Vendor packages and add Makefile

* Vendors packages
  * Adds a Makefile that uses docker to build a static binary against musl
using alpine linux.

Signed-off-by: Gabriel Adrian Samfira <gsamfira@cloudbasesolutions.com>

vendor/github.com/pkg/sftp/internal/encoding/ssh/filexfer/attrs.go

@@ -0,0 +1,326 @@
+package filexfer
+
+// Attributes related flags.
+const (
+	AttrSize        = 1 << iota // SSH_FILEXFER_ATTR_SIZE
+	AttrUIDGID                  // SSH_FILEXFER_ATTR_UIDGID
+	AttrPermissions             // SSH_FILEXFER_ATTR_PERMISSIONS
+	AttrACModTime               // SSH_FILEXFER_ACMODTIME
+
+	AttrExtended = 1 << 31 // SSH_FILEXFER_ATTR_EXTENDED
+)
+
+// Attributes defines the file attributes type defined in draft-ietf-secsh-filexfer-02
+//
+// Defined in: https://tools.ietf.org/html/draft-ietf-secsh-filexfer-02#section-5
+type Attributes struct {
+	Flags uint32
+
+	// AttrSize
+	Size uint64
+
+	// AttrUIDGID
+	UID uint32
+	GID uint32
+
+	// AttrPermissions
+	Permissions FileMode
+
+	// AttrACmodTime
+	ATime uint32
+	MTime uint32
+
+	// AttrExtended
+	ExtendedAttributes []ExtendedAttribute
+}
+
+// GetSize returns the Size field and a bool that is true if and only if the value is valid/defined.
+func (a *Attributes) GetSize() (size uint64, ok bool) {
+	return a.Size, a.Flags&AttrSize != 0
+}
+
+// SetSize is a convenience function that sets the Size field,
+// and marks the field as valid/defined in Flags.
+func (a *Attributes) SetSize(size uint64) {
+	a.Flags |= AttrSize
+	a.Size = size
+}
+
+// GetUIDGID returns the UID and GID fields and a bool that is true if and only if the values are valid/defined.
+func (a *Attributes) GetUIDGID() (uid, gid uint32, ok bool) {
+	return a.UID, a.GID, a.Flags&AttrUIDGID != 0
+}
+
+// SetUIDGID is a convenience function that sets the UID and GID fields,
+// and marks the fields as valid/defined in Flags.
+func (a *Attributes) SetUIDGID(uid, gid uint32) {
+	a.Flags |= AttrUIDGID
+	a.UID = uid
+	a.GID = gid
+}
+
+// GetPermissions returns the Permissions field and a bool that is true if and only if the value is valid/defined.
+func (a *Attributes) GetPermissions() (perms FileMode, ok bool) {
+	return a.Permissions, a.Flags&AttrPermissions != 0
+}
+
+// SetPermissions is a convenience function that sets the Permissions field,
+// and marks the field as valid/defined in Flags.
+func (a *Attributes) SetPermissions(perms FileMode) {
+	a.Flags |= AttrPermissions
+	a.Permissions = perms
+}
+
+// GetACModTime returns the ATime and MTime fields and a bool that is true if and only if the values are valid/defined.
+func (a *Attributes) GetACModTime() (atime, mtime uint32, ok bool) {
+	return a.ATime, a.MTime, a.Flags&AttrACModTime != 0
+	return a.ATime, a.MTime, a.Flags&AttrACModTime != 0
+}
+
+// SetACModTime is a convenience function that sets the ATime and MTime fields,
+// and marks the fields as valid/defined in Flags.
+func (a *Attributes) SetACModTime(atime, mtime uint32) {
+	a.Flags |= AttrACModTime
+	a.ATime = atime
+	a.MTime = mtime
+}
+
+// Len returns the number of bytes a would marshal into.
+func (a *Attributes) Len() int {
+	length := 4
+
+	if a.Flags&AttrSize != 0 {
+		length += 8
+	}
+
+	if a.Flags&AttrUIDGID != 0 {
+		length += 4 + 4
+	}
+
+	if a.Flags&AttrPermissions != 0 {
+		length += 4
+	}
+
+	if a.Flags&AttrACModTime != 0 {
+		length += 4 + 4
+	}
+
+	if a.Flags&AttrExtended != 0 {
+		length += 4
+
+		for _, ext := range a.ExtendedAttributes {
+			length += ext.Len()
+		}
+	}
+
+	return length
+}
+
+// MarshalInto marshals e onto the end of the given Buffer.
+func (a *Attributes) MarshalInto(b *Buffer) {
+	b.AppendUint32(a.Flags)
+
+	if a.Flags&AttrSize != 0 {
+		b.AppendUint64(a.Size)
+	}
+
+	if a.Flags&AttrUIDGID != 0 {
+		b.AppendUint32(a.UID)
+		b.AppendUint32(a.GID)
+	}
+
+	if a.Flags&AttrPermissions != 0 {
+		b.AppendUint32(uint32(a.Permissions))
+	}
+
+	if a.Flags&AttrACModTime != 0 {
+		b.AppendUint32(a.ATime)
+		b.AppendUint32(a.MTime)
+	}
+
+	if a.Flags&AttrExtended != 0 {
+		b.AppendUint32(uint32(len(a.ExtendedAttributes)))
+
+		for _, ext := range a.ExtendedAttributes {
+			ext.MarshalInto(b)
+		}
+	}
+}
+
+// MarshalBinary returns a as the binary encoding of a.
+func (a *Attributes) MarshalBinary() ([]byte, error) {
+	buf := NewBuffer(make([]byte, 0, a.Len()))
+	a.MarshalInto(buf)
+	return buf.Bytes(), nil
+}
+
+// UnmarshalFrom unmarshals an Attributes from the given Buffer into e.
+//
