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Revert TCP checksumming to cache common data, like it did before.

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This commit is contained in:
Jon Siwek 2012-03-29 14:41:44 -05:00
parent 877cc5b235
commit 7d7cadfb56
2 changed files with 11 additions and 10 deletions
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20
src/TCP_Endpoint.cc
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@ -31,6 +31,14 @@ TCP_Endpoint::TCP_Endpoint(TCP_Analyzer* arg_analyzer, int arg_is_orig)
tcp_analyzer->Conn()->OrigAddr();
dst_addr = is_orig ? tcp_analyzer->Conn()->OrigAddr() :
tcp_analyzer->Conn()->RespAddr();
checksum_base = ones_complement_checksum(src_addr, 0);
checksum_base = ones_complement_checksum(dst_addr, checksum_base);
// Note, for IPv6, strictly speaking this field is 32 bits
// rather than 16 bits. But because the upper bits are all zero,
// we get the same checksum either way. The same applies to
// later when we add in the data length in ValidChecksum().
checksum_base += htons(IPPROTO_TCP);
}
TCP_Endpoint::~TCP_Endpoint()
@ -100,21 +108,13 @@ void TCP_Endpoint::SizeBufferedData(int& waiting_on_hole, int& waiting_on_ack)
int TCP_Endpoint::ValidChecksum(const struct tcphdr* tp, int len) const
{
uint32 sum;
uint32 sum = checksum_base;
int tcp_len = tp->th_off * 4 + len;
if ( len % 2 == 1 )
// Add in pad byte.
sum = htons(((const u_char*) tp)[tcp_len - 1] << 8);
else
sum = 0;
sum += htons(((const u_char*) tp)[tcp_len - 1] << 8);
sum = ones_complement_checksum(src_addr, sum);
sum = ones_complement_checksum(dst_addr, sum);
// Note, for IPv6, strictly speaking the protocol and length fields are
// 32 bits rather than 16 bits. But because the upper bits are all zero,
// we get the same checksum either way.
sum += htons(IPPROTO_TCP);
sum += htons((unsigned short) tcp_len); // fill out pseudo header
sum = ones_complement_checksum((void*) tp, tcp_len, sum);

1
src/TCP_Endpoint.h
View file

@ -127,6 +127,7 @@ public:
TCP_Reassembler* contents_processor;
TCP_Analyzer* tcp_analyzer;
BroFile* contents_file;
uint32 checksum_base;
double start_time, last_time;
IPAddr src_addr; // the other endpoint