+/*
+ * lib/attr.c Netlink Attributes
+ *
+ * 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>
+ */
+
+#include <netlink-local.h>
+#include <netlink/netlink.h>
+#include <netlink/utils.h>
+#include <netlink/addr.h>
+#include <netlink/attr.h>
+#include <netlink/msg.h>
+#include <linux/socket.h>
+
+/**
+ * @ingroup nl
+ * @defgroup attr Attributes
+ * Netlink Attributes Construction/Parsing Interface
+ * @par 0) Introduction
+ * Netlink attributes are chained together following each other:
+ * @code
+ * <------- nla_total_size(payload) ------->
+ * <---- nla_attr_size(payload) ----->
+ * +----------+- - -+- - - - - - - - - +- - -+-------- - -
+ * | Header | Pad | Payload | Pad | Header
+ * +----------+- - -+- - - - - - - - - +- - -+-------- - -
+ * <- nla_len(nla) -> ^
+ * nla_data(nla)----^ |
+ * nla_next(nla)-----------------------------'
+ * @endcode
+ *
+ * @par
+ * The attribute header and payload must be aligned properly:
+ * @code
+ * <------- NLA_HDRLEN ------> <-- NLA_ALIGN(payload)-->
+ * +---------------------+- - -+- - - - - - - - - -+- - -+
+ * | Header | Pad | Payload | Pad |
+ * | (struct nlattr) | ing | | ing |
+ * +---------------------+- - -+- - - - - - - - - -+- - -+
+ * <-------------- nlattr->nla_len -------------->
+ * @endcode
+ *
+ * @par Nested TLVs:
+ * Nested TLVs are an array of TLVs nested into another TLV. This can be useful
+ * to allow subsystems to have their own formatting rules without the need to
+ * make the underlying layer be aware of it. It can also be useful to transfer
+ * arrays, lists and flattened trees.
+ * \code
+ * <-------------------- NLA_ALIGN(...) ------------------->
+ * +---------------+- - - - - - - - - - - - - - - - - -+- - -+
+ * | |+---------+---------+- - -+-------+| |
+ * | TLV Header || TLV 1 | TLV 2 | | TLV n || Pad |
+ * | |+---------+---------+- - -+-------+| |
+ * +---------------+- - - - - - - - - - - - - - - - - -+- - -+
+ * <--------- nla_data(nla) --------->
+ * \endcode
+ *
+ * @par 1) Constructing a message with attributes
+ * @code
+ * int param1 = 10;
+ * char *param2 = "parameter text";
+ * struct nlmsghdr hdr = {
+ * .nlmsg_type = MY_ACTION,
+ * };
+ * struct nl_msg *m = nlmsg_build(&hdr);
+ * nla_put_u32(m, 1, param1);
+ * nla_put_string(m, 2, param2);
+ *
+ * nl_send_auto_complete(handle, nl_msg_get(m));
+ * nlmsg_free(m);
+ * @endcode
+ *
+ * @par 2) Constructing nested attributes
+ * @code
+ * struct nl_msg * nested_config(void)
+ * {
+ * int a = 5, int b = 10;
+ * struct nl_msg *n = nlmsg_build(NULL);
+ * nla_put_u32(n, 10, a);
+ * nla_put_u32(n, 20, b);
+ * return n;
+ * }
+ *
+ * ...
