Fix the large majority of clippy warnings

This commit fixes most of the remaining clippy warnings in the codebase.
These warnings were the more semantically difficult ones to fix.
There are some warnings that remain from the rebase that will be fixed
in the upcoming PR.

Author: Jontified

Diff for: android/translations-converter/src/android/string_value.rs

@@ -84,13 +84,6 @@ impl StringValue {
     }
 }
 
-impl StringValue {
-    /// Clones the internal string value.
-    pub fn to_string(&self) -> String {
-        self.0.clone()
-    }
-}
-
 impl Deref for StringValue {
     type Target = str;
 

Diff for: clippy.toml

@@ -0,0 +1 @@
+enum-variant-size-threshold = 1000

Diff for: mullvad-api/src/address_cache.rs

@@ -10,19 +10,16 @@ use tokio::{
 #[error(no_from)]
 pub enum Error {
     #[error(display = "Failed to open the address cache file")]
-    OpenAddressCache(#[error(source)] io::Error),
+    Open(#[error(source)] io::Error),
 
     #[error(display = "Failed to read the address cache file")]
-    ReadAddressCache(#[error(source)] io::Error),
+    Read(#[error(source)] io::Error),
 
     #[error(display = "Failed to parse the address cache file")]
-    ParseAddressCache,
+    Parse,
 
     #[error(display = "Failed to update the address cache file")]
-    WriteAddressCache(#[error(source)] io::Error),
-
-    #[error(display = "The address cache is empty")]
-    EmptyAddressCache,
+    Write(#[error(source)] io::Error),
 }
 
 #[derive(Clone)]
@@ -68,7 +65,7 @@ impl AddressCache {
         self.inner.lock().await.address
     }
 
-    pub async fn set_address(&self, address: SocketAddr) -> io::Result<()> {
+    pub async fn set_address(&self, address: SocketAddr) -> Result<(), Error> {
         let mut inner = self.inner.lock().await;
         if address != inner.address {
             self.save_to_disk(&address).await?;
@@ -77,17 +74,21 @@ impl AddressCache {
         Ok(())
     }
 
-    async fn save_to_disk(&self, address: &SocketAddr) -> io::Result<()> {
+    async fn save_to_disk(&self, address: &SocketAddr) -> Result<(), Error> {
         let write_path = match self.write_path.as_ref() {
             Some(write_path) => write_path,
             None => return Ok(()),
         };
 
-        let mut file = crate::fs::AtomicFile::new(write_path.to_path_buf()).await?;
+        let mut file = crate::fs::AtomicFile::new(write_path.to_path_buf())
+            .await
+            .map_err(Error::Open)?;
         let mut contents = address.to_string();
         contents += "\n";
-        file.write_all(contents.as_bytes()).await?;
-        file.finalize().await
+        file.write_all(contents.as_bytes())
+            .await
+            .map_err(Error::Write)?;
+        file.finalize().await.map_err(Error::Write)
     }
 }
 
@@ -103,12 +104,10 @@ impl AddressCacheInner {
 }
 
 async fn read_address_file(path: &Path) -> Result<SocketAddr, Error> {
-    let mut file = fs::File::open(path)
-        .await
-        .map_err(Error::OpenAddressCache)?;
+    let mut file = fs::File::open(path).await.map_err(Error::Open)?;
     let mut address = String::new();
     file.read_to_string(&mut address)
         .await
-        .map_err(Error::ReadAddressCache)?;
-    address.trim().parse().map_err(|_| Error::ParseAddressCache)
+        .map_err(Error::Read)?;
+    address.trim().parse().map_err(|_| Error::Parse)
 }

Diff for: mullvad-api/src/https_client_with_sni.rs

@@ -304,7 +304,7 @@ impl Service<Uri> for HttpsConnectorWithSni {
                             )
                             .await?;
                             let tls_stream = TlsStream::connect_https(socket, &hostname).await?;
-                            Ok::<_, io::Error>(ApiConnection::Direct(tls_stream))
+                            Ok::<_, io::Error>(ApiConnection::Direct(Box::new(tls_stream)))
                         }
                         InnerConnectionMode::Proxied(proxy_config) => {
                             let socket = Self::open_socket(
@@ -320,7 +320,7 @@ impl Service<Uri> for HttpsConnectorWithSni {
                                 addr,
                             );
                             let tls_stream = TlsStream::connect_https(proxy, &hostname).await?;
-                            Ok(ApiConnection::Proxied(tls_stream))
+                            Ok(ApiConnection::Proxied(Box::new(tls_stream)))
                         }
                     }
                 };

