Re: [PATCH 2/3 v2] libnftnl: rule: Change the "userdata" attribute to use new TLV buffer.

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On Mon, Feb 29, 2016 at 05:25:39PM +0100, Carlos Falgueras García wrote:
> Now is it possible to store multiple variable length user data into a rule.
> Modify XML and JSON parsers to support this new feature.
> 
> Signed-off-by: Carlos Falgueras García <carlosfg@xxxxxxxxxx>
> ---
>  include/json.h  |   7 ++
>  include/utils.h |   2 +
>  include/xml.h   |   5 ++
>  src/jansson.c   |  41 +++++++++
>  src/mxml.c      |  39 ++++++++
>  src/rule.c      | 271 ++++++++++++++++++++++++++++++++++++++++++++++++++------
>  src/utils.c     |  45 ++++++++++
>  7 files changed, 385 insertions(+), 25 deletions(-)
> 
> diff --git a/include/json.h b/include/json.h
> index bd70cec..8b64f00 100644
> --- a/include/json.h
> +++ b/include/json.h
> @@ -3,6 +3,7 @@
>  
>  #ifdef JSON_PARSING
>  #include <jansson.h>
> +#include <libnftnl/attr.h>
>  #include <stdbool.h>
>  #include "common.h"
>  
> @@ -51,6 +52,12 @@ int nftnl_jansson_parse_elem(struct nftnl_set *s, json_t *tree,
>  
>  int nftnl_data_reg_json_parse(union nftnl_data_reg *reg, json_t *data,
>  			    struct nftnl_parse_err *err);
> +
> +int nftnl_jansson_attr_parse(struct nftnl_attrbuf *attrbuf,
> +			     json_t *root,
> +			     struct nftnl_parse_err *err,
> +			     struct nftnl_set_list *set_list);
> +
>  #else
>  #define json_t void
>  #endif
> diff --git a/include/utils.h b/include/utils.h
> index 0087dbb..1bbabff 100644
> --- a/include/utils.h
> +++ b/include/utils.h
> @@ -69,6 +69,8 @@ enum nftnl_type {
>  int nftnl_strtoi(const char *string, int base, void *number, enum nftnl_type type);
>  int nftnl_get_value(enum nftnl_type type, void *val, void *out);
>  
> +char *str2value(const char *str, size_t strlen);
> +
>  const char *nftnl_verdict2str(uint32_t verdict);
>  int nftnl_str2verdict(const char *verdict, int *verdict_num);
>  
> diff --git a/include/xml.h b/include/xml.h
> index 7b33a83..a43ea57 100644
> --- a/include/xml.h
> +++ b/include/xml.h
> @@ -4,6 +4,7 @@
>  #ifdef XML_PARSING
>  #include <mxml.h>
>  #include "common.h"
> +#include <libnftnl/attr.h>
>  
>  #define NFTNL_XML_MAND 0
>  #define NFTNL_XML_OPT (1 << 0)
> @@ -51,6 +52,10 @@ int nftnl_mxml_set_parse(mxml_node_t *tree, struct nftnl_set *s,
>  
>  int nftnl_data_reg_xml_parse(union nftnl_data_reg *reg, mxml_node_t *tree,
>  			   struct nftnl_parse_err *err);
> +
> +int nftnl_mxml_attr_parse(struct nftnl_attrbuf *attrbuf, mxml_node_t *tree,
> +			  uint32_t mxml_flags, uint16_t flags,
> +			  struct nftnl_parse_err *err);
>  #else
>  #define mxml_node_t void
>  #endif
> diff --git a/src/jansson.c b/src/jansson.c
> index 3476ed2..9fff7b5 100644
> --- a/src/jansson.c
> +++ b/src/jansson.c
> @@ -19,6 +19,7 @@
>  #include <libnftnl/set.h>
>  
>  #include <libnftnl/expr.h>
> +#include <libnftnl/attr.h>
>  #include <linux/netfilter/nf_tables.h>
>  
>  #ifdef JSON_PARSING
> @@ -276,4 +277,44 @@ int nftnl_jansson_set_elem_parse(struct nftnl_set_elem *e, json_t *root,
>  
>  	return 0;
>  }
> +
> +int nftnl_jansson_attr_parse(struct nftnl_attrbuf *attrbuf,
> +			     json_t *root,
> +			     struct nftnl_parse_err *err,
> +			     struct nftnl_set_list *set_list)
> +{
> +	int ret = 0;
> +	uint8_t type;
> +	uint8_t len;
> +	const char *value_str;
> +	char *value = NULL;
> +
> +	ret = nftnl_jansson_parse_val(root, "type", NFTNL_TYPE_U8, &type, err);
> +	if (ret != 0)
> +		return -1;
> +
> +	ret = nftnl_jansson_parse_val(root, "length", NFTNL_TYPE_U8, &len, err);
> +	if (ret != 0)
> +		return -1;
> +
> +	value_str = nftnl_jansson_parse_str(root, "value", err);
> +	if (ret != 0)
> +		return -1;
> +
> +	if (strlen(value_str) != 2*len)
> +		return -1;
> +
> +	value = str2value(value_str, 2*len);
> +	if (!value) {
> +		perror("nftnl_jansson_attr_parse");
> +		exit(EXIT_FAILURE);

