add dhcp failing test

internal/prand.go

@@ -0,0 +1,19 @@
+package internal
+
+// Prand16 generates a pseudo random number from a seed.
+func Prand16(seed uint16) uint16 {
+	// 16bit Xorshift  https://en.wikipedia.org/wiki/Xorshift
+	seed ^= seed << 7
+	seed ^= seed >> 9
+	seed ^= seed << 8
+	return seed
+}
+
+// Prand32 generates a pseudo random number from a seed.
+func Prand32[T ~uint32](seed T) T {
+	/* Algorithm "xor" from p. 4 of Marsaglia, "Xorshift RNGs" */
+	seed ^= seed << 13
+	seed ^= seed >> 17
+	seed ^= seed << 5
+	return seed
+}