Support IPv6 and host names in socks5 mode

Closes #343
emanuele-f · Aug 20, 2023 · 6d7708e · 6d7708e
1 parent 958fc6a
commit 6d7708e
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Showing 13 changed files with 99 additions and 20 deletions.
diff --git a/app/src/main/java/com/emanuelef/remote_capture/CaptureHelper.java b/app/src/main/java/com/emanuelef/remote_capture/CaptureHelper.java
@@ -23,6 +23,8 @@
 import android.content.ActivityNotFoundException;
 import android.content.Intent;
 import android.net.VpnService;
+import android.os.Handler;
+import android.os.Looper;
 
 import com.emanuelef.remote_capture.interfaces.CaptureStartListener;
 import com.emanuelef.remote_capture.model.CaptureSettings;
@@ -34,7 +36,11 @@
 import androidx.appcompat.app.AlertDialog;
 import androidx.core.content.ContextCompat;
 
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+
 public class CaptureHelper {
+    private static final String TAG = "CaptureHelper";
     private final ComponentActivity mActivity;
     private final ActivityResultLauncher<Intent> mLauncher;
     private CaptureSettings mSettings;
@@ -48,7 +54,7 @@ public CaptureHelper(ComponentActivity activity) {
 
     private void captureServiceResult(final ActivityResult result) {
         if(result.getResultCode() == Activity.RESULT_OK)
-            startCaptureOk();
+            resolveHosts();
         else if(mListener != null) {
             Utils.showToastLong(mActivity, R.string.vpn_setup_failed);
             mListener.onCaptureStartResult(false);
@@ -64,14 +70,55 @@ private void startCaptureOk() {
             mListener.onCaptureStartResult(true);
     }
 
+    private String resolveHost(String host) {
+        Log.d(TAG, "Resolving host: " + host);
+
+        try {
+            return InetAddress.getByName(host).getHostAddress();
+        } catch (UnknownHostException ignored) {}
+
+        return null;
+    }
+
+    private String doResolveHosts() {
+        // NOTE: hosts must be resolved before starting the VPN and in a separate thread
+        String resolved;
+
+        if((resolved = resolveHost(mSettings.socks5_proxy_address)) == null)
+            return mSettings.socks5_proxy_address;
+        else if(!resolved.equals(mSettings.socks5_proxy_address)) {
+            Log.i(TAG, "Resolved SOCKS5 proxy address: " + resolved);
+            mSettings.socks5_proxy_address = resolved;
+        }
+
+        return null;
+    }
+
+    private void resolveHosts() {
+        final Handler handler = new Handler(Looper.getMainLooper());
+
+        (new Thread(() -> {
+            String failed_host = doResolveHosts();
+
+            handler.post(() -> {
+                if(failed_host == null)
+                    startCaptureOk();
+                else {
+                    Utils.showToastLong(mActivity, R.string.host_resolution_failed, failed_host);
+                    mListener.onCaptureStartResult(false);
+                }
+            });
+        })).start();
+    }
+
     public void startCapture(CaptureSettings settings) {
         if(CaptureService.isServiceActive())
             CaptureService.stopService();
 
         mSettings = settings;
 
         if(settings.root_capture || settings.readFromPcap()) {
-            startCaptureOk();
+            resolveHosts();
             return;
         }
 
@@ -93,7 +140,7 @@ public void startCapture(CaptureSettings settings) {
                     })
                     .show();
         } else
-            startCaptureOk();
+            resolveHosts();
     }
 
     public void setListener(CaptureStartListener listener) {

diff --git a/app/src/main/java/com/emanuelef/remote_capture/Utils.java b/app/src/main/java/com/emanuelef/remote_capture/Utils.java
@@ -484,6 +484,10 @@ public static boolean isLocalNetworkAddress(InetAddress checkAddress) {
     }
 
     public static boolean isLocalNetworkAddress(String checkAddress) {
+        // this check is necessary as otherwise host resolution would be triggered on the main thread
+        if(!validateIpAddress(checkAddress))
+            return false;
+
         try {
             return isLocalNetworkAddress(InetAddress.getByName(checkAddress));
         } catch (UnknownHostException ignored) {

diff --git a/app/src/main/java/com/emanuelef/remote_capture/activities/CaptureCtrl.java b/app/src/main/java/com/emanuelef/remote_capture/activities/CaptureCtrl.java
@@ -220,7 +220,7 @@ private String checkRemoteServerNotAllowed(CaptureSettings settings) {
 
         if(settings.socks5_enabled &&
                 !Utils.isLocalNetworkAddress(settings.socks5_proxy_address) &&
-                !Prefs.getSocks5ProxyAddress(prefs).equals(settings.socks5_proxy_address))
+                !Prefs.getSocks5ProxyHost(prefs).equals(settings.socks5_proxy_address))
             return settings.socks5_proxy_address;
 
