Merge branch 'eliminate-error-chain-tunnel'

12 files changed, 231 insertions, 214 deletions

diff --git a/talpid-core/src/dns/linux/static_resolv_conf.rs b/talpid-core/src/dns/linux/static_resolv_conf.rs
index 71b6973edf..73c9aa4221 100644
--- a/talpid-core/src/dns/linux/static_resolv_conf.rs
+++ b/talpid-core/src/dns/linux/static_resolv_conf.rs
@@ -1,5 +1,4 @@
 use super::RESOLV_CONF_PATH;
-use error_chain::ChainedError;
 use notify::{RecommendedWatcher, RecursiveMode, Watcher};
 use parking_lot::Mutex;
 use resolv_conf::{Config, ScopedIp};
@@ -9,27 +8,28 @@ use std::{
     sync::{mpsc, Arc},
     thread,
 };
+use talpid_types::ErrorExt;
 
 const RESOLV_CONF_BACKUP_PATH: &str = "/etc/resolv.conf.mullvadbackup";
 
-error_chain! {
-    errors {
-        WatchResolvConf {
-            description("Failed to watch /etc/resolv.conf for changes")
-        }
+pub type Result<T> = std::result::Result<T, Error>;
 
-        WriteResolvConf {
-            description("Failed to write to /etc/resolv.conf")
-        }
+#[derive(err_derive::Error, Debug)]
+pub enum Error {
+    #[error(display = "Failed to watch /etc/resolv.conf for changes")]
+    WatchResolvConf(#[error(cause)] notify::Error),
 
-        BackupResolvConf {
-            description("Failed to create backup of /etc/resolv.conf")
-        }
+    #[error(display = "Failed to write to {}", _0)]
+    WriteResolvConf(&'static str, #[error(cause)] io::Error),
 
-        RestoreResolvConf {
-            description("Failed to restore /etc/resolv.conf from backup")
-        }
-    }
+    #[error(display = "Failed to read from {}", _0)]
+    ReadResolvConf(&'static str, #[error(cause)] io::Error),
+
+    #[error(display = "resolv.conf at {} could not be parsed", _0)]
+    ParseError(&'static str, #[error(cause)] resolv_conf::ParseError),
+
+    #[error(display = "Failed to remove stale resolv.conf backup at {}", _0)]
+    RemoveBackup(&'static str, #[error(cause)] io::Error),
 }
 
 pub struct StaticResolvConf {
@@ -39,7 +39,7 @@ pub struct StaticResolvConf {
 
 impl StaticResolvConf {
     pub fn new() -> Result<Self> {
-        restore_from_backup().chain_err(|| ErrorKind::RestoreResolvConf)?;
+        restore_from_backup()?;
 
         let state = Arc::new(Mutex::new(None));
         let watcher = DnsWatcher::start(state.clone())?;
@@ -54,8 +54,8 @@ impl StaticResolvConf {
         let mut state = self.state.lock();
         let new_state = match state.take() {
             None => {
-                let backup = read_config().chain_err(|| ErrorKind::BackupResolvConf)?;
-                write_backup(&backup).chain_err(|| ErrorKind::BackupResolvConf)?;
+                let backup = read_config()?;
+                write_backup(&backup)?;
 
                 State {
                     backup,
@@ -111,11 +111,11 @@ struct DnsWatcher {
 impl DnsWatcher {
     fn start(state: Arc<Mutex<Option<State>>>) -> Result<Self> {
         let (event_tx, event_rx) = mpsc::channel();
-        let mut watcher = notify::raw_watcher(event_tx).chain_err(|| ErrorKind::WatchResolvConf)?;
+        let mut watcher = notify::raw_watcher(event_tx).map_err(Error::WatchResolvConf)?;
 
         watcher
             .watch(RESOLV_CONF_PATH, RecursiveMode::NonRecursive)
-            .chain_err(|| ErrorKind::WatchResolvConf)?;
+            .map_err(Error::WatchResolvConf)?;
 
         thread::spawn(move || Self::event_loop(event_rx, &state));
 
@@ -127,9 +127,12 @@ impl DnsWatcher {
             let mut locked_state = state.lock();
 
             if let Err(error) = Self::update(locked_state.as_mut()) {
-                let chained_error = error
-                    .chain_err(|| "Failed to update DNS state after DNS settings have changed.");
-                log::error!("{}", chained_error.display_chain());
+                log::error!(
+                    "{}",
+                    error.display_chain_with_msg(
+                        "Failed to update DNS state after DNS settings changed"
+                    )
+                );
             }
         }
     }
@@ -153,7 +156,7 @@ impl DnsWatcher {
                 new_config.nameservers.append(&mut state.backup.nameservers);
                 state.backup = new_config;
 
