zebra, lib, vtysh: Add CLI cmd to set/unset SRv6 encap source address

- Add a new node `SRV6_ENCAP_NODE` to the CLI graph. This node allows
users to configure encapsulation parameters for SRv6, including the
source address of the outer encapsulating IPv6 header.

- Install a new CLI command `source-address` under the
`SRV6_ENCAP_NODE` node. This command is used to configure the source
address of the outer encapsulating IPv6 header.

- Install a new CLI command `no source-address` under the
`SRV6_ENCAP_NODE` node. This command is used to unset the
source address of the outer encapsulating IPv6 header and restore the
default source address.

Examples:

```
router# segment-routing
router(sr)# srv6
router(srv6)# encapsulation
router(srv6-encap)# source-address fc00:0:1::1
```

```
router# segment-routing
router(sr)# srv6
router(srv6)# encapsulation
router(srv6-encap)# no source-address
```

Signed-off-by: Carmine Scarpitta <carmine.scarpitta@uniroma2.it>

lib/command.h

@@ -160,6 +160,7 @@ enum node_type {
 	SRV6_NODE,		 /* SRv6 node */
 	SRV6_LOCS_NODE,		 /* SRv6 locators node */
 	SRV6_LOC_NODE,		 /* SRv6 locator node */
+	SRV6_ENCAP_NODE,		 /* SRv6 encapsulation node */
 	VTY_NODE,		 /* Vty node. */
 	FPM_NODE,		 /* Dataplane FPM node. */
 	LINK_PARAMS_NODE,	/* Link-parameters node */

vtysh/vtysh.c

@@ -1335,6 +1335,13 @@ static struct cmd_node srv6_loc_node = {
 	.prompt = "%s(config-srv6-locator)# ",
 };
 
+static struct cmd_node srv6_encap_node = {
+	.name = "srv6-encap",
+	.node = SRV6_ENCAP_NODE,
+	.parent_node = SRV6_NODE,
+	.prompt = "%s(config-srv6-encap)# "
+};
+
 #ifdef HAVE_PBRD
 static struct cmd_node pbr_map_node = {
 	.name = "pbr-map",
@@ -1692,6 +1699,14 @@ DEFUNSH(VTYSH_ZEBRA, srv6_locator, srv6_locator_cmd,
 	return CMD_SUCCESS;
 }
 
+DEFUNSH(VTYSH_ZEBRA, srv6_encap, srv6_encap_cmd,
+	"encapsulation",
+	"Segment Routing SRv6 encapsulation\n")
+{
+	vty->node = SRV6_ENCAP_NODE;
+	return CMD_SUCCESS;
+}
+
 #ifdef HAVE_BGPD
 DEFUNSH(VTYSH_BGPD, router_bgp, router_bgp_cmd,
 	"router bgp [ASNUM [<view|vrf> VIEWVRFNAME] [as-notation <dot|dot+|plain>]]",
@@ -2507,6 +2522,14 @@ DEFUNSH(VTYSH_ZEBRA, exit_srv6_loc_config, exit_srv6_loc_config_cmd, "exit",
 	return CMD_SUCCESS;
 }
 
+DEFUNSH(VTYSH_ZEBRA, exit_srv6_encap, exit_srv6_encap_cmd, "exit",
+	"Exit from SRv6-encapsulation configuration mode\n")
+{
+	if (vty->node == SRV6_ENCAP_NODE)
+		vty->node = SRV6_NODE;
+	return CMD_SUCCESS;
+}
+
 #ifdef HAVE_RIPD
 DEFUNSH(VTYSH_RIPD, vtysh_exit_ripd, vtysh_exit_ripd_cmd, "exit",
 	"Exit current mode and down to previous mode\n")
@@ -5090,6 +5113,7 @@ void vtysh_init_vty(void)
 	install_element(SRV6_NODE, &srv6_locators_cmd);
 	install_element(SRV6_NODE, &exit_srv6_config_cmd);
 	install_element(SRV6_NODE, &vtysh_end_all_cmd);
+	install_element(SRV6_NODE, &srv6_encap_cmd);
 
 	install_node(&srv6_locs_node);
 	install_element(SRV6_LOCS_NODE, &srv6_locator_cmd);
@@ -5100,6 +5124,10 @@ void vtysh_init_vty(void)
 	install_element(SRV6_LOC_NODE, &exit_srv6_loc_config_cmd);
 	install_element(SRV6_LOC_NODE, &vtysh_end_all_cmd);
 
+	install_node(&srv6_encap_node);
+	install_element(SRV6_ENCAP_NODE, &exit_srv6_encap_cmd);
+	install_element(SRV6_ENCAP_NODE, &vtysh_end_all_cmd);
+
 	install_element(ENABLE_NODE, &vtysh_show_running_config_cmd);
 	install_element(ENABLE_NODE, &vtysh_copy_running_config_cmd);
 	install_element(ENABLE_NODE, &vtysh_copy_to_running_cmd);

zebra/zebra_srv6.c

@@ -409,6 +409,23 @@ int release_daemon_srv6_locator_chunks(struct zserv *client)
 	return count;
 }
 
