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9b0d525728
Conceptually, a TCP-based application analyzer should not need any knowledge about the underlying TCP analysis; it's supposed to just process its reassembled input stream as it's handed over. But our analyzers break that assumption at a few places because sometimes knowledge about the TCP state of the connection can be helpful for heuristics. This is fine as long as there actually *is* a TCP parent analyzer available. Sometimes, however, there isn't: if the payload stream is encapsulated inside another application-layer protocol, the semantic link to TCP is broken. And if the outer connection is even UDP, then we don't have a TCP analyzer at all. We didn't handle this situation well so far. Most analyzers needing TCP state would just crash if there's no TCP analyzer (in debug mode with an `assert`, in release mode with a null pointer deref ...). Only HTTP did the right thing already: check if TCP is available and adapt accordingly. We know extend that check to all other analyzers as well: all accesses to `TCP()` are guarded, with reasonable defaults if not available. It's actually a pretty small change overall, which is evidence for how little this layering violation actually matters. The existing behavior is what's causing https://github.com/corelight/zeek-spicy-openvpn/issues/3.
65 lines
1.4 KiB
C++
65 lines
1.4 KiB
C++
#include "FOO.h"
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#include "zeek/analyzer/protocol/tcp/TCP_Reassembler.h"
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#include "zeek/Reporter.h"
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#include "foo.bif.h"
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using namespace btest::analyzer::FOO;
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using namespace zeek::analyzer;
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FOO_Analyzer::FOO_Analyzer(zeek::Connection* c) : tcp::TCP_ApplicationAnalyzer("FOO", c)
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{
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interp = new binpac::FOO::FOO_Conn(this);
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had_gap = false;
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}
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FOO_Analyzer::~FOO_Analyzer()
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{
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delete interp;
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}
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void FOO_Analyzer::Done()
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{
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tcp::TCP_ApplicationAnalyzer::Done();
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interp->FlowEOF(true);
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interp->FlowEOF(false);
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}
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void FOO_Analyzer::EndpointEOF(bool is_orig)
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{
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tcp::TCP_ApplicationAnalyzer::EndpointEOF(is_orig);
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interp->FlowEOF(is_orig);
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}
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void FOO_Analyzer::DeliverStream(int len, const u_char* data, bool orig)
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{
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tcp::TCP_ApplicationAnalyzer::DeliverStream(len, data, orig);
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if ( TCP() && TCP()->IsPartial() )
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return;
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if ( had_gap )
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// If only one side had a content gap, we could still try to
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// deliver data to the other side if the script layer can handle this.
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return;
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try
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{
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interp->NewData(orig, data, data + len);
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}
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catch ( const binpac::Exception& e )
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{
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printf("Exception: %s\n", e.c_msg());
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ProtocolViolation(zeek::util::fmt("Binpac exception: %s", e.c_msg()));
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}
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}
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void FOO_Analyzer::Undelivered(uint64_t seq, int len, bool orig)
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{
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tcp::TCP_ApplicationAnalyzer::Undelivered(seq, len, orig);
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had_gap = true;
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interp->NewGap(orig, len);
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}
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