-                write_backup(&state.backup).chain_err(|| "Failed to update /etc/resolv.conf backup")
+                write_backup(&state.backup)
             }
         } else {
             Ok(())
@@ -162,22 +165,21 @@ impl DnsWatcher {
 }
 
 fn read_config() -> Result<Config> {
-    let contents =
-        fs::read_to_string(RESOLV_CONF_PATH).chain_err(|| "Failed to read /etc/resolv.conf")?;
-    let config =
-        Config::parse(&contents).chain_err(|| "Failed to parse contents of /etc/resolv.conf")?;
+    let contents = fs::read_to_string(RESOLV_CONF_PATH)
+        .map_err(|e| Error::ReadResolvConf(RESOLV_CONF_PATH, e))?;
+    let config = Config::parse(&contents).map_err(|e| Error::ParseError(RESOLV_CONF_PATH, e))?;
 
     Ok(config)
 }
 
 fn write_config(config: &Config) -> Result<()> {
     fs::write(RESOLV_CONF_PATH, config.to_string().as_bytes())
-        .chain_err(|| ErrorKind::WriteResolvConf)
+        .map_err(|e| Error::WriteResolvConf(RESOLV_CONF_PATH, e))
 }
 
 fn write_backup(backup: &Config) -> Result<()> {
     fs::write(RESOLV_CONF_BACKUP_PATH, backup.to_string().as_bytes())
-        .chain_err(|| "Failed to write to /etc/resolv.conf backup file")
+        .map_err(|e| Error::WriteResolvConf(RESOLV_CONF_BACKUP_PATH, e))
 }
 
 fn restore_from_backup() -> Result<()> {
@@ -185,20 +187,17 @@ fn restore_from_backup() -> Result<()> {
         Ok(backup) => {
             log::info!("Restoring DNS state from backup");
             let config = Config::parse(&backup)
-                .chain_err(|| "Backup of /etc/resolv.conf could not be parsed")?;
+                .map_err(|e| Error::ParseError(RESOLV_CONF_BACKUP_PATH, e))?;
 
             write_config(&config)?;
 
             fs::remove_file(RESOLV_CONF_BACKUP_PATH)
-                .chain_err(|| "Failed to remove stale backup of /etc/resolv.conf")
+                .map_err(|e| Error::RemoveBackup(RESOLV_CONF_BACKUP_PATH, e))
         }
         Err(ref error) if error.kind() == io::ErrorKind::NotFound => {
             log::debug!("No DNS state backup to restore");
             Ok(())
         }
-        Err(error) => Err(Error::with_chain(
-            error,
-            "Failed to read /etc/resolv.conf backup",
-        )),
+        Err(error) => Err(Error::ReadResolvConf(RESOLV_CONF_BACKUP_PATH, error)),
     }
 }
diff --git a/talpid-core/src/firewall/linux.rs b/talpid-core/src/firewall/linux.rs
index 5c8d9e777e..540bdff1ee 100644
--- a/talpid-core/src/firewall/linux.rs
+++ b/talpid-core/src/firewall/linux.rs
@@ -164,7 +164,7 @@ impl Firewall {
                     "Expected '{}' netfilter table to be set, but it is not",
                     expected_table.to_string_lossy()
                 );
-                bail!(Error::NetfilterTableNotSetError)
+                return Err(Error::NetfilterTableNotSetError);
             }
         }
         Ok(())
diff --git a/talpid-core/src/lib.rs b/talpid-core/src/lib.rs
index 1499557439..3b2bac9529 100644
--- a/talpid-core/src/lib.rs
+++ b/talpid-core/src/lib.rs
@@ -11,9 +11,6 @@
 //! GNU General Public License as published by the Free Software Foundation, either version 3 of
 //! the License, or (at your option) any later version.
 
-#[macro_use]
-extern crate error_chain;
-
 /// Misc FFI utilities.
 #[cfg(windows)]
 #[macro_use]
diff --git a/talpid-core/src/routing/android.rs b/talpid-core/src/routing/android.rs
index fa5c5c8f8e..5c562537f1 100644
--- a/talpid-core/src/routing/android.rs
+++ b/talpid-core/src/routing/android.rs
@@ -7,7 +7,10 @@ use std::{
     net::{IpAddr, Ipv4Addr},
 };
 
-error_chain! {}
+/// Stub error type for routing errors on Android.
+#[derive(Debug, err_derive::Error)]
+#[error(display = "Unknown Android routing error")]
+pub struct Error;
 
 pub struct RouteManager;
 
@@ -18,15 +21,15 @@ impl super::RoutingT for RouteManager {
         Ok(RouteManager)
     }
 
-    fn add_routes(&mut self, _required_routes: RequiredRoutes) -> Result<()> {
+    fn add_routes(&mut self, _required_routes: RequiredRoutes) -> Result<(), Self::Error> {
         Ok(())
     }
 
-    fn delete_routes(&mut self) -> Result<()> {
+    fn delete_routes(&mut self) -> Result<(), Self::Error> {
         Ok(())
     }
 
-    fn get_default_route_node(&mut self) -> Result<IpAddr> {
+    fn get_default_route_node(&mut self) -> Result<IpAddr, Self::Error> {
         Ok(IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)))
     }
 }
diff --git a/talpid-core/src/routing/linux.rs b/talpid-core/src/routing/linux.rs
index 73de509a0e..b229b192c2 100644
--- a/talpid-core/src/routing/linux.rs
+++ b/talpid-core/src/routing/linux.rs
@@ -9,20 +9,26 @@ use std::{
 
 pub type Result<T> = std::result::Result<T, Error>;
 
