core/src/main/java/com/att/cadi/BufferedServletInputStream.java

   1 /*******************************************************************************\r
   2  * ============LICENSE_START====================================================\r
   3  * * org.onap.aai\r
   4  * * ===========================================================================\r
   5  * * Copyright © 2017 AT&T Intellectual Property. All rights reserved.\r
   6  * * Copyright © 2017 Amdocs\r
   7  * * ===========================================================================\r
   8  * * Licensed under the Apache License, Version 2.0 (the "License");\r
   9  * * you may not use this file except in compliance with the License.\r
  10  * * You may obtain a copy of the License at\r
  11  * * \r
  12  *  *      http://www.apache.org/licenses/LICENSE-2.0\r
  13  * * \r
  14  *  * Unless required by applicable law or agreed to in writing, software\r
  15  * * distributed under the License is distributed on an "AS IS" BASIS,\r
  16  * * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\r
  17  * * See the License for the specific language governing permissions and\r
  18  * * limitations under the License.\r
  19  * * ============LICENSE_END====================================================\r
  20  * *\r
  21  * * ECOMP is a trademark and service mark of AT&T Intellectual Property.\r
  22  * *\r
  23  ******************************************************************************/\r
  24 package com.att.cadi;\r
  25 \r
  26 import java.io.IOException;\r
  27 import java.io.InputStream;\r
  28 \r
  29 import javax.servlet.ServletInputStream;\r
  30 \r
  31 /**\r
  32  * BufferedServletInputStream\r
  33  * \r
  34  * There are cases in brain-dead middleware (SOAP) where they store routing information in the content.\r
  35  * \r
  36  * In HTTP, this requires reading the content from the InputStream which, of course, cannot be re-read.\r
  37  * \r
  38  * BufferedInputStream exists to implement the "Mark" protocols for Streaming, which will enable being \r
  39  * re-read.  Unfortunately, J2EE chose to require a "ServletInputStream" as an abstract class, rather than\r
  40  * an interface, which requires we create a delegating pattern, rather than the preferred inheriting pattern. \r
  41  * \r
  42  * Unfortunately, the standard "BufferedInputStream" cannot be used, because it simply creates a byte array\r
  43  * in the "mark(int)" method of that size.  This is not appropriate for this application, because the Header \r
  44  * can be potentially huge, and if a buffer was allocated to accommodate all possibilities, the cost of memory \r
  45  * allocation would be too large for high performance transactions.\r
  46  *\r
  47  * \r
  48  *\r
  49  */\r
  50 public class BufferedServletInputStream extends ServletInputStream {\r
  51         private static final int NONE = 0;\r
  52         private static final int STORE = 1;\r
  53         private static final int READ = 2;\r
  54         \r
  55         private InputStream is;\r
  56         private int state = NONE;\r
  57         private Capacitor capacitor;\r
  58 \r
  59         public BufferedServletInputStream(InputStream is) {\r
  60                 this.is = is;\r
  61                 capacitor = null;\r
  62         }\r
  63 \r
  64 \r
  65         // @Override\r
  66         public int read() throws IOException {\r
  67                 int value=-1;\r
  68                 if(capacitor==null) {\r
  69                         value=is.read();\r
  70                 } else {\r
  71                         switch(state) {\r
  72                                 case STORE:\r
  73                                         value = is.read();\r
  74                                         if(value>=0) {\r
  75                                                 capacitor.put((byte)value);\r
  76                                         }\r
  77                                         break;\r
  78                                 case READ:\r
  79                                         value = capacitor.read();\r
  80                                         if(value<0) {\r
  81                                                 capacitor.done();\r
  82                                                 capacitor=null; // all done with buffer\r
  83                                                 value = is.read();\r
  84                                         }\r
  85                         }\r
  86                 } \r
  87                 return value;\r
  88         }\r
  89 \r
  90         // @Override\r
  91         public int read(byte[] b) throws IOException {\r
  92                 return read(b,0,b.length);\r
  93         }\r
  94 \r
  95 \r
  96         // @Override\r
  97         public int read(byte[] b, int off, int len) throws IOException {\r
  98                 int count = -1;\r
  99                 if(capacitor==null) {\r
 100                         count = is.read(b,off,len);\r
 101                 } else {\r
 102                         switch(state) {\r
 103                                 case STORE:\r
 104                                         count = is.read(b, off, len);\r
