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In build_{icmp,igmp}_raw, fill with zeros when data is NULL.

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This restores the previous behavior of these functions, which was broken
in r24127, which itself was fixing another bug.

r24127 solved the problem of --data-length appending zeroes, not random
data, to ICMP and IGMP packets. But in doing so, it added a check that
the data argument is not NULL. OS detection uses a data argument of
NULL, expecting these functions to fill in zeroes in this case. The
result of this was that the IE probes were being sent with empty
payloads instead of 120 and 150 bytes.
This commit is contained in:
david 2011-09-15 17:57:00 +00:00
parent 1c67d5e508
commit 8b01344caf
1 changed files with 10 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

15
tcpip.cc
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@ -1034,9 +1034,12 @@ u8 *build_icmp_raw(const struct in_addr *source,
}
/* Copy the data over too */
if (data && datalen) {
if (datalen > 0) {
icmplen += MIN(dlen, datalen);
memcpy(datastart, data, MIN(dlen, datalen));
if (data == NULL)
memset(datastart, 0, MIN(dlen, datalen));
else
memcpy(datastart, data, MIN(dlen, datalen));
}
/* Fill out the ping packet. All the ICMP types handled by this function have
@ -1140,10 +1143,12 @@ u8 *build_igmp_raw(const struct in_addr *source,
fatal("Unknown igmp type (%d) in %s", ptype, __func__);
}
/* Copy the data over too */
if (data && datalen) {
if (datalen > 0) {
igmplen += MIN(dlen, datalen);
memcpy(datastart, data, MIN(dlen, datalen));
if (data == NULL)
memset(datastart, 0, MIN(dlen, datalen));
else
memcpy(datastart, data, MIN(dlen, datalen));
}
igmp.igmp_cksum = 0;