output: SQLITE3: improve mapping of DB columns to fields

Currently, we copy the column-name to a buffer, iterate over it to
replace the underscores with full-stops, using `strchr` from the start
of the buffer on each iteration, then copy the buffer to the field's
`name` member.

Apart from the inefficiency, `strncpy` is used to do the copies, which
leads gcc to complain:

  ulogd_output_SQLITE3.c:341:17: warning: `strncpy` output may be truncated copying 31 bytes from a string of length 31

Furthermore, the buffer is not initialized, which means that there is
also a possible buffer overrun if the column-name is too long, since
`strncpy` will not append a NUL.

Instead, copy the column-name directly to the field using `snprintf`,
and run `strchr` from the last underscore on each iteration.

Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 13 insertions, 13 deletions

diff --git a/output/sqlite3/ulogd_output_SQLITE3.c b/output/sqlite3/ulogd_output_SQLITE3.c
index 692ff2b..d2857df 100644
--- a/output/sqlite3/ulogd_output_SQLITE3.c
+++ b/output/sqlite3/ulogd_output_SQLITE3.c
@@ -301,9 +301,6 @@ static int
 sqlite3_init_db(struct ulogd_pluginstance *pi)
 {
 	struct sqlite3_priv *priv = (void *)pi->private;
-	char buf[ULOGD_MAX_KEYLEN + 1];
-	char *underscore;
-	struct field *f;
 	sqlite3_stmt *schema_stmt;
 	int col, num_cols;
 
@@ -323,24 +320,27 @@ sqlite3_init_db(struct ulogd_pluginstance *pi)
 	}
 
 	for (col = 0; col < num_cols; col++) {
-		strncpy(buf, sqlite3_column_name(schema_stmt, col), ULOGD_MAX_KEYLEN);
-
-		/* replace all underscores with dots */
-		while ((underscore = strchr(buf, '_')) != NULL)
-			*underscore = '.';
-
-		DEBUGP("field '%s' found\n", buf);
+		char *underscore;
+		struct field *f;
 
 		/* prepend it to the linked list */
 		if ((f = calloc(1, sizeof(struct field))) == NULL) {
 			ulogd_log(ULOGD_ERROR, "SQLITE3: out of memory\n");
 			return -1;
 		}
-		strncpy(f->name, buf, ULOGD_MAX_KEYLEN);
+		snprintf(f->name, sizeof(f->name),
+			 "%s", sqlite3_column_name(schema_stmt, col));
+
+		/* replace all underscores with dots */
+		for (underscore = f->name;
+		     (underscore = strchr(underscore, '_')) != NULL; )
+			*underscore = '.';
+
+		DEBUGP("field '%s' found\n", f->name);
 
-		if ((f->key = ulogd_find_key(pi, buf)) == NULL) {
+		if ((f->key = ulogd_find_key(pi, f->name)) == NULL) {
 			ulogd_log(ULOGD_ERROR,
-				  "SQLITE3: unknown input key: %s\n", buf);
+				  "SQLITE3: unknown input key: %s\n", f->name);
 			free(f);
 			return -1;
 		}