netlink.h

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#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()            finalize 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
 *   nla_append(skb, len, data)     append data to skb
 *
 * 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_s8(skb, type, value)   add s8 attribute to skb
 *   nla_put_s16(skb, type, value)  add s16 attribute to skb
 *   nla_put_s32(skb, type, value)  add s32 attribute to skb
 *   nla_put_s64(skb, type, value)  add s64 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
 *
 * Nested Attributes Construction:
 *   nla_nest_start(skb, type)      start a nested attribute
 *   nla_nest_end(skb, nla)     finalize a nested 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_s8(nla)            get payload for a s8 attribute
 *   nla_get_s16(nla)           get payload for a s16 attribute
 *   nla_get_s32(nla)           get payload for a s32 attribute
 *   nla_get_s64(nla)           get payload for a s64 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_for_each_attr()        loop over all attributes
 *   nla_for_each_nested()      loop over the nested attributes
 *=========================================================================
 */

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_S8,
    NLA_S16,
    NLA_S32,
    NLA_S64,
    __NLA_TYPE_MAX,
};

#define NLA_TYPE_MAX (__NLA_TYPE_MAX - 1)

struct nla_policy {
    u16     type;
    u16     len;
};

struct nl_info {
    struct nlmsghdr     *nlh;
    struct net      *nl_net;
    u32         portid;
};

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 portid, unsigned int group, int report,
                     gfp_t flags);

extern int      nla_validate(const struct nlattr *head,
                     int len, int maxtype,
                     const struct nla_policy *policy);
extern int      nla_parse(struct nlattr **tb, int maxtype,
                  const struct nlattr *head, int len,
                  const struct nla_policy *policy);
extern int      nla_policy_len(const struct nla_policy *, int);
extern struct nlattr *  nla_find(const 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, const 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);
extern int      nla_append(struct sk_buff *skb, int attrlen,
                   const void *data);

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

static inline int nlmsg_msg_size(int payload)
{
    return NLMSG_HDRLEN + payload;
}

static inline int nlmsg_total_size(int payload)
{
    return NLMSG_ALIGN(nlmsg_msg_size(payload));
}

static inline int nlmsg_padlen(int payload)
{
    return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
}

static inline void *nlmsg_data(const struct nlmsghdr *nlh)
{
    return (unsigned char *) nlh + NLMSG_HDRLEN;
}

static inline int nlmsg_len(const struct nlmsghdr *nlh)
{
    return nlh->nlmsg_len - NLMSG_HDRLEN;
}

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));
}

static inline int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
{
    return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
}

static inline int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
{
    return (remaining >= (int) sizeof(struct nlmsghdr) &&
        nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
        nlh->nlmsg_len <= remaining);
}

static inline struct nlmsghdr *
nlmsg_next(const struct nlmsghdr *nlh, int *remaining)
{
    int totlen = NLMSG_ALIGN(nlh->nlmsg_len);

    *remaining -= totlen;

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

static inline int nlmsg_parse(const 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);
}

static inline struct nlattr *nlmsg_find_attr(const struct nlmsghdr *nlh,
                         int hdrlen, int attrtype)
{
    return nla_find(nlmsg_attrdata(nlh, hdrlen),
            nlmsg_attrlen(nlh, hdrlen), attrtype);
}

static inline int nlmsg_validate(const 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);
}

static inline int nlmsg_report(const struct nlmsghdr *nlh)
{
    return !!(nlh->nlmsg_flags & NLM_F_ECHO);
}

#define nlmsg_for_each_attr(pos, nlh, hdrlen, rem) \
    nla_for_each_attr(pos, nlmsg_attrdata(nlh, hdrlen), \
              nlmsg_attrlen(nlh, hdrlen), rem)

static inline struct nlmsghdr *nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
                     int type, int payload, int flags)
{
    if (unlikely(skb_tailroom(skb) < nlmsg_total_size(payload)))
        return NULL;

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

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).portid, cb->nlh->nlmsg_seq,
             type, payload, flags);
}

static inline struct sk_buff *nlmsg_new(size_t payload, gfp_t flags)
{
    return alloc_skb(nlmsg_total_size(payload), flags);
}

