--- embedaddon/arping/src/unix.c	2016/10/18 13:16:10	1.1.1.2
+++ embedaddon/arping/src/unix.c	2021/03/16 23:40:57	1.1.1.3
@@ -20,19 +20,83 @@
 #include "config.h"
 #endif
 
+#include <errno.h>
 #include <signal.h>
+#include <string.h>
 
+#if HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+
+#if HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+
 #include <pcap.h>
 
 #include "arping.h"
 
+#define UNUSED(x) (void)(x)
+
 /**
  * Fall back on getting device name from pcap.
  */
 const char *
 arping_lookupdev_default(uint32_t srcip, uint32_t dstip, char *ebuf)
 {
+#ifdef HAVE_PCAP_FINDALLDEVS
+        UNUSED(srcip);
+        pcap_if_t *ifs = NULL;
+        int rc = pcap_findalldevs(&ifs, ebuf);
+        if (rc) {
+                return NULL;
+        }
+
+        pcap_if_t *t;
+        char* ifname = NULL;
+        for (t = ifs; !ifname && t; t = t->next) {
+#ifdef PCAP_IF_LOOPBACK
+                if (t->flags & PCAP_IF_LOOPBACK) {
+                        continue;
+                }
+#endif
+#ifdef PCAP_IF_UP
+                if (!(t->flags & PCAP_IF_UP)) {
+                        continue;
+                }
+#endif
+
+                // This code is only called when using -F, which is "don't try
+                // to be smart". If we wanted to be smart we would have used
+                // findif_*.c.
+                if (1) {
+                        ifname = strdup(t->name); // Memory leak.
+                        break;
+                }
+
+                // UNREACHABLE
+                pcap_addr_t *a;
+                for (a = t->addresses; !ifname && a; a = a->next) {
+                        if (a->addr->sa_family != AF_INET) {
+                                continue;
+                        }
+                        const struct sockaddr_in* sa = (struct sockaddr_in*)a->addr;
+                        const struct sockaddr_in* smask = (struct sockaddr_in*)a->netmask;
+                        const uint32_t addr = sa->sin_addr.s_addr;
+                        const uint32_t mask = smask->sin_addr.s_addr;
+                        if ((addr & mask) != (dstip & mask)) {
+                                // Not optimal: memory leak.
+                                ifname = strdup(t->name);
+                        }
+                }
+        }
+        pcap_freealldevs(ifs);
+        return ifname;
+#else
+        UNUSED(srcip);
+        UNUSED(dstip);
         return pcap_lookupdev(ebuf);
+#endif
 }
 
 /**
@@ -41,7 +105,10 @@ arping_lookupdev_default(uint32_t srcip, uint32_t dsti
 void
 do_signal_init()
 {
-        signal(SIGINT, sigint);
+        if (SIG_ERR == signal(SIGINT, sigint)) {
+                fprintf(stderr, "arping: failed to set SIGINT handler: %s\n",
+                        strerror(errno));
+        }
 }
 /* ---- Emacs Variables ----
  * Local Variables: