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msg.c

/*
 * lib/msg.c            Netlink Messages Interface
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation version 2.1
 *    of the License.
 *
 * Copyright (c) 2003-2006 Thomas Graf <tgraf@suug.ch>
 */

/**
 * @ingroup nl
 * @defgroup msg Messages
 * Netlink Message Construction/Parsing Interface
 * 
 * The following information is partly extracted from RFC3549
 * (ftp://ftp.rfc-editor.org/in-notes/rfc3549.txt)
 *
 * @par Message Format
 * Netlink messages consist of a byte stream with one or multiple
 * Netlink headers and an associated payload.  If the payload is too big
 * to fit into a single message it, can be split over multiple Netlink
 * messages, collectively called a multipart message.  For multipart
 * messages, the first and all following headers have the \c NLM_F_MULTI
 * Netlink header flag set, except for the last header which has the
 * Netlink header type \c NLMSG_DONE.
 *
 * @par
 * The Netlink message header (\link nlmsghdr struct nlmsghdr\endlink) is shown below.
 * @code   
 * 0                   1                   2                   3
 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                          Length                             |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |            Type              |           Flags              |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                      Sequence Number                        |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                      Process ID (PID)                       |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * @endcode
 *
 * @par
 * The netlink message header and payload must be aligned properly:
 * @code
 *  <------- NLMSG_ALIGN(hlen) ------> <---- NLMSG_ALIGN(len) --->
 * +----------------------------+- - -+- - - - - - - - - - -+- - -+
 * |           Header           | Pad |       Payload       | Pad |
 * |      struct nlmsghdr       |     |                     |     |
 * +----------------------------+- - -+- - - - - - - - - - -+- - -+
 * @endcode
 * @par
 * Message Format:
 * @code
 *    <--- nlmsg_total_size(payload)  --->
 *    <-- nlmsg_msg_size(payload) ->
 *   +----------+- - -+-------------+- - -+-------- - -
 *   | nlmsghdr | Pad |   Payload   | Pad | nlmsghdr
 *   +----------+- - -+-------------+- - -+-------- - -
 *   nlmsg_data(nlh)---^                   ^
 *   nlmsg_next(nlh)-----------------------+
 * @endcode
 * @par
 * The payload may consist of arbitary data but may have strict
 * alignment and formatting rules depening on the specific netlink
 * families.
 * @par
 * @code
 *    <---------------------- nlmsg_len(nlh) --------------------->
 *    <------ hdrlen ------>       <- nlmsg_attrlen(nlh, hdrlen) ->
 *   +----------------------+- - -+--------------------------------+
 *   |     Family Header    | Pad |           Attributes           |
 *   +----------------------+- - -+--------------------------------+
 *   nlmsg_attrdata(nlh, hdrlen)---^
 * @endcode
 * @par The ACK Netlink Message
 * This message is actually used to denote both an ACK and a NACK.
 * Typically, the direction is from FEC to CPC (in response to an ACK
 * request message).  However, the CPC should be able to send ACKs back
 * to FEC when requested.
 * @code
 *  0                   1                   2                   3
 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                       Netlink message header                  |
 * |                       type = NLMSG_ERROR                      |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                          Error code                           |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                       OLD Netlink message header              |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * @endcode
 *
 * @par Example
 * @code
 * // Various methods exist to create/allocate a new netlink
 * // message. 
 * //
 * // nlmsg_alloc() will allocate an empty netlink message with
 * // a maximum payload size which defaults to the page size of
 * // the system. This default size can be modified using the
 * // function nlmsg_set_default_size().
 * struct nl_msg *msg = nlmsg_alloc();
 *
 * // Very often, the message type and message flags are known
 * // at allocation time while the other fields are auto generated:
 * struct nl_msg *msg = nlmsg_alloc_simple(MY_TYPE, MY_FLAGS);
 *
 * // Alternatively an existing netlink message header can be used
 * // to inherit the header values:
 * struct nlmsghdr hdr = {
 *    .nlmsg_type = MY_TYPE,
 *    .nlmsg_flags = MY_FLAGS,
 * };
 * struct nl_msg *msg = nlmsg_inherit(&hdr);
 *
 * // Last but not least, netlink messages received from netlink sockets
 * // can be converted into nl_msg objects using nlmsg_convert(). This
 * // will create a message with a maximum payload size which equals the
 * // length of the existing netlink message, therefore no more data can
 * // be appened without calling nlmsg_expand() first.
 * struct nl_msg *msg = nlmsg_convert(nlh_from_nl_sock);
 *
 * // Payload may be added to the message via nlmsg_append(). The fourth
 * // parameter specifies the number of alignment bytes the data should
 * // be padding with at the end. Common values are 0 to disable it or
 * // NLMSG_ALIGNTO to ensure proper netlink message padding.
 * nlmsg_append(msg, &mydata, sizeof(mydata), 0);
 *
 * // Sometimes it may be necessary to reserve room for data but defer
 * // the actual copying to a later point, nlmsg_reserve() can be used
 * // for this purpose:
 * void *data = nlmsg_reserve(msg, sizeof(mydata), NLMSG_ALIGNTO);
 *
 * // Attributes may be added using the attributes interface.
 *
 * // After successful use of the message, the memory must be freed
 * // using nlmsg_free()
 * nlmsg_free(msg);
 * @endcode
 * 
 * @par 4) Parsing messages
 * @code
 * int n;
 * unsigned char *buf;
 * struct nlmsghdr *hdr;
 *
 * n = nl_recv(handle, NULL, &buf);
 * 
 * hdr = (struct nlmsghdr *) buf;
 * while (nlmsg_ok(hdr, n)) {
 *    // Process message here...
 *    hdr = nlmsg_next(hdr, &n);
 * }
 * @endcode
 * @{
 */

