Make HTTP Header class handle multiple cache-control fields.

The HTTP specification states the following about the fields:
Multiple message-header fields with the same field-name MAY be present
in a message if and only if the entire field-value for that header field
is defined as a comma-separated list [i.e., #(values)]. It MUST be
possible to combine the multiple header fields into one "field-name:
field-value" pair, without changing the semantics of the message, by
appending each subsequent field-value to the first, each separated by a
comma. The order in which header fields with the same field-name are
received is therefore significant to the interpretation of the combined
field value, and thus a proxy MUST NOT change the order of these field
values when a message is forwarded.

Change-Id: I1a6fe5cc8f541f8e80d559641d270d09eac9d85c

Author: Henrik Baard

core/java/android/net/http/Headers.java

@@ -262,7 +262,14 @@ public void parseHeader(CharArrayBuffer buffer) {
             break;
         case HASH_CACHE_CONTROL:
             if (name.equals(CACHE_CONTROL)) {
-                mHeaders[IDX_CACHE_CONTROL] = val;
+                // In case where we receive more than one header, create a ',' separated list.
+                // This should be ok, according to RFC 2616 chapter 4.2
+                if (mHeaders[IDX_CACHE_CONTROL] != null &&
+                    mHeaders[IDX_CACHE_CONTROL].length() > 0) {
+                    mHeaders[IDX_CACHE_CONTROL] += (',' + val);
+                } else {
+                    mHeaders[IDX_CACHE_CONTROL] = val;
+                }
             }
             break;
         case HASH_LAST_MODIFIED:

tests/CoreTests/android/core/HttpHeaderTest.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package android.core;
+
+import android.test.AndroidTestCase;
+import org.apache.http.util.CharArrayBuffer;
+
+import android.net.http.Headers;
+
+public class HttpHeaderTest extends AndroidTestCase {
+
+    static final String LAST_MODIFIED = "Last-Modified: Fri, 18 Jun 2010 09:56:47 GMT";
+    static final String CACHE_CONTROL_MAX_AGE = "Cache-Control:max-age=15";
+    static final String CACHE_CONTROL_PRIVATE = "Cache-Control: private";
+
+    /**
+     * Tests that cache control header supports multiple instances of the header,
+     * according to HTTP specification.
+     *
+     * The HTTP specification states the following about the fields:
+     * Multiple message-header fields with the same field-name MAY be present
+     * in a message if and only if the entire field-value for that header field
+     * is defined as a comma-separated list [i.e., #(values)]. It MUST be
+     * possible to combine the multiple header fields into one "field-name:
+     * field-value" pair, without changing the semantics of the message, by
+     * appending each subsequent field-value to the first, each separated by a
+     * comma. The order in which header fields with the same field-name are
+     * received is therefore significant to the interpretation of the combined
+     * field value, and thus a proxy MUST NOT change the order of these field
+     * values when a message is forwarded.
+     */
+    public void testCacheControl() throws Exception {
+        Headers h = new Headers();
+        CharArrayBuffer buffer = new CharArrayBuffer(64);
+
+        buffer.append(CACHE_CONTROL_MAX_AGE);
+        h.parseHeader(buffer);
+
+        buffer.clear();
+        buffer.append(LAST_MODIFIED);
+        h.parseHeader(buffer);
+        assertEquals("max-age=15", h.getCacheControl());
+
+        buffer.clear();
+        buffer.append(CACHE_CONTROL_PRIVATE);
+        h.parseHeader(buffer);
+        assertEquals("max-age=15,private", h.getCacheControl());
+    }
+}