First stab at Go bridge

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

.gitmodules

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+[submodule "wireguard-go"]
+	path = wireguard-go
+	url = https://git.zx2c4.com/wireguard-go

wireguard-go

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+Subproject commit 0ba551807fcd0d33c6ad80842b71c8de42c2da55

wireguard-go-bridge/Makefile

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+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+
+FILES := $(filter-out %/main.go,$(wildcard ../wireguard-go/*/*.go) $(wildcard ../wireguard-go/*.go))
+
+# CLANG_FLAGS := --target=$(ANDROID_LLVM_TRIPLE) --gcc-toolchain=$(ANDROID_TOOLCHAIN_ROOT) --sysroot=$(ANDROID_SYSROOT)
+# export CGO_CFLAGS := $(CLANG_FLAGS) $(CFLAGS)
+# export CGO_LDFLAGS := $(CLANG_FLAGS) $(LDFLAGS)
+# export CC := $(ANDROID_C_COMPILER)
+# export GOARCH := $(NDK_GO_ARCH_MAP_$(ANDROID_ARCH_NAME))
+export GOOS := darwin
+export CGO_ENABLED := 1
+
+default: example
+
+libwg-go.so: $(FILES) src/git.zx2c4.com/wireguard-go/api-ios.go src/git.zx2c4.com/wireguard-go/tun/tun_ios.go
+	find . -name '*.go' -type l -delete
+	find . -type d -empty -delete
+	mkdir -p $(subst ../wireguard-go/,./src/git.zx2c4.com/wireguard-go/,$(dir $(FILES)))
+	$(foreach FILE,$(FILES),ln -sf $(abspath $(FILE)) $(subst ../wireguard-go/,./src/git.zx2c4.com/wireguard-go/,$(dir $(FILE)))$(file $(FILE));)
+	GOPATH=$(PWD) go get -v -d git.zx2c4.com/wireguard-go
+	GOPATH=$(PWD) go build -tags ios -v -o libwg-go.so -buildmode c-shared git.zx2c4.com/wireguard-go
+	@rm -f libwg-go.h
+
+example: example.c libwg-go.so
+	$(CC) -L. -lwg-go -o example example.c
+
+clean:
+	rm -f libwg-go.so test
+
+.PHONY: clean default

wireguard-go-bridge/example.c

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+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#include "wireguard.h"
+#include <stdio.h>
+#include <stdbool.h>
+#include <unistd.h>
+
+static struct {
+	int something;
+} ctx;
+
+static bool is_closed = false;
+
+ssize_t do_read(const void *ctx, const unsigned char *buf, size_t len)
+{
+	printf("Reading from instance with ctx %p into buffer %p of length %zu\n", ctx, buf, len);
+	sleep(1);
+	return is_closed ? -1 : 0;
+}
+
+ssize_t do_write(const void *ctx, const unsigned char *buf, size_t len)
+{
+	printf("Writing from instance with ctx %p into buffer %p of length %zu\n", ctx, buf, len);
+	return len;
+}
+
+void do_log(int level, const char *tag, const char *msg)
+{
+	printf("Log level %d for %s: %s", level, tag, msg);
+}
+
+int main(int argc, char *argv[])
+{
+	int handle;
+
+	printf("WireGuard Go Version %s\n", wgVersion());
+	wgSetLogger(do_log);
+	handle = wgTurnOn((gostring_t){ .p = "test", .n = 4 }, (gostring_t){ .p = "", .n = 0 }, do_read, do_write, &ctx);
+	sleep(5);
+	is_closed = true;
+	wgTurnOff(handle);
+	return 0;
+}

