Provide semantically meaningful exceptions for translation

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

18 files changed, 364 insertions, 186 deletions

diff --git a/app/src/main/java/com/wireguard/android/configStore/FileConfigStore.java b/app/src/main/java/com/wireguard/android/configStore/FileConfigStore.java
index a637eba4..d562c192 100644
--- a/app/src/main/java/com/wireguard/android/configStore/FileConfigStore.java
+++ b/app/src/main/java/com/wireguard/android/configStore/FileConfigStore.java
@@ -9,8 +9,8 @@ import android.content.Context;
 import android.util.Log;
 
 import com.wireguard.android.R;
+import com.wireguard.config.BadConfigException;
 import com.wireguard.config.Config;
-import com.wireguard.config.ParseException;
 
 import java.io.File;
 import java.io.FileInputStream;
@@ -69,7 +69,7 @@ public final class FileConfigStore implements ConfigStore {
     }
 
     @Override
-    public Config load(final String name) throws IOException, ParseException {
+    public Config load(final String name) throws BadConfigException, IOException {
         try (final FileInputStream stream = new FileInputStream(fileFor(name))) {
             return Config.parse(stream);
         }
diff --git a/app/src/main/java/com/wireguard/android/fragment/ConfigNamingDialogFragment.java b/app/src/main/java/com/wireguard/android/fragment/ConfigNamingDialogFragment.java
index 9c8a300d..2cdf79ae 100644
--- a/app/src/main/java/com/wireguard/android/fragment/ConfigNamingDialogFragment.java
+++ b/app/src/main/java/com/wireguard/android/fragment/ConfigNamingDialogFragment.java
@@ -18,8 +18,8 @@ import android.view.inputmethod.InputMethodManager;
 import com.wireguard.android.Application;
 import com.wireguard.android.R;
 import com.wireguard.android.databinding.ConfigNamingDialogFragmentBinding;
+import com.wireguard.config.BadConfigException;
 import com.wireguard.config.Config;
-import com.wireguard.config.ParseException;
 
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
@@ -67,8 +67,8 @@ public class ConfigNamingDialogFragment extends DialogFragment {
 
         try {
             config = Config.parse(new ByteArrayInputStream(getArguments().getString(KEY_CONFIG_TEXT).getBytes(StandardCharsets.UTF_8)));
-        } catch (final IOException | ParseException exception) {
-            throw new RuntimeException(getResources().getString(R.string.invalid_config_error, getClass().getSimpleName()), exception);
+        } catch (final BadConfigException | IOException e) {
+            throw new RuntimeException(getResources().getString(R.string.invalid_config_error, getClass().getSimpleName()), e);
         }
     }
 
diff --git a/app/src/main/java/com/wireguard/android/fragment/TunnelListFragment.java b/app/src/main/java/com/wireguard/android/fragment/TunnelListFragment.java
index bbcbab94..4a6103ba 100644
--- a/app/src/main/java/com/wireguard/android/fragment/TunnelListFragment.java
+++ b/app/src/main/java/com/wireguard/android/fragment/TunnelListFragment.java
@@ -40,8 +40,8 @@ import com.wireguard.android.model.Tunnel;
 import com.wireguard.android.util.ExceptionLoggers;
 import com.wireguard.android.widget.MultiselectableRelativeLayout;
 import com.wireguard.android.widget.fab.FloatingActionsMenuRecyclerViewScrollListener;
+import com.wireguard.config.BadConfigException;
 import com.wireguard.config.Config;
-import com.wireguard.config.ParseException;
 
 import java.io.BufferedReader;
 import java.io.ByteArrayInputStream;
@@ -89,8 +89,8 @@ public class TunnelListFragment extends BaseFragment {
             final FragmentManager fragmentManager = getFragmentManager();
             if (fragmentManager != null)
                 ConfigNamingDialogFragment.newInstance(configText).show(fragmentManager, null);
-        } catch (final IllegalArgumentException | IOException | ParseException exception) {
-            onTunnelImportFinished(Collections.emptyList(), Collections.singletonList(exception));
+        } catch (final BadConfigException | IOException e) {
+            onTunnelImportFinished(Collections.emptyList(), Collections.singletonList(e));
         }
     }
 
diff --git a/app/src/main/java/com/wireguard/android/util/ExceptionLoggers.java b/app/src/main/java/com/wireguard/android/util/ExceptionLoggers.java
index f9cadf5f..3cb5ca9f 100644
--- a/app/src/main/java/com/wireguard/android/util/ExceptionLoggers.java
+++ b/app/src/main/java/com/wireguard/android/util/ExceptionLoggers.java
@@ -11,8 +11,9 @@ import android.util.Log;
 
 import com.wireguard.android.Application;
 import com.wireguard.android.R;
+import com.wireguard.config.BadConfigException;
 import com.wireguard.config.ParseException;
-import com.wireguard.crypto.Key;
+import com.wireguard.crypto.KeyFormatException;
 
 import java9.util.concurrent.CompletionException;
 import java9.util.function.BiConsumer;
@@ -37,6 +38,8 @@ public enum ExceptionLoggers implements BiConsumer<Object, Throwable> {
     public static Throwable unwrap(final Throwable throwable) {
         if (throwable instanceof CompletionException && throwable.getCause() != null)
             return throwable.getCause();
+        if (throwable instanceof ParseException && throwable.getCause() != null)
+            return throwable.getCause();
         return throwable;
     }
 
