If ifchd interactions fail, terminate.

Ideally we would pause and resume state, but for now just bail out.
If ndhc is process-supervised, it will recover to the proper state
quickly.

src/arp.c

@@ -468,7 +468,13 @@ void arp_success(struct client_state_t cs[static 1])
     cs->init = 0;
     garp.last_conflict_ts = 0;
     garp.wake_ts[AS_COLLISION_CHECK] = -1;
-    ifchange_bind(cs, &garp.dhcp_packet);
+    if (ifchange_bind(cs, &garp.dhcp_packet) < 0) {
+        // XXX: Not ideal, but assuming that the DHCP process is supervised,
+        // it will recover.  The correct thing to do would be to keep
+        // trying to set the configuration state.
+        suicide("%s: Failed to set the interface IP address and properties!",
+                client_config.interface);
+    }
     if (cs->arpPrevState == DS_RENEWING || cs->arpPrevState == DS_REBINDING) {
         arp_switch_state(cs, AS_DEFENSE);
     } else {

src/ndhc.c

@@ -435,8 +435,10 @@ static void ndhc_main(void) {
     memset(chroot_dir, '\0', sizeof chroot_dir);
     nk_set_uidgid(ndhc_uid, ndhc_gid, NULL, 0);
 
-    if (cs.ifsPrevState != IFS_UP)
+    if (cs.ifsPrevState != IFS_UP) {
-        ifchange_deconfig(&cs);
+        if (ifchange_deconfig(&cs) < 0)
+            suicide("%s: can't deconfigure interface settings", __func__);
+    }
 
     do_ndhc_work();
 }

src/state.c

@@ -107,9 +107,10 @@ static int delay_timeout(struct client_state_t cs[static 1], size_t numpackets)
     return to * 1000 + (nk_random_u32(&cs->rnd32_state) & 0x7fffffffu) % 1000;
 }
 
-static void reinit_shared_deconfig(struct client_state_t cs[static 1])
+static int reinit_shared_deconfig(struct client_state_t cs[static 1])
 {
-    ifchange_deconfig(cs);
+    if (ifchange_deconfig(cs) < 0)
+        return -1;
     arp_close_fd(cs);
     cs->clientAddr = 0;
     num_dhcp_requests = 0;
@@ -118,22 +119,33 @@ static void reinit_shared_deconfig(struct client_state_t cs[static 1])
     memset(&cs->routerArp, 0, sizeof cs->routerArp);
     memset(&cs->serverArp, 0, sizeof cs->serverArp);
     arp_reset_send_stats();
+    return 0;
 }
 
-void reinit_selecting(struct client_state_t cs[static 1], int timeout)
+int reinit_selecting(struct client_state_t cs[static 1], int timeout)
 {
-    reinit_shared_deconfig(cs);
+    if (reinit_shared_deconfig(cs) < 0) {
+        // XXX: This should retry until it succeeds.
+        suicide("%s: (%s) deconfiguring interface failed",
+                client_config.interface, __func__);
+    }
     cs->dhcpState = DS_SELECTING;
     dhcp_wake_ts = curms() + timeout;
     start_dhcp_listen(cs);
+    return 0;
 }
 
-static void set_released(struct client_state_t cs[static 1])
+static int set_released(struct client_state_t cs[static 1])
 {
-    reinit_shared_deconfig(cs);
+    if (reinit_shared_deconfig(cs) < 0) {
+        // XXX: This should retry until it succeeds.
+        suicide("%s: (%s) deconfiguring interface failed",
+                client_config.interface, __func__);
+    }
     cs->dhcpState = DS_RELEASED;
     dhcp_wake_ts = -1;
     stop_dhcp_listen(cs);
+    return 0;
 }
 
 // Triggered after a DHCP lease request packet has been sent and no reply has

src/state.h

@@ -43,7 +43,7 @@ typedef enum {
     DS_NUM_STATES,
 } dhcp_states_t;
 
-void reinit_selecting(struct client_state_t cs[static 1], int timeout);
+int reinit_selecting(struct client_state_t cs[static 1], int timeout);
 
 void packet_action(struct client_state_t cs[static 1],
                    struct dhcpmsg packet[static 1], uint8_t msgtype,