#include <netlink-local.h>
#include <netlink/netlink.h>
#include <netlink/utils.h>
#include <netlink/cache.h>
#include <netlink/attr.h>
#include <linux/socket.h>

static size_t default_msg_size;

static void __init init_msg_size(void)
{
      default_msg_size = getpagesize();
}

/**
 * @name Size Calculations
 * @{
 */

/**
 * length of netlink message not including padding
 * @arg payload         length of message payload
 */
00184 int nlmsg_msg_size(int payload)
{
      return NLMSG_HDRLEN + payload;
}

/**
 * length of netlink message including padding
 * @arg payload         length of message payload
 */
00193 int nlmsg_total_size(int payload)
{
      return NLMSG_ALIGN(nlmsg_msg_size(payload));
}

/**
 * length of padding at the message's tail
 * @arg payload         length of message payload
 */
00202 int nlmsg_padlen(int payload)
{
      return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
}

/** @} */

/**
 * @name Payload Access
 * @{
 */

/**
 * head of message payload
 * @arg nlh       netlink messsage header
 */
00218 void *nlmsg_data(const struct nlmsghdr *nlh)
{
      return (unsigned char *) nlh + NLMSG_HDRLEN;
}

void *nlmsg_tail(const struct nlmsghdr *nlh)
{
      return (unsigned char *) nlh + NLMSG_ALIGN(nlh->nlmsg_len);
}

/**
 * length of message payload
 * @arg nlh       netlink message header
 */
00232 int nlmsg_len(const struct nlmsghdr *nlh)
{
      return nlh->nlmsg_len - NLMSG_HDRLEN;
}

/** @} */

/**
 * @name Attribute Access
 * @{
 */

/**
 * head of attributes data
 * @arg nlh       netlink message header
 * @arg hdrlen          length of family specific header
 */
00249 struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh, int hdrlen)
{
      unsigned char *data = nlmsg_data(nlh);
      return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
}

/**
 * length of attributes data
 * @arg nlh       netlink message header
 * @arg hdrlen          length of family specific header
 */
00260 int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
{
      return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
}

/** @} */

/**
 * @name Message Parsing
 * @{
 */

int nlmsg_valid_hdr(const struct nlmsghdr *nlh, int hdrlen)
{
      if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
            return 0;

      return 1;
}

/**
 * check if the netlink message fits into the remaining bytes
 * @arg nlh       netlink message header
 * @arg remaining number of bytes remaining in message stream
 */
00285 int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
{
      return (remaining >= sizeof(struct nlmsghdr) &&
            nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
            nlh->nlmsg_len <= remaining);
}

