src/libhydra/plugins/kernel_netlink/kernel_netlink_shared.h

   1 /*
   2  * Copyright (C) 2008 Tobias Brunner
   3  * Hochschule fuer Technik Rapperswil
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the
   7  * Free Software Foundation; either version 2 of the License, or (at your
   8  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  12  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * for more details.
  14  */
  15
  16 #ifndef KERNEL_NETLINK_SHARED_H_
  17 #define KERNEL_NETLINK_SHARED_H_
  18
  19 #include <library.h>
  20
  21 #include <linux/rtnetlink.h>
  22
  23 /**
  24  * General purpose netlink buffer.
  25  *
  26  * 1024 byte is currently sufficient for all operations. Some platform
  27  * require an enforced aligment to four bytes (e.g. ARM).
  28  */
  29 typedef union {
  30         struct nlmsghdr hdr;
  31         u_char bytes[1024];
  32 } netlink_buf_t __attribute__((aligned(RTA_ALIGNTO)));
  33
  34 typedef struct netlink_socket_t netlink_socket_t;
  35
  36 /**
  37  * Wrapper around a netlink socket.
  38  */
  39 struct netlink_socket_t {
  40
  41         /**
  42          * Send a netlink message and wait for a reply.
  43          *
  44          * @param       in              netlink message to send
  45          * @param       out     received netlink message
  46          * @param       out_len length of the received message
  47          */
  48         status_t (*send)(netlink_socket_t *this, struct nlmsghdr *in,
  49                                          struct nlmsghdr **out, size_t *out_len);
  50
  51         /**
  52          * Send a netlink message and wait for its acknowledge.
  53          *
  54          * @param       in              netlink message to send
  55          */
  56         status_t (*send_ack)(netlink_socket_t *this, struct nlmsghdr *in);
  57
  58         /**
  59          * Destroy the socket.
  60          */
  61         void (*destroy)(netlink_socket_t *this);
  62 };
  63
  64 /**
  65  * Create a netlink_socket_t object.
  66  *
  67  * @param protocol      protocol type (e.g. NETLINK_XFRM or NETLINK_ROUTE)
  68  * @param names         optional enum names for Netlink messages
  69  * @param parallel      support parallel queries on this Netlink socket
  70  */
  71 netlink_socket_t *netlink_socket_create(int protocol, enum_name_t *names,
  72                                                                                 bool parallel);
  73
  74 /**
  75  * Creates an rtattr and adds it to the given netlink message.
  76  *
  77  * @param hdr                   netlink message
  78  * @param rta_type              type of the rtattr
  79  * @param data                  data to add to the rtattr
  80  * @param buflen                length of the netlink message buffer
  81  */
  82 void netlink_add_attribute(struct nlmsghdr *hdr, int rta_type, chunk_t data,
  83                                                    size_t buflen);
  84
  85 /**
  86  * Reserve space in a netlink message for given size and type, returning buffer.
  87  *
  88  * @param hdr                   netlink message
  89  * @param buflen                size of full netlink buffer
  90  * @param type                  RTA type
  91  * @param len                   length of RTA data
  92  * @return                              buffer to len bytes of attribute data, NULL on error
  93  */
  94 void* netlink_reserve(struct nlmsghdr *hdr, int buflen, int type, int len);
  95
  96 #endif /* KERNEL_NETLINK_SHARED_H_ */