@@ -44,13 +47,14 @@ public enum ExceptionLoggers implements BiConsumer<Object, Throwable> {
         final Throwable innerThrowable = unwrap(throwable);
         final Resources resources = Application.get().getResources();
         String message;
-        if (innerThrowable instanceof ParseException) {
-            final ParseException parseException = (ParseException) innerThrowable;
-            message = resources.getString(R.string.parse_error, parseException.getText(), parseException.getContext());
-            if (parseException.getMessage() != null)
-                message += ": " + parseException.getMessage();
-        } else if (innerThrowable instanceof Key.KeyFormatException) {
-            final Key.KeyFormatException keyFormatException = (Key.KeyFormatException) innerThrowable;
+        if (innerThrowable instanceof BadConfigException) {
+            final BadConfigException configException = (BadConfigException) innerThrowable;
+            message = resources.getString(R.string.parse_error, configException.getText(), configException.getLocation());
+            final Throwable cause = unwrap(configException);
+            if (cause.getMessage() != null)
+                message += ": " + cause.getMessage();
+        } else if (innerThrowable instanceof KeyFormatException) {
+            final KeyFormatException keyFormatException = (KeyFormatException) innerThrowable;
             switch (keyFormatException.getFormat()) {
                 case BASE64:
                     message = resources.getString(R.string.key_length_base64_exception_message);
diff --git a/app/src/main/java/com/wireguard/android/viewmodel/ConfigProxy.java b/app/src/main/java/com/wireguard/android/viewmodel/ConfigProxy.java
index abe8cbcf..62523298 100644
--- a/app/src/main/java/com/wireguard/android/viewmodel/ConfigProxy.java
+++ b/app/src/main/java/com/wireguard/android/viewmodel/ConfigProxy.java
@@ -10,8 +10,8 @@ import android.databinding.ObservableList;
 import android.os.Parcel;
 import android.os.Parcelable;
 
+import com.wireguard.config.BadConfigException;
 import com.wireguard.config.Config;
-import com.wireguard.config.ParseException;
 import com.wireguard.config.Peer;
 
 import java.util.ArrayList;
@@ -63,7 +63,7 @@ public class ConfigProxy implements Parcelable {
         return peers;
     }
 
-    public Config resolve() throws ParseException {
+    public Config resolve() throws BadConfigException {
         final Collection<Peer> resolvedPeers = new ArrayList<>();
         for (final PeerProxy proxy : peers)
             resolvedPeers.add(proxy.resolve());
diff --git a/app/src/main/java/com/wireguard/android/viewmodel/InterfaceProxy.java b/app/src/main/java/com/wireguard/android/viewmodel/InterfaceProxy.java
index 63d82042..3b303f42 100644
--- a/app/src/main/java/com/wireguard/android/viewmodel/InterfaceProxy.java
+++ b/app/src/main/java/com/wireguard/android/viewmodel/InterfaceProxy.java
@@ -14,9 +14,10 @@ import android.os.Parcelable;
 
 import com.wireguard.android.BR;
 import com.wireguard.config.Attribute;
+import com.wireguard.config.BadConfigException;
 import com.wireguard.config.Interface;
-import com.wireguard.config.ParseException;
 import com.wireguard.crypto.Key;
+import com.wireguard.crypto.KeyFormatException;
 import com.wireguard.crypto.KeyPair;
 
 import java.net.InetAddress;
@@ -116,7 +117,7 @@ public class InterfaceProxy extends BaseObservable implements Parcelable {
         return publicKey;
     }
 
-    public Interface resolve() throws ParseException {
+    public Interface resolve() throws BadConfigException {
         final Interface.Builder builder = new Interface.Builder();
         if (!addresses.isEmpty())
             builder.parseAddresses(addresses);
@@ -157,7 +158,7 @@ public class InterfaceProxy extends BaseObservable implements Parcelable {
         this.privateKey = privateKey;
         try {
             publicKey = new KeyPair(Key.fromBase64(privateKey)).getPublicKey().toBase64();
-        } catch (final Key.KeyFormatException ignored) {
+        } catch (final KeyFormatException ignored) {
             publicKey = "";
         }
         notifyPropertyChanged(BR.privateKey);
diff --git a/app/src/main/java/com/wireguard/android/viewmodel/PeerProxy.java b/app/src/main/java/com/wireguard/android/viewmodel/PeerProxy.java
index 822a4278..c9bae98f 100644
--- a/app/src/main/java/com/wireguard/android/viewmodel/PeerProxy.java
+++ b/app/src/main/java/com/wireguard/android/viewmodel/PeerProxy.java
@@ -15,8 +15,8 @@ import android.support.annotation.Nullable;
 
 import com.wireguard.android.BR;
 import com.wireguard.config.Attribute;
+import com.wireguard.config.BadConfigException;
 import com.wireguard.config.InetEndpoint;
-import com.wireguard.config.ParseException;
 import com.wireguard.config.Peer;
 import com.wireguard.crypto.Key;
 
@@ -164,7 +164,7 @@ public class PeerProxy extends BaseObservable implements Parcelable {
         return allowedIpsState == AllowedIpsState.CONTAINS_IPV4_PUBLIC_NETWORKS;
     }
 
