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netlink.h

#ifndef __NET_NETLINK_H
#define __NET_NETLINK_H

#include <linux/types.h>
#include <linux/netlink.h>
#include <linux/jiffies.h>

/* ========================================================================
 *         Netlink Messages and Attributes Interface (As Seen On TV)
 * ------------------------------------------------------------------------
 *                          Messages Interface
 * ------------------------------------------------------------------------
 *
 * Message Format:
 *    <--- nlmsg_total_size(payload)  --->
 *    <-- nlmsg_msg_size(payload) ->
 *   +----------+- - -+-------------+- - -+-------- - -
 *   | nlmsghdr | Pad |   Payload   | Pad | nlmsghdr
 *   +----------+- - -+-------------+- - -+-------- - -
 *   nlmsg_data(nlh)---^                   ^
 *   nlmsg_next(nlh)-----------------------+
 *
 * Payload Format:
 *    <---------------------- nlmsg_len(nlh) --------------------->
 *    <------ hdrlen ------>       <- nlmsg_attrlen(nlh, hdrlen) ->
 *   +----------------------+- - -+--------------------------------+
 *   |     Family Header    | Pad |           Attributes           |
 *   +----------------------+- - -+--------------------------------+
 *   nlmsg_attrdata(nlh, hdrlen)---^
 *
 * Data Structures:
 *   struct nlmsghdr                netlink message header
 *
 * Message Construction:
 *   nlmsg_new()              create a new netlink message
 *   nlmsg_put()              add a netlink message to an skb
 *   nlmsg_put_answer()             callback based nlmsg_put()
 *   nlmsg_end()              finanlize netlink message
 *   nlmsg_get_pos()                return current position in message
 *   nlmsg_trim()             trim part of message
 *   nlmsg_cancel()                 cancel message construction
 *   nlmsg_free()             free a netlink message
 *
 * Message Sending:
 *   nlmsg_multicast()              multicast message to several groups
 *   nlmsg_unicast()                unicast a message to a single socket
 *   nlmsg_notify()                 send notification message
 *
 * Message Length Calculations:
 *   nlmsg_msg_size(payload)        length of message w/o padding
 *   nlmsg_total_size(payload)            length of message w/ padding
 *   nlmsg_padlen(payload)          length of padding at tail
 *
 * Message Payload Access:
 *   nlmsg_data(nlh)                head of message payload
 *   nlmsg_len(nlh)                 length of message payload
 *   nlmsg_attrdata(nlh, hdrlen)    head of attributes data
 *   nlmsg_attrlen(nlh, hdrlen)           length of attributes data
 *
 * Message Parsing:
 *   nlmsg_ok(nlh, remaining)       does nlh fit into remaining bytes?
 *   nlmsg_next(nlh, remaining)           get next netlink message
 *   nlmsg_parse()                  parse attributes of a message
 *   nlmsg_find_attr()              find an attribute in a message
 *   nlmsg_for_each_msg()           loop over all messages
 *   nlmsg_validate()               validate netlink message incl. attrs
 *   nlmsg_for_each_attr()          loop over all attributes
 *
 * Misc:
 *   nlmsg_report()                 report back to application?
 *
 * ------------------------------------------------------------------------
 *                          Attributes Interface
 * ------------------------------------------------------------------------
 *
 * Attribute Format:
 *    <------- nla_total_size(payload) ------->
 *    <---- nla_attr_size(payload) ----->
 *   +----------+- - -+- - - - - - - - - +- - -+-------- - -
 *   |  Header  | Pad |     Payload      | Pad |  Header
 *   +----------+- - -+- - - - - - - - - +- - -+-------- - -
 *                     <- nla_len(nla) ->      ^
 *   nla_data(nla)----^                        |
 *   nla_next(nla)-----------------------------'
 *
 * Data Structures:
 *   struct nlattr                  netlink attribute header
 *
 * Attribute Construction:
 *   nla_reserve(skb, type, len)    reserve room for an attribute
 *   nla_reserve_nohdr(skb, len)    reserve room for an attribute w/o hdr
 *   nla_put(skb, type, len, data)  add attribute to skb
 *   nla_put_nohdr(skb, len, data)  add attribute w/o hdr
 *
 * Attribute Construction for Basic Types:
 *   nla_put_u8(skb, type, value)   add u8 attribute to skb
 *   nla_put_u16(skb, type, value)  add u16 attribute to skb
 *   nla_put_u32(skb, type, value)  add u32 attribute to skb
 *   nla_put_u64(skb, type, value)  add u64 attribute to skb
 *   nla_put_string(skb, type, str) add string attribute to skb
 *   nla_put_flag(skb, type)        add flag attribute to skb
 *   nla_put_msecs(skb, type, jiffies)    add msecs attribute to skb
 *
 * Exceptions Based Attribute Construction:
 *   NLA_PUT(skb, type, len, data)  add attribute to skb
 *   NLA_PUT_U8(skb, type, value)   add u8 attribute to skb
 *   NLA_PUT_U16(skb, type, value)  add u16 attribute to skb
 *   NLA_PUT_U32(skb, type, value)  add u32 attribute to skb
 *   NLA_PUT_U64(skb, type, value)  add u64 attribute to skb
 *   NLA_PUT_STRING(skb, type, str) add string attribute to skb
 *   NLA_PUT_FLAG(skb, type)        add flag attribute to skb
 *   NLA_PUT_MSECS(skb, type, jiffies)    add msecs attribute to skb
 *
 *   The meaning of these functions is equal to their lower case
 *   variants but they jump to the label nla_put_failure in case
 *   of a failure.
 *
 * Nested Attributes Construction:
 *   nla_nest_start(skb, type)            start a nested attribute
 *   nla_nest_end(skb, nla)         finalize a nested attribute
 *   nla_nest_compat_start(skb, type,     start a nested compat attribute
 *                   len, data)
 *   nla_nest_compat_end(skb, type) finalize a nested compat attribute
 *   nla_nest_cancel(skb, nla)            cancel nested attribute construction
 *
 * Attribute Length Calculations:
 *   nla_attr_size(payload)         length of attribute w/o padding
 *   nla_total_size(payload)        length of attribute w/ padding
 *   nla_padlen(payload)            length of padding
 *
 * Attribute Payload Access:
 *   nla_data(nla)                  head of attribute payload
 *   nla_len(nla)             length of attribute payload
 *
 * Attribute Payload Access for Basic Types:
 *   nla_get_u8(nla)                get payload for a u8 attribute
 *   nla_get_u16(nla)               get payload for a u16 attribute
 *   nla_get_u32(nla)               get payload for a u32 attribute
 *   nla_get_u64(nla)               get payload for a u64 attribute
 *   nla_get_flag(nla)              return 1 if flag is true
 *   nla_get_msecs(nla)             get payload for a msecs attribute
 *
 * Attribute Misc:
 *   nla_memcpy(dest, nla, count)   copy attribute into memory
 *   nla_memcmp(nla, data, size)    compare attribute with memory area
 *   nla_strlcpy(dst, nla, size)    copy attribute to a sized string
 *   nla_strcmp(nla, str)           compare attribute with string
 *
 * Attribute Parsing:
 *   nla_ok(nla, remaining)         does nla fit into remaining bytes?
 *   nla_next(nla, remaining)       get next netlink attribute
 *   nla_validate()                 validate a stream of attributes
 *   nla_validate_nested()          validate a stream of nested attributes
 *   nla_find()                     find attribute in stream of attributes
 *   nla_find_nested()              find attribute in nested attributes
 *   nla_parse()              parse and validate stream of attrs
 *   nla_parse_nested()             parse nested attribuets
 *   nla_parse_nested_compat()            parse nested compat attributes
 *   nla_for_each_attr()            loop over all attributes
 *   nla_for_each_nested()          loop over the nested attributes
 *=========================================================================
 */

