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Diffstat (limited to 'package/libs/libnl-tiny/src/msg.c')
| -rw-r--r-- | package/libs/libnl-tiny/src/msg.c | 566 |
1 files changed, 566 insertions, 0 deletions
diff --git a/package/libs/libnl-tiny/src/msg.c b/package/libs/libnl-tiny/src/msg.c new file mode 100644 index 0000000..e84c281 --- /dev/null +++ b/package/libs/libnl-tiny/src/msg.c @@ -0,0 +1,566 @@ +/* + * 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); +} + +/** @} */ |