These functions allow to create a buffer (nftnl_attrbuf) of TLV objects (nftnl_attr). It is inspired by libmnl/src/attr.c. It can be used to store several variable length user data into an object.
Example usage: ``` struct nftnl_attrbuf *attrbuf; struct nftnl_attr *attr; const char str[] = "Hello World!"; attrbuf = nftnl_attrbuf_alloc(ATTRBUF_SIZE); if (!nftnl_attr_put_check(attrbuf, NFTNL_ATTR_TYPE_COMMENT, strlen(str), str) ) { fprintf(stderr, "Can't put attribute \"%s\"", str); } nftnl_attr_for_each(attr, attrbuf) { printf("%s\n", (char *)nftnl_attr_get_value(attr)); } nftnl_attr_free(attrbuf); ``` Signed-off-by: Carlos Falgueras García <carlo...@riseup.net> --- include/Makefile.am | 1 + include/attr.h | 40 +++++++++++++ include/libnftnl/Makefile.am | 1 + include/libnftnl/attr.h | 59 +++++++++++++++++++ src/Makefile.am | 1 + src/attr.c | 132 +++++++++++++++++++++++++++++++++++++++++++ src/libnftnl.map | 16 ++++++ 7 files changed, 250 insertions(+) create mode 100644 include/attr.h create mode 100644 include/libnftnl/attr.h create mode 100644 src/attr.c diff --git a/include/Makefile.am b/include/Makefile.am index be9eb9b..785ec15 100644 --- a/include/Makefile.am +++ b/include/Makefile.am @@ -12,4 +12,5 @@ noinst_HEADERS = internal.h \ expr.h \ json.h \ set_elem.h \ + attr.h \ utils.h diff --git a/include/attr.h b/include/attr.h new file mode 100644 index 0000000..2a29fa0 --- /dev/null +++ b/include/attr.h @@ -0,0 +1,40 @@ +#ifndef _LIBNFTNL_ATTR_INTERNAL_H_ +#define _LIBNFTNL_ATTR_INTERNAL_H_ + +#include <stdint.h> +#include <stddef.h> + +/* + * TLV structures: + * nftnl_attr + * <-------- HEADER --------> <------ PAYLOAD ------> + * +------------+-------------+- - - - - - - - - - - -+ + * | type | len | value | + * | (1 byte) | (1 byte) | | + * +--------------------------+- - - - - - - - - - - -+ + * <-- sizeof(nftnl_attr) --> <-- nftnl_attr->len --> + */ +struct __attribute__((__packed__)) nftnl_attr { + uint8_t type; + uint8_t len; + unsigned char value[]; +}; + +/* + * +-------------------------------------------++ + * | data[] || + * | || || + * | \/ \/ + * +-------+-------+- - - - -+-------+-------+ ... +-------+- - - - - - -+ + * | size | end | padding | TLV | TLV | | TLV | Empty | + * +-------+-------+- - - - -+-------+-------+ ... +-------+- - - - - - -+ + * |<- nftnl_attrbuf_get_len() ->| + * |<-------- nftnl_attrbuf_get_size() ------->| + */ +struct nftnl_attrbuf { + size_t size; + char *end; + char data[] __attribute__((aligned(64))); +}; + +#endif diff --git a/include/libnftnl/Makefile.am b/include/libnftnl/Makefile.am index 84f01b6..a3a6fb3 100644 --- a/include/libnftnl/Makefile.am +++ b/include/libnftnl/Makefile.am @@ -7,4 +7,5 @@ pkginclude_HEADERS = batch.h \ set.h \ ruleset.h \ common.h \ + attr.h \ gen.h diff --git a/include/libnftnl/attr.h b/include/libnftnl/attr.h new file mode 100644 index 0000000..a99185a --- /dev/null +++ b/include/libnftnl/attr.h @@ -0,0 +1,59 @@ +#ifndef _LIBNFTNL_ATTR_H_ +#define _LIBNFTNL_ATTR_H_ + +#include <stdio.h> +#include <stdint.h> + +/* + * nftnl attributes API + */ +struct nftnl_attr; +struct nftnl_attrbuf; + +/* nftnl_attrbuf */ +struct nftnl_attrbuf *nftnl_attrbuf_alloc(size_t data_size); +void nftnl_attrbuf_free(struct nftnl_attrbuf *attrbuf); +size_t nftnl_attrbuf_get_len(const struct nftnl_attrbuf *attrbuf); +size_t nftnl_attrbuf_get_size(const struct nftnl_attrbuf *attrbuf); +void *nftnl_attrbuf_get_data(const struct nftnl_attrbuf *attrbuf); +void nftnl_attrbuf_copy_data(struct nftnl_attrbuf *attrbuf, + const void *data, size_t len); +struct nftnl_attr *nftnl_attrbuf_get_start(const struct nftnl_attrbuf *attrbuf); +struct nftnl_attr *nftnl_attrbuf_get_end(const struct nftnl_attrbuf *attrbuf); + +/* TLV attribute getters */ +uint8_t nftnl_attr_get_type(const struct nftnl_attr *attr); +uint8_t nftnl_attr_get_len(const struct nftnl_attr *attr); +void *nftnl_attr_get_value(const struct nftnl_attr *attr); + +/* TLV attribute putters */ +struct nftnl_attr *nftnl_attr_put(struct nftnl_attrbuf *attrbuf, + uint8_t type, uint8_t len, const void *value); +struct nftnl_attr *nftnl_attr_put_check(struct nftnl_attrbuf *attrbuf, + uint8_t type, size_t len, + const void *value); + +enum nftnl_attr_data_type { + NFTNL_ATTR_TYPE_COMMENT, + __NFTNL_ATTR_TYPE_MAX, +}; +#define NFTNL_ATTR_TYPE_MAX (__NFTNL_ATTR_TYPE_MAX - 1) + +/* TLV iterators */ +struct nftnl_attr *nftnl_attr_next(const struct nftnl_attr *attr); + +#define nftnl_attr_for_each(attr, attrbuf) \ + for ((attr) = nftnl_attrbuf_get_start(attrbuf); \ + (char *)(nftnl_attrbuf_get_end(attrbuf)) > (char *)(attr); \ + (attr) = nftnl_attr_next(attr)) + +/* TLV callback-based attribute parsers */ +#define NFTNL_CB_ERROR -1 +#define NFTNL_CB_STOP 0 +#define NFTNL_CB_OK 1 + +typedef int (*nftnl_attr_cb_t)(const struct nftnl_attr *attr, void *data); +int nftnl_attr_parse(const struct nftnl_attrbuf *attrbuf, nftnl_attr_cb_t cb, + void *data); + +#endif /* _LIBNFTNL_ATTR_H_ */ diff --git a/src/Makefile.am b/src/Makefile.am index a27e292..621dd69 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -19,6 +19,7 @@ libnftnl_la_SOURCES = utils.c \ ruleset.c \ mxml.c \ jansson.c \ + attr.c \ expr.c \ expr_ops.c \ expr/bitwise.c \ diff --git a/src/attr.c b/src/attr.c new file mode 100644 index 0000000..82c63aa --- /dev/null +++ b/src/attr.c @@ -0,0 +1,132 @@ +#include <libnftnl/attr.h> +#include <attr.h> +#include <utils.h> + +#include <stdlib.h> +#include <stdint.h> + + +struct nftnl_attrbuf *nftnl_attrbuf_alloc(size_t data_size) +{ + struct nftnl_attrbuf *attrbuf; + + attrbuf = (struct nftnl_attrbuf *) + malloc(sizeof(struct nftnl_attrbuf) + data_size); + attrbuf->size = data_size; + attrbuf->end = attrbuf->data; + + return attrbuf; +} +EXPORT_SYMBOL(nftnl_attrbuf_alloc); + +void nftnl_attrbuf_free(struct nftnl_attrbuf *attrbuf) +{ + attrbuf->size = 0; + attrbuf->end = NULL; + free((void *)attrbuf); +} +EXPORT_SYMBOL(nftnl_attrbuf_free); + +size_t nftnl_attrbuf_get_len(const struct nftnl_attrbuf *attrbuf) +{ + return (size_t)(attrbuf->end - attrbuf->data); +} +EXPORT_SYMBOL(nftnl_attrbuf_get_len); + +size_t nftnl_attrbuf_get_size(const struct