 /**
  * Standard attribute types to specify validation policy
  */
enum {
      NLA_UNSPEC,
      NLA_U8,
      NLA_U16,
      NLA_U32,
      NLA_U64,
      NLA_STRING,
      NLA_FLAG,
      NLA_MSECS,
      NLA_NESTED,
      NLA_NESTED_COMPAT,
      NLA_NUL_STRING,
      NLA_BINARY,
      __NLA_TYPE_MAX,
};

#define NLA_TYPE_MAX (__NLA_TYPE_MAX - 1)

/**
 * struct nla_policy - attribute validation policy
 * @type: Type of attribute or NLA_UNSPEC
 * @len: Type specific length of payload
 *
 * Policies are defined as arrays of this struct, the array must be
 * accessible by attribute type up to the highest identifier to be expected.
 *
 * Meaning of `len' field:
 *    NLA_STRING           Maximum length of string
 *    NLA_NUL_STRING       Maximum length of string (excluding NUL)
 *    NLA_FLAG             Unused
 *    NLA_BINARY           Maximum length of attribute payload
 *    NLA_NESTED_COMPAT    Exact length of structure payload
 *    All other            Exact length of attribute payload
 *
 * Example:
 * static struct nla_policy my_policy[ATTR_MAX+1] __read_mostly = {
 *    [ATTR_FOO] = { .type = NLA_U16 },
 *    [ATTR_BAR] = { .type = NLA_STRING, .len = BARSIZ },
 *    [ATTR_BAZ] = { .len = sizeof(struct mystruct) },
 * };
 */
00208 struct nla_policy {
      u16         type;
      u16         len;
};

