Further generify Adblock host loading

app/src/main/java/acr/browser/lightning/utils/AdBlock.java

@@ -21,6 +21,7 @@ public class AdBlock {
     private static final String TAG = "AdBlock";
     private static final String BLOCKED_DOMAINS_LIST_FILE_NAME = "hosts.txt";
     private static final String LOCAL_IP_V4 = "127.0.0.1";
+    private static final String LOCAL_IP_V4_ALT = "0.0.0.0";
     private static final String LOCAL_IP_V6 = "::1";
     private static final String LOCALHOST = "localhost";
     private static final String COMMENT = "#";
@@ -72,6 +73,12 @@ public class AdBlock {
         thread.start();
     }
 
+    /**
+     * a method that determines if the given URL is an ad or not. It performs
+     * a search of the URL's domain on the blocked domain hash set.
+     * @param url the URL to check for being an ad
+     * @return true if it is an ad, false if it is not an ad
+     */
     public boolean isAd(String url) {
         if (!mBlockAds || url == null) {
             return false;
@@ -92,6 +99,12 @@ public class AdBlock {
         return isOnBlacklist;
     }
 
+    /**
+     * Returns the probable domain name for a given URL
+     * @param url the url to parse
+     * @return returns the domain
+     * @throws URISyntaxException throws an exception if the string cannot form a URI
+     */
     private static String getDomainName(String url) throws URISyntaxException {
         int index = url.indexOf('/', 8);
         if (index != -1) {
@@ -107,6 +120,14 @@ public class AdBlock {
         return domain.startsWith("www.") ? domain.substring(4) : domain;
     }
 
+    /**
+     * This method reads through a hosts file and extracts the domains that should
+     * be redirected to localhost (a.k.a. IP address 127.0.0.1). It can handle files that
+     * simply have a list of hostnames to block, or it can handle a full blown hosts file.
+     * It will strip out comments, references to the base IP address and just extract the
+     * domains to be used
+     * @param context the context needed to read the file
+     */
     private void loadHostsFile(final Context context) {
         Thread thread = new Thread(new Runnable() {
 
@@ -120,7 +141,10 @@ public class AdBlock {
                     String line;
                     while ((line = reader.readLine()) != null) {
                         if (!line.isEmpty() && !line.startsWith(COMMENT)) {
-                            line = line.replace(LOCAL_IP_V4, EMPTY).replace(LOCAL_IP_V6, EMPTY).replace(TAB, EMPTY);
+                            line = line.replace(LOCAL_IP_V4, EMPTY)
+                                    .replace(LOCAL_IP_V4_ALT, EMPTY)
+                                    .replace(LOCAL_IP_V6, EMPTY)
+                                    .replace(TAB, EMPTY);
                             int comment = line.indexOf(COMMENT);
                             if (comment >= 0) {
                                 line = line.substring(0, comment);
@@ -128,9 +152,10 @@ public class AdBlock {
                             line = line.trim();
                             if (!line.isEmpty() && !line.equals(LOCALHOST)) {
                                 while (line.contains(SPACE)) {
-                                    String host = line.substring(0, line.indexOf(SPACE));
+                                    int space = line.indexOf(SPACE);
+                                    String host = line.substring(0, space);
                                     mBlockedDomainsList.add(host.trim());
-                                    line = line.substring(line.indexOf(SPACE), line.length()).trim();
+                                    line = line.substring(space, line.length()).trim();
                                 }
                                 mBlockedDomainsList.add(line.trim());
                             }