better error for missing certificate files

made config::path pub(crate) to avoid code duplication
but not pub so it is not part of the public API

src/client/conn.rs

@@ -165,25 +165,41 @@ impl Connection {
         let mut builder = TlsConnector::builder();
 
         if let Some(cert_path) = config.cert_path() {
-            let mut file = File::open(cert_path)?;
+            if let Ok(mut file) = File::open(cert_path) {
                 let mut cert_data = vec![];
                 file.read_to_end(&mut cert_data)?;
                 let cert = Certificate::from_der(&cert_data)?;
                 builder.add_root_certificate(cert);
                 log::info!("Added {} to trusted certificates.", cert_path);
+            } else {
+                return Err(error::Error::InvalidConfig {
+                    path: config.path(),
+                    cause: error::ConfigError::FileMissing {
+                        file: cert_path.to_string(),
+                    },
+                });
+            }
         }
 
         if let Some(client_cert_path) = config.client_cert_path() {
-            let client_cert_pass = config.client_cert_pass();
+            if let Ok(mut file) = File::open(client_cert_path) {
-            let mut file = File::open(client_cert_path)?;
                 let mut client_cert_data = vec![];
                 file.read_to_end(&mut client_cert_data)?;
+                let client_cert_pass = config.client_cert_pass();
                 let pkcs12_archive = Identity::from_pkcs12(&client_cert_data, &client_cert_pass)?;
                 builder.identity(pkcs12_archive);
                 log::info!(
                     "Using {} for client certificate authentication.",
                     client_cert_path
                 );
+            } else {
+                return Err(error::Error::InvalidConfig {
+                    path: config.path(),
+                    cause: error::ConfigError::FileMissing {
+                        file: client_cert_path.to_string(),
+                    },
+                });
+            }
         }
 
         let connector: tokio_native_tls::TlsConnector = builder.build()?.into();
@@ -207,7 +223,7 @@ impl Connection {
             .add_server_trust_anchors(&TLS_SERVER_ROOTS);
 
         if let Some(cert_path) = config.cert_path() {
-            let file = File::open(cert_path)?;
+            if let Ok(mut file) = File::open(cert_path) {
                 let mut cert_data = BufReader::new(file);
                 builder
                     .root_store
@@ -216,14 +232,22 @@ impl Connection {
                         error::Error::Io(Error::new(ErrorKind::InvalidInput, "invalid cert"))
                     })?;
                 log::info!("Added {} to trusted certificates.", cert_path);
+            } else {
+                return Err(error::Error::InvalidConfig {
+                    path: config.path(),
+                    cause: error::ConfigError::FileMissing {
+                        file: cert_path.to_string(),
+                    },
+                });
+            }
         }
 
         if let Some(client_cert_path) = config.client_cert_path() {
-            let client_cert_pass = PrivateKey(Vec::from(config.client_cert_pass()));
+            if let Ok(mut file) = File::open(client_cert_path) {
-            let file = File::open(client_cert_path)?;
                 let client_cert_data = certs(&mut BufReader::new(file)).map_err(|_| {
                     error::Error::Io(Error::new(ErrorKind::InvalidInput, "invalid cert"))
                 })?;
+                let client_cert_pass = PrivateKey(Vec::from(config.client_cert_pass()));
                 builder
                     .set_single_client_cert(client_cert_data, client_cert_pass)
                     .map_err(|err| error::Error::Io(Error::new(ErrorKind::InvalidInput, err)))?;
@@ -231,6 +255,14 @@ impl Connection {
                     "Using {} for client certificate authentication.",
                     client_cert_path
                 );
+            } else {
+                return Err(error::Error::InvalidConfig {
+                    path: config.path(),
+                    cause: error::ConfigError::FileMissing {
+                        file: client_cert_path.to_string(),
+                    },
+                });
+            }
         }
 
         let connector = TlsConnector::from(Arc::new(builder));

src/client/data/config.rs

@@ -224,7 +224,8 @@ impl Config {
         self
     }
 
-    fn path(&self) -> String {
+    /// Returns the location this Config was loaded from or `<none>`.
+    pub(crate) fn path(&self) -> String {
         self.path
             .as_ref()
             .map(|buf| buf.to_string_lossy().into_owned())