WWW-Authenticate header lost when reverse-proxying

[rr...@fscinternet.com]

(Correction to previous posting: This error *only* occurs with 
`ProxyErrorOverride On'.)


When operating as a reverse proxy, with `ProxyErrorOverride On', 
mod_proxy incorrectly fails to pass through the WWW-Authenticate 
response header on 401 responses.

It seems the problem is that ap_send_error_response() clears 
r->headers_out, while ap_proxy_http_process_response() does not copy 
the WWW-Authenticate header into r->err_headers_out.

A patch which fixes this follows.  Note that this has NOT received 
extensive testing.

*** modules/proxy/proxy_http.c.orig     Thu Sep 19 14:47:51 2002
--- modules/proxy/proxy_http.c  Thu Sep 19 17:38:36 2002
***************
*** 863,868 ****
--- 863,879 ----
              }
          }
  
+       if ((r->status == 401) && (conf->error_override != 0)) {
+           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,
+                            "proxy: origin server sent 401 without w-a 
header");
+           }
+       }
+ 
          r->sent_bodyct = 1;
          /* Is it an HTTP/0.9 response? If so, send the extra data */
          if (backasswards) {
***************
*** 969,974 ****
--- 980,986 ----
               */
              int status = r->status;
              r->status = HTTP_OK;
+           ap_discard_request_body(rp);
              return status;
          }
      } else