+/// Errors that can happen in the Linux routing integration
 #[derive(err_derive::Error, Debug)]
 pub enum Error {
+    /// Failed to add route.
     #[error(display = "Failed to add route")]
     FailedToAddRoute(#[error(cause)] io::Error),
 
+    /// Failed to remove route.
     #[error(display = "Failed to remove route")]
     FailedToRemoveRoute(#[error(cause)] io::Error),
 
+    /// Error while running "ip route".
     #[error(display = "Error while running \"ip route\"")]
     FailedToRunIp(#[error(cause)] io::Error),
 
+    /// No default route in "ip route" output.
     #[error(display = "No default route in \"ip route\" output")]
     NoDefaultRoute,
 
+    /// Failed to parse default route as IP.
     #[error(display = "Failed to parse default route as IP: {}", _0)]
     ParseDefaultRoute(String, #[error(cause)] AddrParseError),
 }
diff --git a/talpid-core/src/routing/macos.rs b/talpid-core/src/routing/macos.rs
index d0e9497c1c..722efbb320 100644
--- a/talpid-core/src/routing/macos.rs
+++ b/talpid-core/src/routing/macos.rs
@@ -10,20 +10,26 @@ use std::{
 
 pub type Result<T> = std::result::Result<T, Error>;
 
+/// Errors that can happen in the macOS routing integration.
 #[derive(err_derive::Error, Debug)]
 pub enum Error {
+    /// Failed to add route.
     #[error(display = "Failed to add route")]
     FailedToAddRoute(#[error(cause)] io::Error),
 
+    /// Failed to remove route.
     #[error(display = "Failed to remove route")]
     FailedToRemoveRoute(#[error(cause)] io::Error),
 
+    /// Error while running "ip route".
     #[error(display = "Error while running \"ip route\"")]
     FailedToRunIp(#[error(cause)] io::Error),
 
+    /// No default route in "ip route" output.
     #[error(display = "No default route in \"ip route\" output")]
     NoDefaultRoute,
 
+    /// Failed to parse default route as IP.
     #[error(display = "Failed to parse default route as IP: {}", _0)]
     ParseDefaultRoute(String, #[error(cause)] AddrParseError),
 }
diff --git a/talpid-core/src/routing/mod.rs b/talpid-core/src/routing/mod.rs
index 612c0b2396..b2e299553f 100644
--- a/talpid-core/src/routing/mod.rs
+++ b/talpid-core/src/routing/mod.rs
@@ -13,6 +13,8 @@ mod imp;
 #[path = "android.rs"]
 mod imp;
 
+pub use self::imp::Error;
+
 mod subprocess;
 
 /// A single route
@@ -53,24 +55,24 @@ pub struct RouteManager {
 
 impl RouteManager {
     /// Creates a new RouteManager.
-    pub fn new() -> Result<Self, imp::Error> {
+    pub fn new() -> Result<Self, Error> {
         Ok(RouteManager {
             inner: imp::RouteManager::new()?,
         })
     }
 
     /// Set routes in the routing table.
-    pub fn add_routes(&mut self, required_routes: RequiredRoutes) -> Result<(), imp::Error> {
+    pub fn add_routes(&mut self, required_routes: RequiredRoutes) -> Result<(), Error> {
         self.inner.add_routes(required_routes)
     }
 
     /// Remove previously set routes from the routing table.
-    pub fn delete_routes(&mut self) -> Result<(), imp::Error> {
+    pub fn delete_routes(&mut self) -> Result<(), Error> {
         self.inner.delete_routes()
     }
 
     /// Retrieves the gateway for the default route.
-    pub fn get_default_route_node(&mut self) -> Result<std::net::IpAddr, imp::Error> {
+    pub fn get_default_route_node(&mut self) -> Result<std::net::IpAddr, Error> {
         // use routing::RoutingT;
         self.inner.get_default_route_node()
     }
@@ -87,7 +89,7 @@ impl Drop for RouteManager {
 /// This trait unifies platform specific implementations of route managers
 pub trait RoutingT: Sized {
     /// Error type of the implementation
-    type Error: ::std::error::Error;
+    type Error: std::error::Error;
 
     /// Creates a new router
     fn new() -> Result<Self, Self::Error>;
diff --git a/talpid-core/src/tunnel/mod.rs b/talpid-core/src/tunnel/mod.rs
index 04332908c4..987f80c872 100644
--- a/talpid-core/src/tunnel/mod.rs
+++ b/talpid-core/src/tunnel/mod.rs
@@ -19,36 +19,37 @@ pub mod wireguard;
 const OPENVPN_LOG_FILENAME: &str = "openvpn.log";
 const WIREGUARD_LOG_FILENAME: &str = "wireguard.log";
 
+/// Results from operations in the tunnel module.
+pub type Result<T> = std::result::Result<T, Error>;
 