Diff for: mullvad-api/src/lib.rs

@@ -236,7 +236,7 @@ impl Runtime {
         new_address_callback: impl ApiEndpointUpdateCallback + Send + Sync + 'static,
         #[cfg(target_os = "android")] socket_bypass_tx: Option<mpsc::Sender<SocketBypassRequest>>,
     ) -> rest::RequestServiceHandle {
-        let service_handle = rest::RequestService::new(
+        let service_handle = rest::RequestService::spawn(
             sni_hostname,
             self.api_availability.handle(),
             self.address_cache.clone(),

Diff for: mullvad-api/src/proxy.rs

@@ -132,8 +132,8 @@ impl ApiConnectionMode {
 
 /// Stream that is either a regular TLS stream or TLS via shadowsocks
 pub enum ApiConnection {
-    Direct(TlsStream<TcpStream>),
-    Proxied(TlsStream<ProxyClientStream<TcpStream>>),
+    Direct(Box<TlsStream<TcpStream>>),
+    Proxied(Box<TlsStream<ProxyClientStream<TcpStream>>>),
 }
 
 impl AsyncRead for ApiConnection {

Diff for: mullvad-api/src/relay_list.rs

@@ -130,7 +130,7 @@ impl ServerRelayList {
     ) {
         let openvpn_endpoint_data = openvpn.ports;
         for mut openvpn_relay in openvpn.relays.into_iter() {
-            openvpn_relay.to_lower();
+            openvpn_relay.convert_to_lowercase();
             if let Some((country_code, city_code)) = split_location_code(&openvpn_relay.location) {
                 if let Some(country) = countries.get_mut(country_code) {
                     if let Some(city) = country
@@ -184,7 +184,7 @@ impl ServerRelayList {
             };
 
         for mut wireguard_relay in relays {
-            wireguard_relay.relay.to_lower();
+            wireguard_relay.relay.convert_to_lowercase();
             if let Some((country_code, city_code)) =
                 split_location_code(&wireguard_relay.relay.location)
             {
@@ -235,7 +235,7 @@ impl ServerRelayList {
         } = bridges;
 
         for mut bridge_relay in relays {
-            bridge_relay.to_lower();
+            bridge_relay.convert_to_lowercase();
             if let Some((country_code, city_code)) = split_location_code(&bridge_relay.location) {
                 if let Some(country) = countries.get_mut(country_code) {
                     if let Some(city) = country
@@ -345,7 +345,7 @@ struct Relay {
 }
 
 impl Relay {
-    fn to_lower(&mut self) {
+    fn convert_to_lowercase(&mut self) {
         self.hostname = self.hostname.to_lowercase();
         self.location = self.location.to_lowercase();
     }

Diff for: mullvad-api/src/rest.rs

@@ -130,7 +130,7 @@ impl<
     > RequestService<T, F>
 {
     /// Constructs a new request service.
-    pub async fn new(
+    pub async fn spawn(
         sni_hostname: Option<String>,
         api_availability: ApiAvailabilityHandle,
         address_cache: AddressCache,

Diff for: mullvad-daemon/src/cleanup.rs

@@ -7,26 +7,26 @@ use tokio::{fs, io};
 #[error(no_from)]
 pub enum Error {
     #[error(display = "Failed to get path")]
-    PathError(#[error(source)] mullvad_paths::Error),
+    Path(#[error(source)] mullvad_paths::Error),
 
     #[error(display = "Failed to remove directory {}", _0)]
-    RemoveDirError(String, #[error(source)] io::Error),
+    RemoveDir(String, #[error(source)] io::Error),
 
     #[cfg(not(target_os = "windows"))]
     #[error(display = "Failed to create directory {}", _0)]
-    CreateDirError(String, #[error(source)] io::Error),
+    CreateDir(String, #[error(source)] io::Error),
 
     #[cfg(target_os = "windows")]
     #[error(display = "Failed to get file type info")]
-    FileTypeError(#[error(source)] io::Error),
+    FileType(#[error(source)] io::Error),
 
