mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-12-05 10:02:47 +00:00
0e56867d8b
Bumps [golang.org/x/crypto](https://github.com/golang/crypto) from 0.16.0 to 0.17.0. - [Commits](https://github.com/golang/crypto/compare/v0.16.0...v0.17.0) --- updated-dependencies: - dependency-name: golang.org/x/crypto dependency-type: direct:production ... Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
646 lines
16 KiB
Go
646 lines
16 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package ssh
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import (
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"encoding/binary"
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"errors"
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"fmt"
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"io"
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"log"
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"sync"
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)
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const (
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minPacketLength = 9
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// channelMaxPacket contains the maximum number of bytes that will be
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// sent in a single packet. As per RFC 4253, section 6.1, 32k is also
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// the minimum.
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channelMaxPacket = 1 << 15
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// We follow OpenSSH here.
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channelWindowSize = 64 * channelMaxPacket
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)
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// NewChannel represents an incoming request to a channel. It must either be
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// accepted for use by calling Accept, or rejected by calling Reject.
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type NewChannel interface {
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// Accept accepts the channel creation request. It returns the Channel
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// and a Go channel containing SSH requests. The Go channel must be
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// serviced otherwise the Channel will hang.
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Accept() (Channel, <-chan *Request, error)
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// Reject rejects the channel creation request. After calling
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// this, no other methods on the Channel may be called.
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Reject(reason RejectionReason, message string) error
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// ChannelType returns the type of the channel, as supplied by the
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// client.
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ChannelType() string
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// ExtraData returns the arbitrary payload for this channel, as supplied
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// by the client. This data is specific to the channel type.
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ExtraData() []byte
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}
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// A Channel is an ordered, reliable, flow-controlled, duplex stream
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// that is multiplexed over an SSH connection.
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type Channel interface {
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// Read reads up to len(data) bytes from the channel.
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Read(data []byte) (int, error)
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// Write writes len(data) bytes to the channel.
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Write(data []byte) (int, error)
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// Close signals end of channel use. No data may be sent after this
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// call.
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Close() error
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// CloseWrite signals the end of sending in-band
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// data. Requests may still be sent, and the other side may
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// still send data
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CloseWrite() error
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// SendRequest sends a channel request. If wantReply is true,
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// it will wait for a reply and return the result as a
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// boolean, otherwise the return value will be false. Channel
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// requests are out-of-band messages so they may be sent even
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// if the data stream is closed or blocked by flow control.
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// If the channel is closed before a reply is returned, io.EOF
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// is returned.
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SendRequest(name string, wantReply bool, payload []byte) (bool, error)
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// Stderr returns an io.ReadWriter that writes to this channel
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// with the extended data type set to stderr. Stderr may
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// safely be read and written from a different goroutine than
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// Read and Write respectively.
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Stderr() io.ReadWriter
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}
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// Request is a request sent outside of the normal stream of
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// data. Requests can either be specific to an SSH channel, or they
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// can be global.
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type Request struct {
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Type string
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WantReply bool
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Payload []byte
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ch *channel
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mux *mux
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}
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// Reply sends a response to a request. It must be called for all requests
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// where WantReply is true and is a no-op otherwise. The payload argument is
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// ignored for replies to channel-specific requests.
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func (r *Request) Reply(ok bool, payload []byte) error {
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if !r.WantReply {
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return nil
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}
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if r.ch == nil {
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return r.mux.ackRequest(ok, payload)
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}
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return r.ch.ackRequest(ok)
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}
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// RejectionReason is an enumeration used when rejecting channel creation
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// requests. See RFC 4254, section 5.1.
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type RejectionReason uint32
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const (
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Prohibited RejectionReason = iota + 1
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ConnectionFailed
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UnknownChannelType
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ResourceShortage
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)
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// String converts the rejection reason to human readable form.
