f use Hostname's validation

Author: TheBlueMatt

lightning/src/onion_message/dns_resolution.rs

@@ -169,7 +169,7 @@ impl HumanReadableName {
 		if user.is_empty() || domain.is_empty() {
 			return Err(());
 		}
-		if !user.is_ascii() || !domain.is_ascii() {
+		if !Hostname::str_is_valid_hostname(&user) || !Hostname::str_is_valid_hostname(&domain) {
 			return Err(());
 		}
 		Ok(HumanReadableName { user, domain })

lightning/src/util/ser.rs

@@ -1490,6 +1490,16 @@ impl Hostname {
 	pub fn len(&self) -> u8 {
 		(&self.0).len() as u8
 	}
+
+	/// Check if the chars in `s` are allowed to be included in a [`Hostname`].
+	pub(crate) fn str_is_valid_hostname(s: &str) -> bool {
+		s.len() <= 255 &&
+		s.chars().all(|c|
+			c.is_ascii_alphanumeric() ||
+			c == '.' ||
+			c == '-'
+		)
+	}
 }
 
 impl core::fmt::Display for Hostname {
@@ -1525,11 +1535,7 @@ impl TryFrom<String> for Hostname {
 	type Error = ();
 
 	fn try_from(s: String) -> Result<Self, Self::Error> {
-		if s.len() <= 255 && s.chars().all(|c|
-			c.is_ascii_alphanumeric() ||
-			c == '.' ||
-			c == '-'
-		) {
+		if Hostname::str_is_valid_hostname(&s) {
 			Ok(Hostname(s))
 		} else {
 			Err(())