You shouldn't call exit() in a library.

Please, pass up the error code as return value.

> +	}
> +
> +	if (!nftnl_attr_put_check(attrbuf, type, len, (void *)value))
> +		ret = -1;
> +
> +	free(value);
> +	return ret;
> +}
> +
>  #endif
> diff --git a/src/mxml.c b/src/mxml.c
> index 51dbf1b..793a89d 100644
> --- a/src/mxml.c
> +++ b/src/mxml.c
> @@ -229,4 +229,43 @@ int nftnl_mxml_family_parse(mxml_node_t *tree, const char *node_name,
>  
>  	return family;
>  }
> +
> +int nftnl_mxml_attr_parse(struct nftnl_attrbuf *attrbuf, mxml_node_t *tree,
> +			  uint32_t mxml_flags, uint16_t flags,
> +			  struct nftnl_parse_err *err)
> +{
> +	int ret = 0;
> +	uint8_t len;
> +	uint8_t type;
> +	const char *value_str;
> +	char *value = NULL;
> +
> +	if (nftnl_mxml_num_parse(tree, "type", mxml_flags, BASE_DEC, &type,
> +				 NFTNL_TYPE_U8, flags, err) < 0)
> +		return -1;
> +
> +	if (nftnl_mxml_num_parse(tree, "length", mxml_flags, BASE_DEC, &len,
> +				 NFTNL_TYPE_U8, flags, err) < 0)
> +		return -1;
> +
> +	value_str = nftnl_mxml_str_parse(tree, "value", mxml_flags, flags, err);
> +	if (value_str == NULL)
> +		return -1;
> +
> +	if (strlen(value_str) != 2*len)
> +		return -1;
> +
> +	value = str2value(value_str, 2*len);
> +	if (!value) {
> +		perror("nftnl_mxml_attr_parse");
> +		exit(EXIT_FAILURE);
> +	}
> +
> +	if (!nftnl_attr_put_check(attrbuf, type, len, (void *)value))
> +		ret = -1;
> +
> +	free(value);
> +	return ret;
> +}
> +
>  #endif
> diff --git a/src/rule.c b/src/rule.c
> index 3a32bf6..4a5dc8c 100644
> --- a/src/rule.c
> +++ b/src/rule.c
> @@ -19,7 +19,6 @@
>  #include <netinet/in.h>
>  #include <errno.h>
>  #include <inttypes.h>
> -#include <ctype.h>
>  
>  #include <libmnl/libmnl.h>
>  #include <linux/netfilter/nfnetlink.h>
> @@ -28,6 +27,7 @@
>  #include <libnftnl/rule.h>
>  #include <libnftnl/set.h>
>  #include <libnftnl/expr.h>
> +#include <libnftnl/attr.h>
>  
>  struct nftnl_rule {
>  	struct list_head head;
> @@ -38,10 +38,7 @@ struct nftnl_rule {
>  	const char	*chain;
>  	uint64_t	handle;
>  	uint64_t	position;
> -	struct {
> -			void		*data;
> -			uint32_t	len;
> -	} user;
> +	struct nftnl_attrbuf	*userdata;
>  	struct {
>  			uint32_t	flags;
>  			uint32_t	proto;
> @@ -50,6 +47,15 @@ struct nftnl_rule {
>  	struct list_head expr_list;
>  };
>  
> +static size_t nftnl_rule_snprintf_data2str(char *buf, size_t size,
> +					   const void *data, size_t datalen);
> +static size_t nftnl_rule_snprintf_default_attr(char *buf, size_t size,
> +					       const struct nftnl_attr *attr);
> +static size_t nftnl_rule_snprintf_xml_attr(char *buf, size_t size,
> +					   const struct nftnl_attr *attr);
> +static size_t nftnl_rule_snprintf_json_attr(char *buf, size_t size,
> +					    const struct nftnl_attr *attr);
> +
>  struct nftnl_rule *nftnl_rule_alloc(void)
>  {
>  	struct nftnl_rule *r;