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;
}

static inline void *nlmsg_get_pos(struct sk_buff *skb)
{
    return skb_tail_pointer(skb);
}

static inline void nlmsg_trim(struct sk_buff *skb, const void *mark)
{
    if (mark)
        skb_trim(skb, (unsigned char *) mark - skb->data);
}

static inline void nlmsg_cancel(struct sk_buff *skb, struct nlmsghdr *nlh)
{
    nlmsg_trim(skb, nlh);
}

static inline void nlmsg_free(struct sk_buff *skb)
{
    kfree_skb(skb);
}

static inline int nlmsg_multicast(struct sock *sk, struct sk_buff *skb,
                  u32 portid, unsigned int group, gfp_t flags)
{
    int err;

    NETLINK_CB(skb).dst_group = group;

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

    return err;
}

static inline int nlmsg_unicast(struct sock *sk, struct sk_buff *skb, u32 portid)
{
    int err;

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

    return err;
}

#define nlmsg_for_each_msg(pos, head, len, rem) \
    for (pos = head, rem = len; \
         nlmsg_ok(pos, rem); \
         pos = nlmsg_next(pos, &(rem)))

static inline void
nl_dump_check_consistent(struct netlink_callback *cb,
             struct nlmsghdr *nlh)
{
    if (cb->prev_seq && cb->seq != cb->prev_seq)
        nlh->nlmsg_flags |= NLM_F_DUMP_INTR;
    cb->prev_seq = cb->seq;
}

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

static inline int nla_attr_size(int payload)
{
    return NLA_HDRLEN + payload;
}

static inline int nla_total_size(int payload)
{
    return NLA_ALIGN(nla_attr_size(payload));
}

static inline int nla_padlen(int payload)
{
    return nla_total_size(payload) - nla_attr_size(payload);
}

static inline int nla_type(const struct nlattr *nla)
{
    return nla->nla_type & NLA_TYPE_MASK;
}

static inline void *nla_data(const struct nlattr *nla)
{
    return (char *) nla + NLA_HDRLEN;
}

static inline int nla_len(const struct nlattr *nla)
{
    return nla->nla_len - NLA_HDRLEN;
}

static inline int nla_ok(const struct nlattr *nla, int remaining)
{
    return remaining >= (int) sizeof(*nla) &&
           nla->nla_len >= sizeof(*nla) &&
           nla->nla_len <= remaining;
}

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);
}

static inline struct nlattr *
nla_find_nested(const struct nlattr *nla, int attrtype)
{
    return nla_find(nla_data(nla), nla_len(nla), attrtype);
}

static inline int nla_parse_nested(struct nlattr *tb[], int maxtype,
                   const struct nlattr *nla,
                   const struct nla_policy *policy)
{
    return nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy);
}

static inline int nla_put_u8(struct sk_buff *skb, int attrtype, u8 value)
{
    return nla_put(skb, attrtype, sizeof(u8), &value);
}

static inline int nla_put_u16(struct sk_buff *skb, int attrtype, u16 value)
{
    return nla_put(skb, attrtype, sizeof(u16), &value);
}

static inline int nla_put_be16(struct sk_buff *skb, int attrtype, __be16 value)
{
    return nla_put(skb, attrtype, sizeof(__be16), &value);
}

static inline int nla_put_net16(struct sk_buff *skb, int attrtype, __be16 value)
{
    return nla_put_be16(skb, attrtype | NLA_F_NET_BYTEORDER, value);
}

static inline int nla_put_le16(struct sk_buff *skb, int attrtype, __le16 value)
{
    return nla_put(skb, attrtype, sizeof(__le16), &value);
}

static inline int nla_put_u32(struct sk_buff *skb, int attrtype, u32 value)
{
    return nla_put(skb, attrtype, sizeof(u32), &value);
}

static inline int nla_put_be32(struct sk_buff *skb, int attrtype, __be32 value)
{
    return nla_put(skb, attrtype, sizeof(__be32), &value);
}

static inline int nla_put_net32(struct sk_buff *skb, int attrtype, __be32 value)
{
    return nla_put_be32(skb, attrtype | NLA_F_NET_BYTEORDER, value);
}

static inline int nla_put_le32(struct sk_buff *skb, int attrtype, __le32 value)
{
    return nla_put(skb, attrtype, sizeof(__le32), &value);
}

