initial commit

internal/util/quic/conn.go

@@ -0,0 +1,90 @@
+package quic
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"errors"
+	"io"
+	"net"
+)
+
+type cipherConn struct {
+	net.PacketConn
+	key []byte
+}
+
+func CipherPacketConn(conn net.PacketConn, key []byte) net.PacketConn {
+	return &cipherConn{
+		PacketConn: conn,
+		key:        key,
+	}
+}
+
+func (conn *cipherConn) ReadFrom(data []byte) (n int, addr net.Addr, err error) {
+	n, addr, err = conn.PacketConn.ReadFrom(data)
+	if err != nil {
+		return
+	}
+	b, err := conn.decrypt(data[:n])
+	if err != nil {
+		return
+	}
+
+	copy(data, b)
+
+	return len(b), addr, nil
+}
+
+func (conn *cipherConn) WriteTo(data []byte, addr net.Addr) (n int, err error) {
+	b, err := conn.encrypt(data)
+	if err != nil {
+		return
+	}
+
+	_, err = conn.PacketConn.WriteTo(b, addr)
+	if err != nil {
+		return
+	}
+
+	return len(b), nil
+}
+
+func (conn *cipherConn) encrypt(data []byte) ([]byte, error) {
+	c, err := aes.NewCipher(conn.key)
+	if err != nil {
+		return nil, err
+	}
+
+	gcm, err := cipher.NewGCM(c)
+	if err != nil {
+		return nil, err
+	}
+
+	nonce := make([]byte, gcm.NonceSize())
+	if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
+		return nil, err
+	}
+
+	return gcm.Seal(nonce, nonce, data, nil), nil
+}
+
+func (conn *cipherConn) decrypt(data []byte) ([]byte, error) {
+	c, err := aes.NewCipher(conn.key)
+	if err != nil {
+		return nil, err
+	}
+
+	gcm, err := cipher.NewGCM(c)
+	if err != nil {
+		return nil, err
+	}
+
+	nonceSize := gcm.NonceSize()
+	if len(data) < nonceSize {
+		return nil, errors.New("ciphertext too short")
+	}
+
+	nonce, ciphertext := data[:nonceSize], data[nonceSize:]
+	return gcm.Open(nil, nonce, ciphertext, nil)
+}