MINOR: mux: add flags to describe a mux's capabilities

This new field will be used to describe certain properties of some
muxes. For now we only add MX_FL_CLEAN_ABRT to indicate that a mux
is able to unambiguously report aborts using CS_FL_ERROR contrary
to others who may only report it via a read0. This will be used to
improve handling of the abortonclose option with H2. Other flags
may come later to report multiplexing capabilities or not, support
of client/server sides etc.

include/types/connection.h

@@ -255,6 +255,12 @@ enum {
 	XPRT_ENTRIES /* must be last one */
 };
 
+/* MUX-specific flags */
+enum {
+	MX_FL_NONE        = 0x00000000,
+	MX_FL_CLEAN_ABRT  = 0x00000001, /* abort is clearly reported as an error */
+};
+
 /* xprt_ops describes transport-layer operations for a connection. They
  * generally run over a socket-based control layer, but not always. Some
  * of them are used for data transfer with the upper layer (rcv_*, snd_*)
@@ -299,6 +305,7 @@ struct mux_ops {
 
 	struct conn_stream *(*attach)(struct connection *); /* Create and attach a conn_stream to an outgoing connection */
 	void (*detach)(struct conn_stream *); /* Detach a conn_stream from an outgoing connection, when the request is done */
+	unsigned int flags;                           /* some flags characterizing the mux's capabilities (MX_FL_*) */
 	char name[8];                                 /* mux layer name, zero-terminated */
 };
 

src/mux_h2.c

@@ -3330,6 +3330,7 @@ const struct mux_ops h2_ops = {
 	.detach = h2_detach,
 	.shutr = h2_shutr,
 	.shutw = h2_shutw,
+	.flags = MX_FL_CLEAN_ABRT,
 	.name = "H2",
 };
 

src/mux_pt.c

@@ -214,6 +214,7 @@ const struct mux_ops mux_pt_ops = {
 	.detach = mux_pt_detach,
 	.shutr = mux_pt_shutr,
 	.shutw = mux_pt_shutw,
+	.flags = MX_FL_NONE,
 	.name = "PASS",
 };