yparser: improve address type detection

src/libknot/yparser/yptrafo.c

@@ -14,6 +14,7 @@
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+#include <ctype.h>
 #include <stdlib.h>
 #include <inttypes.h>
 #include <arpa/inet.h>
@@ -293,6 +294,31 @@ static int yp_int_to_txt(
 	return KNOT_EOK;
 }
 
+static uint8_t sock_type_guess(
+	char const *txt,
+	size_t txt_len)
+{
+	size_t dots = 0;
+	size_t semicolons = 0;
+	size_t digits = 0;
+
+	// Analyze the string.
+	for (size_t i = 0; i < txt_len; i++) {
+		if (txt[i] == '.') dots++;
+		else if (txt[i] == ':') semicolons++;
+		else if (isdigit((int)txt[i]) != 0) digits++;
+	}
+
+	// Guess socket type.
+	if (semicolons >= 1) {
+		return 6;
+	} else if (semicolons == 0 && dots == 3 && digits >= 3) {
+		return 4;
+	} else {
+		return 0;
+	}
+}
+
 static int addr_to_bin(
 	TXT_BIN_PARAMS,
 	bool allow_unix)
@@ -300,20 +326,18 @@ static int addr_to_bin(
 	struct in_addr  addr4;
 	struct in6_addr addr6;
 
-	uint8_t type;
+	uint8_t type = sock_type_guess(txt, txt_len);
+
 	size_t addr_len;
 	const void *addr;
 
-	if (inet_pton(AF_INET, txt, &addr4) == 1) {
-		type = 4;
+	if (type == 4 && inet_pton(AF_INET, txt, &addr4) == 1) {
 		addr_len = sizeof(addr4.s_addr);
 		addr = &(addr4.s_addr);
-	} else if (inet_pton(AF_INET6, txt, &addr6) == 1) {
-		type = 6;
+	} else if (type == 6 && inet_pton(AF_INET6, txt, &addr6) == 1) {
 		addr_len = sizeof(addr6.s6_addr);
 		addr = &(addr6.s6_addr);
-	} else if (allow_unix && txt_len > 0) {
-		type = 0;
+	} else if (type == 0 && allow_unix && txt_len > 0) {
 		addr_len = txt_len + 1; // + trailing zero.
 		addr = txt;
 	} else {