Check if interface is null before starting sequence.

src/sequence.c

@@ -711,10 +711,18 @@ void *thread_hdl(void *temp)
 **/
 void seq_send(const char *interface, sequence_t seq, u16 seq_cnt2, cmd_line_t cmd)
 {
- // First, let's check if the destination IP is set.
+ // First, make sure interface isn't NULL.
+ if (interface == NULL)
+ {
+ fprintf(stderr, "Interface not set on sequence #%d. Not moving forward with this sequence.\n", seq_cnt2);
+
+ return;
+ }
+
+ // Let's check if the destination IP is set.
  if (seq.ip.dst_ip == NULL)
  {
- fprintf(stdout, "Destination IP not set on sequence #%u. Not moving forward with this sequence.\n", seq_cnt2);
+ fprintf(stderr, "Destination IP not set on sequence #%d. Not moving forward with this sequence.\n", seq_cnt2);
 
  return;
  }