/**
 * struct nl_info - netlink source information
 * @nlh: Netlink message header of original request
 * @pid: Netlink PID of requesting application
 */
00218 struct nl_info {
      struct nlmsghdr         *nlh;
      u32               pid;
};

extern int        netlink_rcv_skb(struct sk_buff *skb,
                              int (*cb)(struct sk_buff *,
                                      struct nlmsghdr *));
extern int        nlmsg_notify(struct sock *sk, struct sk_buff *skb,
                             u32 pid, unsigned int group, int report,
                             gfp_t flags);

extern int        nla_validate(struct nlattr *head, int len, int maxtype,
                             const struct nla_policy *policy);
extern int        nla_parse(struct nlattr *tb[], int maxtype,
                          struct nlattr *head, int len,
                          const struct nla_policy *policy);
extern struct nlattr *  nla_find(struct nlattr *head, int len, int attrtype);
extern size_t           nla_strlcpy(char *dst, const struct nlattr *nla,
                            size_t dstsize);
extern int        nla_memcpy(void *dest, struct nlattr *src, int count);
extern int        nla_memcmp(const struct nlattr *nla, const void *data,
                           size_t size);
extern int        nla_strcmp(const struct nlattr *nla, const char *str);
extern struct nlattr *  __nla_reserve(struct sk_buff *skb, int attrtype,
                              int attrlen);
extern void *           __nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
extern struct nlattr *  nla_reserve(struct sk_buff *skb, int attrtype,
                            int attrlen);
extern void *           nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
extern void       __nla_put(struct sk_buff *skb, int attrtype,
                          int attrlen, const void *data);
extern void       __nla_put_nohdr(struct sk_buff *skb, int attrlen,
                              const void *data);
extern int        nla_put(struct sk_buff *skb, int attrtype,
                        int attrlen, const void *data);
extern int        nla_put_nohdr(struct sk_buff *skb, int attrlen,
                              const void *data);

/**************************************************************************
 * Netlink Messages
 **************************************************************************/

/**
 * nlmsg_msg_size - length of netlink message not including padding
 * @payload: length of message payload
 */
static inline int nlmsg_msg_size(int payload)
{
      return NLMSG_HDRLEN + payload;
}

/**
 * nlmsg_total_size - length of netlink message including padding
 * @payload: length of message payload
 */
static inline int nlmsg_total_size(int payload)
{
      return NLMSG_ALIGN(nlmsg_msg_size(payload));
}

/**
 * nlmsg_padlen - length of padding at the message's tail
 * @payload: length of message payload
 */
static inline int nlmsg_padlen(int payload)
{
      return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
}

/**
 * nlmsg_data - head of message payload
 * @nlh: netlink messsage header
 */
static inline void *nlmsg_data(const struct nlmsghdr *nlh)
{
      return (unsigned char *) nlh + NLMSG_HDRLEN;
}

/**
 * nlmsg_len - length of message payload
 * @nlh: netlink message header
 */
static inline int nlmsg_len(const struct nlmsghdr *nlh)
{
      return nlh->nlmsg_len - NLMSG_HDRLEN;
}

/**
 * nlmsg_attrdata - head of attributes data
 * @nlh: netlink message header
 * @hdrlen: length of family specific header
 */
static inline struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh,
                                  int hdrlen)
{
      unsigned char *data = nlmsg_data(nlh);
      return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
}

/**
 * nlmsg_attrlen - length of attributes data
 * @nlh: netlink message header
 * @hdrlen: length of family specific header
 */
static inline int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
{
      return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
}

/**
 * nlmsg_ok - check if the netlink message fits into the remaining bytes
 * @nlh: netlink message header
 * @remaining: number of bytes remaining in message stream
 */
static inline int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
{
      return (remaining >= sizeof(struct nlmsghdr) &&
            nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
            nlh->nlmsg_len <= remaining);
}

/**
 * nlmsg_next - next netlink message in message stream
 * @nlh: netlink message header
 * @remaining: number of bytes remaining in message stream
 *
 * Returns the next netlink message in the message stream and
 * decrements remaining by the size of the current message.
 */
static inline struct nlmsghdr *nlmsg_next(struct nlmsghdr *nlh, int *remaining)
{
      int totlen = NLMSG_ALIGN(nlh->nlmsg_len);

