[PATCH lnf-ct] conntrack: api: add nfct_snprintf_labels

[Florian Westphal <fw@strlen.de>]

nfct_snprintf doesn't print connlabels, as they're system specific
and can easily generate lots of output.

This adds a new helper function, nfct_snprintf_labels, to print the mapped
label names to a buffer.  Input is a bitmask to test, and a map
describing the names of the individual bits.

Those names whose bits are contained in the bitset are then
written to the buffer.

output looks like this:
eth0-in,eth1-in

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 I added an 'output_type' argument, not sure if this is useful.
 [ I don't see why NFCT_O_XML would be useful here, OTOH
   adding the output_type argument would allow to add it later ]

 include/internal/prototypes.h                      |  2 +
 .../libnetfilter_conntrack.h                       |  4 ++
 src/conntrack/api.c                                | 16 ++++++++
 src/conntrack/labels.c                             | 44 ++++++++++++++++++++++
 4 files changed, 66 insertions(+)

diff --git a/include/internal/prototypes.h b/include/internal/prototypes.h
index 484deea..dded472 100644
--- a/include/internal/prototypes.h
+++ b/include/internal/prototypes.h
@@ -62,5 +62,7 @@ void __labelmap_destroy(struct nfct_labelmap *);
 
 int __labelmap_get_bit(struct nfct_labelmap *map, const char *name);
 const char *__labelmap_get_name(struct nfct_labelmap *map, unsigned int bit);
+int __labels_snprintf(char *buf, unsigned int len, struct nfct_labelmap *map,
+			const struct nfct_bitmask *b, unsigned int out_type);
 
 #endif
diff --git a/include/libnetfilter_conntrack/libnetfilter_conntrack.h b/include/libnetfilter_conntrack/libnetfilter_conntrack.h
index 39dc24c..3dafe46 100644
--- a/include/libnetfilter_conntrack/libnetfilter_conntrack.h
+++ b/include/libnetfilter_conntrack/libnetfilter_conntrack.h
@@ -294,6 +294,10 @@ struct nfct_labelmap *nfct_labelmap_new(const char *mapfile);
 void nfct_labelmap_destroy(struct nfct_labelmap *map);
 const char *nfct_labelmap_get_name(struct nfct_labelmap *m, unsigned int bit);
 int nfct_labelmap_get_bit(struct nfct_labelmap *m, const char *name);
+int nfct_snprintf_labels(char *buf, unsigned int len,
+			 struct nfct_labelmap *labelmap,
+			 const struct nfct_bitmask *b,
+			 unsigned int out_type);
 
 /* setter */
 extern void nfct_set_attr(struct nf_conntrack *ct,
diff --git a/src/conntrack/api.c b/src/conntrack/api.c
index b6c453f..0a668ce 100644
--- a/src/conntrack/api.c
+++ b/src/conntrack/api.c
@@ -1523,6 +1523,22 @@ int nfct_labelmap_get_bit(struct nfct_labelmap *m, const char *name)
 }
 
 /**
+ * nfct_snprintf_labels - print a bitmask object to a buffer
+ * \param buf buffer used to build the names of the bitmask
+ * \param len size of the buffer
+ * \param map nfct_labelmap which maps the bit values to the desired strings
+ * \param b pointer to a valid bitmask object
+ * \param output_type print type (NFCT_O_DEFAULT only at this time)
+ */
+int nfct_snprintf_labels(char *buf, unsigned int len,
+			 struct nfct_labelmap *map,
+			 const struct nfct_bitmask *b,
+			 unsigned int out_type)
+{
+	return __labels_snprintf(buf, len, map, b, out_type);
+}
+
+/**
  * nfct_labelmap_new - create a new label map
  *
  * \param mapfile the file containing the bit <-> name mapping
diff --git a/src/conntrack/labels.c b/src/conntrack/labels.c
index 7dfb780..4511180 100644
--- a/src/conntrack/labels.c
+++ b/src/conntrack/labels.c
@@ -267,3 +267,47 @@ struct nfct_labelmap *__labelmap_new(const char *name)
 	__labelmap_destroy(map);
 	return NULL;
 }
+
+static int
+__labels_snprintf_fmt(char *buf, unsigned int len,
+		      struct nfct_labelmap *map,
+		      const struct nfct_bitmask *b,
+		      const char *fmt)
+{
+	unsigned int i, max;
+	int ret, size = 0, offset = 0;
+
+	max = nfct_bitmask_maxbit(b);
+	for (i = 0; i <= max && len; i++) {
+		const char *name;
+		if (!nfct_bitmask_test_bit(b, i))
+			continue;
+		name = nfct_labelmap_get_name(map, i);
+		if (!name || strcmp(name, "") == 0)
+			continue;
+		ret = snprintf(buf + offset, len, fmt, name);
+		BUFFER_SIZE(ret, size, len, offset);
+	}
+	return size;
+}
+
+int
+__labels_snprintf(char *buf, unsigned int len,
+		  struct nfct_labelmap *map,
+		  const struct nfct_bitmask *b, unsigned int out_type)
+{
+	int size = 0;
+
+	switch (out_type) {
+	case NFCT_O_DEFAULT:
+		size = __labels_snprintf_fmt(buf, len, map, b, "%s,");
+		if (size && size <= len)
+			buf[--size] = 0; /* strip trailing ',' */
+		break;
+	default:
+		errno = ENOENT;
+		return -1;
+	}
+
+	return size;
+}
-- 
1.8.1.5