From: Rafael Zalamena <rzalamena@opensourcerouting.org>
Date: Tue, 15 Jan 2019 22:23:06 +0000 (-0200)
Subject: bfdd: refactor state change handler
X-Git-Tag: 7.1_pulled~230^2~18
X-Git-Url: https://git.puffer.fish/?a=commitdiff_plain;h=aef131afc5fd722b34c4503e35753283530dfdc8;p=matthieu%2Ffrr.git

bfdd: refactor state change handler

Expand state change handling into smaller functions with more
explanatory commentaries. This also handles some corner cases that
were not being handled.

Signed-off-by: Rafael Zalamena <rzalamena@opensourcerouting.org>
---

diff --git a/bfdd/bfd.c b/bfdd/bfd.c
index df263a91c9..235f9c06a8 100644
--- a/bfdd/bfd.c
+++ b/bfdd/bfd.c
@@ -694,6 +694,129 @@ void bfd_set_polling(struct bfd_session *bs)
 	bs->polling = 1;
 }
 
+/*
+ * bs_<state>_handler() functions implement the BFD state machine
+ * transition mechanism. `<state>` is the current session state and
+ * the parameter `nstate` is the peer new state.
+ */
+void bs_admin_down_handler(struct bfd_session *bs, int nstate);
+void bs_down_handler(struct bfd_session *bs, int nstate);
+void bs_init_handler(struct bfd_session *bs, int nstate);
+void bs_up_handler(struct bfd_session *bs, int nstate);
+
+void bs_admin_down_handler(struct bfd_session *bs __attribute__((__unused__)),
+			   int nstate __attribute__((__unused__)))
+{
+	/*
+	 * We are administratively down, there is no state machine
+	 * handling.
+	 */
+}
+
+void bs_down_handler(struct bfd_session *bs, int nstate)
+{
+	switch (nstate) {
+	case PTM_BFD_ADM_DOWN:
+		/*
+		 * Remote peer doesn't want to talk, so lets keep the
+		 * connection down.
+		 */
+	case PTM_BFD_UP:
+		/* Peer can't be up yet, wait it go to 'init' or 'down'. */
+		break;
+
+	case PTM_BFD_DOWN:
+		/*
+		 * Remote peer agreed that the path is down, lets try to
+		 * bring it up.
+		 */
+		bs->ses_state = PTM_BFD_INIT;
+		break;
+
+	case PTM_BFD_INIT:
+		/*
+		 * Remote peer told us his path is up, lets turn
+		 * activate the session.
+		 */
+		ptm_bfd_ses_up(bs);
+		break;
+
+	default:
+		log_debug("state-change: unhandled neighbor state: %d", nstate);
+		break;
+	}
+}
+
+void bs_init_handler(struct bfd_session *bs, int nstate)
+{
+	switch (nstate) {
+	case PTM_BFD_ADM_DOWN:
+		/*
+		 * Remote peer doesn't want to talk, so lets make the
+		 * connection down.
+		 */
+		bs->ses_state = PTM_BFD_DOWN;
+		break;
+
+	case PTM_BFD_DOWN:
+		/* Remote peer hasn't moved to first stage yet. */
+		break;
+
+	case PTM_BFD_INIT:
+	case PTM_BFD_UP:
+		/* We agreed on the settings and the path is up. */
+		ptm_bfd_ses_up(bs);
+		break;
+
+	default:
+		log_debug("state-change: unhandled neighbor state: %d", nstate);
+		break;
+	}
+}
+
+void bs_up_handler(struct bfd_session *bs, int nstate)
+{
+	switch (nstate) {
+	case PTM_BFD_ADM_DOWN:
+	case PTM_BFD_DOWN:
+		/* Peer lost or asked to shutdown connection. */
+		ptm_bfd_ses_dn(bs, BD_NEIGHBOR_DOWN);
+		break;
+
+	case PTM_BFD_INIT:
+	case PTM_BFD_UP:
+		/* Path is up and working. */
+		break;
+
+	default:
+		log_debug("state-change: unhandled neighbor state: %d", nstate);
+		break;
+	}
+}
+
+void bs_state_handler(struct bfd_session *bs, int nstate)
+{
+	switch (bs->ses_state) {
+	case PTM_BFD_ADM_DOWN:
+		bs_admin_down_handler(bs, nstate);
+		break;
+	case PTM_BFD_DOWN:
+		bs_down_handler(bs, nstate);
+		break;
+	case PTM_BFD_INIT:
+		bs_init_handler(bs, nstate);
+		break;
+	case PTM_BFD_UP:
+		bs_up_handler(bs, nstate);
+		break;
+
+	default:
+		log_debug("state-change: [%s] is in invalid state: %d",
+			  bs_to_string(bs), nstate);
+		break;
+	}
+}
+
 
 /*
  * Helper functions.
diff --git a/bfdd/bfd.h b/bfdd/bfd.h
index a3e5ad1447..dccc3dfcc6 100644
--- a/bfdd/bfd.h
+++ b/bfdd/bfd.h
@@ -525,6 +525,7 @@ struct bfd_session *ptm_bfd_sess_find(struct bfd_pkt *cp, char *port_name,
 struct bfd_session *bs_peer_find(struct bfd_peer_cfg *bpc);
 int bfd_session_update_label(struct bfd_session *bs, const char *nlabel);
 void bfd_set_polling(struct bfd_session *bs);
+void bs_state_handler(struct bfd_session *, int);
 const char *satostr(struct sockaddr_any *sa);
 const char *diag2str(uint8_t diag);
 int strtosa(const char *addr, struct sockaddr_any *sa);
diff --git a/bfdd/bfd_packet.c b/bfdd/bfd_packet.c
index 9cfd7e866f..ef97e34623 100644
--- a/bfdd/bfd_packet.c
+++ b/bfdd/bfd_packet.c
@@ -668,29 +668,8 @@ int bfd_recv_cb(struct thread *t)
 	/* Save remote diagnostics before state switch. */
 	bfd->remote_diag = cp->diag & BFD_DIAGMASK;
 
-	/* State switch from section 6.8.6 */
-	if (BFD_GETSTATE(cp->flags) == PTM_BFD_ADM_DOWN) {
-		if (bfd->ses_state != PTM_BFD_DOWN)
-			ptm_bfd_ses_dn(bfd, BD_NEIGHBOR_DOWN);
-	} else {
-		switch (bfd->ses_state) {
-		case (PTM_BFD_DOWN):
-			if (BFD_GETSTATE(cp->flags) == PTM_BFD_INIT)
-				ptm_bfd_ses_up(bfd);
-			else if (BFD_GETSTATE(cp->flags) == PTM_BFD_DOWN)
-				bfd->ses_state = PTM_BFD_INIT;
-			break;
-		case (PTM_BFD_INIT):
-			if (BFD_GETSTATE(cp->flags) == PTM_BFD_INIT
-			    || BFD_GETSTATE(cp->flags) == PTM_BFD_UP)
-				ptm_bfd_ses_up(bfd);
-			break;
-		case (PTM_BFD_UP):
-			if (BFD_GETSTATE(cp->flags) == PTM_BFD_DOWN)
-				ptm_bfd_ses_dn(bfd, BD_NEIGHBOR_DOWN);
-			break;
-		}
-	}
+	/* State switch from section 6.2. */
+	bs_state_handler(bfd, BFD_GETSTATE(cp->flags));
 
 	/*
 	 * Handle echo packet status: