Merge remote-tracking branch 'lachlan/jetty-9.4.x-1027-SearchPattern' into jetty-9.4.x-1027-Multipart

jetty-util/src/main/java/org/eclipse/jetty/util/SearchPattern.java

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+//
+//  ========================================================================
+//  Copyright (c) 1995-2018 Mort Bay Consulting Pty. Ltd.
+//  ------------------------------------------------------------------------
+//  All rights reserved. This program and the accompanying materials
+//  are made available under the terms of the Eclipse Public License v1.0
+//  and Apache License v2.0 which accompanies this distribution.
+//
+//      The Eclipse Public License is available at
+//      http://www.eclipse.org/legal/epl-v10.html
+//
+//      The Apache License v2.0 is available at
+//      http://www.opensource.org/licenses/apache2.0.php
+//
+//  You may elect to redistribute this code under either of these licenses.
+//  ========================================================================
+//
+
+package org.eclipse.jetty.util;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+
+
+/**
+ * SearchPattern
+ *
+ * Fast search for patterns within strings and arrays of bytes.
+ * Uses an implementation of the Boyer–Moore–Horspool algorithm
+ * with a 256 character alphabet.
+ * 
+ * The algorithm has an average-case complexity of O(n) 
+ * on random text and O(nm) in the worst case.
+ * where: 
+ *    m = pattern length
+ *    n = length of data to search
+ */
+public class SearchPattern
+{
+    static final int alphabetSize = 256;
+    private int[] table;
+    private byte[] pattern;    
+    
+    /**
+     * Produces a SearchPattern instance which can be used
+     * to find matches of the pattern in data
+     * @param pattern byte array containing the pattern
+     * @return a new SearchPattern instance using the given pattern
+     */
+    public static SearchPattern compile(byte[] pattern)
+    {
+        return new SearchPattern(Arrays.copyOf(pattern, pattern.length));
+    }
+    
+    /**
+     * Produces a SearchPattern instance which can be used
+     * to find matches of the pattern in data
+     * @param pattern string containing the pattern
+     * @return a new SearchPattern instance using the given pattern
+     */
+    public static SearchPattern compile(String pattern)
+    {
+        return new SearchPattern(pattern.getBytes(StandardCharsets.UTF_8));
+    }
+    
+    /**
+     * @param pattern byte array containing the pattern used for matching
+     */
+    private SearchPattern(byte[] pattern)
+    {
+        this.pattern = pattern;
+        
+        if(pattern.length == 0) 
+            throw new IllegalArgumentException("Empty Pattern");
+        
+        //Build up the pre-processed table for this pattern.
+        table = new int[alphabetSize];
+        for(int i = 0; i<table.length; ++i)
+            table[i] = pattern.length;
+        for(int i = 0; i<pattern.length-1; ++i)
+            table[pattern[i]] = pattern.length-1-i;
+    }
+    
+    
+    /**
+     * Search for a complete match of the pattern within the data
+     * @param data The data in which to search for. The data may be arbitrary binary data, 
+     * but the pattern will always be {@link StandardCharsets#US_ASCII} encoded.
+     * @param offset The offset within the data to start the search
+     * @param length The length of the data to search
+     * @return The index within the data array at which the first instance of the pattern or -1 if not found
+     */
+    public int match(byte[] data, int offset, int length)
+    {
+        validate(data, offset, length);
+
+        int skip = offset;
+        while(skip <= offset+length - pattern.length)
+        {            
+            for(int i = pattern.length-1; data[skip+i] == pattern[i]; i--) 
+                if(i==0) return skip;
+            
+            skip += table[data[skip + pattern.length - 1]];
+        }
+        
+        return -1;
+    }
+    
+    /**
+     * Search for a partial match of the pattern at the end of the data.
+     * @param data The data in which to search for. The data may be arbitrary binary data, 
+     * but the pattern will always be {@link StandardCharsets#US_ASCII} encoded.
+     * @param offset The offset within the data to start the search
+     * @param length The length of the data to search
+     * @return the length of the partial pattern matched and 0 for no match.
+     */
+    public int endsWith(byte[] data, int offset, int length)
+    { 
+        validate(data, offset, length);
+        
+        int skip = (pattern.length <= length) ? (offset+length-pattern.length) : offset;
+        while(skip < offset+length)
+        {       
+            for(int i = (offset+length-1)-skip; data[skip+i] == pattern[i]; --i)
+                if(i==0) return(offset+length - skip);
+            
+            if(skip + pattern.length - 1 < data.length)
+                skip += table[data[skip + pattern.length - 1]];
+            else
+                skip++;
+        }
+        
+        return 0;
+    }
+    
+    /**
+     * Search for a possibly partial match of the pattern at the start of the data.
+     * @param data The data in which to search for. The data may be arbitrary binary data, 
+     * but the pattern will always be {@link StandardCharsets#US_ASCII} encoded.
+     * @param offset The offset within the data to start the search
+     * @param length The length of the data to search
+     * @param matched The length of the partial pattern already matched
+     * @return the length of the partial pattern matched and 0 for no match.
