Add a []byte argument to hash.Hash to allow an allocation to be saved.

This is the result of running `gofix -r hashsum` over the tree, changing
the hash function implementations by hand and then fixing a couple of
instances where gofix didn't catch something.

The changed implementations are as simple as possible while still
working: I'm not trying to optimise in this CL.

R=rsc, cw, rogpeppe
CC=golang-dev
https://golang.org/cl/5448065

cipher_suites.go

@@ -127,13 +127,13 @@ func (s ssl30MAC) MAC(seq, record []byte) []byte {
 	s.h.Write(record[:1])
 	s.h.Write(record[3:5])
 	s.h.Write(record[recordHeaderLen:])
-	digest := s.h.Sum()
+	digest := s.h.Sum(nil)
 
 	s.h.Reset()
 	s.h.Write(s.key)
 	s.h.Write(ssl30Pad2[:padLength])
 	s.h.Write(digest)
-	return s.h.Sum()
+	return s.h.Sum(nil)
 }
 
 // tls10MAC implements the TLS 1.0 MAC function. RFC 2246, section 6.2.3.
@@ -149,7 +149,7 @@ func (s tls10MAC) MAC(seq, record []byte) []byte {
 	s.h.Reset()
 	s.h.Write(seq)
 	s.h.Write(record)
-	return s.h.Sum()
+	return s.h.Sum(nil)
 }
 
 func rsaKA() keyAgreement {

handshake_client.go

@@ -232,8 +232,8 @@ func (c *Conn) clientHandshake() error {
 	if cert != nil {
 		certVerify := new(certificateVerifyMsg)
 		var digest [36]byte
-		copy(digest[0:16], finishedHash.serverMD5.Sum())
-		copy(digest[16:36], finishedHash.serverSHA1.Sum())
+		copy(digest[0:16], finishedHash.serverMD5.Sum(nil))
+		copy(digest[16:36], finishedHash.serverSHA1.Sum(nil))
 		signed, err := rsa.SignPKCS1v15(c.config.rand(), c.config.Certificates[0].PrivateKey, crypto.MD5SHA1, digest[0:])
 		if err != nil {
 			return c.sendAlert(alertInternalError)

handshake_server.go

@@ -235,8 +235,8 @@ FindCipherSuite:
 		}
 
 		digest := make([]byte, 36)
-		copy(digest[0:16], finishedHash.serverMD5.Sum())
-		copy(digest[16:36], finishedHash.serverSHA1.Sum())
+		copy(digest[0:16], finishedHash.serverMD5.Sum(nil))
+		copy(digest[16:36], finishedHash.serverSHA1.Sum(nil))
 		err = rsa.VerifyPKCS1v15(pub, crypto.MD5SHA1, digest, certVerify.signature)
 		if err != nil {
 			c.sendAlert(alertBadCertificate)

key_agreement.go

@@ -90,13 +90,13 @@ func md5SHA1Hash(slices ...[]byte) []byte {
 	for _, slice := range slices {
 		hmd5.Write(slice)
 	}
-	copy(md5sha1, hmd5.Sum())
+	copy(md5sha1, hmd5.Sum(nil))
 
 	hsha1 := sha1.New()
 	for _, slice := range slices {
 		hsha1.Write(slice)
 	}
-	copy(md5sha1[md5.Size:], hsha1.Sum())
+	copy(md5sha1[md5.Size:], hsha1.Sum(nil))
 	return md5sha1
 }
 

prf.go

@@ -22,14 +22,14 @@ func splitPreMasterSecret(secret []byte) (s1, s2 []byte) {
 func pHash(result, secret, seed []byte, hash func() hash.Hash) {
 	h := hmac.New(hash, secret)
 	h.Write(seed)
-	a := h.Sum()
+	a := h.Sum(nil)
 
 	j := 0
 	for j < len(result) {
 		h.Reset()
 		h.Write(a)
 		h.Write(seed)
-		b := h.Sum()
+		b := h.Sum(nil)
 		todo := len(b)
 		if j+todo > len(result) {
 			todo = len(result) - j
@@ -39,7 +39,7 @@ func pHash(result, secret, seed []byte, hash func() hash.Hash) {
 
 		h.Reset()
 		h.Write(a)
-		a = h.Sum()
+		a = h.Sum(nil)
 	}
 }
 
@@ -84,13 +84,13 @@ func pRF30(result, secret, label, seed []byte) {
 		hashSHA1.Write(b[:i+1])
 		hashSHA1.Write(secret)
 		hashSHA1.Write(seed)
-		digest := hashSHA1.Sum()
+		digest := hashSHA1.Sum(nil)
 
 		hashMD5.Reset()
 		hashMD5.Write(secret)
 		hashMD5.Write(digest)
 
-		done += copy(result[done:], hashMD5.Sum())
+		done += copy(result[done:], hashMD5.Sum(nil))
 		i++
 	}
 }
@@ -182,24 +182,24 @@ func finishedSum30(md5, sha1 hash.Hash, masterSecret []byte, magic [4]byte) []by
 	md5.Write(magic[:])
 	md5.Write(masterSecret)
 	md5.Write(ssl30Pad1[:])
-	md5Digest := md5.Sum()
+	md5Digest := md5.Sum(nil)
 
 	md5.Reset()
 	md5.Write(masterSecret)
 	md5.Write(ssl30Pad2[:])
 	md5.Write(md5Digest)
-	md5Digest = md5.Sum()
+	md5Digest = md5.Sum(nil)
 
 	sha1.Write(magic[:])
 	sha1.Write(masterSecret)
 	sha1.Write(ssl30Pad1[:40])
-	sha1Digest := sha1.Sum()
+	sha1Digest := sha1.Sum(nil)
 
 	sha1.Reset()
 	sha1.Write(masterSecret)
 	sha1.Write(ssl30Pad2[:40])
 	sha1.Write(sha1Digest)
-	sha1Digest = sha1.Sum()
+	sha1Digest = sha1.Sum(nil)
 
 	ret := make([]byte, len(md5Digest)+len(sha1Digest))
 	copy(ret, md5Digest)
@@ -217,8 +217,8 @@ func (h finishedHash) clientSum(masterSecret []byte) []byte {
 		return finishedSum30(h.clientMD5, h.clientSHA1, masterSecret, ssl3ClientFinishedMagic)
 	}
 
-	md5 := h.clientMD5.Sum()
-	sha1 := h.clientSHA1.Sum()
+	md5 := h.clientMD5.Sum(nil)
+	sha1 := h.clientSHA1.Sum(nil)
 	return finishedSum10(md5, sha1, clientFinishedLabel, masterSecret)
 }
 
@@ -229,7 +229,7 @@ func (h finishedHash) serverSum(masterSecret []byte) []byte {
 		return finishedSum30(h.serverMD5, h.serverSHA1, masterSecret, ssl3ServerFinishedMagic)
 	}
 
-	md5 := h.serverMD5.Sum()
-	sha1 := h.serverSHA1.Sum()
+	md5 := h.serverMD5.Sum(nil)
+	sha1 := h.serverSHA1.Sum(nil)
 	return finishedSum10(md5, sha1, serverFinishedLabel, masterSecret)
 }