diff options
Diffstat (limited to 'src/attr.c')
| -rw-r--r-- | src/attr.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/src/attr.c b/src/attr.c new file mode 100644 index 0000000..a724be0 --- /dev/null +++ b/src/attr.c @@ -0,0 +1,212 @@ +/* + * (C) 2008-2010 by Pablo Neira Ayuso <pablo@netfilter.org> + * + * This software may be used and distributed according to the terms + * of the GNU General Public License, incorporated herein by reference. + */ + +#include <libmnl/libmnl.h> +#include <string.h> + +/** + * Netlink attribute: + * + * |<-- 2 bytes -->|<-- 2 bytes -->|<-- variable -->| + * ------------------------------------------------- + * | length | type | value | + * ------------------------------------------------- + */ + +/** + * mnl_attr_get_type - get the attribute type of a netlink message + * + * This function returns the attribute type. + */ +u_int16_t mnl_attr_get_type(const struct nlattr *attr) +{ + return attr->nla_type & NLA_TYPE_MASK; +} + +/** + * mnl_attr_get_len - get the attribute length + * + * This function returns the attribute length. + */ +u_int16_t mnl_attr_get_len(const struct nlattr *attr) +{ + return attr->nla_len; +} + +/** + * mnl_attr_get_payload_len - get the attribute payload length + * + * This function returns the attribute payload length. + */ +u_int16_t mnl_attr_get_payload_len(const struct nlattr *attr) +{ + return attr->nla_len - MNL_ATTR_HDRLEN; +} + +/** + * mnl_attr_get_data - get pointer to the attribute payload + * + * This function return a pointer to the attribute payload + */ +void *mnl_attr_get_data(const struct nlattr *attr) +{ + return (void *)attr + MNL_ATTR_HDRLEN; +} + +/** + * mnl_attr_ok - check a there is room for an attribute + * @nlh: attribute that we want to check + * @len: remaining bytes in a buffer that contains the attribute + * + * This function is used to check that a buffer that contains an attribute + * has enough room for the attribute that it stores, ie. this function can + * be used to verify that an attribute is not malformed nor truncated. + */ +int mnl_attr_ok(const struct nlattr *attr, int len) +{ + return len >= sizeof(struct nlattr) && + attr->nla_len >= sizeof(struct nlattr) && + attr->nla_len <= len; +} + +/** + * mnl_attr_next - get the next attribute in the payload of a netlink message + * @attr: pointer to the current attribute + * @len: pointer to the current remaining bytes in the buffer + * + * This function returns a pointer to the next attribute that is in the + * payload of a netlink message. + */ +struct nlattr *mnl_attr_next(const struct nlattr *attr, int *len) +{ + *len -= mnl_align(attr->nla_len); + return (struct nlattr *)((void *)attr + mnl_align(attr->nla_len)); +} + +/** + * mnl_attr_parse - returns an array with the attributes in a message + * @tb: array of pointers to the attribute found + * @tb_size: size of the attribute array + * @attr: first attribute in the stream + * @len: remaining bytes in the buffer that contain attributes + * + * This function returns a table of pointers to the attributes that has been + * found in a netlink payload. This function return 0 on sucess, and >0 to + * indicate the number of bytes the remaining bytes. + */ +int mnl_attr_parse_at_offset(const struct nlmsghdr *nlh, int offset, + struct nlattr *tb[], int max) +{ + struct nlattr *attr = mnl_nlmsg_get_data_offset(nlh, offset); + int len = mnl_nlmsg_get_len(nlh); + + memset(tb, 0, sizeof(struct nlattr *) * (max + 1)); + + while (mnl_attr_ok(attr, len)) { + if (mnl_attr_get_type(attr) <= max) + tb[mnl_attr_get_type(attr)] = attr; + attr = mnl_attr_next(attr, &len); + } + return len; +} + +int mnl_attr_parse(const struct nlmsghdr *nlh, struct nlattr *tb[], int max) +{ + return mnl_attr_parse_at_offset(nlh, 0, tb, max); +} + +int mnl_attr_parse_nested(const struct nlattr *nested, + struct nlattr *tb[], int max) +{ + struct nlattr *attr = mnl_attr_get_data(nested); + int len = mnl_attr_get_payload_len(nested); + + memset(tb, 0, sizeof(struct nlattr *) * (max + 1)); + + while (mnl_attr_ok(attr, len)) { + if (mnl_attr_get_type(attr) <= max) + tb[mnl_attr_get_type(attr)] = attr; + attr = mnl_attr_next(attr, &len); + } + return len; +} + +u_int8_t mnl_attr_get_u8(const struct nlattr *attr) +{ + return *((u_int8_t *)mnl_attr_get_data(attr)); +} + +u_int16_t mnl_attr_get_u16(const struct nlattr *attr) +{ + return *((u_int16_t *)mnl_attr_get_data(attr)); +} + +u_int32_t mnl_attr_get_u32(const struct nlattr *attr) +{ + return *((u_int32_t *)mnl_attr_get_data(attr)); +} + +/** + * mnl_attr_get_u64 - returns an arra + * @attr: netlink attribute + * + * This function returns the payload of a 64-bits attribute. This function + * is align-safe since accessing 64-bits Netlink attributes is a common + * source of alignment issues. + */ +u_int64_t mnl_attr_get_u64(const struct nlattr *attr) +{ + u_int64_t tmp; + memcpy(&tmp, mnl_attr_get_data(attr), sizeof(tmp)); + return tmp; +} + +const char *mnl_attr_get_str(const struct nlattr *attr) +{ + return (const char *)mnl_attr_get_data(attr); +} + +void mnl_attr_put(struct nlmsghdr *nlh, int type, size_t len, const void *data) +{ + struct nlattr *attr = mnl_nlmsg_get_tail(nlh); + int payload_len = mnl_align(sizeof(struct nlattr)) + len; + + attr->nla_type = type; + attr->nla_len = payload_len; + memcpy(mnl_attr_get_data(attr), data, len); + nlh->nlmsg_len += mnl_align(payload_len); +} + +void mnl_attr_put_u8(struct nlmsghdr *nlh, int type, u_int8_t data) +{ + mnl_attr_put(nlh, type, sizeof(u_int8_t), &data); +} + +void mnl_attr_put_u16(struct nlmsghdr *nlh, int type, u_int16_t data) +{ + mnl_attr_put(nlh, type, sizeof(u_int16_t), &data); +} + +void mnl_attr_put_u32(struct nlmsghdr *nlh, int type, u_int32_t data) +{ + mnl_attr_put(nlh, type, sizeof(u_int32_t), &data); +} + +void mnl_attr_put_u64(struct nlmsghdr *nlh, int type, u_int64_t data) +{ + mnl_attr_put(nlh, type, sizeof(u_int64_t), &data); +} + +void mnl_attr_put_str(struct nlmsghdr *nlh, int type, const void *data) +{ + mnl_attr_put(nlh, type, strlen(data), data); +} + +void mnl_attr_put_str_null(struct nlmsghdr *nlh, int type, const void *data) +{ + mnl_attr_put(nlh, type, strlen(data)+1, data); +} |