# HG changeset patch # User Roman Arutyunyan # Date 1425314833 -10800 # Node ID 174512857ccff69715ac89fa5f3841a1e0e4d0c9 # Parent 435ee290c2e14eb4ccb155549f8e63841af56496 Cache: do not inherit last_modified and etag from stale response. When replacing a stale cache entry, its last_modified and etag could be inherited from the old entry if the response code is not 200 or 206. Moreover, etag could be inherited with any response code if it's missing in the new response. As a result, the cache entry is left with invalid last_modified or etag which could lead to broken revalidation. For example, when a file is deleted from backend, its last_modified is copied to the new 404 cache entry and is used later for revalidation. Once the old file appears again with its original timestamp, revalidation succeeds and the cached 404 response is sent to client instead of the file. The problem appeared with etags in 44b9ab7752e3 (1.7.3) and affected last_modified in 1573fc7875fa (1.7.9). diff --git a/src/http/ngx_http_file_cache.c b/src/http/ngx_http_file_cache.c --- a/src/http/ngx_http_file_cache.c +++ b/src/http/ngx_http_file_cache.c @@ -181,8 +181,6 @@ ngx_http_file_cache_new(ngx_http_request c->file.log = r->connection->log; c->file.fd = NGX_INVALID_FILE; - c->last_modified = -1; - return NGX_OK; } 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 @@ -2635,7 +2635,14 @@ ngx_http_upstream_send_response(ngx_http if (u->headers_in.etag) { r->cache->etag = u->headers_in.etag->value; + + } else { + ngx_str_null(&r->cache->etag); } + + } else { + r->cache->last_modified = -1; + ngx_str_null(&r->cache->etag); } if (ngx_http_file_cache_set_header(r, u->buffer.start) != NGX_OK) {