+// NOTE: The values of fields not covered in the a.Flags are explicitly undefined.
+func (a *Attributes) UnmarshalFrom(b *Buffer) (err error) {
+	flags, err := b.ConsumeUint32()
+	if err != nil {
+		return err
+	}
+
+	return a.XXX_UnmarshalByFlags(flags, b)
+}
+
+// XXX_UnmarshalByFlags uses the pre-existing a.Flags field to determine which fields to decode.
+// DO NOT USE THIS: it is an anti-corruption function to implement existing internal usage in pkg/sftp.
+// This function is not a part of any compatibility promise.
+func (a *Attributes) XXX_UnmarshalByFlags(flags uint32, b *Buffer) (err error) {
+	a.Flags = flags
+
+	// Short-circuit dummy attributes.
+	if a.Flags == 0 {
+		return nil
+	}
+
+	if a.Flags&AttrSize != 0 {
+		if a.Size, err = b.ConsumeUint64(); err != nil {
+			return err
+		}
+	}
+
+	if a.Flags&AttrUIDGID != 0 {
+		if a.UID, err = b.ConsumeUint32(); err != nil {
+			return err
+		}
+
+		if a.GID, err = b.ConsumeUint32(); err != nil {
+			return err
+		}
+	}
+
+	if a.Flags&AttrPermissions != 0 {
+		m, err := b.ConsumeUint32()
+		if err != nil {
+			return err
+		}
+
+		a.Permissions = FileMode(m)
+	}
+
+	if a.Flags&AttrACModTime != 0 {
+		if a.ATime, err = b.ConsumeUint32(); err != nil {
+			return err
+		}
+
+		if a.MTime, err = b.ConsumeUint32(); err != nil {
+			return err
+		}
+	}
+
+	if a.Flags&AttrExtended != 0 {
+		count, err := b.ConsumeUint32()
+		if err != nil {
+			return err
+		}
+
+		a.ExtendedAttributes = make([]ExtendedAttribute, count)
+		for i := range a.ExtendedAttributes {
+			a.ExtendedAttributes[i].UnmarshalFrom(b)
+		}
+	}
+
+	return nil
+}
+
+// UnmarshalBinary decodes the binary encoding of Attributes into e.
+func (a *Attributes) UnmarshalBinary(data []byte) error {
+	return a.UnmarshalFrom(NewBuffer(data))
+}
+
+// ExtendedAttribute defines the extended file attribute type defined in draft-ietf-secsh-filexfer-02
+//
+// Defined in: https://tools.ietf.org/html/draft-ietf-secsh-filexfer-02#section-5
+type ExtendedAttribute struct {
+	Type string
+	Data string
+}
+
+// Len returns the number of bytes e would marshal into.
+func (e *ExtendedAttribute) Len() int {
+	return 4 + len(e.Type) + 4 + len(e.Data)
+}
+
+// MarshalInto marshals e onto the end of the given Buffer.
+func (e *ExtendedAttribute) MarshalInto(b *Buffer) {
+	b.AppendString(e.Type)
+	b.AppendString(e.Data)
+}
+
+// MarshalBinary returns e as the binary encoding of e.
+func (e *ExtendedAttribute) MarshalBinary() ([]byte, error) {
+	buf := NewBuffer(make([]byte, 0, e.Len()))
+	e.MarshalInto(buf)
+	return buf.Bytes(), nil
+}
+
+// UnmarshalFrom unmarshals an ExtendedAattribute from the given Buffer into e.
+func (e *ExtendedAttribute) UnmarshalFrom(b *Buffer) (err error) {
+	if e.Type, err = b.ConsumeString(); err != nil {
+		return err
+	}
+
+	if e.Data, err = b.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// UnmarshalBinary decodes the binary encoding of ExtendedAttribute into e.
+func (e *ExtendedAttribute) UnmarshalBinary(data []byte) error {
+	return e.UnmarshalFrom(NewBuffer(data))
+}
+
+// NameEntry implements the SSH_FXP_NAME repeated data type from draft-ietf-secsh-filexfer-02
+//
+// This type is incompatible with versions 4 or higher.
+type NameEntry struct {
+	Filename string
+	Longname string
+	Attrs    Attributes
+}
+
+// Len returns the number of bytes e would marshal into.
+func (e *NameEntry) Len() int {
+	return 4 + len(e.Filename) + 4 + len(e.Longname) + e.Attrs.Len()
+}
+
+// MarshalInto marshals e onto the end of the given Buffer.
+func (e *NameEntry) MarshalInto(b *Buffer) {
+	b.AppendString(e.Filename)
+	b.AppendString(e.Longname)
+
+	e.Attrs.MarshalInto(b)
+}
+
+// MarshalBinary returns e as the binary encoding of e.
+func (e *NameEntry) MarshalBinary() ([]byte, error) {
+	buf := NewBuffer(make([]byte, 0, e.Len()))
+	e.MarshalInto(buf)
+	return buf.Bytes(), nil
+}
+
+// UnmarshalFrom unmarshals an NameEntry from the given Buffer into e.
+//
+// NOTE: The values of fields not covered in the a.Flags are explicitly undefined.
+func (e *NameEntry) UnmarshalFrom(b *Buffer) (err error) {
+	if e.Filename, err = b.ConsumeString(); err != nil {
+		return err
+	}
+
+	if e.Longname, err = b.ConsumeString(); err != nil {
+		return err
+	}
+
+	return e.Attrs.UnmarshalFrom(b)
+}
+
+// UnmarshalBinary decodes the binary encoding of NameEntry into e.
+func (e *NameEntry) UnmarshalBinary(data []byte) error {
+	return e.UnmarshalFrom(NewBuffer(data))
+}