+ * struct nl_msg *m = nlmsg_build(&hdr);
+ * struct nl_msg *nest = nested_config();
+ * nla_put_nested(m, 1, nest);
+ *
+ * nl_send_auto_complete(handle, nl_msg_get(m));
+ * nlmsg_free(nest);
+ * nlmsg_free(m);
+ * @endcode
+ * @{
+ */
+
+/**
+ * @name Size Calculations
+ * @{
+ */
+
+/**
+ * length of attribute not including padding
+ * @arg payload length of payload
+ */
+int nla_attr_size(int payload)
+{
+ return NLA_HDRLEN + payload;
+}
+
+/**
+ * total length of attribute including padding
+ * @arg payload length of payload
+ */
+int nla_total_size(int payload)
+{
+ return NLA_ALIGN(nla_attr_size(payload));
+}
+
+/**
+ * length of padding at the tail of the attribute
+ * @arg payload length of payload
+ */
+int nla_padlen(int payload)
+{
+ return nla_total_size(payload) - nla_attr_size(payload);
+}
+
+/** @} */
+
+/**
+ * @name Payload Access
+ * @{
+ */
+
+/**
+ * head of payload
+ * @arg nla netlink attribute
+ */
+void *nla_data(const struct nlattr *nla)
+{
+ return (char *) nla + NLA_HDRLEN;
+}
+
+/**
+ * length of payload
+ * @arg nla netlink attribute
+ */
+int nla_len(const struct nlattr *nla)
+{
+ return nla->nla_len - NLA_HDRLEN;
+}
+
+/** @} */
+
+/**
+ * @name Attribute Parsing
+ * @{
+ */
+
+/**
+ * check if the netlink attribute fits into the remaining bytes
+ * @arg nla netlink attribute
+ * @arg remaining number of bytes remaining in attribute stream
+ */
+int nla_ok(const struct nlattr *nla, int remaining)
+{
+ return remaining >= sizeof(*nla) &&
+ nla->nla_len >= sizeof(*nla) &&
+ nla->nla_len <= remaining;
+}
+
+/**
+ * next netlink attribte in attribute stream
+ * @arg nla netlink attribute
+ * @arg remaining number of bytes remaining in attribute stream
+ *
+ * @return the next netlink attribute in the attribute stream and
+ * decrements remaining by the size of the current attribute.
+ */
+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 uint16_t nla_attr_minlen[NLA_TYPE_MAX+1] = {
+ [NLA_U8] = sizeof(uint8_t),
+ [NLA_U16] = sizeof(uint16_t),
+ [NLA_U32] = sizeof(uint32_t),
+ [NLA_U64] = sizeof(uint64_t),
+ [NLA_STRING] = 1,
+ [NLA_NESTED] = NLA_HDRLEN,
+};
+
+static int validate_nla(struct nlattr *nla, int maxtype,
+ struct nla_policy *policy)
+{
+ struct nla_policy *pt;
+ int minlen = 0;
+
+ if (nla->nla_type <= 0 || nla->nla_type > maxtype)
+ return 0;
+
+ pt = &policy[nla->nla_type];
+
+ if (pt->type > NLA_TYPE_MAX)
+ BUG();
+
+ if (pt->minlen)
+ minlen = pt->minlen;
+ else if (pt->type != NLA_UNSPEC)
+ minlen = nla_attr_minlen[pt->type];
+
+ if (pt->type == NLA_FLAG && nla_len(nla) > 0)
+ return -ERANGE;
+
+ if (nla_len(nla) < minlen)
+ return -ERANGE;
+
+ if (pt->maxlen && nla_len(nla) > pt->maxlen)
+ return -ERANGE;
+
+ if (pt->type == NLA_STRING) {
+ char *data = nla_data(nla);
+ if (data[nla_len(nla) - 1] != '\0')
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+
+/**
+ * Parse a stream of attributes into a tb buffer
+ * @arg tb destination array with maxtype+1 elements
+ * @arg maxtype maximum attribute type to be expected
+ * @arg head head of attribute stream
+ * @arg len length of attribute stream
+ * @arg policy validation policy
+ *
+ * Parses a stream of attributes and stores a pointer to each attribute in
+ * the tb array accessable via the attribute type. Attributes with a type
+ * exceeding maxtype will be silently ignored for backwards compatibility
+ * reasons. policy may be set to NULL if no validation is required.
+ *
+ * @return 0 on success or a negative error code.
+ */
+int nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head, int len,
+ struct nla_policy *policy)
+{
+ struct nlattr *nla;
+ int rem, err;
+
+ memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
+
+ nla_for_each_attr(nla, head, len, rem) {
+ uint16_t type = nla->nla_type;
+
+ if (type == 0) {
+ fprintf(stderr, "Illegal nla->nla_type == 0\n");
+ continue;
+ }
+
+ if (type <= maxtype) {
+ if (policy) {
+ err = validate_nla(nla, maxtype, policy);
+ if (err < 0)
+ goto errout;
+ }
+
+ tb[type] = nla;
+ }
+ }
+
+ if (rem > 0)
+ fprintf(stderr, "netlink: %d bytes leftover after parsing "
+ "attributes.\n", rem);
+
+ err = 0;
+errout:
+ return err;
+}
+
+
+/**
+ * parse nested attributes
+ * @arg tb destination array with maxtype+1 elements
+ * @arg maxtype maximum attribute type to be expected
+ * @arg nla attribute containing the nested attributes
+ * @arg policy validation policy
+ *
+ * @see nla_parse()
+ */
+int nla_parse_nested(struct nlattr *tb[], int maxtype, struct nlattr *nla,
+ struct nla_policy *policy)
+{
+ return nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy);
+}
+
+/**
+ * Validate a stream of attributes
+ * @arg head head of attribute stream
+ * @arg len length of attribute stream
+ * @arg maxtype maximum attribute type to be expected
+ * @arg policy validation policy
+ *
+ * Validates all attributes in the specified attribute stream
+ * against the specified policy. Attributes with a type exceeding
+ * maxtype will be ignored. See documenation of struct nla_policy
+ * for more details.