-    public Peer resolve() throws ParseException {
+    public Peer resolve() throws BadConfigException {
         final Peer.Builder builder = new Peer.Builder();
         if (!allowedIps.isEmpty())
             builder.parseAllowedIPs(allowedIps);
diff --git a/app/src/main/java/com/wireguard/config/BadConfigException.java b/app/src/main/java/com/wireguard/config/BadConfigException.java
new file mode 100644
index 00000000..7f794a35
--- /dev/null
+++ b/app/src/main/java/com/wireguard/config/BadConfigException.java
@@ -0,0 +1,118 @@
+/*
+ * Copyright © 2018 WireGuard LLC. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.wireguard.config;
+
+import android.support.annotation.Nullable;
+
+import com.wireguard.crypto.KeyFormatException;
+
+public class BadConfigException extends Exception {
+    private final Location location;
+    private final Reason reason;
+    private final Section section;
+    @Nullable private final CharSequence text;
+
+    private BadConfigException(final Section section, final Location location,
+                               final Reason reason, @Nullable final CharSequence text,
+                               @Nullable final Throwable cause) {
+        super(cause);
+        this.section = section;
+        this.location = location;
+        this.reason = reason;
+        this.text = text;
+    }
+
+    public BadConfigException(final Section section, final Location location,
+                              final Reason reason, @Nullable final CharSequence text) {
+        this(section, location, reason, text, null);
+    }
+
+    public BadConfigException(final Section section, final Location location,
+                              final KeyFormatException cause) {
+        this(section, location, Reason.INVALID_KEY, null, cause);
+    }
+
+    public BadConfigException(final Section section, final Location location,
+                              @Nullable final CharSequence text,
+                              final NumberFormatException cause) {
+        this(section, location, Reason.INVALID_NUMBER, text, cause);
+    }
+
+    public BadConfigException(final Section section, final Location location,
+                              final ParseException cause) {
+        this(section, location, Reason.INVALID_VALUE, cause.getText(), cause);
+    }
+
+    public Location getLocation() {
+        return location;
+    }
+
+    public Reason getReason() {
+        return reason;
+    }
+
+    public Section getSection() {
+        return section;
+    }
+
+    @Nullable
+    public CharSequence getText() {
+        return text;
+    }
+
+    public enum Location {
+        TOP_LEVEL(""),
+        ADDRESS("Address"),
+        ALLOWED_IPS("AllowedIPs"),
+        DNS("DNS"),
+        ENDPOINT("Endpoint"),
+        EXCLUDED_APPLICATIONS("ExcludedApplications"),
+        LISTEN_PORT("ListenPort"),
+        MTU("MTU"),
+        PERSISTENT_KEEPALIVE("PersistentKeepalive"),
+        PRE_SHARED_KEY("PresharedKey"),
+        PRIVATE_KEY("PrivateKey"),
+        PUBLIC_KEY("PublicKey");
+
+        private final String name;
+
+        Location(final String name) {
+            this.name = name;
+        }
+
+        public String getName() {
+            return name;
+        }
+    }
+
+    public enum Reason {
+        INVALID_KEY,
+        INVALID_NUMBER,
+        INVALID_VALUE,
+        MISSING_ATTRIBUTE,
+        MISSING_SECTION,
+        MISSING_VALUE,
+        SYNTAX_ERROR,
+        UNKNOWN_ATTRIBUTE,
+        UNKNOWN_SECTION
+    }
+
+    public enum Section {
+        CONFIG("Config"),
+        INTERFACE("Interface"),
+        PEER("Peer");
+
+        private final String name;
+
+        Section(final String name) {
+            this.name = name;
+        }
+
+        public String getName() {
+            return name;
+        }
+    }
+}
diff --git a/app/src/main/java/com/wireguard/config/Config.java b/app/src/main/java/com/wireguard/config/Config.java
index d2c1395f..8b393bef 100644
--- a/app/src/main/java/com/wireguard/config/Config.java
+++ b/app/src/main/java/com/wireguard/config/Config.java
@@ -7,6 +7,10 @@ package com.wireguard.config;
 
 import android.support.annotation.Nullable;
 
+import com.wireguard.config.BadConfigException.Location;
+import com.wireguard.config.BadConfigException.Reason;
+import com.wireguard.config.BadConfigException.Section;
+
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStream;
@@ -37,23 +41,27 @@ public final class Config {
 
     /**
      * Parses an series of "Interface" and "Peer" sections into a {@code Config}. Throws
-     * {@link ParseException} if the input is not well-formed or contains unparseable sections.
+     * {@link BadConfigException} if the input is not well-formed or contains data that cannot
+     * be parsed.
      *
-     * @param stream a stream of UTF-8 text that is interpreted as a WireGuard configuration file
+     * @param stream a stream of UTF-8 text that is interpreted as a WireGuard configuration
      * @return a {@code Config} instance representing the supplied configuration
      */
-    public static Config parse(final InputStream stream) throws IOException, ParseException {
+    public static Config parse(final InputStream stream)
+            throws IOException, BadConfigException {
         return parse(new BufferedReader(new InputStreamReader(stream)));
     }
 
     /**
      * Parses an series of "Interface" and "Peer" sections into a {@code Config}. Throws
-     * {@link ParseException} if the input is not well-formed or contains unparseable sections.
+     * {@link BadConfigException} if the input is not well-formed or contains data that cannot
+     * be parsed.
      *
-     * @param reader a BufferedReader of UTF-8 text that is interpreted as a WireGuard configuration file
+     * @param reader a BufferedReader of UTF-8 text that is interpreted as a WireGuard configuration
      * @return a {@code Config} instance representing the supplied configuration
      */
-    public static Config parse(final BufferedReader reader) throws IOException, ParseException {
+    public static Config parse(final BufferedReader reader)
+            throws IOException, BadConfigException {
         final Builder builder = new Builder();
         final Collection<String> interfaceLines = new ArrayList<>();
         final Collection<String> peerLines = new ArrayList<>();
@@ -80,20 +88,23 @@ public final class Config {
                     inInterfaceSection = false;
                     inPeerSection = true;
                 } else {
-                    throw new ParseException("top level", line, "Unknown section name");
+                    throw new BadConfigException(Section.CONFIG, Location.TOP_LEVEL,
+                            Reason.UNKNOWN_SECTION, line);
                 }
             } else if (inInterfaceSection) {
                 interfaceLines.add(line);
             } else if (inPeerSection) {
                 peerLines.add(line);
             } else {
-                throw new ParseException("top level", line, "Expected [Interface] or [Peer]");
+                throw new BadConfigException(Section.CONFIG, Location.TOP_LEVEL,
+                        Reason.UNKNOWN_SECTION, line);
             }
         }
         if (inPeerSection)
             builder.parsePeer(peerLines);
         else if (!inInterfaceSection)
-            throw new ParseException("top level", "", "Empty configuration");
+            throw new BadConfigException(Section.CONFIG, Location.TOP_LEVEL,
+                    Reason.MISSING_SECTION, null);
         // Combine all [Interface] sections in the file.
         builder.parseInterface(interfaceLines);
         return builder.build();
@@ -192,11 +203,13 @@ public final class Config {
             return new Config(this);
         }
 
