1 files changed, 109 insertions, 0 deletions
diff --git a/app/src/main/java/com/wireguard/android/util/RootShell.java b/app/src/main/java/com/wireguard/android/util/RootShell.java
new file mode 100644
index 00000000..35f4735b
--- /dev/null
+++ b/app/src/main/java/com/wireguard/android/util/RootShell.java
@@ -0,0 +1,109 @@
+package com.wireguard.android.util;
+
+import android.content.Context;
+import android.system.OsConstants;
+import android.util.Log;
+
+import com.wireguard.android.Application.ApplicationContext;
+import com.wireguard.android.Application.ApplicationScope;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import javax.inject.Inject;
+
+/**
+ * Helper class for running commands as root.
+ */
+
+@ApplicationScope
+public class RootShell {
+    private static final Pattern ERRNO_EXTRACTOR = Pattern.compile("error=(\\d+)");
+    /**
+     * Setup commands that are run at the beginning of each root shell. The trap command ensures
+     * access to the return value of the last command, since su itself always exits with 0.
+     */
+    private static final String TAG = "WireGuard/RootShell";
+    private static final String[][] libraryNamedExecutables = {
+            {"libwg.so", "wg"},
+            {"libwg-quick.so", "wg-quick"}
+    };
+
+    private final String preamble;
+
+    @Inject
+    public RootShell(@ApplicationContext final Context context) {
+        final String binDir = context.getCacheDir().getPath() + "/bin";
+        final String tmpDir = context.getCacheDir().getPath() + "/tmp";
+        final String libDir = context.getApplicationInfo().nativeLibraryDir;
+
+        new File(binDir).mkdirs();
+        new File(tmpDir).mkdirs();
+
+        StringBuilder builder = new StringBuilder();
+        for (final String[] libraryNamedExecutable : libraryNamedExecutables) {
+            final String arg1 = "'" + libDir + "/" + libraryNamedExecutable[0] + "'";
+            final String arg2 = "'" + binDir + "/" + libraryNamedExecutable[1] + "'";
+            builder.append(String.format("[ %s -ef %s ] || ln -sf %s %s || exit 31;", arg1, arg2, arg1, arg2));
+        }
+        builder.append(String.format("export PATH=\"%s:$PATH\" TMPDIR=\"%s\";", binDir, tmpDir));
+
+        preamble = builder.toString();
+    }
+
+    /**
+     * Run a command in a root shell.
+     *
+     * @param output  Lines read from stdout are appended to this list. Pass null if the
+     *                output from the shell is not important.
+     * @param command Command to run as root.
+     * @return The exit value of the last command run, or -1 if there was an internal error.
+     */
+    public int run(final List<String> output, final String command) {
+        int exitValue = -1;
+        try {
+            final ProcessBuilder builder = new ProcessBuilder();
+            builder.environment().put("LANG", "C");
+            builder.command("su", "-c", preamble + command);
+            final Process process = builder.start();
+            Log.d(TAG, "Running: " + command);
+            final InputStream stdout = process.getInputStream();
+            final InputStream stderr = process.getErrorStream();
+            final BufferedReader stdoutReader =
+                    new BufferedReader(new InputStreamReader(stdout, StandardCharsets.UTF_8));
+            final BufferedReader stderrReader =
+                    new BufferedReader(new InputStreamReader(stderr, StandardCharsets.UTF_8));
+            String line;
+            while ((line = stdoutReader.readLine()) != null) {
+                if (output != null)
+                    output.add(line);
+                Log.v(TAG, "stdout: " + line);
+            }
+            int linesOfStderr = 0;
+            String stderrLast = null;
+            while ((line = stderrReader.readLine()) != null) {
+                ++linesOfStderr;
+                stderrLast = line;
+                Log.v(TAG, "stderr: " + line);
+            }
+            exitValue = process.waitFor();
+            process.destroy();
+            if (exitValue == 1 && linesOfStderr == 1 && stderrLast.equals("Permission denied"))
+                exitValue = OsConstants.EACCES;
+            Log.d(TAG, "Exit status: " + exitValue);
+        } catch (IOException | InterruptedException e) {
+            Log.w(TAG, "Session failed with exception", e);
+            final Matcher match = ERRNO_EXTRACTOR.matcher(e.toString());
+            if (match.find())
+                exitValue = Integer.valueOf(match.group(1));
+        }
+        return exitValue;
+    }
+}