bgpd: Allow bgp to control the DSCP session TOS value

Allow BGP to control the TOS DSCP value in the tcp header
via a new command at the bgp global level `bgp session-dscp <0-63>`

Signed-off-by: Donald Sharp <sharpd@nvidia.com>
Signed-off-by: Pavel Shirhov <pavelsh@microsoft.com>

4 files changed, 43 insertions, 8 deletions

diff --git a/bgpd/bgp_network.c b/bgpd/bgp_network.c
index e702ee4fd..77e2a0f53 100644
--- a/bgpd/bgp_network.c
+++ b/bgpd/bgp_network.c
@@ -741,11 +741,9 @@ int bgp_connect(struct peer *peer)
 #ifdef IPTOS_PREC_INTERNETCONTROL
 	frr_with_privs(&bgpd_privs) {
 		if (sockunion_family(&peer->su) == AF_INET)
-			setsockopt_ipv4_tos(peer->fd,
-					    IPTOS_PREC_INTERNETCONTROL);
+			setsockopt_ipv4_tos(peer->fd, bm->tcp_dscp);
 		else if (sockunion_family(&peer->su) == AF_INET6)
-			setsockopt_ipv6_tclass(peer->fd,
-					       IPTOS_PREC_INTERNETCONTROL);
+			setsockopt_ipv6_tclass(peer->fd, bm->tcp_dscp);
 	}
 #endif
 
@@ -822,10 +820,9 @@ static int bgp_listener(int sock, struct sockaddr *sa, socklen_t salen,
 
 #ifdef IPTOS_PREC_INTERNETCONTROL
 		if (sa->sa_family == AF_INET)
-			setsockopt_ipv4_tos(sock, IPTOS_PREC_INTERNETCONTROL);
+			setsockopt_ipv4_tos(sock, bm->tcp_dscp);
 		else if (sa->sa_family == AF_INET6)
-			setsockopt_ipv6_tclass(sock,
-					       IPTOS_PREC_INTERNETCONTROL);
+			setsockopt_ipv6_tclass(sock, bm->tcp_dscp);
 #endif
 
 		sockopt_v6only(sa->sa_family, sock);
diff --git a/bgpd/bgp_vty.c b/bgpd/bgp_vty.c
index 4a3688be2..9e22c6cdb 100644
--- a/bgpd/bgp_vty.c
+++ b/bgpd/bgp_vty.c
@@ -1568,6 +1568,32 @@ DEFUN (no_router_bgp,
 	return CMD_SUCCESS;
 }
 
+/* bgp session-dscp */
+
+DEFPY (bgp_session_dscp,
+       bgp_session_dscp_cmd,
+       "bgp session-dscp (0-63)$dscp",
+       BGP_STR
+       "Override default (C6) bgp TCP session DSCP value\n"
+       "Manually configured dscp parameter\n")
+{
+	bm->tcp_dscp = dscp << 2;
+
+	return CMD_SUCCESS;
+}
+
+DEFPY (no_bgp_session_dscp,
+       no_bgp_session_dscp_cmd,
+       "no bgp session-dscp [(0-63)]",
+       NO_STR
+       BGP_STR
+       "Override default (C6) bgp TCP session DSCP value\n"
+       "Manually configured dscp parameter\n")
+{
+	bm->tcp_dscp = IPTOS_PREC_INTERNETCONTROL;
+
+	return CMD_SUCCESS;
+}
 
 /* BGP router-id.  */
 
@@ -17126,6 +17152,10 @@ int bgp_config_write(struct vty *vty)
 	if (CHECK_FLAG(bm->flags, BM_FLAG_SEND_EXTRA_DATA_TO_ZEBRA))
 		vty_out(vty, "bgp send-extra-data zebra\n");
 
+	/* BGP session DSCP value */
+	if (bm->tcp_dscp != IPTOS_PREC_INTERNETCONTROL)
+		vty_out(vty, "bgp session-dscp %u\n", bm->tcp_dscp >> 2);
+
 	/* BGP configuration. */
 	for (ALL_LIST_ELEMENTS(bm->bgp, mnode, mnnode, bgp)) {
 
@@ -17829,6 +17859,10 @@ void bgp_vty_init(void)
 	/* "no router bgp" commands. */
 	install_element(CONFIG_NODE, &no_router_bgp_cmd);
 
+	/* "bgp session-dscp command */
+	install_element(CONFIG_NODE, &bgp_session_dscp_cmd);
+	install_element(CONFIG_NODE, &no_bgp_session_dscp_cmd);
+
 	/* "bgp router-id" commands. */
 	install_element(BGP_NODE, &bgp_router_id_cmd);
 	install_element(BGP_NODE, &no_bgp_router_id_cmd);
diff --git a/bgpd/bgpd.c b/bgpd/bgpd.c
index 779540772..7d284f28b 100644
--- a/bgpd/bgpd.c
+++ b/bgpd/bgpd.c
@@ -3259,7 +3259,6 @@ static struct bgp *bgp_create(as_t *as, const char *name,
 
 	bgp->evpn_info = XCALLOC(MTYPE_BGP_EVPN_INFO,
 				 sizeof(struct bgp_evpn_info));
-
 	bgp_evpn_init(bgp);
 	bgp_evpn_vrf_es_init(bgp);
 	bgp_pbr_init(bgp);
@@ -7854,6 +7853,7 @@ void bgp_master_init(struct thread_master *master, const int buffer_size,
 	bm->terminating = false;
 	bm->socket_buffer = buffer_size;
 	bm->wait_for_fib = false;
+	bm->tcp_dscp = IPTOS_PREC_INTERNETCONTROL;
 
 	bgp_mac_init();
 	/* init the rd id space.
diff --git a/bgpd/bgpd.h b/bgpd/bgpd.h
index af07cb4c1..6b58c101a 100644
--- a/bgpd/bgpd.h
+++ b/bgpd/bgpd.h
@@ -171,6 +171,10 @@ struct bgp_master {
 #define BM_FLAG_SEND_EXTRA_DATA_TO_ZEBRA (1 << 1)
 
 	bool terminating;	/* global flag that sigint terminate seen */
+
+	/* DSCP value for TCP sessions */
+	uint8_t tcp_dscp;
+
 	QOBJ_FIELDS;
 };
 DECLARE_QOBJ_TYPE(bgp_master);