Add base class for security filters rendering errors as json

2 files changed, 94 insertions, 0 deletions

diff --git a/jdisc-security-filters/src/main/java/com/yahoo/jdisc/http/filter/security/base/JsonSecurityRequestFilterBase.java b/jdisc-security-filters/src/main/java/com/yahoo/jdisc/http/filter/security/base/JsonSecurityRequestFilterBase.java
new file mode 100644
index 00000000000..e2440bc4c5f
--- /dev/null
+++ b/jdisc-security-filters/src/main/java/com/yahoo/jdisc/http/filter/security/base/JsonSecurityRequestFilterBase.java
@@ -0,0 +1,86 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.jdisc.http.filter.security.base;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.yahoo.jdisc.Response;
+import com.yahoo.jdisc.handler.FastContentWriter;
+import com.yahoo.jdisc.handler.ResponseDispatch;
+import com.yahoo.jdisc.handler.ResponseHandler;
+import com.yahoo.jdisc.http.filter.DiscFilterRequest;
+import com.yahoo.jdisc.http.filter.SecurityRequestFilter;
+
+import java.io.UncheckedIOException;
+import java.util.Optional;
+
+/**
+ * A base class for {@link SecurityRequestFilter} implementations that renders an error response as JSON.
+ *
+ * @author bjorncs
+ */
+public abstract class JsonSecurityRequestFilterBase implements SecurityRequestFilter {
+
+    private static final ObjectMapper mapper = new ObjectMapper();
+
+    @Override
+    public final void filter(DiscFilterRequest request, ResponseHandler handler) {
+        filter(request)
+                .ifPresent(errorResponse -> writeResponse(errorResponse, handler));
+    }
+
+    protected abstract Optional<ErrorResponse> filter(DiscFilterRequest request);
+
+    private void writeResponse(ErrorResponse error, ResponseHandler responseHandler) {
+        ObjectNode errorMessage = mapper.createObjectNode();
+        errorMessage.put("code", error.errorCode);
+        errorMessage.put("message", error.message);
+        error.response.headers().put("Content-Type", "application/json"); // Note: Overwrites header if already exists
+        try (FastContentWriter writer = ResponseDispatch.newInstance(error.response).connectFastWriter(responseHandler)) {
+            writer.write(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(errorMessage));
+        } catch (JsonProcessingException e) {
+            throw new UncheckedIOException(e);
+        }
+    }
+
+    /**
+     * An error response that contains a {@link Response}, error code and message.
+     * The error code and message will be rendered as JSON fields with name 'code' and 'message' respectively.
+     */
+    protected static class ErrorResponse {
+        private final Response response;
+        private final int errorCode;
+        private final String message;
+
+        public ErrorResponse(Response response, int errorCode, String message) {
+            this.response = response;
+            this.errorCode = errorCode;
+            this.message = message;
+        }
+
+        public ErrorResponse(Response response, String message) {
+            this(response, response.getStatus(), message);
+        }
+
+        public ErrorResponse(int httpStatusCode, int errorCode, String message) {
+            this(new Response(httpStatusCode), errorCode, message);
+        }
+
+        public ErrorResponse(int httpStatusCode, String message) {
+            this(new Response(httpStatusCode), message);
+        }
+
+        public Response getResponse() {
+            return response;
+        }
+
+        public int getErrorCode() {
+            return errorCode;
+        }
+
+        public String getMessage() {
+            return message;
+        }
+
+    }
+}
diff --git a/jdisc-security-filters/src/main/java/com/yahoo/jdisc/http/filter/security/base/package-info.java b/jdisc-security-filters/src/main/java/com/yahoo/jdisc/http/filter/security/base/package-info.java
new file mode 100644
index 00000000000..38f7b126443
--- /dev/null
+++ b/jdisc-security-filters/src/main/java/com/yahoo/jdisc/http/filter/security/base/package-info.java
@@ -0,0 +1,8 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+/**
+ * @author bjorncs
+ */
+@ExportPackage
+package com.yahoo.jdisc.http.filter.security.base;
+
+import com.yahoo.osgi.annotation.ExportPackage;
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