wireguard-go-bridge/src/git.zx2c4.com/wireguard-go/api-ios.go

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+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+package main
+
+// #include <sys/types.h>
+// static void callLogger(void *func, int level, const char *tag, const char *msg)
+// {
+// 	((void(*)(int, const char *, const char *))func)(level, tag, msg);
+// }
+import "C"
+
+import (
+	"bufio"
+	"git.zx2c4.com/wireguard-go/tun"
+	"golang.org/x/sys/unix"
+	"io/ioutil"
+	"log"
+	"math"
+	"os"
+	"os/signal"
+	"runtime"
+	"strings"
+	"unsafe"
+	"errors"
+)
+
+var loggerFunc unsafe.Pointer
+
+type CLogger struct {
+	level         C.int
+	interfaceName string
+}
+
+func (l *CLogger) Write(p []byte) (int, error) {
+	if uintptr(loggerFunc) == 0 {
+		return 0, errors.New("No logger initialized")
+	}
+	C.callLogger(loggerFunc, l.level, C.CString("WireGuard/GoBackend/"+l.interfaceName), C.CString(string(p)))
+	return len(p), nil
+}
+
+var tunnelHandles map[int32]*Device
+
+func init() {
+	roamingDisabled = true
+	tunnelHandles = make(map[int32]*Device)
+	signals := make(chan os.Signal)
+	signal.Notify(signals, unix.SIGUSR2)
+	go func() {
+		buf := make([]byte, os.Getpagesize())
+		for {
+			select {
+			case <-signals:
+				n := runtime.Stack(buf, true)
+				buf[n] = 0
+				if uintptr(loggerFunc) != 0 {
+					C.callLogger(loggerFunc, 0, C.CString("WireGuard/GoBackend/Stacktrace"), (*_Ctype_char)(unsafe.Pointer(&buf[0])))
+				}
+			}
+		}
+	}()
+}
+
+//export wgSetLogger
+func wgSetLogger(loggerFn uintptr) {
+	loggerFunc = unsafe.Pointer(loggerFn)
+}
+
+//export wgTurnOn
+func wgTurnOn(ifnameRef string, settings string, readFn uintptr, writeFn uintptr, ctx uintptr) int32 {
+	interfaceName := string([]byte(ifnameRef))
+
+	logger := &Logger{
+		Debug: log.New(&CLogger{level: 0, interfaceName: interfaceName}, "", 0),
+		Info:  log.New(&CLogger{level: 1, interfaceName: interfaceName}, "", 0),
+		Error: log.New(&CLogger{level: 2, interfaceName: interfaceName}, "", 0),
+	}
+
+	logger.Debug.Println("Debug log enabled")
+
+	tun := tun.CreateTUN(1280, unsafe.Pointer(readFn), unsafe.Pointer(writeFn), unsafe.Pointer(ctx))
+	logger.Info.Println("Attaching to interface")
+	device := NewDevice(tun, logger)
+
+	logger.Debug.Println("Interface has MTU", device.tun.mtu)
+
+	bufferedSettings := bufio.NewReadWriter(bufio.NewReader(strings.NewReader(settings)), bufio.NewWriter(ioutil.Discard))
+	setError := ipcSetOperation(device, bufferedSettings)
+	if setError != nil {
+		logger.Error.Println(setError)
+		return -1
+	}
+
+	device.Up()
+	logger.Info.Println("Device started")
+
+	var i int32
+	for i = 0; i < math.MaxInt32; i++ {
+		if _, exists := tunnelHandles[i]; !exists {
+			break
+		}
+	}
+	if i == math.MaxInt32 {
+		return -1
+	}
+	tunnelHandles[i] = device
+	return i
+}
+
+//export wgTurnOff
+func wgTurnOff(tunnelHandle int32) {
+	device, ok := tunnelHandles[tunnelHandle]
+	if !ok {
+		return
+	}
+	delete(tunnelHandles, tunnelHandle)
+	device.Close()
+}
+
+//export wgVersion
+func wgVersion() *C.char {
+	return C.CString(WireGuardGoVersion)
+}
+
+func main() {}

wireguard-go-bridge/src/git.zx2c4.com/wireguard-go/tun/tun_ios.go

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+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+package tun
+
+// #include <sys/types.h>
+// static ssize_t callFnWithCtx(const void *func, const void *ctx, const void *buffer, size_t len)
+// {
+// 	return ((ssize_t(*)(const void *, const unsigned char *, size_t))func)(ctx, buffer, len);
+// }
+import "C"
+
+import (
+	"os"
+	"syscall"
+	"unsafe"
+)
+
+type nativeTun struct {
+	events  chan TUNEvent
+	mtu     int
+	readFn  unsafe.Pointer
+	writeFn unsafe.Pointer
+	ctx     unsafe.Pointer
+}
+
+func CreateTUN(mtu int, readFn unsafe.Pointer, writeFn unsafe.Pointer, ctx unsafe.Pointer) TUNDevice {
+	tun := &nativeTun{
+		events:  make(chan TUNEvent, 10),
+		mtu:     mtu,
+		readFn:  readFn,
+		writeFn: writeFn,
+		ctx:     ctx,
+	}
+	tun.events <- TUNEventUp
+	return tun
+}
+
+func (tun *nativeTun) Name() (string, error) {
+	return "tun", nil
+}
+
+func (tun *nativeTun) File() *os.File {
+	return nil
+}
+
+func (tun *nativeTun) Events() chan TUNEvent {
+	return tun.events
+}
+
+func (tun *nativeTun) Read(buff []byte, offset int) (int, error) {
+	buff = buff[offset:]
+	ret := C.callFnWithCtx(tun.readFn, tun.ctx, unsafe.Pointer(&buff[0]), C.size_t(len(buff)))
+	if ret < 0 {
+		return 0, syscall.Errno(-ret)
+	}
+	return int(ret), nil
+}
+
+func (tun *nativeTun) Write(buff []byte, offset int) (int, error) {
+	buff = buff[offset:]
+	ret := C.callFnWithCtx(tun.writeFn, tun.ctx, unsafe.Pointer(&buff[0]), C.size_t(len(buff)))
+	if ret < 0 {
+		return 0, syscall.Errno(-ret)
+	}
+	return int(ret), nil
+}
+
+func (tun *nativeTun) Close() error {
+	if tun.events != nil {
+		close(tun.events)
+	}
+	return nil
+}
+
+func (tun *nativeTun) setMTU(n int) error {
+	tun.mtu = n
+	return nil
+}
+
+func (tun *nativeTun) MTU() (int, error) {
+	return tun.mtu, nil
+}

wireguard-go-bridge/wireguard.h

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+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#ifndef WIREGUARD_H
+#define WIREGUARD_H
+
+#include <sys/types.h>
+
+typedef struct { const char *p; size_t n; } gostring_t;
+typedef ssize_t(*read_write_fn_t)(const void *ctx, const unsigned char *buf, size_t len);
+typedef void(*logger_fn_t)(int level, const char *tag, const char *msg);
+extern void wgSetLogger(logger_fn_t logger_fn);
+extern int wgTurnOn(gostring_t ifname, gostring_t settings, read_write_fn_t read_fn, read_write_fn_t write_fn, void *ctx);
+extern void wgTurnOff(int handle);
+extern char *wgVersion();
+
+#endif