         // ok

diff --git a/app/src/main/java/com/emanuelef/remote_capture/activities/MainActivity.java b/app/src/main/java/com/emanuelef/remote_capture/activities/MainActivity.java
@@ -158,7 +158,7 @@ protected void onCreate(Bundle savedInstanceState) {
         mCapHelper = new CaptureHelper(this);
         mCapHelper.setListener(success -> {
             if(!success) {
-                Log.w(TAG, "VPN request failed");
+                Log.w(TAG, "Capture start failed");
                 appStateReady();
             }
         });
@@ -684,7 +684,7 @@ private boolean showRemoteServerAlert() {
             return false; // already acknowledged
 
         if(((Prefs.getDumpMode(mPrefs) == Prefs.DumpMode.UDP_EXPORTER) && !Utils.isLocalNetworkAddress(Prefs.getCollectorIp(mPrefs))) ||
-                (Prefs.getSocks5Enabled(mPrefs) && !Utils.isLocalNetworkAddress(Prefs.getSocks5ProxyAddress(mPrefs)))) {
+                (Prefs.getSocks5Enabled(mPrefs) && !Utils.isLocalNetworkAddress(Prefs.getSocks5ProxyHost(mPrefs)))) {
             Log.i(TAG, "Showing possible scan notice");
 
             AlertDialog dialog = new AlertDialog.Builder(this)

diff --git a/app/src/main/java/com/emanuelef/remote_capture/fragments/prefs/Socks5Settings.java b/app/src/main/java/com/emanuelef/remote_capture/fragments/prefs/Socks5Settings.java
@@ -33,7 +33,7 @@
 import java.util.Objects;
 
 public class Socks5Settings extends PreferenceFragmentCompat {
-    private EditTextPreference mProxyIp;
+    private EditTextPreference mProxyHost;
     private EditTextPreference mProxyPort;
     private EditTextPreference mUsername;
     private EditTextPreference mPassword;
@@ -44,8 +44,8 @@ public void onCreatePreferences(@Nullable Bundle savedInstanceState, @Nullable S
         setPreferencesFromResource(R.xml.socks5_preferences, rootKey);
 
         /* SOCKS5 Proxy IP validation */
-        mProxyIp = Objects.requireNonNull(findPreference(Prefs.PREF_SOCKS5_PROXY_IP_KEY));
-        mProxyIp.setOnPreferenceChangeListener((preference, newValue) -> Utils.validateIpAddress(newValue.toString()));
+        mProxyHost = Objects.requireNonNull(findPreference(Prefs.PREF_SOCKS5_PROXY_IP_KEY));
+        mProxyHost.setOnPreferenceChangeListener((preference, newValue) -> Utils.validateHost(newValue.toString()));
 
         /* SOCKS5 Proxy port validation */
         mProxyPort = Objects.requireNonNull(findPreference(Prefs.PREF_SOCKS5_PROXY_PORT_KEY));
@@ -70,7 +70,7 @@ public void onCreatePreferences(@Nullable Bundle savedInstanceState, @Nullable S
     }
 
     private void toggleVisisiblity(boolean socks5_enabled, boolean auth_enabled) {
-        mProxyIp.setVisible(socks5_enabled);
+        mProxyHost.setVisible(socks5_enabled);
         mProxyPort.setVisible(socks5_enabled);
         mSocks5AuthEnabled.setVisible(socks5_enabled);
 

diff --git a/app/src/main/java/com/emanuelef/remote_capture/model/CaptureSettings.java b/app/src/main/java/com/emanuelef/remote_capture/model/CaptureSettings.java
@@ -44,7 +44,7 @@ public CaptureSettings(Context ctx, SharedPreferences prefs) {
         collector_port = Prefs.getCollectorPort(prefs);
         http_server_port = Prefs.getHttpServerPort(prefs);
         socks5_enabled = Prefs.getSocks5Enabled(prefs);
-        socks5_proxy_address = Prefs.getSocks5ProxyAddress(prefs);
+        socks5_proxy_address = Prefs.getSocks5ProxyHost(prefs);
         socks5_proxy_port = Prefs.getSocks5ProxyPort(prefs);
         socks5_username = Prefs.isSocks5AuthEnabled(prefs) ? Prefs.getSocks5Username(prefs) : "";
         socks5_password = Prefs.isSocks5AuthEnabled(prefs) ? Prefs.getSocks5Password(prefs) : "";

