Accept ';' '\\"' in the filename of HTTP Content-Disposition header

Motivation:
HttpPostMultipartRequestDecoder threw an ArrayIndexOutOfBoundsException
when trying to decode Content-Disposition header with filename
containing ';' or protected \\".
See issue #3326 and #3327.

Modifications:
Added splitMultipartHeaderValues method which cares about quotes, and
use it in splitMultipartHeader method, instead of StringUtils.split.

Result:
Filenames can contain semicolons and protected \\".

codec-http/src/main/java/io/netty/handler/codec/http/multipart/HttpPostMultipartRequestDecoder.java

@@ -1786,7 +1786,7 @@ public class HttpPostMultipartRequestDecoder implements InterfaceHttpPostRequest
         String svalue = sb.substring(valueStart, valueEnd);
         String[] values;
         if (svalue.indexOf(';') >= 0) {
-            values = StringUtil.split(svalue, ';');
+            values = splitMultipartHeaderValues(svalue);
         } else {
             values = StringUtil.split(svalue, ',');
         }
@@ -1799,4 +1799,38 @@ public class HttpPostMultipartRequestDecoder implements InterfaceHttpPostRequest
         }
         return array;
     }
+
+    /**
+     * Split one header value in Multipart
+     * @return an array of String where values that were separated by ';' or ','
+     */
+    private static String[] splitMultipartHeaderValues(String svalue) {
+        List<String> values = new ArrayList<String>(1);
+        boolean inQuote = false;
+        boolean escapeNext = false;
+        int start = 0;
+        for (int i = 0; i < svalue.length(); i++) {
+            char c = svalue.charAt(i);
+            if (inQuote) {
+                if (escapeNext) {
+                    escapeNext = false;
+                } else {
+                    if (c == '\\') {
+                        escapeNext = true;
+                    } else if (c == '"') {
+                        inQuote = false;
+                    }
+                }
+            } else {
+                if (c == '"') {
+                    inQuote = true;
+                } else if (c == ';') {
+                    values.add(svalue.substring(start, i));
+                    start = i + 1;
+                }
+            }
+        }
+        values.add(svalue.substring(start));
+        return values.toArray(new String[values.size()]);
+    }
 }

codec-http/src/test/java/io/netty/handler/codec/http/multipart/HttpPostRequestDecoderTest.java

@@ -321,4 +321,30 @@ public class HttpPostRequestDecoderTest {
         decoder.offer(part3);
         decoder.offer(part4);
     }
+
+    // See https://github.com/netty/netty/issues/3326
+    @Test
+    public void testFilenameContainingSemicolon() throws Exception {
+        final String boundary = "dLV9Wyq26L_-JQxk6ferf-RT153LhOO";
+        final DefaultFullHttpRequest req = new DefaultFullHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.POST,
+                "http://localhost");
+        req.headers().add(HttpHeaders.Names.CONTENT_TYPE, "multipart/form-data; boundary=" + boundary);
+        // Force to use memory-based data.
+        final DefaultHttpDataFactory inMemoryFactory = new DefaultHttpDataFactory(false);
+        final String data = "asdf";
+        final String filename = "tmp;0.txt";
+        final String body =
+                "--" + boundary + "\r\n" +
+                        "Content-Disposition: form-data; name=\"file\"; filename=\"" + filename + "\"\r\n" +
+                        "Content-Type: image/gif\r\n" +
+                        "\r\n" +
+                        data + "\r\n" +
+                        "--" + boundary + "--\r\n";
+
+        req.content().writeBytes(body.getBytes(CharsetUtil.UTF_8.name()));
+        // Create decoder instance to test.
+        final HttpPostRequestDecoder decoder = new HttpPostRequestDecoder(inMemoryFactory, req);
+        assertFalse(decoder.getBodyHttpDatas().isEmpty());
+        decoder.destroy();
+    }
 }