 105                                         if(count>0) {\r
 106                                                 capacitor.put(b, off, count);\r
 107                                         }\r
 108                                         break;\r
 109                                 case READ:\r
 110                                         count = capacitor.read(b, off, len);\r
 111 //                                      System.out.println("Capacitor read " + count);\r
 112                                         if(count<=0) {\r
 113                                                 capacitor.done();\r
 114                                                 capacitor=null; // all done with buffer\r
 115                                         }\r
 116                                         if(count<len) {\r
 117                                                 int temp = is.read(b, count, len-count);\r
 118 //                                              System.out.println("Capacitor done, stream read " + temp);\r
 119                                                 if(temp>0) { // watch for -1\r
 120                                                         count+=temp;\r
 121                                                 } else {\r
 122                                                         if(count<=0)count = temp; // must account for Stream coming back -1  \r
 123                                                 }\r
 124                                         }\r
 125                                         break;\r
 126                         }\r
 127                 }\r
 128 //              System.out.println("read reports " + count);\r
 129                 return count;\r
 130         }\r
 131 \r
 132         // @Override\r
 133         public long skip(long n) throws IOException {\r
 134                 long skipped = capacitor.skip(n);\r
 135                 if(skipped<n) {\r
 136                         skipped += is.skip(n-skipped);\r
 137                 }\r
 138                 return skipped;\r
 139         }\r
 140 \r
 141 \r
 142         // @Override\r
 143         public int available() throws IOException {\r
 144                 int count = is.available();\r
 145                 if(capacitor!=null)count+=capacitor.available();\r
 146                 return count;           \r
 147         }\r
 148         \r
 149         /**\r
 150          * Return just amount buffered (for debugging purposes, mostly)\r
 151          * @return\r
 152          */\r
 153         public int buffered() {\r
 154                 return capacitor.available();\r
 155         }\r
 156 \r
 157 \r
 158         // @Override\r
 159         public void close() throws IOException {\r
 160                 if(capacitor!=null) {\r
 161                         capacitor.done();\r
 162                         capacitor=null;\r
 163                 }\r
 164                 is.close();\r
 165         }\r
 166 \r
 167 \r
 168         /**\r
 169          * Note: Readlimit is ignored in this implementation, because the need was for unknown buffer size which wouldn't \r
 170          * require allocating and dumping huge chunks of memory every use, or risk overflow.\r
 171          */\r
 172         // @Override\r
 173         public synchronized void mark(int readlimit) {\r
 174                 switch(state) {\r
 175                         case NONE:\r
 176                                 capacitor = new Capacitor();\r
 177                                 break;\r
 178                         case READ:\r
 179                                 capacitor.done();\r
 180                                 break;\r
 181                         // ignore case STORE:\r
 182                 }\r
 183                 state = STORE;\r
 184         }\r
 185 \r
 186 \r
 187         /**\r
 188          * Reset Stream\r
 189          * \r
 190          * Calling this twice is not supported in typical Stream situations, but it is allowed in this service.  The caveat is that it can only reset\r
 191          * the data read in since Mark has been called.  The data integrity is only valid if you have not continued to read past what is stored.\r
 192          *  \r
 193          */\r
 194         // @Override\r
 195         public synchronized void reset() throws IOException {\r
 196                 switch(state) {\r
 197                         case STORE:\r
 198                                 capacitor.setForRead();\r
 199                                 state = READ;\r
 200                                 break;\r
 201                         case READ:\r
 202                                 capacitor.reset();\r
 203                                 break;\r
 204 //                              throw new IOException("InputStream is already in READ state");\r
 205                         case NONE: \r
 206                                 throw new IOException("InputStream has not been marked");\r
 207                 }\r
 208         }\r
 209 \r
 210 \r
 211         // @Override\r
 212         public boolean markSupported() {\r
 213                 return true;\r
 214         }\r
 215 }\r