IPtProxy

Obfs4proxy and Snowflake Pluggable Transports for iOS and Android

Both Obfs4proxy and Snowflake Pluggable Transports are written in Go, which is a little annoying to use on iOS and Android. This project encapsulates all the machinations to make it work and provides an easy to install binary including a wrapper around both.

Problems solved in particular are:

• One cannot compile main packages with gomobile. Both PTs are patched to avoid this.
• Both PTs are gathered under one roof here, since you cannot have two gomobile frameworks as dependencies, since there are some common Go runtime functions exported, which would create a name clash.
• Environment variable changes during runtime will not be recognized by goptlib when done from within Swift/Objective-C. Therefore, sensible values are hardcoded in the Go wrapper.
• Snowflake and Obfs4proxy are patched to accept all configuration parameters directly.
• Free ports to be used are automatically found by this library and returned to the consuming app. You can use the initial values for premature configuration just fine in situations, where you can be pretty sure, they're going to be available (typically on iOS). When that's not the case (e.g. multiple instances of your app on a multi-user Android), you should first start the transports and then use the returned ports for configuration of other components (e.g. Tor).

Both PTs are contained at their latest master commit, as per 2021-07-14.

iOS

Installation

IPtProxy is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'IPtProxy', '~> 1.5'

Getting Started

There's a companion library IPtProxyUI which explains the use of IPtProxy and provides all the necessary UI and additional information to use this library completely in a Tor context.

Android

Installation

IPtProxy is available through JitPack. To install it, simply add the following line to your build.gradle file:

implementation 'com.github.tladesignz:IPtProxy:1.5.0'

And this to your root build.gradle at the end of repositories:

allprojects {
	repositories {
		// ...
		maven { url 'https://jitpack.io' }
	}
}

For newer Android Studio projects created in Android Studio Bumblebee | 2021.1.1 or newer, the JitPack repository needs to be added into the root level file settings.gradle instead of build.gradle:

dependencyResolutionManagement {
    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
    repositories {
	  // ...
        maven { url 'https://jitpack.io' }
    }
}

Getting Started

If you are building a new Android application be sure to declare that it uses the INTERNET permission in your Android Manifest:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="my.test.app">

    <uses-permission android:name="android.permission.INTERNET"/>
    <application ...

Before using IPtProxy you need to specify a place on disk for it to store its state information. We recommend the path returned by Context#getCacheDir():

File fileCacheDir = new File(getCacheDir(), "pt");

if (!fileCacheDir.exists()) fileCacheDir.mkdir();

IPtProxy.setStateLocation(fileCacheDir.getAbsolutePath());

Build

Requirements

This repository contains a precompiled iOS and Android version of IPtProxy. If you want to compile it yourself, you'll need Go 1.16 as a prerequisite.

You will also need Xcode installed when compiling for iOS and an Android NDK when compiling for Android.

The build script needs the gomobile binary and will install it, if not available, yet. However, you'll still need to make it accessible in your $PATH.

So, if it's not already, add $GOPATH/bin to $PATH. The default location for $GOPATH is $HOME/go:

export PATH=$HOME/go/bin/:$PATH` 

iOS

Make sure Xcode and Xcode's command line tools are installed. Then run

rm -rf IPtProxy.xcframework && ./build.sh

This will create an IPtProxy.xcframework, which you can directly drop in your app, if you don't want to rely on CocoaPods.

Android

Make sure that javac is in your $PATH. If you do not have a JDK instance, on Debian systems you can install it with:

apt install default-jdk 

If they aren't already, make sure the $ANDROID_HOME and $ANDROID_NDK_HOME environment variables are set:

export ANDROID_HOME=~/Android/Sdk
export ANDROID_NDK_HOME=$ANDROID_HOME/ndk/$NDK_VERSION

rm -rf IPtProxy.aar IPtProxy-sources.jar && ./build.sh android

This will create an IPtProxy.aar file, which you can directly drop in your app, if you don't want to rely on JitPack.

On certain CPU architectures gobind might fail with this error due to setting a flag that is no longer supported by Go 1.16:

go tool compile: exit status 1
unsupported setting GO386=387. Consider using GO386=softfloat instead.
gomobile: go build -v -buildmode=c-shared -o=/tmp/gomobile-work-855414073/android/src/main/jniLibs/x86/libgojni.so ./gobind failed: exit status 1

If this is the case, you will need to set this flag to build IPtProxy:

export GO386=sse2

Authors

• Benjamin Erhart, berhart@netzarchitekten.com
• Nathan Freitas
• Bim

for the Guardian Project https://guardianproject.info

License

IPtProxy is available under the MIT license. See the LICENSE file for more info.