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mse: Reuse writer write buffer

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This commit is contained in:
Matt Joiner 2017-09-13 01:00:43 +10:00
parent f1d292203e
commit 7e056f7753
1 changed files with 19 additions and 7 deletions
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26
mse/mse.go
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@ -116,17 +116,29 @@ func newCipherReader(c *rc4.Cipher, r io.Reader) io.Reader {
type cipherWriter struct {
c *rc4.Cipher
w io.Writer
b []byte
}
func (cr *cipherWriter) Write(b []byte) (n int, err error) {
be := make([]byte, len(b))
cr.c.XORKeyStream(be, b)
n, err = cr.w.Write(be)
if n != len(be) {
be := func() []byte {
if len(cr.b) < len(b) {
return make([]byte, len(b))
} else {
ret := cr.b
cr.b = nil
return ret
}
}()
cr.c.XORKeyStream(be[:], b)
n, err = cr.w.Write(be[:len(b)])
if n != len(b) {
// The cipher will have advanced beyond the callers stream position.
// We can't use the cipher anymore.
cr.c = nil
}
if len(be) > len(cr.b) {
cr.b = be
}
return
}
@ -390,7 +402,7 @@ func (h *handshake) initerSteps() (ret io.ReadWriter, err error) {
if err != nil {
return
}
ret = readWriter{r, &cipherWriter{e, h.conn}}
ret = readWriter{r, &cipherWriter{e, h.conn, nil}}
return
}
@ -449,7 +461,7 @@ func (h *handshake) receiverSteps() (ret io.ReadWriter, err error) {
unmarshal(r, h.ia)
}
buf := &bytes.Buffer{}
w := cipherWriter{h.newEncrypt(false), buf}
w := cipherWriter{h.newEncrypt(false), buf, nil}
padLen = uint16(newPadLen())
err = marshal(&w, &vc, uint32(cryptoMethodRC4), padLen, zeroPad[:padLen])
if err != nil {
@ -459,7 +471,7 @@ func (h *handshake) receiverSteps() (ret io.ReadWriter, err error) {
if err != nil {
return
}
ret = readWriter{io.MultiReader(bytes.NewReader(h.ia), r), &cipherWriter{w.c, h.conn}}
ret = readWriter{io.MultiReader(bytes.NewReader(h.ia), r), &cipherWriter{w.c, h.conn, nil}}
return
}