* squid-2.3.DEVEL3.age.patch *

Mon Jan  3 05:44:13 CET 2000
Modified Files in squid/src
	store.c 

Corrected age calculation to take into account any existing Age header
added by upstream caches.

-----------------------------------------------------------------

Mon Jan  3 05:46:06 CET 2000
Modified Files in squid/src
	client_side.c 

Added a small workaround for IE browsers who hang on certain replies
with a "Age: 0" header.


Index: squid/src/client_side.c
diff -u squid/src/client_side.c:1.1.1.46.2.7 squid/src/client_side.c:1.1.1.46.2.8
--- squid/src/client_side.c:1.1.1.46.2.7	Sat Dec 25 10:45:22 1999
+++ squid/src/client_side.c	Mon Jan  3 05:46:04 2000
@@ -1180,20 +1180,29 @@
     if (request->range)
 	clientBuildRangeHeader(http, rep);
     /*
-     * Add Age header, not that our header must replace Age headers
-     * from other caches if any
+     * Add a estimated Age header on cache hits.
      */
-    if (http->entry->timestamp > 0) {
+    if (is_hit) {
+    	/*
+	 * Remove any existing Age header sent by upstream caches
+	 * (note that the existing header is passed along unmodified
+	 * on cache misses)
+	 */
 	httpHeaderDelById(hdr, HDR_AGE);
-	/*
-	 * we do not follow HTTP/1.1 precisely here becuase we rely
-	 * on Date header when computing entry->timestamp; we should
-	 * be using _request_ time if Date header is not available
-	 * or if it is out of sync
+    	/*
+	 * This adds the calculated object age. Note that the details of the
+	 * age calculation is performed by adjusting the timestamp in
+	 * storeTimestampsSet(), not here.
+	 *
+	 * BROWSER WORKAROUND: IE sometimes hangs when receiving a 0 Age
+	 * header, so don't use it unless there is a age to report. Please
+	 * note that Age is only used to make a conservative estimation of
+	 * the objects age, so a Age: 0 header does not add any useful
+	 * information to the reply in any case.
 	 */
-	httpHeaderPutInt(hdr, HDR_AGE,
-	    http->entry->timestamp <= squid_curtime ?
-	    squid_curtime - http->entry->timestamp : 0);
+	if (http->entry->timestamp < squid_curtime)
+	    httpHeaderPutInt(hdr, HDR_AGE,
+		squid_curtime - http->entry->timestamp);
     }
     /* Append X-Cache */
     httpHeaderPutStrf(hdr, HDR_X_CACHE, "%s from %s",
Index: squid/src/store.c
diff -u squid/src/store.c:1.1.1.43.2.3 squid/src/store.c:1.1.1.43.2.4
--- squid/src/store.c:1.1.1.43.2.3	Sun Nov 21 16:19:57 1999
+++ squid/src/store.c	Mon Jan  3 05:44:12 2000
@@ -1256,9 +1256,24 @@
 {
     const HttpReply *reply = entry->mem_obj->reply;
     time_t served_date = reply->date;
+    int age = httpHeaderGetInt(&reply->header, HDR_AGE);
+    /*
+     * The timestamp calculations below tries to mimic the properties
+     * of the age calculation in RFC2616 section 13.2.3. The implementaion
+     * isn't complete, and the most notable exception from the RFC is that
+     * this does not account for response_delay, but it probably does
+     * not matter much as this is calculated immediately when the headers
+     * are received, not when the whole response has been received.
+     */
     /* make sure that 0 <= served_date <= squid_curtime */
     if (served_date < 0 || served_date > squid_curtime)
 	served_date = squid_curtime;
+    /*
+     * Compensate with Age header if origin server clock is ahead of us
+     * and there is a cache in between us and the origin server
+     */
+    if (age > squid_curtime - served_date)
+    	served_date = squid_curtime - age;
     entry->expires = reply->expires;
     entry->lastmod = reply->last_modified;
     entry->timestamp = served_date;