pppoe: Add support to 'ignore-ingress-ppp-brd' feature for pppoe-bundle

This feature ensure that when interface are part of the same pppoe-bundle
then PPP frame broadcast are ignored. In some networking design, having
multiple interface into the same L2 segment can lead to L2 broadcast
during MAC learning process at switch side. PPP is specialy sensitive
to broadcast since it can force unappropriate state transition.

This feature configured for a pppoe-bundle ensure that ingress PPP frame
on diffrent ifindex as the one used during session init are silently
ignored.

This feature is an opt-in setting, since on some others networking
design ones could want to setup asymetric L2 path for ingress and
egress.

This feature is made available via VTY 'ignore-ingress-ppp-brd' in
pppoe-bundle configuration.

src/gtp_pppoe.c

@@ -290,7 +290,7 @@ gtp_pppoe_ingress(pkt_t *pkt, void *arg)
 }
 
 static int
-gtp_pppoe_socket_init(gtp_pppoe_t *pppoe, uint16_t proto)
+gtp_pppoe_socket_init(gtp_pppoe_t *pppoe, uint16_t proto, int id)
 {
 	struct sockaddr_ll sll;
 	int fd, ret;
@@ -306,15 +306,15 @@ gtp_pppoe_socket_init(gtp_pppoe_t *pppoe, uint16_t proto)
 	fd = if_setsockopt_promisc(fd, sll.sll_ifindex, true);
 	if (fd < 0) {
 		log_message(LOG_INFO, "%s(): #%d : Error creating pppoe channel on interface %s (%m)"
-				    , __FUNCTION__
+				    , __FUNCTION__, id
 				    , pppoe->ifname);
 		return -1;
 	}
 
 	ret = bind(fd, (struct sockaddr *) &sll, sizeof(sll));
 	if (ret < 0) {
 		log_message(LOG_INFO, "%s(): #%d : Error binding pppoe channel on interface %s (%m)"
-				    , __FUNCTION__
+				    , __FUNCTION__, id
 				    , pppoe->ifname);
 		close(fd);
 		return -1;
@@ -341,7 +341,7 @@ gtp_pppoe_worker_task(void *arg)
 	prctl(PR_SET_NAME, pname, 0, 0, 0, 0);
 
 	/* Socket init */
-	w->fd = gtp_pppoe_socket_init(pppoe, w->proto);
+	w->fd = gtp_pppoe_socket_init(pppoe, w->proto, w->id);
 	if (w->fd < 0)
 		return NULL;
 

src/gtp_pppoe_proto.c

@@ -571,6 +571,15 @@ pppoe_dispatch_disc_pkt(gtp_pppoe_t *pppoe, pkt_t *pkt)
 		off += len;
 	}
 breakbreak:
+	/* Using PPPoE bundle, PPP frames could be broadcasted to every interfaces
+	 * part of the bundle. if "ignore-ingress-ppp-brd" feature is used then
+	 * only take care of pkt on the same interface as the one used during
+	 * session init */
+	if (s && s->pppoe->bundle &&
+	    __test_bit(PPPOE_FL_IGNORE_INGRESS_PPP_BRD_BIT, &s->pppoe->bundle->flags) &&
+	    (s->pppoe->ifindex != pppoe->ifindex))
+		return;
+
 	switch (code) {
 	case PPPOE_CODE_PADI:
 	case PPPOE_CODE_PADR:
@@ -704,5 +713,15 @@ pppoe_dispatch_session_pkt(gtp_pppoe_t *pppoe, pkt_t *pkt)
 	}
 
 	pkt_buffer_put_data(pkt->pbuff, off);
+
+	/* Using PPPoE bundle, PPP frames could be broadcasted to every interfaces
+	 * part of the bundle. if "ignore-ingress-ppp-brd" feature is used then
+	 * only take care of pkt on the same interface as the one used during
+	 * session init */
+	if (sp->pppoe->bundle &&
+	    __test_bit(PPPOE_FL_IGNORE_INGRESS_PPP_BRD_BIT, &sp->pppoe->bundle->flags) &&
+	    (sp->pppoe->ifindex != pppoe->ifindex))
+		return;
+
 	sppp_input(sp->s_ppp, pkt);
 }

