ext/max_record: server shouldn't send it with record_size_limit

Otherwise, the connection will be disconnected by the client, as
suggested in RFC: A client MUST treat receipt of both
"max_fragment_length" and "record_size_limit" as a fatal error, and it
SHOULD generate an "illegal_parameter" alert.

Signed-off-by: Daiki Ueno <dueno@redhat.com>

4 files changed, 11 insertions, 8 deletions

diff --git a/lib/ext/max_record.c b/lib/ext/max_record.c
index 2a7a9d3496..17c06e483f 100644
--- a/lib/ext/max_record.c
+++ b/lib/ext/max_record.c
@@ -153,16 +153,16 @@ _gnutls_max_record_send_params(gnutls_session_t session,
 
 	} else {		/* server side */
 
+		if (session->internals.hsk_flags & HSK_RECORD_SIZE_LIMIT_SENT)
+			return 0;
+
 		if (session->security_parameters.max_record_recv_size !=
 		    DEFAULT_MAX_RECORD_SIZE) {
 			ret = _gnutls_mre_record2num
 			      (session->security_parameters.
 			       max_record_recv_size);
-
-			/* it's not an error, as long as we send the
-			 * record_size_limit extension with that value */
 			if (ret < 0)
-				return 0;
+				return gnutls_assert_val(ret);
 
 			p = (uint8_t) ret;
 			ret = _gnutls_buffer_append_data(extdata, &p, 1);
diff --git a/lib/ext/record_size_limit.c b/lib/ext/record_size_limit.c
index c74ae81e4b..607ecdb76f 100644
--- a/lib/ext/record_size_limit.c
+++ b/lib/ext/record_size_limit.c
@@ -96,5 +96,7 @@ _gnutls_record_size_limit_send_params(gnutls_session_t session,
 	if (ret < 0)
 		return gnutls_assert_val(ret);
 
+	session->internals.hsk_flags |= HSK_RECORD_SIZE_LIMIT_SENT;
+
 	return 2;
 }
diff --git a/lib/gnutls_int.h b/lib/gnutls_int.h
index 93ffd7cee9..f99e40a171 100644
--- a/lib/gnutls_int.h
+++ b/lib/gnutls_int.h
@@ -325,8 +325,7 @@ typedef enum recv_state_t {
 /* IDs are allocated in a way that all values fit in 64-bit integer as (1<<val) */
 typedef enum extensions_t {
 	GNUTLS_EXTENSION_INVALID = 0xffff,
-	GNUTLS_EXTENSION_MAX_RECORD_SIZE = 0,
-	GNUTLS_EXTENSION_STATUS_REQUEST,
+	GNUTLS_EXTENSION_STATUS_REQUEST = 0,
 	GNUTLS_EXTENSION_CERT_TYPE,
 	GNUTLS_EXTENSION_CLIENT_CERT_TYPE,
 	GNUTLS_EXTENSION_SERVER_CERT_TYPE,
@@ -349,6 +348,7 @@ typedef enum extensions_t {
 	GNUTLS_EXTENSION_EARLY_DATA,
 	GNUTLS_EXTENSION_PSK_KE_MODES,
 	GNUTLS_EXTENSION_RECORD_SIZE_LIMIT,
+	GNUTLS_EXTENSION_MAX_RECORD_SIZE,
 	/*
 	 * pre_shared_key and dumbfw must always be the last extensions,
 	 * in that order */
@@ -1357,6 +1357,7 @@ typedef struct {
 					 * server: intend to process early data
 					 */
 #define HSK_RECORD_SIZE_LIMIT_NEGOTIATED (1<<24)
+#define HSK_RECORD_SIZE_LIMIT_SENT (1<<25) /* record_size_limit extension was sent */
 
 	/* The hsk_flags are for use within the ongoing handshake;
 	 * they are reset to zero prior to handshake start by gnutls_handshake. */
diff --git a/lib/hello_ext.c b/lib/hello_ext.c
index 5692a14d2d..2d7cd806f6 100644
--- a/lib/hello_ext.c
+++ b/lib/hello_ext.c
@@ -64,7 +64,6 @@ unset_ext_data(gnutls_session_t session, const struct hello_ext_entry_st *, unsi
 static void unset_resumed_ext_data(gnutls_session_t session, const struct hello_ext_entry_st *, unsigned idx);
 
 static hello_ext_entry_st const *extfunc[MAX_EXT_TYPES+1] = {
-	[GNUTLS_EXTENSION_MAX_RECORD_SIZE] = &ext_mod_max_record_size,
 	[GNUTLS_EXTENSION_EXT_MASTER_SECRET] = &ext_mod_ext_master_secret,
 	[GNUTLS_EXTENSION_SUPPORTED_VERSIONS] = &ext_mod_supported_versions,
 	[GNUTLS_EXTENSION_POST_HANDSHAKE] = &ext_mod_post_handshake,
@@ -95,9 +94,10 @@ static hello_ext_entry_st const *extfunc[MAX_EXT_TYPES+1] = {
 #ifdef ENABLE_ALPN
 	[GNUTLS_EXTENSION_ALPN] = &ext_mod_alpn,
 #endif
+	[GNUTLS_EXTENSION_RECORD_SIZE_LIMIT] = &ext_mod_record_size_limit,
+	[GNUTLS_EXTENSION_MAX_RECORD_SIZE] = &ext_mod_max_record_size,
 	[GNUTLS_EXTENSION_PSK_KE_MODES] = &ext_mod_psk_ke_modes,
 	[GNUTLS_EXTENSION_PRE_SHARED_KEY] = &ext_mod_pre_shared_key,
-	[GNUTLS_EXTENSION_RECORD_SIZE_LIMIT] = &ext_mod_record_size_limit,
 	/* This must be the last extension registered.
 	 */
 	[GNUTLS_EXTENSION_DUMBFW] = &ext_mod_dumbfw,