+ *
+ * @return 0 on success or a negative error code.
+ */
+int nla_validate(struct nlattr *head, int len, int maxtype,
+ struct nla_policy *policy)
+{
+ struct nlattr *nla;
+ int rem, err;
+
+ nla_for_each_attr(nla, head, len, rem) {
+ err = validate_nla(nla, maxtype, policy);
+ if (err < 0)
+ goto errout;
+ }
+
+ err = 0;
+errout:
+ return err;
+}
+
+/**
+ * Find a specific attribute in a stream of attributes
+ * @arg head head of attribute stream
+ * @arg len length of attribute stream
+ * @arg attrtype type of attribute to look for
+ *
+ * @return the first attribute in the stream matching the specified type.
+ */
+struct nlattr *nla_find(struct nlattr *head, int len, int attrtype)
+{
+ struct nlattr *nla;
+ int rem;
+
+ nla_for_each_attr(nla, head, len, rem)
+ if (nla->nla_type == attrtype)
+ return nla;
+
+ return NULL;
+}
+
+/** @} */
+
+/**
+ * @name Utilities
+ * @{
+ */
+
+/**
+ * Copy a netlink attribute into another memory area
+ * @arg dest where to copy to memcpy
+ * @arg src netlink attribute to copy from
+ * @arg count size of the destination area
+ *
+ * Note: The number of bytes copied is limited by the length of
+ * attribute's payload. memcpy
+ *
+ * @return the number of bytes copied.
+ */
+int nla_memcpy(void *dest, struct nlattr *src, int count)
+{
+ int minlen;
+
+ if (!src)
+ return 0;
+
+ minlen = min_t(int, count, nla_len(src));
+ memcpy(dest, nla_data(src), minlen);
+
+ return minlen;
+}
+
+/**
+ * Copy string attribute payload into a sized buffer
+ * @arg dst where to copy the string to
+ * @arg nla attribute to copy the string from
+ * @arg dstsize size of destination buffer
+ *
+ * Copies at most dstsize - 1 bytes into the destination buffer.
+ * The result is always a valid NUL-terminated string. Unlike
+ * strlcpy the destination buffer is always padded out.
+ *
+ * @return the length of the source buffer.
+ */
+size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
+{
+ size_t srclen = nla_len(nla);
+ char *src = nla_data(nla);
+
+ if (srclen > 0 && src[srclen - 1] == '\0')
+ srclen--;
+
+ if (dstsize > 0) {
+ size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
+
+ memset(dst, 0, dstsize);
+ memcpy(dst, src, len);
+ }
+
+ return srclen;
+}
+
+/**
+ * Compare an attribute with sized memory area
+ * @arg nla netlink attribute
+ * @arg data memory area
+ * @arg size size of memory area
+ */
+int nla_memcmp(const struct nlattr *nla, const void *data,
+ size_t size)
+{
+ int d = nla_len(nla) - size;
+
+ if (d == 0)
+ d = memcmp(nla_data(nla), data, size);
+
+ return d;
+}
+
+/**
+ * Compare a string attribute against a string
+ * @arg nla netlink string attribute
+ * @arg str another string
+ */
+int nla_strcmp(const struct nlattr *nla, const char *str)
+{
+ int len = strlen(str) + 1;
+ int d = nla_len(nla) - len;
+
+ if (d == 0)
+ d = memcmp(nla_data(nla), str, len);
+
+ return d;
+}
+
+/** @} */
+
+/**
+ * @name Attribute Construction
+ * @{
+ */
+
+/**
+ * reserve room for attribute on the skb
+ * @arg n netlink message
+ * @arg attrtype attribute type
+ * @arg attrlen length of attribute payload
+ *
+ * Adds a netlink attribute header to a netlink message and reserves
+ * room for the payload but does not copy it.
