--- httpd-2.2.17/modules/proxy/mod_proxy_ajp.c.orig	2010-08-25 16:16:25.000000000 +0200
+++ httpd-2.2.17/modules/proxy/mod_proxy_ajp.c.orig	2011-03-18 13:47:52.000000000 +0100
@@ -188,10 +188,12 @@ static int ap_proxy_ajp_request(apr_pool
     proxy_server_conf *psf =
     ap_get_module_config(r->server->module_config, &proxy_module);
     apr_size_t maxsize = AJP_MSG_BUFFER_SZ;
     int send_body = 0;
     apr_off_t content_length = 0;
+    int original_status = r->status;
+    const char *original_status_line = r->status_line;
 
     if (psf->io_buffer_size_set)
        maxsize = psf->io_buffer_size;
     if (maxsize > AJP_MAX_BUFFER_SZ)
        maxsize = AJP_MAX_BUFFER_SZ;
@@ -428,16 +430,31 @@ static int ap_proxy_ajp_request(apr_pool
                 /* AJP13_SEND_HEADERS: process them */
                 status = ajp_parse_header(r, conf, conn->data);
                 if (status != APR_SUCCESS) {
                     backend_failed = 1;
                 }
+                else if ((r->status == 401) && psf->error_override) {
+                    const char *buf;
+                    const char *wa = "WWW-Authenticate";
+                    if ((buf = apr_table_get(r->headers_out, wa))) {
+                        apr_table_set(r->err_headers_out, wa, buf);
+                    } else {
+                        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
+                                     "ap_proxy_ajp_request: origin server "
+                                     "sent 401 without WWW-Authenticate header");
+                    }
+                }
                 headers_sent = 1;
                 break;
             case CMD_AJP13_SEND_BODY_CHUNK:
                 /* AJP13_SEND_BODY_CHUNK: piece of data */
                 status = ajp_parse_data(r, conn->data, &size, &send_body_chunk_buff);
                 if (status == APR_SUCCESS) {
+                    /* If we are overriding the errors, we can't put the content
+                     * of the page into the brigade.
+                     */
+                    if (!psf->error_override || !ap_is_HTTP_ERROR(r->status)) {
                     /* AJP13_SEND_BODY_CHUNK with zero length
                      * is explicit flush message
                      */
                     if (size == 0) {
                         if (headers_sent) {
@@ -450,10 +467,21 @@ static int ap_proxy_ajp_request(apr_pool
                         }
                     }
                     else {
                         apr_status_t rv;
 
+                            /* Handle the case where the error document is itself reverse
+                             * proxied and was successful. We must maintain any previous
+                             * error status so that an underlying error (eg HTTP_NOT_FOUND)
+                             * doesn't become an HTTP_OK.
+                             */
+                            if (psf->error_override && !ap_is_HTTP_ERROR(r->status)
+                                    && ap_is_HTTP_ERROR(original_status)) {
+                                r->status = original_status;
+                                r->status_line = original_status_line;
+                            }
+
                         e = apr_bucket_transient_create(send_body_chunk_buff, size,
                                                     r->connection->bucket_alloc);
                         APR_BRIGADE_INSERT_TAIL(output_brigade, e);
 
                         if ((conn->worker->flush_packets == flush_on) ||
@@ -478,25 +506,32 @@ static int ap_proxy_ajp_request(apr_pool
                         output_failed = 1;
                     }
                     data_sent = 1;
                     apr_brigade_cleanup(output_brigade);
                 }
+                }
                 else {
                     backend_failed = 1;
                 }
                 break;
             case CMD_AJP13_END_RESPONSE:
+                /* If we are overriding the errors, we must not send anything to
+                 * the client, especially as the brigade already contains headers.
+                 * So do nothing here, and it will be cleaned up below.
+                 */
+                if (!psf->error_override || !ap_is_HTTP_ERROR(r->status)) {
                 e = apr_bucket_eos_create(r->connection->bucket_alloc);
                 APR_BRIGADE_INSERT_TAIL(output_brigade, e);
                 if (ap_pass_brigade(r->output_filters,
                                     output_brigade) != APR_SUCCESS) {
                     ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                                   "proxy: error processing end");
                     output_failed = 1;
                 }
                 /* XXX: what about flush here? See mod_jk */
                 data_sent = 1;
+                }
                 request_ended = 1;
                 break;
             default:
                 backend_failed = 1;
                 break;
@@ -567,12 +602,22 @@ static int ap_proxy_ajp_request(apr_pool
     else {
         ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
                      "proxy: got response from %pI (%s)",
                      conn->worker->cp->addr,
                      conn->worker->hostname);
+
+        if (psf->error_override && ap_is_HTTP_ERROR(r->status)) {
+            /* clear r->status for override error, otherwise ErrorDocument
+             * thinks that this is a recursive error, and doesn't find the
+             * custom error page
+             */
+            rv = r->status;
+            r->status = HTTP_OK;
+        } else {
         rv = OK;
     }
+    }
 
     if (backend_failed) {
         ap_log_error(APLOG_MARK, APLOG_ERR, status, r->server,
                      "proxy: dialog to %pI (%s) failed",
                      conn->worker->cp->addr,