> @@ -75,6 +81,8 @@ void nftnl_rule_free(struct nftnl_rule *r)
>  		xfree(r->table);
>  	if (r->chain != NULL)
>  		xfree(r->chain);
> +	if (r->flags & (1 << NFTNL_RULE_USERDATA))
> +		nftnl_attrbuf_free(r->userdata);
>  
>  	xfree(r);
>  }
> @@ -162,8 +170,12 @@ void nftnl_rule_set_data(struct nftnl_rule *r, uint16_t attr,
>  		r->position = *((uint64_t *)data);
>  		break;
>  	case NFTNL_RULE_USERDATA:
> -		r->user.data = (void *)data;
> -		r->user.len = data_len;
> +		(r->userdata = nftnl_attrbuf_alloc(data_len));
> +		if (!r->userdata) {
> +			perror("nftnl_rule_set_data - userdata");
> +			exit(EXIT_FAILURE);
> +		}
> +		nftnl_attrbuf_copy_data(r->userdata, data, data_len);
>  		break;
>  	}
>  	r->flags |= (1 << attr);
> @@ -221,8 +233,8 @@ const void *nftnl_rule_get_data(const struct nftnl_rule *r, uint16_t attr,
>  		*data_len = sizeof(uint64_t);
>  		return &r->position;
>  	case NFTNL_RULE_USERDATA:
> -		*data_len = r->user.len;
> -		return r->user.data;
> +		*data_len = nftnl_attrbuf_get_len(r->userdata);
> +		return (void *)nftnl_attrbuf_get_data(r->userdata);
>  	}
>  	return NULL;
>  }
> @@ -288,8 +300,9 @@ void nftnl_rule_nlmsg_build_payload(struct nlmsghdr *nlh, struct nftnl_rule *r)
>  	if (r->flags & (1 << NFTNL_RULE_POSITION))
>  		mnl_attr_put_u64(nlh, NFTA_RULE_POSITION, htobe64(r->position));
>  	if (r->flags & (1 << NFTNL_RULE_USERDATA)) {
> -		mnl_attr_put(nlh, NFTA_RULE_USERDATA, r->user.len,
> -			     r->user.data);
> +		mnl_attr_put(nlh, NFTA_RULE_USERDATA,
> +			     nftnl_attrbuf_get_len(r->userdata),
> +			     nftnl_attrbuf_get_data(r->userdata));
>  	}
>  
>  	if (!list_empty(&r->expr_list)) {
> @@ -447,19 +460,17 @@ int nftnl_rule_nlmsg_parse(const struct nlmsghdr *nlh, struct nftnl_rule *r)
>  		r->flags |= (1 << NFTNL_RULE_POSITION);
>  	}
>  	if (tb[NFTA_RULE_USERDATA]) {
> +		uint16_t udata_size;
>  		const void *udata =
>  			mnl_attr_get_payload(tb[NFTA_RULE_USERDATA]);
>  
> -		if (r->user.data)
> -			xfree(r->user.data);
> -
> -		r->user.len = mnl_attr_get_payload_len(tb[NFTA_RULE_USERDATA]);
> +		udata_size = mnl_attr_get_payload_len(tb[NFTA_RULE_USERDATA]);
>  
> -		r->user.data = malloc(r->user.len);
> -		if (r->user.data == NULL)
> +		(r->userdata = nftnl_attrbuf_alloc(udata_size));
> +		if (!r->userdata)
>  			return -1;
> +		nftnl_attrbuf_copy_data(r->userdata, udata, udata_size);
>  
> -		memcpy(r->user.data, udata, r->user.len);
>  		r->flags |= (1 << NFTNL_RULE_USERDATA);
>  	}
>  
> @@ -481,6 +492,7 @@ int nftnl_jansson_parse_rule(struct nftnl_rule *r, json_t *tree,
>  	uint64_t uval64;
>  	uint32_t uval32;
>  	int i, family;
> +	struct nftnl_attrbuf *attrbuf;
>  
>  	root = nftnl_jansson_get_node(tree, "rule", err);
>  	if (root == NULL)
> @@ -557,6 +569,31 @@ int nftnl_jansson_parse_rule(struct nftnl_rule *r, json_t *tree,
>  		nftnl_rule_add_expr(r, e);
>  	}
>  

