From b1e1ccf7c33d971c2a05a2d607c76e155cb384b0 Mon Sep 17 00:00:00 2001
From: "Nicholas J. Kain" <nicholas@kain.us>
Date: Wed, 19 Mar 2014 01:13:11 -0400
Subject: [PATCH] Add support for setting the metric for the default GW route.

---
 ndhc/ifset.c |  3 ++-
 ndhc/ndhc.c  | 23 ++++++++++++++++++++++-
 ndhc/ndhc.h  |  1 +
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/ndhc/ifset.c b/ndhc/ifset.c
index 2cef4be..11221ca 100644
--- a/ndhc/ifset.c
+++ b/ndhc/ifset.c
@@ -595,7 +595,8 @@ void perform_router(const char *str_router, size_t len)
         return;
     }
 
-    if (rtnl_set_default_gw_v4(fd, router.s_addr, 0) < 0)
+    if (rtnl_set_default_gw_v4(fd, router.s_addr,
+                               client_config.metric) < 0)
         log_line("%s: (%s) failed to set route: %s",
                  client_config.interface, __func__, strerror(errno));
     else
diff --git a/ndhc/ndhc.c b/ndhc/ndhc.c
index 9278fdb..39c0a88 100644
--- a/ndhc/ndhc.c
+++ b/ndhc/ndhc.c
@@ -48,6 +48,7 @@
 #include <errno.h>
 #include <pwd.h>
 #include <grp.h>
+#include <limits.h>
 
 #include "ndhc.h"
 #include "ndhc-defines.h"
@@ -89,6 +90,7 @@ struct client_config_t client_config = {
     .interface = "eth0",
     .arp = "\0\0\0\0\0\0",
     .clientid_len = 0,
+    .metric = 0,
 };
 
 static void show_usage(void)
@@ -124,6 +126,7 @@ static void show_usage(void)
 "  -W, --arp-probe-num             Number of ARP probes before lease is ok\n"
 "  -m, --arp-probe-min             Min ms to wait for ARP response\n"
 "  -M, --arp-probe-max             Max ms to wait for ARP response\n"
+"  -t, --gw-metric                 Route metric for default gw (default: 0)\n"
 "  -R, --resolve-conf=FILE         Path to resolv.conf or equivalent\n"
 "  -H, --dhcp-hostname             Allow DHCP to set machine hostname\n"
 "  -v, --version                   Display version\n"
@@ -422,6 +425,7 @@ int main(int argc, char **argv)
         {"arp-probe-num",      required_argument,  0, 'W'},
         {"arp-probe-min",      required_argument,  0, 'm'},
         {"arp-probe-max",      required_argument,  0, 'M'},
+        {"gw-metric",          required_argument,  0, 't'},
         {"resolv-conf",        required_argument,  0, 'R'},
         {"dhcp-set-hostname",  no_argument,        0, 'H'},
         {"version",            no_argument,        0, 'v'},
@@ -431,7 +435,7 @@ int main(int argc, char **argv)
 
     while (1) {
         int c;
-        c = getopt_long(argc, argv, "c:fbp:P:l:h:i:nqr:V:u:U:C:s:Sdw:W:m:M:R:Hv?",
+        c = getopt_long(argc, argv, "c:fbp:P:l:h:i:nqr:V:u:U:C:s:Sdw:W:m:M:t:R:Hv?",
                         arg_options, NULL);
         if (c == -1) break;
 
@@ -572,6 +576,23 @@ int main(int argc, char **argv)
                 strnkcpy(client_config.vendor, optarg,
                          sizeof client_config.vendor);
                 break;
+            case 't': {
+                char *p;
+                long mt = strtol(optarg, &p, 10);
+                if (p == optarg) {
+                    log_error("gw-metric arg '%s' isn't a valid number",
+                              optarg);
+                    exit(EXIT_FAILURE);
+                }
+                if (mt > INT_MAX) {
+                    log_error("gw-metric arg '%s' is too large", optarg);
+                    exit(EXIT_FAILURE);
+                }
+                if (mt < 0)
+                    mt = 0;
+                client_config.metric = (int)mt;
+                break;
+            }
             case 'R':
                 strnkcpy(resolv_conf_d, optarg, sizeof resolv_conf_d);
                 break;
diff --git a/ndhc/ndhc.h b/ndhc/ndhc.h
index 0fcf3a1..bd271de 100644
--- a/ndhc/ndhc.h
+++ b/ndhc/ndhc.h
@@ -60,6 +60,7 @@ struct client_config_t {
     uint8_t clientid_len;        // Length of the clientid
     char hostname[64];           // Optional hostname to use
     char vendor[64];             // Vendor identification that will be sent
+    int metric;                  // Metric for the default route
     int ifindex;                 // Index number of the interface to use
     uint8_t arp[6];              // Our arp address
 };