Enable building ZeroMQ support on Windows

ci/windows/build.cmd

@@ -7,5 +7,5 @@ call "c:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools\VC\Auxiliar
 mkdir build
 cd build
 
-cmake.exe .. -DCMAKE_BUILD_TYPE=release -DVCPKG_TARGET_TRIPLET="x64-windows-static" -DENABLE_ZEEK_UNIT_TESTS=yes -DENABLE_CLUSTER_BACKEND_ZEROMQ=no -G Ninja
+cmake.exe .. -DCMAKE_BUILD_TYPE=release -DVCPKG_TARGET_TRIPLET="x64-windows-static" -DENABLE_ZEEK_UNIT_TESTS=yes -G Ninja
 cmake.exe --build .

src/cluster/backend/CMakeLists.txt

@@ -1,7 +1,3 @@
-list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/zeromq/cmake")
-
-find_package(ZeroMQ)
-
 # Default to building ZeroMQ only if ZeroMQ was found.
 #
 # If a user enabled the cluster backend explicitly (-D ENABLE_CLUSTER_BACKEND_ZEROMQ:bool=ON),
@@ -9,6 +5,14 @@ find_package(ZeroMQ)
 option(ENABLE_CLUSTER_BACKEND_ZEROMQ "Enable the ZeroMQ cluster backend" ON)
 
 if (ENABLE_CLUSTER_BACKEND_ZEROMQ)
+
+    if (MSVC)
+        find_package(ZeroMQ CONFIG REQUIRED)
+    else ()
+        list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/zeromq/cmake")
+        find_package(ZeroMQ REQUIRED)
+    endif ()
+
     if (NOT ZeroMQ_FOUND)
         message(FATAL_ERROR "ENABLE_CLUSTER_BACKEND_ZEROMQ set, but ZeroMQ library not available")
     endif ()

src/cluster/backend/zeromq/CMakeLists.txt

@@ -1,6 +1,8 @@
-list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
-
-find_package(ZeroMQ REQUIRED)
+# On MSVC, ZeroMQ_LIBRARIES may not be set by find_package() earlier in the
+# process. If it isn't, set it to the static target generated by vcpkg.
+if (MSVC AND NOT ZeroMQ_LIBRARIES)
+    set(ZeroMQ_LIBRARIES libzmq-static)
+endif ()
 
 zeek_add_plugin(
     Zeek Cluster_Backend_ZeroMQ

vcpkg.json

@@ -3,7 +3,9 @@
   "version-string": "latest",
   "dependencies": [
     "c-ares",
+    "cppzmq",
     "libpcap",
+    "zeromq",
     "zlib"
   ]
 }