Refactoring

app/src/main/java/eu/faircode/email/ConnectionHelper.java

@@ -83,6 +83,12 @@ public class ConnectionHelper {
             "SE" // Sweden
     ));
 
+    static {
+        System.loadLibrary("fairemail");
+    }
+
+    public static native int jni_socket_keep_alive(int fd, int seconds);
+
     static class NetworkState {
         private Boolean connected = null;
         private Boolean suitable = null;

app/src/main/java/eu/faircode/email/EmailService.java

@@ -149,12 +149,6 @@ public class EmailService implements AutoCloseable {
     // TLS_FALLBACK_SCSV https://tools.ietf.org/html/rfc7507
     // TLS_EMPTY_RENEGOTIATION_INFO_SCSV https://tools.ietf.org/html/rfc5746
 
-    static {
-        System.loadLibrary("fairemail");
-    }
-
-    private static native int jni_socket_keep_alive(int fd, int seconds);
-
     private EmailService() {
         // Prevent instantiation
     }
@@ -1068,7 +1062,7 @@ public class EmailService implements AutoCloseable {
                 Log.i("Enabling TCP keep alive");
 
                 int fd = ParcelFileDescriptor.fromSocket(socket).getFd();
-                int errno = jni_socket_keep_alive(fd, TCP_KEEP_ALIVE_INTERVAL);
+                int errno = ConnectionHelper.jni_socket_keep_alive(fd, TCP_KEEP_ALIVE_INTERVAL);
                 if (errno == 0)
                     Log.i("Enabled TCP keep alive");
                 else

app/src/main/jni/fairemail.cc

@@ -86,7 +86,7 @@ Java_eu_faircode_email_TextHelper_jni_1detect_1language(JNIEnv *env, jclass claz
 
 extern "C"
 JNIEXPORT jint JNICALL
-Java_eu_faircode_email_EmailService_jni_1socket_1keep_1alive(
+Java_eu_faircode_email_ConnectionHelper_jni_1socket_1keep_1alive(
         JNIEnv *env, jclass clazz,
         jint fd, jint seconds) {
     // https://tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/#setsockopt