      *remaining -= totlen;

      return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
}

/**
 * nlmsg_parse - parse attributes of a netlink message
 * @nlh: netlink message header
 * @hdrlen: length of family specific header
 * @tb: destination array with maxtype+1 elements
 * @maxtype: maximum attribute type to be expected
 * @policy: validation policy
 *
 * See nla_parse()
 */
static inline int nlmsg_parse(struct nlmsghdr *nlh, int hdrlen,
                        struct nlattr *tb[], int maxtype,
                        const struct nla_policy *policy)
{
      if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
            return -EINVAL;

      return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
                   nlmsg_attrlen(nlh, hdrlen), policy);
}

/**
 * nlmsg_find_attr - find a specific attribute in a netlink message
 * @nlh: netlink message header
 * @hdrlen: length of familiy specific header
 * @attrtype: type of attribute to look for
 *
 * Returns the first attribute which matches the specified type.
 */
static inline struct nlattr *nlmsg_find_attr(struct nlmsghdr *nlh,
                                   int hdrlen, int attrtype)
{
      return nla_find(nlmsg_attrdata(nlh, hdrlen),
                  nlmsg_attrlen(nlh, hdrlen), attrtype);
}

/**
 * nlmsg_validate - validate a netlink message including attributes
 * @nlh: netlinket message header
 * @hdrlen: length of familiy specific header
 * @maxtype: maximum attribute type to be expected
 * @policy: validation policy
 */
static inline int nlmsg_validate(struct nlmsghdr *nlh, int hdrlen, int maxtype,
                         const struct nla_policy *policy)
{
      if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
            return -EINVAL;

      return nla_validate(nlmsg_attrdata(nlh, hdrlen),
                      nlmsg_attrlen(nlh, hdrlen), maxtype, policy);
}

/**
 * nlmsg_report - need to report back to application?
 * @nlh: netlink message header
 *
 * Returns 1 if a report back to the application is requested.
 */
static inline int nlmsg_report(struct nlmsghdr *nlh)
{
      return !!(nlh->nlmsg_flags & NLM_F_ECHO);
}

/**
 * nlmsg_for_each_attr - iterate over a stream of attributes
 * @pos: loop counter, set to current attribute
 * @nlh: netlink message header
 * @hdrlen: length of familiy specific header
 * @rem: initialized to len, holds bytes currently remaining in stream
 */
#define nlmsg_for_each_attr(pos, nlh, hdrlen, rem) \
      nla_for_each_attr(pos, nlmsg_attrdata(nlh, hdrlen), \
                    nlmsg_attrlen(nlh, hdrlen), rem)

#if 0
/* FIXME: Enable once all users have been converted */

/**
 * __nlmsg_put - Add a new netlink message to an skb
 * @skb: socket buffer to store message in
 * @pid: netlink process id
 * @seq: sequence number of message
 * @type: message type
 * @payload: length of message payload
 * @flags: message flags
 *
 * The caller is responsible to ensure that the skb provides enough
 * tailroom for both the netlink header and payload.
 */
static inline struct nlmsghdr *__nlmsg_put(struct sk_buff *skb, u32 pid,
                                 u32 seq, int type, int payload,
                                 int flags)
{
      struct nlmsghdr *nlh;

      nlh = (struct nlmsghdr *) skb_put(skb, nlmsg_total_size(payload));
      nlh->nlmsg_type = type;
      nlh->nlmsg_len = nlmsg_msg_size(payload);
      nlh->nlmsg_flags = flags;
      nlh->nlmsg_pid = pid;
      nlh->nlmsg_seq = seq;

      memset((unsigned char *) nlmsg_data(nlh) + payload, 0,
             nlmsg_padlen(payload));

      return nlh;
}
#endif

/**
 * nlmsg_put - Add a new netlink message to an skb
 * @skb: socket buffer to store message in
 * @pid: netlink process id
 * @seq: sequence number of message
 * @type: message type
 * @payload: length of message payload
 * @flags: message flags
 *
 * Returns NULL if the tailroom of the skb is insufficient to store
 * the message header and payload.
 */
static inline struct nlmsghdr *nlmsg_put(struct sk_buff *skb, u32 pid, u32 seq,
                               int type, int payload, int flags)
{
      if (unlikely(skb_tailroom(skb) < nlmsg_total_size(payload)))
            return NULL;

      return __nlmsg_put(skb, pid, seq, type, payload, flags);
}

/**
 * nlmsg_put_answer - Add a new callback based netlink message to an skb
 * @skb: socket buffer to store message in
 * @cb: netlink callback
 * @type: message type
 * @payload: length of message payload
 * @flags: message flags
 *
 * Returns NULL if the tailroom of the skb is insufficient to store
 * the message header and payload.
 */
static inline struct nlmsghdr *nlmsg_put_answer(struct sk_buff *skb,
                                    struct netlink_callback *cb,
                                    int type, int payload,
                                    int flags)
{
      return nlmsg_put(skb, NETLINK_CB(cb->skb).pid, cb->nlh->nlmsg_seq,
                   type, payload, flags);
}

