Disable srvdst events asap when xferring to child and in split mode

This is the correct implementation. And disabling later on is
problematic while terminating, and can even cause a crash.

src/protopassthrough.c

@@ -84,16 +84,6 @@ protopassthrough_engage(pxy_conn_ctx_t *ctx)
 	// If srvdst has been xferred to the first child conn, the child should free it, not the parent
 	if (ctx->divert && !ctx->srvdst_xferred) {
 		ctx->srvdst.free(ctx->srvdst.bev, ctx);
-	} else /*if (!ctx->divert || ctx->srvdst_xferred)*/ {
-		struct bufferevent *ubev = bufferevent_get_underlying(ctx->srvdst.bev);
-
-		bufferevent_setcb(ctx->srvdst.bev, NULL, NULL, NULL, NULL);
-		bufferevent_disable(ctx->srvdst.bev, EV_READ|EV_WRITE);
-
-		if (ubev) {
-			bufferevent_setcb(ubev, NULL, NULL, NULL, NULL);
-			bufferevent_disable(ubev, EV_READ|EV_WRITE);
-		}
 	}
 	ctx->srvdst.bev = NULL;
 	ctx->srvdst.ssl = NULL;

src/protossl.c

@@ -1533,6 +1533,10 @@ protossl_setup_dst_child(pxy_conn_child_ctx_t *ctx)
 		ctx->conn->srvdst_xferred = 1;
 		ctx->srvdst_xferred = 1;
 		ctx->dst = ctx->conn->srvdst;
+
+		// See the comments in prototcp_setup_dst()
+		prototcp_disable_events_srvdst(ctx->conn);
+
 		bufferevent_setcb(ctx->dst.bev, pxy_bev_readcb_child, pxy_bev_writecb_child, pxy_bev_eventcb_child, ctx);
 		ctx->protoctx->bev_eventcb(ctx->dst.bev, BEV_EVENT_CONNECTED, ctx);
 	} else {

src/prototcp.c

@@ -111,6 +111,19 @@ prototcp_setup_src(pxy_conn_ctx_t *ctx)
 	return 0;
 }
 
+void
+prototcp_disable_events_srvdst(pxy_conn_ctx_t *ctx)
+{
+	bufferevent_setcb(ctx->srvdst.bev, NULL, NULL, NULL, NULL);
+	bufferevent_disable(ctx->srvdst.bev, EV_READ|EV_WRITE);
+
+	struct bufferevent *ubev = bufferevent_get_underlying(ctx->srvdst.bev);
+	if (ubev) {
+		bufferevent_setcb(ubev, NULL, NULL, NULL, NULL);
+		bufferevent_disable(ubev, EV_READ|EV_WRITE);
+	}
+}
+
 int
 prototcp_setup_dst(pxy_conn_ctx_t *ctx)
 {
@@ -131,17 +144,12 @@ prototcp_setup_dst(pxy_conn_ctx_t *ctx)
 		// But if we don't NULL the callbacks of srvdst in split mode,
 		// we randomly but rarely get a second eof event for srvdst during conn termination (especially on arm64),
 		// which crashes us with signal 11 or 10, because the first eof event for dst frees the ctx.
+		// This does not seem to happen with srvdst_xferred, but just to be safe we do the same for it too.
 		// Note that we don't free anything here, but just disable callbacks and events.
 		// This seems to be an issue with libevent.
 		// @todo Why does libevent raise the same event again for an already disabled and freed conn end?
 		// Note again that srvdst == dst or child_dst here.
-		bufferevent_setcb(ctx->srvdst.bev, NULL, NULL, NULL, NULL);
-		bufferevent_disable(ctx->srvdst.bev, EV_READ|EV_WRITE);
-		struct bufferevent *ubev = bufferevent_get_underlying(ctx->srvdst.bev);
-		if (ubev) {
-			bufferevent_setcb(ubev, NULL, NULL, NULL, NULL);
-			bufferevent_disable(ubev, EV_READ|EV_WRITE);
-		}
+		prototcp_disable_events_srvdst(ctx);
 
 		bufferevent_setcb(ctx->dst.bev, pxy_bev_readcb, pxy_bev_writecb, pxy_bev_eventcb, ctx);
 		ctx->protoctx->bev_eventcb(ctx->dst.bev, BEV_EVENT_CONNECTED, ctx);
@@ -200,6 +208,10 @@ prototcp_setup_dst_child(pxy_conn_child_ctx_t *ctx)
 		ctx->conn->srvdst_xferred = 1;
 		ctx->srvdst_xferred = 1;
 		ctx->dst = ctx->conn->srvdst;
+
+		// See the comments in prototcp_setup_dst()
+		prototcp_disable_events_srvdst(ctx->conn);
+
 		bufferevent_setcb(ctx->dst.bev, pxy_bev_readcb_child, pxy_bev_writecb_child, pxy_bev_eventcb_child, ctx);
 		ctx->protoctx->bev_eventcb(ctx->dst.bev, BEV_EVENT_CONNECTED, ctx);
 	} else {

src/prototcp.h

@@ -82,6 +82,7 @@ int prototcp_enable_src(pxy_conn_ctx_t *) NONNULL(1);
 void prototcp_bev_eventcb_srvdst(struct bufferevent *, short, pxy_conn_ctx_t *) NONNULL(1);
 
 int prototcp_setup_src(pxy_conn_ctx_t *) NONNULL(1);
+void prototcp_disable_events_srvdst(pxy_conn_ctx_t *) NONNULL(1);
 int prototcp_setup_dst(pxy_conn_ctx_t *) NONNULL(1);
 int prototcp_setup_srvdst(pxy_conn_ctx_t *) NONNULL(1);
 

src/pxyconn.c

@@ -416,20 +416,7 @@ pxy_conn_free(pxy_conn_ctx_t *ctx, int by_requestor)
 		// If srvdst has been xferred to the first child conn, the child should free it, not the parent
 		if (ctx->divert && !ctx->srvdst_xferred) {
 			ctx->srvdst.free(ctx->srvdst.bev, ctx);
-		} else if (ctx->srvdst_xferred) {
-			// @see prototcp_setup_dst()
-			// It does not seem to happen with srvdst_xferred, but just to be safe we do the same for it too.
-			struct bufferevent *ubev = bufferevent_get_underlying(ctx->srvdst.bev);
-
-			bufferevent_setcb(ctx->srvdst.bev, NULL, NULL, NULL, NULL);
-			bufferevent_disable(ctx->srvdst.bev, EV_READ|EV_WRITE);
-
-			if (ubev) {
-				bufferevent_setcb(ubev, NULL, NULL, NULL, NULL);
-				bufferevent_disable(ubev, EV_READ|EV_WRITE);
-			}
 		}
-		// else if (!ctx->divert) {}
 		ctx->srvdst.bev = NULL;
 	}