1 files changed, 20 insertions, 7 deletions

diff --git a/networking/ntpd.c b/networking/ntpd.c
index 59607ed23..cfe695631 100644
--- a/networking/ntpd.c
+++ b/networking/ntpd.c
@@ -29,7 +29,7 @@
  */
 
 //usage:#define ntpd_trivial_usage
-//usage:        "[-dnqNw"IF_FEATURE_NTPD_SERVER("l")"] [-S PROG] [-p PEER]..."
+//usage:        "[-dnqNw"IF_FEATURE_NTPD_SERVER("l -I IFACE")"] [-S PROG] [-p PEER]..."
 //usage:#define ntpd_full_usage "\n\n"
 //usage:       "NTP client/server\n"
 //usage:     "\n        -d      Verbose"
@@ -39,6 +39,7 @@
 //usage:     "\n        -w      Do not set time (only query peers), implies -n"
 //usage:        IF_FEATURE_NTPD_SERVER(
 //usage:     "\n        -l      Run as server on port 123"
+//usage:     "\n        -I IFACE Bind server to IFACE, implies -l"
 //usage:        )
 //usage:     "\n        -S PROG Run PROG after stepping time, stratum change, and every 11 mins"
 //usage:     "\n        -p PEER Obtain time from PEER (may be repeated)"
@@ -283,6 +284,7 @@ enum {
         OPT_p = (1 << 5),
         OPT_S = (1 << 6),
         OPT_l = (1 << 7) * ENABLE_FEATURE_NTPD_SERVER,
+        OPT_I = (1 << 8) * ENABLE_FEATURE_NTPD_SERVER,
         /* We hijack some bits for other purposes */
         OPT_qq = (1 << 31),
 };
@@ -301,6 +303,7 @@ struct globals {
         llist_t  *ntp_peers;
 #if ENABLE_FEATURE_NTPD_SERVER
         int      listen_fd;
+        char     *if_name;
 # define G_listen_fd (G.listen_fd)
 #else
 # define G_listen_fd (-1)
@@ -2092,13 +2095,19 @@ static NOINLINE void ntp_init(char **argv)
 
         /* Parse options */
         peers = NULL;
-        opt_complementary = "dd:p::wn"; /* d: counter; p: list; -w implies -n */
+        opt_complementary = "dd:p::wn"         /* -d: counter; -p: list; -w implies -n */
+                IF_FEATURE_NTPD_SERVER(":Il"); /* -I implies -l */
         opts = getopt32(argv,
                         "nqNx" /* compat */
                         "wp:S:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */
+                        IF_FEATURE_NTPD_SERVER("I:") /* compat */
                         "d" /* compat */
                         "46aAbgL", /* compat, ignored */
-                        &peers, &G.script_name, &G.verbose);
+                        &peers,&G.script_name,
+#if ENABLE_FEATURE_NTPD_SERVER
+                        &G.if_name,
+#endif
+                        &G.verbose);
 
 //      if (opts & OPT_x) /* disable stepping, only slew is allowed */
 //              G.time_was_stepped = 1;
@@ -2130,18 +2139,22 @@ static NOINLINE void ntp_init(char **argv)
                 /* -l but no peers: "stratum 1 server" mode */
                 G.stratum = 1;
         }
-        if (!(opts & OPT_n)) {
-                bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO, argv);
-                logmode = LOGMODE_NONE;
-        }
 #if ENABLE_FEATURE_NTPD_SERVER
         G_listen_fd = -1;
         if (opts & OPT_l) {
                 G_listen_fd = create_and_bind_dgram_or_die(NULL, 123);
+                if (opts & OPT_I) {
+                        if (setsockopt_bindtodevice(G_listen_fd, G.if_name))
+                                xfunc_die();
+                }
                 socket_want_pktinfo(G_listen_fd);
                 setsockopt(G_listen_fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
         }
 #endif
+        if (!(opts & OPT_n)) {
+                bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO, argv);
+                logmode = LOGMODE_NONE;
+        }
         /* I hesitate to set -20 prio. -15 should be high enough for timekeeping */
         if (opts & OPT_N)
                 setpriority(PRIO_PROCESS, 0, -15);