/**
 * nlmsg_new - Allocate a new netlink message
 * @payload: size of the message payload
 * @flags: the type of memory to allocate.
 *
 * Use NLMSG_DEFAULT_SIZE if the size of the payload isn't known
 * and a good default is needed.
 */
static inline struct sk_buff *nlmsg_new(size_t payload, gfp_t flags)
{
      return alloc_skb(nlmsg_total_size(payload), flags);
}

/**
 * nlmsg_end - Finalize a netlink message
 * @skb: socket buffer the message is stored in
 * @nlh: netlink message header
 *
 * Corrects the netlink message header to include the appeneded
 * attributes. Only necessary if attributes have been added to
 * the message.
 *
 * Returns the total data length of the skb.
 */
static inline int nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh)
{
      nlh->nlmsg_len = skb_tail_pointer(skb) - (unsigned char *)nlh;

      return skb->len;
}

/**
 * nlmsg_get_pos - return current position in netlink message
 * @skb: socket buffer the message is stored in
 *
 * Returns a pointer to the current tail of the message.
 */
static inline void *nlmsg_get_pos(struct sk_buff *skb)
{
      return skb_tail_pointer(skb);
}

/**
 * nlmsg_trim - Trim message to a mark
 * @skb: socket buffer the message is stored in
 * @mark: mark to trim to
 *
 * Trims the message to the provided mark. Returns -1.
 */
static inline int nlmsg_trim(struct sk_buff *skb, const void *mark)
{
      if (mark)
            skb_trim(skb, (unsigned char *) mark - skb->data);

      return -1;
}

/**
 * nlmsg_cancel - Cancel construction of a netlink message
 * @skb: socket buffer the message is stored in
 * @nlh: netlink message header
 *
 * Removes the complete netlink message including all
 * attributes from the socket buffer again. Returns -1.
 */
static inline int nlmsg_cancel(struct sk_buff *skb, struct nlmsghdr *nlh)
{
      return nlmsg_trim(skb, nlh);
}

/**
 * nlmsg_free - free a netlink message
 * @skb: socket buffer of netlink message
 */
static inline void nlmsg_free(struct sk_buff *skb)
{
      kfree_skb(skb);
}

/**
 * nlmsg_multicast - multicast a netlink message
 * @sk: netlink socket to spread messages to
 * @skb: netlink message as socket buffer
 * @pid: own netlink pid to avoid sending to yourself
 * @group: multicast group id
 * @flags: allocation flags
 */
static inline int nlmsg_multicast(struct sock *sk, struct sk_buff *skb,
                          u32 pid, unsigned int group, gfp_t flags)
{
      int err;

      NETLINK_CB(skb).dst_group = group;

      err = netlink_broadcast(sk, skb, pid, group, flags);
      if (err > 0)
            err = 0;

      return err;
}

/**
 * nlmsg_unicast - unicast a netlink message
 * @sk: netlink socket to spread message to
 * @skb: netlink message as socket buffer
 * @pid: netlink pid of the destination socket
 */
static inline int nlmsg_unicast(struct sock *sk, struct sk_buff *skb, u32 pid)
{
      int err;

      err = netlink_unicast(sk, skb, pid, MSG_DONTWAIT);
      if (err > 0)
            err = 0;

      return err;
}

/**
 * nlmsg_for_each_msg - iterate over a stream of messages
 * @pos: loop counter, set to current message
 * @head: head of message stream
 * @len: length of message stream
 * @rem: initialized to len, holds bytes currently remaining in stream
 */
#define nlmsg_for_each_msg(pos, head, len, rem) \
      for (pos = head, rem = len; \
           nlmsg_ok(pos, rem); \
           pos = nlmsg_next(pos, &(rem)))

/**************************************************************************
 * Netlink Attributes
 **************************************************************************/

/**
 * nla_attr_size - length of attribute not including padding
 * @payload: length of payload
 */
static inline int nla_attr_size(int payload)
{
      return NLA_HDRLEN + payload;
}

/**
 * nla_total_size - total length of attribute including padding
 * @payload: length of payload
 */
static inline int nla_total_size(int payload)
{
      return NLA_ALIGN(nla_attr_size(payload));
}

/**
 * nla_padlen - length of padding at the tail of attribute
 * @payload: length of payload
 */
static inline int nla_padlen(int payload)
{
      return nla_total_size(payload) - nla_attr_size(payload);
}

