adds avahi base service to init function of mdns controller (#407)

* adds avahi base service to init function of mdns controller

* Apply suggestions from code review

* adds hostname set to startup sequence

* Apply suggestions from code review

Co-authored-by: Aiden McClelland <3732071+dr-bonez@users.noreply.github.com>

appmgr/src/hostname.rs

@@ -0,0 +1,36 @@
+use digest::Digest;
+use tokio::process::Command;
+
+use crate::util::Invoke;
+use crate::{Error, ErrorKind};
+
+pub async fn get_hostname() -> Result<String, Error> {
+    let out = Command::new("hostname")
+        .invoke(ErrorKind::ParseSysInfo)
+        .await?;
+    let out_string = String::from_utf8(out)?;
+    Ok(out_string.trim().to_owned())
+}
+
+pub async fn set_hostname(hostname: &str) -> Result<(), Error> {
+    let _out = Command::new("hostnamectl")
+        .arg("set-hostname")
+        .arg(hostname)
+        .invoke(ErrorKind::ParseSysInfo)
+        .await?;
+    Ok(())
+}
+
+pub async fn get_product_key() -> Result<String, Error> {
+    let out = tokio::fs::read_to_string("/boot/product_key.txt").await?;
+    Ok(out.trim().to_owned())
+}
+
+pub async fn sync_hostname() -> Result<(), Error> {
+    let key = get_product_key().await?;
+    let mut hasher = sha2::Sha256::new();
+    hasher.update(key.as_bytes());
+    let res = hasher.finalize();
+    set_hostname(&format!("start9-{}", hex::encode(&res[0..4]))).await?;
+    Ok(())
+}