/**
 * next netlink message in message stream
 * @arg nlh       netlink message header
 * @arg 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.
 */
00300 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);
}

/**
 * parse attributes of a netlink message
 * @arg nlh       netlink message header
 * @arg hdrlen          length of family specific header
 * @arg tb        destination array with maxtype+1 elements
 * @arg maxtype         maximum attribute type to be expected
 * @arg policy          validation policy
 *
 * See nla_parse()
 */
00319 int nlmsg_parse(struct nlmsghdr *nlh, int hdrlen, struct nlattr *tb[],
            int maxtype, struct nla_policy *policy)
{
      if (!nlmsg_valid_hdr(nlh, hdrlen))
            return nl_errno(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
 * @arg nlh       netlink message header
 * @arg hdrlen          length of familiy specific header
 * @arg attrtype  type of attribute to look for
 *
 * Returns the first attribute which matches the specified type.
 */
00337 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
 * @arg nlh       netlinket message header
 * @arg hdrlen          length of familiy specific header
 * @arg maxtype         maximum attribute type to be expected
 * @arg policy          validation policy
 */
00350 int nlmsg_validate(struct nlmsghdr *nlh, int hdrlen, int maxtype,
               struct nla_policy *policy)
{
      if (!nlmsg_valid_hdr(nlh, hdrlen))
            return nl_errno(EINVAL);

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

/** @} */

/**
 * @name Message Building/Access
 * @{
 */

static struct nl_msg *__nlmsg_alloc(size_t len)
{
      struct nl_msg *nm;

      nm = calloc(1, sizeof(*nm));
      if (!nm)
            goto errout;

      nm->nm_nlh = calloc(1, len);
      if (!nm->nm_nlh)
            goto errout;

      nm->nm_protocol = -1;
      nm->nm_size = len;
      nm->nm_nlh->nlmsg_len = nlmsg_total_size(0);

      NL_DBG(2, "msg %p: Allocated new message, maxlen=%zu\n", nm, len);

      return nm;
errout:
      free(nm);
      nl_errno(ENOMEM);
      return NULL;
}

/**
 * Allocate a new netlink message with the default maximum payload size.
 *
 * Allocates a new netlink message without any further payload. The
 * maximum payload size defaults to PAGESIZE or as otherwise specified
 * with nlmsg_set_default_size().
 *
 * @return Newly allocated netlink message or NULL.
 */
00401 struct nl_msg *nlmsg_alloc(void)
{
      return __nlmsg_alloc(default_msg_size);
}

/**
 * Allocate a new netlink message with maximum payload size specified.
 */
00409 struct nl_msg *nlmsg_alloc_size(size_t max)
{
      return __nlmsg_alloc(max);
}

/**
 * Allocate a new netlink message and inherit netlink message header
 * @arg hdr       Netlink message header template
 *
 * Allocates a new netlink message and inherits the original message
 * header. If \a hdr is not NULL it will be used as a template for
 * the netlink message header, otherwise the header is left blank.
 * 
 * @return Newly allocated netlink message or NULL
 */ 
00424 struct nl_msg *nlmsg_inherit(struct nlmsghdr *hdr)
{
      struct nl_msg *nm;

      nm = nlmsg_alloc();
      if (nm && hdr) {
            struct nlmsghdr *new = nm->nm_nlh;

            new->nlmsg_type = hdr->nlmsg_type;
            new->nlmsg_flags = hdr->nlmsg_flags;
            new->nlmsg_seq = hdr->nlmsg_seq;
            new->nlmsg_pid = hdr->nlmsg_pid;
      }

      return nm;
}

/**
 * Allocate a new netlink message
 * @arg nlmsgtype Netlink message type
 * @arg flags           Message flags.
 *
 * @return Newly allocated netlink message or NULL.
 */
00448 struct nl_msg *nlmsg_alloc_simple(int nlmsgtype, int flags)
{
      struct nl_msg *msg;
      struct nlmsghdr nlh = {
            .nlmsg_type = nlmsgtype,
            .nlmsg_flags = flags,
      };

      msg = nlmsg_inherit(&nlh);
      if (msg)
            NL_DBG(2, "msg %p: Allocated new simple message\n", msg);

