Ignore an "Accept" HTTP header value

We were too strict regarding the value and presence of "Accept" HTTP
header, slightly breaking compatibility with the specification.

According to RFC8484 client SHOULD add "Accept" header to the requests
but MUST be able to handle "application/dns-message" media type
regardless of the value of the header. That basically suggests we
ignore its value.

Besides, verifying the value of the "Accept" header is a bit tricky
because it could contain multiple media types, thus requiring proper
parsing. That is doable but does not provide us with any benefits.

Among other things, not verifying the value also fixes compatibility
with clients, which could advertise multiple media types as supported,
which we should accept. For example, it is possible for a perfectly
valid request to contain "application/dns-message", "application/*",
and "*/*" in the "Accept" header value. Still, we would treat such a
request as invalid.

diff --git a/lib/isc/netmgr/http.c b/lib/isc/netmgr/http.c
index fe9f73bd70e143b115fd5d8023b25737358e4ebb..723dd57e7e8e3b7615bf08100dc68b4a007df54b 100644 (file)
--- a/lib/isc/netmgr/http.c
+++ b/lib/isc/netmgr/http.c
@@ -1805,23 +1805,6 @@ server_handle_content_type_header(isc_nmsocket_t *socket, const uint8_t *value,
        return (resp);
 }
 
-static isc_http_error_responses_t
-server_handle_accept_header(isc_nmsocket_t *socket, const uint8_t *value,
-                           const size_t valuelen) {
-       const char type_accept_all[] = "*/*";
-       const char type_dns_message[] = DNS_MEDIA_TYPE;
-       isc_http_error_responses_t resp = ISC_HTTP_ERROR_SUCCESS;
-
-       UNUSED(socket);
-
-       if (!(HEADER_MATCH(type_dns_message, value, valuelen) ||
-             HEADER_MATCH(type_accept_all, value, valuelen)))
-       {
-               resp = ISC_HTTP_ERROR_UNSUPPORTED_MEDIA_TYPE;
-       }
-       return (resp);
-}
-
 static isc_http_error_responses_t
 server_handle_header(isc_nmsocket_t *socket, const uint8_t *name,
                     size_t namelen, const uint8_t *value,
@@ -1831,7 +1814,6 @@ server_handle_header(isc_nmsocket_t *socket, const uint8_t *name,
        const char path[] = ":path";
        const char method[] = ":method";
        const char scheme[] = ":scheme";
-       const char accept[] = "accept";
        const char content_length[] = "Content-Length";
        const char content_type[] = "Content-Type";
 
@@ -1852,9 +1834,6 @@ server_handle_header(isc_nmsocket_t *socket, const uint8_t *name,
        } else if (!was_error && HEADER_MATCH(content_type, name, namelen)) {
                code = server_handle_content_type_header(socket, value,
                                                         valuelen);
-       } else if (!was_error &&
-                  HEADER_MATCH(accept, (const char *)name, namelen)) {
-               code = server_handle_accept_header(socket, value, valuelen);
        }
 
        return (code);