First version that only builds obfs4proxy for Android and Linux

.gitignore

+/.idea
+/__pycache__
+/toolchain
+/jni
+/android-ndk
+/android-ndk.zip
+/obfs4proxy_*.zip
+/obfs4
\ No newline at end of file

build-obfs4proxy.py

+#!/usr/bin/env python3
+from glob import glob
+import os
+from shutil import move, rmtree
+from subprocess import check_call
+
+from utils import get_build_versions, ex, get_sha256, fail, zip_file
+
+NDK_DIR = 'android-ndk'
+REPO_DIR = 'obfs4'
+SOURCE = 'obfs4/obfs4proxy/*'
+
+
+def main():
+    # Get the latest versions for building
+    versions = get_build_versions(None)
+
+    # Setup Android NDK
+    setup_android_ndk(versions)
+
+    # Clone or reset the git repository
+    prepare_repo(versions)
+
+    # Install dependencies (of git HEAD)
+    ex(['go', 'get', '-d', versions['obfs4']['got-get']])
+
+    # Build for various Android versions
+    build_android()
+
+    # Build for 64-bit Linux
+    build_linux()
+
+
+def setup_android_ndk(versions):
+    if os.path.isdir(NDK_DIR):
+        # check that we are using the correct NDK
+        from configparser import ConfigParser
+        config = ConfigParser()
+        with open(os.path.join(NDK_DIR, 'source.properties'), 'rt') as f:
+            config.read_string('[default]\n' + str(f.read()))
+            revision = config.get('default', 'Pkg.Revision')
+
+        if revision != versions['ndk']['revision']:
+            print("Existing Android NDK has unexpected revision (%s). Deleting..." % revision)
+            rmtree(NDK_DIR)
+
+    if not os.path.isdir(NDK_DIR):
+        # download Android NDK
+        print("Downloading Android NDK...")
+        check_call(['wget', '-c', '--no-verbose', versions['ndk']['url'], '-O', 'android-ndk.zip'])
+
+        # check sha256 hash on downloaded file
+        is_hash = get_sha256('android-ndk.zip')
+        if is_hash != versions['ndk']['sha256']:
+            fail("Android NDK checksum does not match, should be %s" % is_hash)
+
+        # install the NDK
+        print("Unpacking Android NDK...")
+        ndk_dir_tmp = NDK_DIR + '-tmp'
+        check_call(['unzip', '-q', 'android-ndk.zip', '-d', ndk_dir_tmp])
+        content = os.listdir(ndk_dir_tmp)
+        if len(content) == 1 and content[0].startswith('android-ndk-r'):
+            move(os.path.join(ndk_dir_tmp, content[0]), NDK_DIR)
+            os.rmdir(ndk_dir_tmp)
+        else:
+            fail("Could not extract NDK: %s" % str(content))
+
+    os.putenv('ANDROID_NDK_HOME', os.path.abspath(NDK_DIR))
+
+
+def prepare_repo(versions):
+    if os.path.isdir(REPO_DIR):
+        # get latest commits and tags from remote
+        check_call(['git', 'fetch', 'origin'], cwd=REPO_DIR)
+    else:
+        # clone repo
+        url = versions['obfs4']['url']
+        check_call(['git', 'clone', url, REPO_DIR])
+
+    # checkout tag
+    check_call(['git', 'checkout', '-f', versions['obfs4']['tag']], cwd=REPO_DIR)
+
+    # undo all changes
+    check_call(['git', 'reset', '--hard'], cwd=REPO_DIR)
+
+    # clean all untracked files and directories (-d) from repo
+    check_call(['git', 'clean', '-dffx'], cwd=REPO_DIR)
+
+
+def build_android():
+    env = os.environ.copy()
+    env['GOARCH'] = "arm"
+    env['GOARM'] = "7"
+    build_android_arch(env, "arm-linux-androideabi", ndk_arch="arm", pie=False)
+
+    env = os.environ.copy()
+    env['GOARCH'] = "arm"
+    env['GOARM'] = "7"
+    build_android_arch(env, "arm-linux-androideabi", ndk_arch="arm", pie=True)
+
+    env = os.environ.copy()
+    env['GOARCH'] = "386"
+    build_android_arch(env, "i686-linux-android", ndk_arch="x86", pie=False)
+
+    env = os.environ.copy()
+    env['GOARCH'] = "386"
+    build_android_arch(env, "i686-linux-android", ndk_arch="x86", pie=True)
+
+
+def build_android_arch(env, tool, ndk_arch, pie):
+    toolchain = os.path.join("toolchain", ndk_arch)
+    if not os.path.isdir(toolchain):
+        toolchain_maker = os.path.join(NDK_DIR, "build", "tools", "make-standalone-toolchain.sh")
+        ex([toolchain_maker, "--arch=%s" % ndk_arch, "--install-dir=%s" % toolchain])
+
+    env['CC'] = "%s/bin/%s-clang" % (os.path.abspath(toolchain), tool)
+    env['CGO_ENABLED'] = "1"
+    env['GOOS'] = "android"
+
+    build_mode = "pie" if pie else "exe"
+
+    ex(['go', 'build', '-buildmode=%s' % build_mode, '-o', 'obfs4proxy'] + glob(SOURCE), env=env)
+
+    ex(['%s/bin/%s-strip' % (toolchain, tool), '-D', 'obfs4proxy'])
+
+    pie_suffix = '_pie' if pie else ''
+    zip_file('obfs4proxy', 'obfs4proxy_%s%s.zip' % (ndk_arch, pie_suffix))
+    os.remove('obfs4proxy')
+
+
+def build_linux():
+    ex(['go', 'build', '-o', 'obfs4proxy'] + glob(SOURCE))
+    ex(['strip', '-D', 'obfs4proxy'])
+    zip_file('obfs4proxy', 'obfs4proxy_linux-x86_64.zip')
+    os.remove('obfs4proxy')
+
+
+def get_source_files():
+    files = []
+    for file_name in glob(SOURCE):
+        print(file_name)
+    return files
+
+
+if __name__ == "__main__":
+    main()

