Consistently compared unquoted ETags

Also use the ETag from listing parts which resolves an issue with
Swift multipart upload due to use of quoted ETags in the client S3
request and unquoted in underlying Swift request.

src/main/java/org/gaul/s3proxy/S3ProxyHandler.java

@@ -973,7 +973,7 @@ final class S3ProxyHandler extends AbstractHandler {
                         eTag = BaseEncoding.base16().lowerCase().encode(
                                 BaseEncoding.base64().decode(eTag));
                     }
-                    writeSimpleElement(xml, "ETag", "\"" + eTag + "\"");
+                    writeSimpleElement(xml, "ETag", maybeQuoteETag(eTag));
                 }
 
                 writeSimpleElement(xml, "Size",
@@ -1185,7 +1185,7 @@ final class S3ProxyHandler extends AbstractHandler {
             writeSimpleElement(xml, "LastModified",
                     blobStore.getContext().utils().date()
                             .iso8601DateFormat(blobMetadata.getLastModified()));
-            writeSimpleElement(xml, "ETag", "\"" + eTag + "\"");
+            writeSimpleElement(xml, "ETag", maybeQuoteETag(eTag));
 
             xml.writeEndElement();
             xml.flush();
@@ -1283,11 +1283,7 @@ final class S3ProxyHandler extends AbstractHandler {
                 }
             }
 
-            // S3 quotes ETag while Swift does not
-            if (!eTag.startsWith("\"") && !eTag.endsWith("\"")) {
-                eTag = '"' + eTag + '"';
-            }
-            response.addHeader(HttpHeaders.ETAG, eTag);
+            response.addHeader(HttpHeaders.ETAG, maybeQuoteETag(eTag));
         }
 
         // TODO: jclouds should include this in PutOptions
@@ -1374,12 +1370,12 @@ final class S3ProxyHandler extends AbstractHandler {
                             partSize != -1 && it.hasNext()) {
                         throw new S3Exception(S3ErrorCode.ENTITY_TOO_SMALL);
                     }
-                    String partETag = "\"" + part.partETag() + "\"";
-                    if (!partETag.equals(entry.getValue())) {
+                    if (!equalsIgnoringSurroundingQuotes(part.partETag(),
+                            entry.getValue())) {
                         throw new S3Exception(S3ErrorCode.INVALID_PART);
                     }
                     parts.add(MultipartPart.create(entry.getKey(),
-                            partSize, entry.getValue()));
+                            partSize, part.partETag()));
                 }
             }
         }
@@ -1410,7 +1406,7 @@ final class S3ProxyHandler extends AbstractHandler {
                     eTag = BaseEncoding.base16().lowerCase().encode(
                             BaseEncoding.base64().decode(eTag));
                 }
-                writeSimpleElement(xml, "ETag", "\"" + eTag + "\"");
+                writeSimpleElement(xml, "ETag", maybeQuoteETag(eTag));
             }
 
             xml.writeEndElement();
@@ -1498,7 +1494,7 @@ final class S3ProxyHandler extends AbstractHandler {
                         eTag = BaseEncoding.base16().lowerCase().encode(
                                 BaseEncoding.base64().decode(eTag));
                     }
-                    writeSimpleElement(xml, "ETag", "\"" + eTag + "\"");
+                    writeSimpleElement(xml, "ETag", maybeQuoteETag(eTag));
                 }
 
                 writeSimpleElement(xml, "Size", String.valueOf(
@@ -1609,9 +1605,9 @@ final class S3ProxyHandler extends AbstractHandler {
                     blobStore.uploadMultipartPart(mpu,
                             10_000 * partNumber + subPartNumber, payload);
                 }
-                response.addHeader(HttpHeaders.ETAG, "\"" +
+                response.addHeader(HttpHeaders.ETAG, maybeQuoteETag(
                         BaseEncoding.base16().lowerCase().encode(
-                                his.hash().asBytes()) + "\"");
+                                his.hash().asBytes())));
             } else {
                 Payload payload = Payloads.newInputStreamPayload(is);
                 payload.getContentMetadata().setContentLength(contentLength);
@@ -1622,7 +1618,7 @@ final class S3ProxyHandler extends AbstractHandler {
                 MultipartPart part = blobStore.uploadMultipartPart(mpu,
                         partNumber, payload);
                 response.addHeader(HttpHeaders.ETAG,
-                        "\"" + part.partETag() + "\"");
+                        maybeQuoteETag(part.partETag()));
             }
         }
     }
@@ -1645,9 +1641,8 @@ final class S3ProxyHandler extends AbstractHandler {
             byte[] contentMd5Bytes = contentMd5.asBytes();
             response.addHeader(HttpHeaders.CONTENT_MD5,
                     BaseEncoding.base64().encode(contentMd5Bytes));
-            response.addHeader(HttpHeaders.ETAG, "\"" +
-                    BaseEncoding.base16().lowerCase().encode(contentMd5Bytes) +
-                    "\"");
+            response.addHeader(HttpHeaders.ETAG, maybeQuoteETag(
+                    BaseEncoding.base16().lowerCase().encode(contentMd5Bytes)));
         }
         Date expires = contentMetadata.getExpires();
         if (expires != null) {
@@ -1939,4 +1934,22 @@ final class S3ProxyHandler extends AbstractHandler {
                 .build()
                 .getMetadata();
     }
+
+    private static boolean equalsIgnoringSurroundingQuotes(String s1,
+            String s2) {
+        if (s1.length() >= 2 && s1.startsWith("\"") && s1.endsWith("\"")) {
+            s1 = s1.substring(1, s1.length() - 1);
+        }
+        if (s2.length() >= 2 && s2.startsWith("\"") && s2.endsWith("\"")) {
+            s2 = s2.substring(1, s2.length() - 1);
+        }
+        return s1.equals(s2);
+    }
+
+    private static String maybeQuoteETag(String eTag) {
+        if (!eTag.startsWith("\"") && !eTag.endsWith("\"")) {
+            eTag = "\"" + eTag + "\"";
+        }
+        return eTag;
+    }
 }