MINOR: http: adjust the list of supposedly cacheable methods
We used to have a rule inherited from RFC2616 saying that the POST
method was the only uncacheable one, but things have changed since
and RFC7231+7234 made it clear that in fact only GET/HEAD/OPTIONS/TRACE
are cacheable. Currently this rule is only used to detect cacheable
cookies.
diff --git a/doc/configuration.txt b/doc/configuration.txt
index 87fc567..a4b3652 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -5440,8 +5440,9 @@
- all those without "Set-Cookie" header ;
- all those with a return code other than 200, 203, 206, 300, 301, 410,
provided that the server has not set a "Cache-control: public" header ;
- - all those that come from a POST request, provided that the server has not
- set a 'Cache-Control: public' header ;
+ - all those that result from a request using a method other than GET, HEAD,
+ OPTIONS, TRACE, provided that the server has not set a 'Cache-Control:
+ public' header field ;
- those with a 'Pragma: no-cache' header
- those with a 'Cache-control: private' header
- those with a 'Cache-control: no-store' header
diff --git a/src/proto_http.c b/src/proto_http.c
index c226d37..ebc72c9 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -5398,12 +5398,23 @@
* by a cache (...) unless a cache-control
* directive prohibits caching."
*
- * RFC2616 @9.5: POST method :
- * "Responses to this method are not cacheable,
- * unless the response includes appropriate
- * Cache-Control or Expires header fields."
+ * RFC7234#4:
+ * A cache MUST write through requests with methods
+ * that are unsafe (Section 4.2.1 of [RFC7231]) to
+ * the origin server; i.e., a cache is not allowed
+ * to generate a reply to such a request before
+ * having forwarded the request and having received
+ * a corresponding response.
+ *
+ * RFC7231#4.2.1:
+ * Of the request methods defined by this
+ * specification, the GET, HEAD, OPTIONS, and TRACE
+ * methods are defined to be safe.
*/
- if (likely(txn->meth != HTTP_METH_POST) &&
+ if (likely(txn->meth == HTTP_METH_GET ||
+ txn->meth == HTTP_METH_HEAD ||
+ txn->meth == HTTP_METH_OPTIONS ||
+ txn->meth == HTTP_METH_TRACE) &&
((s->be->options & PR_O_CHK_CACHE) || (s->be->ck_opts & PR_CK_NOC)))
txn->flags |= TX_CACHEABLE | TX_CACHE_COOK;
break;