refactor gzip_vary handling

diff --git a/src/http/modules/ngx_http_gzip_filter_module.c b/src/http/modules/ngx_http_gzip_filter_module.c
index 62b430b..4c0c0d2 100644
--- a/src/http/modules/ngx_http_gzip_filter_module.c
+++ b/src/http/modules/ngx_http_gzip_filter_module.c

@@ -251,12 +251,22 @@
             && r->headers_out.content_encoding->value.len)
         || (r->headers_out.content_length_n != -1
             && r->headers_out.content_length_n < conf->min_length)
-        || ngx_http_test_content_type(r, &conf->types) == NULL
-        || ngx_http_gzip_ok(r) != NGX_OK)
+        || ngx_http_test_content_type(r, &conf->types) == NULL)
     {
         return ngx_http_next_header_filter(r);
     }
 
+    r->gzip_vary = 1;
+
+    if (!r->gzip_tested) {
+        if (ngx_http_gzip_ok(r) != NGX_OK) {
+            return ngx_http_next_header_filter(r);
+        }
+
+    } else if (!r->gzip_ok) {
+        return ngx_http_next_header_filter(r);
+    }
+
     ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_gzip_ctx_t));
     if (ctx == NULL) {
         return NGX_ERROR;

diff --git a/src/http/modules/ngx_http_gzip_static_module.c b/src/http/modules/ngx_http_gzip_static_module.c
index cff23e0..a928d16 100644
--- a/src/http/modules/ngx_http_gzip_static_module.c
+++ b/src/http/modules/ngx_http_gzip_static_module.c

@@ -145,7 +145,6 @@
         case NGX_ENOTDIR:
         case NGX_ENAMETOOLONG:
 
-            r->gzip = 0;
             return NGX_DECLINED;
 
         case NGX_EACCES:
@@ -165,6 +164,8 @@
         return NGX_DECLINED;
     }
 
+    r->gzip_vary = 1;
+
     if (rc != NGX_OK) {
         return NGX_DECLINED;
     }

diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
index 9cce2d5..ee0864c 100644
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c

@@ -812,7 +812,11 @@
     }
 
     r->valid_location = 1;
-    r->gzip = 0;
+#if (NGX_HTTP_GZIP)
+    r->gzip_tested = 0;
+    r->gzip_ok = 0;
+    r->gzip_vary = 0;
+#endif
 
     r->write_event_handler = ngx_http_core_run_phases;
     ngx_http_core_run_phases(r);
@@ -1891,15 +1895,7 @@
     ngx_table_elt_t           *e, *d;
     ngx_http_core_loc_conf_t  *clcf;
 
-    if (r->gzip == 1) {
-        return NGX_OK;
-    }
-
-    if (r->gzip == 2) {
-        return NGX_DECLINED;
-    }
-
-    r->gzip = 2;
+    r->gzip_tested = 1;
 
     if (r != r->main
         || r->headers_in.accept_encoding == NULL
@@ -2034,7 +2030,7 @@
 
 #endif
 
-    r->gzip = 1;
+    r->gzip_ok = 1;
 
     return NGX_OK;
 }

diff --git a/src/http/ngx_http_header_filter_module.c b/src/http/ngx_http_header_filter_module.c
index 9044c40..0f6f173 100644
--- a/src/http/ngx_http_header_filter_module.c
+++ b/src/http/ngx_http_header_filter_module.c

@@ -399,8 +399,13 @@
     }
 
 #if (NGX_HTTP_GZIP)
-    if (r->gzip && clcf->gzip_vary) {
-        len += sizeof("Vary: Accept-Encoding" CRLF) - 1;
+    if (r->gzip_vary) {
+        if (clcf->gzip_vary) {
+            len += sizeof("Vary: Accept-Encoding" CRLF) - 1;
+
+        } else {
+            r->gzip_vary = 0;
+        }
     }
 #endif
 
@@ -559,7 +564,7 @@
     }
 
 #if (NGX_HTTP_GZIP)
-    if (r->gzip && clcf->gzip_vary) {
+    if (r->gzip_vary) {
         b->last = ngx_cpymem(b->last, "Vary: Accept-Encoding" CRLF,
                              sizeof("Vary: Accept-Encoding" CRLF) - 1);
     }

diff --git a/src/http/ngx_http_request.h b/src/http/ngx_http_request.h
index 8f34815..ade15a5 100644
--- a/src/http/ngx_http_request.h
+++ b/src/http/ngx_http_request.h

@@ -457,7 +457,12 @@
 #if (NGX_HTTP_CACHE)
     unsigned                          cached:1;
 #endif
-    unsigned                          gzip:2;
+
+#if (NGX_HTTP_GZIP)
+    unsigned                          gzip_tested:1;
+    unsigned                          gzip_ok:1;
+    unsigned                          gzip_vary:1;
+#endif
 
     unsigned                          proxy:1;
     unsigned                          bypass_cache:1;