-error_chain! {
-    errors {
-        /// Tunnel can't have IPv6 enabled because the system has disabled IPv6 support.
-        EnableIpv6Error {
-            description("Can't enable IPv6 on tunnel interface because IPv6 is disabled")
-        }
-        /// Running on an operating system which is not supported yet.
-        UnsupportedPlatform {
-            description("Tunnel type not supported on this operating system")
-        }
-        /// Failed to rotate tunnel log file
-        RotateLogError {
-            description("Failed to rotate tunnel log file")
-        }
-        /// Failure to build Wireguard configuration.
-        WireguardConfigError {
-            description("Failed to configure Wireguard with the given parameters")
-        }
-    }
+/// Errors that can occur in the [`TunnelMonitor`].
+#[derive(err_derive::Error, Debug, derive_more::From)]
+pub enum Error {
+    /// Tunnel can't have IPv6 enabled because the system has disabled IPv6 support.
+    #[error(display = "Can't enable IPv6 on tunnel interface because IPv6 is disabled")]
+    EnableIpv6Error,
 
-    links {
-        OpenVpnTunnelMonitoringError(openvpn::Error, openvpn::ErrorKind)
-        /// There was an error listening for events from the OpenVPN tunnel
-        ;
-        WirguardTunnelMonitoringError(wireguard::Error, wireguard::ErrorKind)
-        /// There was an error listening for events from the OpenVPN tunnel
-        #[cfg(any(target_os = "linux", target_os = "macos"))]
-        ;
-    }
+    /// Running on an operating system which is not supported yet.
+    #[error(display = "Tunnel type not supported on this operating system")]
+    UnsupportedPlatform,
+
+    /// Failed to rotate tunnel log file
+    #[error(display = "Failed to rotate tunnel log file")]
+    RotateLogError(#[error(cause)] crate::logging::RotateLogError),
+
+    /// Failure to build Wireguard configuration.
+    #[cfg(any(target_os = "linux", target_os = "macos"))]
+    #[error(display = "Failed to configure Wireguard with the given parameters")]
+    WireguardConfigError(#[error(cause)] self::wireguard::config::Error),
+
+    /// There was an error listening for events from the OpenVPN tunnel
+    #[error(display = "Failed while listening for events from the OpenVPN tunnel")]
+    OpenVpnTunnelMonitoringError(#[error(cause)] openvpn::Error),
+
+    /// There was an error listening for events from the Wireguard tunnel
+    #[cfg(any(target_os = "linux", target_os = "macos"))]
+    #[error(display = "Failed while listening for events from the Wireguard tunnel")]
+    WirguardTunnelMonitoringError(#[error(cause)] wireguard::Error),
 }
 
 
@@ -151,7 +152,7 @@ impl TunnelMonitor {
                 Self::start_wireguard_tunnel(&config, log_file, on_event)
             }
             #[cfg(any(windows, target_os = "android"))]
-            TunnelParameters::Wireguard(_) => bail!(ErrorKind::UnsupportedPlatform),
+            TunnelParameters::Wireguard(_) => Err(Error::UnsupportedPlatform),
         }
     }
 
@@ -164,8 +165,7 @@ impl TunnelMonitor {
     where
         L: Fn(TunnelEvent) + Send + Sync + Clone + 'static,
     {
-        let config = wireguard::config::Config::from_parameters(&params)
-            .chain_err(|| ErrorKind::WireguardConfigError)?;
+        let config = wireguard::config::Config::from_parameters(&params)?;
         let monitor = wireguard::WireguardMonitor::start(
             &config,
             log.as_ref().map(|p| p.as_path()),
@@ -195,7 +195,7 @@ impl TunnelMonitor {
 
     fn ensure_ipv6_can_be_used_if_enabled(tunnel_options: &GenericTunnelOptions) -> Result<()> {
         if tunnel_options.enable_ipv6 && !is_ipv6_enabled_in_os() {
-            bail!(ErrorKind::EnableIpv6Error);
+            Err(Error::EnableIpv6Error)
         } else {
             Ok(())
         }
@@ -211,7 +211,7 @@ impl TunnelMonitor {
                 TunnelParameters::Wireguard(_) => WIREGUARD_LOG_FILENAME,
             };
             let tunnel_log = log_dir.join(filename);
-            logging::rotate_log(&tunnel_log).chain_err(|| ErrorKind::RotateLogError)?;
+            logging::rotate_log(&tunnel_log)?;
             Ok(Some(tunnel_log))
         } else {
             Ok(None)
diff --git a/talpid-core/src/tunnel/openvpn.rs b/talpid-core/src/tunnel/openvpn.rs
index 8e0de74430..d8c97d468a 100644
--- a/talpid-core/src/tunnel/openvpn.rs
+++ b/talpid-core/src/tunnel/openvpn.rs
@@ -28,52 +28,70 @@ use talpid_types::net::openvpn;
 #[cfg(target_os = "linux")]
 use which;
 