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func (r RejectionReason) String() string {
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switch r {
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case Prohibited:
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return "administratively prohibited"
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case ConnectionFailed:
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return "connect failed"
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case UnknownChannelType:
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return "unknown channel type"
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case ResourceShortage:
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return "resource shortage"
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}
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return fmt.Sprintf("unknown reason %d", int(r))
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}
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func min(a uint32, b int) uint32 {
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if a < uint32(b) {
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return a
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}
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return uint32(b)
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}
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type channelDirection uint8
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const (
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channelInbound channelDirection = iota
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channelOutbound
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)
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// channel is an implementation of the Channel interface that works
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// with the mux class.
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type channel struct {
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// R/O after creation
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chanType string
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extraData []byte
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localId, remoteId uint32
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// maxIncomingPayload and maxRemotePayload are the maximum
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// payload sizes of normal and extended data packets for
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// receiving and sending, respectively. The wire packet will
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// be 9 or 13 bytes larger (excluding encryption overhead).
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maxIncomingPayload uint32
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maxRemotePayload uint32
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mux *mux
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// decided is set to true if an accept or reject message has been sent
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// (for outbound channels) or received (for inbound channels).
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decided bool
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// direction contains either channelOutbound, for channels created
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// locally, or channelInbound, for channels created by the peer.
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direction channelDirection
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// Pending internal channel messages.
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msg chan interface{}
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// Since requests have no ID, there can be only one request
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// with WantReply=true outstanding. This lock is held by a
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// goroutine that has such an outgoing request pending.
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sentRequestMu sync.Mutex
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incomingRequests chan *Request
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sentEOF bool
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// thread-safe data
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remoteWin window
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pending *buffer
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extPending *buffer
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// windowMu protects myWindow, the flow-control window, and myConsumed,
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// the number of bytes consumed since we last increased myWindow
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windowMu sync.Mutex
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myWindow uint32
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myConsumed uint32
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// writeMu serializes calls to mux.conn.writePacket() and
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// protects sentClose and packetPool. This mutex must be
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// different from windowMu, as writePacket can block if there
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// is a key exchange pending.
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writeMu sync.Mutex
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sentClose bool
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// packetPool has a buffer for each extended channel ID to
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// save allocations during writes.
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packetPool map[uint32][]byte
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}
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// writePacket sends a packet. If the packet is a channel close, it updates
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// sentClose. This method takes the lock c.writeMu.
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func (ch *channel) writePacket(packet []byte) error {
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ch.writeMu.Lock()
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if ch.sentClose {
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ch.writeMu.Unlock()
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return io.EOF
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}
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ch.sentClose = (packet[0] == msgChannelClose)
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err := ch.mux.conn.writePacket(packet)
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ch.writeMu.Unlock()
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return err
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}
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func (ch *channel) sendMessage(msg interface{}) error {
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if debugMux {
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log.Printf("send(%d): %#v", ch.mux.chanList.offset, msg)
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}
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p := Marshal(msg)
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binary.BigEndian.PutUint32(p[1:], ch.remoteId)
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return ch.writePacket(p)
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}
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// WriteExtended writes data to a specific extended stream. These streams are
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// used, for example, for stderr.
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func (ch *channel) WriteExtended(data []byte, extendedCode uint32) (n int, err error) {
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if ch.sentEOF {
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return 0, io.EOF
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}
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// 1 byte message type, 4 bytes remoteId, 4 bytes data length
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opCode := byte(msgChannelData)
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headerLength := uint32(9)
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if extendedCode > 0 {
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headerLength += 4
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opCode = msgChannelExtendedData
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}
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ch.writeMu.Lock()
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packet := ch.packetPool[extendedCode]
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// We don't remove the buffer from packetPool, so
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// WriteExtended calls from different goroutines will be
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// flagged as errors by the race detector.