vendor/github.com/pkg/sftp/internal/encoding/ssh/filexfer/buffer.go

@@ -0,0 +1,293 @@
+package filexfer
+
+import (
+	"encoding/binary"
+	"errors"
+)
+
+// Various encoding errors.
+var (
+	ErrShortPacket = errors.New("packet too short")
+	ErrLongPacket  = errors.New("packet too long")
+)
+
+// Buffer wraps up the various encoding details of the SSH format.
+//
+// Data types are encoded as per section 4 from https://tools.ietf.org/html/draft-ietf-secsh-architecture-09#page-8
+type Buffer struct {
+	b   []byte
+	off int
+}
+
+// NewBuffer creates and initializes a new buffer using buf as its initial contents.
+// The new buffer takes ownership of buf, and the caller should not use buf after this call.
+//
+// In most cases, new(Buffer) (or just declaring a Buffer variable) is sufficient to initialize a Buffer.
+func NewBuffer(buf []byte) *Buffer {
+	return &Buffer{
+		b: buf,
+	}
+}
+
+// NewMarshalBuffer creates a new Buffer ready to start marshaling a Packet into.
+// It preallocates enough space for uint32(length), uint8(type), uint32(request-id) and size more bytes.
+func NewMarshalBuffer(size int) *Buffer {
+	return NewBuffer(make([]byte, 4+1+4+size))
+}
+
+// Bytes returns a slice of length b.Len() holding the unconsumed bytes in the Buffer.
+// The slice is valid for use only until the next buffer modification
+// (that is, only until the next call to an Append or Consume method).
+func (b *Buffer) Bytes() []byte {
+	return b.b[b.off:]
+}
+
+// Len returns the number of unconsumed bytes in the buffer.
+func (b *Buffer) Len() int { return len(b.b) - b.off }
+
+// Cap returns the capacity of the buffer’s underlying byte slice,
+// that is, the total space allocated for the buffer’s data.
+func (b *Buffer) Cap() int { return cap(b.b) }
+
+// Reset resets the buffer to be empty, but it retains the underlying storage for use by future Appends.
+func (b *Buffer) Reset() {
+	b.b = b.b[:0]
+	b.off = 0
+}
+
+// StartPacket resets and initializes the buffer to be ready to start marshaling a packet into.
+// It truncates the buffer, reserves space for uint32(length), then appends the given packetType and requestID.
+func (b *Buffer) StartPacket(packetType PacketType, requestID uint32) {
+	b.b, b.off = append(b.b[:0], make([]byte, 4)...), 0
+
+	b.AppendUint8(uint8(packetType))
+	b.AppendUint32(requestID)
+}
+
+// Packet finalizes the packet started from StartPacket.
+// It is expected that this will end the ownership of the underlying byte-slice,
+// and so the returned byte-slices may be reused the same as any other byte-slice,
+// the caller should not use this buffer after this call.
+//
+// It writes the packet body length into the first four bytes of the buffer in network byte order (big endian).
+// The packet body length is the length of this buffer less the 4-byte length itself, plus the length of payload.
+//
+// It is assumed that no Consume methods have been called on this buffer,
+// and so it returns the whole underlying slice.
+func (b *Buffer) Packet(payload []byte) (header, payloadPassThru []byte, err error) {
+	b.PutLength(len(b.b) - 4 + len(payload))
+
+	return b.b, payload, nil
+}
+
+// ConsumeUint8 consumes a single byte from the buffer.
+// If the buffer does not have enough data, it will return ErrShortPacket.
+func (b *Buffer) ConsumeUint8() (uint8, error) {
+	if b.Len() < 1 {
+		return 0, ErrShortPacket
+	}
+
+	var v uint8
+	v, b.off = b.b[b.off], b.off+1
+	return v, nil
+}
+
+// AppendUint8 appends a single byte into the buffer.
+func (b *Buffer) AppendUint8(v uint8) {
+	b.b = append(b.b, v)
+}
+
+// ConsumeBool consumes a single byte from the buffer, and returns true if that byte is non-zero.
+// If the buffer does not have enough data, it will return ErrShortPacket.
+func (b *Buffer) ConsumeBool() (bool, error) {
+	v, err := b.ConsumeUint8()
+	if err != nil {
+		return false, err
+	}
+
+	return v != 0, nil
+}
+
+// AppendBool appends a single bool into the buffer.
+// It encodes it as a single byte, with false as 0, and true as 1.
+func (b *Buffer) AppendBool(v bool) {
+	if v {
+		b.AppendUint8(1)
+	} else {
+		b.AppendUint8(0)
+	}
+}
+
+// ConsumeUint16 consumes a single uint16 from the buffer, in network byte order (big-endian).
+// If the buffer does not have enough data, it will return ErrShortPacket.
+func (b *Buffer) ConsumeUint16() (uint16, error) {
+	if b.Len() < 2 {
+		return 0, ErrShortPacket
+	}
+
+	v := binary.BigEndian.Uint16(b.b[b.off:])
+	b.off += 2
+	return v, nil
+}
+
+// AppendUint16 appends single uint16 into the buffer, in network byte order (big-endian).
+func (b *Buffer) AppendUint16(v uint16) {
+	b.b = append(b.b,
+		byte(v>>8),
+		byte(v>>0),
+	)
+}
+
+// unmarshalUint32 is used internally to read the packet length.
+// It is unsafe, and so not exported.
+// Even within this package, its use should be avoided.
+func unmarshalUint32(b []byte) uint32 {
+	return binary.BigEndian.Uint32(b[:4])
+}
+
+// ConsumeUint32 consumes a single uint32 from the buffer, in network byte order (big-endian).
+// If the buffer does not have enough data, it will return ErrShortPacket.
+func (b *Buffer) ConsumeUint32() (uint32, error) {
+	if b.Len() < 4 {
+		return 0, ErrShortPacket
+	}
+
+	v := binary.BigEndian.Uint32(b.b[b.off:])
+	b.off += 4
+	return v, nil
+}
+
+// AppendUint32 appends a single uint32 into the buffer, in network byte order (big-endian).
+func (b *Buffer) AppendUint32(v uint32) {
+	b.b = append(b.b,
+		byte(v>>24),
+		byte(v>>16),
+		byte(v>>8),
+		byte(v>>0),
+	)
+}
+
+// ConsumeUint64 consumes a single uint64 from the buffer, in network byte order (big-endian).
+// If the buffer does not have enough data, it will return ErrShortPacket.
+func (b *Buffer) ConsumeUint64() (uint64, error) {
+	if b.Len() < 8 {
+		return 0, ErrShortPacket
+	}
+
+	v := binary.BigEndian.Uint64(b.b[b.off:])
+	b.off += 8
+	return v, nil
+}
+
+// AppendUint64 appends a single uint64 into the buffer, in network byte order (big-endian).
+func (b *Buffer) AppendUint64(v uint64) {
+	b.b = append(b.b,
+		byte(v>>56),
+		byte(v>>48),
+		byte(v>>40),
+		byte(v>>32),
+		byte(v>>24),
+		byte(v>>16),
+		byte(v>>8),
+		byte(v>>0),
+	)
+}
+
+// ConsumeInt64 consumes a single int64 from the buffer, in network byte order (big-endian) with two’s complement.
+// If the buffer does not have enough data, it will return ErrShortPacket.
+func (b *Buffer) ConsumeInt64() (int64, error) {
+	u, err := b.ConsumeUint64()
+	if err != nil {
+		return 0, err
+	}
+
+	return int64(u), err
+}
+
+// AppendInt64 appends a single int64 into the buffer, in network byte order (big-endian) with two’s complement.
+func (b *Buffer) AppendInt64(v int64) {
+	b.AppendUint64(uint64(v))
+}
+
+// ConsumeByteSlice consumes a single string of raw binary data from the buffer.
+// A string is a uint32 length, followed by that number of raw bytes.
+// If the buffer does not have enough data, or defines a length larger than available, it will return ErrShortPacket.
+//
+// The returned slice aliases the buffer contents, and is valid only as long as the buffer is not reused
+// (that is, only until the next call to Reset, PutLength, StartPacket, or UnmarshalBinary).
+//
+// In no case will any Consume calls return overlapping slice aliases,
+// and Append calls are guaranteed to not disturb this slice alias.
+func (b *Buffer) ConsumeByteSlice() ([]byte, error) {
+	length, err := b.ConsumeUint32()
+	if err != nil {
+		return nil, err
+	}
+
+	if b.Len() < int(length) {
+		return nil, ErrShortPacket
+	}
+
+	v := b.b[b.off:]
+	if len(v) > int(length) {
+		v = v[:length:length]
+	}
+	b.off += int(length)
+	return v, nil
+}
+
+// AppendByteSlice appends a single string of raw binary data into the buffer.
+// A string is a uint32 length, followed by that number of raw bytes.
+func (b *Buffer) AppendByteSlice(v []byte) {
+	b.AppendUint32(uint32(len(v)))
+	b.b = append(b.b, v...)
+}
+
+// ConsumeString consumes a single string of binary data from the buffer.
+// A string is a uint32 length, followed by that number of raw bytes.
+// If the buffer does not have enough data, or defines a length larger than available, it will return ErrShortPacket.
+//
+// NOTE: Go implicitly assumes that strings contain UTF-8 encoded data.
+// All caveats on using arbitrary binary data in Go strings applies.
+func (b *Buffer) ConsumeString() (string, error) {
+	v, err := b.ConsumeByteSlice()
+	if err != nil {
+		return "", err
+	}
+
+	return string(v), nil
+}
+
+// AppendString appends a single string of binary data into the buffer.
+// A string is a uint32 length, followed by that number of raw bytes.
+func (b *Buffer) AppendString(v string) {
+	b.AppendByteSlice([]byte(v))
+}
+
+// PutLength writes the given size into the first four bytes of the buffer in network byte order (big endian).
+func (b *Buffer) PutLength(size int) {
+	if len(b.b) < 4 {
+		b.b = append(b.b, make([]byte, 4-len(b.b))...)
+	}
+
+	binary.BigEndian.PutUint32(b.b, uint32(size))
+}
+
+// MarshalBinary returns a clone of the full internal buffer.
+func (b *Buffer) MarshalBinary() ([]byte, error) {
+	clone := make([]byte, len(b.b))
+	n := copy(clone, b.b)
+	return clone[:n], nil
+}
+
+// UnmarshalBinary sets the internal buffer of b to be a clone of data, and zeros the internal offset.
+func (b *Buffer) UnmarshalBinary(data []byte) error {
+	if grow := len(data) - len(b.b); grow > 0 {
+		b.b = append(b.b, make([]byte, grow)...)
+	}
+
+	n := copy(b.b, data)
+	b.b = b.b[:n]
+	b.off = 0
+	return nil
+}