-error_chain! {
-    errors {
-        /// Unable to start, wait for or kill the OpenVPN process.
-        ChildProcessError(msg: &'static str) {
-            description("Unable to start, wait for or kill the OpenVPN process")
-            display("OpenVPN process error: {}", msg)
-        }
-        /// Unable to start or manage the IPC server listening for events from OpenVPN.
-        EventDispatcherError {
-            description("Unable to start or manage the event dispatcher IPC server")
-        }
-        #[cfg(windows)]
-        /// No TAP adapter was detected
-        MissingTapAdapter {
-            description("No TAP adapter was detected")
-        }
-        #[cfg(windows)]
-        /// TAP adapter seems to be disabled
-        DisabledTapAdapter {
-            description("The TAP adapter appears to be disabled")
-        }
-        /// The IP routing program was not found.
-        #[cfg(target_os = "linux")]
-        IpRouteNotFound {
-            description("The IP routing program `ip` was not found.")
-        }
-        /// The OpenVPN binary was not found.
-        OpenVpnNotFound(path: PathBuf) {
-            description("No OpenVPN binary found")
-            display("No OpenVPN binary found at {}", path.display())
-        }
-        /// The OpenVPN plugin was not found.
-        PluginNotFound(path: PathBuf) {
-            description("No OpenVPN plugin found")
-            display("No OpenVPN plugin found at {}", path.display())
-        }
-        /// There was an error when writing authentication credentials to temporary file.
-        CredentialsWriteError {
-            description("Error while writing credentials to temporary file")
-        }
-        /// Failures related to the proxy service.
-        ProxyError(msg: String) {
-            description("Unable to start, wait for or kill the proxy service")
-            display("Proxy error: {}", msg)
-        }
-    }
+
+/// Results from fallible operations on the OpenVPN tunnel.
+pub type Result<T> = std::result::Result<T, Error>;
+
+/// Errors that can happen when using the OpenVPN tunnel.
+#[derive(err_derive::Error, Debug)]
+pub enum Error {
+    /// Unable to start, wait for or kill the OpenVPN process.
+    #[error(display = "Error in OpenVPN process management: {}", _0)]
+    ChildProcessError(&'static str, #[error(cause)] io::Error),
+
+    /// Unable to start or manage the IPC server listening for events from OpenVPN.
+    #[error(display = "Unable to start or manage the event dispatcher IPC server")]
+    EventDispatcherError(#[error(cause)] talpid_ipc::Error),
+
+    /// The OpenVPN event dispatcher exited unexpectedly
+    #[error(display = "The OpenVPN event dispatcher exited unexpectedly")]
+    EventDispatcherExited,
+
+    /// No TAP adapter was detected
+    #[cfg(windows)]
+    #[error(display = "No TAP adapter was detected")]
+    MissingTapAdapter,
+
+    /// TAP adapter seems to be disabled
+    #[cfg(windows)]
+    #[error(display = "The TAP adapter appears to be disabled")]
+    DisabledTapAdapter,
+
+    /// OpenVPN process died unexpectedly
+    #[error(display = "OpenVPN process died unexpectedly")]
+    ChildProcessDied,
+
+    /// The IP routing program was not found.
+    #[cfg(target_os = "linux")]
+    #[error(display = "The IP routing program `ip` was not found")]
+    IpRouteNotFound(#[error(cause)] failure::Compat<which::Error>),
+
+    /// The OpenVPN binary was not found.
+    #[error(display = "No OpenVPN binary found at {}", _0)]
+    OpenVpnNotFound(String),
+
+    /// The OpenVPN plugin was not found.
+    #[error(display = "No OpenVPN plugin found at {}", _0)]
+    PluginNotFound(String),
+
+    /// Error while writing credentials to temporary file.
+    #[error(display = "Error while writing credentials to temporary file")]
+    CredentialsWriteError(#[error(cause)] io::Error),
+
+    /// Failures related to the proxy service.
+    #[error(display = "Unable to start the proxy service")]
+    StartProxyError(#[error(cause)] io::Error),
+
+    /// Error while monitoring proxy service
+    #[error(display = "Error while monitoring proxy service")]
+    MonitorProxyError(#[error(cause)] io::Error),
+
+    /// The proxy exited unexpectedly
+    #[error(
+        display = "The proxy exited unexpectedly providing these details: {}",
+        _0
+    )]
+    ProxyExited(String),
 }
 
 
@@ -124,10 +142,10 @@ impl OpenVpnMonitor<OpenVpnCommand> {
     {
         let user_pass_file =
             Self::create_credentials_file(&params.config.username, &params.config.password)
-                .chain_err(|| ErrorKind::CredentialsWriteError)?;
+                .map_err(Error::CredentialsWriteError)?;
 
         let proxy_auth_file = Self::create_proxy_auth_file(&params.options.proxy)
-            .chain_err(|| ErrorKind::CredentialsWriteError)?;
+            .map_err(Error::CredentialsWriteError)?;
 
         let user_pass_file_path = user_pass_file.to_path_buf();
 
@@ -205,13 +223,13 @@ impl<C: OpenVpnBuilder + 'static> OpenVpnMonitor<C> {
         L: Fn(openvpn_plugin::EventType, HashMap<String, String>) + Send + Sync + 'static,
     {
         let event_dispatcher =
-            event_server::start(on_event).chain_err(|| ErrorKind::EventDispatcherError)?;
+            event_server::start(on_event).map_err(Error::EventDispatcherError)?;
 
         let child = cmd
             .plugin(plugin_path, vec![event_dispatcher.path().to_owned()])
             .log(log_path.as_ref().map(|p| p.as_path()))
             .start()
-            .chain_err(|| ErrorKind::ChildProcessError("Failed to start"))?;
+            .map_err(|e| Error::ChildProcessError("Failed to start", e))?;
 
