rust: Refactor protover::is_supported_here().

This changes `protover::is_supported_here()` to be aware of new datatypes
(e.g. don't call `.0` on things which are no longer tuple structs) and also
changes the method signature to take borrows, making it faster, threadable, and
easier to read (i.e. the caller can know from reading the function signature
that the function won't mutate values passed into it).

 * CHANGE the `protover::is_supported_here()` function to take borrows.
 * REFACTOR the `protover::is_supported_here()` function to be aware of new
   datatypes.
 * FIXES part of #24031: https://bugs.torproject.org/24031

src/rust/protover/protover.rs

@@ -579,26 +579,25 @@ impl ProtoverVote {
 ///
 /// # Examples
 /// ```
-/// use protover::*;
+/// use protover::is_supported_here;
+/// use protover::Protocol;
 ///
-/// let is_supported = is_supported_here(Proto::Link, 10);
+/// let is_supported = is_supported_here(&Protocol::Link, &10);
 /// assert_eq!(false, is_supported);
 ///
-/// let is_supported = is_supported_here(Proto::Link, 1);
+/// let is_supported = is_supported_here(&Protocol::Link, &1);
 /// assert_eq!(true, is_supported);
 /// ```
-pub fn is_supported_here(proto: Proto, vers: Version) -> bool {
-    let currently_supported = match SupportedProtocols::tor_supported() {
-        Ok(result) => result.0,
+pub fn is_supported_here(proto: &Protocol, vers: &Version) -> bool {
+    let currently_supported: ProtoEntry = match ProtoEntry::supported() {
+        Ok(result) => result,
         Err(_) => return false,
     };
-
-    let supported_versions = match currently_supported.get(&proto) {
+    let supported_versions = match currently_supported.get(proto) {
         Some(n) => n,
         None => return false,
     };
-
-    supported_versions.0.contains(&vers)
+    supported_versions.contains(vers)
 }
 
 /// Older versions of Tor cannot infer their own subprotocols