[WIP] Add support for barriers

.cirrus.yml

@@ -10,7 +10,7 @@ environment:
     HILTI_CXX_COMPILER_LAUNCHER: ccache
 
     # Spicy branch to download artifact from.
-    SPICY_BRANCH: main
+    SPICY_BRANCH: topic/robin/gh-1328-barrier
 
 zkg_task:
   timeout_in: 120m

src/plugin/protocol-analyzer.cc

@@ -41,6 +41,7 @@ void ProtocolAnalyzer::Done() {}
 
 void ProtocolAnalyzer::Process(bool is_orig, int len, const u_char* data) {
     auto* endp = is_orig ? &_originator : &_responder;
+    auto* other_endp = is_orig ? &_responder : &_originator;
 
     if ( endp->cookie().analyzer->Skipping() )
         return;
@@ -63,6 +64,12 @@ void ProtocolAnalyzer::Process(bool is_orig, int len, const u_char* data) {
     try {
         hilti::rt::context::CookieSetter _(&endp->cookie());
         endp->process(len, reinterpret_cast<const char*>(data));
+
+        if ( other_endp->isWaitingAtBarrier() )
+            // Give the other side a chance to see if the barrier is now
+            // cleared.
+            other_endp->process(0, "");
+
     } catch ( const hilti::rt::RuntimeError& e ) {
         STATE_DEBUG_MSG(is_orig, hilti::rt::fmt("error during parsing, triggering analyzer violation: %s", e.what()));
         auto tag = OurPlugin->tagForProtocolAnalyzer(endp->cookie().analyzer->GetAnalyzerTag());

tests/Baseline/zeek.barrier/output

@@ -0,0 +1,9 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+I am Hans.
+Hello Hans.
+I am Paula.
+Hello Paula.
+I am Peter.
+Hello Peter.
+I am Hanna.
+Hello Hanna.

tests/Traces/README

@@ -2,6 +2,7 @@
 Our PCAPs:
     - ssh-single-conn.trace
     - udp.trace
+    - barrier.pcap
 
 Sources for external PCAPs:
 

tests/barrier.evt

@@ -0,0 +1,6 @@
+import zeek;
+
+protocol analyzer spicy::Test over TCP:
+    parse originator with Test::Requests,
+    parse responder with Test::Replies,
+    port 12345/tcp;

tests/zeek/barrier.spicy

@@ -0,0 +1,68 @@
+# @TEST-EXEC: spicyz -o test.hlto %INPUT barrier.evt
+# @TEST-EXEC: zeek -b -Cr ${TRACES}/barrier.pcap Zeek::Spicy test.hlto Spicy::enable_print=T >output
+# @TEST-EXEC: btest-diff output
+#
+# @TEST-DOC: Use barriers to model a protocol where request/response pairs need to be processed in lock step.
+
+module Test;
+
+type Context = struct {
+    request: barrier(1);
+    reply: barrier(1);
+};
+
+public type Requests = unit {
+    %context = Context;
+
+    on %init {
+        self.context().reply.arrive();
+    }
+
+    : (Request(self.context()))[];
+};
+
+type Request = unit(ctx: Context&) {
+    on %init {
+        ctx.reply.wait();
+        ctx.reply.reset();
+    }
+
+    /[^\n]+\n/ { print $$.strip(); }
+
+    on %done {
+        ctx.request.arrive();
+    }
+
+};
+
+public type Replies = unit {
+    %context = Context;
+
+    : (Reply(self.context()))[];
+};
+
+type Reply = unit(ctx: Context&) {
+    on %init {
+        ctx.request.wait();
+        ctx.request.reset();
+    }
+
+    /[^\n]+\n/ { print $$.strip(); }
+
+    on %done {
+        ctx.reply.arrive();
+    }
+
+};
+
+
+@TEST-START-FILE barrier.evt
+
+import zeek;
+
+protocol analyzer spicy::Test over TCP:
+    parse originator with Test::Requests,
+    parse responder with Test::Replies,
+    port 12345/tcp;
+
+@TEST-END-FILE