p2p_tc: Implement a peer to peer transparent clock.

The P2P TC forwards Announce, Management, Signaling, and Sync
messages, consumes P2P Delay messages, and drops E2E Delay messages.

This implementation tracks the GM using the BMCA in order
to syntonize (or possibly even synchronize) with it.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>

clock.c

@@ -874,9 +874,9 @@ struct clock *clock_create(enum clock_type type, struct config *config,
 	switch (type) {
 	case CLOCK_TYPE_ORDINARY:
 	case CLOCK_TYPE_BOUNDARY:
+	case CLOCK_TYPE_P2P:
 		c->type = type;
 		break;
-	case CLOCK_TYPE_P2P:
 	case CLOCK_TYPE_E2E:
 	case CLOCK_TYPE_MANAGEMENT:
 		return NULL;

makefile

@@ -25,8 +25,8 @@ LDLIBS	= -lm -lrt $(EXTRA_LDFLAGS)
 PRG	= ptp4l hwstamp_ctl nsm phc2sys phc_ctl pmc timemaster
 OBJ     = bmc.o clock.o clockadj.o clockcheck.o config.o fault.o \
  filter.o fsm.o hash.o linreg.o mave.o mmedian.o msg.o ntpshm.o nullf.o phc.o \
- pi.o port.o print.o ptp4l.o raw.o rtnl.o servo.o sk.o stats.o tc.o telecom.o \
+ pi.o port.o print.o ptp4l.o p2p_tc.o raw.o rtnl.o servo.o sk.o stats.o tc.o \
- tlv.o transport.o tsproc.o udp.o udp6.o uds.o util.o version.o
+ telecom.o tlv.o transport.o tsproc.o udp.o udp6.o uds.o util.o version.o
 
 OBJECTS	= $(OBJ) hwstamp_ctl.o nsm.o phc2sys.o phc_ctl.o pmc.o pmc_common.o \
  sysoff.o timemaster.o

