TUN-4597: Add a QUIC server skeleton

- Added a QUIC server to accept streams
- Unit test for this server also tests ALPN
- Temporary echo capability for HTTP ConnectionType

vendor/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_generic.go

@@ -0,0 +1,81 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package chacha20poly1305
+
+import (
+	"encoding/binary"
+
+	"golang.org/x/crypto/chacha20"
+	"golang.org/x/crypto/internal/subtle"
+	"golang.org/x/crypto/poly1305"
+)
+
+func writeWithPadding(p *poly1305.MAC, b []byte) {
+	p.Write(b)
+	if rem := len(b) % 16; rem != 0 {
+		var buf [16]byte
+		padLen := 16 - rem
+		p.Write(buf[:padLen])
+	}
+}
+
+func writeUint64(p *poly1305.MAC, n int) {
+	var buf [8]byte
+	binary.LittleEndian.PutUint64(buf[:], uint64(n))
+	p.Write(buf[:])
+}
+
+func (c *chacha20poly1305) sealGeneric(dst, nonce, plaintext, additionalData []byte) []byte {
+	ret, out := sliceForAppend(dst, len(plaintext)+poly1305.TagSize)
+	ciphertext, tag := out[:len(plaintext)], out[len(plaintext):]
+	if subtle.InexactOverlap(out, plaintext) {
+		panic("chacha20poly1305: invalid buffer overlap")
+	}
+
+	var polyKey [32]byte
+	s, _ := chacha20.NewUnauthenticatedCipher(c.key[:], nonce)
+	s.XORKeyStream(polyKey[:], polyKey[:])
+	s.SetCounter(1) // set the counter to 1, skipping 32 bytes
+	s.XORKeyStream(ciphertext, plaintext)
+
+	p := poly1305.New(&polyKey)
+	writeWithPadding(p, additionalData)
+	writeWithPadding(p, ciphertext)
+	writeUint64(p, len(additionalData))
+	writeUint64(p, len(plaintext))
+	p.Sum(tag[:0])
+
+	return ret
+}
+
+func (c *chacha20poly1305) openGeneric(dst, nonce, ciphertext, additionalData []byte) ([]byte, error) {
+	tag := ciphertext[len(ciphertext)-16:]
+	ciphertext = ciphertext[:len(ciphertext)-16]
+
+	var polyKey [32]byte
+	s, _ := chacha20.NewUnauthenticatedCipher(c.key[:], nonce)
+	s.XORKeyStream(polyKey[:], polyKey[:])
+	s.SetCounter(1) // set the counter to 1, skipping 32 bytes
+
+	p := poly1305.New(&polyKey)
+	writeWithPadding(p, additionalData)
+	writeWithPadding(p, ciphertext)
+	writeUint64(p, len(additionalData))
+	writeUint64(p, len(ciphertext))
+
+	ret, out := sliceForAppend(dst, len(ciphertext))
+	if subtle.InexactOverlap(out, ciphertext) {
+		panic("chacha20poly1305: invalid buffer overlap")
+	}
+	if !p.Verify(tag) {
+		for i := range out {
+			out[i] = 0
+		}
+		return nil, errOpen
+	}
+
+	s.XORKeyStream(out, ciphertext)
+	return ret, nil
+}