# HG changeset patch
# User Maxim Dounin <mdounin@mdounin.ru>
# Date 1403735701 -14400
# Node ID c95d7882dfc9ff90ee161328747114b6b54667a5
# Parent  44b9ab7752e3decaadeb374db410db215a262d55
Upstream: cache revalidation using If-None-Match.

diff --git a/src/http/modules/ngx_http_fastcgi_module.c b/src/http/modules/ngx_http_fastcgi_module.c
--- a/src/http/modules/ngx_http_fastcgi_module.c
+++ b/src/http/modules/ngx_http_fastcgi_module.c
@@ -573,7 +573,7 @@ static ngx_keyval_t  ngx_http_fastcgi_ca
     { ngx_string("HTTP_IF_MODIFIED_SINCE"),
       ngx_string("$upstream_cache_last_modified") },
     { ngx_string("HTTP_IF_UNMODIFIED_SINCE"), ngx_string("") },
-    { ngx_string("HTTP_IF_NONE_MATCH"), ngx_string("") },
+    { ngx_string("HTTP_IF_NONE_MATCH"), ngx_string("$upstream_cache_etag") },
     { ngx_string("HTTP_IF_MATCH"), ngx_string("") },
     { ngx_string("HTTP_RANGE"), ngx_string("") },
     { ngx_string("HTTP_IF_RANGE"), ngx_string("") },
diff --git a/src/http/modules/ngx_http_proxy_module.c b/src/http/modules/ngx_http_proxy_module.c
--- a/src/http/modules/ngx_http_proxy_module.c
+++ b/src/http/modules/ngx_http_proxy_module.c
@@ -677,7 +677,7 @@ static ngx_keyval_t  ngx_http_proxy_cach
     { ngx_string("If-Modified-Since"),
       ngx_string("$upstream_cache_last_modified") },
     { ngx_string("If-Unmodified-Since"), ngx_string("") },
-    { ngx_string("If-None-Match"), ngx_string("") },
+    { ngx_string("If-None-Match"), ngx_string("$upstream_cache_etag") },
     { ngx_string("If-Match"), ngx_string("") },
     { ngx_string("Range"), ngx_string("") },
     { ngx_string("If-Range"), ngx_string("") },
diff --git a/src/http/modules/ngx_http_scgi_module.c b/src/http/modules/ngx_http_scgi_module.c
--- a/src/http/modules/ngx_http_scgi_module.c
+++ b/src/http/modules/ngx_http_scgi_module.c
@@ -379,7 +379,7 @@ static ngx_keyval_t  ngx_http_scgi_cache
     { ngx_string("HTTP_IF_MODIFIED_SINCE"),
       ngx_string("$upstream_cache_last_modified") },
     { ngx_string("HTTP_IF_UNMODIFIED_SINCE"), ngx_string("") },
-    { ngx_string("HTTP_IF_NONE_MATCH"), ngx_string("") },
+    { ngx_string("HTTP_IF_NONE_MATCH"), ngx_string("$upstream_cache_etag") },
     { ngx_string("HTTP_IF_MATCH"), ngx_string("") },
     { ngx_string("HTTP_RANGE"), ngx_string("") },
     { ngx_string("HTTP_IF_RANGE"), ngx_string("") },
diff --git a/src/http/modules/ngx_http_uwsgi_module.c b/src/http/modules/ngx_http_uwsgi_module.c
--- a/src/http/modules/ngx_http_uwsgi_module.c
+++ b/src/http/modules/ngx_http_uwsgi_module.c
@@ -507,7 +507,7 @@ static ngx_keyval_t  ngx_http_uwsgi_cach
     { ngx_string("HTTP_IF_MODIFIED_SINCE"),
       ngx_string("$upstream_cache_last_modified") },
     { ngx_string("HTTP_IF_UNMODIFIED_SINCE"), ngx_string("") },
-    { ngx_string("HTTP_IF_NONE_MATCH"), ngx_string("") },
+    { ngx_string("HTTP_IF_NONE_MATCH"), ngx_string("$upstream_cache_etag") },
     { ngx_string("HTTP_IF_MATCH"), ngx_string("") },
     { ngx_string("HTTP_RANGE"), ngx_string("") },
     { ngx_string("HTTP_IF_RANGE"), ngx_string("") },
diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -19,6 +19,8 @@ static ngx_int_t ngx_http_upstream_cache
     ngx_http_variable_value_t *v, uintptr_t data);
 static ngx_int_t ngx_http_upstream_cache_last_modified(ngx_http_request_t *r,
     ngx_http_variable_value_t *v, uintptr_t data);
+static ngx_int_t ngx_http_upstream_cache_etag(ngx_http_request_t *r,
+    ngx_http_variable_value_t *v, uintptr_t data);
 #endif
 
 static void ngx_http_upstream_init_request(ngx_http_request_t *r);
@@ -367,6 +369,10 @@ static ngx_http_variable_t  ngx_http_ups
       ngx_http_upstream_cache_last_modified, 0,
       NGX_HTTP_VAR_NOCACHEABLE|NGX_HTTP_VAR_NOHASH, 0 },
 
+    { ngx_string("upstream_cache_etag"), NULL,
+      ngx_http_upstream_cache_etag, 0,
+      NGX_HTTP_VAR_NOCACHEABLE|NGX_HTTP_VAR_NOHASH, 0 },
+
 #endif
 
     { ngx_null_string, NULL, NULL, 0, 0, 0 }
@@ -4792,6 +4798,29 @@ ngx_http_upstream_cache_last_modified(ng
     return NGX_OK;
 }
 
+
+static ngx_int_t
+ngx_http_upstream_cache_etag(ngx_http_request_t *r,
+    ngx_http_variable_value_t *v, uintptr_t data)
+{
+    if (r->upstream == NULL
+        || !r->upstream->conf->cache_revalidate
+        || r->upstream->cache_status != NGX_HTTP_CACHE_EXPIRED
+        || r->cache->etag.len == 0)
+    {
+        v->not_found = 1;
+        return NGX_OK;
+    }
+
+    v->valid = 1;
+    v->no_cacheable = 0;
+    v->not_found = 0;
+    v->len = r->cache->etag.len;
+    v->data = r->cache->etag.data;
+
+    return NGX_OK;
+}
+
 #endif