Implement containsLast in HttpFields (#10340)

Fully implement list iterator so that we can efficiently check for the last item in a multi header list.

---------

Signed-off-by: gregw <gregw@webtide.com>

jetty-core/jetty-client/src/main/java/org/eclipse/jetty/client/GZIPContentDecoder.java

@@ -51,19 +51,20 @@ public void beforeDecoding(Response response)
         HttpResponse httpResponse = (HttpResponse)response;
         httpResponse.headers(headers ->
         {
-            ListIterator<HttpField> iterator = headers.listIterator();
-            while (iterator.hasNext())
+            boolean seenContentEncoding = false;
+            for (ListIterator<HttpField> iterator = headers.listIterator(headers.size()); iterator.hasPrevious();)
             {
-                HttpField field = iterator.next();
+                HttpField field = iterator.previous();
                 HttpHeader header = field.getHeader();
                 if (header == HttpHeader.CONTENT_LENGTH)
                 {
                     // Content-Length is not valid anymore while we are decoding.
                     iterator.remove();
                 }
-                else if (header == HttpHeader.CONTENT_ENCODING)
+                else if (header == HttpHeader.CONTENT_ENCODING && !seenContentEncoding)
                 {
-                    // Content-Encoding should be removed/modified as the content will be decoded.
+                    // Last Content-Encoding should be removed/modified as the content will be decoded.
+                    seenContentEncoding = true;
                     String value = field.getValue();
                     int comma = value.lastIndexOf(",");
                     if (comma < 0)

jetty-core/jetty-client/src/main/java/org/eclipse/jetty/client/transport/HttpReceiver.java

@@ -258,15 +258,13 @@ protected void responseHeaders(HttpExchange exchange)
             {
                 // Content-Encoding may have multiple values in the order they
                 // are applied, but we only support one decoding pass, the last one.
-                String contentEncoding = responseHeaders.get(HttpHeader.CONTENT_ENCODING);
+                String contentEncoding = responseHeaders.getLast(HttpHeader.CONTENT_ENCODING);
                 if (contentEncoding != null)
                 {
                     int comma = contentEncoding.indexOf(",");
                     if (comma > 0)
                     {
-                        QuotedCSV parser = new QuotedCSV(false);
-                        parser.addValue(contentEncoding);
-                        List<String> values = parser.getValues();
+                        List<String> values = new QuotedCSV(false, contentEncoding).getValues();
                         contentEncoding = values.get(values.size() - 1);
                     }
                 }

jetty-core/jetty-http/src/main/java/org/eclipse/jetty/http/HttpField.java

@@ -362,6 +362,56 @@ else if (c != '0' && c != '.')
         return param != ZERO_QUALITY.length() && match == search.length();
     }
 
+    /**
+     * Look for a value as the last value in a possible multivalued field
+     * Parameters and specifically quality parameters are not considered.
+     * @param search Values to search for (case-insensitive)
+     * @return True iff the value is contained in the field value entirely or
+     * as the last element of a quoted comma separated list.
+     */
+    public boolean containsLast(String search)
+    {
+        return containsLast(getValue(), search);
+    }
+
+    /**
+     * Look for the last value in a possible multivalued field
+     * Parameters and specifically quality parameters are not considered.
+     * @param value The field value to search in.
+     * @param search Values to search for (case-insensitive)
+     * @return True iff the value is contained in the field value entirely or
+     * as the last element of a quoted comma separated list.
+     */
+    public static boolean containsLast(String value, String search)
+    {
+        if (search == null)
+            return value == null;
+        if (search.isEmpty())
+            return false;
+        if (value == null)
+            return false;
+        if (search.equalsIgnoreCase(value))
+            return true;
+
+        if (value.endsWith(search))
+        {
+            int i = value.length() - search.length() - 1;
+            while (i >= 0)
+            {
+                char c = value.charAt(i--);
+                if (c == ',')
+                    return true;
+                if (c != ' ')
+                    return false;
+            }
+            return true;
+        }
+
+        QuotedCSV csv = new QuotedCSV(false, value);
+        List<String> values = csv.getValues();
+        return !values.isEmpty() && search.equalsIgnoreCase(values.get(values.size() - 1));
+    }
+
     @Override
     public int hashCode()
     {

jetty-core/jetty-http/src/main/java/org/eclipse/jetty/http/HttpFields.java

@@ -161,6 +161,27 @@ default HttpFields get()
         return this;
     }
 
+    @Override
+    default Iterator<HttpField> iterator()
+    {
+        return listIterator();
+    }
+
+    /**
+     * @return an iterator over the {@link HttpField}s in this {@code HttpFields}.
+     * @see #listIterator(int)
+     */
+    default ListIterator<HttpField> listIterator()
+    {
+        return listIterator(0);
+    }
+
+    /**
+     * @return an iterator over the {@link HttpField}s in this {@code HttpFields} starting at the given index.
+     * @see #listIterator()
+     */
+    ListIterator<HttpField> listIterator(int index);
+
     /**
      * <p>Returns an immutable copy of this {@link HttpFields} instance.</p>
      *
@@ -245,6 +266,27 @@ default boolean contains(HttpHeader header, String value)
         return false;
     }
 
