113 lines
3 KiB
Go
113 lines
3 KiB
Go
package shadowaead
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import (
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"crypto/rand"
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"errors"
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"io"
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"net"
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N "github.com/metacubex/mihomo/common/net"
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"github.com/metacubex/mihomo/common/pool"
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)
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// ErrShortPacket means that the packet is too short for a valid encrypted packet.
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var ErrShortPacket = errors.New("short packet")
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var _zerononce [128]byte // read-only. 128 bytes is more than enough.
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// Pack encrypts plaintext using Cipher with a randomly generated salt and
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// returns a slice of dst containing the encrypted packet and any error occurred.
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// Ensure len(dst) >= ciph.SaltSize() + len(plaintext) + aead.Overhead().
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func Pack(dst, plaintext []byte, ciph Cipher) ([]byte, error) {
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saltSize := ciph.SaltSize()
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salt := dst[:saltSize]
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if _, err := rand.Read(salt); err != nil {
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return nil, err
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}
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aead, err := ciph.Encrypter(salt)
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if err != nil {
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return nil, err
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}
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if len(dst) < saltSize+len(plaintext)+aead.Overhead() {
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return nil, io.ErrShortBuffer
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}
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b := aead.Seal(dst[saltSize:saltSize], _zerononce[:aead.NonceSize()], plaintext, nil)
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return dst[:saltSize+len(b)], nil
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}
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// Unpack decrypts pkt using Cipher and returns a slice of dst containing the decrypted payload and any error occurred.
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// Ensure len(dst) >= len(pkt) - aead.SaltSize() - aead.Overhead().
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func Unpack(dst, pkt []byte, ciph Cipher) ([]byte, error) {
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saltSize := ciph.SaltSize()
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if len(pkt) < saltSize {
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return nil, ErrShortPacket
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}
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salt := pkt[:saltSize]
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aead, err := ciph.Decrypter(salt)
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if err != nil {
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return nil, err
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}
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if len(pkt) < saltSize+aead.Overhead() {
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return nil, ErrShortPacket
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}
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if saltSize+len(dst)+aead.Overhead() < len(pkt) {
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return nil, io.ErrShortBuffer
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}
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b, err := aead.Open(dst[:0], _zerononce[:aead.NonceSize()], pkt[saltSize:], nil)
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return b, err
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}
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type PacketConn struct {
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N.EnhancePacketConn
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Cipher
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}
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const maxPacketSize = 64 * 1024
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// NewPacketConn wraps an N.EnhancePacketConn with cipher
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func NewPacketConn(c N.EnhancePacketConn, ciph Cipher) *PacketConn {
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return &PacketConn{EnhancePacketConn: c, Cipher: ciph}
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}
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// WriteTo encrypts b and write to addr using the embedded PacketConn.
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func (c *PacketConn) WriteTo(b []byte, addr net.Addr) (int, error) {
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buf := pool.Get(maxPacketSize)
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defer pool.Put(buf)
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buf, err := Pack(buf, b, c)
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if err != nil {
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return 0, err
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}
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_, err = c.EnhancePacketConn.WriteTo(buf, addr)
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return len(b), err
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}
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// ReadFrom reads from the embedded PacketConn and decrypts into b.
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func (c *PacketConn) ReadFrom(b []byte) (int, net.Addr, error) {
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n, addr, err := c.EnhancePacketConn.ReadFrom(b)
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if err != nil {
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return n, addr, err
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}
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bb, err := Unpack(b[c.Cipher.SaltSize():], b[:n], c)
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if err != nil {
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return n, addr, err
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}
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copy(b, bb)
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return len(bb), addr, err
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}
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func (c *PacketConn) WaitReadFrom() (data []byte, put func(), addr net.Addr, err error) {
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data, put, addr, err = c.EnhancePacketConn.WaitReadFrom()
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if err != nil {
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return
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}
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data, err = Unpack(data[c.Cipher.SaltSize():], data, c)
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if err != nil {
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if put != nil {
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put()
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}
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data = nil
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put = nil
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return
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}
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return
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}
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