      return msg;
}

/**
 * Set the default maximum message payload size for allocated messages
 * @arg max       Size of payload in bytes.
 */
00467 void nlmsg_set_default_size(size_t max)
{
      if (max < nlmsg_total_size(0))
            max = nlmsg_total_size(0);

      default_msg_size = max;
}

/**
 * Convert a netlink message received from a netlink socket to a nl_msg
 * @arg hdr       Netlink message received from netlink socket.
 *
 * Allocates a new netlink message and copies all of the data pointed to
 * by \a hdr into the new message object.
 *
 * @return Newly allocated netlink message or NULL.
 */
00484 struct nl_msg *nlmsg_convert(struct nlmsghdr *hdr)
{
      struct nl_msg *nm;

      nm = __nlmsg_alloc(NLMSG_ALIGN(hdr->nlmsg_len));
      if (!nm)
            goto errout;

      memcpy(nm->nm_nlh, hdr, hdr->nlmsg_len);

      return nm;
errout:
      nlmsg_free(nm);
      return NULL;
}

/**
 * Reserve room for additional data in a netlink message
 * @arg n         netlink message
 * @arg len       length of additional data to reserve room for
 * @arg pad       number of bytes to align data to
 *
 * Reserves room for additional data at the tail of the an
 * existing netlink message. Eventual padding required will
 * be zeroed out.
 *
 * @return Pointer to start of additional data tailroom or NULL.
 */
00512 void *nlmsg_reserve(struct nl_msg *n, size_t len, int pad)
{
      void *buf = n->nm_nlh;
      size_t nlmsg_len = n->nm_nlh->nlmsg_len;
      size_t tlen;

      tlen = pad ? ((len + (pad - 1)) & ~(pad - 1)) : len;

      if ((tlen + nlmsg_len) > n->nm_size) {
            nl_errno(ENOBUFS);
            return NULL;
      }

      buf += nlmsg_len;
      n->nm_nlh->nlmsg_len += tlen;

      if (tlen > len)
            memset(buf + len, 0, tlen - len);

      NL_DBG(2, "msg %p: Reserved %zu bytes, pad=%d, nlmsg_len=%d\n",
              n, len, pad, n->nm_nlh->nlmsg_len);

      return buf;
}

/**
 * Append data to tail of a netlink message
 * @arg n         netlink message
 * @arg data            data to add
 * @arg len       length of data
 * @arg pad       Number of bytes to align data to.
 *
 * Extends the netlink message as needed and appends the data of given
 * length to the message. 
 *
 * @return 0 on success or a negative error code
 */
00549 int nlmsg_append(struct nl_msg *n, void *data, size_t len, int pad)
{
      void *tmp;

      tmp = nlmsg_reserve(n, len, pad);
      if (tmp == NULL)
            return nl_errno(ENOMEM);

      memcpy(tmp, data, len);
      NL_DBG(2, "msg %p: Appended %zu bytes with padding %d\n", n, len, pad);

      return 0;
}

/**
 * Expand maximum payload size of a netlink message
 * @arg n         Netlink message.
 * @arg newlen          New maximum payload size.
 *
 * Reallocates the payload section of a netlink message and increases
 * the maximum payload size of the message.
 *
 * @note Any pointers pointing to old payload block will be stale and
 *       need to be refetched. Therfore, do not expand while constructing
 *       nested attributes or while reserved data blocks are held.
 *
 * @return 0 on success or a negative error code.
 */
00577 int nlmsg_expand(struct nl_msg *n, size_t newlen)
{
      void *tmp;

      if (newlen <= n->nm_size)
            return nl_errno(EINVAL);

      tmp = realloc(n->nm_nlh, newlen);
      if (tmp == NULL)
            return nl_errno(ENOMEM);

      n->nm_nlh = tmp;
      n->nm_size = newlen;