-        public Builder parseInterface(final Iterable<? extends CharSequence> lines) throws ParseException {
+        public Builder parseInterface(final Iterable<? extends CharSequence> lines)
+                throws BadConfigException {
             return setInterface(Interface.parse(lines));
         }
 
-        public Builder parsePeer(final Iterable<? extends CharSequence> lines) throws ParseException {
+        public Builder parsePeer(final Iterable<? extends CharSequence> lines)
+                throws BadConfigException {
             return addPeer(Peer.parse(lines));
         }
 
diff --git a/app/src/main/java/com/wireguard/config/InetAddresses.java b/app/src/main/java/com/wireguard/config/InetAddresses.java
index 989598da..487b136c 100644
--- a/app/src/main/java/com/wireguard/config/InetAddresses.java
+++ b/app/src/main/java/com/wireguard/config/InetAddresses.java
@@ -37,17 +37,18 @@ public final class InetAddresses {
      * @param address a string representing the IP address
      * @return an instance of {@link Inet4Address} or {@link Inet6Address}, as appropriate
      */
-    public static InetAddress parse(final String address) {
+    public static InetAddress parse(final String address) throws ParseException {
         if (address.isEmpty())
-            throw new IllegalArgumentException("Empty address");
+            throw new ParseException(InetAddress.class, address, "Empty address");
         try {
             return (InetAddress) PARSER_METHOD.invoke(null, address);
         } catch (final IllegalAccessException | InvocationTargetException e) {
             final Throwable cause = e.getCause();
             // Re-throw parsing exceptions with the original type, as callers might try to catch
             // them. On the other hand, callers cannot be expected to handle reflection failures.
-            throw cause instanceof IllegalArgumentException ?
-                    (IllegalArgumentException) cause : new RuntimeException(e);
+            if (cause instanceof IllegalArgumentException)
+                throw new ParseException(InetAddress.class, address, cause);
+            throw new RuntimeException(e);
         }
     }
 }
diff --git a/app/src/main/java/com/wireguard/config/InetEndpoint.java b/app/src/main/java/com/wireguard/config/InetEndpoint.java
index 355b325a..f64bc25a 100644
--- a/app/src/main/java/com/wireguard/config/InetEndpoint.java
+++ b/app/src/main/java/com/wireguard/config/InetEndpoint.java
@@ -42,9 +42,9 @@ public final class InetEndpoint {
         this.port = port;
     }
 
-    public static InetEndpoint parse(final String endpoint) {
+    public static InetEndpoint parse(final String endpoint) throws ParseException {
         if (FORBIDDEN_CHARACTERS.matcher(endpoint).find())
-            throw new IllegalArgumentException("Forbidden characters in endpoint");
+            throw new ParseException(InetEndpoint.class, endpoint, "Forbidden characters");
         final URI uri;
         try {
             uri = new URI("wg://" + endpoint);
@@ -52,12 +52,12 @@ public final class InetEndpoint {
             throw new IllegalArgumentException(e);
         }
         if (uri.getPort() < 0)
-            throw new IllegalArgumentException("An endpoint must specify a port (e.g. 51820)");
+            throw new ParseException(InetEndpoint.class, endpoint, "Missing/invalid port number");
         try {
             InetAddresses.parse(uri.getHost());
             // Parsing ths host as a numeric address worked, so we don't need to do DNS lookups.
             return new InetEndpoint(uri.getHost(), true, uri.getPort());
-        } catch (final IllegalArgumentException ignored) {
+        } catch (final ParseException ignored) {
             // Failed to parse the host as a numeric address, so it must be a DNS hostname/FQDN.
             return new InetEndpoint(uri.getHost(), false, uri.getPort());
         }
diff --git a/app/src/main/java/com/wireguard/config/InetNetwork.java b/app/src/main/java/com/wireguard/config/InetNetwork.java
index 9e5e8c64..444af58e 100644
--- a/app/src/main/java/com/wireguard/config/InetNetwork.java
+++ b/app/src/main/java/com/wireguard/config/InetNetwork.java
@@ -22,19 +22,28 @@ public final class InetNetwork {
         this.mask = mask;
     }
 
-    public static InetNetwork parse(final String network) {
+    public static InetNetwork parse(final String network) throws ParseException {
         final int slash = network.lastIndexOf('/');
+        final String maskString;
         final int rawMask;
         final String rawAddress;
         if (slash >= 0) {
-            rawMask = Integer.parseInt(network.substring(slash + 1), 10);
+            maskString = network.substring(slash + 1);
+            try {
+                rawMask = Integer.parseInt(maskString, 10);
+            } catch (final NumberFormatException ignored) {
+                throw new ParseException(Integer.class, maskString);
+            }
             rawAddress = network.substring(0, slash);
         } else {
+            maskString = "";
             rawMask = -1;
             rawAddress = network;
         }
         final InetAddress address = InetAddresses.parse(rawAddress);
         final int maxMask = (address instanceof Inet4Address) ? 32 : 128;
+        if (rawMask > maxMask)
+            throw new ParseException(InetNetwork.class, maskString, "Invalid network mask");
         final int mask = rawMask >= 0 && rawMask <= maxMask ? rawMask : maxMask;
         return new InetNetwork(address, mask);
     }
diff --git a/app/src/main/java/com/wireguard/config/Interface.java b/app/src/main/java/com/wireguard/config/Interface.java
index da30fbcc..2fd34a32 100644
--- a/app/src/main/java/com/wireguard/config/Interface.java
+++ b/app/src/main/java/com/wireguard/config/Interface.java
@@ -7,7 +7,11 @@ package com.wireguard.config;
 
 import android.support.annotation.Nullable;
 