         Ok(OpenVpnMonitor {
             child: Arc::new(child),
@@ -267,21 +285,13 @@ impl<C: OpenVpnBuilder + 'static> OpenVpnMonitor<C> {
                     // The proxy should never exit before openvpn.
                     match proxy_result {
                         Ok(proxy::WaitResult::ProperShutdown) => {
-                            return Err(ErrorKind::ProxyError("The proxy exited unexpectedly without providing additional details".into()).into());
+                            return Err(Error::ProxyExited("No details".to_owned()));
                         }
                         Ok(proxy::WaitResult::UnexpectedExit(details)) => {
-                            return Err(ErrorKind::ProxyError(format!(
-                                "The proxy exited unexpectedly providing these details: {}",
-                                details
-                            ))
-                            .into());
+                            return Err(Error::ProxyExited(details));
                         }
                         Err(err) => {
-                            return Err(err).chain_err(|| {
-                                ErrorKind::ProxyError(
-                                    "Failed to wait for/monitor proxy service".into(),
-                                )
-                            });
+                            return Err(err).map_err(Error::MonitorProxyError);
                         }
                     }
                 }
@@ -309,11 +319,11 @@ impl<C: OpenVpnBuilder + 'static> OpenVpnMonitor<C> {
             }
             WaitResult::Child(Err(e), _) => {
                 log::error!("OpenVPN process wait error: {}", e);
-                Err(e).chain_err(|| ErrorKind::ChildProcessError("Error when waiting"))
+                Err(Error::ChildProcessError("Error when waiting", e))
             }
             WaitResult::EventDispatcher => {
                 log::error!("OpenVPN Event server exited unexpectedly");
-                Err(ErrorKind::EventDispatcherError.into())
+                Err(Error::EventDispatcherExited)
             }
         }
     }
@@ -356,16 +366,16 @@ impl<C: OpenVpnBuilder + 'static> OpenVpnMonitor<C> {
             if let Some(log_path) = self.log_path.take() {
                 if let Ok(log) = fs::read_to_string(log_path) {
                     if log.contains("There are no TAP-Windows adapters on this system") {
-                        return ErrorKind::MissingTapAdapter.into();
+                        return Error::MissingTapAdapter;
                     }
                     if log.contains("CreateFile failed on TAP device") {
-                        return ErrorKind::DisabledTapAdapter.into();
+                        return Error::DisabledTapAdapter;
                     }
                 }
             }
         }
 
-        ErrorKind::ChildProcessError("Died unexpectedly").into()
+        Error::ChildProcessDied
     }
 
     fn create_proxy_auth_file(
@@ -388,8 +398,8 @@ impl<C: OpenVpnBuilder + 'static> OpenVpnMonitor<C> {
         proxy_resources: &ProxyResourceData,
     ) -> Result<Option<Box<dyn ProxyMonitor>>> {
         if let Some(ref settings) = proxy_settings {
-            let proxy_monitor = proxy::start_proxy(settings, proxy_resources)
-                .chain_err(|| ErrorKind::ProxyError("Failed to start proxy service".into()))?;
+            let proxy_monitor =
+                proxy::start_proxy(settings, proxy_resources).map_err(Error::StartProxyError)?;
             return Ok(Some(proxy_monitor));
         }
         Ok(None)
@@ -423,7 +433,7 @@ impl<C: OpenVpnBuilder + 'static> OpenVpnMonitor<C> {
             log::trace!("Using OpenVPN plugin at {}", path.display());
             Ok(path)
         } else {
-            bail!(ErrorKind::PluginNotFound(path));
+            Err(Error::PluginNotFound(path.display().to_string()))
         }
     }
 
@@ -443,7 +453,7 @@ impl<C: OpenVpnBuilder + 'static> OpenVpnMonitor<C> {
         cmd.iproute_bin(
             which::which("ip")
                 .compat()
-                .chain_err(|| ErrorKind::IpRouteNotFound)?,
+                .map_err(Error::IpRouteNotFound)?,
         );
         cmd.remote(params.config.get_tunnel_endpoint().endpoint)
             .user_pass(user_pass_file)
@@ -467,7 +477,7 @@ impl<C: OpenVpnBuilder + 'static> OpenVpnMonitor<C> {
             log::trace!("Using OpenVPN at {}", path.display());
             Ok(path)
         } else {
-            bail!(ErrorKind::OpenVpnNotFound(path));
+            Err(Error::OpenVpnNotFound(path.display().to_string()))
         }
     }
 