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ch.writeMu.Unlock()
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for len(data) > 0 {
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space := min(ch.maxRemotePayload, len(data))
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if space, err = ch.remoteWin.reserve(space); err != nil {
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return n, err
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}
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if want := headerLength + space; uint32(cap(packet)) < want {
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packet = make([]byte, want)
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} else {
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packet = packet[:want]
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}
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todo := data[:space]
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packet[0] = opCode
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binary.BigEndian.PutUint32(packet[1:], ch.remoteId)
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if extendedCode > 0 {
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binary.BigEndian.PutUint32(packet[5:], uint32(extendedCode))
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}
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binary.BigEndian.PutUint32(packet[headerLength-4:], uint32(len(todo)))
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copy(packet[headerLength:], todo)
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if err = ch.writePacket(packet); err != nil {
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return n, err
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}
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n += len(todo)
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data = data[len(todo):]
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}
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ch.writeMu.Lock()
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ch.packetPool[extendedCode] = packet
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ch.writeMu.Unlock()
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return n, err
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}
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func (ch *channel) handleData(packet []byte) error {
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headerLen := 9
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isExtendedData := packet[0] == msgChannelExtendedData
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if isExtendedData {
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headerLen = 13
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}
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if len(packet) < headerLen {
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// malformed data packet
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return parseError(packet[0])
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}
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var extended uint32
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if isExtendedData {
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extended = binary.BigEndian.Uint32(packet[5:])
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}
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length := binary.BigEndian.Uint32(packet[headerLen-4 : headerLen])
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if length == 0 {
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return nil
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}
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if length > ch.maxIncomingPayload {
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// TODO(hanwen): should send Disconnect?
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return errors.New("ssh: incoming packet exceeds maximum payload size")
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}
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data := packet[headerLen:]
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if length != uint32(len(data)) {
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return errors.New("ssh: wrong packet length")
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}
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ch.windowMu.Lock()
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if ch.myWindow < length {
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ch.windowMu.Unlock()
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// TODO(hanwen): should send Disconnect with reason?
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return errors.New("ssh: remote side wrote too much")
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}
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ch.myWindow -= length
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ch.windowMu.Unlock()
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if extended == 1 {
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ch.extPending.write(data)
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} else if extended > 0 {
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// discard other extended data.
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} else {
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ch.pending.write(data)
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}
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return nil
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}
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func (c *channel) adjustWindow(adj uint32) error {
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c.windowMu.Lock()
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// Since myConsumed and myWindow are managed on our side, and can never
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// exceed the initial window setting, we don't worry about overflow.
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c.myConsumed += adj
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var sendAdj uint32
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if (channelWindowSize-c.myWindow > 3*c.maxIncomingPayload) ||
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(c.myWindow < channelWindowSize/2) {
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sendAdj = c.myConsumed
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c.myConsumed = 0
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c.myWindow += sendAdj
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}
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c.windowMu.Unlock()
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if sendAdj == 0 {
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return nil
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}
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return c.sendMessage(windowAdjustMsg{
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AdditionalBytes: sendAdj,
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})
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}
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func (c *channel) ReadExtended(data []byte, extended uint32) (n int, err error) {
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switch extended {
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case 1:
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n, err = c.extPending.Read(data)
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case 0:
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n, err = c.pending.Read(data)
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default:
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return 0, fmt.Errorf("ssh: extended code %d unimplemented", extended)
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}
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if n > 0 {
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err = c.adjustWindow(uint32(n))
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// sendWindowAdjust can return io.EOF if the remote
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// peer has closed the connection, however we want to
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// defer forwarding io.EOF to the caller of Read until
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// the buffer has been drained.
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if n > 0 && err == io.EOF {
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err = nil
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}
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}
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return n, err
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}
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func (c *channel) close() {
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c.pending.eof()
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c.extPending.eof()
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close(c.msg)
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close(c.incomingRequests)
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c.writeMu.Lock()
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// This is not necessary for a normal channel teardown, but if
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// there was another error, it is.
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c.sentClose = true
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c.writeMu.Unlock()
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// Unblock writers.