+import com.wireguard.config.BadConfigException.Location;
+import com.wireguard.config.BadConfigException.Reason;
+import com.wireguard.config.BadConfigException.Section;
 import com.wireguard.crypto.Key;
+import com.wireguard.crypto.KeyFormatException;
 import com.wireguard.crypto.KeyPair;
 
 import java.net.InetAddress;
@@ -22,7 +26,6 @@ import java.util.Set;
 import java9.util.Lists;
 import java9.util.Optional;
 import java9.util.stream.Collectors;
-import java9.util.stream.Stream;
 import java9.util.stream.StreamSupport;
 
 /**
@@ -60,11 +63,13 @@ public final class Interface {
      * @param lines An iterable sequence of lines, containing at least a private key attribute
      * @return An {@code Interface} with all of the attributes from {@code lines} set
      */
-    public static Interface parse(final Iterable<? extends CharSequence> lines) throws ParseException {
+    public static Interface parse(final Iterable<? extends CharSequence> lines)
+            throws BadConfigException {
         final Builder builder = new Builder();
         for (final CharSequence line : lines) {
-            final Attribute attribute = Attribute.parse(line)
-                    .orElseThrow(() -> new ParseException("[Interface]", line, "Syntax error"));
+            final Attribute attribute = Attribute.parse(line).orElseThrow(() ->
+                    new BadConfigException(Section.INTERFACE, Location.TOP_LEVEL,
+                            Reason.SYNTAX_ERROR, line));
             switch (attribute.getKey().toLowerCase(Locale.ENGLISH)) {
                 case "address":
                     builder.parseAddresses(attribute.getValue());
@@ -85,7 +90,8 @@ public final class Interface {
                     builder.parsePrivateKey(attribute.getValue());
                     break;
                 default:
-                    throw new ParseException("[Interface]", attribute.getKey(), "Unknown attribute");
+                    throw new BadConfigException(Section.INTERFACE, Location.TOP_LEVEL,
+                            Reason.UNKNOWN_ATTRIBUTE, attribute.getKey());
             }
         }
         return builder.build();
@@ -260,9 +266,10 @@ public final class Interface {
             return this;
         }
 
-        public Interface build() {
+        public Interface build() throws BadConfigException {
             if (keyPair == null)
-                throw new IllegalArgumentException("Interfaces must have a private key");
+                throw new BadConfigException(Section.INTERFACE, Location.PRIVATE_KEY,
+                        Reason.MISSING_ATTRIBUTE, null);
             return new Interface(this);
         }
 
@@ -276,57 +283,51 @@ public final class Interface {
             return this;
         }
 
-        public Builder parseAddresses(final CharSequence addresses) throws ParseException {
+        public Builder parseAddresses(final CharSequence addresses) throws BadConfigException {
             try {
-                final List<InetNetwork> parsed = Stream.of(Attribute.split(addresses))
-                        .map(InetNetwork::parse)
-                        .collect(Collectors.toUnmodifiableList());
-                return addAddresses(parsed);
-            } catch (final IllegalArgumentException e) {
-                throw new ParseException("Address", addresses, e);
+                for (final String address : Attribute.split(addresses))
+                    addAddress(InetNetwork.parse(address));
+                return this;
+            } catch (final ParseException e) {
+                throw new BadConfigException(Section.INTERFACE, Location.ADDRESS, e);
             }
         }
 
-        public Builder parseDnsServers(final CharSequence dnsServers) throws ParseException {
+        public Builder parseDnsServers(final CharSequence dnsServers) throws BadConfigException {
             try {
-                final List<InetAddress> parsed = Stream.of(Attribute.split(dnsServers))
-                        .map(InetAddresses::parse)
-                        .collect(Collectors.toUnmodifiableList());
-                return addDnsServers(parsed);
-            } catch (final IllegalArgumentException e) {
-                throw new ParseException("DNS", dnsServers, e);
+                for (final String dnsServer : Attribute.split(dnsServers))
+                    addDnsServer(InetAddresses.parse(dnsServer));
+                return this;
+            } catch (final ParseException e) {
+                throw new BadConfigException(Section.INTERFACE, Location.DNS, e);
             }
         }
 
-        public Builder parseExcludedApplications(final CharSequence apps) throws ParseException {
-            try {
-                return excludeApplications(Lists.of(Attribute.split(apps)));
-            } catch (final IllegalArgumentException e) {
-                throw new ParseException("ExcludedApplications", apps, e);
-            }
+        public Builder parseExcludedApplications(final CharSequence apps) {
+            return excludeApplications(Lists.of(Attribute.split(apps)));
         }
 
-        public Builder parseListenPort(final String listenPort) throws ParseException {
+        public Builder parseListenPort(final String listenPort) throws BadConfigException {
             try {
                 return setListenPort(Integer.parseInt(listenPort));
-            } catch (final IllegalArgumentException e) {
-                throw new ParseException("ListenPort", listenPort, e);
+            } catch (final NumberFormatException e) {
+                throw new BadConfigException(Section.INTERFACE, Location.LISTEN_PORT, listenPort, e);
             }
         }
 
-        public Builder parseMtu(final String mtu) throws ParseException {
+        public Builder parseMtu(final String mtu) throws BadConfigException {
             try {
                 return setMtu(Integer.parseInt(mtu));
-            } catch (final IllegalArgumentException e) {
-                throw new ParseException("MTU", mtu, e);
+            } catch (final NumberFormatException e) {
+                throw new BadConfigException(Section.INTERFACE, Location.MTU, mtu, e);
             }
         }
 
-        public Builder parsePrivateKey(final String privateKey) throws ParseException {
+        public Builder parsePrivateKey(final String privateKey) throws BadConfigException {
             try {
                 return setKeyPair(new KeyPair(Key.fromBase64(privateKey)));
-            } catch (final Key.KeyFormatException e) {
-                throw new ParseException("PrivateKey", "(omitted)", e);
+            } catch (final KeyFormatException e) {
+                throw new BadConfigException(Section.INTERFACE, Location.PRIVATE_KEY, e);
             }
         }
 
