iplink: implement support for selecting a master interface

Attaching an interface to a VRF is done by setting the interface's
master. Besides VRF, this can also be used for bridges.

function                                             old     new   delta
set_master                                             -     142    +142
do_iplink                                           1262    1357     +95
packed_usage                                       32546   32539      -7
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/1 up/down: 237/-7)            Total: 230 bytes

Signed-off-by: Jan Luebbe <jluebbe@debian.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 41 insertions, 2 deletions

diff --git a/networking/ip.c b/networking/ip.c
index 665f9bcce..accf90759 100644
--- a/networking/ip.c
+++ b/networking/ip.c
@@ -156,7 +156,8 @@
 //--------------123456789.123456789.123456789.123456789.123456789.123456789.123456789.123....79
 //usage:#define iplink_trivial_usage
 //usage:       /*Usage:iplink*/"set IFACE [up|down] [arp on|off] [multicast on|off]\n"
-//usage:       "        [promisc on|off] [mtu NUM] [name NAME] [qlen NUM] [address MAC]"
+//usage:       "        [promisc on|off] [mtu NUM] [name NAME] [qlen NUM] [address MAC]\n"
+//usage:       "        [master IFACE | nomaster]\n"
 // * short help shows only "set" command, long help continues (with just one "\n")
 // * and shows all other commands:
 //usage:#define iplink_full_usage "\n"
diff --git a/networking/libiproute/iplink.c b/networking/libiproute/iplink.c
index 312283318..2aa8b683b 100644
--- a/networking/libiproute/iplink.c
+++ b/networking/libiproute/iplink.c
@@ -128,6 +128,31 @@ static void set_mtu(char *dev, int mtu)
 }
 
 /* Exits on error */
+static void set_master(char *dev, int master)
+{
+        struct rtnl_handle rth;
+        struct {
+                struct nlmsghdr  n;
+                struct ifinfomsg i;
+                char             buf[1024];
+        } req;
+
+        memset(&req, 0, sizeof(req));
+
+        req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
+        req.n.nlmsg_flags = NLM_F_REQUEST;
+        req.n.nlmsg_type = RTM_NEWLINK;
+        req.i.ifi_family = preferred_family;
+
+        xrtnl_open(&rth);
+        req.i.ifi_index = xll_name_to_index(dev);
+        //printf("master %i for %i\n", master, req.i.ifi_index);
+        addattr_l(&req.n, sizeof(req), IFLA_MASTER, &master, 4);
+        if (rtnl_talk(&rth, &req.n, 0, 0, NULL, NULL, NULL) < 0)
+                xfunc_die();
+}
+
+/* Exits on error */
 static int get_address(char *dev, int *htype)
 {
         struct ifreq ifr;
@@ -200,6 +225,7 @@ static int do_set(char **argv)
         uint32_t flags = 0;
         int qlen = -1;
         int mtu = -1;
+        int master = -1;
         char *newaddr = NULL;
         char *newbrd = NULL;
         struct ifreq ifr0, ifr1;
@@ -209,9 +235,11 @@ static int do_set(char **argv)
         static const char keywords[] ALIGN1 =
                 "up\0""down\0""name\0""mtu\0""qlen\0""multicast\0"
                 "arp\0""promisc\0""address\0"
+                "master\0""nomaster\0"
                 "dev\0" /* must be last */;
         enum { ARG_up = 0, ARG_down, ARG_name, ARG_mtu, ARG_qlen, ARG_multicast,
                 ARG_arp, ARG_promisc, ARG_addr,
+                ARG_master, ARG_nomaster,
                 ARG_dev };
         enum { PARM_on = 0, PARM_off };
         smalluint key;
@@ -243,6 +271,11 @@ static int do_set(char **argv)
                 } else if (key == ARG_addr) {
                         NEXT_ARG();
                         newaddr = *argv;
+                } else if (key == ARG_master) {
+                        NEXT_ARG();
+                        master = xll_name_to_index(*argv);
+                } else if (key == ARG_nomaster) {
+                        master = 0;
                 } else if (key >= ARG_dev) {
                         /* ^^^^^^ ">=" here results in "dev IFACE" treated as default */
                         if (key == ARG_dev) {
@@ -427,6 +460,9 @@ static int do_set(char **argv)
         if (mtu != -1) {
                 set_mtu(dev, mtu);
         }
+        if (master != -1) {
+                set_master(dev, master);
+        }
         if (mask)
                 do_chflags(dev, flags, mask);
         return 0;
@@ -673,6 +709,8 @@ int FAST_FUNC do_iplink(char **argv)
 {
         static const char keywords[] ALIGN1 =
                 "add\0""delete\0""set\0""show\0""lst\0""list\0";
+
+        xfunc_error_retval = 2; //TODO: move up to "ip"? Is it the common rule for all "ip" tools?
         if (*argv) {
                 int key = index_in_substrings(keywords, *argv);
                 if (key < 0) /* invalid argument */
diff --git a/networking/tcpudp.c b/networking/tcpudp.c
index d4c69e0f7..2feb63a01 100644
--- a/networking/tcpudp.c
+++ b/networking/tcpudp.c
@@ -318,7 +318,7 @@ int tcpudpsvd_main(int argc UNUSED_PARAM, char **argv)
         sslser = user;
         client = 0;
         if ((getuid() == 0) && !(opts & OPT_u)) {
-                xfunc_exitcode = 100;
+                xfunc_error_retval = 100;
                 bb_error_msg_and_die(bb_msg_you_must_be_root);
         }
         if (opts & OPT_u)