Add DIDKit FFI

Close #1

.cargo/config

@@ -0,0 +1,11 @@
+[target.i686-linux-android]
+linker = "i686-linux-android16-clang"
+
+[target.armv7-linux-androideabi]
+linker = "armv7a-linux-androideabi16-clang"
+
+[target.aarch64-linux-android]
+linker = "aarch64-linux-android21-clang"
+
+[target.x86_64-linux-android]
+linker = "x86_64-linux-android21-clang"

.github/workflows/build.yml

@@ -38,7 +38,7 @@ jobs:
           ~/.cargo/registry
           ~/.cargo/git
           target
-        key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.toml', '**.rs') }}
+        key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.toml', 'lib/Makefile', '**.rs') }}
         restore-keys: |
           ${{ runner.os }}-cargo-
 
@@ -47,3 +47,45 @@ jobs:
 
     - name: Test
       run: cargo test --verbose --workspace
+
+    - name: Install Rust Android targets
+      run: make -C lib install-rustup-android
+
+    - name: Install JDK
+      uses: actions/setup-java@v1
+      with:
+        java-version: 1.8
+
+    - name: Install Flutter
+      uses: subosito/flutter-action@v1
+
+    - name: Opt out of Dart/Flutter analytics
+      run: |
+        dart --disable-analytics
+        flutter --suppress-analytics config --no-analytics
+
+    - name: Install Android SDK
+      uses: android-actions/setup-android@v2
+
+    - name: Cache Android NDK
+      id: ndk-cache
+      uses: actions/cache@v2
+      with:
+        path: ${{ env.ANDROID_SDK_ROOT }}/ndk-bundle
+        key: ${{ runner.os }}-ndk-bundle
+
+    - name: Install Android NDK
+      if: steps.ndk-cache.outputs.cache-hit != 'true'
+      run: $ANDROID_SDK_ROOT/tools/bin/sdkmanager ndk-bundle
+
+    - name: Test C FFI
+      run: make -C lib ../target/test/c.stamp
+
+    - name: Test JNI
+      run: make -C lib ../target/test/java.stamp
+
+    - name: Test Dart/Flutter plugin
+      run: make -C lib ../target/test/flutter.stamp
+
+    - name: Build Android Archive
+      run: make -C lib ../target/test/aar.stamp

Cargo.toml

@@ -3,4 +3,5 @@ members = [
   "http",
   "cli",
   "lib",
+  "lib/cbindings"
 ]

lib/.gitignore

@@ -0,0 +1 @@
+/tmp

lib/Cargo.toml

@@ -6,3 +6,7 @@ edition = "2018"
 
 [dependencies]
 ssi = { path = "../../ssi" }
+jni = "0.17"
+
+[lib]
+crate-type = ["lib", "cdylib"]

lib/FFI.md

@@ -0,0 +1,8 @@
+## FFI
+
+The DIDKit library is written in Rust, but has bindings for other languages and environments:
+
+- [C](c/)
+- [Java](java/)
+- [Android](android/)
+- [Flutter](flutter/)

