1 files changed, 28 insertions, 17 deletions
diff --git a/cmake/external/grpc.cmake b/cmake/external/grpc.cmake
index ee4d246..a789838 100644
--- a/cmake/external/grpc.cmake
+++ b/cmake/external/grpc.cmake
@@ -14,7 +14,6 @@
 
 include(ExternalProject)
 include(ExternalProjectFlags)
-include(FindZLIB)
 
 if(GRPC_ROOT)
   # If the user has supplied a GRPC_ROOT then just use it. Add an empty custom
@@ -25,7 +24,6 @@ else()
   set(
     GIT_SUBMODULES
     third_party/boringssl
-    third_party/cares/cares
   )
 
   set(
@@ -47,44 +45,55 @@ else()
   )
 
 
+  ## c-ares
+  if(NOT c-ares_DIR)
+    set(c-ares_DIR ${FIREBASE_INSTALL_DIR}/lib/cmake/c-ares)
+  endif()
+
+  list(
+    APPEND CMAKE_ARGS
+    -DgRPC_CARES_PROVIDER:STRING=package
+    -Dc-ares_DIR:PATH=${c-ares_DIR}
+  )
+
+
   ## protobuf
 
   # Unlike other dependencies of gRPC, we control the protobuf version because we
   # have checked-in protoc outputs that must match the runtime.
 
   # The location where protobuf-config.cmake will be installed varies by platform
-  if (WIN32)
-    set(PROTOBUF_CMAKE_DIR "${FIREBASE_INSTALL_DIR}/cmake")
-  else()
-    set(PROTOBUF_CMAKE_DIR "${FIREBASE_INSTALL_DIR}/lib/cmake/protobuf")
+  if(NOT Protobuf_DIR)
+    if(WIN32)
+      set(Protobuf_DIR "${FIREBASE_INSTALL_DIR}/cmake")
+    else()
+      set(Protobuf_DIR "${FIREBASE_INSTALL_DIR}/lib/cmake/protobuf")
+    endif()
   endif()
 
   list(
     APPEND CMAKE_ARGS
     -DgRPC_PROTOBUF_PROVIDER:STRING=package
     -DgRPC_PROTOBUF_PACKAGE_TYPE:STRING=CONFIG
-    -DProtobuf_DIR:PATH=${PROTOBUF_CMAKE_DIR}
+    -DProtobuf_DIR:PATH=${Protobuf_DIR}
   )
 
 
   ## zlib
 
-  # zlib can be built by grpc but we can avoid it on platforms that provide it
-  # by default.
-  find_package(ZLIB)
+  # cmake/external/zlib.cmake figures out whether or not to build zlib. Either
+  # way, from the gRPC build's point of view it's a package.
+  list(
+    APPEND CMAKE_ARGS
+    -DgRPC_ZLIB_PROVIDER:STRING=package
+  )
   if(ZLIB_FOUND)
+    # Propagate possible user configuration to FindZLIB.cmake in the sub-build.
     list(
       APPEND CMAKE_ARGS
-      -DgRPC_ZLIB_PROVIDER:STRING=package
       -DZLIB_INCLUDE_DIR=${ZLIB_INCLUDE_DIR}
       -DZLIB_LIBRARY=${ZLIB_LIBRARY}
     )
-
-  else()
-    list(
-      APPEND GIT_SUBMODULES
-      third_party/zlib
-    )
   endif()
 
 
@@ -98,7 +107,9 @@ else()
   ExternalProject_Add(
     grpc
     DEPENDS
+      c-ares
       protobuf
+      zlib
 
     ${GRPC_GIT}