+/// Represents a hostname for serialization purposes.
+/// Only the character set and length will be validated.
+/// The character set consists of ASCII alphanumeric characters, hyphens, and periods.
+/// Its length is guaranteed to be representable by a single byte.
+/// This serialization is used by BOLT 7 hostnames.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct Hostname(String);
+impl Hostname {
+ /// Returns the length of the hostname.
+ pub fn len(&self) -> u8 {
+ (&self.0).len() as u8
+ }
+}
+impl Deref for Hostname {
+ type Target = String;
+
+ fn deref(&self) -> &Self::Target {
+ &self.0
+ }
+}
+impl From<Hostname> for String {
+ fn from(hostname: Hostname) -> Self {
+ hostname.0
+ }
+}
+impl TryFrom<Vec<u8>> for Hostname {
+ type Error = ();
+
+ fn try_from(bytes: Vec<u8>) -> Result<Self, Self::Error> {
+ if let Ok(s) = String::from_utf8(bytes) {
+ Hostname::try_from(s)
+ } else {
+ Err(())
+ }
+ }
+}
+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 == '-'
+ ) {
+ Ok(Hostname(s))
+ } else {
+ Err(())
+ }
+ }
+}
+impl Writeable for Hostname {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ self.len().write(w)?;
+ w.write_all(self.as_bytes())
+ }
+}
+impl Readable for Hostname {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Hostname, DecodeError> {
+ let len: u8 = Readable::read(r)?;
+ let mut vec = Vec::with_capacity(len.into());
+ vec.resize(len.into(), 0);
+ r.read_exact(&mut vec)?;
+ Hostname::try_from(vec).map_err(|_| DecodeError::InvalidValue)
+ }
+}
+