message automod rules

src/main/java/net/discordjug/javabot/RuntimeHintsConfiguration.java

@@ -9,6 +9,7 @@
 import net.discordjug.javabot.data.config.SystemsConfig.ApiConfig;
 import net.discordjug.javabot.data.config.guild.HelpConfig;
 import net.discordjug.javabot.data.config.guild.MessageCacheConfig;
+import net.discordjug.javabot.data.config.guild.MessageRule;
 import net.discordjug.javabot.data.config.guild.MetricsConfig;
 import net.discordjug.javabot.data.config.guild.ModerationConfig;
 import net.discordjug.javabot.data.config.guild.QOTWConfig;
@@ -34,7 +35,7 @@
 @RegisterReflectionForBinding({
 		//register config classes for reflection
 		BotConfig.class, GuildConfig.class, GuildConfigItem.class, SystemsConfig.class, ApiConfig.class,
-		HelpConfig.class, MessageCacheConfig.class, MetricsConfig.class, ModerationConfig.class, QOTWConfig.class, ServerLockConfig.class, StarboardConfig.class,
+		HelpConfig.class, MessageCacheConfig.class, MetricsConfig.class, ModerationConfig.class, QOTWConfig.class, ServerLockConfig.class, StarboardConfig.class,MessageRule.class, MessageRule.MessageAction.class,
 
 		//needs to be serialized for channel managers etc
 		PermOverrideData.class,

src/main/java/net/discordjug/javabot/data/config/GuildConfig.java

@@ -20,6 +20,7 @@
 import java.nio.file.Path;
 import java.util.List;
 import java.util.Optional;
+import java.util.regex.Pattern;
 
 /**
  * A collection of guild-specific configuration items, each of which represents
@@ -70,7 +71,9 @@ public GuildConfig(Guild guild, Path file) {
 	 * @throws UncheckedIOException if an IO error occurs.
 	 */
 	public static GuildConfig loadOrCreate(Guild guild, Path file) {
-		Gson gson = new GsonBuilder().create();
+		Gson gson = new GsonBuilder()
+				.registerTypeAdapter(Pattern.class, new PatternTypeAdapter())
+				.create();
 		GuildConfig config;
 		if (Files.exists(file)) {
 			try (BufferedReader reader = Files.newBufferedReader(file)) {
@@ -115,7 +118,11 @@ private void setGuild(Guild guild) {
 	 * Saves this config to its file path.
 	 */
 	public synchronized void flush() {
-		Gson gson = new GsonBuilder().serializeNulls().setPrettyPrinting().create();
+		Gson gson = new GsonBuilder()
+				.serializeNulls()
+				.setPrettyPrinting()
+				.registerTypeAdapter(Pattern.class, new PatternTypeAdapter())
+				.create();
 		try (BufferedWriter writer = Files.newBufferedWriter(this.file)) {
 			gson.toJson(this, writer);
 			writer.flush();

src/main/java/net/discordjug/javabot/data/config/PatternTypeAdapter.java

@@ -0,0 +1,35 @@
+package net.discordjug.javabot.data.config;
+
+import java.io.IOException;
+import java.util.regex.Pattern;
+
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
+import com.google.gson.stream.JsonWriter;
+
+/**
+ * A gson {@link TypeAdapter} that allows serializing and deserializing regex {@link Pattern}s.
+ */
+public class PatternTypeAdapter extends TypeAdapter<Pattern> {
+
+	@Override
+	public void write(JsonWriter writer, Pattern value) throws IOException {
+		if (value == null) {
+			writer.nullValue();
+			return;
+		}
+		writer.value(value.toString());
+	}
+
+	@Override
+	public Pattern read(JsonReader reader) throws IOException {
+		if (reader.peek() == JsonToken.NULL) {
+			reader.nextNull();
+			return null;
+		}
+		String value = reader.nextString();
+		return Pattern.compile(value);
+	}
+
+}

