*: Add and use option for graceful (re)start

Add a new start option "-K" to libfrr to denote a graceful start,
and use it in zebra and bgpd.

zebra will use this option to denote a planned FRR graceful restart
(supporting only bgpd currently) to wait for a route sync completion
from bgpd before cleaning up old stale routes from the FIB. An optional
timer provides an upper-bounds for this cleanup.

bgpd will use this option to denote either a planned FRR graceful
restart or a bgpd-only graceful restart, and this will drive the BGP
GR restarting router procedures.

Signed-off-by: Vivek Venkatraman <vivek@nvidia.com>

1 files changed, 28 insertions, 17 deletions

diff --git a/lib/libfrr.c b/lib/libfrr.c
index 876efe23a8..338a7d0340 100644
--- a/lib/libfrr.c
+++ b/lib/libfrr.c
@@ -102,23 +102,25 @@ static void opt_extend(const struct optspec *os)
 #define OPTION_SCRIPTDIR 1009
 
 static const struct option lo_always[] = {
-	{"help", no_argument, NULL, 'h'},
-	{"version", no_argument, NULL, 'v'},
-	{"daemon", no_argument, NULL, 'd'},
-	{"module", no_argument, NULL, 'M'},
-	{"profile", required_argument, NULL, 'F'},
-	{"pathspace", required_argument, NULL, 'N'},
-	{"vrfdefaultname", required_argument, NULL, 'o'},
-	{"vty_socket", required_argument, NULL, OPTION_VTYSOCK},
-	{"moduledir", required_argument, NULL, OPTION_MODULEDIR},
-	{"scriptdir", required_argument, NULL, OPTION_SCRIPTDIR},
-	{"log", required_argument, NULL, OPTION_LOG},
-	{"log-level", required_argument, NULL, OPTION_LOGLEVEL},
-	{"command-log-always", no_argument, NULL, OPTION_LOGGING},
-	{"limit-fds", required_argument, NULL, OPTION_LIMIT_FDS},
-	{NULL}};
+	{ "help", no_argument, NULL, 'h' },
+	{ "version", no_argument, NULL, 'v' },
+	{ "daemon", no_argument, NULL, 'd' },
+	{ "module", no_argument, NULL, 'M' },
+	{ "profile", required_argument, NULL, 'F' },
+	{ "pathspace", required_argument, NULL, 'N' },
+	{ "vrfdefaultname", required_argument, NULL, 'o' },
+	{ "graceful_restart", optional_argument, NULL, 'K' },
+	{ "vty_socket", required_argument, NULL, OPTION_VTYSOCK },
+	{ "moduledir", required_argument, NULL, OPTION_MODULEDIR },
+	{ "scriptdir", required_argument, NULL, OPTION_SCRIPTDIR },
+	{ "log", required_argument, NULL, OPTION_LOG },
+	{ "log-level", required_argument, NULL, OPTION_LOGLEVEL },
+	{ "command-log-always", no_argument, NULL, OPTION_LOGGING },
+	{ "limit-fds", required_argument, NULL, OPTION_LIMIT_FDS },
+	{ NULL }
+};
 static const struct optspec os_always = {
-	"hvdM:F:N:o:",
+	"hvdM:F:N:o:K::",
 	"  -h, --help         Display this help and exit\n"
 	"  -v, --version      Print program version\n"
 	"  -d, --daemon       Runs in daemon mode\n"
@@ -126,13 +128,15 @@ static const struct optspec os_always = {
 	"  -F, --profile      Use specified configuration profile\n"
 	"  -N, --pathspace    Insert prefix into config & socket paths\n"
 	"  -o, --vrfdefaultname     Set default VRF name.\n"
+	"  -K, --graceful_restart   FRR starting in Graceful Restart mode, with optional route-cleanup timer\n"
 	"      --vty_socket   Override vty socket path\n"
 	"      --moduledir    Override modules directory\n"
 	"      --scriptdir    Override scripts directory\n"
 	"      --log          Set Logging to stdout, syslog, or file:<name>\n"
 	"      --log-level    Set Logging Level to use, debug, info, warn, etc\n"
 	"      --limit-fds    Limit number of fds supported\n",
-	lo_always};
+	lo_always
+};
 
 static bool logging_to_stdout = false; /* set when --log stdout specified */
 
@@ -358,6 +362,8 @@ void frr_preinit(struct frr_daemon_info *daemon, int argc, char **argv)
 	strlcpy(frr_protonameinst, di->logname, sizeof(frr_protonameinst));
 
 	di->cli_mode = FRR_CLI_CLASSIC;
+	di->graceful_restart = false;
+	di->gr_cleanup_time = 0;
 
 	/* we may be starting with extra FDs open for whatever purpose,
 	 * e.g. logging, some module, etc.  Recording them here allows later
@@ -520,6 +526,11 @@ static int frr_opt(int opt)
 		di->db_file = optarg;
 		break;
 #endif
+	case 'K':
+		di->graceful_restart = true;
+		if (optarg)
+			di->gr_cleanup_time = atoi(optarg);
+		break;
 	case 'C':
 		if (di->flags & FRR_NO_SPLIT_CONFIG)
 			return 1;