--- httpd-2.2.4/modules/dav/main/util.c	2006-07-12 05:38:44.000000000 +0200
+++ httpd-2.2.4-new/modules/dav/main/util.c	2007-07-26 18:30:01.000000000 +0200
@@ -19,6 +19,7 @@
 **  - various utilities, repository-independent
 */
 
+#include "apr_date.h"
 #include "apr_strings.h"
 #include "apr_lib.h"
 
@@ -1404,6 +1405,141 @@
     return NULL;
 }
 
+/** This is a copy of ap_meets_conditions with this changes:
+  * - additional parameter resource
+  * - use (*resource->hooks->getetag)(resource) to get etag, as
+  *   apr_table_get(r->headers_out, "ETag") does not work in this context.
+  * - "If-None-Match: *" evaluates to TRUE if the resource does not exist.
+  * - "If-Match: *" evaluates to TRUE if the resource exists.
+  */
+static int dav_meets_conditions(request_rec *r, dav_resource *resource)
+{
+    const char *etag;
+    const char *if_match, *if_modified_since, *if_unmodified, *if_nonematch;
+    apr_time_t tmp_time;
+    apr_int64_t mtime;
+    int not_modified = 0;
+
+    /* Check for conditional requests --- note that we only want to do
+     * this if we are successful so far and we are not processing a
+     * subrequest or an ErrorDocument.
+     *
+     * The order of the checks is important, since ETag checks are supposed
+     * to be more accurate than checks relative to the modification time.
+     * However, not all documents are guaranteed to *have* ETags, and some
+     * might have Last-Modified values w/o ETags, so this gets a little
+     * complicated.
+     */
+
+    if (!ap_is_HTTP_SUCCESS(r->status) || r->no_local_copy) {
+        return OK;
+    }
+
+    etag = (*resource->hooks->getetag)(resource);
+
+    /* All of our comparisons must be in seconds, because that's the
+     * highest time resolution the HTTP specification allows.
+     */
+    /* XXX: we should define a "time unset" constant */
+    tmp_time = ((r->mtime != 0) ? r->mtime : apr_time_now());
+    mtime =  apr_time_sec(tmp_time);
+
+    /* If an If-Match request-header field was given
+     * AND ( the field value is not "*" (meaning match anything)
+     *       OR the resource does not exist )
+     * AND if our strong ETag does not match any entity tag in that field,
+     *     respond with a status of 412 (Precondition Failed).
+     */
+    if ((if_match = apr_table_get(r->headers_in, "If-Match")) != NULL) {
+        if (!(if_match[0] == '*' && resource->exists)
+            && (etag == NULL || etag[0] == 'W'
+                || !ap_find_list_item(r->pool, if_match, etag))) {
+            return HTTP_PRECONDITION_FAILED;
+        }
+    }
+    else {
+        /* Else if a valid If-Unmodified-Since request-header field was given
+         * AND the requested resource has been modified since the time
+         * specified in this field, then the server MUST
+         *     respond with a status of 412 (Precondition Failed).
+         */
+        if_unmodified = apr_table_get(r->headers_in, "If-Unmodified-Since");
+        if (if_unmodified != NULL) {
+            apr_time_t ius = apr_date_parse_http(if_unmodified);
+
+            if ((ius != APR_DATE_BAD) && (mtime > apr_time_sec(ius))) {
+                return HTTP_PRECONDITION_FAILED;
+            }
+        }
+    }
+
+    /* If an If-None-Match request-header field was given
+     * AND the field value is "*" (meaning match anything)
+     * AND the resource exists
+     *     OR our ETag matches any of the entity tags in that field, fail.
+     *
+     * If the request method was GET or HEAD, failure means the server
+     *    SHOULD respond with a 304 (Not Modified) response.
+     * For all other request methods, failure means the server MUST
+     *    respond with a status of 412 (Precondition Failed).
+     *
+     * GET or HEAD allow weak etag comparison, all other methods require
+     * strong comparison.  We can only use weak if it's not a range request.
+     */
+    if_nonematch = apr_table_get(r->headers_in, "If-None-Match");
+    if (if_nonematch != NULL) {
+        if (r->method_number == M_GET) {
+            if (if_nonematch[0] == '*') {
+                not_modified = 1;
+            }
+            else if (etag != NULL) {
+                if (apr_table_get(r->headers_in, "Range")) {
+                    not_modified = etag[0] != 'W'
+                                   && ap_find_list_item(r->pool,
+                                                        if_nonematch, etag);
+                }
+                else {
+                    not_modified = ap_find_list_item(r->pool,
+                                                     if_nonematch, etag);
+                }
+            }
+        }
+        else if ((if_nonematch[0] == '*' && resource->exists)
+                 || (etag != NULL
+                     && ap_find_list_item(r->pool, if_nonematch, etag))) {
+            return HTTP_PRECONDITION_FAILED;
+        }
+    }
+
+    /* If a valid If-Modified-Since request-header field was given
+     * AND it is a GET or HEAD request
+     * AND the requested resource has not been modified since the time
+     * specified in this field, then the server MUST
+     *    respond with a status of 304 (Not Modified).
+     * A date later than the server's current request time is invalid.
+     */
+    if (r->method_number == M_GET
+        && (not_modified || !if_nonematch)
+        && (if_modified_since =
+              apr_table_get(r->headers_in,
+                            "If-Modified-Since")) != NULL) {
+        apr_time_t ims_time;
+        apr_int64_t ims, reqtime;
+
+        ims_time = apr_date_parse_http(if_modified_since);
+        ims = apr_time_sec(ims_time);
+        reqtime = apr_time_sec(r->request_time);
+
+        not_modified = ims >= mtime && ims <= reqtime;
+    }
+
+    if (not_modified) {
+        return HTTP_NOT_MODIFIED;
+    }
+
+    return OK;
+}
+
 /*
 ** dav_validate_request:  Validate if-headers (and check for locks) on:
 **    (1) r->filename @ depth;
@@ -1450,9 +1586,9 @@
         *response = NULL;
 
     /* Do the standard checks for conditional requests using
-     * If-..-Since, If-Match etc */
-    if ((result = ap_meets_conditions(r)) != OK) {
-        /* ### fix this up... how? */
+     * If-..-Since, If-Match etc
+     * use dav_meets_conditions instead of ap_meets_conditions. */
+    if ((result = dav_meets_conditions(r, resource)) != OK) {
         return dav_new_error(r->pool, result, 0, NULL);
     }