@@ -746,8 +756,8 @@ mod tests {
         let error =
             OpenVpnMonitor::new_internal(builder, |_, _| {}, "", None, TempFile::new(), None, None)
                 .unwrap_err();
-        match error.kind() {
-            ErrorKind::ChildProcessError(_) => (),
+        match error {
+            Error::ChildProcessError(..) => (),
             _ => panic!("Wrong error"),
         }
     }
diff --git a/talpid-core/src/tunnel/wireguard/mod.rs b/talpid-core/src/tunnel/wireguard/mod.rs
index d1c0c451d9..79034f22cd 100644
--- a/talpid-core/src/tunnel/wireguard/mod.rs
+++ b/talpid-core/src/tunnel/wireguard/mod.rs
@@ -1,8 +1,9 @@
 #![allow(missing_docs)]
+
 use self::config::Config;
 use super::{TunnelEvent, TunnelMetadata};
 use crate::routing;
-use std::{path::Path, sync::mpsc};
+use std::{io, path::Path, sync::mpsc};
 
 pub mod config;
 mod ping_monitor;
@@ -13,37 +14,38 @@ pub use self::wireguard_go::WgGoTunnel;
 // amount of seconds to run `ping` until it returns.
 const PING_TIMEOUT: u16 = 7;
 
-error_chain! {
-    errors {
-        /// Failed to setup a tunnel device
-        SetupTunnelDeviceError {
-            description("Failed to create tunnel device")
-        }
-        /// Failed to setup wireguard tunnel
-        StartWireguardError(status: i32) {
-            display("Failed to start wireguard tunnel - {}", status)
-        }
-        /// Failed to tear down wireguard tunnel
-        StopWireguardError(status: i32) {
-            display("Failed to stop wireguard tunnel - {}", status)
-        }
-        /// Failed to set up routing
-        SetupRoutingError {
-            display("Failed to setup routing")
-        }
-        /// Failed to move or craete a log file
-        PrepareLogFileError {
-            display("Failed to setup a logging file")
-        }
-        /// Tunnel interface name contained null bytes
-        InterfaceNameError {
-            display("Tunnel interface name contains null bytes")
-        }
-        /// Pinging timed out
-        PingTimeoutError {
-            display("Ping timed out")
-        }
-    }
+pub type Result<T> = std::result::Result<T, Error>;
+
+/// Errors that can happen in the Wireguard tunnel monitor.
+#[derive(err_derive::Error, Debug)]
+pub enum Error {
+    /// Failed to setup a tunnel device.
+    #[error(display = "Failed to create tunnel device")]
+    SetupTunnelDeviceError(#[error(cause)] crate::network_interface::Error),
+
+    /// Failed to setup wireguard tunnel.
+    #[error(display = "Failed to start wireguard tunnel - {}", status)]
+    StartWireguardError { status: i32 },
+
+    /// Failed to tear down wireguard tunnel.
+    #[error(display = "Failed to stop wireguard tunnel - {}", status)]
+    StopWireguardError { status: i32 },
+
+    /// Failed to set up routing.
+    #[error(display = "Failed to setup routing")]
+    SetupRoutingError(#[error(cause)] crate::routing::Error),
+
+    /// Failed to move or craete a log file.
+    #[error(display = "Failed to setup a logging file")]
+    PrepareLogFileError(#[error(cause)] io::Error),
+
+    /// Invalid tunnel interface name.
+    #[error(display = "Invalid tunnel interface name")]
+    InterfaceNameError(#[error(cause)] std::ffi::NulError),
+
+    /// Pinging timed out.
+    #[error(display = "Ping timed out")]
+    PingTimeoutError,
 }
 
 /// Spawns and monitors a wireguard tunnel
@@ -65,7 +67,7 @@ impl WireguardMonitor {
         on_event: F,
     ) -> Result<WireguardMonitor> {
         let tunnel = Box::new(WgGoTunnel::start_tunnel(&config, log_path)?);
-        let router = routing::RouteManager::new().chain_err(|| ErrorKind::SetupRoutingError)?;
+        let router = routing::RouteManager::new().map_err(Error::SetupRoutingError)?;
         let event_callback = Box::new(on_event.clone());
         let (close_msg_sender, close_msg_receiver) = mpsc::channel();
         let mut monitor = WireguardMonitor {
@@ -111,7 +113,7 @@ impl WireguardMonitor {
 
     pub fn wait(mut self) -> Result<()> {
         let wait_result = match self.close_msg_receiver.recv() {
-            Ok(CloseMsg::PingErr) => Err(ErrorKind::PingTimeoutError.into()),
+            Ok(CloseMsg::PingErr) => Err(Error::PingTimeoutError),
             Ok(CloseMsg::Stop) => Ok(()),
             Err(_) => Ok(()),
         };
@@ -148,7 +150,7 @@ impl WireguardMonitor {
         let default_node = self
             .router
             .get_default_route_node()
-            .chain_err(|| ErrorKind::SetupRoutingError)?;
+            .map_err(Error::SetupRoutingError)?;
 