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c.remoteWin.close()
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}
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// responseMessageReceived is called when a success or failure message is
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// received on a channel to check that such a message is reasonable for the
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// given channel.
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func (ch *channel) responseMessageReceived() error {
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if ch.direction == channelInbound {
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return errors.New("ssh: channel response message received on inbound channel")
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}
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if ch.decided {
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return errors.New("ssh: duplicate response received for channel")
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}
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ch.decided = true
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return nil
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}
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func (ch *channel) handlePacket(packet []byte) error {
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switch packet[0] {
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case msgChannelData, msgChannelExtendedData:
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return ch.handleData(packet)
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case msgChannelClose:
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ch.sendMessage(channelCloseMsg{PeersID: ch.remoteId})
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ch.mux.chanList.remove(ch.localId)
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ch.close()
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return nil
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case msgChannelEOF:
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// RFC 4254 is mute on how EOF affects dataExt messages but
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// it is logical to signal EOF at the same time.
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ch.extPending.eof()
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ch.pending.eof()
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return nil
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}
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decoded, err := decode(packet)
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if err != nil {
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return err
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}
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switch msg := decoded.(type) {
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case *channelOpenFailureMsg:
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if err := ch.responseMessageReceived(); err != nil {
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return err
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}
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ch.mux.chanList.remove(msg.PeersID)
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ch.msg <- msg
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case *channelOpenConfirmMsg:
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if err := ch.responseMessageReceived(); err != nil {
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return err
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}
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if msg.MaxPacketSize < minPacketLength || msg.MaxPacketSize > 1<<31 {
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return fmt.Errorf("ssh: invalid MaxPacketSize %d from peer", msg.MaxPacketSize)
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}
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ch.remoteId = msg.MyID
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ch.maxRemotePayload = msg.MaxPacketSize
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ch.remoteWin.add(msg.MyWindow)
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ch.msg <- msg
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case *windowAdjustMsg:
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if !ch.remoteWin.add(msg.AdditionalBytes) {
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return fmt.Errorf("ssh: invalid window update for %d bytes", msg.AdditionalBytes)
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}
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case *channelRequestMsg:
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req := Request{
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Type: msg.Request,
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WantReply: msg.WantReply,
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Payload: msg.RequestSpecificData,
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ch: ch,
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}
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ch.incomingRequests <- &req
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default:
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ch.msg <- msg
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}
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return nil
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}
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func (m *mux) newChannel(chanType string, direction channelDirection, extraData []byte) *channel {
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ch := &channel{
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remoteWin: window{Cond: newCond()},
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myWindow: channelWindowSize,
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pending: newBuffer(),
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extPending: newBuffer(),
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direction: direction,
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incomingRequests: make(chan *Request, chanSize),
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msg: make(chan interface{}, chanSize),
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chanType: chanType,
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extraData: extraData,
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mux: m,
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packetPool: make(map[uint32][]byte),
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}
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ch.localId = m.chanList.add(ch)
