Add FFI JNI JSON RPC bridge (#2326)

* Add FFI JNI JSON RPC bridge
* Add FFI instance list API

easytier-contrib/easytier-android-jni/src/json_rpc_api.rs

@@ -0,0 +1,91 @@
+use std::{
+    ffi::{CStr, c_char},
+    ptr,
+};
+
+use easytier_ffi::{call_json_rpc, free_string};
+use jni::JNIEnv;
+use jni::objects::{JClass, JString};
+use jni::sys::jstring;
+
+use crate::{
+    error::{get_last_error, throw_exception},
+    strings::{jstring_to_cstring, optional_jstring_to_cstring},
+};
+
+pub(crate) fn call_json_rpc_jni(
+    mut env: JNIEnv,
+    _class: JClass,
+    service_name: JString,
+    method_name: JString,
+    domain_name: JString,
+    payload_json: JString,
+) -> jstring {
+    let service_name_cstr = match jstring_to_cstring(&mut env, &service_name) {
+        Ok(cstr) => cstr,
+        Err(e) => {
+            throw_exception(&mut env, &format!("Invalid service name: {}", e));
+            return ptr::null_mut();
+        }
+    };
+    let method_name_cstr = match jstring_to_cstring(&mut env, &method_name) {
+        Ok(cstr) => cstr,
+        Err(e) => {
+            throw_exception(&mut env, &format!("Invalid method name: {}", e));
+            return ptr::null_mut();
+        }
+    };
+    let domain_name_cstr = match optional_jstring_to_cstring(&mut env, &domain_name) {
+        Ok(cstr) => cstr,
+        Err(e) => {
+            throw_exception(&mut env, &format!("Invalid domain name: {}", e));
+            return ptr::null_mut();
+        }
+    };
+    let payload_json_cstr = match jstring_to_cstring(&mut env, &payload_json) {
+        Ok(cstr) => cstr,
+        Err(e) => {
+            throw_exception(&mut env, &format!("Invalid payload JSON: {}", e));
+            return ptr::null_mut();
+        }
+    };
+
+    let domain_name_ptr = domain_name_cstr
+        .as_ref()
+        .map_or(ptr::null(), |cstr| cstr.as_ptr());
+    let mut response_ptr: *const c_char = ptr::null();
+    let result = unsafe {
+        call_json_rpc(
+            service_name_cstr.as_ptr(),
+            method_name_cstr.as_ptr(),
+            domain_name_ptr,
+            payload_json_cstr.as_ptr(),
+            &mut response_ptr,
+        )
+    };
+
+    if result != 0 {
+        if let Some(error) = get_last_error() {
+            throw_exception(&mut env, &error);
+        }
+        return ptr::null_mut();
+    }
+
+    if response_ptr.is_null() {
+        throw_exception(&mut env, "JSON RPC returned a null response");
+        return ptr::null_mut();
+    }
+
+    let response = unsafe { CStr::from_ptr(response_ptr) }
+        .to_string_lossy()
+        .into_owned();
+    free_string(response_ptr);
+
+    match env.new_string(&response) {
+        Ok(jstr) => jstr.into_raw(),
+        Err(_) => {
+            throw_exception(&mut env, "Failed to create JSON RPC response string");
+            ptr::null_mut()
+        }
+    }
+}

easytier-contrib/easytier-android-jni/src/lib.rs

@@ -9,7 +9,9 @@
 //! - `parseConfig(config)`: validate TOML config text.
 //! - `runNetworkInstance(config)`: start a local network instance.
 //! - `retainNetworkInstance(instanceNames)`: retain named instances and stop the rest.
+//! - `listInstances()`: return running instance names and IDs as JSON.
 //! - `collectNetworkInfos()`: return running instance info as a JSON string.
+//! - `callJsonRpc(...)`: call an exposed EasyTier RPC service with JSON payload.
 //!
 //! Config server client APIs:
 //! - `startConfigServerClient(url, hostname, machineId, secureMode, callback)`:
@@ -28,6 +30,7 @@ mod callback;
 mod config_server_api;
 mod data_plane_api;
 mod error;
+mod json_rpc_api;
 mod logger;
 mod network_api;
 mod strings;
@@ -126,6 +129,53 @@ pub extern "system" fn Java_com_easytier_jni_EasyTierJNI_collectNetworkInfos(
     network_api::collect_network_infos_jni(env, class, max_length)
 }
 