      return 0;
}

/**
 * Add a netlink message header to a netlink message
 * @arg n         netlink message
 * @arg pid       netlink process id or NL_AUTO_PID
 * @arg seq       sequence number of message or NL_AUTO_SEQ
 * @arg type            message type
 * @arg payload         length of message payload
 * @arg flags           message flags
 *
 * Adds or overwrites the netlink message header in an existing message
 * object. If \a payload is greater-than zero additional room will be
 * reserved, f.e. for family specific headers. It can be accesed via
 * nlmsg_data().
 *
 * @return A pointer to the netlink message header or NULL.
 */
00610 struct nlmsghdr *nlmsg_put(struct nl_msg *n, uint32_t pid, uint32_t seq,
                     int type, int payload, int flags)
{
      struct nlmsghdr *nlh;

      if (n->nm_nlh->nlmsg_len < NLMSG_HDRLEN)
            BUG();

      nlh = (struct nlmsghdr *) n->nm_nlh;
      nlh->nlmsg_type = type;
      nlh->nlmsg_flags = flags;
      nlh->nlmsg_pid = pid;
      nlh->nlmsg_seq = seq;

      NL_DBG(2, "msg %p: Added netlink header type=%d, flags=%d, pid=%d, "
              "seq=%d\n", n, type, flags, pid, seq);

      if (payload > 0 &&
          nlmsg_reserve(n, payload, NLMSG_ALIGNTO) == NULL)
            return NULL;

      return nlh;
}

/**
 * Return actual netlink message
 * @arg n         netlink message
 * 
 * Returns the actual netlink message casted to the type of the netlink
 * message header.
 * 
 * @return A pointer to the netlink message.
 */
00643 struct nlmsghdr *nlmsg_hdr(struct nl_msg *n)
{
      return n->nm_nlh;
}

/**
 * Free a netlink message
 * @arg n         netlink message
 *
 * Destroys a netlink message and frees up all used memory.
 *
 * @pre The message must be unused.
 */
00656 void nlmsg_free(struct nl_msg *n)
{
      if (!n)
            return;

      free(n->nm_nlh);
      free(n);
      NL_DBG(2, "msg %p: Freed\n", n);
}

/** @} */

/**
 * @name Attributes
 * @{
 */

void nlmsg_set_proto(struct nl_msg *msg, int protocol)
{
      msg->nm_protocol = protocol;
}

int nlmsg_get_proto(struct nl_msg *msg)
{
      return msg->nm_protocol;
}

size_t nlmsg_get_max_size(struct nl_msg *msg)
{
      return msg->nm_size;
}

void nlmsg_set_src(struct nl_msg *msg, struct sockaddr_nl *addr)
{
      memcpy(&msg->nm_src, addr, sizeof(*addr));
}

struct sockaddr_nl *nlmsg_get_src(struct nl_msg *msg)
{
      return &msg->nm_src;
}

void nlmsg_set_dst(struct nl_msg *msg, struct sockaddr_nl *addr)
{
      memcpy(&msg->nm_dst, addr, sizeof(*addr));
}

struct sockaddr_nl *nlmsg_get_dst(struct nl_msg *msg)
{
      return &msg->nm_dst;
}

void nlmsg_set_creds(struct nl_msg *msg, struct ucred *creds)
{
      memcpy(&msg->nm_creds, creds, sizeof(*creds));
      msg->nm_flags |= NL_MSG_CRED_PRESENT;
}

struct ucred *nlmsg_get_creds(struct nl_msg *msg)
{
      if (msg->nm_flags & NL_MSG_CRED_PRESENT)
            return &msg->nm_creds;
      return NULL;
}

/** @} */

/**
 * @name Netlink Message Type Translations
 * @{
 */

static struct trans_tbl nl_msgtypes[] = {
      __ADD(NLMSG_NOOP,NOOP)
      __ADD(NLMSG_ERROR,ERROR)
      __ADD(NLMSG_DONE,DONE)
      __ADD(NLMSG_OVERRUN,OVERRUN)
};

char *nl_nlmsgtype2str(int type, char *buf, size_t size)
{
      return __type2str(type, buf, size, nl_msgtypes,
                    ARRAY_SIZE(nl_msgtypes));
}

int nl_str2nlmsgtype(const char *name)
{
      return __str2type(name, nl_msgtypes, ARRAY_SIZE(nl_msgtypes));
}

/** @} */

/**
 * @name Netlink Message Flags Translations
 * @{
 */

char *nl_nlmsg_flags2str(int flags, char *buf, size_t len)
{
      memset(buf, 0, len);

