From 5c3bc232dc9d1dd01d589fab096f67d944621fc2 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Carlos=20Falgueras=20Garc=C3=ADa?= Date: Tue, 22 Mar 2016 20:46:24 +0100 Subject: udata: add TLV user data infrastructure MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit These functions allow to create a buffer (struct nftnl_udata_buf) of user data attributes in TLV format (struct nftnl_udata). It is inspired by libmnl/src/attr.c. It can be used to store several TLVs sequentially into an object. Example: struct nftnl_udata_buf *buf; struct nftnl_udata *attr; const char *str = "Hello World!"; buf = nftnl_udata_buf_alloc(UDATA_SIZE); if (!buf) { perror("OOM"); exit(EXIT_FAILURE); } if (!nftnl_udata_put_strz(buf, MY_TYPE, str)) { perror("Can't put attribute \"%s\"", str); exit(EXIT_FAILURE); } nftnl_udata_for_each(buf, attr) printf("%s\n", (char *)nftnl_udata_attr_value(attr)); nftnl_udata_buf_free(buf); Signed-off-by: Carlos Falgueras García Signed-off-by: Pablo Neira Ayuso --- include/udata.h | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 include/udata.h (limited to 'include/udata.h') diff --git a/include/udata.h b/include/udata.h new file mode 100644 index 0000000..407a3b9 --- /dev/null +++ b/include/udata.h @@ -0,0 +1,40 @@ +#ifndef _LIBNFTNL_UDATA_INTERNAL_H_ +#define _LIBNFTNL_UDATA_INTERNAL_H_ + +#include +#include + +/* + * TLV structures: + * nftnl_udata + * <-------- HEADER --------> <------ PAYLOAD ------> + * +------------+-------------+- - - - - - - - - - - -+ + * | type | len | value | + * | (1 byte) | (1 byte) | | + * +--------------------------+- - - - - - - - - - - -+ + * <-- sizeof(nftnl_udata) -> <-- nftnl_udata->len --> + */ +struct nftnl_udata { + uint8_t type; + uint8_t len; + unsigned char value[]; +} __attribute__((__packed__)); + +/* + * +---------------------------------++ + * | data[] || + * | || || + * | \/ \/ + * +-------+-------+-------+-------+ ... +-------+- - - - - - -+ + * | size | end | TLV | TLV | | TLV | Empty | + * +-------+-------+-------+-------+ ... +-------+- - - - - - -+ + * |<---- nftnl_udata_len() ---->| + * |<----------- nftnl_udata_size() ---------->| + */ +struct nftnl_udata_buf { + uint32_t size; + char *end; + char data[]; +}; + +#endif /* _LIBNFTNL_UDATA_INTERNAL_H_ */ -- cgit v1.2.3