feat(NODE-5746): allow runtime linking against system kerberos library (#165)

Author: addaleax

.evergreen/config.yml

@@ -67,6 +67,8 @@ functions:
         env:
           PROJECT_DIRECTORY: ${PROJECT_DIRECTORY}
           PROJECT: ${project}
+          GYP_DEFINES: ${GYP_DEFINES|}
+          NPM_OPTIONS: ${NPM_OPTIONS|}
         args:
           - run
           - '--interactive'
@@ -76,6 +78,10 @@ functions:
           - /app
           - '--env'
           - PROJECT_DIRECTORY=/app
+          - '--env'
+          - GYP_DEFINES
+          - '--env'
+          - NPM_OPTIONS
           - 'ubuntu:22.04'
           - /bin/bash
           - /app/.evergreen/run-tests-ubuntu.sh
@@ -122,6 +128,12 @@ tasks:
   - name: run-tests-ubuntu
     commands:
       - func: run tests ubuntu
+  - name: run-tests-ubuntu-rtld
+    commands:
+      - func: run tests ubuntu
+        vars:
+          GYP_DEFINES: kerberos_use_rtld=true
+          NPM_OPTIONS: --build-from-source
   - name: run-prebuild
     commands:
       - func: install dependencies
@@ -194,6 +206,7 @@ buildvariants:
       packager_arch: x86_64
     tasks:
       - run-tests-ubuntu
+      - run-tests-ubuntu-rtld
   - name: ubuntu2204-arm64
     display_name: 'Ubuntu 22.04 arm64'
     run_on: ubuntu2204-arm64-small
@@ -203,3 +216,4 @@ buildvariants:
       packager_arch: arm64
     tasks:
       - run-tests-ubuntu
+      - run-tests-ubuntu-rtld

.evergreen/install-dependencies.sh

@@ -105,3 +105,4 @@ echo "npm location: $(which npm)"
 echo "npm version: $(npm -v)"
 
 npm install "${NPM_OPTIONS}"
+ldd build/*/kerberos.node || true

binding.gyp

@@ -7,6 +7,9 @@
       'sources': [
         'src/kerberos.cc'
       ],
+      'variables': {
+        'kerberos_use_rtld%': 'false'
+      },
       'xcode_settings': {
         'GCC_ENABLE_CPP_EXCEPTIONS': 'YES',
         'CLANG_CXX_LIBRARY': 'libc++',
@@ -36,7 +39,9 @@
             'src/unix/base64.cc',
             'src/unix/kerberos_gss.cc',
             'src/unix/kerberos_unix.cc'
-          ],
+          ]
+        }],
+        ['(OS=="mac" or OS=="linux") and (kerberos_use_rtld!="true")', {
           'link_settings': {
             'libraries': [
               '-lkrb5',
@@ -53,6 +58,14 @@
             }]
           ]
         }],
+        ['(OS=="mac" or OS=="linux") and (kerberos_use_rtld=="true")', {
+          'defines': ['KERBEROS_USE_RTLD=1'],
+          'link_settings': {
+            'libraries': [
+              '-ldl',
+            ]
+          },
+        }],
         ['OS=="win"',  {
           'sources': [
             'src/win32/kerberos_sspi.cc',

src/kerberos.cc

@@ -171,6 +171,10 @@ void TestMethod(const CallbackInfo& info) {
 }
 
 static Object Init(Env env, Object exports) {
+    std::string libraries_unavailable_error;
+    if (!kerberos_libraries_available(&libraries_unavailable_error)) {
+        throw Error::New(env, libraries_unavailable_error);
+    }
     Function KerberosClientCtor = KerberosClient::Init(env);
     Function KerberosServerCtor = KerberosServer::Init(env);
     exports["KerberosClient"] = KerberosClientCtor;

src/kerberos.h

@@ -13,6 +13,8 @@
 
 namespace node_kerberos {
 
+bool kerberos_libraries_available(std::string* error_out);
+
 class KerberosServer : public Napi::ObjectWrap<KerberosServer> {
    public:
     static Napi::Function Init(Napi::Env env);