1 files changed, 35 insertions, 0 deletions
diff --git a/internal/util/util.go b/internal/util/util.go
new file mode 100644
index 0000000..252815e
--- /dev/null
+++ b/internal/util/util.go
@@ -0,0 +1,35 @@
+package util
+
+import (
+	"math/rand" // not crypto secure
+	"regexp"
+)
+
+const randHostnameCharset = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-"
+const randStringCharset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+
+var (
+	// Up to 15 characters; only letters, digits, and hyphens (with hyphens not at the start or end).
+	randHostnameRegex = regexp.MustCompile(`^[a-zA-Z][a-zA-Z0-9-]{0,14}[a-zA-Z0-9]$`)
+)
+
+func RandomHostname() (hostname string) {
+	for {
+		// between 2 and 10 characters
+		if hostname = RandomStringFromCharset(randHostnameCharset, rand.Intn(8)+2); randHostnameRegex.MatchString(hostname) {
+			return
+		}
+	}
+}
+
+func RandomString() string {
+	return RandomStringFromCharset(randStringCharset, rand.Intn(10)+6)
+}
+
+func RandomStringFromCharset(charset string, length int) string {
+	b := make([]byte, length)
+	for i := range length {
+		b[i] = charset[rand.Intn(len(charset))]
+	}
+	return string(b)
+}