diff --git a/app/src/main/java/com/emanuelef/remote_capture/model/Prefs.java b/app/src/main/java/com/emanuelef/remote_capture/model/Prefs.java
@@ -170,7 +170,7 @@ public static void setPortMappingEnabled(SharedPreferences p, boolean enabled) {
     public static int getHttpServerPort(SharedPreferences p) { return(Integer.parseInt(p.getString(Prefs.PREF_HTTP_SERVER_PORT, "8080"))); }
     public static boolean getTlsDecryptionEnabled(SharedPreferences p) { return(p.getBoolean(PREF_TLS_DECRYPTION_KEY, false)); }
     public static boolean getSocks5Enabled(SharedPreferences p)     { return(p.getBoolean(PREF_SOCKS5_ENABLED_KEY, false)); }
-    public static String getSocks5ProxyAddress(SharedPreferences p) { return(p.getString(PREF_SOCKS5_PROXY_IP_KEY, "0.0.0.0")); }
+    public static String getSocks5ProxyHost(SharedPreferences p)    { return(p.getString(PREF_SOCKS5_PROXY_IP_KEY, "0.0.0.0")); }
     public static int getSocks5ProxyPort(SharedPreferences p)       { return(Integer.parseInt(p.getString(Prefs.PREF_SOCKS5_PROXY_PORT_KEY, "8080"))); }
     public static boolean isSocks5AuthEnabled(SharedPreferences p)  { return(p.getBoolean(PREF_SOCKS5_AUTH_ENABLED_KEY, false)); }
     public static String getSocks5Username(SharedPreferences p)     { return(p.getString(PREF_SOCKS5_USERNAME_KEY, "")); }

diff --git a/app/src/main/jni/core/capture_vpn.c b/app/src/main/jni/core/capture_vpn.c
@@ -473,9 +473,7 @@ int run_vpn(pcapdroid_t *pd) {
     new_dns_server = 0;
 
     if(pd->socks5.enabled) {
-        zdtun_ip_t dnatip = {0};
-        dnatip.ip4 = pd->socks5.proxy_ip;
-        zdtun_set_socks5_proxy(zdt, &dnatip, pd->socks5.proxy_port, 4);
+        zdtun_set_socks5_proxy(zdt, &pd->socks5.proxy_ip, pd->socks5.proxy_port, pd->socks5.proxy_ipver);
 
         if(pd->socks5.proxy_user[0] && pd->socks5.proxy_pass[0])
             zdtun_set_socks5_userpass(zdt, pd->socks5.proxy_user, pd->socks5.proxy_pass);

diff --git a/app/src/main/jni/core/jni_impl.c b/app/src/main/jni/core/jni_impl.c
@@ -599,7 +599,7 @@ Java_com_emanuelef_remote_1capture_CaptureService_runPacketLoop(JNIEnv *env, jcl
             },
             .socks5 = {
                     .enabled = (bool) getIntPref(env, vpn, "getSocks5Enabled"),
-                    .proxy_ip = getIPv4Pref(env, vpn, "getSocks5ProxyAddress"),
+                    .proxy_ip = getIPPref(env, vpn, "getSocks5ProxyAddress", &pd.socks5.proxy_ipver),
                     .proxy_port = htons(getIntPref(env, vpn, "getSocks5ProxyPort")),
             },
             .malware_detection = {
@@ -1149,6 +1149,32 @@ u_int32_t getIPv4Pref(JNIEnv *env, jobject vpn_inst, const char *key) {
 