vendor/github.com/pkg/sftp/internal/encoding/ssh/filexfer/extended_packets.go

@@ -0,0 +1,142 @@
+package filexfer
+
+import (
+	"encoding"
+	"sync"
+)
+
+// ExtendedData aliases the untyped interface composition of encoding.BinaryMarshaler and encoding.BinaryUnmarshaler.
+type ExtendedData = interface {
+	encoding.BinaryMarshaler
+	encoding.BinaryUnmarshaler
+}
+
+// ExtendedDataConstructor defines a function that returns a new(ArbitraryExtendedPacket).
+type ExtendedDataConstructor func() ExtendedData
+
+var extendedPacketTypes = struct {
+	mu           sync.RWMutex
+	constructors map[string]ExtendedDataConstructor
+}{
+	constructors: make(map[string]ExtendedDataConstructor),
+}
+
+// RegisterExtendedPacketType defines a specific ExtendedDataConstructor for the given extension string.
+func RegisterExtendedPacketType(extension string, constructor ExtendedDataConstructor) {
+	extendedPacketTypes.mu.Lock()
+	defer extendedPacketTypes.mu.Unlock()
+
+	if _, exist := extendedPacketTypes.constructors[extension]; exist {
+		panic("encoding/ssh/filexfer: multiple registration of extended packet type " + extension)
+	}
+
+	extendedPacketTypes.constructors[extension] = constructor
+}
+
+func newExtendedPacket(extension string) ExtendedData {
+	extendedPacketTypes.mu.RLock()
+	defer extendedPacketTypes.mu.RUnlock()
+
+	if f := extendedPacketTypes.constructors[extension]; f != nil {
+		return f()
+	}
+
+	return new(Buffer)
+}
+
+// ExtendedPacket defines the SSH_FXP_CLOSE packet.
+type ExtendedPacket struct {
+	ExtendedRequest string
+
+	Data ExtendedData
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *ExtendedPacket) Type() PacketType {
+	return PacketTypeExtended
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+//
+// The Data is marshaled into binary, and returned as the payload.
+func (p *ExtendedPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 + len(p.ExtendedRequest) // string(extended-request)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeExtended, reqid)
+	buf.AppendString(p.ExtendedRequest)
+
+	if p.Data != nil {
+		payload, err = p.Data.MarshalBinary()
+		if err != nil {
+			return nil, nil, err
+		}
+	}
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+//
+// If p.Data is nil, and the extension has been registered, a new type will be made from the registration.
+// If the extension has not been registered, then a new Buffer will be allocated.
+// Then the request-specific-data will be unmarshaled from the rest of the buffer.
+func (p *ExtendedPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.ExtendedRequest, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	if p.Data == nil {
+		p.Data = newExtendedPacket(p.ExtendedRequest)
+	}
+
+	return p.Data.UnmarshalBinary(buf.Bytes())
+}
+
+// ExtendedReplyPacket defines the SSH_FXP_CLOSE packet.
+type ExtendedReplyPacket struct {
+	Data ExtendedData
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *ExtendedReplyPacket) Type() PacketType {
+	return PacketTypeExtendedReply
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+//
+// The Data is marshaled into binary, and returned as the payload.
+func (p *ExtendedReplyPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		buf = NewMarshalBuffer(0)
+	}
+
+	buf.StartPacket(PacketTypeExtendedReply, reqid)
+
+	if p.Data != nil {
+		payload, err = p.Data.MarshalBinary()
+		if err != nil {
+			return nil, nil, err
+		}
+	}
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+//
+// If p.Data is nil, and there is request-specific-data,
+// then the request-specific-data will be wrapped in a Buffer and assigned to p.Data.
+func (p *ExtendedReplyPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Data == nil {
+		p.Data = new(Buffer)
+	}
+
+	return p.Data.UnmarshalBinary(buf.Bytes())
+}

vendor/github.com/pkg/sftp/internal/encoding/ssh/filexfer/extensions.go

@@ -0,0 +1,46 @@
+package filexfer
+
+// ExtensionPair defines the extension-pair type defined in draft-ietf-secsh-filexfer-13.
+// This type is backwards-compatible with how draft-ietf-secsh-filexfer-02 defines extensions.
+//
+// Defined in: https://tools.ietf.org/html/draft-ietf-secsh-filexfer-13#section-4.2
+type ExtensionPair struct {
+	Name string
+	Data string
+}
+
+// Len returns the number of bytes e would marshal into.
+func (e *ExtensionPair) Len() int {
+	return 4 + len(e.Name) + 4 + len(e.Data)
+}
+
+// MarshalInto marshals e onto the end of the given Buffer.
+func (e *ExtensionPair) MarshalInto(buf *Buffer) {
+	buf.AppendString(e.Name)
+	buf.AppendString(e.Data)
+}
+
+// MarshalBinary returns e as the binary encoding of e.
+func (e *ExtensionPair) MarshalBinary() ([]byte, error) {
+	buf := NewBuffer(make([]byte, 0, e.Len()))
+	e.MarshalInto(buf)
+	return buf.Bytes(), nil
+}
+
+// UnmarshalFrom unmarshals an ExtensionPair from the given Buffer into e.
+func (e *ExtensionPair) UnmarshalFrom(buf *Buffer) (err error) {
+	if e.Name, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	if e.Data, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// UnmarshalBinary decodes the binary encoding of ExtensionPair into e.
+func (e *ExtensionPair) UnmarshalBinary(data []byte) error {
+	return e.UnmarshalFrom(NewBuffer(data))
+}

