Spicy: Provide zeek::skip_input() to disable deliver to current analyzer.

```
## Tells Zeek to skip sending any further input data to the current analyzer.
## This is supported for protocol and file analyzers.
public function skip_input() : void;
```

Closes #3443.

doc

@@ -1 +1 @@
-Subproject commit 278f7b7d0cda1aab5789122d808f411cd05a20fc
+Subproject commit 7d39602b09f16e1687408b63af3fd6a3edb33d07

scripts/spicy/zeek.spicy

@@ -118,6 +118,10 @@ public function fuid() : string &cxxname="zeek::spicy::rt::fuid";
 ## called from inside a protocol analyzer.
 public function terminate_session() : void &cxxname="zeek::spicy::rt::terminate_session";
 
+## Tells Zeek to skip sending any further input data to the current analyzer.
+## This is supported for protocol and file analyzers.
+public function skip_input() : void &cxxname="zeek::spicy::rt::skip_input";
+
 ## Signals the expected size of a file to Zeek's file analysis.
 ##
 ## size: expected size of file

src/spicy/runtime-support.cc

@@ -748,6 +748,19 @@ void rt::terminate_session() {
         throw spicy::rt::ValueUnavailable("terminate_session() not available in the current context");
 }
 
+void rt::skip_input() {
+    auto _ = hilti::rt::profiler::start("zeek/rt/skip_input");
+    auto cookie = static_cast<Cookie*>(hilti::rt::context::cookie());
+    assert(cookie);
+
+    if ( auto p = cookie->protocol )
+        p->analyzer->SetSkip(true);
+    else if ( auto f = cookie->file )
+        f->analyzer->SetSkip(true);
+    else
+        throw spicy::rt::ValueUnavailable("skip() not available in the current context");
+}
+
 std::string rt::fuid() {
     auto _ = hilti::rt::profiler::start("zeek/rt/fuid");
     auto cookie = static_cast<Cookie*>(hilti::rt::context::cookie());

src/spicy/runtime-support.h

@@ -381,7 +381,7 @@ void protocol_handle_close(const ProtocolHandle& handle);
  * Signals the beginning of a file to Zeek's file analysis, associating it
  * with the current connection.
  *
- * param mime_type optional mime type passed to Zeek
+ * @param mime_type optional mime type passed to Zeek
  * @returns Zeek-side file ID of the new file
  */
 std::string file_begin(const std::optional<std::string>& mime_type);
@@ -397,6 +397,12 @@ std::string fuid();
  */
 void terminate_session();
 
+/**
+ * Tells Zeek to skip sending any further input data to the current protocol
+ * or file analyzer.
+ */
+void skip_input();
+
 /**
  * Signals the expected size of a file to Zeek's file analysis.
  *

testing/btest/Baseline/spicy.skip-input-file/output

@@ -0,0 +1,4 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+1, 12
+2, 34
+3, 56

testing/btest/Baseline/spicy.skip-input-protocol/output

@@ -0,0 +1,7 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+1, True, 28
+event
+2, False, 256
+event
+3, True, 28
+event

testing/btest/spicy/skip-input-file.zeek

@@ -0,0 +1,60 @@
+# @TEST-REQUIRES: have-spicy
+#
+# @TEST-EXEC: spicyz -d -o test.hlto ssh.spicy ./ssh-cond.evt
+# @TEST-EXEC: zeek -r ${TRACES}/ssh/single-conn.trace test.hlto %INPUT Spicy::enable_print=T >output
+# @TEST-EXEC: btest-diff output
+#
+# @TEST-DOC: Validate that `skip_input` works for file analyzers.
+
+# @TEST-START-FILE ssh.spicy
+module SSH;
+
+import spicy;
+import zeek;
+
+public type Banner = unit {
+    magic   : /SSH-/;
+    version : /[^-]*/;
+    dash    : /-/;
+    software: /[^\r\n]*/;
+};
+
+type Context = tuple<counter: uint64>;
+
+public type Data = unit {
+    %context = Context;
+
+    : (bytes &size=2)[] foreach {
+        self.context().counter = self.context().counter + 1;
+
+        print self.context().counter, $$;
+
+        if ( self.context().counter == 3 )
+            zeek::skip_input();
+    }
+};
+
+on Banner::%done {
+    local fid1 = zeek::file_begin("foo/bar");
+    zeek::file_data_in(b"12", fid1);
+    zeek::file_data_in(b"34", fid1);
+    zeek::file_data_in(b"56", fid1);
+    zeek::file_data_in(b"78", fid1);
+    zeek::file_data_in(b"90", fid1);
+    zeek::file_end(fid1);
+}
+# @TEST-END-FILE
+
+# @TEST-START-FILE ssh-cond.evt
+
+import zeek;
+
+protocol analyzer spicy::SSH over TCP:
+    parse originator with SSH::Banner,
+    port 22/tcp,
+    replaces SSH;
+
+file analyzer spicy::Text:
+    parse with SSH::Data,
+    mime-type foo/bar;
+# @TEST-END-FILE

testing/btest/spicy/skip-input-protocol.zeek

@@ -0,0 +1,44 @@
+# @TEST-REQUIRES: have-spicy
+#
+# @TEST-EXEC: spicyz -d -o test.hlto test.spicy test.evt
+# @TEST-EXEC: zeek -b -r ${TRACES}/dns/long-connection.pcap Zeek::Spicy test.hlto %INPUT "Spicy::enable_print = T;" >output
+# @TEST-EXEC: btest-diff output
+#
+# @TEST-DOC: Validate that `skip_input` works for protocol analyzers.
+
+redef likely_server_ports += { 53/udp }; # avoid flipping direction after termination
+redef udp_inactivity_timeout = 24hrs; # avoid long gaps to trigger removal
+
+event Test::foo() { print "event"; }
+
+# @TEST-START-FILE test.spicy
+module Test;
+
+import zeek;
+
+type Counter = tuple<counter: int64>;
+
+public type Foo = unit {
+    %context = Counter;
+
+    data: bytes &eod;
+
+    on %done {
+        self.context().counter = self.context().counter + 1;
+
+        print self.context().counter, zeek::is_orig(), |self.data|;
+
+        if ( self.context().counter == 3 )
+            zeek::skip_input();
+    }
+};
+
+# @TEST-END-FILE
+
+# @TEST-START-FILE test.evt
+protocol analyzer spicy::Test over UDP:
+    port 53/udp,
+    parse with Test::Foo;
+
+on Test::Foo -> event Test::foo();
+# @TEST-END-FILE