+void zebra_srv6_encap_src_addr_set(struct in6_addr *encap_src_addr)
+{
+	struct zebra_srv6 *srv6 = zebra_srv6_get_default();
+
+	if (!encap_src_addr)
+		return;
+
+	memcpy(&srv6->encap_src_addr, encap_src_addr, sizeof(struct in6_addr));
+}
+
+void zebra_srv6_encap_src_addr_unset(void)
+{
+	struct zebra_srv6 *srv6 = zebra_srv6_get_default();
+
+	memset(&srv6->encap_src_addr, 0, sizeof(struct in6_addr));
+}
+
 void zebra_srv6_terminate(void)
 {
 	struct srv6_locator *locator;

zebra/zebra_srv6.h

@@ -19,6 +19,9 @@
 /* SRv6 instance structure. */
 struct zebra_srv6 {
 	struct list *locators;
+
+	/* Source address for SRv6 encapsulation */
+	struct in6_addr encap_src_addr;
 };
 
 /* declare hooks for the basic API, so that it can be specialized or served
@@ -68,4 +71,7 @@ extern void srv6_manager_release_locator_chunk_call(struct zserv *client,
 extern int srv6_manager_client_disconnect_cb(struct zserv *client);
 extern int release_daemon_srv6_locator_chunks(struct zserv *client);
 
+extern void zebra_srv6_encap_src_addr_set(struct in6_addr *src_addr);
+extern void zebra_srv6_encap_src_addr_unset(void);
+
 #endif /* _ZEBRA_SRV6_H */

zebra/zebra_srv6_vty.c

@@ -61,6 +61,13 @@ static struct cmd_node srv6_loc_node = {
 	.prompt = "%s(config-srv6-locator)# "
 };
 
+static struct cmd_node srv6_encap_node = {
+	.name = "srv6-encap",
+	.node = SRV6_ENCAP_NODE,
+	.parent_node = SRV6_NODE,
+	.prompt = "%s(config-srv6-encap)# "
+};
+
 DEFUN (show_srv6_locator,
        show_srv6_locator_cmd,
        "show segment-routing srv6 locator [json]",
@@ -391,6 +398,38 @@ DEFPY (locator_behavior,
 	return CMD_SUCCESS;
 }
 
+DEFUN_NOSH (srv6_encap,
+            srv6_encap_cmd,
+            "encapsulation",
+            "Segment Routing SRv6 encapsulation\n")
+{
+	vty->node = SRV6_ENCAP_NODE;
+	return CMD_SUCCESS;
+}
+
+DEFPY (srv6_src_addr,
+       srv6_src_addr_cmd,
+       "source-address X:X::X:X$encap_src_addr",
+       "Segment Routing SRv6 source address\n"
+       "Specify source address for SRv6 encapsulation\n")
+{
+	zebra_srv6_encap_src_addr_set(&encap_src_addr);
+	dplane_srv6_encap_srcaddr_set(&encap_src_addr, NS_DEFAULT);
+	return CMD_SUCCESS;
+}
+
+DEFPY (no_srv6_src_addr,
+       no_srv6_src_addr_cmd,
+       "no source-address [X:X::X:X$encap_src_addr]",
+       NO_STR
+       "Segment Routing SRv6 source address\n"
+       "Specify source address for SRv6 encapsulation\n")
+{
+	zebra_srv6_encap_src_addr_unset();
+	dplane_srv6_encap_srcaddr_set(&in6addr_any, NS_DEFAULT);
+	return CMD_SUCCESS;
+}
+
 static int zebra_sr_config(struct vty *vty)
 {
 	struct zebra_srv6 *srv6 = zebra_srv6_get_default();
@@ -444,22 +483,27 @@ void zebra_srv6_vty_init(void)
 	install_node(&srv6_node);
 	install_node(&srv6_locs_node);
 	install_node(&srv6_loc_node);
+	install_node(&srv6_encap_node);
 	install_default(SEGMENT_ROUTING_NODE);
 	install_default(SRV6_NODE);
 	install_default(SRV6_LOCS_NODE);
 	install_default(SRV6_LOC_NODE);
+	install_default(SRV6_ENCAP_NODE);
 
 	/* Command for change node */
 	install_element(CONFIG_NODE, &segment_routing_cmd);
 	install_element(SEGMENT_ROUTING_NODE, &srv6_cmd);
 	install_element(SEGMENT_ROUTING_NODE, &no_srv6_cmd);
 	install_element(SRV6_NODE, &srv6_locators_cmd);
+	install_element(SRV6_NODE, &srv6_encap_cmd);
 	install_element(SRV6_LOCS_NODE, &srv6_locator_cmd);
 	install_element(SRV6_LOCS_NODE, &no_srv6_locator_cmd);
 
 	/* Command for configuration */
 	install_element(SRV6_LOC_NODE, &locator_prefix_cmd);
 	install_element(SRV6_LOC_NODE, &locator_behavior_cmd);
+	install_element(SRV6_ENCAP_NODE, &srv6_src_addr_cmd);
+	install_element(SRV6_ENCAP_NODE, &no_srv6_src_addr_cmd);
 
 	/* Command for operation */
 	install_element(VIEW_NODE, &show_srv6_locator_cmd);