vendor/github.com/pkg/sftp/internal/encoding/ssh/filexfer/filexfer.go

@@ -0,0 +1,54 @@
+// Package filexfer implements the wire encoding for secsh-filexfer as described in https://tools.ietf.org/html/draft-ietf-secsh-filexfer-02
+package filexfer
+
+// PacketMarshaller narrowly defines packets that will only be transmitted.
+//
+// ExtendedPacket types will often only implement this interface,
+// since decoding the whole packet body of an ExtendedPacket can only be done dependent on the ExtendedRequest field.
+type PacketMarshaller interface {
+	// MarshalPacket is the primary intended way to encode a packet.
+	// The request-id for the packet is set from reqid.
+	//
+	// An optional buffer may be given in b.
+	// If the buffer has a minimum capacity, it shall be truncated and used to marshal the header into.
+	// The minimum capacity for the packet must be a constant expression, and should be at least 9.
+	//
+	// It shall return the main body of the encoded packet in header,
+	// and may optionally return an additional payload to be written immediately after the header.
+	//
+	// It shall encode in the first 4-bytes of the header the proper length of the rest of the header+payload.
+	MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error)
+}
+
+// Packet defines the behavior of a full generic SFTP packet.
+//
+// InitPacket, and VersionPacket are not generic SFTP packets, and instead implement (Un)MarshalBinary.
+//
+// ExtendedPacket types should not iplement this interface,
+// since decoding the whole packet body of an ExtendedPacket can only be done dependent on the ExtendedRequest field.
+type Packet interface {
+	PacketMarshaller
+
+	// Type returns the SSH_FXP_xy value associated with the specific packet.
+	Type() PacketType
+
+	// UnmarshalPacketBody decodes a packet body from the given Buffer.
+	// It is assumed that the common header values of the length, type and request-id have already been consumed.
+	//
+	// Implementations should not alias the given Buffer,
+	// instead they can consider prepopulating an internal buffer as a hint,
+	// and copying into that buffer if it has sufficient length.
+	UnmarshalPacketBody(buf *Buffer) error
+}
+
+// ComposePacket converts returns from MarshalPacket into an equivalent call to MarshalBinary.
+func ComposePacket(header, payload []byte, err error) ([]byte, error) {
+	return append(header, payload...), err
+}
+
+// Default length values,
+// Defined in draft-ietf-secsh-filexfer-02 section 3.
+const (
+	DefaultMaxPacketLength = 34000
+	DefaultMaxDataLength   = 32768
+)

vendor/github.com/pkg/sftp/internal/encoding/ssh/filexfer/fx.go

@@ -0,0 +1,147 @@
+package filexfer
+
+import (
+	"fmt"
+)
+
+// Status defines the SFTP error codes used in SSH_FXP_STATUS response packets.
+type Status uint32
+
+// Defines the various SSH_FX_* values.
+const (
+	// see draft-ietf-secsh-filexfer-02
+	// https://tools.ietf.org/html/draft-ietf-secsh-filexfer-02#section-7
+	StatusOK = Status(iota)
+	StatusEOF
+	StatusNoSuchFile
+	StatusPermissionDenied
+	StatusFailure
+	StatusBadMessage
+	StatusNoConnection
+	StatusConnectionLost
+	StatusOPUnsupported
+
+	// https://tools.ietf.org/html/draft-ietf-secsh-filexfer-03#section-7
+	StatusV4InvalidHandle
+	StatusV4NoSuchPath
+	StatusV4FileAlreadyExists
+	StatusV4WriteProtect
+
+	// https://tools.ietf.org/html/draft-ietf-secsh-filexfer-04#section-7
+	StatusV4NoMedia
+
+	// https://tools.ietf.org/html/draft-ietf-secsh-filexfer-05#section-7
+	StatusV5NoSpaceOnFilesystem
+	StatusV5QuotaExceeded
+	StatusV5UnknownPrincipal
+	StatusV5LockConflict
+
+	// https://tools.ietf.org/html/draft-ietf-secsh-filexfer-06#section-8
+	StatusV6DirNotEmpty
+	StatusV6NotADirectory
+	StatusV6InvalidFilename
+	StatusV6LinkLoop
+
+	// https://tools.ietf.org/html/draft-ietf-secsh-filexfer-07#section-8
+	StatusV6CannotDelete
+	StatusV6InvalidParameter
+	StatusV6FileIsADirectory
+	StatusV6ByteRangeLockConflict
+	StatusV6ByteRangeLockRefused
+	StatusV6DeletePending
+
+	// https://tools.ietf.org/html/draft-ietf-secsh-filexfer-08#section-8.1
+	StatusV6FileCorrupt
+
+	// https://tools.ietf.org/html/draft-ietf-secsh-filexfer-10#section-9.1
+	StatusV6OwnerInvalid
+	StatusV6GroupInvalid
+
+	// https://tools.ietf.org/html/draft-ietf-secsh-filexfer-13#section-9.1
+	StatusV6NoMatchingByteRangeLock
+)
+
+func (s Status) Error() string {
+	return s.String()
+}
+
+// Is returns true if the target is the same Status code,
+// or target is a StatusPacket with the same Status code.
+func (s Status) Is(target error) bool {
+	if target, ok := target.(*StatusPacket); ok {
+		return target.StatusCode == s
+	}
+
+	return s == target
+}
+
+func (s Status) String() string {
+	switch s {
+	case StatusOK:
+		return "SSH_FX_OK"
+	case StatusEOF:
+		return "SSH_FX_EOF"
+	case StatusNoSuchFile:
+		return "SSH_FX_NO_SUCH_FILE"
+	case StatusPermissionDenied:
+		return "SSH_FX_PERMISSION_DENIED"
+	case StatusFailure:
+		return "SSH_FX_FAILURE"
+	case StatusBadMessage:
+		return "SSH_FX_BAD_MESSAGE"
+	case StatusNoConnection:
+		return "SSH_FX_NO_CONNECTION"
+	case StatusConnectionLost:
+		return "SSH_FX_CONNECTION_LOST"
+	case StatusOPUnsupported:
+		return "SSH_FX_OP_UNSUPPORTED"
+	case StatusV4InvalidHandle:
+		return "SSH_FX_INVALID_HANDLE"
+	case StatusV4NoSuchPath:
+		return "SSH_FX_NO_SUCH_PATH"
+	case StatusV4FileAlreadyExists:
+		return "SSH_FX_FILE_ALREADY_EXISTS"
+	case StatusV4WriteProtect:
+		return "SSH_FX_WRITE_PROTECT"
+	case StatusV4NoMedia:
+		return "SSH_FX_NO_MEDIA"
+	case StatusV5NoSpaceOnFilesystem:
+		return "SSH_FX_NO_SPACE_ON_FILESYSTEM"
+	case StatusV5QuotaExceeded:
+		return "SSH_FX_QUOTA_EXCEEDED"
+	case StatusV5UnknownPrincipal:
+		return "SSH_FX_UNKNOWN_PRINCIPAL"
+	case StatusV5LockConflict:
+		return "SSH_FX_LOCK_CONFLICT"
+	case StatusV6DirNotEmpty:
+		return "SSH_FX_DIR_NOT_EMPTY"
+	case StatusV6NotADirectory:
+		return "SSH_FX_NOT_A_DIRECTORY"
+	case StatusV6InvalidFilename:
+		return "SSH_FX_INVALID_FILENAME"
+	case StatusV6LinkLoop:
+		return "SSH_FX_LINK_LOOP"
+	case StatusV6CannotDelete:
+		return "SSH_FX_CANNOT_DELETE"
+	case StatusV6InvalidParameter:
+		return "SSH_FX_INVALID_PARAMETER"
+	case StatusV6FileIsADirectory:
+		return "SSH_FX_FILE_IS_A_DIRECTORY"
+	case StatusV6ByteRangeLockConflict:
+		return "SSH_FX_BYTE_RANGE_LOCK_CONFLICT"
+	case StatusV6ByteRangeLockRefused:
+		return "SSH_FX_BYTE_RANGE_LOCK_REFUSED"
+	case StatusV6DeletePending:
+		return "SSH_FX_DELETE_PENDING"
+	case StatusV6FileCorrupt:
+		return "SSH_FX_FILE_CORRUPT"
+	case StatusV6OwnerInvalid:
+		return "SSH_FX_OWNER_INVALID"
+	case StatusV6GroupInvalid:
+		return "SSH_FX_GROUP_INVALID"
+	case StatusV6NoMatchingByteRangeLock:
+		return "SSH_FX_NO_MATCHING_BYTE_RANGE_LOCK"
+	default:
+		return fmt.Sprintf("SSH_FX_UNKNOWN(%d)", s)
+	}
+}