 /* ******************************************************* */
 
+zdtun_ip_t getIPPref(JNIEnv *env, jobject vpn_inst, const char *key, int *ip_ver) {
+    zdtun_ip_t rv = {};
+
+    jmethodID midMethod = jniGetMethodID(env, cls.vpn_service, key, "()Ljava/lang/String;");
+    jstring obj = (*env)->CallObjectMethod(env, vpn_inst, midMethod);
+
+    if(!jniCheckException(env)) {
+        const char *value = (*env)->GetStringUTFChars(env, obj, 0);
+        log_d("getIPPref(%s) = %s", key, value);
+
+        if(*value) {
+            *ip_ver = zdtun_parse_ip(value, &rv);
+
+            if(*ip_ver < 0)
+                log_e("%s() returned invalid IP address: %s", key, value);
+        }
+
+        (*env)->ReleaseStringUTFChars(env, obj, value);
+    }
+
+    (*env)->DeleteLocalRef(env, obj);
+    return(rv);
+}
+
+/* ******************************************************* */
+
 struct in6_addr getIPv6Pref(JNIEnv *env, jobject vpn_inst, const char *key) {
     struct in6_addr addr = {0};
 

diff --git a/app/src/main/jni/core/pcapdroid.h b/app/src/main/jni/core/pcapdroid.h
@@ -239,8 +239,9 @@ typedef struct pcapdroid {
 
     struct {
         bool enabled;
-        u_int32_t proxy_ip;
+        zdtun_ip_t proxy_ip;
         u_int32_t proxy_port;
+        int proxy_ipver;
         char proxy_user[32];
         char proxy_pass[32];
     } socks5;
@@ -395,6 +396,7 @@ uint16_t pd_ndpi2proto(ndpi_protocol proto);
 
 char* getStringPref(pcapdroid_t *pd, const char *key, char *buf, int bufsize);
 int getIntPref(JNIEnv *env, jobject vpn_inst, const char *key);
+zdtun_ip_t getIPPref(JNIEnv *env, jobject vpn_inst, const char *key, int *ip_ver);
 uint32_t getIPv4Pref(JNIEnv *env, jobject vpn_inst, const char *key);
 struct in6_addr getIPv6Pref(JNIEnv *env, jobject vpn_inst, const char *key);
 void getApplicationByUid(pcapdroid_t *pd, jint uid, char *buf, int bufsize);

diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
@@ -130,6 +130,7 @@
     <string name="socks5_auth">SOCKS5 authentication</string>
     <string name="socks5_auth_summary">Authenticate to the proxy via username and password</string>
     <string name="proxy_ip_address">Proxy IP address</string>
+    <string name="proxy_host">Proxy host</string>
     <string name="proxy_port">Proxy port</string>
     <string name="root_capture">Capture as root</string>
     <string name="root_capture_summary">Allows PCAPdroid to run with other VPN apps</string>
@@ -486,4 +487,5 @@
     <string name="root_capture_start_failed">Capture start failure. Ensure that the device is rooted with Magisk</string>
     <string name="pcap_read_error">PCAP read error</string>
     <string name="pcap_file_load_aborted">PCAP file loading aborted</string>
+    <string name="host_resolution_failed">"Could not resolve host %1$s</string>
 </resources>
diff --git a/app/src/main/res/xml/socks5_preferences.xml b/app/src/main/res/xml/socks5_preferences.xml
@@ -11,7 +11,7 @@
 
     <EditTextPreference
         app:key="socks5_proxy_ip_address"
-        app:title="@string/proxy_ip_address"
+        app:title="@string/proxy_host"
         app:defaultValue="0.0.0.0"
         app:iconSpaceReserved="false"
         app:useSimpleSummaryProvider="true" />

diff --git a/docs/app_api.md b/docs/app_api.md
@@ -85,8 +85,8 @@ As shown above, the capture settings can be specified by using intent extras. Th
 | http_server_port        | int    |     |      | the HTTP server port in http_server mode                           |
 | pcap_uri                | string |     |      | the URI for the PCAP dump in pcap_file mode (overrides pcap_name)  |
 | socks5_enabled          | bool   |     | vpn  | true to redirect the TCP connections to a SOCKS5 proxy             |
-| socks5_proxy_ip_address | string |     | vpn  | the IP address of the SOCKS5 proxy                                 |
-| socks5_proxy_port       | int    |     | vpn  | the TCP port of the SOCKS5 proxy                                   |
+| socks5_proxy_ip_address | string |     | vpn  | the SOCKS5 proxy host                                              |
+| socks5_proxy_port       | int    |     | vpn  | the SOCKS5 proxy port                                              |
 | root_capture            | bool   |     |      | true to capture packets in root mode, false to use the VPNService  |
 | pcapdroid_trailer       | bool   |     |      | true to enable the PCAPdroid trailer                               |
 | capture_interface       | string |     | root | @inet \| any \| ifname - network interface to use in root mode     |