go.crypto/ssh: cosmetic: move remaining channel code into channel.go

This CL scratches an itch by moving the remaining channel related code
into channel.go.

R=agl
CC=golang-dev
https://golang.org/cl/6454126

ssh/channel.go

diff --git a/ssh/channel.go b/ssh/channel.go
index 53a2d8c..9ca6789 100644
--- a/ssh/channel.go
+++ b/ssh/channel.go
@@ -408,3 +408,121 @@
 func (c *serverChan) ExtraData() []byte {
 	return c.extraData
 }
+
+// A clientChan represents a single RFC 4254 channel multiplexed 
+// over a SSH connection.
+type clientChan struct {
+	channel
+	stdin  *chanWriter
+	stdout *chanReader
+	stderr *chanReader
+	msg    chan interface{}
+}
+
+// newClientChan returns a partially constructed *clientChan
+// using the local id provided. To be usable clientChan.remoteId
+// needs to be assigned once known.
+func newClientChan(cc conn, id uint32) *clientChan {
+	c := &clientChan{
+		channel: channel{
+			conn:      cc,
+			localId:   id,
+			remoteWin: window{Cond: newCond()},
+		},
+		msg: make(chan interface{}, 16),
+	}
+	c.stdin = &chanWriter{
+		channel: &c.channel,
+	}
+	c.stdout = &chanReader{
+		channel: &c.channel,
+		buffer:  newBuffer(),
+	}
+	c.stderr = &chanReader{
+		channel: &c.channel,
+		buffer:  newBuffer(),
+	}
+	return c
+}
+
+// waitForChannelOpenResponse, if successful, fills out
+// the remoteId and records any initial window advertisement.
+func (c *clientChan) waitForChannelOpenResponse() error {
+	switch msg := (<-c.msg).(type) {
+	case *channelOpenConfirmMsg:
+		// fixup remoteId field
+		c.remoteId = msg.MyId
+		// TODO(dfc) asset this is < 2^31.
+		c.maxPacketSize = msg.MaxPacketSize
+		c.remoteWin.add(msg.MyWindow)
+		return nil
+	case *channelOpenFailureMsg:
+		return errors.New(safeString(msg.Message))
+	}
+	return errors.New("ssh: unexpected packet")
+}
+
+// Close closes the channel. This does not close the underlying connection.
+func (c *clientChan) Close() error {
+	if !c.weClosed {
+		c.weClosed = true
+		return c.sendClose()
+	}
+	return nil
+}
+
+// A chanWriter represents the stdin of a remote process.
+type chanWriter struct {
+	*channel
+}
+
+// Write writes data to the remote process's standard input.
+func (w *chanWriter) Write(data []byte) (written int, err error) {
+	for len(data) > 0 {
+		// never send more data than maxPacketSize even if
+		// there is sufficent window.
+		n := min(int(w.maxPacketSize), len(data))
+		n = int(w.remoteWin.reserve(uint32(n)))
+		remoteId := w.remoteId
+		packet := []byte{
+			msgChannelData,
+			byte(remoteId >> 24), byte(remoteId >> 16), byte(remoteId >> 8), byte(remoteId),
+			byte(n >> 24), byte(n >> 16), byte(n >> 8), byte(n),
+		}
+		if err = w.writePacket(append(packet, data[:n]...)); err != nil {
+			break
+		}
+		data = data[n:]
+		written += n
+	}
+	return
+}
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+func (w *chanWriter) Close() error {
+	return w.sendEOF()
+}
+
+// A chanReader represents stdout or stderr of a remote process.
+type chanReader struct {
+	*channel // the channel backing this reader
+	*buffer
+}
+
+// Read reads data from the remote process's stdout or stderr.
+func (r *chanReader) Read(buf []byte) (int, error) {
+	n, err := r.buffer.Read(buf)
+	if err != nil {
+		if err == io.EOF {
+			return n, err
+		}
+		return 0, err
+	}
+	return n, r.sendWindowAdj(n)
+}

ssh/client.go

diff --git a/ssh/client.go b/ssh/client.go
index b266f0d..ddb291f 100644
--- a/ssh/client.go
+++ b/ssh/client.go
@@ -456,68 +456,6 @@
 	return c.Rand
 }
 