/**
 * nla_type - attribute type
 * @nla: netlink attribute
 */
static inline int nla_type(const struct nlattr *nla)
{
      return nla->nla_type & NLA_TYPE_MASK;
}

/**
 * nla_data - head of payload
 * @nla: netlink attribute
 */
static inline void *nla_data(const struct nlattr *nla)
{
      return (char *) nla + NLA_HDRLEN;
}

/**
 * nla_len - length of payload
 * @nla: netlink attribute
 */
static inline int nla_len(const struct nlattr *nla)
{
      return nla->nla_len - NLA_HDRLEN;
}

/**
 * nla_ok - check if the netlink attribute fits into the remaining bytes
 * @nla: netlink attribute
 * @remaining: number of bytes remaining in attribute stream
 */
static inline int nla_ok(const struct nlattr *nla, int remaining)
{
      return remaining >= sizeof(*nla) &&
             nla->nla_len >= sizeof(*nla) &&
             nla->nla_len <= remaining;
}

/**
 * nla_next - next netlink attribute in attribute stream
 * @nla: netlink attribute
 * @remaining: number of bytes remaining in attribute stream
 *
 * Returns the next netlink attribute in the attribute stream and
 * decrements remaining by the size of the current attribute.
 */
static inline struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
{
      int totlen = NLA_ALIGN(nla->nla_len);

      *remaining -= totlen;
      return (struct nlattr *) ((char *) nla + totlen);
}

/**
 * nla_find_nested - find attribute in a set of nested attributes
 * @nla: attribute containing the nested attributes
 * @attrtype: type of attribute to look for
 *
 * Returns the first attribute which matches the specified type.
 */
static inline struct nlattr *nla_find_nested(struct nlattr *nla, int attrtype)
{
      return nla_find(nla_data(nla), nla_len(nla), attrtype);
}

/**
 * nla_parse_nested - parse nested attributes
 * @tb: destination array with maxtype+1 elements
 * @maxtype: maximum attribute type to be expected
 * @nla: attribute containing the nested attributes
 * @policy: validation policy
 *
 * See nla_parse()
 */
static inline int nla_parse_nested(struct nlattr *tb[], int maxtype,
                           struct nlattr *nla,
                           const struct nla_policy *policy)
{
      return nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy);
}

/**
 * nla_parse_nested_compat - parse nested compat attributes
 * @tb: destination array with maxtype+1 elements
 * @maxtype: maximum attribute type to be expected
 * @nla: attribute containing the nested attributes
 * @data: pointer to point to contained structure
 * @len: length of contained structure
 * @policy: validation policy
 *
 * Parse a nested compat attribute. The compat attribute contains a structure
 * and optionally a set of nested attributes. On success the data pointer
 * points to the nested data and tb contains the parsed attributes
 * (see nla_parse).
 */
static inline int __nla_parse_nested_compat(struct nlattr *tb[], int maxtype,
                                  struct nlattr *nla,
                                  const struct nla_policy *policy,
                                  int len)
{
      if (nla_len(nla) < len)
            return -1;
      if (nla_len(nla) >= NLA_ALIGN(len) + sizeof(struct nlattr))
            return nla_parse_nested(tb, maxtype,
                              nla_data(nla) + NLA_ALIGN(len),
                              policy);
      memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
      return 0;
}

#define nla_parse_nested_compat(tb, maxtype, nla, policy, data, len) \
({    data = nla_len(nla) >= len ? nla_data(nla) : NULL; \
      __nla_parse_nested_compat(tb, maxtype, nla, policy, len); })
/**
 * nla_put_u8 - Add a u8 netlink attribute to a socket buffer
 * @skb: socket buffer to add attribute to
 * @attrtype: attribute type
 * @value: numeric value
 */
static inline int nla_put_u8(struct sk_buff *skb, int attrtype, u8 value)
{
      return nla_put(skb, attrtype, sizeof(u8), &value);
}

/**
 * nla_put_u16 - Add a u16 netlink attribute to a socket buffer
 * @skb: socket buffer to add attribute to
 * @attrtype: attribute type
 * @value: numeric value
 */
static inline int nla_put_u16(struct sk_buff *skb, int attrtype, u16 value)
{
      return nla_put(skb, attrtype, sizeof(u16), &value);
}

/**
 * nla_put_u32 - Add a u32 netlink attribute to a socket buffer
 * @skb: socket buffer to add attribute to
 * @attrtype: attribute type
 * @value: numeric value
 */
static inline int nla_put_u32(struct sk_buff *skb, int attrtype, u32 value)
{
      return nla_put(skb, attrtype, sizeof(u32), &value);
}

