crypto/tls (part 1)

Rather than drop everything into a single, huge review, I've included
some simple bits of code here.

R=rsc
CC=go-dev
http://go/go-review/1016029

src/pkg/crypto/tls/common.go

@@ -0,0 +1,123 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package tls
+
+import (
+	"crypto/rsa";
+	"io";
+	"os";
+)
+
+const (
+	// maxTLSCiphertext is the maximum length of a plaintext payload.
+	maxTLSPlaintext	= 16384;
+	// maxTLSCiphertext is the maximum length payload after compression and encryption.
+	maxTLSCiphertext	= 16384+2048;
+	// maxHandshakeMsg is the largest single handshake message that we'll buffer.
+	maxHandshakeMsg	= 65536;
+)
+
+
+// TLS record types.
+type recordType uint8
+
+const (
+	recordTypeChangeCipherSpec	recordType	= 20;
+	recordTypeAlert			recordType	= 21;
+	recordTypeHandshake		recordType	= 22;
+	recordTypeApplicationData	recordType	= 23;
+)
+
+// TLS handshake message types.
+const (
+	typeClientHello		uint8	= 1;
+	typeServerHello		uint8	= 2;
+	typeCertificate		uint8	= 11;
+	typeServerHelloDone	uint8	= 14;
+	typeClientKeyExchange	uint8	= 16;
+	typeFinished		uint8	= 20;
+)
+
+// TLS cipher suites.
+var (
+	TLS_RSA_WITH_RC4_128_SHA uint16 = 5;
+)
+
+// TLS compression types.
+var (
+	compressionNone uint8 = 0;
+)
+
+type ConnectionState struct {
+	HandshakeComplete	bool;
+	CipherSuite		string;
+	Error			alertType;
+}
+
+// A Config structure is used to configure a TLS client or server. After one
+// has been passed to a TLS function it must not be modified.
+type Config struct {
+	// Rand provides the source of entropy for nonces and RSA blinding.
+	Rand	io.Reader;
+	// Time returns the current time as the number of seconds since the epoch.
+	Time		func() int64;
+	Certificates	[]Certificate;
+}
+
+type Certificate struct {
+	Certificate	[][]byte;
+	PrivateKey	*rsa.PrivateKey;
+}
+
+// A TLS record.
+type record struct {
+	contentType	recordType;
+	major, minor	uint8;
+	payload		[]byte;
+}
+
+type handshakeMessage interface {
+	marshal() []byte;
+}
+
+type encryptor interface {
+	// XORKeyStream xors the contents of the slice with bytes from the key stream.
+	XORKeyStream(buf []byte);
+}
+
+// mutualVersion returns the protocol version to use given the advertised
+// version of the peer.
+func mutualVersion(theirMajor, theirMinor uint8) (major, minor uint8, ok bool) {
+	// We don't deal with peers < TLS 1.0 (aka version 3.1).
+	if theirMajor < 3 || theirMajor == 3 && theirMinor < 1 {
+		return 0, 0, false;
+	}
+	major = 3;
+	minor = 2;
+	if theirMinor < minor {
+		minor = theirMinor;
+	}
+	ok = true;
+	return;
+}
+
+// A nop implements the NULL encryption and MAC algorithms.
+type nop struct{}
+
+func (nop) XORKeyStream(buf []byte) {}
+
+func (nop) Write(buf []byte) (int, os.Error) {
+	return len(buf), nil;
+}
+
+func (nop) Sum() []byte {
+	return nil;
+}
+
+func (nop) Reset() {}
+
+func (nop) Size() int {
+	return 0;
+}