[libnftnl PATCH 0/2] Do not print unset value in xml file

[libnftnl PATCH 0/2] Do not print unset value in xml file

[Ana Rey]

In this patchset I refector the nft_rule_expr_log_snprintf function and
after, I fix a problem with unset values in xml file.

Ana Rey (2):
  src: expr: log: Code refactoring in nft_rule_expr_log_snprintf
  src: expr: log: Do not print unset values in xml.

 src/expr/log.c | 102 +++++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 67 insertions(+), 35 deletions(-)

-- 
2.0.0.rc2

[libnftnl PATCH 1/2] src: expr: log: Code refactoring in nft_rule_expr_log_snprintf

[Ana Rey]

This process adds three new functions:

* nft_rule_expr_log_snprintf_default
* nft_rule_expr_log_snprintf_xml
* nft_rule_expr_log_snprintf_json

Signed-off-by: Ana Rey <anarey@gmail.com>
---
 src/expr/log.c | 58 ++++++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 40 insertions(+), 18 deletions(-)

diff --git a/src/expr/log.c b/src/expr/log.c
index 5119c20..a61a8d3 100644
--- a/src/expr/log.c
+++ b/src/expr/log.c
@@ -243,32 +243,54 @@ static int nft_rule_expr_log_xml_parse(struct nft_rule_expr *e,
 #endif
 }
 
+static int nft_rule_expr_log_snprintf_default(char *buf, size_t len,
+					      struct nft_rule_expr *e)
+{
+	struct nft_expr_log *log = nft_expr_data(e);
+
+	return snprintf(buf, len, "prefix '%s' group %u snaplen %u"
+				  "qthreshold %u ",
+			log->prefix, log->group, log->snaplen, log->qthreshold);
+}
+
+static int nft_rule_expr_log_snprintf_xml(char *buf, size_t size,
+					  struct nft_rule_expr *e)
+{
+	struct nft_expr_log *log = nft_expr_data(e);
+
+	return snprintf(buf, size, "<prefix>%s</prefix>"
+				   "<group>%u</group>"
+				   "<snaplen>%u</snaplen>"
+				   "<qthreshold>%u</qthreshold>",
+			log->prefix, log->group,
+			log->snaplen, log->qthreshold);
+}
+
+static int nft_rule_expr_log_snprintf_json(char *buf, size_t len,
+					   struct nft_rule_expr *e)
+{
+	struct nft_expr_log *log = nft_expr_data(e);
+
+	return snprintf(buf, len, "\"prefix\":\"%s\","
+				  "\"group\":%u,"
+				  "\"snaplen\":%u,"
+				  "\"qthreshold\":%u",
+			log->prefix, log->group,
+			log->snaplen, log->qthreshold);
+}
+
+
 static int
 nft_rule_expr_log_snprintf(char *buf, size_t len, uint32_t type,
 			    uint32_t flags, struct nft_rule_expr *e)
 {
-	struct nft_expr_log *log = nft_expr_data(e);
-
 	switch(type) {
 	case NFT_OUTPUT_DEFAULT:
-		return snprintf(buf, len, "prefix '%s' group %u "
-					  "snaplen %u qthreshold %u ",
-				log->prefix, log->group,
-				log->snaplen, log->qthreshold);
+		return nft_rule_expr_log_snprintf_default(buf, len, e);
 	case NFT_OUTPUT_XML:
-		return snprintf(buf, len, "<prefix>%s</prefix>"
-					  "<group>%u</group>"
-					  "<snaplen>%u</snaplen>"
-					  "<qthreshold>%u</qthreshold>",
-				log->prefix, log->group,
-				log->snaplen, log->qthreshold);
+		return nft_rule_expr_log_snprintf_xml(buf, len, e);
 	case NFT_OUTPUT_JSON:
-		return snprintf(buf, len, "\"prefix\":\"%s\","
-					  "\"group\":%u,"
-					  "\"snaplen\":%u,"
-					  "\"qthreshold\":%u",
-				log->prefix, log->group,
-				log->snaplen, log->qthreshold);
+		return nft_rule_expr_log_snprintf_json(buf, len, e);
 	default:
 		break;
 	}
-- 
2.0.0.rc2

[libnftnl PATCH 2/2] src: expr: log: Do not print unset values in xml.

[Ana Rey]

It changes the parse and the snprint functions to omit unset values.

If we used this rule:
ntt add rule ip test output log

We got this xml file:

<rule><family>ip</family>
<table>test</table>
<chain>output</chain>
<handle>88</handle>
<expr type="log">
	<prefix>(null)</prefix>
	<group>0</group>
	<snaplen>0</snaplen>
	<qthreshold>0</qthreshold>
</expr>
</rule>

And It was imposible import this file.

Now, That rule creates this xml file without null values:

<rule><family>ip</family>
<table>test</table>
<chain>output</chain>
<handle>88</handle>
<expr type="log">
</expr>
</rule>

and It's possible import this xml file.