@@ -335,16 +336,18 @@ public final class Interface {
             return this;
         }
 
-        public Builder setListenPort(final int listenPort) {
+        public Builder setListenPort(final int listenPort) throws BadConfigException {
             if (listenPort < MIN_UDP_PORT || listenPort > MAX_UDP_PORT)
-                throw new IllegalArgumentException("ListenPort must be a valid UDP port number");
+                throw new BadConfigException(Section.INTERFACE, Location.LISTEN_PORT,
+                        Reason.INVALID_VALUE, String.valueOf(listenPort));
             this.listenPort = listenPort == 0 ? Optional.empty() : Optional.of(listenPort);
             return this;
         }
 
-        public Builder setMtu(final int mtu) {
+        public Builder setMtu(final int mtu) throws BadConfigException {
             if (mtu < 0)
-                throw new IllegalArgumentException("MTU must not be negative");
+                throw new BadConfigException(Section.INTERFACE, Location.LISTEN_PORT,
+                        Reason.INVALID_VALUE, String.valueOf(mtu));
             this.mtu = mtu == 0 ? Optional.empty() : Optional.of(mtu);
             return this;
         }
diff --git a/app/src/main/java/com/wireguard/config/ParseException.java b/app/src/main/java/com/wireguard/config/ParseException.java
index 1fccb534..c8482af2 100644
--- a/app/src/main/java/com/wireguard/config/ParseException.java
+++ b/app/src/main/java/com/wireguard/config/ParseException.java
@@ -5,34 +5,37 @@
 
 package com.wireguard.config;
 
+import android.support.annotation.Nullable;
+
 /**
- * An exception representing a failure to parse an element of a WireGuard configuration. The context
- * for this failure can be retrieved with {@link #getContext}, and the text that failed to parse can
- * be retrieved with {@link #getText}.
  */
 public class ParseException extends Exception {
-    private final String context;
+    private final Class<?> parsingClass;
     private final CharSequence text;
 
-    public ParseException(final String context, final CharSequence text, final String message) {
-        super(message);
-        this.context = context;
+    public ParseException(final Class<?> parsingClass, final CharSequence text,
+                          @Nullable final String message, @Nullable final Throwable cause) {
+        super(message, cause);
+        this.parsingClass = parsingClass;
         this.text = text;
     }
 
-    public ParseException(final String context, final CharSequence text, final Throwable cause) {
-        super(cause.getMessage(), cause);
-        this.context = context;
-        this.text = text;
+    public ParseException(final Class<?> parsingClass, final CharSequence text,
+                          @Nullable final String message) {
+        this(parsingClass, text, message, null);
     }
 
-    public ParseException(final String context, final CharSequence text) {
-        this.context = context;
-        this.text = text;
+    public ParseException(final Class<?> parsingClass, final CharSequence text,
+                          @Nullable final Throwable cause) {
+        this(parsingClass, text, null, cause);
+    }
+
+    public ParseException(final Class<?> parsingClass, final CharSequence text) {
+        this(parsingClass, text, null, null);
     }
 
-    public String getContext() {
-        return context;
+    public Class<?> getParsingClass() {
+        return parsingClass;
     }
 
     public CharSequence getText() {
diff --git a/app/src/main/java/com/wireguard/config/Peer.java b/app/src/main/java/com/wireguard/config/Peer.java
index 1250fcb3..cdea030a 100644
--- a/app/src/main/java/com/wireguard/config/Peer.java
+++ b/app/src/main/java/com/wireguard/config/Peer.java
@@ -7,19 +7,20 @@ package com.wireguard.config;
 
 import android.support.annotation.Nullable;
 
+import com.wireguard.config.BadConfigException.Location;
+import com.wireguard.config.BadConfigException.Reason;
+import com.wireguard.config.BadConfigException.Section;
 import com.wireguard.crypto.Key;
+import com.wireguard.crypto.KeyFormatException;
 
 import java.util.Collection;
 import java.util.Collections;
 import java.util.LinkedHashSet;
-import java.util.List;
 import java.util.Locale;
 import java.util.Objects;
 import java.util.Set;
 
 import java9.util.Optional;
-import java9.util.stream.Collectors;
-import java9.util.stream.Stream;
 
 /**
  * Represents the configuration for a WireGuard peer (a [Peer] block). Peers must have a public key,
@@ -50,11 +51,13 @@ public final class Peer {
      * @param lines an iterable sequence of lines, containing at least a public key attribute
      * @return a {@code Peer} with all of its attributes set from {@code lines}
      */
-    public static Peer parse(final Iterable<? extends CharSequence> lines) throws ParseException {
+    public static Peer parse(final Iterable<? extends CharSequence> lines)
+            throws BadConfigException {
         final Builder builder = new Builder();
         for (final CharSequence line : lines) {
-            final Attribute attribute = Attribute.parse(line)
-                    .orElseThrow(() -> new ParseException("[Peer]", line, "Syntax error"));
+            final Attribute attribute = Attribute.parse(line).orElseThrow(() ->
+                    new BadConfigException(Section.PEER, Location.TOP_LEVEL,
+                            Reason.SYNTAX_ERROR, line));
             switch (attribute.getKey().toLowerCase(Locale.ENGLISH)) {
                 case "allowedips":
                     builder.parseAllowedIPs(attribute.getValue());
@@ -72,7 +75,8 @@ public final class Peer {
                     builder.parsePublicKey(attribute.getValue());
                     break;
                 default:
-                    throw new ParseException("[Peer]", line, "Unknown attribute");
+                    throw new BadConfigException(Section.PEER, Location.TOP_LEVEL,
+                            Reason.UNKNOWN_ATTRIBUTE, attribute.getKey());
             }
         }
         return builder.build();
@@ -223,52 +227,54 @@ public final class Peer {
             return this;
         }
 