#define PRINT_FLAG(f) \
      if (flags & NLM_F_##f) { \
            flags &= ~NLM_F_##f; \
            strncat(buf, #f, len - strlen(buf) - 1); \
            if (flags) \
                  strncat(buf, ",", len - strlen(buf) - 1); \
      }
      
      PRINT_FLAG(REQUEST);
      PRINT_FLAG(MULTI);
      PRINT_FLAG(ACK);
      PRINT_FLAG(ECHO);
      PRINT_FLAG(ROOT);
      PRINT_FLAG(MATCH);
      PRINT_FLAG(ATOMIC);
      PRINT_FLAG(REPLACE);
      PRINT_FLAG(EXCL);
      PRINT_FLAG(CREATE);
      PRINT_FLAG(APPEND);

      if (flags) {
            char s[32];
            snprintf(s, sizeof(s), "0x%x", flags);
            strncat(buf, s, len - strlen(buf) - 1);
      }
#undef PRINT_FLAG

      return buf;
}

/** @} */

/**
 * @name Direct Parsing
 * @{
 */

/** @cond SKIP */
struct dp_xdata {
      void (*cb)(struct nl_object *, void *);
      void *arg;
};
/** @endcond */

00801 static int parse_cb(struct nl_object *obj, struct nl_parser_param *p)
{
      struct dp_xdata *x = p->pp_arg;

      x->cb(obj, x->arg);
      return 0;
}

int nl_msg_parse(struct nl_msg *msg, void (*cb)(struct nl_object *, void *),
             void *arg)
{
      struct nl_cache_ops *ops;
      struct nl_parser_param p = {
            .pp_cb = parse_cb
      };
      struct dp_xdata x = {
            .cb = cb,
            .arg = arg,
      };

      ops = nl_cache_ops_associate(nlmsg_get_proto(msg),
                             nlmsg_hdr(msg)->nlmsg_type);
      if (ops == NULL)
            return nl_error(ENOENT, "Unknown message type %d",
                        nlmsg_hdr(msg)->nlmsg_type);
      p.pp_arg = &x;

      return nl_cache_parse(ops, NULL, nlmsg_hdr(msg), &p);
}

/** @} */

/**
 * @name Dumping
 * @{
 */

static void prefix_line(FILE *ofd, int prefix)
{
      int i;

      for (i = 0; i < prefix; i++)
            fprintf(ofd, "  ");
}

static inline void dump_hex(FILE *ofd, char *start, int len, int prefix)
{
      int i, a, c, limit;
      char ascii[21] = {0};

      limit = 18 - (prefix * 2);
      prefix_line(ofd, prefix);
      fprintf(ofd, "    ");

      for (i = 0, a = 0, c = 0; i < len; i++) {
            int v = *(uint8_t *) (start + i);

            fprintf(ofd, "%02x ", v);
            ascii[a++] = isprint(v) ? v : '.';

            if (c == limit-1) {
                  fprintf(ofd, "%s\n", ascii);
                  if (i < (len - 1)) {
                        prefix_line(ofd, prefix);
                        fprintf(ofd, "    ");
                  }
                  a = c = 0;
                  memset(ascii, 0, sizeof(ascii));
            } else
                  c++;
      }

      if (c != 0) {
            for (i = 0; i < (limit - c); i++)
                  fprintf(ofd, "   ");
            fprintf(ofd, "%s\n", ascii);
      }
}

static void print_hdr(FILE *ofd, struct nl_msg *msg)
{
      struct nlmsghdr *nlh = nlmsg_hdr(msg);
      struct nl_cache_ops *ops;
      struct nl_msgtype *mt;
      char buf[128];

      fprintf(ofd, "    .nlmsg_len = %d\n", nlh->nlmsg_len);

      ops = nl_cache_ops_associate(nlmsg_get_proto(msg), nlh->nlmsg_type);
      if (ops) {
            mt = nl_msgtype_lookup(ops, nlh->nlmsg_type);
            if (!mt)
                  BUG();

            snprintf(buf, sizeof(buf), "%s::%s", ops->co_name, mt->mt_name);
      } else
            nl_nlmsgtype2str(nlh->nlmsg_type, buf, sizeof(buf));

      fprintf(ofd, "    .nlmsg_type = %d <%s>\n", nlh->nlmsg_type, buf);
      fprintf(ofd, "    .nlmsg_flags = %d <%s>\n", nlh->nlmsg_flags,
            nl_nlmsg_flags2str(nlh->nlmsg_flags, buf, sizeof(buf)));
      fprintf(ofd, "    .nlmsg_seq = %d\n", nlh->nlmsg_seq);
      fprintf(ofd, "    .nlmsg_pid = %d\n", nlh->nlmsg_pid);

