These functions allow to create a buffer (nftnl_udata_buf) of TLV objects
(nftnl_udata). 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_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 <carlo...@riseup.net>
---
include/Makefile.am | 1 +
include/libnftnl/Makefile.am | 1 +
include/libnftnl/udata.h | 54 ++++++++++++++++++
include/udata.h | 40 +++++++++++++
src/Makefile.am | 1 +
src/libnftnl.map | 16 ++++++
src/udata.c | 131 +++++++++++++++++++++++++++++++++++++++++++
7 files changed, 244 insertions(+)
create mode 100644 include/libnftnl/udata.h
create mode 100644 include/udata.h
create mode 100644 src/udata.c
diff --git a/include/Makefile.am b/include/Makefile.am
index be9eb9b..9f55737 100644
--- a/include/Makefile.am
+++ b/include/Makefile.am
@@ -12,4 +12,5 @@ noinst_HEADERS = internal.h \
expr.h \
json.h \
set_elem.h \
+ udata.h \
utils.h
diff --git a/include/libnftnl/Makefile.am b/include/libnftnl/Makefile.am
index 84f01b6..457ec95 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 \
+ udata.h \
gen.h
diff --git a/include/libnftnl/udata.h b/include/libnftnl/udata.h
new file mode 100644
index 0000000..166bb06
--- /dev/null
+++ b/include/libnftnl/udata.h
@@ -0,0 +1,54 @@
+#ifndef _LIBNFTNL_UDATA_H_
+#define _LIBNFTNL_UDATA_H_
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+/*
+ * nftnl user data attributes API
+ */
+struct nftnl_udata;
+struct nftnl_udata_buf;
+
+/* nftnl_udata_buf */
+struct nftnl_udata_buf *nftnl_udata_buf_alloc(uint32_t data_size);
+void nftnl_udata_buf_free(struct nftnl_udata_buf *buf);
+uint32_t nftnl_udata_buf_len(const struct nftnl_udata_buf *buf);
+uint32_t nftnl_udata_buf_size(const struct nftnl_udata_buf *buf);
+void *nftnl_udata_buf_data(const struct nftnl_udata_buf *buf);
+void nftnl_udata_buf_put(struct nftnl_udata_buf *buf, const void *data,
+ uint32_t len);
+struct nftnl_udata *nftnl_udata_start(const struct nftnl_udata_buf *buf);
+struct nftnl_udata *nftnl_udata_end(const struct nftnl_udata_buf *buf);
+
+/* putters */
+bool nftnl_udata_put(struct nftnl_udata_buf *buf, uint8_t type, uint32_t len,
+ const void *value);
+bool nftnl_udata_put_strz(struct nftnl_udata_buf *buf, uint8_t type,
+ const char *strz);
+
+/* nftnl_udata_attr */
+uint8_t nftnl_udata_attr_type(const struct nftnl_udata *attr);
+uint8_t nftnl_udata_attr_len(const struct nftnl_udata *attr);
+void *nftnl_udata_attr_value(const struct nftnl_udata *attr);
+
+/* iterator */
+struct nftnl_udata *nftnl_udata_attr_next(const struct nftnl_udata *attr);
+
+#define nftnl_udata_for_each(buf, attr) \
+ for ((attr) = nftnl_udata_start(buf); \
+ (char *)(nftnl_udata_end(buf)) > (char *)(attr); \
+ (attr) = nftnl_udata_attr_next(attr))
+
+#define nftnl_udata_for_each_data(data, data_len, attr) \
+ for ((attr) = (struct nftnl_udata *)(data); \
+ (char *)(data + data_len) > (char *)(attr); \
+ (attr) = nftnl_udata_attr_next(attr))
+
+typedef int (*nftnl_udata_cb_t)(const struct nftnl_udata *attr,
+ void *data);
+int nftnl_udata_parse(const void *data, uint32_t data_len, nftnl_udata_cb_t cb,
+ void *cb_data);
+
+#endif /* _LIBNFTNL_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 <stdint.h>
+#include <stddef.h>
+
+/*
+ * 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_ */
diff --git a/src/Makefile.am b/src/Makefile.am
index a27e292..7e580e4 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -19,6 +19,7 @@ libnftnl_la_SOURCES = utils.c \
ruleset.c \
mxml.c \
jansson.c \
+ udata.c \
expr.c \
expr_ops.c \
expr/bitwise.c \
diff --git a/src/libnftnl.map b/src/libnftnl.map
index 2e193b7..b2e2326 100644
--- a/src/libnftnl.map
+++ b/src/libnftnl.map
@@ -512,4 +512,20 @@ LIBNFTNL_4.1 {