lib/Makefile

@@ -0,0 +1,102 @@
+# didkit/lib/Makefile
+
+TARGET=../target
+
+.PHONY: test
+test: $(TARGET)/test/c.stamp \
+	$(TARGET)/test/java.stamp \
+	$(TARGET)/test/aar.stamp \
+	$(TARGET)/test/flutter.stamp
+
+## Setup
+
+android/res $(TARGET)/test $(TARGET)/jvm:
+	mkdir -p $@
+
+## Rust
+
+RUST_SRC=Cargo.toml $(wildcard src/*.rs src/*/*.rs src/*/*/*.rs)
+
+$(TARGET)/didkit.h: cbindgen.toml cbindings/build.rs cbindings/Cargo.toml $(RUST_SRC)
+	cargo build -p didkit-cbindings
+	test -s $@ && touch $@
+
+$(TARGET)/release/libdidkit.so: $(RUST_SRC)
+	cargo build --lib --release
+	strip $@
+
+## C
+
+$(TARGET)/test/c.stamp: $(TARGET)/cabi-test $(TARGET)/release/libdidkit.so | $(TARGET)/test
+	$(TARGET)/cabi-test
+	touch $@
+
+$(TARGET)/cabi-test: c/test.c $(TARGET)/didkit.h
+	$(CC) -I$(TARGET) $< -ldl -o $@
+
+## Java
+
+JAVA_SRC=$(wildcard java/*/*.java java/*/*/*.java java/*/*/*/*.java)
+
+$(TARGET)/test/java.stamp: $(TARGET)/jvm/com/spruceid/DIDKit.class $(TARGET)/release/libdidkit.so | $(TARGET)/test
+	java -Djava.class.path=$(TARGET)/jvm \
+		-Djava.library.path=$(TARGET)/release \
+		com.spruceid.DIDKit
+	touch $@
+
+$(TARGET)/jvm/com/spruceid/DIDKit.class: java/com/spruceid/DIDKit.java | $(TARGET)/jvm
+	javac $^ -d $(TARGET)/jvm -source 1.7 -target 1.7
+
+$(TARGET)/com_spruceid_DIDKit.h: java/com/spruceid/DIDkit.java
+	javac -h $(TARGET) $<
+
+$(TARGET)/didkit.jar: $(TARGET)/jvm/com/spruceid/DIDKit.class
+	jar -cf $@ -C $(TARGET)/jvm $(patsubst $(TARGET)/jvm/%,%,$^)
+
+## Android
+
+.PHONY: install-rustup-android
+install-rustup-android:
+	rustup target add i686-linux-android armv7-linux-androideabi aarch64-linux-android x86_64-linux-android
+
+ANDROID_SDK_ROOT ?= ~/Android/Sdk
+ANDROID_TOOLS ?= $(lastword $(wildcard $(ANDROID_SDK_ROOT)/build-tools/*))
+ANDROID_NDK_HOME ?= $(lastword $(wildcard \
+					$(ANDROID_SDK_ROOT)/ndk/* \
+					$(ANDROID_SDK_ROOT)/ndk-bundle))
+OS_NAME=$(shell uname | tr '[:upper:]' '[:lower:]')
+TOOLCHAIN=$(ANDROID_NDK_HOME)/toolchains/llvm/prebuilt/$(OS_NAME)-x86_64
+ANDROID_LIBS=\
+	$(TARGET)/i686-linux-android/release/libdidkit.so\
+	$(TARGET)/armv7-linux-androideabi/release/libdidkit.so\
+	$(TARGET)/aarch64-linux-android/release/libdidkit.so\
+	$(TARGET)/x86_64-linux-android/release/libdidkit.so
+
+$(TARGET)/test/aar.stamp: $(TARGET)/didkit.aar | $(TARGET)/test
+	rm -rf tmp/test-aar
+	mkdir -p tmp/test-aar
+	cd tmp/test-aar && unzip -q ../../$< || unzip -l ../../$< 
+	cd tmp/test-aar && unzip -qo classes.jar com/spruceid/DIDKit.class || unzip -l classes.jar
+	javap tmp/test-aar/com/spruceid/DIDKit.class | grep -q 'public class com.spruceid.DIDKit'
+	touch $@
+
+$(TARGET)/didkit.aar: $(TARGET)/didkit.jar android/AndroidManifest.xml android/R.txt $(ANDROID_LIBS) | android/res
+	$(ANDROID_TOOLS)/aapt package -f -S android/res -F $@ --ignore-assets '.*:*~:README.md' android
+
+$(TARGET)/%/release/libdidkit.so: $(RUST_SRC)
+	PATH=$(TOOLCHAIN)/bin:$(PATH) \
+	cargo build --lib --release --target $*
+	$(TOOLCHAIN)/bin/llvm-strip $@
+
+## Flutter
+
+$(TARGET)/test/flutter.stamp: flutter/lib/didkit.dart $(TARGET)/release/libdidkit.so | $(TARGET)/test
+	cd flutter && LD_LIBRARY_PATH=$$PWD \
+		flutter --suppress-analytics test
+	touch $@
+
+## Cleanup
+
+.PHONY: clean
+clean:
+	cargo clean

lib/android/AndroidManifest.xml

@@ -0,0 +1,3 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+  package="com.spruceid.DIDKit">
+</manifest>

lib/android/README.md

@@ -0,0 +1,17 @@
+# DIDKit - Android
+
+[Android Library (AAR file)][AAR] for DIDKit. The AAR file includes Java class files using [JNI][], and binary shared libraries for Android's supported architectures (x86, armeabi-v7a, arm64-v8a, x86\_64). It can be added to existing Android projects using Android Studio or Gradle.
+
+## Requires
+
+Android SDK and NDK, for Linux x86\_64
+
+## Build
+
+In the parent directory, run:
+```
+make target/didkit.aar
+```
+
+[AAR]: https://developer.android.com/studio/projects/android-library.html#aar-contents
+[JNI]: https://en.wikipedia.org/wiki/Java_Native_Interface

lib/android/classes.jar

@@ -0,0 +1 @@
+../../target/didkit.jar

lib/android/jni/arm64-v8a/libdidkit.so

@@ -0,0 +1 @@
+../../../../target/aarch64-linux-android/release/libdidkit.so

lib/android/jni/armeabi-v7a/libdidkit.so

@@ -0,0 +1 @@
+../../../../target/armv7-linux-androideabi/release/libdidkit.so

lib/android/jni/x86/libdidkit.so

@@ -0,0 +1 @@
+../../../../target/i686-linux-android/release/libdidkit.so

lib/android/jni/x86_64/libdidkit.so

@@ -0,0 +1 @@
+../../../../target/x86_64-linux-android/release/libdidkit.so

lib/c/README.md

@@ -0,0 +1,14 @@
+# DIDKit - C
+
+Shared Library for DIDKit. Intended to be compatible with C.
+
+## Build
+
+In the parent directory, run:
+```
+make ../target/release/libdidkit.so
+```
+
+## Android
+
+To build the C shared library for Android targets, build the [DIDKit Android library](../android/).