+     */
+    public int startsWith(byte[] data, int offset, int length, int matched)
+    {
+        validate(data, offset, length);
+        
+        int matchedCount = 0;
+        
+        for(int i=0; i<pattern.length-matched && i < offset+length; i++)
+        {
+            if(data[i] == pattern[i+matched])
+                matchedCount++;
+            else
+                break;
+        }
+        
+        return matchedCount;   
+    }
+    
+    /**
+     * Performs legality checks for standard arguments input into SearchPattern methods.
+     * @param data The data in which to search for. The data may be arbitrary binary data, 
+     * but the pattern will always be {@link StandardCharsets#US_ASCII} encoded.
+     * @param offset The offset within the data to start the search
+     * @param length The length of the data to search
+     */
+    private void validate(byte[] data, int offset, int length)
+    {
+        if (offset < 0)
+            throw new IllegalArgumentException("offset was negative");
+        else if (length < 0)
+            throw new IllegalArgumentException("length was negative");
+        else if (offset + length > data.length)
+            throw new IllegalArgumentException("(offset+length) out of bounds of data[]");
+    }
+    
+}

jetty-util/src/test/java/org/eclipse/jetty/util/SearchPatternTest.java

@@ -0,0 +1,172 @@
+//
+//  ========================================================================
+//  Copyright (c) 1995-2018 Mort Bay Consulting Pty. Ltd.
+//  ------------------------------------------------------------------------
+//  All rights reserved. This program and the accompanying materials
+//  are made available under the terms of the Eclipse Public License v1.0
+//  and Apache License v2.0 which accompanies this distribution.
+//
+//      The Eclipse Public License is available at
+//      http://www.eclipse.org/legal/epl-v10.html
+//
+//      The Apache License v2.0 is available at
+//      http://www.opensource.org/licenses/apache2.0.php
+//
+//  You may elect to redistribute this code under either of these licenses.
+//  ========================================================================
+//
+
+package org.eclipse.jetty.util;
+
+
+import java.nio.charset.StandardCharsets;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class SearchPatternTest
+
+{
+
+    
+    @Test
+    public void testBasicSearch()
+    {
+        byte[] p1 = new String("truth").getBytes(StandardCharsets.US_ASCII);
+        byte[] p2 = new String("evident").getBytes(StandardCharsets.US_ASCII);
+        byte[] p3 = new String("we").getBytes(StandardCharsets.US_ASCII);
+        byte[] d = new String("we hold these truths to be self evident").getBytes(StandardCharsets.US_ASCII);
+        
+        // Testing Compiled Pattern p1 "truth"
+        SearchPattern sp1 = SearchPattern.compile(p1);
+        Assert.assertEquals(14,sp1.match(d, 0, d.length));        
+        Assert.assertEquals(14,sp1.match(d,14,p1.length));        
+        Assert.assertEquals(14,sp1.match(d,14,p1.length+1));
+        Assert.assertEquals(-1,sp1.match(d,14,p1.length-1));        
+        Assert.assertEquals(-1,sp1.match(d,15,d.length-15));
+        
+        // Testing Compiled Pattern p2 "evident"
+        SearchPattern sp2 = SearchPattern.compile(p2);        
+        Assert.assertEquals(32,sp2.match(d, 0, d.length));        
+        Assert.assertEquals(32,sp2.match(d,32,p2.length));        
+        Assert.assertEquals(32,sp2.match(d,32,p2.length));        
+        Assert.assertEquals(-1,sp2.match(d,32,p2.length-1));        
+        Assert.assertEquals(-1,sp2.match(d,33,d.length-33));
+        
+        // Testing Compiled Pattern p3 "evident"
+        SearchPattern sp3 = SearchPattern.compile(p3);   
+        Assert.assertEquals( 0,sp3.match(d, 0, d.length));
+        Assert.assertEquals( 0,sp3.match(d, 0, p3.length));
+        Assert.assertEquals( 0,sp3.match(d, 0, p3.length+1));
+        Assert.assertEquals(-1,sp3.match(d, 0, p3.length-1));
+        Assert.assertEquals(-1,sp3.match(d, 1, d.length-1));
+        
+    }
+    
+    
+    @Test
+    public void testDoubleMatch()
+    {
+        byte[] p = new String("violent").getBytes(StandardCharsets.US_ASCII);
+        byte[] d = new String("These violent delights have violent ends.").getBytes(StandardCharsets.US_ASCII);
+        SearchPattern sp = SearchPattern.compile(p);
+        Assert.assertEquals( 6,sp.match(d, 0, d.length));
+        Assert.assertEquals(-1,sp.match(d, 6, p.length-1));
+        Assert.assertEquals(28,sp.match(d, 7, d.length-7));
+        Assert.assertEquals(28,sp.match(d, 28, d.length-28));