Signed-off-by: Ana Rey <anarey@gmail.com>
---
 src/expr/log.c | 56 +++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 33 insertions(+), 23 deletions(-)

diff --git a/src/expr/log.c b/src/expr/log.c
index a61a8d3..cd259d4 100644
--- a/src/expr/log.c
+++ b/src/expr/log.c
@@ -209,32 +209,25 @@ static int nft_rule_expr_log_xml_parse(struct nft_rule_expr *e,
 
 	prefix = nft_mxml_str_parse(tree, "prefix", MXML_DESCEND_FIRST,
 				    NFT_XML_MAND, err);
-	if (prefix == NULL)
-		return -1;
-
-	log->prefix = strdup(prefix);
-	e->flags |= (1 << NFT_EXPR_LOG_PREFIX);
+	if (prefix != NULL) {
+		log->prefix = strdup(prefix);
+		e->flags |= (1 << NFT_EXPR_LOG_PREFIX);
+	}
 
 	if (nft_mxml_num_parse(tree, "group", MXML_DESCEND_FIRST, BASE_DEC,
 			       &log->group, NFT_TYPE_U16, NFT_XML_MAND,
-			       err) != 0)
-		return -1;
-
-	e->flags |= (1 << NFT_EXPR_LOG_GROUP);
+			       err) >= 0)
+		e->flags |= (1 << NFT_EXPR_LOG_GROUP);
 
 	if (nft_mxml_num_parse(tree, "snaplen", MXML_DESCEND_FIRST, BASE_DEC,
 			       &log->snaplen, NFT_TYPE_U32, NFT_XML_MAND,
-			       err) != 0)
-		return -1;
-
-	e->flags |= (1 << NFT_EXPR_LOG_SNAPLEN);
+			       err) >= 0)
+		e->flags |= (1 << NFT_EXPR_LOG_SNAPLEN);
 
 	if (nft_mxml_num_parse(tree, "qthreshold", MXML_DESCEND_FIRST,
 			       BASE_DEC, &log->qthreshold,
-			       NFT_TYPE_U16, NFT_XML_MAND, err) != 0)
-		return -1;
-
-	e->flags |= (1 << NFT_EXPR_LOG_QTHRESHOLD);
+			       NFT_TYPE_U16, NFT_XML_MAND, err) >= 0)
+		e->flags |= (1 << NFT_EXPR_LOG_QTHRESHOLD);
 
 	return 0;
 #else
@@ -256,14 +249,31 @@ static int nft_rule_expr_log_snprintf_default(char *buf, size_t len,
 static int nft_rule_expr_log_snprintf_xml(char *buf, size_t size,
 					  struct nft_rule_expr *e)
 {
+	int ret, len = size, offset = 0;
 	struct nft_expr_log *log = nft_expr_data(e);
 
-	return snprintf(buf, size, "<prefix>%s</prefix>"
-				   "<group>%u</group>"
-				   "<snaplen>%u</snaplen>"
-				   "<qthreshold>%u</qthreshold>",
-			log->prefix, log->group,
-			log->snaplen, log->qthreshold);
+	if (e->flags & (1 << NFT_EXPR_LOG_PREFIX)) {
+		ret = snprintf(buf+offset, len, "<prefix>%s</prefix>",
+			       log->prefix);
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+	if (e->flags & (1 << NFT_EXPR_LOG_GROUP)) {
+		ret = snprintf(buf+offset, len, "<group>%u</group>",
+			       log->group);
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+	if (e->flags & (1 << NFT_EXPR_LOG_SNAPLEN)) {
+		ret = snprintf(buf+offset, len, "<snaplen>%u</snaplen>",
+			       log->snaplen);
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+	}
+	if (e->flags & (1 << NFT_EXPR_LOG_QTHRESHOLD)) {
+		ret = snprintf(buf+offset, len, "<qthreshold>%u</qthreshold>",
+			       log->qthreshold);
+		SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+		}
+
+	return offset;
 }
 
 static int nft_rule_expr_log_snprintf_json(char *buf, size_t len,
-- 
2.0.0.rc2

Re: [libnftnl PATCH 2/2] src: expr: log: Do not print unset values in xml.

[Arturo Borrero Gonzalez]

On 29 May 2014 13:26, Ana Rey <anarey@gmail.com> wrote:
> It changes the parse and the snprint functions to omit unset values.
>

Hi Ana,

I like your patches. A minor comment below.

> @@ -209,32 +209,25 @@ static int nft_rule_expr_log_xml_parse(struct nft_rule_expr *e,
>
>         prefix = nft_mxml_str_parse(tree, "prefix", MXML_DESCEND_FIRST,
>                                     NFT_XML_MAND, err);
> -       if (prefix == NULL)
> -               return -1;
> -
> -       log->prefix = strdup(prefix);
> -       e->flags |= (1 << NFT_EXPR_LOG_PREFIX);
> +       if (prefix != NULL) {
> +               log->prefix = strdup(prefix);
> +               e->flags |= (1 << NFT_EXPR_LOG_PREFIX);
> +       }
>

I guess it's time to switch here to nft_expr_attr_set_*() functions.
It was my fault to not use the shortcuts.
I think shortcuts are less error prone and save some lines of code.

Like the JSON parsing code:

if (prefix != NULL)
  nft_rule_expr_set_str(e, NFT_EXPR_LOG_PREFIX, prefix);

BTW, looking at how JSON does it [0], there the prefix element is
mandatory. I think we need to be consistent in both formats, so I
would recommend an additional patch to make prefix optional in the
JSON parser.

regards.

[0] http://git.netfilter.org/libnftnl/tree/src/expr/log.c#n171
-- 
Arturo Borrero González
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Re: [libnftnl PATCH 1/2] src: expr: log: Code refactoring in nft_rule_expr_log_snprintf

[Pablo Neira Ayuso]

On Thu, May 29, 2014 at 01:26:39PM +0200, Ana Rey wrote:
> This process adds three new functions:
> 
> * nft_rule_expr_log_snprintf_default
> * nft_rule_expr_log_snprintf_xml
> * nft_rule_expr_log_snprintf_json

Applied this cleanup, thanks Ana.