-        public Peer build() {
+        public Peer build() throws BadConfigException {
             if (publicKey == null)
-                throw new IllegalArgumentException("Peers must have a public key");
+                throw new BadConfigException(Section.PEER, Location.PUBLIC_KEY,
+                        Reason.MISSING_ATTRIBUTE, null);
             return new Peer(this);
         }
 
-        public Builder parseAllowedIPs(final CharSequence allowedIps) throws ParseException {
+        public Builder parseAllowedIPs(final CharSequence allowedIps) throws BadConfigException {
             try {
-                final List<InetNetwork> parsed = Stream.of(Attribute.split(allowedIps))
-                        .map(InetNetwork::parse)
-                        .collect(Collectors.toUnmodifiableList());
-                return addAllowedIps(parsed);
-            } catch (final IllegalArgumentException e) {
-                throw new ParseException("AllowedIPs", allowedIps, e);
+                for (final String allowedIp : Attribute.split(allowedIps))
+                    addAllowedIp(InetNetwork.parse(allowedIp));
+                return this;
+            } catch (final ParseException e) {
+                throw new BadConfigException(Section.PEER, Location.ALLOWED_IPS, e);
             }
         }
 
-        public Builder parseEndpoint(final String endpoint) throws ParseException {
+        public Builder parseEndpoint(final String endpoint) throws BadConfigException {
             try {
                 return setEndpoint(InetEndpoint.parse(endpoint));
-            } catch (final IllegalArgumentException e) {
-                throw new ParseException("Endpoint", endpoint, e);
+            } catch (final ParseException e) {
+                throw new BadConfigException(Section.PEER, Location.ENDPOINT, e);
             }
         }
 
-        public Builder parsePersistentKeepalive(final String persistentKeepalive) throws ParseException {
+        public Builder parsePersistentKeepalive(final String persistentKeepalive)
+                throws BadConfigException {
             try {
                 return setPersistentKeepalive(Integer.parseInt(persistentKeepalive));
-            } catch (final IllegalArgumentException e) {
-                throw new ParseException("PersistentKeepalive", persistentKeepalive, e);
+            } catch (final NumberFormatException e) {
+                throw new BadConfigException(Section.PEER, Location.PERSISTENT_KEEPALIVE,
+                        persistentKeepalive, e);
             }
         }
 
-        public Builder parsePreSharedKey(final String preSharedKey) throws ParseException {
+        public Builder parsePreSharedKey(final String preSharedKey) throws BadConfigException {
             try {
                 return setPreSharedKey(Key.fromBase64(preSharedKey));
-            } catch (final Key.KeyFormatException e) {
-                throw new ParseException("PresharedKey", preSharedKey, e);
+            } catch (final KeyFormatException e) {
+                throw new BadConfigException(Section.PEER, Location.PRE_SHARED_KEY, e);
             }
         }
 
-        public Builder parsePublicKey(final String publicKey) throws ParseException {
+        public Builder parsePublicKey(final String publicKey) throws BadConfigException {
             try {
                 return setPublicKey(Key.fromBase64(publicKey));
-            } catch (final Key.KeyFormatException e) {
-                throw new ParseException("PublicKey", publicKey, e);
+            } catch (final KeyFormatException e) {
+                throw new BadConfigException(Section.PEER, Location.PUBLIC_KEY, e);
             }
         }
 
@@ -277,9 +283,11 @@ public final class Peer {
             return this;
         }
 
-        public Builder setPersistentKeepalive(final int persistentKeepalive) {
+        public Builder setPersistentKeepalive(final int persistentKeepalive)
+                throws BadConfigException {
             if (persistentKeepalive < 0 || persistentKeepalive > MAX_PERSISTENT_KEEPALIVE)
-                throw new IllegalArgumentException("Invalid value for PersistentKeepalive");
+                throw new BadConfigException(Section.PEER, Location.PERSISTENT_KEEPALIVE,
+                        Reason.INVALID_VALUE, String.valueOf(persistentKeepalive));
             this.persistentKeepalive = persistentKeepalive == 0 ?
                     Optional.empty() : Optional.of(persistentKeepalive);
             return this;
diff --git a/app/src/main/java/com/wireguard/crypto/Key.java b/app/src/main/java/com/wireguard/crypto/Key.java
index 85146794..ded9941e 100644
--- a/app/src/main/java/com/wireguard/crypto/Key.java
+++ b/app/src/main/java/com/wireguard/crypto/Key.java
@@ -5,6 +5,9 @@
 
 package com.wireguard.crypto;
 
+import com.wireguard.crypto.KeyFormatException.Type;
+
+import java.security.SecureRandom;
 import java.util.Arrays;
 
 /**
@@ -83,10 +86,10 @@ public final class Key {
      * @param str the base64 string representation of a WireGuard key
      * @return the decoded key encapsulated in an immutable container
      */
-    public static Key fromBase64(final String str) {
+    public static Key fromBase64(final String str) throws KeyFormatException {
         final char[] input = str.toCharArray();
         if (input.length != Format.BASE64.length || input[Format.BASE64.length - 1] != '=')
-            throw new KeyFormatException(Format.BASE64);
+            throw new KeyFormatException(Format.BASE64, Type.LENGTH);
         final byte[] key = new byte[Format.BINARY.length];
         int i;
         int ret = 0;
@@ -109,7 +112,7 @@ public final class Key {
         key[i * 3 + 1] = (byte) ((val >>> 8) & 0xff);
 
         if (ret != 0)
-            throw new KeyFormatException(Format.BASE64);
+            throw new KeyFormatException(Format.BASE64, Type.CONTENTS);
         return new Key(key);
     }
 
@@ -120,9 +123,9 @@ public final class Key {
      * @param bytes an array of bytes containing a WireGuard key in binary format
      * @return the key encapsulated in an immutable container
      */
-    public static Key fromBytes(final byte[] bytes) {
+    public static Key fromBytes(final byte[] bytes) throws KeyFormatException {
         if (bytes.length != Format.BINARY.length)
-            throw new KeyFormatException(Format.BINARY);
+            throw new KeyFormatException(Format.BINARY, Type.LENGTH);
         return new Key(bytes);
     }
 
