1 files changed, 59 insertions, 0 deletions
diff --git a/utils/net.go b/utils/net.go
new file mode 100644
index 0000000..76454bd
--- /dev/null
+++ b/utils/net.go
@@ -0,0 +1,59 @@
+package utils
+
+import (
+	"fmt"
+	"strings"
+)
+
+// Mac is a 48-bit hardware address.
+type Mac struct {
+	Addr [6]byte
+}
+
+// Format renders the canonical lowercase, zero-padded form aa:bb:cc:dd:ee:ff.
+func (m *Mac) Format() string {
+	return fmt.Sprintf("%02x:%02x:%02x:%02x:%02x:%02x",
+		m.Addr[0], m.Addr[1], m.Addr[2], m.Addr[3], m.Addr[4], m.Addr[5])
+}
+
+// ParseMac reads a colon-separated hex MAC. It tolerates uppercase and the
+// zero-stripped octets macOS prints (e.g. "8:0:27:ab:cd:ef").
+func ParseMac(s string) (*Mac, error) {
+	mac := &Mac{}
+	t := strings.TrimSpace(s)
+	n, err := fmt.Sscanf(t, "%x:%x:%x:%x:%x:%x",
+		&mac.Addr[0], &mac.Addr[1], &mac.Addr[2], &mac.Addr[3], &mac.Addr[4], &mac.Addr[5])
+	if err != nil {
+		return nil, err
+	}
+	if n != 6 {
+		return nil, fmt.Errorf("invalid mac %q: parsed %d of 6 octets", s, n)
+	}
+	return mac, nil
+}
+
+// INet4 is an IPv4 address.
+type INet4 struct {
+	Addr [4]byte
+}
+
+// Format renders the dotted-decimal form a.b.c.d.
+func (n *INet4) Format() string {
+	return fmt.Sprintf("%d.%d.%d.%d", n.Addr[0], n.Addr[1], n.Addr[2], n.Addr[3])
+}
+
+// ParseINet4 reads a dotted-decimal IPv4 address. Out-of-range octets (>255)
+// overflow the byte and are rejected.
+func ParseINet4(s string) (*INet4, error) {
+	addr := &INet4{}
+	t := strings.TrimSpace(s)
+	n, err := fmt.Sscanf(t, "%d.%d.%d.%d",
+		&addr.Addr[0], &addr.Addr[1], &addr.Addr[2], &addr.Addr[3])
+	if err != nil {
+		return nil, err
+	}
+	if n != 4 {
+		return nil, fmt.Errorf("invalid ipv4 %q: parsed %d of 4 octets", s, n)
+	}
+	return addr, nil
+}