Please, wrap these code below into a function, eg. nftnl_jansson_udata_parse()

> +	array = json_object_get(root, "userdata");
> +	if (array == NULL) {
> +		err->error = NFTNL_PARSE_EMISSINGNODE;
> +		err->node_name = "userdata";
> +		goto err;
> +	}
> +
> +	attrbuf = nftnl_attrbuf_alloc(NFT_USERDATA_MAXLEN);
> +	if (!attrbuf) {
> +		perror("nftnl_jansson_parse_rule");
> +		exit(EXIT_FAILURE);
> +	}
> +
> +	for (i = 0; i < json_array_size(array); ++i) {
> +		if (nftnl_jansson_attr_parse(attrbuf,
> +					     json_array_get(array, i),
> +					     err,
> +					     set_list) < 0)
> +			goto err;
> +	}
> +
> +	nftnl_rule_set_data(r, NFTNL_RULE_USERDATA,
> +			    nftnl_attrbuf_get_data(attrbuf),
> +			    nftnl_attrbuf_get_len(attrbuf));
> +
>  	return 0;
>  err:
>  	return -1;
> @@ -592,7 +629,7 @@ int nftnl_mxml_rule_parse(mxml_node_t *tree, struct nftnl_rule *r,
>  			struct nftnl_parse_err *err,
>  			struct nftnl_set_list *set_list)
>  {
> -	mxml_node_t *node;
> +	mxml_node_t *node, *node_ud;
>  	struct nftnl_expr *e;
>  	const char *table, *chain;
>  	int family;
> @@ -649,6 +686,35 @@ int nftnl_mxml_rule_parse(mxml_node_t *tree, struct nftnl_rule *r,
>  		nftnl_rule_add_expr(r, e);
>  	}
>  
> +	node_ud = mxmlFindElement(tree, tree, "userdata", NULL, NULL,
> +				  MXML_DESCEND);
> +	if (node_ud) {

Please, wrap these code below into a function, eg. nftnl_mxml_udata_parse()