+    /**
+     * Look for a value as the last value in a possible multivalued field.
+     * Parameters and specifically quality parameters are not considered.
+     * @param header The {@link HttpHeader} type to search for.
+     * @param value The value to search for (case-insensitive)
+     * @return True iff the value is contained in the field value entirely or
+     * as the last element of a quoted comma separated list.
+     * @see HttpField#containsLast(String)
+     */
+    default boolean containsLast(HttpHeader header, String value)
+    {
+        for (ListIterator<HttpField> i = listIterator(size()); i.hasPrevious();)
+        {
+            HttpField f = i.previous();
+
+            if (f.getHeader() == header)
+                return f.containsLast(value);
+        }
+        return false;
+    }
+
     /**
      * <p>Returns whether this instance contains the given field name
      * with the given value.</p>
@@ -340,6 +382,28 @@ default String get(HttpHeader header)
         return null;
     }
 
+    /**
+     * <p>Returns the encoded value of the last field with the given field name,
+     * or {@code null} if no such header is present.</p>
+     * <p>In case of multi-valued fields, the returned value is the encoded
+     * value, including commas and quotes, as returned by {@link HttpField#getValue()}.</p>
+     *
+     * @param header the field name to search for
+     * @return the raw value of the last field with the given field name,
+     * or {@code null} if no such header is present
+     * @see HttpField#getValue()
+     */
+    default String getLast(HttpHeader header)
+    {
+        for (ListIterator<HttpField> i = listIterator(size()); i.hasPrevious();)
+        {
+            HttpField f = i.previous();
+            if (f.getHeader() == header)
+                return f.getValue();
+        }
+        return null;
+    }
+
     /**
      * <p>Returns the encoded value of the first field with the given field name,
      * or {@code null} if no such field is present.</p>
@@ -904,11 +968,7 @@ default Mutable add(HttpHeader header, long value)
          */
         default Mutable add(HttpField field)
         {
-            ListIterator<HttpField> i = listIterator();
-            while (i.hasNext())
-            {
-                i.next();
-            }
+            ListIterator<HttpField> i = listIterator(size());
             i.add(field);
             return this;
         }
@@ -1041,20 +1101,6 @@ default void ensureField(HttpField field)
             }
         }
 
-        /**
-         * @return an {@link Iterator} over the {@link HttpField}s of this instance
-         */
-        @Override
-        default Iterator<HttpField> iterator()
-        {
-            return listIterator();
-        }
-
-        /**
-         * @return a {@link ListIterator} over the {@link HttpField}s of this instance
-         */
-        ListIterator<HttpField> listIterator();
-
         /**
          * <p>Puts the given {@link HttpField} into this instance.</p>
          * <p>If a fields with the same name is present, the given field
@@ -1111,7 +1157,7 @@ default Mutable put(String name, String value)
          * <p>This method behaves like {@link #remove(HttpHeader)} when
          * the given {@code value} is {@code null}, otherwise behaves
          * like {@link #put(HttpField)}.</p>
-         * 
+         *
          * @param header the name of the field
          * @param value the value of the field; if {@code null} the field is removed
          * @return this instance
@@ -1590,9 +1636,9 @@ public Mutable clear()
             }
 
             @Override
-            public ListIterator<HttpField> listIterator()
+            public ListIterator<HttpField> listIterator(int index)
             {
-                ListIterator<HttpField> i = _fields.listIterator();
+                ListIterator<HttpField> i = _fields.listIterator(index);
                 return new ListIterator<>()
                 {
                     HttpField last;

jetty-core/jetty-http/src/main/java/org/eclipse/jetty/http/ImmutableHttpFields.java

@@ -14,7 +14,7 @@
 package org.eclipse.jetty.http;
 
 import java.util.Arrays;
-import java.util.Iterator;
+import java.util.ListIterator;
 import java.util.NoSuchElementException;
 import java.util.Objects;
 import java.util.stream.Stream;
@@ -134,24 +134,9 @@ public HttpField getField(int index)
     }
 
     @Override
-    public Iterator<HttpField> iterator()
+    public ListIterator<HttpField> listIterator(int index)
     {
-        return new Iterator<>()
-        {
-            int _index = 0;
-
-            @Override
-            public boolean hasNext()
-            {
-                return _index < _size;
-            }
-
-            @Override
-            public HttpField next()
-            {
-                return _fields[_index++];
-            }
-        };
+        return new Listerator(index);
     }
 
     @Override
@@ -171,4 +156,77 @@ public String toString()
     {
         return asString();
     }
+
+    private class Listerator implements ListIterator<HttpField>
+    {
+        private int _index;
+        private int _last = -1;
+
+        Listerator(int index)
+        {
+            if (index < 0 || index > _size)
+                throw new NoSuchElementException(Integer.toString(index));
+            _index = index;
+        }
+
+        @Override
+        public void add(HttpField field)
+        {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public boolean hasNext()
+        {
+            return _index < _size;
+        }
+
+        @Override
+        public boolean hasPrevious()
+        {
+            return _index > 0;
+        }
+
+        @Override
+        public HttpField next()
+        {
+            if (_index >= _size)
+                throw new NoSuchElementException(Integer.toString(_index));
+            _last = _index++;
+            return _fields[_last];
+        }
+
+        @Override
+        public int nextIndex()
+        {
+            return _index + 1;
+        }
+
+        @Override
+        public HttpField previous()
+        {
+            if (_index <= 0)
+                throw new NoSuchElementException(Integer.toString(_index - 1));
+            _last = --_index;
+            return _fields[_last];
+        }
+
+        @Override
+        public int previousIndex()
+        {
+            return _index - 1;
+        }
+
+        @Override
+        public void remove()
+        {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public void set(HttpField field)
+        {
+            throw new UnsupportedOperationException();
+        }
+    }
 }