nftnl_trace_get_data;
nftnl_trace_nlmsg_parse;
+
+ nftnl_udata_buf_alloc;
+ nftnl_udata_buf_free;
+ nftnl_udata_buf_len;
+ nftnl_udata_buf_size;
+ nftnl_udata_buf_data;
+ nftnl_udata_buf_put;
+ nftnl_udata_start;
+ nftnl_udata_end;
+ nftnl_udata_put;
+ nftnl_udata_put_strz;
+ nftnl_udata_attr_type;
+ nftnl_udata_attr_len;
+ nftnl_udata_attr_value;
+ nftnl_udata_attr_next;
+ nftnl_udata_parse;
} LIBNFTNL_4;
diff --git a/src/udata.c b/src/udata.c
new file mode 100644
index 0000000..afe9057
--- /dev/null
+++ b/src/udata.c
@@ -0,0 +1,131 @@
+#include <libnftnl/udata.h>
+#include <udata.h>
+#include <utils.h>
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+
+struct nftnl_udata_buf *nftnl_udata_buf_alloc(uint32_t data_size)
+{
+ struct nftnl_udata_buf *buf;
+
+ buf = malloc(sizeof(struct nftnl_udata_buf) + data_size);
+ if (!buf)
+ return NULL;
+ buf->size = data_size;
+ buf->end = buf->data;
+
+ return buf;
+}
+EXPORT_SYMBOL(nftnl_udata_buf_alloc);
+
+void nftnl_udata_buf_free(struct nftnl_udata_buf *buf)
+{
+ free(buf);
+}
+EXPORT_SYMBOL(nftnl_udata_buf_free);
+
+uint32_t nftnl_udata_buf_len(const struct nftnl_udata_buf *buf)
+{
+ return (uint32_t)(buf->end - buf->data);
+}
+EXPORT_SYMBOL(nftnl_udata_buf_len);
+
+uint32_t nftnl_udata_buf_size(const struct nftnl_udata_buf *buf)
+{
+ return buf->size;
+}
+EXPORT_SYMBOL(nftnl_udata_buf_size);
+
+void *nftnl_udata_buf_data(const struct nftnl_udata_buf *buf)
+{
+ return (void *)buf->data;
+}
+EXPORT_SYMBOL(nftnl_udata_buf_data);
+
+void nftnl_udata_buf_put(struct nftnl_udata_buf *buf, const void *data,
+ uint32_t len)
+{
+ memcpy(buf->data, data, len <= buf->size ? len : buf->size);
+ buf->end = buf->data + len;
+}
+EXPORT_SYMBOL(nftnl_udata_buf_put);
+
+struct nftnl_udata *nftnl_udata_start(const struct nftnl_udata_buf *buf)
+{
+ return (struct nftnl_udata *)buf->data;
+}
+EXPORT_SYMBOL(nftnl_udata_start);
+
+struct nftnl_udata *nftnl_udata_end(const struct nftnl_udata_buf *buf)
+{
+ return (struct nftnl_udata *)buf->end;
+}
+EXPORT_SYMBOL(nftnl_udata_end);
+
+bool nftnl_udata_put(struct nftnl_udata_buf *buf, uint8_t type, uint32_t len,
+ const void *value)
+{
+ struct nftnl_udata *attr;
+
+ if (buf->size < len + sizeof(struct nftnl_udata))
+ return false;
+
+ attr = (struct nftnl_udata *)buf->end;
+ attr->len = len;
+ attr->type = type;
+ memcpy(attr->value, value, len);
+
+ buf->end = (char *)nftnl_udata_attr_next(attr);
+
+ return true;
+}
+EXPORT_SYMBOL(nftnl_udata_put);
+
+bool nftnl_udata_put_strz(struct nftnl_udata_buf *buf, uint8_t type,
+ const char *strz)
+{
+ return nftnl_udata_put(buf, type, strlen(strz) + 1, strz);
+}
+EXPORT_SYMBOL(nftnl_udata_put_strz);
+
+uint8_t nftnl_udata_attr_type(const struct nftnl_udata *attr)
+{
+ return attr->type;
+}
+EXPORT_SYMBOL(nftnl_udata_attr_type);
+
+uint8_t nftnl_udata_attr_len(const struct nftnl_udata *attr)
+{
+ return attr->len;
+}
+EXPORT_SYMBOL(nftnl_udata_attr_len);
+
+void *nftnl_udata_attr_value(const struct nftnl_udata *attr)
+{
+ return (void *)attr->value;
+}
+EXPORT_SYMBOL(nftnl_udata_attr_value);
+
+struct nftnl_udata *nftnl_udata_attr_next(const struct nftnl_udata *attr)
+{
+ return (struct nftnl_udata *)&attr->value[attr->len];
+}
+EXPORT_SYMBOL(nftnl_udata_attr_next);
+
+int nftnl_udata_parse(const void *data, uint32_t data_len, nftnl_udata_cb_t cb,
+ void *cb_data)
+{
+ int ret = 0;
+ const struct nftnl_udata *attr;
+
+ nftnl_udata_for_each_data(data, data_len, attr) {
+ ret = cb(attr, cb_data);
+ if (ret <= 0)
+ return ret;
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(nftnl_udata_parse);
--
2.7.2
--
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