android: Add simple utility class to generate settings_t compatible config snippets

src/frontends/android/src/org/strongswan/android/utils/SettingsWriter.java

@@ -0,0 +1,160 @@
+/*
+ * Copyright (C) 2015 Tobias Brunner
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+package org.strongswan.android.utils;
+
+import java.util.Arrays;
+import java.util.LinkedHashMap;
+import java.util.Map.Entry;
+import java.util.regex.Pattern;
+
+
+/**
+ * Simple generator for data/files that may be parsed by libstrongswan's
+ * settings_t class.
+ */
+public class SettingsWriter
+{
+	/**
+	 * Top-level section
+	 */
+	private final SettingsSection mTop = new SettingsSection();
+
+	/**
+	 * Set a string value
+	 * @param key
+	 * @param value
+	 * @return the writer
+	 */
+	public SettingsWriter setValue(String key, String value)
+	{
+		Pattern pattern = Pattern.compile("[^#{}=\"\\n\\t ]+");
+		if (key == null || !pattern.matcher(key).matches())
+		{
+			return this;
+		}
+		String[] keys = key.split("\\.");
+		SettingsSection section = mTop;
+		section = findOrCreateSection(Arrays.copyOfRange(keys, 0, keys.length-1));
+		section.Settings.put(keys[keys.length-1], value);
+		return this;
+	}
+
+	/**
+	 * Set an integer value
+	 * @param key
+	 * @param value
+	 * @return the writer
+	 */
+	public SettingsWriter setValue(String key, Integer value)
+	{
+		return setValue(key, value == null ? null : value.toString());
+	}
+
+	/**
+	 * Set a boolean value
+	 * @param key
+	 * @param value
+	 * @return the writer
+	 */
+	public SettingsWriter setValue(String key, Boolean value)
+	{
+		return setValue(key, value == null ? null : value ? "1" : "0");
+	}
+
+	/**
+	 * Serializes the settings to a string in the format understood by
+	 * libstrongswan's settings_t parser.
+	 * @return serialized settings
+	 */
+	public String serialize()
+	{
+		StringBuilder builder = new StringBuilder();
+		serializeSection(mTop, builder);
+		return builder.toString();
+	}
+
+	/**
+	 * Serialize the settings in a section and recursively serialize sub-sections
+	 * @param section
+	 * @param builder
+	 */
+	private void serializeSection(SettingsSection section, StringBuilder builder)
+	{
+		for (Entry<String, String> setting : section.Settings.entrySet())
+		{
+			builder.append(setting.getKey()).append('=');
+			if (setting.getValue() != null)
+			{
+				builder.append("\"").append(escapeValue(setting.getValue())).append("\"");
+			}
+			builder.append('\n');
+		}
+
+		for (Entry<String, SettingsSection> subsection : section.Sections.entrySet())
+		{
+			builder.append(subsection.getKey()).append(" {\n");
+			serializeSection(subsection.getValue(), builder);
+			builder.append("}\n");
+		}
+	}
+
+	/**
+	 * Escape value so it may be wrapped in "
+	 * @param value
+	 * @return
+	 */
+	private String escapeValue(String value)
+	{
+		return value.replace("\"", "\\\"");
+	}
+
+	/**
+	 * Find or create the nested sections with the given names
+	 * @param sections list of section names
+	 * @return final section
+	 */
+	private SettingsSection findOrCreateSection(String[] sections)
+	{
+		SettingsSection section = mTop;
+		for (String name : sections)
+		{
+			SettingsSection subsection = section.Sections.get(name);
+			if (subsection == null)
+			{
+				subsection = new SettingsSection();
+				section.Sections.put(name, subsection);
+			}
+			section = subsection;
+		}
+		return section;
+	}
+
+	/**
+	 * A section containing sub-sections and settings.
+	 */
+	private class SettingsSection
+	{
+		/**
+		 * Assigned key/value pairs
+		 */
+		LinkedHashMap<String,String> Settings = new LinkedHashMap<String, String>();
+
+		/**
+		 * Assigned sub-sections
+		 */
+		LinkedHashMap<String,SettingsSection> Sections = new LinkedHashMap<String, SettingsWriter.SettingsSection>();
+	}
+}