[PATCH 1.3] Proxied Server:/Date: headers

[William A. Rowe, Jr.]

I'd worked with some interesting java and cgi code which implements
proxy behavior, as opposed to using a compiled-in module such as
mod_proxy.  In order to properly pass on the Server: and Date: headers
(which are owned by the origin server), this patch tests for the presence
of a Via: header, indicating the response is proxied.

If neither r->proxyreq nor a 'Via:' header exist, the server still overrides
the Server: and Date: responses, per RFC.

Comments appreciated.

Bill
--- src/main/http_protocol.c    15 Apr 2004 15:51:51 -0000      1.335
+++ src/main/http_protocol.c    28 May 2004 18:00:10 -0000
@@ -1544,6 +1544,8 @@
 API_EXPORT(void) ap_basic_http_header(request_rec *r)
 {
     char *protocol;
+    const char *datestr = NULL;
+    const char *server = NULL;
 
     if (r->assbackwards)
         return;
@@ -1569,20 +1571,29 @@
     /* output the HTTP/1.x Status-Line */
     ap_rvputs(r, protocol, " ", r->status_line, CRLF, NULL);
 
-    /* output the date header */
-    ap_send_header_field(r, "Date", ap_gm_timestr_822(r->pool, r->request_time));
+    /* keep the set-by-proxy date header, otherwise
+     * generate a new server header */
+    if (r->proxyreq || ap_table_get(r->headers_out, "Via")) {
+        datestr = ap_table_get(r->headers_out, "Date");
+
+        if (datestr && (ap_parseHTTPdate(datestr) == BAD_DATE)) {
+            datestr = NULL;
+        }
+    }
+    if (!datestr || !*datestr) {
+        datestr = ap_gm_timestr_822(r->pool, r->request_time);
+    }
+    ap_send_header_field(r, "Date", datestr);
 
     /* keep the set-by-proxy server header, otherwise
      * generate a new server header */
-    if (r->proxyreq) {
-        const char *server = ap_table_get(r->headers_out, "Server");
-        if (server) {
-            ap_send_header_field(r, "Server", server);
-        }
+    if (r->proxyreq || ap_table_get(r->headers_out, "Via")) {
+        server = ap_table_get(r->headers_out, "Server");
     }
-    else {
-        ap_send_header_field(r, "Server", ap_get_server_version());
+    if (!server || !*server) {
+        server = ap_get_server_version();
     }
+    ap_send_header_field(r, "Server", server);
 
     /* unset so we don't send them again */
     ap_table_unset(r->headers_out, "Date");        /* Avoid bogosity */