vendor/github.com/pkg/sftp/internal/encoding/ssh/filexfer/fxp.go

@@ -0,0 +1,124 @@
+package filexfer
+
+import (
+	"fmt"
+)
+
+// PacketType defines the various SFTP packet types.
+type PacketType uint8
+
+// Request packet types.
+const (
+	// https://tools.ietf.org/html/draft-ietf-secsh-filexfer-02#section-3
+	PacketTypeInit = PacketType(iota + 1)
+	PacketTypeVersion
+	PacketTypeOpen
+	PacketTypeClose
+	PacketTypeRead
+	PacketTypeWrite
+	PacketTypeLStat
+	PacketTypeFStat
+	PacketTypeSetstat
+	PacketTypeFSetstat
+	PacketTypeOpenDir
+	PacketTypeReadDir
+	PacketTypeRemove
+	PacketTypeMkdir
+	PacketTypeRmdir
+	PacketTypeRealPath
+	PacketTypeStat
+	PacketTypeRename
+	PacketTypeReadLink
+	PacketTypeSymlink
+
+	// https://tools.ietf.org/html/draft-ietf-secsh-filexfer-07#section-3.3
+	PacketTypeV6Link
+
+	// https://tools.ietf.org/html/draft-ietf-secsh-filexfer-08#section-3.3
+	PacketTypeV6Block
+	PacketTypeV6Unblock
+)
+
+// Response packet types.
+const (
+	// https://tools.ietf.org/html/draft-ietf-secsh-filexfer-02#section-3
+	PacketTypeStatus = PacketType(iota + 101)
+	PacketTypeHandle
+	PacketTypeData
+	PacketTypeName
+	PacketTypeAttrs
+)
+
+// Extended packet types.
+const (
+	// https://tools.ietf.org/html/draft-ietf-secsh-filexfer-02#section-3
+	PacketTypeExtended = PacketType(iota + 200)
+	PacketTypeExtendedReply
+)
+
+func (f PacketType) String() string {
+	switch f {
+	case PacketTypeInit:
+		return "SSH_FXP_INIT"
+	case PacketTypeVersion:
+		return "SSH_FXP_VERSION"
+	case PacketTypeOpen:
+		return "SSH_FXP_OPEN"
+	case PacketTypeClose:
+		return "SSH_FXP_CLOSE"
+	case PacketTypeRead:
+		return "SSH_FXP_READ"
+	case PacketTypeWrite:
+		return "SSH_FXP_WRITE"
+	case PacketTypeLStat:
+		return "SSH_FXP_LSTAT"
+	case PacketTypeFStat:
+		return "SSH_FXP_FSTAT"
+	case PacketTypeSetstat:
+		return "SSH_FXP_SETSTAT"
+	case PacketTypeFSetstat:
+		return "SSH_FXP_FSETSTAT"
+	case PacketTypeOpenDir:
+		return "SSH_FXP_OPENDIR"
+	case PacketTypeReadDir:
+		return "SSH_FXP_READDIR"
+	case PacketTypeRemove:
+		return "SSH_FXP_REMOVE"
+	case PacketTypeMkdir:
+		return "SSH_FXP_MKDIR"
+	case PacketTypeRmdir:
+		return "SSH_FXP_RMDIR"
+	case PacketTypeRealPath:
+		return "SSH_FXP_REALPATH"
+	case PacketTypeStat:
+		return "SSH_FXP_STAT"
+	case PacketTypeRename:
+		return "SSH_FXP_RENAME"
+	case PacketTypeReadLink:
+		return "SSH_FXP_READLINK"
+	case PacketTypeSymlink:
+		return "SSH_FXP_SYMLINK"
+	case PacketTypeV6Link:
+		return "SSH_FXP_LINK"
+	case PacketTypeV6Block:
+		return "SSH_FXP_BLOCK"
+	case PacketTypeV6Unblock:
+		return "SSH_FXP_UNBLOCK"
+	case PacketTypeStatus:
+		return "SSH_FXP_STATUS"
+	case PacketTypeHandle:
+		return "SSH_FXP_HANDLE"
+	case PacketTypeData:
+		return "SSH_FXP_DATA"
+	case PacketTypeName:
+		return "SSH_FXP_NAME"
+	case PacketTypeAttrs:
+		return "SSH_FXP_ATTRS"
+	case PacketTypeExtended:
+		return "SSH_FXP_EXTENDED"
+	case PacketTypeExtendedReply:
+		return "SSH_FXP_EXTENDED_REPLY"
+	default:
+		return fmt.Sprintf("SSH_FXP_UNKNOWN(%d)", f)
+	}
+}

vendor/github.com/pkg/sftp/internal/encoding/ssh/filexfer/handle_packets.go

@@ -0,0 +1,249 @@
+package filexfer
+
+// ClosePacket defines the SSH_FXP_CLOSE packet.
+type ClosePacket struct {
+	Handle string
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *ClosePacket) Type() PacketType {
+	return PacketTypeClose
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *ClosePacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 + len(p.Handle) // string(handle)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeClose, reqid)
+	buf.AppendString(p.Handle)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *ClosePacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Handle, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// ReadPacket defines the SSH_FXP_READ packet.
+type ReadPacket struct {
+	Handle string
+	Offset uint64
+	Len    uint32
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *ReadPacket) Type() PacketType {
+	return PacketTypeRead
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *ReadPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		// string(handle) + uint64(offset) + uint32(len)
+		size := 4 + len(p.Handle) + 8 + 4
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeRead, reqid)
+	buf.AppendString(p.Handle)
+	buf.AppendUint64(p.Offset)
+	buf.AppendUint32(p.Len)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *ReadPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Handle, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	if p.Offset, err = buf.ConsumeUint64(); err != nil {
+		return err
+	}
+
+	if p.Len, err = buf.ConsumeUint32(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// WritePacket defines the SSH_FXP_WRITE packet.
+type WritePacket struct {
+	Handle string
+	Offset uint64
+	Data   []byte
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *WritePacket) Type() PacketType {
+	return PacketTypeWrite
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *WritePacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		// string(handle) + uint64(offset) + uint32(len(data)); data content in payload
+		size := 4 + len(p.Handle) + 8 + 4
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeWrite, reqid)
+	buf.AppendString(p.Handle)
+	buf.AppendUint64(p.Offset)
+	buf.AppendUint32(uint32(len(p.Data)))
+
+	return buf.Packet(p.Data)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+//
+// If p.Data is already populated, and of sufficient length to hold the data,
+// then this will copy the data into that byte slice.
+//
+// If p.Data has a length insufficient to hold the data,
+// then this will make a new slice of sufficient length, and copy the data into that.
+//
+// This means this _does not_ alias any of the data buffer that is passed in.
+func (p *WritePacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Handle, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	if p.Offset, err = buf.ConsumeUint64(); err != nil {
+		return err
+	}
+
+	data, err := buf.ConsumeByteSlice()
+	if err != nil {
+		return err
+	}
+
+	if len(p.Data) < len(data) {
+		p.Data = make([]byte, len(data))
+	}
+
+	n := copy(p.Data, data)
+	p.Data = p.Data[:n]
+	return nil
+}
+
+// FStatPacket defines the SSH_FXP_FSTAT packet.
+type FStatPacket struct {
+	Handle string
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *FStatPacket) Type() PacketType {
+	return PacketTypeFStat
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *FStatPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 + len(p.Handle) // string(handle)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeFStat, reqid)
+	buf.AppendString(p.Handle)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *FStatPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Handle, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// FSetstatPacket defines the SSH_FXP_FSETSTAT packet.
+type FSetstatPacket struct {
+	Handle string
+	Attrs  Attributes
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *FSetstatPacket) Type() PacketType {
+	return PacketTypeFSetstat
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *FSetstatPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 + len(p.Handle) + p.Attrs.Len() // string(handle) + ATTRS(attrs)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeFSetstat, reqid)
+	buf.AppendString(p.Handle)
+
+	p.Attrs.MarshalInto(buf)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *FSetstatPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Handle, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return p.Attrs.UnmarshalFrom(buf)
+}
+
+// ReadDirPacket defines the SSH_FXP_READDIR packet.
+type ReadDirPacket struct {
+	Handle string
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *ReadDirPacket) Type() PacketType {
+	return PacketTypeReadDir
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *ReadDirPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 + len(p.Handle) // string(handle)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeReadDir, reqid)
+	buf.AppendString(p.Handle)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *ReadDirPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Handle, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}

vendor/github.com/pkg/sftp/internal/encoding/ssh/filexfer/init_packets.go

@@ -0,0 +1,99 @@
+package filexfer
+
+// InitPacket defines the SSH_FXP_INIT packet.
+type InitPacket struct {
+	Version    uint32
+	Extensions []*ExtensionPair
+}
+
+// MarshalBinary returns p as the binary encoding of p.
+func (p *InitPacket) MarshalBinary() ([]byte, error) {
+	size := 1 + 4 // byte(type) + uint32(version)
+
+	for _, ext := range p.Extensions {
+		size += ext.Len()
+	}
+
+	b := NewBuffer(make([]byte, 4, 4+size))
+	b.AppendUint8(uint8(PacketTypeInit))
+	b.AppendUint32(p.Version)
+
+	for _, ext := range p.Extensions {
+		ext.MarshalInto(b)
+	}
+
+	b.PutLength(size)
+
+	return b.Bytes(), nil
+}
+
+// UnmarshalBinary unmarshals a full raw packet out of the given data.
+// It is assumed that the uint32(length) has already been consumed to receive the data.
+// It is also assumed that the uint8(type) has already been consumed to which packet to unmarshal into.
+func (p *InitPacket) UnmarshalBinary(data []byte) (err error) {
+	buf := NewBuffer(data)
+
+	if p.Version, err = buf.ConsumeUint32(); err != nil {
+		return err
+	}
+
+	for buf.Len() > 0 {
+		var ext ExtensionPair
+		if err := ext.UnmarshalFrom(buf); err != nil {
+			return err
+		}
+
+		p.Extensions = append(p.Extensions, &ext)
+	}
+
+	return nil
+}
+
+// VersionPacket defines the SSH_FXP_VERSION packet.
+type VersionPacket struct {
+	Version    uint32
+	Extensions []*ExtensionPair
+}
+
+// MarshalBinary returns p as the binary encoding of p.
+func (p *VersionPacket) MarshalBinary() ([]byte, error) {
+	size := 1 + 4 // byte(type) + uint32(version)
+
+	for _, ext := range p.Extensions {
+		size += ext.Len()
+	}
+
+	b := NewBuffer(make([]byte, 4, 4+size))
+	b.AppendUint8(uint8(PacketTypeVersion))
+	b.AppendUint32(p.Version)
+
+	for _, ext := range p.Extensions {
+		ext.MarshalInto(b)
+	}
+
+	b.PutLength(size)
+
+	return b.Bytes(), nil
+}
+
+// UnmarshalBinary unmarshals a full raw packet out of the given data.
+// It is assumed that the uint32(length) has already been consumed to receive the data.
+// It is also assumed that the uint8(type) has already been consumed to which packet to unmarshal into.
+func (p *VersionPacket) UnmarshalBinary(data []byte) (err error) {
+	buf := NewBuffer(data)
+
+	if p.Version, err = buf.ConsumeUint32(); err != nil {
+		return err
+	}
+
+	for buf.Len() > 0 {
+		var ext ExtensionPair
+		if err := ext.UnmarshalFrom(buf); err != nil {
+			return err
+		}
+
+		p.Extensions = append(p.Extensions, &ext)
+	}
+
+	return nil
+}

