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Always quote the entire TCP header when responding and allocate an mbuf

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cluster if needed.

Fixes the TCP issues raised in I-D draft-gont-icmp-payload-00.txt.

This aids in-the-wild debugging a lot and allows the receiver to do
more elaborate checks on the validity of the response.

MFC after:	2 weeks
Sponsored by:	TCP/IP Optimization Fundraise 2005
This commit is contained in:
Andre Oppermann 2005-08-22 14:12:18 +00:00
parent d56ea155bd
commit 6b773dff30
1 changed files with 24 additions and 4 deletions
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28
sys/netinet/ip_icmp.c
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@ -183,7 +183,7 @@ icmp_error(n, type, code, dest, mtu)
/*
* First, formulate icmp message
*/
m = m_gethdr(M_DONTWAIT, MT_HEADER);
MGETHDR(m, M_DONTWAIT, MT_HEADER);
if (m == NULL)
goto freeit;
#ifdef MAC
@ -193,11 +193,31 @@ icmp_error(n, type, code, dest, mtu)
* Calculate length to quote from original packet and
* prevent the ICMP mbuf from overflowing.
*/
icmplen = min(oiplen + max(8, icmp_quotelen), oip->ip_len);
icmplen = min(icmplen, M_TRAILINGSPACE(m) -
(ICMP_MINLEN + sizeof(struct ip)));
if (oip->ip_p == IPPROTO_TCP) {
struct tcphdr *th;
int tcphlen;
if (n->m_len < oiplen + sizeof(struct tcphdr) &&
((n = m_pullup(n, oiplen + sizeof(struct tcphdr))) == NULL))
goto freeit;
th = (struct tcphdr *)((caddr_t)oip + oiplen);
tcphlen = th->th_off << 2;
if (tcphlen < sizeof(struct tcphdr))
goto freeit;
if (oip->ip_len < oiplen + tcphlen)
goto freeit;
if (n->m_len < oiplen + tcphlen &&
((n = m_pullup(n, oiplen + tcphlen)) == NULL))
goto freeit;
icmplen = max(oiplen + tcphlen, min(icmp_quotelen, oip->ip_len));
} else
icmplen = min(oiplen + max(8, icmp_quotelen), oip->ip_len);
if (icmplen < sizeof(struct ip))
panic("icmp_error: bad length");
if (icmplen + ICMP_MINLEN + sizeof(struct ip) > MHLEN)
MCLGET(m, M_DONTWAIT);
if (!(m->m_flags & M_EXT))
goto freeit;
m->m_len = icmplen + ICMP_MINLEN;
MH_ALIGN(m, m->m_len);
icp = mtod(m, struct icmp *);