[PATCH] Make new UDP-payload code reusable.

["Luis M." <luis.mgarc () gmail com>]

Hi!

I've been having a look at David's new UDP-payload code and I've seen
that it depends on the NmapOps class so the code is not reusable by
other apps. The thing is that at some point I would like to include that
functionality to nping. For that, the best thing would be to move
UDP-payload-related code to nbase (same thing Fyodor and I are planning
to do with many other functions that nmap and nping share).

So the thing is that function get_udp_payload() has this:

const char *get_udp_payload(u16 dport, size_t *length) {
  const char *payload;

  if (o.extra_payload_length > 0) {
    *length = o.extra_payload_length;
    return o.extra_payload;
  }

In my opinion, it should be the caller's responsibility to ensure that
the user has not specified a custom payload. I've checked which parts of
nmap actually call get_udp_payload() and I've found that only
sendIPScanProbe() uses it. Moving that if sentence to sendIPScanProbe()
is trivial and should make get_udp_payload() reusable by other apps so
we can move it to nbase at some point.

I attach a patch that does this. Please let me know what you think. Is
there any important disadvantage to my approach?

Regards,


Luis.

Index: scan_engine.cc
===================================================================
--- scan_engine.cc      (revision 14088)
+++ scan_engine.cc      (working copy)
@@ -3089,9 +3089,15 @@
   } else if (pspec->type == PS_UDP) {
     const char *payload;
     size_t payload_length;
-
-    payload = get_udp_payload(pspec->pd.udp.dport, &payload_length);
-
+    
+    /* If user requested a specific payload, use it. Otherwise use our own
+     * UDP payload (the scan may get better results this way) */
+    if (o.extra_payload_length > 0) {
+        payload_length = o.extra_payload_length;
+        payload = o.extra_payload;
+    }else{
+        payload = get_udp_payload(pspec->pd.udp.dport, &payload_length);
+    }
     for(decoy = 0; decoy < o.numdecoys; decoy++) {
       packet = build_udp_raw(&o.decoys[decoy], hss->target->v4hostip(),
                             o.ttl, ipid, IP_TOS_DEFAULT, false,
Index: payload.cc
===================================================================
--- payload.cc  (revision 14088)
+++ payload.cc  (working copy)
@@ -138,11 +138,6 @@
 const char *get_udp_payload(u16 dport, size_t *length) {
   const char *payload;
 
-  if (o.extra_payload_length > 0) {
-    *length = o.extra_payload_length;
-    return o.extra_payload;
-  }
-
 #define SET_PAYLOAD(p) do { *length = sizeof(p) - 1; payload = (p); } while (0)
 
   switch (dport) {


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