lib/c/test.c

@@ -0,0 +1,15 @@
+#include <dlfcn.h>
+#include <err.h>
+#include <stdio.h>
+#include "didkit.h"
+
+int main() {
+	void *lib = dlopen("../target/release/libdidkit.so", RTLD_NOW);
+	if (lib == NULL) errx(1, "dlopen: %s", dlerror());
+	const char *(*didkit_get_version)() = dlsym(lib, "didkit_get_version");
+	if (didkit_get_version == NULL) errx(1, "unable to find version function");
+	const char *version = didkit_get_version();
+	printf("C libdidkit version: %s\n", version);
+	int rc = dlclose(lib);
+	if (rc < 0) errx(1, "dlclose: %s", dlerror());
+}

lib/cbindgen.toml

@@ -0,0 +1,3 @@
+language = "C"
+autogen_warning = "// didkit.h - autogenerated by cbindgen"
+pragma_once = true

lib/cbindings/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "didkit-cbindings"
+version = "0.1.0"
+authors = ["Charles E. Lehner <[email protected]>"]
+edition = "2018"
+publish = false
+
+[build-dependencies]
+#didkit = { path = "../" }
+cbindgen = "0.14"

lib/cbindings/README.md

@@ -0,0 +1,5 @@
+# cbindings for didkit
+
+This crate builds a C header file for the didkit crate. It is a separate crate so that it runs after the didkit crate is built, rather than blocking compilation of the didkit crate. If there are syntax errors, the Rust compiler gives more useful output than would the failing build script using cbindgen.
+
+Related issue: [Cargo post-build script execution](https://github.com/rust-lang/cargo/issues/545)

lib/cbindings/build.rs

@@ -0,0 +1,23 @@
+extern crate cbindgen;
+
+use std::env;
+use std::path::Path;
+
+fn main() {
+    let crate_dir = env::var("CARGO_MANIFEST_DIR").unwrap();
+    let lib_dir = Path::new(&crate_dir).parent().unwrap();
+    let workspace_dir = lib_dir.parent().unwrap();
+
+    // Docs say to output into OUT_DIR, but then how do we use that?
+    // https://doc.rust-lang.org/cargo/reference/build-scripts.html#outputs-of-the-build-script
+    // https://stackoverflow.com/questions/63928113/is-there-a-way-to-change-out-dir-for-a-build-rs
+    // let out_dir = env::var("OUT_DIR").unwrap();
+    let out_dir = workspace_dir.join("target");
+    let out_file = out_dir.join("didkit.h");
+
+    cbindgen::generate(lib_dir)
+        .expect("Unable to generate bindings")
+        .write_to_file(&out_file);
+
+    println!("cargo:rerun-if-changed={:?}", &out_file);
+}

lib/cbindings/src/lib.rs

@@ -0,0 +1 @@
+// placeholder for build-only crate

lib/flutter/.gitignore

@@ -0,0 +1,7 @@
+.DS_Store
+.dart_tool/
+
+.packages
+.pub/
+
+build/

lib/flutter/.metadata

@@ -0,0 +1,10 @@
+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: 6b39acdc53bad8b3d51d1618e3df4e299b344d7c
+  channel: master
+
+project_type: plugin

lib/flutter/CHANGELOG.md

@@ -0,0 +1,3 @@
+## 0.0.1
+
+* TODO: Describe initial release.

lib/flutter/LICENSE

@@ -0,0 +1 @@
+TODO: Add your license here.

lib/flutter/README.md

@@ -0,0 +1,16 @@
+# DIDKit - Flutter
+
+[Flutter plugin][packages-plugins] for the DIDKit library. Includes Dart bindings, and functionality for Android and iOS.
+
+## Usage
+
+You can depend on this plugin as a [path dependency][path-packages].
+
+You will also need to build the DIDKit library for your target platforms.
+To do that for Android, trigger building the AAR file - in the parent directory:
+```
+make ../target/didkit.aar
+```
+
+[path-packages]: https://dart.dev/tools/pub/dependencies#path-packages
+[packages-plugins]: https://flutter.dev/developing-packages/

lib/flutter/android/.gitignore

@@ -0,0 +1,8 @@
+*.iml
+.gradle
+/local.properties
+/.idea/workspace.xml
+/.idea/libraries
+.DS_Store
+/build
+/captures

lib/flutter/android/build.gradle

@@ -0,0 +1,33 @@
+group 'com.spruceid.DIDKit'
+version '1.0'
+
+buildscript {
+    repositories {
+        google()
+        jcenter()
+    }
+
+    dependencies {
+        classpath 'com.android.tools.build:gradle:3.5.0'
+    }
+}
+
+rootProject.allprojects {
+    repositories {
+        google()
+        jcenter()
+    }
+}
+
+apply plugin: 'com.android.library'
+
+android {
+    compileSdkVersion 29
+
+    defaultConfig {
+        minSdkVersion 16
+    }
+    lintOptions {
+        disable 'InvalidPackage'
+    }
+}

lib/flutter/android/gradle.properties

@@ -0,0 +1,3 @@
+org.gradle.jvmargs=-Xmx1536M
+android.useAndroidX=true
+android.enableJetifier=true