man3/netlink.3

   1 .\" This manpage copyright 1998 by Andi Kleen. Subject to the GPL.
   2 .\" Based on the original comments from Alexey Kuznetsov
   3 .\" $Id: netlink.3,v 1.1 1999/05/14 17:17:24 freitag Exp $
   4 .TH NETLINK 3 1999-05-14 "Linux Man Page" "Linux Programmer's Manual"
   5 .SH NAME
   6 netlink \- Netlink macros
   7 .SH SYNOPSIS
   8 .nf
   9 .\" FIXME what will glibc 2.1 use here?
  10 .B #include <asm/types.h>
  11 .br
  12 .B #include <linux/netlink.h>
  13 .br
  14 .BI "int NLMSG_ALIGN(size_t " len );
  15 .br
  16 .BI "int NLMSG_LENGTH(size_t " len );
  17 .br
  18 .BI "int NLMSG_SPACE(size_t " len );
  19 .br
  20 .BI "void *NLMSG_DATA(struct nlmsghdr *" nlh );
  21 .br
  22 .BI "struct nlmsghdr *NLMSG_NEXT(struct nlmsghdr *" nlh ", int " len );
  23 .br
  24 .BI "int NLMSG_OK(struct nlmsghdr *" nlh ", int " len );
  25 .br
  26 .BI "int NLMSG_PAYLOAD(struct nlmsghdr *" nlh ", int " len );
  27 .fi
  28 .SH DESCRIPTION
  29 .I netlink.h
  30 defines several standard macros to access or create a netlink datagram.
  31 They are similar in spirit to the macros defined in
  32 .BR cmsg (3)
  33 for auxiliary data. The buffer passed to and from a netlink socket should
  34 be only accessed using these macros.
  35 .TP
  36 .TP
  37 NLMSG_ALIGN
  38 Round the length of a netlink message up to align it properly.
  39 .TP
  40 NLMSG_LENGTH
  41 Gets the payload length as argument and returns the aligned length to store
  42 in the
  43 .B nlmsg_len
  44 field of the
  45 .IR nlmsghdr .
  46
  47 .TP
  48 NLMSG_SPACE
  49 Return the number of bytes a netlink message with payload of the passed length
  50 would occupy.
  51 .TP
  52 NLMSG_DATA
  53 Return a pointer to the payload associated with the passed
  54 .IR nlmsghdr .
  55 .TP
  56 .\" FIXME this is bizarre, maybe the interface should be fixed.
  57 NLMSG_NEXT
  58 Get the next
  59 .I nlmsghdr
  60 in a multipart message.
  61 The caller must check if the current nlmsghdr didn't have the NLMSG_DONE
  62 set \(em this function doesn't return NULL on end.
  63 The length parameter is an lvalue containing the remaining length
  64 of the message buffer.
  65 This macro decrements it by the length of the message header.
  66 .TP
  67 NLMSG_OK
  68 Return true if the netlink message is not truncated and ok to parse.
  69 .TP
  70 NLMSG_PAYLOAD
  71 Return the length of the payload associated with the
  72 .IR nlmsghdr .
  73
  74 .SH NOTES
  75 It is often better to use netlink via
  76 .B libnetlink
  77 than via the low level kernel interface.
  78
  79 .SH "SEE ALSO"
  80 .BR netlink (7)
  81 .PP
  82 and ftp://ftp.inr.ac.ru/ip-routing/iproute2* for libnetlink