From a5baf9de0b449750127abbf88a2082668590d503 Mon Sep 17 00:00:00 2001
From: dmiller <dmiller@e0a8ed71-7df4-0310-8962-fdc924857419>
Date: Thu, 20 Jun 2024 20:14:31 +0000
Subject: [PATCH] Consolidate device name checking in nse_dnet.cc

---
 nse_dnet.cc | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/nse_dnet.cc b/nse_dnet.cc
index 73a323409..3514ac557 100644
--- a/nse_dnet.cc
+++ b/nse_dnet.cc
@@ -42,16 +42,31 @@ static int l_dnet_new (lua_State *L)
   lua_setmetatable(L, -2);
   udata->eth = NULL;
   udata->sock = -1;
+  udata->devname[0] = '\0';
 
   return 1;
 }
 
+static struct interface_info *checkdevname (lua_State *L, int idx)
+{
+  size_t len = 0;
+  const char *interface_name = luaL_checklstring(L, idx, &len);
+  if (len >= 32) {
+    luaL_argerror(L, idx, "device name too long");
+    return NULL;
+  }
+  struct interface_info *ii = getInterfaceByName(interface_name, o.af());
+  if (ii == NULL)
+    luaL_argerror(L, idx, "device %s not found or no address configured");
+
+  return ii;
+}
+
 static int l_dnet_get_interface_info (lua_State *L)
 {
   char ipstr[INET6_ADDRSTRLEN];
   struct addr src, bcast;
-  struct interface_info *ii = getInterfaceByName(luaL_checkstring(L, 1),
-                                                 o.af());
+  struct interface_info *ii = checkdevname(L, 1);
 
   if (ii == NULL)
     return nseU_safeerror(L, "failed to find interface");
@@ -150,11 +165,7 @@ static eth_t *open_eth_cached (lua_State *L, int dnet_index, const char *device)
 static int ethernet_open (lua_State *L)
 {
   nse_dnet_udata *udata = (nse_dnet_udata *) nseU_checkudata(L, 1, DNET_METATABLE, "dnet");
-  size_t len = 0;
-  const char *interface_name = luaL_checklstring(L, 2, &len);
-  if (len >= 32)
-    return luaL_argerror(L, 2, "device name too long");
-  struct interface_info *ii = getInterfaceByName(interface_name, o.af());
+  struct interface_info *ii = checkdevname(L, 2);
 
   if (ii == NULL || ii->device_type != devt_ethernet
 #ifdef WIN32
@@ -163,9 +174,9 @@ static int ethernet_open (lua_State *L)
     )
     return luaL_argerror(L, 2, "device is not valid ethernet interface");
 
-  udata->eth = open_eth_cached(L, 1, interface_name);
-  strncpy(udata->devname, interface_name, len);
-  udata->devname[len] = '\0';
+  udata->eth = open_eth_cached(L, 1, ii->devfullname);
+  strncpy(udata->devname, ii->devfullname, 16);
+  udata->devname[16] = '\0';
   if (o.scriptTrace())
   {
       log_write(LOG_STDOUT, "%s: Ethernet open %s\n",