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| * distributed with this work for additional information * |
| * regarding copyright ownership. The ASF licenses this file * |
| * to you under the Apache License, Version 2.0 (the * |
| * "License"); you may not use this file except in compliance * |
| * with the License. You may obtain a copy of the License at * |
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| * http://www.apache.org/licenses/LICENSE-2.0 * |
| * * |
| * Unless required by applicable law or agreed to in writing, * |
| * software distributed under the License is distributed on an * |
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| * under the License. * |
| ****************************************************************/ |
| package org.apache.james.protocols.netty; |
| |
| import java.nio.charset.StandardCharsets; |
| import java.util.List; |
| import java.util.Locale; |
| import java.util.Optional; |
| |
| import org.apache.james.protocols.api.CommandDetectionSession; |
| import org.jboss.netty.buffer.ChannelBuffer; |
| import org.jboss.netty.channel.Channel; |
| import org.jboss.netty.channel.ChannelHandlerContext; |
| import org.jboss.netty.channel.ChannelPipeline; |
| import org.jboss.netty.handler.codec.frame.LineBasedFrameDecoder; |
| |
| import com.google.common.base.CharMatcher; |
| import com.google.common.base.Splitter; |
| |
| public class AllButStartTlsLineBasedChannelHandler extends LineBasedFrameDecoder { |
| private static final Boolean FAIL_FAST = true; |
| private static final CharMatcher CRLF_MATCHER = CharMatcher.anyOf("\r\n"); |
| private static final Splitter CRLF_SPLITTER = Splitter.on(CRLF_MATCHER).omitEmptyStrings(); |
| |
| private final ChannelPipeline pipeline; |
| private final String pattern; |
| |
| public AllButStartTlsLineBasedChannelHandler(ChannelPipeline pipeline, int maxFrameLength, boolean stripDelimiter, String pattern) { |
| super(maxFrameLength, stripDelimiter, !FAIL_FAST); |
| this.pipeline = pipeline; |
| this.pattern = pattern; |
| } |
| |
| @Override |
| protected Object decode(ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer) throws Exception { |
| CommandDetectionSession session = retrieveSession(ctx, channel); |
| |
| if (session == null || session.needsCommandInjectionDetection()) { |
| boolean startTlsInFlight = Optional.ofNullable(ctx.getChannel().getAttachment()) |
| .filter(Boolean.class::isInstance) |
| .map(Boolean.class::cast) |
| .orElse(false); |
| String trimedLowerCasedInput = readAll(buffer).trim().toLowerCase(Locale.US); |
| if (hasCommandInjection(trimedLowerCasedInput) || startTlsInFlight) { |
| throw new CommandInjectionDetectedException(); |
| } |
| // Prevents further reads on this channel to avoid race conditions |
| // Framer can accept IMAP requests sent concurrently while the channel is |
| // not yet encrypted allowing man-in-the-middle attacks relying on race conditions |
| // Disabling auto-read when framing STARTTLS prevents accepting other frames until STARTTLS |
| // is fully active. |
| if (hasStartTLS(trimedLowerCasedInput)) { |
| ctx.getChannel().setAttachment(true); |
| } |
| } |
| return super.decode(ctx, channel, buffer); |
| } |
| |
| protected boolean hasStartTLS(String trimedLowerCasedInput) { |
| List<String> parts = CRLF_SPLITTER.splitToList(trimedLowerCasedInput); |
| |
| return parts.stream().anyMatch(s -> s.equalsIgnoreCase(pattern)); |
| } |
| |
| protected CommandDetectionSession retrieveSession(ChannelHandlerContext ctx, Channel channel) { |
| return (CommandDetectionSession) pipeline.getContext(HandlerConstants.CORE_HANDLER).getAttachment(); |
| } |
| |
| private String readAll(ChannelBuffer buffer) { |
| return buffer.toString(StandardCharsets.US_ASCII); |
| } |
| |
| private boolean hasCommandInjection(String trimedLowerCasedInput) { |
| List<String> parts = CRLF_SPLITTER.splitToList(trimedLowerCasedInput); |
| |
| return hasInvalidStartTlsPart(parts) || multiPartsAndOneStartTls(parts); |
| } |
| |
| protected boolean multiPartsAndOneStartTls(List<String> parts) { |
| return parts.stream() |
| .anyMatch(line -> line.startsWith(pattern)) && parts.size() > 1; |
| } |
| |
| protected boolean hasInvalidStartTlsPart(List<String> parts) { |
| return parts.stream() |
| .anyMatch(line -> line.startsWith(pattern) && !line.endsWith(pattern)); |
| } |
| } |