src/main/java/net/discordjug/javabot/data/config/guild/MessageRule.java

@@ -0,0 +1,54 @@
+package net.discordjug.javabot.data.config.guild;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.regex.Pattern;
+
+import lombok.Data;
+
+/**
+ * If a message matches all of the given requirements of a rule, the configured action is performed on the message.
+ */
+@Data
+public class MessageRule {
+	/**
+	 * Messages must match this regex for the rule to activate.
+	 */
+	private Pattern messageRegex;
+	/**
+	 * All attachments of the message must match this regex for the rule to activate.
+	 */
+	private Pattern attachmentNameRegex;
+	/**
+	 * The number of attachments must be greater than or equal to that field for the rule to activate.
+	 */
+	private int minAttachments = -1;
+	/**
+	 * The number of attachments must be less than or equal to that field for the rule to activate.
+	 */
+	private int maxAttachments = Integer.MAX_VALUE;
+	/**
+	 * At least one attachment must match at least one of the SHA hashes for the rule to activate.
+	 * If this set is empty, this condition is ignored.
+	 */
+	private Set<String> attachmentSHAs = new HashSet<>();
+
+	/**
+	 * The action to execute on the message.
+	 */
+	private MessageAction action = MessageAction.LOG;
+
+	/**
+	 * Enum for actions that can be performed on messages based on rules.
+	 */
+	public enum MessageAction {
+		/**
+		 * The message is logged to a channel.
+		 */
+		LOG,
+		/**
+		 * The message is deleted and logged to a channel.
+		 */
+		BLOCK
+	}
+}

src/main/java/net/discordjug/javabot/data/config/guild/ModerationConfig.java

@@ -8,6 +8,7 @@
 import net.dv8tion.jda.api.entities.channel.concrete.TextChannel;
 import net.dv8tion.jda.api.entities.channel.concrete.VoiceChannel;
 
+import java.util.ArrayList;
 import java.util.List;
 
 /**
@@ -98,12 +99,17 @@ public class ModerationConfig extends GuildConfigItem {
 	 * The ID of the voice channel template that lets users create their own voice channels.
 	 */
 	private long customVoiceChannelId;
-
+	
 	/**
 	 * Text that is sent to users when they're banned.
 	 */
 	private String banMessageText = "Looks like you've been banned from the Java Discord. If you want to appeal this decision please fill out our form at <https://airtable.com/shrp5V4H1U5TYOXyC>.";
 
+	/**
+	 * A list of rules that can result in a message being blocked or similar.
+	 */
+	private List<MessageRule> messageRules = new ArrayList<>();
+
 	public TextChannel getReportChannel() {
 		return this.getGuild().getTextChannelById(this.reportChannelId);
 	}

src/main/java/net/discordjug/javabot/data/h2db/message_cache/MessageCache.java

@@ -188,23 +188,31 @@ private void requestMessageAttachments(CachedMessage message) {
 		}
 	}
 
-	private EmbedBuilder buildMessageCacheEmbed(MessageChannel channel, User author, CachedMessage before) {
-		long epoch = IdCalculatorCommand.getTimestampFromId(before.getMessageId()) / 1000;
+	/**
+	 * Creates an {@link EmbedBuilder} with information about a cached message.
+	 * @param channel The channel the message was sent in.
+	 * @param author The author of the message.
+	 * @param message The message to extract the information from as a {@link CachedMessage}.
+	 * @param contentFieldName the name of the field containing the message content in the embed.
+	 * @return an {@link EmbedBuilder} with information about the message.
+	 */
+	public EmbedBuilder buildMessageCacheEmbed(MessageChannel channel, User author, CachedMessage message, String contentFieldName) {
+		long epoch = IdCalculatorCommand.getTimestampFromId(message.getMessageId()) / 1000;
 		return new EmbedBuilder()
 				.setAuthor(UserUtils.getUserTag(author), null, author.getEffectiveAvatarUrl())
 				.addField("Author", author.getAsMention(), true)
 				.addField("Channel", channel.getAsMention(), true)
 				.addField("Created at", String.format("<t:%s:F>", epoch), true)
-				.setFooter("ID: " + before.getMessageId());
+				.setFooter("ID: " + message.getMessageId())
+				.addField(contentFieldName,
+						message.getMessageContent().substring(0, Math.min(message.getMessageContent().length(), MessageEmbed.VALUE_MAX_LENGTH)),
+						false);
 	}
 
