From 749c8966aff781c0a8e5b114df64aeb76e1e9bdb Mon Sep 17 00:00:00 2001
From: Fraser Tweedale <ftweedal@redhat.com>
Date: Thu, 30 May 2019 19:44:00 +1000
Subject: [PATCH] PKIExceptionMapper: coerce media type to XML or JSON

Some resources do not return (upon success) application/json or
application/xml.  For example, some resources in AuthorityService
can return application/pkix-cert, application/x-pem-file or
application/pkcs7-mime.  But if a PKIException exception (e.g.
ResourceNotFoundException) occurs in such a method, RESTEasy can't
turn the PKIException.Data entity into the declared media type, and
it throws a NoMessageBodyWriterFoundFailure, causing a 500 Internal
Server Error response.

Update PKIExceptionMapper to always coerce the response Content-Type
to either application/xml or application/json.  If the Accept header
preferences one of these, the preferred media type is used.
Otherwise we default to application/xml.

Fixes: https://pagure.io/dogtagpki/issue/3102
(cherry picked from commit bef30cde3a452a459c5d29010861314dd8b86642)
---
 .../org/dogtagpki/server/rest/PKIExceptionMapper.java | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/base/server/cms/src/org/dogtagpki/server/rest/PKIExceptionMapper.java b/base/server/cms/src/org/dogtagpki/server/rest/PKIExceptionMapper.java
index 072ac05..0cfab44 100644
--- a/base/server/cms/src/org/dogtagpki/server/rest/PKIExceptionMapper.java
+++ b/base/server/cms/src/org/dogtagpki/server/rest/PKIExceptionMapper.java
@@ -2,6 +2,7 @@ package org.dogtagpki.server.rest;
 
 import javax.ws.rs.core.Context;
 import javax.ws.rs.core.HttpHeaders;
+import javax.ws.rs.core.MediaType;
 import javax.ws.rs.core.Response;
 import javax.ws.rs.ext.ExceptionMapper;
 import javax.ws.rs.ext.Provider;
@@ -17,10 +18,26 @@ public class PKIExceptionMapper implements ExceptionMapper<PKIException> {
 
     public Response toResponse(PKIException exception) {
         // convert PKIException into HTTP response
+
+        // The exception Data can only be serialised as XML or JSON,
+        // so coerce the response content type to one of these.
+        // Default to XML, but consider the Accept header.
+        MediaType contentType = MediaType.APPLICATION_XML_TYPE;
+        for (MediaType acceptType : headers.getAcceptableMediaTypes()) {
+            if (acceptType.isCompatible(MediaType.APPLICATION_XML_TYPE)) {
+                contentType = MediaType.APPLICATION_XML_TYPE;
+                break;
+            }
+            if (acceptType.isCompatible(MediaType.APPLICATION_JSON_TYPE)) {
+                contentType = MediaType.APPLICATION_JSON_TYPE;
+                break;
+            }
+        }
+
         return Response
                 .status(exception.getCode())
                 .entity(exception.getData())
-                .type(PKIService.getResponseFormat(headers))
+                .type(contentType)
                 .build();
     }
 }
-- 
1.8.3.1