-// A clientChan represents a single RFC 4254 channel that is multiplexed
-// over a single SSH connection.
-type clientChan struct {
-	channel
-	stdin  *chanWriter
-	stdout *chanReader
-	stderr *chanReader
-	msg    chan interface{}
-}
-
-// newClientChan returns a partially constructed *clientChan
-// using the local id provided. To be usable clientChan.remoteId
-// needs to be assigned once known.
-func newClientChan(cc conn, id uint32) *clientChan {
-	c := &clientChan{
-		channel: channel{
-			conn:      cc,
-			localId:   id,
-			remoteWin: window{Cond: newCond()},
-		},
-		msg: make(chan interface{}, 16),
-	}
-	c.stdin = &chanWriter{
-		channel: &c.channel,
-	}
-	c.stdout = &chanReader{
-		channel: &c.channel,
-		buffer:  newBuffer(),
-	}
-	c.stderr = &chanReader{
-		channel: &c.channel,
-		buffer:  newBuffer(),
-	}
-	return c
-}
-
-// waitForChannelOpenResponse, if successful, fills out
-// the remoteId and records any initial window advertisement.
-func (c *clientChan) waitForChannelOpenResponse() error {
-	switch msg := (<-c.msg).(type) {
-	case *channelOpenConfirmMsg:
-		// fixup remoteId field
-		c.remoteId = msg.MyId
-		// TODO(dfc) asset this is < 2^31.
-		c.maxPacketSize = msg.MaxPacketSize
-		c.remoteWin.add(msg.MyWindow)
-		return nil
-	case *channelOpenFailureMsg:
-		return errors.New(safeString(msg.Message))
-	}
-	return errors.New("ssh: unexpected packet")
-}
-
-// Close closes the channel. This does not close the underlying connection.
-func (c *clientChan) Close() error {
-	if !c.weClosed {
-		c.weClosed = true
-		return c.sendClose()
-	}
-	return nil
-}
-
 // Thread safe channel list.
 type chanList struct {
 	// protects concurrent access to chans
@@ -575,59 +513,3 @@
 		close(ch.msg)
 	}
 }
-
-// A chanWriter represents the stdin of a remote process.
-type chanWriter struct {
-	*channel
-}
-
-// Write writes data to the remote process's standard input.
-func (w *chanWriter) Write(data []byte) (written int, err error) {
-	for len(data) > 0 {
-		// never send more data than maxPacketSize even if
-		// there is sufficent window.
-		n := min(int(w.maxPacketSize), len(data))
-		n = int(w.remoteWin.reserve(uint32(n)))
-		remoteId := w.remoteId
-		packet := []byte{
-			msgChannelData,
-			byte(remoteId >> 24), byte(remoteId >> 16), byte(remoteId >> 8), byte(remoteId),
-			byte(n >> 24), byte(n >> 16), byte(n >> 8), byte(n),
-		}
-		if err = w.writePacket(append(packet, data[:n]...)); err != nil {
-			break
-		}
-		data = data[n:]
-		written += n
-	}
-	return
-}
-
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}
-
-func (w *chanWriter) Close() error {
-	return w.sendEOF()
-}
-
-// A chanReader represents stdout or stderr of a remote process.
-type chanReader struct {
-	*channel // the channel backing this reader
-	*buffer
-}
-
-// Read reads data from the remote process's stdout or stderr.
-func (r *chanReader) Read(buf []byte) (int, error) {
-	n, err := r.buffer.Read(buf)
-	if err != nil {
-		if err == io.EOF {
-			return n, err
-		}
-		return 0, err
-	}
-	return n, r.sendWindowAdj(n)
-}