Add hysteria and acme TLS certificate issuer (#18)

* Add hysteria client/server
* Add acme TLS certificate issuer

transport/hysteria/xplus.go

@@ -0,0 +1,119 @@
+package hysteria
+
+import (
+	"crypto/sha256"
+	"math/rand"
+	"net"
+	"sync"
+	"time"
+
+	"github.com/sagernet/sing/common"
+	"github.com/sagernet/sing/common/buf"
+	"github.com/sagernet/sing/common/bufio"
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+)
+
+const xplusSaltLen = 16
+
+var errInalidPacket = E.New("invalid packet")
+
+func NewXPlusPacketConn(conn net.PacketConn, key []byte) net.PacketConn {
+	vectorisedWriter, isVectorised := bufio.CreateVectorisedPacketWriter(conn)
+	if isVectorised {
+		return &VectorisedXPlusConn{
+			XPlusPacketConn: XPlusPacketConn{
+				PacketConn: conn,
+				key:        key,
+				rand:       rand.New(rand.NewSource(time.Now().UnixNano())),
+			},
+			writer: vectorisedWriter,
+		}
+	} else {
+		return &XPlusPacketConn{
+			PacketConn: conn,
+			key:        key,
+			rand:       rand.New(rand.NewSource(time.Now().UnixNano())),
+		}
+	}
+}
+
+type XPlusPacketConn struct {
+	net.PacketConn
+	key        []byte
+	randAccess sync.Mutex
+	rand       *rand.Rand
+}
+
+func (c *XPlusPacketConn) ReadFrom(p []byte) (n int, addr net.Addr, err error) {
+	n, addr, err = c.PacketConn.ReadFrom(p)
+	if err != nil {
+		return
+	} else if n < xplusSaltLen {
+		return 0, nil, errInalidPacket
+	}
+	key := sha256.Sum256(append(c.key, p[:xplusSaltLen]...))
+	for i := range p[xplusSaltLen:] {
+		p[i] = p[xplusSaltLen+i] ^ key[i%sha256.Size]
+	}
+	n -= xplusSaltLen
+	return
+}
+
+func (c *XPlusPacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
+	// can't use unsafe buffer on WriteTo
+	buffer := buf.NewSize(len(p) + xplusSaltLen)
+	defer buffer.Release()
+	salt := buffer.Extend(xplusSaltLen)
+	c.randAccess.Lock()
+	_, _ = c.rand.Read(salt)
+	c.randAccess.Unlock()
+	key := sha256.Sum256(append(c.key, salt...))
+	for i := range p {
+		common.Must(buffer.WriteByte(p[i] ^ key[i%sha256.Size]))
+	}
+	return c.PacketConn.WriteTo(buffer.Bytes(), addr)
+}
+
+func (c *XPlusPacketConn) Upstream() any {
+	return c.PacketConn
+}
+
+type VectorisedXPlusConn struct {
+	XPlusPacketConn
+	writer N.VectorisedPacketWriter
+}
+
+func (c *VectorisedXPlusConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
+	header := buf.NewSize(xplusSaltLen)
+	defer header.Release()
+	salt := header.Extend(xplusSaltLen)
+	c.randAccess.Lock()
+	_, _ = c.rand.Read(salt)
+	c.randAccess.Unlock()
+	key := sha256.Sum256(append(c.key, salt...))
+	for i := range p {
+		p[i] ^= key[i%sha256.Size]
+	}
+	return bufio.WriteVectorisedPacket(c.writer, [][]byte{header.Bytes(), p}, M.SocksaddrFromNet(addr))
+}
+
+func (c *VectorisedXPlusConn) WriteVectorisedPacket(buffers []*buf.Buffer, destination M.Socksaddr) error {
+	header := buf.NewSize(xplusSaltLen)
+	salt := header.Extend(xplusSaltLen)
+	c.randAccess.Lock()
+	_, _ = c.rand.Read(salt)
+	c.randAccess.Unlock()
+	key := sha256.Sum256(append(c.key, salt...))
+	var index int
+	for _, buffer := range buffers {
+		data := buffer.Bytes()
+		for i := range data {
+			data[i] ^= key[index%sha256.Size]
+			index++
+		}
+	}
+	buffers = append([]*buf.Buffer{header}, buffers...)
+	return c.writer.WriteVectorisedPacket(buffers, destination)
+}