go.crypto: initial code

Manual edits to README.
Moved from main Go repository, deleted Makefiles, ran gofix -r go1rename.

Tested with: go test code.google.com/p/go.crypto/...

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5564059

ssh/server_terminal.go

@@ -0,0 +1,81 @@
+// Copyright 2011 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 ssh
+
+// A Terminal is capable of parsing and generating virtual terminal
+// data from an SSH client.
+type Terminal interface {
+	ReadLine() (line string, err error)
+	SetSize(x, y int)
+	Write([]byte) (int, error)
+}
+
+// ServerTerminal contains the state for running a terminal that is capable of
+// reading lines of input.
+type ServerTerminal struct {
+	Term    Terminal
+	Channel Channel
+}
+
+// parsePtyRequest parses the payload of the pty-req message and extracts the
+// dimensions of the terminal. See RFC 4254, section 6.2.
+func parsePtyRequest(s []byte) (width, height int, ok bool) {
+	_, s, ok = parseString(s)
+	if !ok {
+		return
+	}
+	width32, s, ok := parseUint32(s)
+	if !ok {
+		return
+	}
+	height32, _, ok := parseUint32(s)
+	width = int(width32)
+	height = int(height32)
+	if width < 1 {
+		ok = false
+	}
+	if height < 1 {
+		ok = false
+	}
+	return
+}
+
+func (ss *ServerTerminal) Write(buf []byte) (n int, err error) {
+	return ss.Term.Write(buf)
+}
+
+// ReadLine returns a line of input from the terminal.
+func (ss *ServerTerminal) ReadLine() (line string, err error) {
+	for {
+		if line, err = ss.Term.ReadLine(); err == nil {
+			return
+		}
+
+		req, ok := err.(ChannelRequest)
+		if !ok {
+			return
+		}
+
+		ok = false
+		switch req.Request {
+		case "pty-req":
+			var width, height int
+			width, height, ok = parsePtyRequest(req.Payload)
+			ss.Term.SetSize(width, height)
+		case "shell":
+			ok = true
+			if len(req.Payload) > 0 {
+				// We don't accept any commands, only the default shell.
+				ok = false
+			}
+		case "env":
+			ok = true
+		}
+		if req.WantReply {
+			ss.Channel.AckRequest(ok)
+		}
+	}
+	panic("unreachable")
+}