If-Unmodified-Since

[Igor Sysoev]

On Thu, Dec 02, 2010 at 03:28:27PM +0300, Igor Sysoev wrote:

> On Wed, Dec 01, 2010 at 07:56:56PM -0500, Jeff Mitchell wrote:
> 
> > It appears from documentation and Googling that nginx supports the
> > If-Modified-Since header but not the If-Unmodified-Since header; are
> > there any plans to add support?
> 
> nginx does not support If-Unmodified-Since.
> I believe it's easy to add it, but are clients which support the header ?

The attached patch adds If-Unmodified-Since support.


-- 
Igor Sysoev
http://sysoev.ru/en/
-------------- next part --------------
Index: src/http/ngx_http_request.c
===================================================================
--- src/http/ngx_http_request.c	(revision 3133)
+++ src/http/ngx_http_request.c	(working copy)
@@ -88,6 +88,10 @@
                  offsetof(ngx_http_headers_in_t, if_modified_since),
                  ngx_http_process_unique_header_line },
 
+    { ngx_string("If-Unmodified-Since"),
+                 offsetof(ngx_http_headers_in_t, if_unmodified_since),
+                 ngx_http_process_unique_header_line },
+
     { ngx_string("User-Agent"), offsetof(ngx_http_headers_in_t, user_agent),
                  ngx_http_process_user_agent },
 
Index: src/http/ngx_http_request.h
===================================================================
--- src/http/ngx_http_request.h	(revision 3133)
+++ src/http/ngx_http_request.h	(working copy)
@@ -167,6 +167,7 @@
     ngx_table_elt_t                  *host;
     ngx_table_elt_t                  *connection;
     ngx_table_elt_t                  *if_modified_since;
+    ngx_table_elt_t                  *if_unmodified_since;
     ngx_table_elt_t                  *user_agent;
     ngx_table_elt_t                  *referer;
     ngx_table_elt_t                  *content_length;
Index: src/http/modules/ngx_http_not_modified_filter_module.c
===================================================================
--- src/http/modules/ngx_http_not_modified_filter_module.c	(revision 3133)
+++ src/http/modules/ngx_http_not_modified_filter_module.c	(working copy)
@@ -9,7 +9,8 @@
 #include <ngx_http.h>
 
 
-
+static ngx_int_t ngx_http_test_precondition(ngx_http_request_t *r);
+static ngx_int_t ngx_http_test_not_modified(ngx_http_request_t *r);
 static ngx_int_t ngx_http_not_modified_filter_init(ngx_conf_t *cf);
 
 
@@ -50,17 +51,51 @@
 static ngx_int_t
 ngx_http_not_modified_header_filter(ngx_http_request_t *r)
 {
-    time_t                     ims;
-    ngx_http_core_loc_conf_t  *clcf;
-
     if (r->headers_out.status != NGX_HTTP_OK
         || r != r->main
-        || r->headers_in.if_modified_since == NULL
         || r->headers_out.last_modified_time == -1)
     {
         return ngx_http_next_header_filter(r);
     }
+ 
+    if (r->headers_in.if_unmodified_since) {
+        return ngx_http_test_precondition(r);
+    }
+ 
+    if (r->headers_in.if_modified_since) {
+        return ngx_http_test_not_modified(r);
+    }
 
+    return ngx_http_next_header_filter(r);
+}
+
+
+static ngx_int_t
+ngx_http_test_precondition(ngx_http_request_t *r)
+{
+    time_t  iums;
+
+    iums = ngx_http_parse_time(r->headers_in.if_unmodified_since->value.data,
+                               r->headers_in.if_unmodified_since->value.len);
+
+    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                 "http iums:%d lm:%d", iums, r->headers_out.last_modified_time);
+
+    if (iums >= r->headers_out.last_modified_time) {
+        return ngx_http_next_header_filter(r);
+    }
+
+    return ngx_http_filter_finalize_request(r, NULL,
+                                            NGX_HTTP_PRECONDITION_FAILED);
+}
+
+
+static ngx_int_t
+ngx_http_test_not_modified(ngx_http_request_t *r)
+{
+    time_t                     ims;
+    ngx_http_core_loc_conf_t  *clcf;
+
     clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
 
     if (clcf->if_modified_since == NGX_HTTP_IMS_OFF) {