+/// List running network instance names and IDs.
+///
+/// Java signature:
+/// `EasyTierJNI.listInstances(maxLength: Int): String?`
+///
+/// Returns a JSON object whose keys are instance names and whose values are
+/// instance ID strings. On failure this returns null and throws
+/// `RuntimeException`.
+#[unsafe(no_mangle)]
+pub extern "system" fn Java_com_easytier_jni_EasyTierJNI_listInstances(
+    env: JNIEnv,
+    class: JClass,
+    max_length: jint,
+) -> jstring {
+    logger::init();
+    network_api::list_instances_jni(env, class, max_length)
+}
+
+/// Call an exposed EasyTier RPC method using protobuf JSON.
+///
+/// Java signature:
+/// `EasyTierJNI.callJsonRpc(serviceName, methodName, domainName, payloadJson): String?`
+///
+/// Instance lifecycle management RPCs are intentionally not exposed here. Use
+/// the dedicated EasyTierJNI instance APIs for start/retain/delete/collect.
+/// `payloadJson` must include any `instance` selector required by the target
+/// RPC. On failure this returns null and throws `RuntimeException`.
+#[unsafe(no_mangle)]
+pub extern "system" fn Java_com_easytier_jni_EasyTierJNI_callJsonRpc(
+    env: JNIEnv,
+    class: JClass,
+    service_name: JString,
+    method_name: JString,
+    domain_name: JString,
+    payload_json: JString,
+) -> jstring {
+    logger::init();
+    json_rpc_api::call_json_rpc_jni(
+        env,
+        class,
+        service_name,
+        method_name,
+        domain_name,
+        payload_json,
+    )
+}
+
 /// Return the latest FFI/JNI error string for the calling thread.
 ///
 /// Java signature:

easytier-contrib/easytier-android-jni/src/network_api.rs

@@ -2,8 +2,8 @@ use std::{ffi::CStr, ptr};
 
 use easytier::proto::api::manage::{NetworkInstanceRunningInfo, NetworkInstanceRunningInfoMap};
 use easytier_ffi::{
-    KeyValuePair, collect_network_infos, parse_config, retain_network_instance,
-    run_network_instance, set_tun_fd,
+    KeyValuePair, collect_network_infos, free_string, list_instance, parse_config,
+    retain_network_instance, run_network_instance, set_tun_fd,
 };
 use jni::JNIEnv;
 use jni::objects::{JClass, JObjectArray, JString};
@@ -190,16 +190,18 @@ pub(crate) fn collect_network_infos_jni(
                 break;
             }
 
-            let key = CStr::from_ptr(key_ptr).to_string_lossy();
-            let val = CStr::from_ptr(val_ptr).to_string_lossy();
-            let value = match serde_json::from_str::<NetworkInstanceRunningInfo>(val.as_ref()) {
+            let key = CStr::from_ptr(key_ptr).to_string_lossy().into_owned();
+            let val = CStr::from_ptr(val_ptr).to_string_lossy().into_owned();
+            free_string(key_ptr);
+            free_string(val_ptr);
+            let value = match serde_json::from_str::<NetworkInstanceRunningInfo>(&val) {
                 Ok(v) => v,
                 Err(_) => {
                     throw_exception(&mut env, "Failed to parse JSON");
                     continue;
                 }
             };
-            ret.map.insert(key.to_string(), value);
+            ret.map.insert(key, value);
         }
 
         let json_str = serde_json::to_string(&ret).unwrap_or_else(|_| "{}".to_string());
@@ -212,3 +214,48 @@ pub(crate) fn collect_network_infos_jni(
         }
     }
 }
+
+pub(crate) fn list_instances_jni(mut env: JNIEnv, _class: JClass, max_length: jint) -> jstring {
+    let max_length = max_length.max(0) as usize;
+    let mut infos = vec![
+        KeyValuePair {
+            key: ptr::null(),
+            value: ptr::null(),
+        };
+        max_length
+    ];
+
+    unsafe {
+        let count = list_instance(infos.as_mut_ptr(), max_length);
+        if count < 0 {
+            if let Some(error) = get_last_error() {
+                throw_exception(&mut env, &error);
+            }
+            return ptr::null_mut();
+        }
+
+        let mut ret = serde_json::Map::new();
+        for info in infos.iter().take(count as usize) {
+            let key_ptr = info.key;
+            let val_ptr = info.value;
+            if key_ptr.is_null() || val_ptr.is_null() {
+                break;
+            }
+
+            let key = CStr::from_ptr(key_ptr).to_string_lossy().into_owned();
+            let val = CStr::from_ptr(val_ptr).to_string_lossy().into_owned();
+            free_string(key_ptr);
+            free_string(val_ptr);
+            ret.insert(key, serde_json::Value::String(val));
+        }
+
+        let json_str = serde_json::Value::Object(ret).to_string();
+        match env.new_string(&json_str) {
+            Ok(jstr) => jstr.into_raw(),
+            Err(_) => {
+                throw_exception(&mut env, "Failed to create instance list JSON string");
+                ptr::null_mut()
+            }
+        }
+    }
+}