Fixed info hash calculation, changed readme, added option to disable info hash calculation

Author: robothaver

README.md

@@ -17,7 +17,7 @@ A simple java library that allows you to read the contents of a torrent file.
         String pieces;
         boolean isSingleFile;
         boolean isPrivate;
-        String infoHash;
+        String infoHash; // null if computeInfoHash is set to false
 
         // Optional fields
         List<List<String>> announceList;

src/main/java/com/robothaver/torrentfileparser/TorrentFileParser.java

@@ -8,12 +8,14 @@
 
 public class TorrentFileParser {
     private final byte[] bytes;
+    private final boolean computeInfoHash;
     private int iterator = 0;
     private TorrentBuilder torrentBuilder = null;
     private int infoDictStartIndex = -1;
 
-    public TorrentFileParser(byte[] bytes) {
+    public TorrentFileParser(byte[] bytes, boolean computeInfoHash) {
         this.bytes = bytes;
+        this.computeInfoHash = computeInfoHash;
     }
 
     private Object parse() throws MalformedTorrentFileException {
@@ -69,15 +71,15 @@ private Map<String, Object> parseDict() throws MalformedTorrentFileException {
                 }
             } else {
                 map.put(key, parseValue);
+                if (key.equals("info") && computeInfoHash && torrentBuilder != null) {
+                    torrentBuilder.setInfoHash(Arrays.copyOfRange(bytes, infoDictStartIndex, iterator));
+                }
                 if (torrentBuilder != null) {
                     torrentBuilder.processKeyValue(key, parseValue);
                 }
                 key = null;
             }
         }
-        if (infoDictStartIndex != -1 && torrentBuilder != null) {
-            torrentBuilder.setInfoHash(Arrays.copyOfRange(bytes, infoDictStartIndex, iterator));
-        }
         iterator++; // Skipping closing e
         return map;
     }

src/main/java/com/robothaver/torrentfileparser/domain/InfoHasCompute.java

@@ -0,0 +1,25 @@
+package com.robothaver.torrentfileparser.domain;
+
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.HexFormat;
+
+public class InfoHasCompute {
+    public static String getInfoHash(byte[] infoBytes) {
+        try {
+            return getSHAsum(infoBytes);
+        } catch (NoSuchAlgorithmException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private static String getSHAsum(byte[] input) throws NoSuchAlgorithmException {
+        MessageDigest messageDigest = MessageDigest.getInstance("SHA-1");
+        return byteArrayToHex(messageDigest.digest(input));
+    }
+
+    private static String byteArrayToHex(byte[] bytes) {
+        HexFormat hex = HexFormat.of();
+        return hex.formatHex(bytes);
+    }
+}

src/main/java/com/robothaver/torrentfileparser/domain/TorrentBuilder.java

@@ -1,8 +1,5 @@
 package com.robothaver.torrentfileparser.domain;
 
-import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
-import java.util.HexFormat;
 import java.util.List;
 import java.util.Map;
 
@@ -34,21 +31,7 @@ public void processKeyValue(String key, Object value) {
     }
 
     public void setInfoHash(byte[] infoBytes) {
-        try {
-            torrent.setInfoHash(getSHAsum(infoBytes));
-        } catch (NoSuchAlgorithmException e) {
-            throw new RuntimeException(e);
-        }
-    }
-
-    private String getSHAsum(byte[] input) throws NoSuchAlgorithmException {
-        MessageDigest messageDigest = MessageDigest.getInstance("SHA-1");
-        return byteArrayToHex(messageDigest.digest(input));
-    }
-
-    private String byteArrayToHex(byte[] bytes) {
-        HexFormat hex = HexFormat.of();
-        return hex.formatHex(bytes);
+        torrent.setInfoHash(InfoHasCompute.getInfoHash(infoBytes));
     }
 
     private String formatFilePath(String path) {