From 170f87c0e7ccf1fce3c614c36ada1f77785ad4eb Mon Sep 17 00:00:00 2001
From: "Nicholas J. Kain" <nicholas@kain.us>
Date: Sat, 14 Feb 2015 19:10:23 -0500
Subject: [PATCH] Propagate returns through ifchange_(deconfig|bind).

While doing so remove unnecessary argument null checks and
make sure not to alter the stored interface state if the
ifch requests failed.
---
 src/ifchange.c | 33 ++++++++++++++++++---------------
 src/ifchange.h |  6 +++---
 src/ndhc.c     |  1 -
 3 files changed, 21 insertions(+), 19 deletions(-)

diff --git a/src/ifchange.c b/src/ifchange.c
index 0dcf4bc..b855572 100644
--- a/src/ifchange.c
+++ b/src/ifchange.c
@@ -225,19 +225,23 @@ static int ifchwrite(const char buf[static 1], size_t count)
     return -1;
 }
 
-void ifchange_deconfig(struct client_state_t cs[static 1])
+int ifchange_deconfig(struct client_state_t cs[static 1])
 {
     char buf[256];
+    int ret = -1;
 
     if (cs->ifDeconfig)
-        return;
-    cs->ifDeconfig = 1;
+        return 0;
 
     snprintf(buf, sizeof buf, "ip4:0.0.0.0,255.255.255.255;");
     log_line("%s: Resetting IP configuration.", client_config.interface);
-    ifchwrite(buf, strlen(buf));
+    ret = ifchwrite(buf, strlen(buf));
 
-    memset(&cfg_packet, 0, sizeof cfg_packet);
+    if (ret >= 0) {
+        cs->ifDeconfig = 1;
+        memset(&cfg_packet, 0, sizeof cfg_packet);
+    }
+    return ret;
 }
 
 static size_t send_client_ip(char out[static 1], size_t olen,
@@ -308,9 +312,6 @@ static size_t send_cmd(char out[static 1], size_t olen,
     uint8_t optdata[MAX_DOPT_SIZE], olddata[MAX_DOPT_SIZE];
     ssize_t optlen, oldlen;
 
-    if (!packet)
-        return 0;
-
     optlen = get_dhcp_opt(packet, code, optdata, sizeof optdata);
     if (!optlen)
         return 0;
@@ -321,14 +322,12 @@ static size_t send_cmd(char out[static 1], size_t olen,
     return r > 0 ? r : 0;
 }
 
-void ifchange_bind(struct client_state_t cs[static 1],
+int ifchange_bind(struct client_state_t cs[static 1],
                    struct dhcpmsg packet[static 1])
 {
     char buf[2048];
     size_t bo;
-
-    if (!packet)
-        return;
+    int ret = -1;
 
     memset(buf, 0, sizeof buf);
     bo = send_client_ip(buf, sizeof buf, packet);
@@ -339,8 +338,12 @@ void ifchange_bind(struct client_state_t cs[static 1],
     bo += send_cmd(buf + bo, sizeof buf - bo, packet, DCODE_MTU);
     bo += send_cmd(buf + bo, sizeof buf - bo, packet, DCODE_WINS);
     if (bo)
-        ifchwrite(buf, bo);
+        ret = ifchwrite(buf, bo);
 
-    cs->ifDeconfig = 0;
-    memcpy(&cfg_packet, packet, sizeof cfg_packet);
+    if (ret >= 0) {
+        cs->ifDeconfig = 0;
+        memcpy(&cfg_packet, packet, sizeof cfg_packet);
+    }
+    return ret;
 }
+
diff --git a/src/ifchange.h b/src/ifchange.h
index f3952b9..f3abc94 100644
--- a/src/ifchange.h
+++ b/src/ifchange.h
@@ -29,8 +29,8 @@
 #ifndef IFCHANGE_H_
 #define IFCHANGE_H_
 
-void ifchange_bind(struct client_state_t cs[static 1],
-                   struct dhcpmsg packet[static 1]);
-void ifchange_deconfig(struct client_state_t cs[static 1]);
+int ifchange_bind(struct client_state_t cs[static 1],
+                  struct dhcpmsg packet[static 1]);
+int ifchange_deconfig(struct client_state_t cs[static 1]);
 
 #endif
diff --git a/src/ndhc.c b/src/ndhc.c
index 0adb4bf..55fad76 100644
--- a/src/ndhc.c
+++ b/src/ndhc.c
@@ -74,7 +74,6 @@
 #include "rfkill.h"
 
 struct client_state_t cs = {
-    .ifDeconfig = 0,
     .init = 1,
     .epollFd = -1,
     .signalFd = -1,