+        Assert.assertEquals(-1,sp.match(d, 29, d.length-29));
+    }
+
+    
+    @Test
+    public void testAlmostMatch()
+    {
+        byte[] p = new String("violent").getBytes(StandardCharsets.US_ASCII);
+        byte[] d = new String("vio lent violen v iolent violin vioviolenlent viiolent").getBytes(StandardCharsets.US_ASCII);
+        SearchPattern sp = SearchPattern.compile(p);
+        Assert.assertEquals(-1,sp.match(d, 0, d.length));
+    }
+    
+    
+    @Test
+    public void testOddSizedPatterns()
+    {
+        // Test Large Pattern
+        byte[] p = new String("pneumonoultramicroscopicsilicovolcanoconiosis").getBytes(StandardCharsets.US_ASCII);
+        byte[] d = new String("pneumon").getBytes(StandardCharsets.US_ASCII);
+        SearchPattern sp = SearchPattern.compile(p);
+        Assert.assertEquals(-1,sp.match(d, 0, d.length));
+        
+        // Test Single Character Pattern
+        p = new String("s").getBytes(StandardCharsets.US_ASCII);
+        d = new String("the cake is a lie").getBytes(StandardCharsets.US_ASCII);
+        sp = SearchPattern.compile(p);
+        Assert.assertEquals(10,sp.match(d, 0, d.length));
+    }
+    
+    
+    @Test
+    public void testEndsWith()
+    {
+        byte[] p = new String("pneumonoultramicroscopicsilicovolcanoconiosis").getBytes(StandardCharsets.US_ASCII);
+        byte[] d = new String("pneumonoultrami").getBytes(StandardCharsets.US_ASCII);
+        SearchPattern sp = SearchPattern.compile(p);
+        Assert.assertEquals(15,sp.endsWith(d,0,d.length));
+        
+        p = new String("abcdefghijklmnopqrstuvwxyz").getBytes(StandardCharsets.US_ASCII);
+        d = new String("abcdefghijklmnopqrstuvwxyzabcdefghijklmno").getBytes(StandardCharsets.US_ASCII);
+        sp = SearchPattern.compile(p);
+        Assert.assertEquals(0,sp.match(d,0,d.length));
+        Assert.assertEquals(-1,sp.match(d,1,d.length-1));
+        Assert.assertEquals(15,sp.endsWith(d,0,d.length));
+        
+        p = new String("abcdefghijklmnopqrstuvwxyz").getBytes(StandardCharsets.US_ASCII);
+        d = new String("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz").getBytes(StandardCharsets.US_ASCII);
+        sp = SearchPattern.compile(p);
+        Assert.assertEquals(0,sp.match(d,0,d.length));
+        Assert.assertEquals(26,sp.match(d,1,d.length-1));
+        Assert.assertEquals(26,sp.endsWith(d,0,d.length));
+        
+        //test no match
+        p = new String("hello world").getBytes(StandardCharsets.US_ASCII);
+        d = new String("there is definitely no match in here").getBytes(StandardCharsets.US_ASCII);
+        sp = SearchPattern.compile(p);
+        Assert.assertEquals(0,sp.endsWith(d,0,d.length));
+    }
+    
+    
+    @Test
+    public void testStartsWith()
+    {
+        byte[] p = new String("abcdefghijklmnopqrstuvwxyz").getBytes(StandardCharsets.US_ASCII);
+        byte[] d = new String("ijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz").getBytes(StandardCharsets.US_ASCII);
+        SearchPattern sp = SearchPattern.compile(p);
+        Assert.assertEquals(18,sp.match(d,0,d.length));
+        Assert.assertEquals(-1,sp.match(d,19,d.length-19));
+        Assert.assertEquals(18,sp.startsWith(d,0,d.length,8));
+        
+        p = new String("abcdefghijklmnopqrstuvwxyz").getBytes(StandardCharsets.US_ASCII);
+        d = new String("ijklmnopqrstuvwxyz abcdefghijklmnopqrstuvwxyz").getBytes(StandardCharsets.US_ASCII);
+        sp = SearchPattern.compile(p);
+        Assert.assertEquals(19,sp.match(d,0,d.length));
+        Assert.assertEquals(-1,sp.match(d,20,d.length-20));
+        Assert.assertEquals(18,sp.startsWith(d,0,d.length,8));
+        
+        p = new String("abcdefghijklmnopqrstuvwxyz").getBytes(StandardCharsets.US_ASCII);
+        d = new String("abcdefghijklmnopqrstuvwxyz abcdefghijklmnopqrstuvwxyz").getBytes(StandardCharsets.US_ASCII);
+        sp = SearchPattern.compile(p);
+        Assert.assertEquals(26,sp.startsWith(d,0,d.length,0));
+        
+        //test no match
+        p = new String("hello world").getBytes(StandardCharsets.US_ASCII);
+        d = new String("there is definitely no match in here").getBytes(StandardCharsets.US_ASCII);
+        sp = SearchPattern.compile(p);
+        Assert.assertEquals(0,sp.startsWith(d,0,d.length,0));  
+        
+        //test large pattern small buffer
+        p = new String("abcdefghijklmnopqrstuvwxyz").getBytes(StandardCharsets.US_ASCII);
+        d = new String("mnopqrs").getBytes(StandardCharsets.US_ASCII);
+        sp = SearchPattern.compile(p);
+        Assert.assertEquals(7,sp.startsWith(d,0,d.length,12));  
+    }
+}