1 files changed, 23 insertions, 0 deletions
diff --git a/validate.c b/validate.c
new file mode 100644
index 0000000..49005f0
--- /dev/null
+++ b/validate.c
@@ -0,0 +1,23 @@
+//
+// Created by Keuin on 2021/12/30.
+//
+
+#include "validate.h"
+#include <stdio.h>
+
+/**
+ * Check if a given string is a valid dot-decimal representation of an IPv4 address.
+ * @param s the string.
+ * @return Non-zero if true, zero if false.
+ */
+int is_valid_ipv4(const char *s) {
+    // TODO buggy
+//    unsigned int addr[4];
+//    if (sscanf(s, "%ud.%ud.%ud.%ud", &addr[0], &addr[1], &addr[2], &addr[3]) != 4)
+//        return 0;
+//    for (int i = 0; i < 4; ++i) {
+//        if (addr[i] > 255) return 0;
+//        if (addr[i] == 0 && (i == 0 || i == 3)) return 0;
+//    }
+    return 1;
+}