         // route endpoints with specific routes
         for peer in config.peers.iter() {
@@ -163,7 +165,7 @@ impl WireguardMonitor {
 
         self.router
             .add_routes(required_routes)
-            .chain_err(|| ErrorKind::SetupRoutingError)
+            .map_err(Error::SetupRoutingError)
     }
 
     fn tunnel_metadata(&self, config: &Config) -> TunnelMetadata {
diff --git a/talpid-core/src/tunnel/wireguard/wireguard_go.rs b/talpid-core/src/tunnel/wireguard/wireguard_go.rs
index e713a4a190..059147286d 100644
--- a/talpid-core/src/tunnel/wireguard/wireguard_go.rs
+++ b/talpid-core/src/tunnel/wireguard/wireguard_go.rs
@@ -1,4 +1,4 @@
-use super::{Config, ErrorKind, Result, ResultExt, Tunnel};
+use super::{Config, Error, Result, Tunnel};
 use crate::network_interface::{NetworkInterface, TunnelDevice};
 use std::{ffi::CString, fs, os::unix::io::AsRawFd, path::Path};
 
@@ -14,25 +14,24 @@ pub struct WgGoTunnel {
 
 impl WgGoTunnel {
     pub fn start_tunnel(config: &Config, log_path: Option<&Path>) -> Result<Self> {
-        let mut tunnel_device =
-            TunnelDevice::new().chain_err(|| ErrorKind::SetupTunnelDeviceError)?;
+        let mut tunnel_device = TunnelDevice::new().map_err(Error::SetupTunnelDeviceError)?;
 
         for ip in config.tunnel.addresses.iter() {
             tunnel_device
                 .set_ip(*ip)
-                .chain_err(|| ErrorKind::SetupTunnelDeviceError)?;
+                .map_err(Error::SetupTunnelDeviceError)?;
         }
 
         tunnel_device
             .set_up(true)
-            .chain_err(|| ErrorKind::SetupTunnelDeviceError)?;
+            .map_err(Error::SetupTunnelDeviceError)?;
 
         let interface_name: String = tunnel_device.get_name().to_string();
         let log_file = prepare_log_file(log_path)?;
 
         let wg_config_str = config.to_userspace_format();
         let iface_name =
-            CString::new(interface_name.as_bytes()).chain_err(|| ErrorKind::InterfaceNameError)?;
+            CString::new(interface_name.as_bytes()).map_err(Error::InterfaceNameError)?;
 
         let handle = unsafe {
             wgTurnOnWithFd(
@@ -46,7 +45,7 @@ impl WgGoTunnel {
         };
 
         if handle < 0 {
-            bail!(ErrorKind::StartWireguardError(handle));
+            return Err(Error::StartWireguardError { status: handle });
         }
 
         Ok(WgGoTunnel {
@@ -61,7 +60,7 @@ impl WgGoTunnel {
         if let Some(handle) = self.handle.take() {
             let status = unsafe { wgTurnOff(handle) };
             if status < 0 {
-                bail!(ErrorKind::StopWireguardError(status))
+                return Err(Error::StopWireguardError { status });
             }
         }
         return Ok(());
@@ -77,8 +76,7 @@ impl Drop for WgGoTunnel {
 }
 
 fn prepare_log_file(log_path: Option<&Path>) -> Result<fs::File> {
-    fs::File::create(log_path.unwrap_or("/dev/null".as_ref()))
-        .chain_err(|| ErrorKind::PrepareLogFileError)
+    fs::File::create(log_path.unwrap_or("/dev/null".as_ref())).map_err(Error::PrepareLogFileError)
 }
 
 impl Tunnel for WgGoTunnel {
diff --git a/talpid-core/src/tunnel_state_machine/connecting_state.rs b/talpid-core/src/tunnel_state_machine/connecting_state.rs
index a843fa1fdd..f044c61df1 100644
--- a/talpid-core/src/tunnel_state_machine/connecting_state.rs
+++ b/talpid-core/src/tunnel_state_machine/connecting_state.rs
@@ -126,17 +126,11 @@ impl ConnectingState {
             }
             Err(error) => match error {
                 #[cfg(windows)]
-                error @ tunnel::Error(
-                    tunnel::ErrorKind::OpenVpnTunnelMonitoringError(
-                        tunnel::openvpn::ErrorKind::DisabledTapAdapter,
-                    ),
-                    _,
+                error @ tunnel::Error::OpenVpnTunnelMonitoringError(
+                    tunnel::openvpn::Error::DisabledTapAdapter,
                 )
-                | error @ tunnel::Error(
-                    tunnel::ErrorKind::OpenVpnTunnelMonitoringError(
-                        tunnel::openvpn::ErrorKind::MissingTapAdapter,
-                    ),
-                    _,
+                | error @ tunnel::Error::OpenVpnTunnelMonitoringError(
+                    tunnel::openvpn::Error::MissingTapAdapter,
                 ) => {
                     warn!(
                         "{}",
@@ -351,8 +345,8 @@ impl TunnelState for ConnectingState {
                         }
                         Err(error) => {
                             log::error!("Failed to start tunnel: {}", error);
-                            let block_reason = match *error.kind() {
-                                tunnel::ErrorKind::EnableIpv6Error => BlockReason::Ipv6Unavailable,
+                            let block_reason = match error {
+                                tunnel::Error::EnableIpv6Error => BlockReason::Ipv6Unavailable,
                                 _ => BlockReason::StartTunnelError,
                             };
                             BlockedState::enter(shared_values, block_reason)