static inline int nla_put_u64(struct sk_buff *skb, int attrtype, u64 value)
{
    return nla_put(skb, attrtype, sizeof(u64), &value);
}

static inline int nla_put_be64(struct sk_buff *skb, int attrtype, __be64 value)
{
    return nla_put(skb, attrtype, sizeof(__be64), &value);
}

static inline int nla_put_net64(struct sk_buff *skb, int attrtype, __be64 value)
{
    return nla_put_be64(skb, attrtype | NLA_F_NET_BYTEORDER, value);
}

static inline int nla_put_le64(struct sk_buff *skb, int attrtype, __le64 value)
{
    return nla_put(skb, attrtype, sizeof(__le64), &value);
}

static inline int nla_put_s8(struct sk_buff *skb, int attrtype, s8 value)
{
    return nla_put(skb, attrtype, sizeof(s8), &value);
}

static inline int nla_put_s16(struct sk_buff *skb, int attrtype, s16 value)
{
    return nla_put(skb, attrtype, sizeof(s16), &value);
}

static inline int nla_put_s32(struct sk_buff *skb, int attrtype, s32 value)
{
    return nla_put(skb, attrtype, sizeof(s32), &value);
}

static inline int nla_put_s64(struct sk_buff *skb, int attrtype, s64 value)
{
    return nla_put(skb, attrtype, sizeof(s64), &value);
}

static inline int nla_put_string(struct sk_buff *skb, int attrtype,
                 const char *str)
{
    return nla_put(skb, attrtype, strlen(str) + 1, str);
}

static inline int nla_put_flag(struct sk_buff *skb, int attrtype)
{
    return nla_put(skb, attrtype, 0, NULL);
}

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);
}

static inline u32 nla_get_u32(const struct nlattr *nla)
{
    return *(u32 *) nla_data(nla);
}

static inline __be32 nla_get_be32(const struct nlattr *nla)
{
    return *(__be32 *) nla_data(nla);
}

static inline u16 nla_get_u16(const struct nlattr *nla)
{
    return *(u16 *) nla_data(nla);
}

static inline __be16 nla_get_be16(const struct nlattr *nla)
{
    return *(__be16 *) nla_data(nla);
}

static inline __le16 nla_get_le16(const struct nlattr *nla)
{
    return *(__le16 *) nla_data(nla);
}

static inline u8 nla_get_u8(const struct nlattr *nla)
{
    return *(u8 *) nla_data(nla);
}

static inline u64 nla_get_u64(const struct nlattr *nla)
{
    u64 tmp;

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

    return tmp;
}

static inline __be64 nla_get_be64(const struct nlattr *nla)
{
    __be64 tmp;

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

    return tmp;
}

static inline s32 nla_get_s32(const struct nlattr *nla)
{
    return *(s32 *) nla_data(nla);
}

static inline s16 nla_get_s16(const struct nlattr *nla)
{
    return *(s16 *) nla_data(nla);
}

static inline s8 nla_get_s8(const struct nlattr *nla)
{
    return *(s8 *) nla_data(nla);
}

static inline s64 nla_get_s64(const struct nlattr *nla)
{
    s64 tmp;

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

    return tmp;
}

static inline int nla_get_flag(const struct nlattr *nla)
{
    return !!nla;
}

static inline unsigned long nla_get_msecs(const struct nlattr *nla)
{
    u64 msecs = nla_get_u64(nla);

    return msecs_to_jiffies((unsigned long) msecs);
}

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;
}

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;
}

static inline void nla_nest_cancel(struct sk_buff *skb, struct nlattr *start)
{
    nlmsg_trim(skb, start);
}

static inline int nla_validate_nested(const struct nlattr *start, int maxtype,
                      const struct nla_policy *policy)
{
    return nla_validate(nla_data(start), nla_len(start), maxtype, policy);
}

#define nla_for_each_attr(pos, head, len, rem) \
    for (pos = head, rem = len; \
         nla_ok(pos, rem); \
         pos = nla_next(pos, &(rem)))

#define nla_for_each_nested(pos, nla, rem) \
    nla_for_each_attr(pos, nla_data(nla), nla_len(nla), rem)

#endif