}

static void dump_attrs(FILE *ofd, struct nlattr *attrs, int attrlen,
                   int prefix)
{
      int rem;
      struct nlattr *nla;

      nla_for_each_attr(nla, attrs, attrlen, rem) {
            int padlen, alen = nla_len(nla);

            prefix_line(ofd, prefix);
            fprintf(ofd, "  [ATTR %02d%s] %d octets\n", nla_type(nla),
                  nla->nla_type & NLA_F_NESTED ? " NESTED" : "",
                  alen);

            if (nla->nla_type & NLA_F_NESTED)
                  dump_attrs(ofd, nla_data(nla), alen, prefix+1);
            else
                  dump_hex(ofd, nla_data(nla), alen, prefix);

            padlen = nla_padlen(alen);
            if (padlen > 0) {
                  prefix_line(ofd, prefix);
                  fprintf(ofd, "  [PADDING] %d octets\n",
                        padlen);
                  dump_hex(ofd, nla_data(nla) + alen,
                         padlen, prefix);
            }
      }

      if (rem) {
            prefix_line(ofd, prefix);
            fprintf(ofd, "  [LEFTOVER] %d octets\n", rem);
      }
}

/**
 * Dump message in human readable format to file descriptor
 * @arg msg       Message to print
 * @arg ofd       File descriptor.
 */
00947 void nl_msg_dump(struct nl_msg *msg, FILE *ofd)
{
      struct nlmsghdr *hdr = nlmsg_hdr(msg);
      
      fprintf(ofd, 
      "--------------------------   BEGIN NETLINK MESSAGE "
      "---------------------------\n");

      fprintf(ofd, "  [HEADER] %Zu octets\n", sizeof(struct nlmsghdr));
      print_hdr(ofd, msg);

      if (hdr->nlmsg_type == NLMSG_ERROR &&
          hdr->nlmsg_len >= nlmsg_msg_size(sizeof(struct nlmsgerr))) {
            struct nl_msg *errmsg;
            struct nlmsgerr *err = nlmsg_data(hdr);

            fprintf(ofd, "  [ERRORMSG] %Zu octets\n", sizeof(*err));
            fprintf(ofd, "    .error = %d \"%s\"\n", err->error,
                  strerror(-err->error));
            fprintf(ofd, "  [ORIGINAL MESSAGE] %Zu octets\n", sizeof(*hdr));

            errmsg = nlmsg_inherit(&err->msg);
            print_hdr(ofd, errmsg);
            nlmsg_free(errmsg);
      } else if (nlmsg_len(hdr) > 0) {
            struct nl_cache_ops *ops;
            int payloadlen = nlmsg_len(hdr);
            int attrlen = 0;

            ops = nl_cache_ops_associate(nlmsg_get_proto(msg),
                                   hdr->nlmsg_type);
            if (ops) {
                  attrlen = nlmsg_attrlen(hdr, ops->co_hdrsize);
                  payloadlen -= attrlen;
            }

            fprintf(ofd, "  [PAYLOAD] %d octets\n", payloadlen);
            dump_hex(ofd, nlmsg_data(hdr), payloadlen, 0);

            if (attrlen) {
                  struct nlattr *attrs;
                  int attrlen;
                  
                  attrs = nlmsg_attrdata(hdr, ops->co_hdrsize);
                  attrlen = nlmsg_attrlen(hdr, ops->co_hdrsize);
                  dump_attrs(ofd, attrs, attrlen, 0);
            }
      }

      fprintf(ofd, 
      "---------------------------  END NETLINK MESSAGE   "
      "---------------------------\n");
}

/** @} */

/** @} */

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