLMSG_ALIGN(size_t " len ); |
| .BI "int NLMSG_LENGTH(size_t " len ); |
| .BI "int NLMSG_SPACE(size_t " len ); |
| .BI "void *NLMSG_DATA(struct nlmsghdr *" nlh ); |
| .BI "struct nlmsghdr *NLMSG_NEXT(struct nlmsghdr *" nlh ", int " len ); |
| .BI "int NLMSG_OK(struct nlmsghdr *" nlh ", int " len ); |
| .BI "int NLMSG_PAYLOAD(struct nlmsghdr *" nlh ", int " len ); |
| .fi |
| .SH DESCRIPTION |
| .I <linux/netlink.h> |
| defines several standard macros to access or create a netlink datagram. |
| They are similar in spirit to the macros defined in |
| .BR cmsg (3) |
| for auxiliary data. |
| The buffer passed to and from a netlink socket should |
| be accessed using only these macros. |
| .TP |
| .BR NLMSG_ALIGN () |
| Round the length of a netlink message up to align it properly. |
| .TP |
| .BR NLMSG_LENGTH () |
| Given the payload length, |
| .IR len , |
| this macro returns the aligned length to store in the |
| .I nlmsg_len |
| field of the |
| .IR nlmsghdr . |
| .TP |
| .BR NLMSG_SPACE () |
| Return the number of bytes that a netlink message with payload of |
| .I len |
| would occupy. |
| .TP |
| .BR NLMSG_DATA () |
| Return a pointer to the payload associated with the passed |
| .IR nlmsghdr . |
| .TP |
| .\" this is bizarre, maybe the interface should be fixed. |
| .BR NLMSG_NEXT () |
| Get the next |
| .I nlmsghdr |
| in a multipart message. |
| The caller must check if the current |
| .I nlmsghdr |
| didn't have the |
| .B NLMSG_DONE |
| set\(emthis function doesn't return NULL on end. |
| The |
| .I len |
| argument is an lvalue containing the remaining length |
| of the message buffer. |
| This macro decrements it by the length of the message header. |
| .TP |
| .BR NLMSG_OK () |
| Return true if the netlink message is not truncated and |
| is in a form suitable for parsing. |
| .TP |
| .BR NLMSG_PAYLOAD () |
| Return the length of the payload associated with the |
| .IR nlmsghdr . |
| .SH CONFORMING TO |
| These macros are nonstandard Linux extensions. |
| .SH NOTES |
| It is often better to use netlink via |
| .I libnetlink |
| than via the low-level kernel interface. |
| .SH SEE ALSO |
| .BR libnetlink (3), |
| .BR netlink (7) |
