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Suppress Teredo weirds unless decapsulation was successful once before.

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This commit is contained in:
Jon Siwek 2012-06-04 16:57:46 -05:00
parent 9851591317
commit ae85bd1b95
3 changed files with 39 additions and 20 deletions
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5
src/Analyzer.h
View file

@ -215,6 +215,11 @@ public:
// analyzer, even if the method is called multiple times.
virtual void ProtocolConfirmation();
// Return whether the analyzer previously called ProtocolConfirmation()
// at least once before.
virtual bool ProtocolConfirmed() const
{ return protocol_confirmed; }
// Report that we found a significant protocol violation which might
// indicate that the analyzed data is in fact not the expected
// protocol. The protocol_violation event is raised once per call to

34
src/Teredo.cc
View file

@ -13,7 +13,8 @@ bool TeredoEncapsulation::DoParse(const u_char* data, int& len,
{
if ( len < 2 )
{
reporter->Weird(conn, "truncated_Teredo");
Weird("truncated_Teredo");
return false;
}
uint16 tag = ntohs((*((const uint16*)data)));
@ -27,7 +28,7 @@ bool TeredoEncapsulation::DoParse(const u_char* data, int& len,
if ( len < 8 )
{
reporter->Weird(conn, "truncated_Teredo_origin_indication");
Weird("truncated_Teredo_origin_indication");
return false;
}
@ -46,7 +47,7 @@ bool TeredoEncapsulation::DoParse(const u_char* data, int& len,
if ( len < 4 )
{
reporter->Weird(conn, "truncated_Teredo_authentication");
Weird("truncated_Teredo_authentication");
return false;
}
@ -56,7 +57,7 @@ bool TeredoEncapsulation::DoParse(const u_char* data, int& len,
if ( len < tot_len )
{
reporter->Weird(conn, "truncated_Teredo_authentication");
Weird("truncated_Teredo_authentication");
return false;
}
@ -70,13 +71,13 @@ bool TeredoEncapsulation::DoParse(const u_char* data, int& len,
// IPv6
if ( len < 40 )
{
reporter->Weird(conn, "truncated_IPv6_in_Teredo");
Weird("truncated_IPv6_in_Teredo");
return false;
}
if ( len - 40 != ntohs(((const struct ip6_hdr*)data)->ip6_plen) )
{
reporter->Weird(conn, "Teredo_payload_len_mismatch");
Weird("Teredo_payload_len_mismatch");
return false;
}
@ -92,25 +93,24 @@ void Teredo_Analyzer::DeliverPacket(int len, const u_char* data, bool orig,
{
Analyzer::DeliverPacket(len, data, orig, seq, ip, caplen);
const Encapsulation* e = Conn()->GetEncapsulation();
if ( e && e->Depth() >= BifConst::Tunnel::max_depth )
{
reporter->Weird(Conn(), "tunnel_depth");
return;
}
TeredoEncapsulation te(Conn());
TeredoEncapsulation te(this);
if ( ! te.Parse(data, len) )
{
ProtocolViolation("Invalid Teredo encapsulation", (const char*)data,
len);
ProtocolViolation("Bad Teredo encapsulation", (const char*)data, len);
return;
}
ProtocolConfirmation();
const Encapsulation* e = Conn()->GetEncapsulation();
if ( e && e->Depth() >= BifConst::Tunnel::max_depth )
{
Weird("tunnel_depth");
return;
}
// TODO: raise Teredo-specific events
Encapsulation* outer = new Encapsulation(e);

20
src/Teredo.h
View file

@ -24,6 +24,17 @@ public:
//TODO: specific option to turn off Teredo analysis?
{ return BifConst::Tunnel::max_depth > 0; }
/**
* Emits a weird only if the analyzer has previously been able to
* decapsulate a Teredo packet since otherwise the weirds could happen
* frequently enough to be less than helpful.
*/
void Weird(const char* name) const
{
if ( ProtocolConfirmed() )
reporter->Weird(Conn(), name);
}
protected:
friend class AnalyzerTimer;
void ExpireTimer(double t);
@ -31,8 +42,8 @@ protected:
class TeredoEncapsulation {
public:
TeredoEncapsulation(Connection* c)
: inner_ip(0), origin_indication(0), auth(0), conn(c)
TeredoEncapsulation(const Teredo_Analyzer* ta)
: inner_ip(0), origin_indication(0), auth(0), analyzer(ta)
{}
/**
@ -54,10 +65,13 @@ public:
protected:
bool DoParse(const u_char* data, int& len, bool found_orig, bool found_au);
void Weird(const char* name) const
{ analyzer->Weird(name); }
const u_char* inner_ip;
const u_char* origin_indication;
const u_char* auth;
Connection* conn;
const Teredo_Analyzer* analyzer;
};
#endif