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1   /*
2    * Copyright 2016 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   https://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.handler.codec.smtp;
17  
18  import io.netty.buffer.ByteBuf;
19  import io.netty.buffer.ByteBufUtil;
20  import io.netty.buffer.Unpooled;
21  import io.netty.channel.ChannelHandlerContext;
22  import io.netty.handler.codec.MessageToMessageEncoder;
23  import io.netty.util.internal.UnstableApi;
24  
25  import java.util.Iterator;
26  import java.util.List;
27  import java.util.RandomAccess;
28  
29  /**
30   * Encoder for SMTP requests.
31   */
32  @UnstableApi
33  public final class SmtpRequestEncoder extends MessageToMessageEncoder<Object> {
34      private static final int CRLF_SHORT = ('\r' << 8) | '\n';
35      private static final byte SP = ' ';
36      private static final ByteBuf DOT_CRLF_BUFFER = Unpooled.unreleasableBuffer(
37              Unpooled.directBuffer(3).writeByte('.').writeByte('\r').writeByte('\n')).asReadOnly();
38  
39      private boolean contentExpected;
40  
41      @Override
42      public boolean acceptOutboundMessage(Object msg) throws Exception {
43          return msg instanceof SmtpRequest || msg instanceof SmtpContent;
44      }
45  
46      @Override
47      protected void encode(ChannelHandlerContext ctx, Object msg, List<Object> out) throws Exception {
48          if (msg instanceof SmtpRequest) {
49              final SmtpRequest req = (SmtpRequest) msg;
50              if (contentExpected) {
51                  if (req.command().equals(SmtpCommand.RSET)) {
52                      contentExpected = false;
53                  } else {
54                      throw new IllegalStateException("SmtpContent expected");
55                  }
56              }
57              boolean release = true;
58              final ByteBuf buffer = ctx.alloc().buffer();
59              try {
60                  req.command().encode(buffer);
61                  boolean notEmpty = req.command() != SmtpCommand.EMPTY;
62                  writeParameters(req.parameters(), buffer, notEmpty);
63                  ByteBufUtil.writeShortBE(buffer, CRLF_SHORT);
64                  out.add(buffer);
65                  release = false;
66                  if (req.command().isContentExpected()) {
67                      contentExpected = true;
68                  }
69              } finally {
70                  if (release) {
71                      buffer.release();
72                  }
73              }
74          }
75  
76          if (msg instanceof SmtpContent) {
77              if (!contentExpected) {
78                  throw new IllegalStateException("No SmtpContent expected");
79              }
80              final ByteBuf content = ((SmtpContent) msg).content();
81              out.add(content.retain());
82              if (msg instanceof LastSmtpContent) {
83                  out.add(DOT_CRLF_BUFFER.retainedDuplicate());
84                  contentExpected = false;
85              }
86          }
87      }
88  
89      private static void writeParameters(List<CharSequence> parameters, ByteBuf out, boolean commandNotEmpty) {
90          if (parameters.isEmpty()) {
91              return;
92          }
93          if (commandNotEmpty) {
94              out.writeByte(SP);
95          }
96          if (parameters instanceof RandomAccess) {
97              final int sizeMinusOne = parameters.size() - 1;
98              for (int i = 0; i < sizeMinusOne; i++) {
99                  ByteBufUtil.writeAscii(out, parameters.get(i));
100                 out.writeByte(SP);
101             }
102             ByteBufUtil.writeAscii(out, parameters.get(sizeMinusOne));
103         } else {
104             final Iterator<CharSequence> params = parameters.iterator();
105             for (;;) {
106                 ByteBufUtil.writeAscii(out, params.next());
107                 if (params.hasNext()) {
108                     out.writeByte(SP);
109                 } else {
110                     break;
111                 }
112             }
113         }
114     }
115 }