+ */
+struct nlattr *nla_reserve(struct nl_msg *n, int attrtype, int attrlen)
+{
+ struct nlattr *nla;
+ int tlen;
+
+ tlen = NLMSG_ALIGN(n->nm_nlh->nlmsg_len) + nla_total_size(attrlen);
+
+ n->nm_nlh = realloc(n->nm_nlh, tlen);
+ if (!n->nm_nlh) {
+ nl_errno(ENOMEM);
+ return NULL;
+ }
+
+ nla = (struct nlattr *) nlmsg_tail(n->nm_nlh);
+ nla->nla_type = attrtype;
+ nla->nla_len = nla_attr_size(attrlen);
+
+ memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
+ n->nm_nlh->nlmsg_len = tlen;
+
+ return nla;
+}
+
+/**
+ * Add a netlink attribute to a netlink message
+ * @arg n netlink message
+ * @arg attrtype attribute type
+ * @arg attrlen length of attribute payload
+ * @arg data head of attribute payload
+ *
+ * @return -1 if the tailroom of the skb is insufficient to store
+ * the attribute header and payload.
+ */
+int nla_put(struct nl_msg *n, int attrtype, int attrlen, const void *data)
+{
+ struct nlattr *nla;
+
+ nla = nla_reserve(n, attrtype, attrlen);
+ if (!nla)
+ return nl_errno(ENOMEM);
+
+ memcpy(nla_data(nla), data, attrlen);
+
+ return 0;
+}
+
+/**
+ * Add a nested netlink attribute to a netlink message
+ * @arg n netlink message
+ * @arg attrtype attribute type
+ * @arg nested netlink attribute to nest
+ *
+ * @return -1 if the tailroom of the skb is insufficient to store
+ * the attribute header and payload.
+ */
+int nla_put_nested(struct nl_msg *n, int attrtype, struct nl_msg *nested)
+{
+ return nla_put(n, attrtype, nlmsg_len(nested->nm_nlh),
+ nlmsg_data(nested->nm_nlh));
+}
+
+/**
+ * Add a u16 netlink attribute to a netlink message
+ * @arg n netlink message
+ * @arg attrtype attribute type
+ * @arg value numeric value
+ */
+int nla_put_u8(struct nl_msg *n, int attrtype, uint8_t value)
+{
+ return nla_put(n, attrtype, sizeof(uint8_t), &value);
+}
+
+/**
+ * Add a u16 netlink attribute to a netlink message
+ * @arg n netlink message
+ * @arg attrtype attribute type
+ * @arg value numeric value
+ */
+int nla_put_u16(struct nl_msg *n, int attrtype, uint16_t value)
+{
+ return nla_put(n, attrtype, sizeof(uint16_t), &value);
+}
+
+/**
+ * Add a u32 netlink attribute to a netlink message
+ * @arg n netlink message
+ * @arg attrtype attribute type
+ * @arg value numeric value
+ */
+int nla_put_u32(struct nl_msg *n, int attrtype, uint32_t value)
+{
+ return nla_put(n, attrtype, sizeof(uint32_t), &value);
+}
+
+/**
+ * Add a u64 netlink attribute to a netlink message
+ * @arg n netlink message
+ * @arg attrtype attribute type
+ * @arg value numeric value
+ */
+int nla_put_u64(struct nl_msg *n, int attrtype, uint64_t value)
+{
+ return nla_put(n, attrtype, sizeof(uint64_t), &value);
+}
+
+/**
+ * Add a string netlink attribute to a netlink message
+ * @arg n netlink message
+ * @arg attrtype attribute type
+ * @arg str NUL terminated string
+ */
+int nla_put_string(struct nl_msg *n, int attrtype, const char *str)
+{
+ return nla_put(n, attrtype, strlen(str) + 1, str);
+}
+
+/**
+ * Add a flag netlink attribute to a netlink message
+ * @arg n netlink message
+ * @arg attrtype attribute type
+ */
+int nla_put_flag(struct nl_msg *n, int attrtype)
+{
+ return nla_put(n, attrtype, 0, NULL);
+}
+
+/**
+ * Add a msecs netlink attribute to a netlink message
+ * @arg n netlink message
+ * @arg attrtype attribute type
+ * @arg msecs number of msecs
+ */
+int nla_put_msecs(struct nl_msg *n, int attrtype, unsigned long msecs)