p2p_tc.c

@@ -0,0 +1,229 @@
+/**
+ * @file p2p_tc.c
+ * @note Copyright (C) 2018 Richard Cochran <richardcochran@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA.
+ */
+#include <errno.h>
+
+#include "port.h"
+#include "port_private.h"
+#include "print.h"
+#include "rtnl.h"
+#include "tc.h"
+
+static int p2p_delay_request(struct port *p)
+{
+	switch (p->state) {
+	case PS_INITIALIZING:
+	case PS_FAULTY:
+	case PS_DISABLED:
+		return 0;
+	case PS_LISTENING:
+	case PS_PRE_MASTER:
+	case PS_MASTER:
+	case PS_PASSIVE:
+	case PS_UNCALIBRATED:
+	case PS_SLAVE:
+	case PS_GRAND_MASTER:
+		break;
+	}
+	return port_delay_request(p);
+}
+
+void p2p_dispatch(struct port *p, enum fsm_event event, int mdiff)
+{
+	if (!port_state_update(p, event, mdiff)) {
+		return;
+	}
+	if (!portnum(p)) {
+		/* UDS needs no timers. */
+		return;
+	}
+
+	port_clr_tmo(p->fda.fd[FD_ANNOUNCE_TIMER]);
+	port_clr_tmo(p->fda.fd[FD_SYNC_RX_TIMER]);
+	/* Leave FD_DELAY_TIMER running. */
+	port_clr_tmo(p->fda.fd[FD_QUALIFICATION_TIMER]);
+	port_clr_tmo(p->fda.fd[FD_MANNO_TIMER]);
+	port_clr_tmo(p->fda.fd[FD_SYNC_TX_TIMER]);
+
+	/*
+	 * Handle the side effects of the state transition.
+	 */
+	switch (p->state) {
+	case PS_INITIALIZING:
+		break;
+	case PS_FAULTY:
+	case PS_DISABLED:
+		port_disable(p);
+		break;
+	case PS_LISTENING:
+		port_set_announce_tmo(p);
+		port_set_delay_tmo(p);
+		break;
+	case PS_PRE_MASTER:
+		port_set_qualification_tmo(p);
+		break;
+	case PS_MASTER:
+	case PS_GRAND_MASTER:
+		break;
+	case PS_PASSIVE:
+		port_set_announce_tmo(p);
+		break;
+	case PS_UNCALIBRATED:
+	case PS_SLAVE:
+		port_set_announce_tmo(p);
+		break;
+	};
+}
+
+enum fsm_event p2p_event(struct port *p, int fd_index)
+{
+	int cnt, fd = p->fda.fd[fd_index];
+	enum fsm_event event = EV_NONE;
+	struct ptp_message *msg, *dup;
+
+	switch (fd_index) {
+	case FD_ANNOUNCE_TIMER:
+	case FD_SYNC_RX_TIMER:
+		pr_debug("port %hu: %s timeout", portnum(p),
+			 fd_index == FD_SYNC_RX_TIMER ? "rx sync" : "announce");
+		if (p->best) {
+			fc_clear(p->best);
+		}
+		port_set_announce_tmo(p);
+		return EV_ANNOUNCE_RECEIPT_TIMEOUT_EXPIRES;
+
+	case FD_DELAY_TIMER:
+		pr_debug("port %hu: delay timeout", portnum(p));
+		port_set_delay_tmo(p);
+		tc_prune(p);
+		return p2p_delay_request(p) ? EV_FAULT_DETECTED : EV_NONE;
+
+	case FD_QUALIFICATION_TIMER:
+		pr_debug("port %hu: qualification timeout", portnum(p));
+		return EV_QUALIFICATION_TIMEOUT_EXPIRES;
+
+	case FD_MANNO_TIMER:
+	case FD_SYNC_TX_TIMER:
+		pr_err("unexpected timer expiration");
+		return EV_NONE;
+
+	case FD_RTNL:
+		pr_debug("port %hu: received link status notification", portnum(p));
+		rtnl_link_status(fd, p->name, port_link_status, p);
+		if (p->link_status == (LINK_UP|LINK_STATE_CHANGED)) {
+			return EV_FAULT_CLEARED;
+		} else if ((p->link_status == (LINK_DOWN|LINK_STATE_CHANGED)) ||
+			   (p->link_status & TS_LABEL_CHANGED)) {
+			return EV_FAULT_DETECTED;
+		} else {
+			return EV_NONE;
+		}
+	}
+
+	msg = msg_allocate();
+	if (!msg) {
+		return EV_FAULT_DETECTED;
+	}
+	msg->hwts.type = p->timestamping;
+
+	cnt = transport_recv(p->trp, fd, msg);
+	if (cnt <= 0) {
+		pr_err("port %hu: recv message failed", portnum(p));
+		msg_put(msg);
+		return EV_FAULT_DETECTED;
+	}
+	if (msg_sots_valid(msg)) {
+		ts_add(&msg->hwts.ts, -p->rx_timestamp_offset);
+	}
+	if (msg->header.flagField[0] & UNICAST) {
+		pl_warning(600, "cannot switch unicast messages!");
+		msg_put(msg);
+		return EV_NONE;
+	}
+
+	dup = msg_duplicate(msg, cnt);
+	if (!dup) {
+		msg_put(msg);
+		return EV_NONE;
+	}
+	if (tc_ignore(p, dup)) {
+		msg_put(dup);
+		dup = NULL;
+	}
+
+	switch (msg_type(msg)) {
+	case SYNC:
+		if (tc_fwd_sync(p, msg)) {
+			event = EV_FAULT_DETECTED;
+			break;
+		}
+		if (dup) {
+			process_sync(p, dup);
+		}
+		break;
+	case DELAY_REQ:
+		break;
+	case PDELAY_REQ:
+		if (dup && process_pdelay_req(p, dup)) {
+			event = EV_FAULT_DETECTED;
+		}
+		break;
+	case PDELAY_RESP:
+		if (dup && process_pdelay_resp(p, dup)) {
+			event = EV_FAULT_DETECTED;
+		}
+		break;
+	case FOLLOW_UP:
+		if (tc_fwd_folup(p, msg)) {
+			event = EV_FAULT_DETECTED;
+			break;
+		}
+		if (dup) {
+			process_follow_up(p, dup);
+		}
+		break;
+	case DELAY_RESP:
+		break;
+	case PDELAY_RESP_FOLLOW_UP:
+		if (dup) {
+			process_pdelay_resp_fup(p, dup);
+		}
+		break;
+	case ANNOUNCE:
+		if (tc_forward(p, msg)) {
+			event = EV_FAULT_DETECTED;
+			break;
+		}
+		if (dup && process_announce(p, dup)) {
+			event = EV_STATE_DECISION_EVENT;
+		}
+		break;
+	case SIGNALING:
+	case MANAGEMENT:
+		if (tc_forward(p, msg)) {
+			event = EV_FAULT_DETECTED;
+		}
+		break;
+	}
+
+	msg_put(msg);
+	if (dup) {
+		msg_put(dup);
+	}
+	return event;
+}

port.c

@@ -2788,6 +2788,9 @@ struct port *port_open(int phc_index,
 		p->event = bc_event;
 		break;
 	case CLOCK_TYPE_P2P:
+		p->dispatch = p2p_dispatch;
+		p->event = p2p_event;
+		break;
 	case CLOCK_TYPE_E2E:
 	case CLOCK_TYPE_MANAGEMENT:
 		return NULL;
@@ -2841,6 +2844,10 @@ struct port *port_open(int phc_index,
 	p->delayMechanism = config_get_int(cfg, p->name, "delay_mechanism");
 	p->versionNumber = PTP_VERSION;
 
+	if (number && type == CLOCK_TYPE_P2P && p->delayMechanism != DM_P2P) {
+		pr_err("port %d: P2P TC needs P2P ports", number);
+		goto err_port;
+	}
 	if (p->hybrid_e2e && p->delayMechanism != DM_E2E) {
 		pr_warning("port %d: hybrid_e2e only works with E2E", number);
 	}

port_private.h

@@ -135,6 +135,9 @@ struct port {
 
 #define portnum(p) (p->portIdentity.portNumber)
 
+void p2p_dispatch(struct port *p, enum fsm_event event, int mdiff);
+enum fsm_event p2p_event(struct port *p, int fd_index);
+
 int clear_fault_asap(struct fault_interval *faint);
 void delay_req_prune(struct port *p);
 void fc_clear(struct foreign_clock *fc);

tc.c

@@ -64,6 +64,10 @@ static int tc_blocked(struct port *q, struct port *p, struct ptp_message *m)
 	if (!q->tc_spanning_tree) {
 		return 0;
 	}
+	/* Forward frames in the wrong domain unconditionally. */
+	if (m->header.domainNumber != clock_domain_number(p->clock)) {
+		return 0;
+	}
 	/* Ingress state */
 	s = port_state(q);
 	switch (s) {