/**
 * nla_put_64 - Add a u64 netlink attribute to a socket buffer
 * @skb: socket buffer to add attribute to
 * @attrtype: attribute type
 * @value: numeric value
 */
static inline int nla_put_u64(struct sk_buff *skb, int attrtype, u64 value)
{
      return nla_put(skb, attrtype, sizeof(u64), &value);
}

/**
 * nla_put_string - Add a string netlink attribute to a socket buffer
 * @skb: socket buffer to add attribute to
 * @attrtype: attribute type
 * @str: NUL terminated string
 */
static inline int nla_put_string(struct sk_buff *skb, int attrtype,
                         const char *str)
{
      return nla_put(skb, attrtype, strlen(str) + 1, str);
}

/**
 * nla_put_flag - Add a flag netlink attribute to a socket buffer
 * @skb: socket buffer to add attribute to
 * @attrtype: attribute type
 */
static inline int nla_put_flag(struct sk_buff *skb, int attrtype)
{
      return nla_put(skb, attrtype, 0, NULL);
}

/**
 * nla_put_msecs - Add a msecs netlink attribute to a socket buffer
 * @skb: socket buffer to add attribute to
 * @attrtype: attribute type
 * @jiffies: number of msecs in jiffies
 */
static inline int nla_put_msecs(struct sk_buff *skb, int attrtype,
                        unsigned long jiffies)
{
      u64 tmp = jiffies_to_msecs(jiffies);
      return nla_put(skb, attrtype, sizeof(u64), &tmp);
}

#define NLA_PUT(skb, attrtype, attrlen, data) \
      do { \
            if (nla_put(skb, attrtype, attrlen, data) < 0) \
                  goto nla_put_failure; \
      } while(0)

#define NLA_PUT_TYPE(skb, type, attrtype, value) \
      do { \
            type __tmp = value; \
            NLA_PUT(skb, attrtype, sizeof(type), &__tmp); \
      } while(0)

#define NLA_PUT_U8(skb, attrtype, value) \
      NLA_PUT_TYPE(skb, u8, attrtype, value)

#define NLA_PUT_U16(skb, attrtype, value) \
      NLA_PUT_TYPE(skb, u16, attrtype, value)

#define NLA_PUT_LE16(skb, attrtype, value) \
      NLA_PUT_TYPE(skb, __le16, attrtype, value)

#define NLA_PUT_U32(skb, attrtype, value) \
      NLA_PUT_TYPE(skb, u32, attrtype, value)

#define NLA_PUT_BE32(skb, attrtype, value) \
      NLA_PUT_TYPE(skb, __be32, attrtype, value)

#define NLA_PUT_U64(skb, attrtype, value) \
      NLA_PUT_TYPE(skb, u64, attrtype, value)

#define NLA_PUT_STRING(skb, attrtype, value) \
      NLA_PUT(skb, attrtype, strlen(value) + 1, value)

#define NLA_PUT_FLAG(skb, attrtype) \
      NLA_PUT(skb, attrtype, 0, NULL)

#define NLA_PUT_MSECS(skb, attrtype, jiffies) \
      NLA_PUT_U64(skb, attrtype, jiffies_to_msecs(jiffies))

/**
 * nla_get_u32 - return payload of u32 attribute
 * @nla: u32 netlink attribute
 */
static inline u32 nla_get_u32(struct nlattr *nla)
{
      return *(u32 *) nla_data(nla);
}

/**
 * nla_get_be32 - return payload of __be32 attribute
 * @nla: __be32 netlink attribute
 */
static inline __be32 nla_get_be32(struct nlattr *nla)
{
      return *(__be32 *) nla_data(nla);
}

/**
 * nla_get_u16 - return payload of u16 attribute
 * @nla: u16 netlink attribute
 */
static inline u16 nla_get_u16(struct nlattr *nla)
{
      return *(u16 *) nla_data(nla);
}

/**
 * nla_get_le16 - return payload of __le16 attribute
 * @nla: __le16 netlink attribute
 */
static inline __le16 nla_get_le16(struct nlattr *nla)
{
      return *(__le16 *) nla_data(nla);
}

/**
 * nla_get_u8 - return payload of u8 attribute
 * @nla: u8 netlink attribute
 */
static inline u8 nla_get_u8(struct nlattr *nla)
{
      return *(u8 *) nla_data(nla);
}

/**
 * nla_get_u64 - return payload of u64 attribute
 * @nla: u64 netlink attribute
 */
static inline u64 nla_get_u64(struct nlattr *nla)
{
      u64 tmp;

      nla_memcpy(&tmp, nla, sizeof(tmp));

      return tmp;
}

/**
 * nla_get_flag - return payload of flag attribute
 * @nla: flag netlink attribute
 */
static inline int nla_get_flag(struct nlattr *nla)
{
      return !!nla;
}

