merge r3309, r3314, r3315, r3380:

gzip headers related fixes:

*) remove "Content-Encoding: gzip" in 304 response
   sent by ngx_http_gzip_static_module
*) refactor gzip_vary handling
*) test r->header_only last, since it's not actually
   frequent here: 304 and HEAD responses are not set it before the filter

src/http/modules/ngx_http_gzip_filter_module.c

@@ -246,17 +246,27 @@ ngx_http_gzip_header_filter(ngx_http_request_t *r)
         || (r->headers_out.status != NGX_HTTP_OK
             && r->headers_out.status != NGX_HTTP_FORBIDDEN
             && r->headers_out.status != NGX_HTTP_NOT_FOUND)
-        || r->header_only
         || (r->headers_out.content_encoding
             && 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)
+        || r->header_only)
     {
         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;

src/http/modules/ngx_http_gzip_static_module.c

@@ -144,7 +144,6 @@ ngx_http_gzip_static_handler(ngx_http_request_t *r)
         case NGX_ENOTDIR:
         case NGX_ENAMETOOLONG:
 
-            r->gzip = 0;
             return NGX_DECLINED;
 
         case NGX_EACCES:
@@ -164,6 +163,8 @@ ngx_http_gzip_static_handler(ngx_http_request_t *r)
         return NGX_DECLINED;
     }
 
+    r->gzip_vary = 1;
+
     if (rc != NGX_OK) {
         return NGX_DECLINED;
     }

src/http/modules/ngx_http_not_modified_filter_module.c

@@ -88,6 +88,11 @@ ngx_http_not_modified_header_filter(ngx_http_request_t *r)
     ngx_http_clear_content_length(r);
     ngx_http_clear_accept_ranges(r);
 
+    if (r->headers_out.content_encoding) {
+        r->headers_out.content_encoding->hash = 0;
+        r->headers_out.content_encoding = NULL;
+    }
+
     return ngx_http_next_header_filter(r);
 }
 

src/http/ngx_http_core_module.c

@@ -773,7 +773,11 @@ ngx_http_handler(ngx_http_request_t *r)
     }
 
     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);
@@ -1860,15 +1864,7 @@ ngx_http_gzip_ok(ngx_http_request_t *r)
     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
@@ -2003,7 +1999,7 @@ ok:
 
 #endif
 
-    r->gzip = 1;
+    r->gzip_ok = 1;
 
     return NGX_OK;
 }

src/http/ngx_http_header_filter_module.c

@@ -399,8 +399,13 @@ ngx_http_header_filter(ngx_http_request_t *r)
     }
 
 #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 @@ ngx_http_header_filter(ngx_http_request_t *r)
     }
 
 #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);
     }

src/http/ngx_http_request.h

@@ -451,7 +451,12 @@ struct ngx_http_request_s {
 #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;