Generalize S3HttpHandler request matching (elastic#125670)

The pattern-matching in `S3HttpHandler` is overly specific and carefully
crafted to handle the exact requests that the AWS SDK v1 makes. It turns
out that the AWS SDK v2 makes requests that are slightly different. This
commit generalizes the pattern-matching to handle both SDKs.

Author: DaveCTurner

test/fixtures/s3-fixture/src/main/java/fixture/s3/S3HttpHandler.java

@@ -150,7 +150,7 @@ public void handle(final HttpExchange exchange) throws IOException {
                 exchange.sendResponseHeaders(RestStatus.OK.getStatus(), response.length);
                 exchange.getResponseBody().write(response);
 
-            } else if (Regex.simpleMatch("PUT /" + path + "/*?uploadId=*&partNumber=*", request)) {
+            } else if (isUploadPartRequest(request)) {
                 final Map<String, String> params = new HashMap<>();
                 RestUtils.decodeQueryString(request, request.indexOf('?') + 1, params);
 
@@ -213,7 +213,7 @@ public void handle(final HttpExchange exchange) throws IOException {
                 exchange.getResponseHeaders().add("ETag", blob.v1());
                 exchange.sendResponseHeaders(RestStatus.OK.getStatus(), -1);
 
-            } else if (Regex.simpleMatch("GET /" + bucket + "/?prefix=*", request)) {
+            } else if (isListObjectsRequest(request)) {
                 final Map<String, String> params = new HashMap<>();
                 RestUtils.decodeQueryString(request, request.indexOf('?') + 1, params);
                 if (params.get("list-type") != null) {
@@ -315,7 +315,7 @@ public void handle(final HttpExchange exchange) throws IOException {
                 }
                 exchange.sendResponseHeaders((deletions > 0 ? RestStatus.OK : RestStatus.NO_CONTENT).getStatus(), -1);
 
-            } else if (Regex.simpleMatch("POST /" + bucket + "/?delete", request)) {
+            } else if (isMultiObjectDeleteRequest(request)) {
                 final String requestBody = Streams.copyToString(new InputStreamReader(exchange.getRequestBody(), UTF_8));
 
                 final StringBuilder deletes = new StringBuilder();
@@ -337,16 +337,36 @@ public void handle(final HttpExchange exchange) throws IOException {
                 exchange.getResponseBody().write(response);
 
             } else {
+                logger.error("unknown request: {}", request);
                 exchange.sendResponseHeaders(RestStatus.INTERNAL_SERVER_ERROR.getStatus(), -1);
             }
+        } catch (Exception e) {
+            logger.error("exception in request " + request, e);
+            throw e;
         } finally {
             exchange.close();
         }
     }
 
+    private boolean isUploadPartRequest(String request) {
+        return Regex.simpleMatch("PUT /" + path + "/*?uploadId=*&partNumber=*", request)
+            || Regex.simpleMatch("PUT /" + path + "/*?partNumber=*&uploadId=*", request);
+    }
+
     private boolean isListMultipartUploadsRequest(String request) {
         return Regex.simpleMatch("GET /" + bucket + "/?uploads&prefix=*", request)
-            || Regex.simpleMatch("GET /" + bucket + "/?uploads&max-uploads=*&prefix=*", request);
+            || Regex.simpleMatch("GET /" + bucket + "/?uploads&max-uploads=*&prefix=*", request)
+            || Regex.simpleMatch("GET /" + bucket + "?uploads&prefix=*", request)
+            || Regex.simpleMatch("GET /" + bucket + "?uploads&max-uploads=*&prefix=*", request);
+    }
+
+    private boolean isListObjectsRequest(String request) {
+        return Regex.simpleMatch("GET /" + bucket + "/?prefix=*", request)
+            || Regex.simpleMatch("GET /" + bucket + "?list-type=2&*prefix=*", request);
+    }
+
+    private boolean isMultiObjectDeleteRequest(String request) {
+        return request.equals("POST /" + bucket + "/?delete") || request.equals("POST /" + bucket + "?delete");
     }
 
     public Map<String, BytesReference> blobs() {