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return ch
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}
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var errUndecided = errors.New("ssh: must Accept or Reject channel")
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var errDecidedAlready = errors.New("ssh: can call Accept or Reject only once")
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|
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type extChannel struct {
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code uint32
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ch *channel
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}
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func (e *extChannel) Write(data []byte) (n int, err error) {
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return e.ch.WriteExtended(data, e.code)
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}
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func (e *extChannel) Read(data []byte) (n int, err error) {
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return e.ch.ReadExtended(data, e.code)
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}
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func (ch *channel) Accept() (Channel, <-chan *Request, error) {
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if ch.decided {
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return nil, nil, errDecidedAlready
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}
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ch.maxIncomingPayload = channelMaxPacket
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confirm := channelOpenConfirmMsg{
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PeersID: ch.remoteId,
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MyID: ch.localId,
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MyWindow: ch.myWindow,
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MaxPacketSize: ch.maxIncomingPayload,
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}
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ch.decided = true
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if err := ch.sendMessage(confirm); err != nil {
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return nil, nil, err
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}
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return ch, ch.incomingRequests, nil
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}
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func (ch *channel) Reject(reason RejectionReason, message string) error {
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if ch.decided {
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return errDecidedAlready
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}
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reject := channelOpenFailureMsg{
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PeersID: ch.remoteId,
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Reason: reason,
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Message: message,
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Language: "en",
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}
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ch.decided = true
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return ch.sendMessage(reject)
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}
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func (ch *channel) Read(data []byte) (int, error) {
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if !ch.decided {
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return 0, errUndecided
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}
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return ch.ReadExtended(data, 0)
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}
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func (ch *channel) Write(data []byte) (int, error) {
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if !ch.decided {
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return 0, errUndecided
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}
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return ch.WriteExtended(data, 0)
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}
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func (ch *channel) CloseWrite() error {
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if !ch.decided {
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return errUndecided
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}
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|
ch.sentEOF = true
|
|
return ch.sendMessage(channelEOFMsg{
|
|
PeersID: ch.remoteId})
|
|
}
|
|
|
|
func (ch *channel) Close() error {
|
|
if !ch.decided {
|
|
return errUndecided
|
|
}
|
|
|
|
return ch.sendMessage(channelCloseMsg{
|
|
PeersID: ch.remoteId})
|
|
}
|
|
|
|
// Extended returns an io.ReadWriter that sends and receives data on the given,
|
|
// SSH extended stream. Such streams are used, for example, for stderr.
|
|
func (ch *channel) Extended(code uint32) io.ReadWriter {
|
|
if !ch.decided {
|
|
return nil
|
|
}
|
|
return &extChannel{code, ch}
|
|
}
|
|
|
|
func (ch *channel) Stderr() io.ReadWriter {
|
|
return ch.Extended(1)
|
|
}
|
|
|
|
func (ch *channel) SendRequest(name string, wantReply bool, payload []byte) (bool, error) {
|
|
if !ch.decided {
|
|
return false, errUndecided
|
|
}
|
|
|
|
if wantReply {
|
|
ch.sentRequestMu.Lock()
|
|
defer ch.sentRequestMu.Unlock()
|
|
}
|
|
|
|
msg := channelRequestMsg{
|
|
PeersID: ch.remoteId,
|
|
Request: name,
|
|
WantReply: wantReply,
|
|
RequestSpecificData: payload,
|
|
}
|
|
|
|
if err := ch.sendMessage(msg); err != nil {
|
|
return false, err
|
|
}
|
|
|
|
if wantReply {
|
|
m, ok := (<-ch.msg)
|
|
if !ok {
|
|
return false, io.EOF
|
|
}
|
|
switch m.(type) {
|
|
case *channelRequestFailureMsg:
|
|
return false, nil
|
|
case *channelRequestSuccessMsg:
|
|
return true, nil
|
|
default:
|
|
return false, fmt.Errorf("ssh: unexpected response to channel request: %#v", m)
|
|
}
|
|
}
|
|
|
|
return false, nil
|
|
}
|
|
|
|
// ackRequest either sends an ack or nack to the channel request.
|
|
func (ch *channel) ackRequest(ok bool) error {
|
|
if !ch.decided {
|
|
return errUndecided
|
|
}
|
|
|
|
var msg interface{}
|
|
if !ok {
|
|
msg = channelRequestFailureMsg{
|
|
PeersID: ch.remoteId,
|
|
}
|
|
} else {
|
|
msg = channelRequestSuccessMsg{
|
|
PeersID: ch.remoteId,
|
|
}
|
|
}
|
|
return ch.sendMessage(msg)
|
|
}
|
|
|
|
func (ch *channel) ChannelType() string {
|
|
return ch.chanType
|
|
}
|
|
|
|
func (ch *channel) ExtraData() []byte {
|
|
return ch.extraData
|
|
}
|