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-/*
- * 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) 2003-2008 Thomas Graf <tgraf@suug.ch>
- */
-
-/**
- * @ingroup core
- * @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 <netlink/msg.h>
-#include <linux/socket.h>
-
-static size_t default_msg_size;
-
-static void __init init_msg_size(void)
-{
- default_msg_size = getpagesize();
-}
-
-/**
- * @name Attribute Access
- * @{
- */
-
-//** @} */
-
-/**
- * @name Message Parsing
- * @{
- */
-
-/**
- * check if the netlink message fits into the remaining bytes
- * @arg nlh netlink message header
- * @arg remaining number of bytes remaining in message stream
- */
-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.
- */
-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()
- */
-int nlmsg_parse(struct nlmsghdr *nlh, int hdrlen, struct nlattr *tb[],
- int maxtype, struct nla_policy *policy)
-{
- if (!nlmsg_valid_hdr(nlh, hdrlen))
- return -NLE_MSG_TOOSHORT;
-
- return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
- nlmsg_attrlen(nlh, hdrlen), policy);
-}
-
-/**
- * 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
- */
-int nlmsg_validate(struct nlmsghdr *nlh, int hdrlen, int maxtype,
- struct nla_policy *policy)
-{
- if (!nlmsg_valid_hdr(nlh, hdrlen))
- return -NLE_MSG_TOOSHORT;
-
- 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_refcnt = 1;
-
- nm->nm_nlh = malloc(len);
- if (!nm->nm_nlh)
- goto errout;
-
- memset(nm->nm_nlh, 0, sizeof(struct nlmsghdr));
-
- 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);
- 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.
- */
-struct nl_msg *nlmsg_alloc(void)
-{
- return __nlmsg_alloc(default_msg_size);
-}
-
-/**
- * Allocate a new netlink message with maximum payload size specified.
- */
-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
- */
-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.
- */
-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.
- */
-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.
- */
-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.
- */
-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)
- 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
- */
-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 -NLE_NOMEM;
-
- memcpy(tmp, data, len);
- NL_DBG(2, "msg %p: Appended %zu bytes with padding %d\n", n, len, pad);
-
- 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.
- */
-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;
-}
-
-/**
- * Release a reference from an netlink message
- * @arg msg message to release reference from
- *
- * Frees memory after the last reference has been released.
- */
-void nlmsg_free(struct nl_msg *msg)
-{
- if (!msg)
- return;
-
- msg->nm_refcnt--;
- NL_DBG(4, "Returned message reference %p, %d remaining\n",
- msg, msg->nm_refcnt);
-
- if (msg->nm_refcnt < 0)
- BUG();
-
- if (msg->nm_refcnt <= 0) {
- free(msg->nm_nlh);
- free(msg);
- NL_DBG(2, "msg %p: Freed\n", msg);
- }
-}
-
-/** @} */
-
-/**
- * @name Direct Parsing
- * @{
- */
-
-/** @cond SKIP */
-struct dp_xdata {
- void (*cb)(struct nl_object *, void *);
- void *arg;
-};
-/** @endcond */
-
-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 -NLE_MSGTYPE_NOSUPPORT;
- p.pp_arg = &x;
-
- return nl_cache_parse(ops, NULL, nlmsg_hdr(msg), &p);
-}
-
-/** @} */
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