netlink.h

linux 内核源代码

		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
 *