From 5b78ef236e826f24fab4464094bd4cca0a3a502e Mon Sep 17 00:00:00 2001
From: dmiller <dmiller@e0a8ed71-7df4-0310-8962-fdc924857419>
Date: Tue, 10 Mar 2026 18:32:50 +0000
Subject: [PATCH] Gracefully handle arp_open failure

---
 nping/NpingTarget.cc | 21 +++++++++++++--------
 tcpip.cc             | 14 ++++++++------
 2 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/nping/NpingTarget.cc b/nping/NpingTarget.cc
index fee78246f..34abef648 100644
--- a/nping/NpingTarget.cc
+++ b/nping/NpingTarget.cc
@@ -769,16 +769,21 @@ bool NpingTarget::determineNextHopMACAddress() {
   /* Maybe the system ARP cache will be more helpful */
   nping_print(DBG_3,"    > Checking system's ARP cache...");
   a = arp_open();
-  addr_ston((sockaddr *)&targetss, &ae.arp_pa);
-  if (arp_get(a, &ae) == 0) {
-    mac_cache_set(&targetss, ae.arp_ha.addr_eth.data);
-    this->setNextHopMACAddress(ae.arp_ha.addr_eth.data);
+  if (a) {
+    addr_ston((sockaddr *)&targetss, &ae.arp_pa);
+    if (arp_get(a, &ae) == 0) {
+      mac_cache_set(&targetss, ae.arp_ha.addr_eth.data);
+      this->setNextHopMACAddress(ae.arp_ha.addr_eth.data);
+      arp_close(a);
+      nping_print(DBG_3,"    > Success: Entry found [%s]", this->getNextHopMACStr() );
+      return true;
+    }
     arp_close(a);
-    nping_print(DBG_3,"    > Success: Entry found [%s]", this->getNextHopMACStr() );
-    return true;
+    nping_print(DBG_3,"    > No relevant entries found in system's ARP cache.");
+  }
+  else {
+    nping_print(DBG_3,"    > Failed to open system's ARP cache.");
   }
-  arp_close(a);
-  nping_print(DBG_3,"    > No relevant entries found in system's ARP cache.");
 
 
   /* OK, the last choice is to send our own damn ARP request (and
diff --git a/tcpip.cc b/tcpip.cc
index 280a60be3..81243de1d 100644
--- a/tcpip.cc
+++ b/tcpip.cc
@@ -1663,14 +1663,16 @@ bool getNextHopMAC(const char *iface, const u8 *srcmac, const struct sockaddr_st
 
   /* Maybe the system ARP cache will be more helpful */
   a = arp_open();
-  addr_ston((sockaddr *) dstss, &ae.arp_pa);
-  if (arp_get(a, &ae) == 0) {
-    mac_cache_set(dstss, ae.arp_ha.addr_eth.data);
-    memcpy(dstmac, ae.arp_ha.addr_eth.data, 6);
+  if (a) {
+    addr_ston((sockaddr *) dstss, &ae.arp_pa);
+    if (arp_get(a, &ae) == 0) {
+      mac_cache_set(dstss, ae.arp_ha.addr_eth.data);
+      memcpy(dstmac, ae.arp_ha.addr_eth.data, 6);
+      arp_close(a);
+      return true;
+    }
     arp_close(a);
-    return true;
   }
-  arp_close(a);
 
   /* OK, the last choice is to send our own damn ARP request (and
      retransmissions if necessary) to determine the MAC */