> +		struct nftnl_attrbuf *attrbuf;
> +
> +		attrbuf = nftnl_attrbuf_alloc(NFT_USERDATA_MAXLEN);
> +		if (!attrbuf) {
> +			perror("nftnl_mxml_rule_parse");
> +			exit(EXIT_FAILURE);
> +		}
> +
> +		/* Iterate over attributes */
> +		for (
> +			node = mxmlFindElement(node_ud, node_ud, "attr", NULL,
> +				NULL, MXML_DESCEND);
> +			node != NULL;
> +			node = mxmlFindElement(node, node_ud, "attr", NULL,
> +				NULL, MXML_DESCEND)
> +		) {
> +			if (nftnl_mxml_attr_parse(attrbuf, node,
> +					MXML_DESCEND_FIRST, r->flags, err) < 0)
> +				return -1;
> +		}
> +
> +		nftnl_rule_set_data(r, NFTNL_RULE_USERDATA,
> +				    nftnl_attrbuf_get_data(attrbuf),
> +				    nftnl_attrbuf_get_len(attrbuf));
> +	}
> +
>  	return 0;
>  }
>  #endif
> @@ -711,6 +777,21 @@ int nftnl_rule_parse_file(struct nftnl_rule *r, enum nftnl_parse_type type,
>  }
>  EXPORT_SYMBOL_ALIAS(nftnl_rule_parse_file, nft_rule_parse_file);
>  
> +static size_t nftnl_rule_snprintf_data2str(char *buf, size_t size,
> +					   const void *data, size_t datalen)
> +{
> +	int i;
> +	size_t ret, len = size, offset = 0;
> +	const unsigned char *str = data;
> +
> +	for (i = 0; i < datalen; i++) {
> +		ret = snprintf(buf+offset, len, "%02X", str[i]);
> +		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
> +	}
> +
> +	return offset;
> +}
> +
>  static int nftnl_rule_snprintf_json(char *buf, size_t size, struct nftnl_rule *r,
>  					 uint32_t type, uint32_t flags)
>  {
> @@ -757,6 +838,31 @@ static int nftnl_rule_snprintf_json(char *buf, size_t size, struct nftnl_rule *r
>  		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
>  	}
>  
> +	if (r->flags & (1 << NFTNL_RULE_USERDATA)) {
> +		const struct nftnl_attr *attr;
> +
> +		ret = snprintf(buf+offset, len, "\"userdata\":[");
> +		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
> +
> +		nftnl_attr_for_each(attr, r->userdata) {
> +			ret = nftnl_rule_snprintf_json_attr(buf+offset, len,
> +							    attr);
> +			SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
> +
> +			ret = snprintf(buf+offset, len, ",");
> +			SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
> +		}
> +		/* delete last comma */
> +		buf[offset-1] = '\0';
> +		offset--;
> +		size--;
> +		len++;
> +
> +		ret = snprintf(buf+offset, len, "],\n");
> +		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
> +
> +	}
> +
>  	ret = snprintf(buf+offset, len, "\"expr\":[");
>  	SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
>  
> @@ -849,17 +955,123 @@ static int nftnl_rule_snprintf_xml(char *buf, size_t size, struct nftnl_rule *r,
>  		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
>  
>  	}
> +
> +	if (r->flags & (1 << NFTNL_RULE_USERDATA)) {
> +		const struct nftnl_attr *attr;
> +
> +		ret = snprintf(buf+offset, len, "<userdata>");
> +		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
> +
> +		nftnl_attr_for_each(attr, r->userdata) {
> +			ret = snprintf(buf+offset, len, "<attr>");
> +			SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
> +
> +			ret = nftnl_rule_snprintf_xml_attr(buf+offset, len,
> +							    attr);
> +			SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
> +
> +			ret = snprintf(buf+offset, len, "</attr>");
> +			SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
> +		}
> +
> +		ret = snprintf(buf+offset, len, "</userdata>");
> +		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
> +	}
> +
>  	ret = snprintf(buf+offset, len, "</rule>");
>  	SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
>  
>  	return offset;
>  }
>  
> +static size_t nftnl_rule_snprintf_xml_attr(char *buf, size_t size,
> +					   const struct nftnl_attr *attr)
[...]
> +static size_t nftnl_rule_snprintf_json_attr(char *buf, size_t size,
> +					    const struct nftnl_attr *attr)

You can consolidate these two functions into one using the NFTNL_BUF_*
API.

> diff --git a/src/utils.c b/src/utils.c
> index ba36bc4..0cac4b6 100644
> --- a/src/utils.c
> +++ b/src/utils.c
> @@ -139,6 +139,51 @@ int nftnl_strtoi(const char *string, int base, void *out, enum nftnl_type type)
>  	return ret;
>  }
>  
> +static int hex2char(char *out, char c)
> +{
> +	/* numbers */
> +	if (c >= 0x30 && c <= 0x39)
> +		*out = c - 0x30;
> +	/* lowercase characters */
> +	else if (c >= 0x61 && c <= 0x66)
> +		*out = c - 0x61 + 10;
> +	/* uppercase characters */
> +	else if (c >= 0x41 && c <= 0x46)
> +		*out = c - 0x41 + 10;
> +	else {
> +		errno = EINVAL;
> +		return 0;
> +	}

You can just print data in hexadecimal, so we can get rid of this.
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