+{
+ return nla_put_u64(n, attrtype, msecs);
+}
+
+/**
+ * Add an abstract data netlink attribute to a netlink message
+ * @arg n netlink message
+ * @arg attrtype attribute type
+ * @arg data abstract data
+ */
+int nla_put_data(struct nl_msg *n, int attrtype, struct nl_data *data)
+{
+ return nla_put(n, attrtype, nl_data_get_size(data),
+ nl_data_get(data));
+}
+
+/**
+ * Add an abstract address netlink attribute to a netlink message
+ * @arg n netlink message
+ * @arg attrtype attribute type
+ * @arg addr abstract address
+ */
+int nla_put_addr(struct nl_msg *n, int attrtype, struct nl_addr *addr)
+{
+ return nla_put(n, attrtype, nl_addr_get_len(addr),
+ nl_addr_get_binary_addr(addr));
+}
+
+/** @} */
+
+/**
+ * @name Attribute Nesting
+ * @{
+ */
+
+/**
+ * Start a new level of nested attributes
+ * @arg n netlink message
+ * @arg attrtype attribute type of container
+ *
+ * @return the container attribute
+ */
+struct nlattr *nla_nest_start(struct nl_msg *n, int attrtype)
+{
+ struct nlattr *start = (struct nlattr *) nlmsg_tail(n->nm_nlh);
+
+ if (nla_put(n, attrtype, 0, NULL) < 0)
+ return NULL;
+
+ return start;
+}
+
+/**
+ * Finalize nesting of attributes
+ * @arg n netlink message
+ * @arg start container attribute
+ *
+ * Corrects the container attribute header to include the all
+ * appeneded attributes.
+ *
+ * @return the total data length of the skb.
+ */
+int nla_nest_end(struct nl_msg *n, struct nlattr *start)
+{
+ start->nla_len = (unsigned char *) nlmsg_tail(n->nm_nlh) -
+ (unsigned char *) start;
+ return 0;
+}
+
+/** @} */
+
+/**
+ * @name Attribute Reading
+ * @{
+ */
+
+/**
+ * Return payload of u32 attribute
+ * @arg nla u32 netlink attribute
+ */
+uint32_t nla_get_u32(struct nlattr *nla)
+{
+ return *(uint32_t *) nla_data(nla);
+}
+
+/**
+ * Return payload of u16 attribute
+ * @arg nla u16 netlink attribute
+ */
+uint16_t nla_get_u16(struct nlattr *nla)
+{
+ return *(uint16_t *) nla_data(nla);
+}
+
+/**
+ * Return payload of u8 attribute
+ * @arg nla u8 netlink attribute
+ */
+uint8_t nla_get_u8(struct nlattr *nla)
+{
+ return *(uint8_t *) nla_data(nla);
+}
+
+/**
+ * Return payload of u64 attribute
+ * @arg nla u64 netlink attribute
+ */
+uint64_t nla_get_u64(struct nlattr *nla)
+{
+ uint64_t tmp;
+
+ nla_memcpy(&tmp, nla, sizeof(tmp));
+
+ return tmp;
+}
+
+/**
+ * Return payload of flag attribute
+ * @arg nla flag netlink attribute
+ */
+int nla_get_flag(struct nlattr *nla)
+{
+ return !!nla;
+}
+
+/**
+ * Return payload of msecs attribute
+ * @arg nla msecs netlink attribute
+ *
+ * @return the number of milliseconds.
+ */
+unsigned long nla_get_msecs(struct nlattr *nla)
+{
+ return nla_get_u64(nla);
+}
+
+/**
+ * Return payload of address attribute
+ * @arg nla address netlink attribute
+ * @arg family address family
+ *
+ * @return Newly allocated address handle or NULL
+ */
+struct nl_addr *nla_get_addr(struct nlattr *nla, int family)
+{
+ return nl_addr_build(family, nla_data(nla), nla_len(nla));
+}
+
+/**
+ * Return payload of abstract data attribute
+ * @arg nla abstract data netlink attribute
+ *
+ * @return Newly allocated abstract data handle or NULL
+ */
+struct nl_data *nla_get_data(struct nlattr *nla)
+{
+ return nl_data_alloc(nla_data(nla), nla_len(nla));
+}
+
+/** @} */
+
+/** @} */
git://git.onelab.eu / libnl.git / blobdiff