MINOR: cli: give the show_fd helpers the ability to report a suspicious entry

Now the show_fd helpers at the transport and mux levels return an integer
which indicates whether or not the inspected entry looks suspicious. When
an entry is reported as suspicious, "show fd" will suffix it with an
exclamation mark ('!') in the dump, that is supposed to help detecting
them.

For now, helpers were adjusted to adapt to the new API but none of them
reports any suspicious entry yet.

doc/management.txt

@@ -2126,7 +2126,10 @@ show fd [<fd>]
   listener's state and its frontend are reported. There is no point in using
   this command without a good knowledge of the internals. It's worth noting
   that the output format may evolve over time so this output must not be parsed
-  by tools designed to be durable.
+  by tools designed to be durable. Some internal structure states may look
+  suspicious to the function listing them, in this case the output line will be
+  suffixed with an exclamation mark ('!'). This may help find a starting point
+  when trying to diagnose an incident.
 
 show info [typed|json] [desc]
   Dump info about haproxy status on current process. If "typed" is passed as an

include/haproxy/connection-t.h

@@ -381,7 +381,7 @@ struct xprt_ops {
 	int (*unsubscribe)(struct connection *conn, void *xprt_ctx, int event_type, struct wait_event *es); /* Unsubscribe <es> from events */
 	int (*remove_xprt)(struct connection *conn, void *xprt_ctx, void *toremove_ctx, const struct xprt_ops *newops, void *newctx); /* Remove an xprt from the connection, used by temporary xprt such as the handshake one */
 	int (*add_xprt)(struct connection *conn, void *xprt_ctx, void *toadd_ctx, const struct xprt_ops *toadd_ops, void **oldxprt_ctx, const struct xprt_ops **oldxprt_ops); /* Add a new XPRT as the new xprt, and return the old one */
-	void (*show_fd)(struct buffer *, const struct connection *, const void *ctx); /* append some data about xprt for "show fd" */
+	int (*show_fd)(struct buffer *, const struct connection *, const void *ctx); /* append some data about xprt for "show fd"; returns non-zero if suspicious */
 };
 
 /* mux_ops describes the mux operations, which are to be performed at the
@@ -404,7 +404,7 @@ struct mux_ops {
 	struct conn_stream *(*attach)(struct connection *, struct session *sess); /* Create and attach a conn_stream to an outgoing connection */
 	const struct conn_stream *(*get_first_cs)(const struct connection *); /* retrieves any valid conn_stream from this connection */
 	void (*detach)(struct conn_stream *); /* Detach a conn_stream from an outgoing connection, when the request is done */
-	void (*show_fd)(struct buffer *, struct connection *); /* append some data about connection into chunk for "show fd" */
+	int (*show_fd)(struct buffer *, struct connection *); /* append some data about connection into chunk for "show fd"; returns non-zero if suspicious */
 	int (*subscribe)(struct conn_stream *cs, int event_type,  struct wait_event *es); /* Subscribe <es> to events, such as "being able to send" */
 	int (*unsubscribe)(struct conn_stream *cs, int event_type,  struct wait_event *es); /* Unsubscribe <es> from events */
 	int (*avail_streams)(struct connection *conn); /* Returns the number of streams still available for a connection */

src/cli.c

@@ -1037,6 +1037,7 @@ static int cli_io_handler_show_fd(struct appctx *appctx)
 		const void *xprt_ctx = NULL;
 		uint32_t conn_flags = 0;
 		int is_back = 0;
+		int suspicious = 0;
 
 		fdt = fdtab[fd];
 
@@ -1100,7 +1101,7 @@ static int cli_io_handler_show_fd(struct appctx *appctx)
 			if (mux) {
 				chunk_appendf(&trash, " mux=%s ctx=%p", mux->name, ctx);
 				if (mux->show_fd)
-					mux->show_fd(&trash, fdt.owner);
+					suspicious |= mux->show_fd(&trash, fdt.owner);
 			}
 			else
 				chunk_appendf(&trash, " nomux");
@@ -1110,7 +1111,7 @@ static int cli_io_handler_show_fd(struct appctx *appctx)
 				if (xprt_ctx || xprt->show_fd)
 					chunk_appendf(&trash, " xprt_ctx=%p", xprt_ctx);
 				if (xprt->show_fd)
-					xprt->show_fd(&trash, conn, xprt_ctx);
+					suspicious |= xprt->show_fd(&trash, conn, xprt_ctx);
 			}
 		}
 		else if (fdt.iocb == sock_accept_iocb) {
@@ -1124,7 +1125,7 @@ static int cli_io_handler_show_fd(struct appctx *appctx)
 #ifdef DEBUG_FD
 		chunk_appendf(&trash, " evcnt=%u", fdtab[fd].event_count);
 #endif
-		chunk_appendf(&trash, "\n");
+		chunk_appendf(&trash, "%s\n", suspicious ? " !" : "");
 