/**
 * nla_get_msecs - return payload of msecs attribute
 * @nla: msecs netlink attribute
 *
 * Returns the number of milliseconds in jiffies.
 */
static inline unsigned long nla_get_msecs(struct nlattr *nla)
{
      u64 msecs = nla_get_u64(nla);

      return msecs_to_jiffies((unsigned long) msecs);
}

/**
 * nla_nest_start - Start a new level of nested attributes
 * @skb: socket buffer to add attributes to
 * @attrtype: attribute type of container
 *
 * Returns the container attribute
 */
static inline struct nlattr *nla_nest_start(struct sk_buff *skb, int attrtype)
{
      struct nlattr *start = (struct nlattr *)skb_tail_pointer(skb);

      if (nla_put(skb, attrtype, 0, NULL) < 0)
            return NULL;

      return start;
}

/**
 * nla_nest_end - Finalize nesting of attributes
 * @skb: socket buffer the attributes are stored in
 * @start: container attribute
 *
 * Corrects the container attribute header to include the all
 * appeneded attributes.
 *
 * Returns the total data length of the skb.
 */
static inline int nla_nest_end(struct sk_buff *skb, struct nlattr *start)
{
      start->nla_len = skb_tail_pointer(skb) - (unsigned char *)start;
      return skb->len;
}

/**
 * nla_nest_compat_start - Start a new level of nested compat attributes
 * @skb: socket buffer to add attributes to
 * @attrtype: attribute type of container
 * @attrlen: length of structure
 * @data: pointer to structure
 *
 * Start a nested compat attribute that contains both a structure and
 * a set of nested attributes.
 *
 * Returns the container attribute
 */
static inline struct nlattr *nla_nest_compat_start(struct sk_buff *skb,
                                       int attrtype, int attrlen,
                                       const void *data)
{
      struct nlattr *start = (struct nlattr *)skb_tail_pointer(skb);

      if (nla_put(skb, attrtype, attrlen, data) < 0)
            return NULL;
      if (nla_nest_start(skb, attrtype) == NULL) {
            nlmsg_trim(skb, start);
            return NULL;
      }
      return start;
}

/**
 * nla_nest_compat_end - Finalize nesting of compat attributes
 * @skb: socket buffer the attributes are stored in
 * @start: container attribute
 *
 * Corrects the container attribute header to include the all
 * appeneded attributes.
 *
 * Returns the total data length of the skb.
 */
static inline int nla_nest_compat_end(struct sk_buff *skb, struct nlattr *start)
{
      struct nlattr *nest = (void *)start + NLMSG_ALIGN(start->nla_len);

      start->nla_len = skb_tail_pointer(skb) - (unsigned char *)start;
      return nla_nest_end(skb, nest);
}

/**
 * nla_nest_cancel - Cancel nesting of attributes
 * @skb: socket buffer the message is stored in
 * @start: container attribute
 *
 * Removes the container attribute and including all nested
 * attributes. Returns -1.
 */
static inline int nla_nest_cancel(struct sk_buff *skb, struct nlattr *start)
{
      return nlmsg_trim(skb, start);
}

/**
 * nla_validate_nested - Validate a stream of nested attributes
 * @start: container attribute
 * @maxtype: maximum attribute type to be expected
 * @policy: validation policy
 *
 * Validates all attributes in the nested attribute stream against the
 * specified policy. Attributes with a type exceeding maxtype will be
 * ignored. See documenation of struct nla_policy for more details.
 *
 * Returns 0 on success or a negative error code.
 */
static inline int nla_validate_nested(struct nlattr *start, int maxtype,
                              const struct nla_policy *policy)
{
      return nla_validate(nla_data(start), nla_len(start), maxtype, policy);
}

/**
 * nla_for_each_attr - iterate over a stream of attributes
 * @pos: loop counter, set to current attribute
 * @head: head of attribute stream
 * @len: length of attribute stream
 * @rem: initialized to len, holds bytes currently remaining in stream
 */
#define nla_for_each_attr(pos, head, len, rem) \
      for (pos = head, rem = len; \
           nla_ok(pos, rem); \
           pos = nla_next(pos, &(rem)))

/**
 * nla_for_each_nested - iterate over nested attributes
 * @pos: loop counter, set to current attribute
 * @nla: attribute containing the nested attributes
 * @rem: initialized to len, holds bytes currently remaining in stream
 */
#define nla_for_each_nested(pos, nla, rem) \
      nla_for_each_attr(pos, nla_data(nla), nla_len(nla), rem)

#endif

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