@@ -133,10 +136,10 @@ public final class Key {
      * @param str the hexadecimal string representation of a WireGuard key
      * @return the decoded key encapsulated in an immutable container
      */
-    public static Key fromHex(final String str) {
+    public static Key fromHex(final String str) throws KeyFormatException {
         final char[] input = str.toCharArray();
         if (input.length != Format.HEX.length)
-            throw new KeyFormatException(Format.HEX);
+            throw new KeyFormatException(Format.HEX, Type.LENGTH);
         final byte[] key = new byte[Format.BINARY.length];
         int ret = 0;
         for (int i = 0; i < key.length; ++i) {
@@ -167,11 +170,38 @@ public final class Key {
             key[i] = (byte) (cAcc | cVal);
         }
         if (ret != 0)
-            throw new KeyFormatException(Format.HEX);
+            throw new KeyFormatException(Format.HEX, Type.CONTENTS);
         return new Key(key);
     }
 
     /**
+     * Generates a private key using the system's {@link SecureRandom} number generator.
+     *
+     * @return a well-formed random private key
+     */
+    static Key generatePrivateKey() {
+        final SecureRandom secureRandom = new SecureRandom();
+        final byte[] privateKey = new byte[Format.BINARY.getLength()];
+        secureRandom.nextBytes(privateKey);
+        privateKey[0] &= 248;
+        privateKey[31] &= 127;
+        privateKey[31] |= 64;
+        return new Key(privateKey);
+    }
+
+    /**
+     * Generates a public key from an existing private key.
+     *
+     * @param privateKey a private key
+     * @return a well-formed public key that corresponds to the supplied private key
+     */
+    static Key generatePublicKey(final Key privateKey) {
+        final byte[] publicKey = new byte[Format.BINARY.getLength()];
+        Curve25519.eval(publicKey, 0, privateKey.getBytes(), null);
+        return new Key(publicKey);
+    }
+
+    /**
      * Returns the key as an array of bytes.
      *
      * @return an array of bytes containing the raw binary key
@@ -236,20 +266,4 @@ public final class Key {
         }
     }
 
-    /**
-     * An exception thrown when attempting to parse an invalid key (too short, too long, or byte
-     * data inappropriate for the format). The format being parsed can be accessed with the
-     * {@link #getFormat} method.
-     */
-    public static final class KeyFormatException extends RuntimeException {
-        private final Format format;
-
-        private KeyFormatException(final Format format) {
-            this.format = format;
-        }
-
-        public Format getFormat() {
-            return format;
-        }
-    }
 }
diff --git a/app/src/main/java/com/wireguard/crypto/KeyFormatException.java b/app/src/main/java/com/wireguard/crypto/KeyFormatException.java
new file mode 100644
index 00000000..b44297d1
--- /dev/null
+++ b/app/src/main/java/com/wireguard/crypto/KeyFormatException.java
@@ -0,0 +1,34 @@
+/*
+ * Copyright © 2018 WireGuard LLC. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.wireguard.crypto;
+
+/**
+ * An exception thrown when attempting to parse an invalid key (too short, too long, or byte
+ * data inappropriate for the format). The format being parsed can be accessed with the
+ * {@link #getFormat} method.
+ */
+public final class KeyFormatException extends Exception {
+    private final Key.Format format;
+    private final Type type;
+
+    KeyFormatException(final Key.Format format, final Type type) {
+        this.format = format;
+        this.type = type;
+    }
+
+    public Key.Format getFormat() {
+        return format;
+    }
+
+    public Type getType() {
+        return type;
+    }
+
+    public enum Type {
+        CONTENTS,
+        LENGTH
+    }
+}
diff --git a/app/src/main/java/com/wireguard/crypto/KeyPair.java b/app/src/main/java/com/wireguard/crypto/KeyPair.java
index 2b2bf564..2e771edc 100644
--- a/app/src/main/java/com/wireguard/crypto/KeyPair.java
+++ b/app/src/main/java/com/wireguard/crypto/KeyPair.java
@@ -5,8 +5,6 @@
 
 package com.wireguard.crypto;
 
-import java.security.SecureRandom;
-
 /**
  * Represents a Curve25519 key pair as used by WireGuard.
  * <p>
@@ -20,7 +18,7 @@ public class KeyPair {
      * Creates a key pair using a newly-generated private key.
      */
     public KeyPair() {
-        this(generatePrivateKey());
+        this(Key.generatePrivateKey());
     }
 
     /**
@@ -30,35 +28,7 @@ public class KeyPair {
      */
     public KeyPair(final Key privateKey) {
         this.privateKey = privateKey;
-        publicKey = generatePublicKey(privateKey);
-    }
-
-    /**
-     * Generates a private key using the system's {@link SecureRandom} number generator.
-     *
-     * @return a well-formed random private key
-     */
-    @SuppressWarnings("MagicNumber")
-    private static Key generatePrivateKey() {
-        final SecureRandom secureRandom = new SecureRandom();
-        final byte[] privateKey = new byte[Key.Format.BINARY.getLength()];
-        secureRandom.nextBytes(privateKey);
-        privateKey[0] &= 248;
-        privateKey[31] &= 127;
-        privateKey[31] |= 64;
-        return Key.fromBytes(privateKey);
-    }
-
-    /**
-     * Generates a public key from an existing private key.
-     *
-     * @param privateKey a private key
-     * @return a well-formed public key that corresponds to the supplied private key
-     */
-    private static Key generatePublicKey(final Key privateKey) {
-        final byte[] publicKey = new byte[Key.Format.BINARY.getLength()];
-        Curve25519.eval(publicKey, 0, privateKey.getBytes(), null);
-        return Key.fromBytes(publicKey);
+        publicKey = Key.generatePublicKey(privateKey);
     }
 
     /**