     #[cfg(target_os = "windows")]
     #[error(display = "Failed to get dir entry")]
-    FileEntryError(#[error(source)] io::Error),
+    FileEntry(#[error(source)] io::Error),
 
     #[cfg(target_os = "windows")]
     #[error(display = "Failed to read dir entries")]
-    ReadDirError(#[error(source)] io::Error),
+    ReadDir(#[error(source)] io::Error),
 }
 
 pub async fn clear_directories() -> Result<(), Error> {
@@ -35,12 +35,12 @@ pub async fn clear_directories() -> Result<(), Error> {
 }
 
 async fn clear_log_directory() -> Result<(), Error> {
-    let log_dir = mullvad_paths::get_log_dir().map_err(Error::PathError)?;
+    let log_dir = mullvad_paths::get_log_dir().map_err(Error::Path)?;
     clear_directory(&log_dir).await
 }
 
 async fn clear_cache_directory() -> Result<(), Error> {
-    let cache_dir = mullvad_paths::cache_dir().map_err(Error::PathError)?;
+    let cache_dir = mullvad_paths::cache_dir().map_err(Error::Path)?;
     clear_directory(&cache_dir).await
 }
 
@@ -49,22 +49,22 @@ async fn clear_directory(path: &Path) -> Result<(), Error> {
     {
         fs::remove_dir_all(path)
             .await
-            .map_err(|e| Error::RemoveDirError(path.display().to_string(), e))?;
+            .map_err(|e| Error::RemoveDir(path.display().to_string(), e))?;
         fs::create_dir_all(path)
             .await
-            .map_err(|e| Error::CreateDirError(path.display().to_string(), e))
+            .map_err(|e| Error::CreateDir(path.display().to_string(), e))
     }
     #[cfg(target_os = "windows")]
     {
-        let mut dir = fs::read_dir(&path).await.map_err(Error::ReadDirError)?;
+        let mut dir = fs::read_dir(&path).await.map_err(Error::ReadDir)?;
 
         let mut result = Ok(());
 
-        while let Some(entry) = dir.next_entry().await.map_err(Error::FileEntryError)? {
+        while let Some(entry) = dir.next_entry().await.map_err(Error::FileEntry)? {
             let entry_type = match entry.file_type().await {
                 Ok(entry_type) => entry_type,
                 Err(error) => {
-                    result = result.and(Err(Error::FileTypeError(error)));
+                    result = result.and(Err(Error::FileType(error)));
                     continue;
                 }
             };
@@ -74,9 +74,8 @@ async fn clear_directory(path: &Path) -> Result<(), Error> {
             } else {
                 fs::remove_dir_all(entry.path()).await
             };
-            result = result.and(
-                removal.map_err(|e| Error::RemoveDirError(entry.path().display().to_string(), e)),
-            );
+            result = result
+                .and(removal.map_err(|e| Error::RemoveDir(entry.path().display().to_string(), e)));
         }
         result
     }

Diff for: mullvad-daemon/src/device/api.rs

@@ -35,10 +35,10 @@ impl CurrentApiCall {
     }
 
     pub fn is_validating(&self) -> bool {
-        match &self.current_call {
-            Some(Call::Validation(_)) | Some(Call::OneshotKeyRotation(_)) => true,
-            _ => false,
-        }
+        matches!(
+            &self.current_call,
+            Some(Call::Validation(_)) | Some(Call::OneshotKeyRotation(_))
+        )
     }
 
     pub fn is_running_timed_totation(&self) -> bool {
@@ -51,10 +51,7 @@ impl CurrentApiCall {
 
     pub fn is_logging_in(&self) -> bool {
         use Call::*;
-        match &self.current_call {
-            Some(Login(..)) => true,
-            _ => false,
-        }
+        matches!(&self.current_call, Some(Login(..)))
     }
 }
 

Diff for: mullvad-daemon/src/exception_logging/unix.rs

@@ -5,7 +5,7 @@ use nix::sys::signal::{sigaction, SaFlags, SigAction, SigHandler, SigSet, Signal
 
 use std::{convert::TryFrom, sync::Once};
 
-const INIT_ONCE: Once = Once::new();
+static INIT_ONCE: Once = Once::new();
 
 const FAULT_SIGNALS: [Signal; 5] = [
     // Access to invalid memory address