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Make in_delayed_cksum() be similar to IPv6 implementation.

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Use m_copyback() function to write checksum when it isn't located
in the first mbuf of the chain. Handmade analog doesn't handle the
case when parts of checksum are located in different mbufs.
Also in case when mbuf is too short, m_copyback() will allocate new
mbuf in the chain instead of making out of bounds write.

Also wrap long line and remove now useless KASSERTs.

X-MFC after:	r334705
This commit is contained in:
Andrey V. Elsukov 2018-06-06 13:01:53 +00:00
parent 32c369f40c
commit 590d0a43b6
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=334709
1 changed files with 7 additions and 11 deletions
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18
sys/netinet/ip_output.c
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@ -933,10 +933,10 @@ in_delayed_cksum(struct mbuf *m)
if (m->m_pkthdr.csum_flags & CSUM_UDP) {
/* if udp header is not in the first mbuf copy udplen */
if (offset + sizeof(struct udphdr) > m->m_len)
m_copydata(m, offset + offsetof(struct udphdr, uh_ulen),
2, (caddr_t)&cklen);
m_copydata(m, offset + offsetof(struct udphdr,
uh_ulen), sizeof(cklen), (caddr_t)&cklen);
else {
uh = (struct udphdr *)((caddr_t)ip + offset);
uh = (struct udphdr *)mtodo(m, offset);
cklen = ntohs(uh->uh_ulen);
}
csum = in_cksum_skip(m, cklen + offset, offset);
@ -948,14 +948,10 @@ in_delayed_cksum(struct mbuf *m)
}
offset += m->m_pkthdr.csum_data; /* checksum offset */
/* find the mbuf in the chain where the checksum starts*/
while ((m != NULL) && (offset >= m->m_len)) {
offset -= m->m_len;
m = m->m_next;
}
KASSERT(m != NULL, ("in_delayed_cksum: checksum outside mbuf chain."));
KASSERT(offset + sizeof(u_short) <= m->m_len, ("in_delayed_cksum: checksum split between mbufs."));
*(u_short *)(m->m_data + offset) = csum;
if (offset + sizeof(csum) > m->m_len)
m_copyback(m, offset, sizeof(csum), (caddr_t)&csum);
else
*(u_short *)mtodo(m, offset) = csum;
}
/*