 	private MessageEmbed buildMessageEditEmbed(Guild guild, User author, MessageChannel channel, CachedMessage before, Message after) {
-		EmbedBuilder eb = buildMessageCacheEmbed(channel, author, before)
+		EmbedBuilder eb = buildMessageCacheEmbed(channel, author, before, "Before")
 				.setTitle("Message Edited")
 				.setColor(Responses.Type.WARN.getColor())
-				.addField("Before", before.getMessageContent().substring(0, Math.min(
-						before.getMessageContent().length(),
-						MessageEmbed.VALUE_MAX_LENGTH)), false)
 				.addField("After", after.getContentRaw().substring(0, Math.min(
 						after.getContentRaw().length(),
 						MessageEmbed.VALUE_MAX_LENGTH)), false);
@@ -226,13 +234,9 @@ private MessageEmbed buildMessageEditEmbed(Guild guild, User author, MessageChan
 	}
 
 	private MessageEmbed buildMessageDeleteEmbed(Guild guild, User author, MessageChannel channel, CachedMessage message) {
-		EmbedBuilder eb = buildMessageCacheEmbed(channel, author, message)
+		EmbedBuilder eb = buildMessageCacheEmbed(channel, author, message, "Message Content")
 				.setTitle("Message Deleted")
-				.setColor(Responses.Type.ERROR.getColor())
-				.addField("Message Content",
-						message.getMessageContent().substring(0, Math.min(
-								message.getMessageContent().length(),
-								MessageEmbed.VALUE_MAX_LENGTH)), false);
+				.setColor(Responses.Type.ERROR.getColor());
 		if (!message.getAttachments().isEmpty()) {
 			addAttachmentsToMessageBuilder(message, eb);
 		}

