Don't use modules

Feel free to revert this if you have a strong feeling about it. But so
far as I can see, it adds a lot of complexity for basically no upsides.

cookie.go

@@ -3,7 +3,6 @@ package main
 import (
 	"crypto/hmac"
 	"crypto/rand"
-	"git.zx2c4.com/wireguard-go/internal/xchacha20poly1305"
 	"golang.org/x/crypto/blake2s"
 	"golang.org/x/crypto/chacha20poly1305"
 	"sync"
@@ -158,7 +157,7 @@ func (st *CookieChecker) CreateReply(
 		return nil, err
 	}
 
-	xchacha20poly1305.Encrypt(
+	XChaCha20Poly1305Encrypt(
 		reply.Cookie[:0],
 		&reply.Nonce,
 		cookie[:],
@@ -202,7 +201,7 @@ func (st *CookieGenerator) ConsumeReply(msg *MessageCookieReply) bool {
 
 	var cookie [blake2s.Size128]byte
 
-	_, err := xchacha20poly1305.Decrypt(
+	_, err := XChaCha20Poly1305Decrypt(
 		cookie[:0],
 		&msg.Nonce,
 		msg.Cookie[:],

device.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"git.zx2c4.com/wireguard-go/internal/ratelimiter"
 	"runtime"
 	"sync"
 	"sync/atomic"
@@ -51,7 +50,7 @@ type Device struct {
 
 	rate struct {
 		underLoadUntil atomic.Value
-		limiter        ratelimiter.Ratelimiter
+		limiter        Ratelimiter
 	}
 
 	pool struct {

noise-protocol.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"errors"
-	"git.zx2c4.com/wireguard-go/internal/tai64n"
 	"golang.org/x/crypto/blake2s"
 	"golang.org/x/crypto/chacha20poly1305"
 	"golang.org/x/crypto/poly1305"
@@ -59,7 +58,7 @@ type MessageInitiation struct {
 	Sender    uint32
 	Ephemeral NoisePublicKey
 	Static    [NoisePublicKeySize + poly1305.TagSize]byte
-	Timestamp [tai64n.TimestampSize + poly1305.TagSize]byte
+	Timestamp [TimestampSize + poly1305.TagSize]byte
 	MAC1      [blake2s.Size128]byte
 	MAC2      [blake2s.Size128]byte
 }
@@ -100,7 +99,7 @@ type Handshake struct {
 	remoteStatic              NoisePublicKey           // long term key
 	remoteEphemeral           NoisePublicKey           // ephemeral public key
 	precomputedStaticStatic   [NoisePublicKeySize]byte // precomputed shared secret
-	lastTimestamp             tai64n.Timestamp
+	lastTimestamp             Timestamp
 	lastInitiationConsumption time.Time
 }
 
@@ -207,7 +206,7 @@ func (device *Device) CreateMessageInitiation(peer *Peer) (*MessageInitiation, e
 
 	// encrypt timestamp
 
-	timestamp := tai64n.Now()
+	timestamp := TimestampNow()
 	func() {
 		var key [chacha20poly1305.KeySize]byte
 		KDF2(
@@ -272,7 +271,7 @@ func (device *Device) ConsumeMessageInitiation(msg *MessageInitiation) *Peer {
 
 	// verify identity
 
-	var timestamp tai64n.Timestamp
+	var timestamp Timestamp
 	var key [chacha20poly1305.KeySize]byte
 
 	handshake.mutex.RLock()

ratelimiter.go

@@ -1,4 +1,4 @@
-package ratelimiter
+package main
 
 /* Copyright (C) 2015-2017 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. */
 

ratelimiter_test.go

@@ -1,4 +1,4 @@
-package ratelimiter
+package main
 
 import (
 	"net"

tai64n.go

@@ -1,4 +1,4 @@
-package tai64n
+package main
 
 import (
 	"bytes"
@@ -11,7 +11,7 @@ const base = uint64(4611686018427387914)
 
 type Timestamp [TimestampSize]byte
 
-func Now() Timestamp {
+func TimestampNow() Timestamp {
 	var tai64n Timestamp
 	now := time.Now()
 	secs := base + uint64(now.Unix())

tai64n_test.go

@@ -1,4 +1,4 @@
-package tai64n
+package main
 
 import (
 	"testing"
@@ -9,10 +9,10 @@ import (
  * as used by WireGuard.
  */
 func TestMonotonic(t *testing.T) {
-	old := Now()
+	old := TimestampNow()
 	for i := 0; i < 10000; i++ {
 		time.Sleep(time.Nanosecond)
-		next := Now()
+		next := TimestampNow()
 		if !next.After(old) {
 			t.Error("TAI64N, not monotonically increasing on nano-second scale")
 		}

xchacha20.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a license that can be
 // found in the LICENSE file.
 
-package xchacha20poly1305
+package main
 
 import (
 	"encoding/binary"
@@ -138,7 +138,7 @@ func hChaCha20(out *[32]byte, nonce []byte, key *[32]byte) {
 	binary.LittleEndian.PutUint32(out[28:], v15)
 }
 
-func Encrypt(
+func XChaCha20Poly1305Encrypt(
 	dst []byte,
 	nonceFull *[24]byte,
 	plaintext []byte,
@@ -153,7 +153,7 @@ func Encrypt(
 	return aead.Seal(dst, nonce[:], plaintext, additionalData)
 }
 
-func Decrypt(
+func XChaCha20Poly1305Decrypt(
 	dst []byte,
 	nonceFull *[24]byte,
 	plaintext []byte,

xchacha20_test.go

@@ -1,4 +1,4 @@
-package xchacha20poly1305
+package main
 
 import (
 	"encoding/hex"
@@ -60,7 +60,7 @@ func TestXChaCha20(t *testing.T) {
 
 			// test encryption
 
-			ct := Encrypt(
+			ct := XChaCha20Poly1305Encrypt(
 				nil,
 				&nonceArray,
 				pt,
@@ -74,7 +74,7 @@ func TestXChaCha20(t *testing.T) {
 
 			// test decryption
 
-			ptp, err := Decrypt(
+			ptp, err := XChaCha20Poly1305Decrypt(
 				nil,
 				&nonceArray,
 				ct,