utils.py

+import hashlib
+import json
+import sys
+from collections import OrderedDict
+from subprocess import check_call
+
+REPO_DIR = 'tor-android'
+
+
+def get_version():
+    if len(sys.argv) > 2:
+        fail("Usage: %s [version tag]" % sys.argv[0])
+    return sys.argv[1] if len(sys.argv) > 1 else None
+
+
+def get_build_versions(tag):
+    # load versions and their dependencies
+    with open('versions.json', 'r') as f:
+        versions = json.load(f, object_pairs_hook=OrderedDict)
+
+    if tag is None:
+        # take top-most version
+        tag = next(iter(versions))
+    return versions[tag]
+
+
+def ex(args, env=None):
+    print("+ %s" % " ".join(args))
+    check_call(args, env=env)
+
+
+def fail(msg=""):
+    sys.stderr.write("Error: %s\n" % msg)
+    sys.exit(1)
+
+
+def get_sha256(filename, block_size=65536):
+    sha256 = hashlib.sha256()
+    with open(filename, 'rb') as f:
+        for block in iter(lambda: f.read(block_size), b''):
+            sha256.update(block)
+    return sha256.hexdigest()
+
+
+def zip_file(file_name, zip_name):
+    ex(['touch', '--no-dereference', '-t', '197001010000.00', file_name])
+    ex(['zip', '-X', zip_name, file_name])

versions.json

+{
+  "0.0.7": {
+    "obfs4": {
+      "url": "https://git.torproject.org/pluggable-transports/obfs4.git",
+      "got-get": "git.torproject.org/pluggable-transports/obfs4.git/obfs4proxy",
+      "tag": "obfs4proxy-0.0.7"
+    },
+    "ndk": {
+      "url": "https://dl.google.com/android/repository/android-ndk-r18-linux-x86_64.zip",
+      "revision": "18.0.5002713",
+      "sha256": "c413dd014edc37f822d0dc88fabc05b64232d07d5c6e9345224e47073fdf140b"
+    }
+  }
+}