src/main/java/net/discordjug/javabot/listener/filter/MessageRuleFilter.java

@@ -0,0 +1,134 @@
+package net.discordjug.javabot.listener.filter;
+
+import java.io.IOException;
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.net.http.HttpResponse.BodyHandlers;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.time.Duration;
+import java.util.Base64;
+import java.util.List;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import lombok.RequiredArgsConstructor;
+import net.discordjug.javabot.data.config.BotConfig;
+import net.discordjug.javabot.data.config.PatternTypeAdapter;
+import net.discordjug.javabot.data.config.guild.MessageRule;
+import net.discordjug.javabot.data.config.guild.MessageRule.MessageAction;
+import net.discordjug.javabot.data.config.guild.ModerationConfig;
+import net.discordjug.javabot.data.h2db.message_cache.MessageCache;
+import net.discordjug.javabot.data.h2db.message_cache.model.CachedMessage;
+import net.discordjug.javabot.util.Checks;
+import net.discordjug.javabot.util.ExceptionLogger;
+import net.dv8tion.jda.api.EmbedBuilder;
+import net.dv8tion.jda.api.entities.Message.Attachment;
+import net.dv8tion.jda.api.entities.Message;
+import org.springframework.stereotype.Component;
+
+/**
+ * This {@link MessageFilter} acts on messages according to {@link MessageRule}s.
+ * If a message rule matches, the corresponding action is executed.
+ */
+@Component
+@RequiredArgsConstructor
+public class MessageRuleFilter implements MessageFilter {
+
+	private final BotConfig botConfig;
+	private final MessageCache messageCache;
+
+	@Override
+	public MessageModificationStatus processMessage(MessageContent content) {
+
+		ModerationConfig moderationConfig = botConfig.get(content.event().getGuild()).getModerationConfig();
+		List<MessageRule> messageRules = moderationConfig.getMessageRules();
+
+		MessageRule ruleToExecute = null;
+		for (MessageRule rule : messageRules) {
+			if (matches(content, rule)) {
+				if (ruleToExecute == null || rule.getAction() == MessageAction.BLOCK) {
+					ruleToExecute = rule;
+				}
+			}
+		}
+		MessageModificationStatus status = MessageModificationStatus.NOT_MODIFIED;
+		if (ruleToExecute != null) {
+			if (ruleToExecute.getAction() == MessageAction.BLOCK && !Checks.hasStaffRole(botConfig, content.event().getMember())) {
+				content.event().getMessage().delete()
+					.flatMap(_ -> content.event().getChannel().sendMessage(content.event().getAuthor().getAsMention() + " Your message has been deleted for moderative reasons. If you believe this happened by mistake, please contact the server staff."))
+					.delay(Duration.ofSeconds(60))
+					.flatMap(Message::delete)
+					.queue();
+				status = MessageModificationStatus.STOP_PROCESSING;
+			}
+			log(content, ruleToExecute, moderationConfig);
+		}
+
+		return status;
+	}
+
+	private void log(MessageContent content, MessageRule ruleToExecute, ModerationConfig moderationConfig) {
+		Gson gson = new GsonBuilder()
+				.serializeNulls()
+				.setPrettyPrinting()
+				.registerTypeAdapter(Pattern.class, new PatternTypeAdapter())
+				.create();
+		EmbedBuilder embed = messageCache.buildMessageCacheEmbed(
+				content.event().getMessage().getChannel(),
+				content.event().getMessage().getAuthor(),
+				CachedMessage.of(content.event().getMessage()), "Message content")
+			.setTitle("Message rule triggered")
+			.addField("Rule description", "```\n" + gson.toJson(ruleToExecute) + "\n```", false);
+		if (!content.attachments().isEmpty()) {
+			embed.addField("Attachment hashes", computeAttachmentDescription(content.attachments()), false);
+		}
+		content.event().getChannel().sendMessageEmbeds(embed.build()).queue();
+	}
+
+	private boolean matches(MessageContent content, MessageRule rule) {
+		if (rule.getMessageRegex() != null && !rule.getMessageRegex().matcher(content.messageText()).matches()) {
+			return false;
+		}
+		if (content.attachments().size() > rule.getMaxAttachments()) {
+			return false;
+		}
+		if (content.attachments().size() < rule.getMinAttachments()) {
+			return false;
+		}
+		boolean matchesSHA = rule.getAttachmentSHAs().isEmpty();
+		for (Attachment attachment : content.attachments()) {
+			if (rule.getAttachmentNameRegex() != null && !rule.getAttachmentNameRegex().matcher(attachment.getFileName()).matches()) {
+				return false;
+			}
+			if (!matchesSHA) {
+				if (rule.getAttachmentSHAs().contains(computeSHA(attachment))) {
+					matchesSHA = true;
+				}
+			}
+		}
+		return matchesSHA;
+	}
+
+	private String computeAttachmentDescription(List<Message.Attachment> attachments) {
+		return attachments.stream()
+				.map(attachment -> "- " + attachment.getUrl() + ": `" + computeSHA(attachment) + "`")
+				.collect(Collectors.joining("\n"));
+	}
+
+	private String computeSHA(Attachment attachment) {
+		try {
+			HttpResponse<byte[]> res = HttpClient.newHttpClient().send(HttpRequest.newBuilder(URI.create(attachment.getProxyUrl())).build(), BodyHandlers.ofByteArray());
+			MessageDigest digest = MessageDigest.getInstance("SHA-256");
+			byte[] hash = digest.digest(res.body());
+			return Base64.getEncoder().encodeToString(hash);
+		} catch (IOException | InterruptedException | NoSuchAlgorithmException e) {
+			ExceptionLogger.capture(e);
+			return "";
+		}
+	}
+}