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ip: exclude "don't fragment" bit from ipv4 reassembly test

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other operating systems always set the "don't fragment" bit
in ther outgoing ipv4 packets causing us to unnecesarily
call ip4reassemble() looking for a fragment reassembly queue.

the change excludes the "don't fragment" bit from the test
so we now call ip4reassemble() only when the "more fragmens"
bit is set or a fragment offset other than zero is given.

this optimization was discovered from akaros.
This commit is contained in:
cinap_lenrek 2014-12-21 17:25:55 +01:00
parent bf049ebdb1
commit 1db9f19b62
1 changed files with 2 additions and 2 deletions
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4
sys/src/9/ip/ip.c
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@ -405,7 +405,7 @@ ipiput4(Fs *f, Ipifc *ifc, Block *bp)
if(r->ifc == nil) panic("nil route rfc"); if(r->ifc == nil) panic("nil route rfc");
if(r->ifc->reassemble){ if(r->ifc->reassemble){
frag = nhgets(h->frag); frag = nhgets(h->frag);
if(frag) { if(frag & ~IP_DF) {
h->tos = 0; h->tos = 0;
if(frag & IP_MF) if(frag & IP_MF)
h->tos = 1; h->tos = 1;
@ -424,7 +424,7 @@ if(r->ifc == nil) panic("nil route rfc");
} }
frag = nhgets(h->frag); frag = nhgets(h->frag);
if(frag) { if(frag & ~IP_DF) {
h->tos = 0; h->tos = 0;
if(frag & IP_MF) if(frag & IP_MF)
h->tos = 1; h->tos = 1;