nftnl_attrbuf *attrbuf) +{ + return attrbuf->size; +} +EXPORT_SYMBOL(nftnl_attrbuf_get_size); + +struct nftnl_attr *nftnl_attrbuf_get_start(const struct nftnl_attrbuf *attrbuf) +{ + return (struct nftnl_attr *)attrbuf->data; +} +EXPORT_SYMBOL(nftnl_attrbuf_get_start); + +struct nftnl_attr *nftnl_attrbuf_get_end(const struct nftnl_attrbuf *attrbuf) +{ + return (struct nftnl_attr *)attrbuf->end; +} +EXPORT_SYMBOL(nftnl_attrbuf_get_end); + +void *nftnl_attrbuf_get_data(const struct nftnl_attrbuf *attrbuf) +{ + return (void *)attrbuf->data; +} +EXPORT_SYMBOL(nftnl_attrbuf_get_data); + +void nftnl_attrbuf_copy_data(struct nftnl_attrbuf *attrbuf, + const void *data, size_t len) +{ + memcpy(attrbuf->data, data, len <= attrbuf->size ? len : attrbuf->size); + attrbuf->end = attrbuf->data + len; +} +EXPORT_SYMBOL(nftnl_attrbuf_copy_data); + +uint8_t nftnl_attr_get_type(const struct nftnl_attr *attr) +{ + return attr->type; +} +EXPORT_SYMBOL(nftnl_attr_get_type); + +uint8_t nftnl_attr_get_len(const struct nftnl_attr *attr) +{ + return attr->len; +} +EXPORT_SYMBOL(nftnl_attr_get_len); + +void *nftnl_attr_get_value(const struct nftnl_attr *attr) +{ + return (void *)attr->value; +} +EXPORT_SYMBOL(nftnl_attr_get_value); + +struct nftnl_attr *nftnl_attr_put(struct nftnl_attrbuf *attrbuf, + uint8_t type, uint8_t len, const void *value) +{ + struct nftnl_attr *attr = (struct nftnl_attr *)attrbuf->end; + + attr->len = len; + attr->type = type; + memcpy(attr->value, value, len); + + attrbuf->end = (char *)nftnl_attr_next(attr); + + return attr; +} +EXPORT_SYMBOL(nftnl_attr_put); + +struct nftnl_attr *nftnl_attr_put_check(struct nftnl_attrbuf *attrbuf, + uint8_t type, size_t len, + const void *value) +{ + /* Check if there is enough space */ + if (attrbuf->size < len + sizeof(struct nftnl_attr)) + return NULL; + + return nftnl_attr_put(attrbuf, type, len, value); +} +EXPORT_SYMBOL(nftnl_attr_put_check); + +struct nftnl_attr *nftnl_attr_next(const struct nftnl_attr *attr) +{ + return (struct nftnl_attr *)&attr->value[attr->len]; +} +EXPORT_SYMBOL(nftnl_attr_next); + +int nftnl_attr_parse(const struct nftnl_attrbuf *attrbuf, nftnl_attr_cb_t cb, + void *data) +{ + int ret = NFTNL_CB_OK; + const struct nftnl_attr *attr; + + nftnl_attr_for_each(attr, attrbuf) { + ret = cb(attr, data); + if (ret <= NFTNL_CB_STOP) + return ret; + } + return ret; +} +EXPORT_SYMBOL(nftnl_attr_parse); diff --git a/src/libnftnl.map b/src/libnftnl.map index 2e193b7..65bd37e 100644 --- a/src/libnftnl.map +++ b/src/libnftnl.map @@ -336,6 +336,22 @@ global: nftnl_set_snprintf; nftnl_set_fprintf; + nftnl_attrbuf_alloc; + nftnl_attrbuf_free; + nftnl_attrbuf_get_len; + nftnl_attrbuf_get_size; + nftnl_attrbuf_get_data; + nftnl_attrbuf_copy_data; + nftnl_attrbuf_get_start; + nftnl_attrbuf_get_end; + nftnl_attr_get_type; + nftnl_attr_get_len; + nftnl_attr_get_value; + nftnl_attr_put; + nftnl_attr_put_check; + nftnl_attr_next; + nftnl_attr_parse; + nftnl_set_list_alloc; nftnl_set_list_free; nftnl_set_list_add; -- 2.7.0 -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html