 		if (ci_putchk(si_ic(si), &trash) == -1) {
 			si_rx_room_blk(si);

src/mux_fcgi.c

@@ -4053,7 +4053,7 @@ static size_t fcgi_snd_buf(struct conn_stream *cs, struct buffer *buf, size_t co
 }
 
 /* for debugging with CLI's "show fd" command */
-static void fcgi_show_fd(struct buffer *msg, struct connection *conn)
+static int fcgi_show_fd(struct buffer *msg, struct connection *conn)
 {
 	struct fcgi_conn *fconn = conn->ctx;
 	struct fcgi_strm *fstrm = NULL;
@@ -4064,7 +4064,7 @@ static void fcgi_show_fd(struct buffer *msg, struct connection *conn)
 	struct buffer *hmbuf, *tmbuf;
 
 	if (!fconn)
-		return;
+		return 0;
 
 	list_for_each_entry(fstrm, &fconn->send_list, send_list)
 		send_cnt++;
@@ -4116,6 +4116,7 @@ static void fcgi_show_fd(struct buffer *msg, struct connection *conn)
 			}
 		}
 	}
+	return 0;
 }
 
 /* Migrate the the connection to the current thread.

src/mux_h1.c

@@ -3141,7 +3141,7 @@ static int h1_ctl(struct connection *conn, enum mux_ctl_type mux_ctl, void *outp
 }
 
 /* for debugging with CLI's "show fd" command */
-static void h1_show_fd(struct buffer *msg, struct connection *conn)
+static int h1_show_fd(struct buffer *msg, struct connection *conn)
 {
 	struct h1c *h1c = conn->ctx;
 	struct h1s *h1s = h1c->h1s;
@@ -3181,6 +3181,7 @@ static void h1_show_fd(struct buffer *msg, struct connection *conn)
 			}
 		}
 	}
+	return 0;
 }
 
 

src/mux_h2.c

@@ -6192,7 +6192,7 @@ static size_t h2_snd_buf(struct conn_stream *cs, struct buffer *buf, size_t coun
 }
 
 /* for debugging with CLI's "show fd" command */
-static void h2_show_fd(struct buffer *msg, struct connection *conn)
+static int h2_show_fd(struct buffer *msg, struct connection *conn)
 {
 	struct h2c *h2c = conn->ctx;
 	struct h2s *h2s = NULL;
@@ -6204,7 +6204,7 @@ static void h2_show_fd(struct buffer *msg, struct connection *conn)
 	struct buffer *hmbuf, *tmbuf;
 
 	if (!h2c)
-		return;
+		return 0;
 
 	list_for_each_entry(h2s, &h2c->fctl_list, list)
 		fctl_cnt++;
@@ -6262,6 +6262,7 @@ static void h2_show_fd(struct buffer *msg, struct connection *conn)
 			}
 		}
 	}
+	return 0;
 }
 
 /* Migrate the the connection to the current thread.

src/ssl_sock.c

@@ -6354,12 +6354,12 @@ static int ssl_check_async_engine_count(void) {
 /* "show fd" helper to dump ssl internals. Warning: the output buffer is often
  * the common trash!
  */
-static void ssl_sock_show_fd(struct buffer *buf, const struct connection *conn, const void *ctx)
+static int ssl_sock_show_fd(struct buffer *buf, const struct connection *conn, const void *ctx)
 {
 	const struct ssl_sock_ctx *sctx = ctx;
 
 	if (!sctx)
-		return;
+		return 0;
 
 	if (sctx->conn != conn)
 		chunk_appendf(&trash, " xctx.conn=%p(BOGUS!)", sctx->conn);
@@ -6383,6 +6383,7 @@ static void ssl_sock_show_fd(struct buffer *buf, const struct connection *conn,
 	}
 	chunk_appendf(&trash, " .sent_early=%d", sctx->sent_early_data);
 	chunk_appendf(&trash, " .early_in=%d", (int)sctx->early_buf.data);
+	return 0;
 }
 
 #if (defined SSL_CTRL_SET_TLSEXT_TICKET_KEY_CB && TLS_TICKETS_NO > 0)