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Don't use htons to unconditionally swap bytes.

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htons is a no-op on big-endian architectures. This affected idle scan IP
ID computations.

http://seclists.org/nmap-dev/2013/q2/529
This commit is contained in:
david
2013-06-30 02:22:13 +00:00
parent 9e82bb6c4e
commit af8c57a1b8
2 changed files with 9 additions and 2 deletions
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7
idle_scan.cc
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@@ -237,6 +237,9 @@ static int ipid_proxy_probe(struct idle_proxy_info *proxy, int *probes_sent,
return ipid;
}
static u16 byteswap_u16(u16 h) {
return ((h&0xff) << 8) | ((h>>8)&0xff);
}
/* Returns the number of increments between an early IP ID and a later
one, assuming the given IP ID Sequencing class. Returns -1 if the
@@ -248,8 +251,8 @@ static int ipid_distance(int seqclass , u16 startid, u16 endid) {
if (seqclass == IPID_SEQ_BROKEN_INCR) {
/* Convert to network byte order */
startid = htons(startid);
endid = htons(endid);
startid = byteswap_u16(startid);
endid = byteswap_u16(endid);
return endid - startid;
}