src/gtp_pppoe_vty.c

@@ -581,6 +581,37 @@ DEFUN(pppoe_bundle_instance,
 	return CMD_SUCCESS;
 }
 
+DEFUN(pppoe_bundle_ignore_ingress_ppp_brd,
+      pppoe_bundle_ignore_ingress_ppp_brd_cmd,
+      "ignore-ingress-ppp-brd",
+      "Ignore Ingress PPP broadcast messages\n")
+{
+	gtp_pppoe_bundle_t *bundle = vty->index;
+	gtp_pppoe_t *pppoe;
+
+	pppoe = gtp_pppoe_bundle_instance_prepare(vty, bundle, argc, argv);
+	if (!pppoe)
+		return CMD_WARNING;
+
+	__set_bit(PPPOE_FL_IGNORE_INGRESS_PPP_BRD_BIT, &bundle->flags);
+	return CMD_SUCCESS;
+}
+
+DEFUN(no_pppoe_bundle_ignore_ingress_ppp_brd,
+      no_pppoe_bundle_ignore_ingress_ppp_brd_cmd,
+      "no ignore-ingress-ppp-brd",
+      "Allow Ingress PPP broadcast messages\n")
+{
+	gtp_pppoe_bundle_t *bundle = vty->index;
+	gtp_pppoe_t *pppoe;
+
+	pppoe = gtp_pppoe_bundle_instance_prepare(vty, bundle, argc, argv);
+	if (!pppoe)
+		return CMD_WARNING;
+
+	__clear_bit(PPPOE_FL_IGNORE_INGRESS_PPP_BRD_BIT, &bundle->flags);
+	return CMD_SUCCESS;
+}
 
 /*
  *	Show commands
@@ -732,11 +763,11 @@ gtp_config_pppoe_bundle_write(vty_t *vty)
 
 	list_for_each_entry(bundle, l, next) {
 		vty_out(vty, "pppoe-bundle %s%s", bundle->name, VTY_NEWLINE);
+		if (__test_bit(PPPOE_FL_IGNORE_INGRESS_PPP_BRD_BIT, &bundle->flags))
+			vty_out(vty, " ignore-ingress-ppp-brd%s", VTY_NEWLINE);
 		for (i = 0; i < PPPOE_BUNDLE_MAXSIZE && bundle->pppoe[i]; i++) {
 			pppoe = bundle->pppoe[i];
-			vty_out(vty, " instance %s%s"
-				   , pppoe->name
-				   , VTY_NEWLINE);
+			vty_out(vty, " instance %s%s", pppoe->name, VTY_NEWLINE);
 		}
 		vty_out(vty, "!%s", VTY_NEWLINE);
 	}
@@ -782,6 +813,8 @@ gtp_pppoe_vty_init(void)
 	install_element(CONFIG_NODE, &no_pppoe_bundle_cmd);
 
 	install_element(PPPOE_BUNDLE_NODE, &pppoe_bundle_instance_cmd);
+	install_element(PPPOE_BUNDLE_NODE, &pppoe_bundle_ignore_ingress_ppp_brd_cmd);
+	install_element(PPPOE_BUNDLE_NODE, &no_pppoe_bundle_ignore_ingress_ppp_brd_cmd);
 
 	/* Install show commands. */
 	install_element(VIEW_NODE, &show_pppoe_cmd);

src/include/gtp_pppoe.h

@@ -131,6 +131,7 @@ enum pppoe_flags {
 	PPPOE_FL_LCP_MAX_TERMINATE_BIT,
 	PPPOE_FL_LCP_MAX_CONFIGURE_BIT,
 	PPPOE_FL_LCP_MAX_FAILURE_BIT,
+	PPPOE_FL_IGNORE_INGRESS_PPP_BRD_BIT,
 };
 
 struct rps_opts {
@@ -164,7 +165,10 @@ typedef struct _gtp_pppoe_bundle {
 
 	struct _gtp_pppoe	**pppoe;
 	int			instance_idx;
+
 	list_head_t		next;
+
+	unsigned long		flags;
 } gtp_pppoe_bundle_t;
 
 typedef struct _gtp_pppoe {