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When verifying the IPv4 UDP checksum, don't overwrite the checksum

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value in the mbuf with the result of the calculation. Previously,
if we chose to return an ICMP message, the quoted UDP checksum bytes
would be different to what was sent.

PR:		112471
Submitted by:	Matthew Luckie <mluckie@cs.waikato.ac.nz>
MFC after:	3 weeks
This commit is contained in:
David Malone 2007-05-16 09:12:16 +00:00
parent 32cd239bbd
commit 39629c92cc
1 changed files with 7 additions and 5 deletions
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12
sys/netinet/udp_usrreq.c
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@ -250,24 +250,26 @@ udp_input(struct mbuf *m, int off)
* Checksum extended UDP header and data.
*/
if (uh->uh_sum) {
u_short uh_sum;
if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) {
if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR)
uh->uh_sum = m->m_pkthdr.csum_data;
uh_sum = m->m_pkthdr.csum_data;
else
uh->uh_sum = in_pseudo(ip->ip_src.s_addr,
uh_sum = in_pseudo(ip->ip_src.s_addr,
ip->ip_dst.s_addr, htonl((u_short)len +
m->m_pkthdr.csum_data + IPPROTO_UDP));
uh->uh_sum ^= 0xffff;
uh_sum ^= 0xffff;
} else {
char b[9];
bcopy(((struct ipovly *)ip)->ih_x1, b, 9);
bzero(((struct ipovly *)ip)->ih_x1, 9);
((struct ipovly *)ip)->ih_len = uh->uh_ulen;
uh->uh_sum = in_cksum(m, len + sizeof (struct ip));
uh_sum = in_cksum(m, len + sizeof (struct ip));
bcopy(b, ((struct ipovly *)ip)->ih_x1, 9);
}
if (uh->uh_sum) {
if (uh_sum) {
udpstat.udps_badsum++;
m_freem(m);
return;