vendor/github.com/pkg/sftp/internal/encoding/ssh/filexfer/open_packets.go

@@ -0,0 +1,89 @@
+package filexfer
+
+// SSH_FXF_* flags.
+const (
+	FlagRead      = 1 << iota // SSH_FXF_READ
+	FlagWrite                 // SSH_FXF_WRITE
+	FlagAppend                // SSH_FXF_APPEND
+	FlagCreate                // SSH_FXF_CREAT
+	FlagTruncate              // SSH_FXF_TRUNC
+	FlagExclusive             // SSH_FXF_EXCL
+)
+
+// OpenPacket defines the SSH_FXP_OPEN packet.
+type OpenPacket struct {
+	Filename string
+	PFlags   uint32
+	Attrs    Attributes
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *OpenPacket) Type() PacketType {
+	return PacketTypeOpen
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *OpenPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		// string(filename) + uint32(pflags) + ATTRS(attrs)
+		size := 4 + len(p.Filename) + 4 + p.Attrs.Len()
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeOpen, reqid)
+	buf.AppendString(p.Filename)
+	buf.AppendUint32(p.PFlags)
+
+	p.Attrs.MarshalInto(buf)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *OpenPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Filename, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	if p.PFlags, err = buf.ConsumeUint32(); err != nil {
+		return err
+	}
+
+	return p.Attrs.UnmarshalFrom(buf)
+}
+
+// OpenDirPacket defines the SSH_FXP_OPENDIR packet.
+type OpenDirPacket struct {
+	Path string
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *OpenDirPacket) Type() PacketType {
+	return PacketTypeOpenDir
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *OpenDirPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 + len(p.Path) // string(path)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeOpenDir, reqid)
+	buf.AppendString(p.Path)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *OpenDirPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Path, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}

vendor/github.com/pkg/sftp/internal/encoding/ssh/filexfer/packets.go

@@ -0,0 +1,323 @@
+package filexfer
+
+import (
+	"errors"
+	"fmt"
+	"io"
+)
+
+// smallBufferSize is an initial allocation minimal capacity.
+const smallBufferSize = 64
+
+func newPacketFromType(typ PacketType) (Packet, error) {
+	switch typ {
+	case PacketTypeOpen:
+		return new(OpenPacket), nil
+	case PacketTypeClose:
+		return new(ClosePacket), nil
+	case PacketTypeRead:
+		return new(ReadPacket), nil
+	case PacketTypeWrite:
+		return new(WritePacket), nil
+	case PacketTypeLStat:
+		return new(LStatPacket), nil
+	case PacketTypeFStat:
+		return new(FStatPacket), nil
+	case PacketTypeSetstat:
+		return new(SetstatPacket), nil
+	case PacketTypeFSetstat:
+		return new(FSetstatPacket), nil
+	case PacketTypeOpenDir:
+		return new(OpenDirPacket), nil
+	case PacketTypeReadDir:
+		return new(ReadDirPacket), nil
+	case PacketTypeRemove:
+		return new(RemovePacket), nil
+	case PacketTypeMkdir:
+		return new(MkdirPacket), nil
+	case PacketTypeRmdir:
+		return new(RmdirPacket), nil
+	case PacketTypeRealPath:
+		return new(RealPathPacket), nil
+	case PacketTypeStat:
+		return new(StatPacket), nil
+	case PacketTypeRename:
+		return new(RenamePacket), nil
+	case PacketTypeReadLink:
+		return new(ReadLinkPacket), nil
+	case PacketTypeSymlink:
+		return new(SymlinkPacket), nil
+	case PacketTypeExtended:
+		return new(ExtendedPacket), nil
+	default:
+		return nil, fmt.Errorf("unexpected request packet type: %v", typ)
+	}
+}
+
+// RawPacket implements the general packet format from draft-ietf-secsh-filexfer-02
+//
+// RawPacket is intended for use in clients receiving responses,
+// where a response will be expected to be of a limited number of types,
+// and unmarshaling unknown/unexpected response packets is unnecessary.
+//
+// For servers expecting to receive arbitrary request packet types,
+// use RequestPacket.
+//
+// Defined in https://tools.ietf.org/html/draft-ietf-secsh-filexfer-02#section-3
+type RawPacket struct {
+	PacketType PacketType
+	RequestID  uint32
+
+	Data Buffer
+}
+
+// Type returns the Type field defining the SSH_FXP_xy type for this packet.
+func (p *RawPacket) Type() PacketType {
+	return p.PacketType
+}
+
+// Reset clears the pointers and reference-semantic variables of RawPacket,
+// releasing underlying resources, and making them and the RawPacket suitable to be reused,
+// so long as no other references have been kept.
+func (p *RawPacket) Reset() {
+	p.Data = Buffer{}
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+//
+// The internal p.RequestID is overridden by the reqid argument.
+func (p *RawPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		buf = NewMarshalBuffer(0)
+	}
+
+	buf.StartPacket(p.PacketType, reqid)
+
+	return buf.Packet(p.Data.Bytes())
+}
+
+// MarshalBinary returns p as the binary encoding of p.
+//
+// This is a convenience implementation primarily intended for tests,
+// because it is inefficient with allocations.
+func (p *RawPacket) MarshalBinary() ([]byte, error) {
+	return ComposePacket(p.MarshalPacket(p.RequestID, nil))
+}
+
+// UnmarshalFrom decodes a RawPacket from the given Buffer into p.
+//
+// The Data field will alias the passed in Buffer,
+// so the buffer passed in should not be reused before RawPacket.Reset().
+func (p *RawPacket) UnmarshalFrom(buf *Buffer) error {
+	typ, err := buf.ConsumeUint8()
+	if err != nil {
+		return err
+	}
+
+	p.PacketType = PacketType(typ)
+
+	if p.RequestID, err = buf.ConsumeUint32(); err != nil {
+		return err
+	}
+
+	p.Data = *buf
+	return nil
+}
+
+// UnmarshalBinary decodes a full raw packet out of the given data.
+// It is assumed that the uint32(length) has already been consumed to receive the data.
+//
+// This is a convenience implementation primarily intended for tests,
+// because this must clone the given data byte slice,
+// as Data is not allowed to alias any part of the data byte slice.
+func (p *RawPacket) UnmarshalBinary(data []byte) error {
+	clone := make([]byte, len(data))
+	n := copy(clone, data)
+	return p.UnmarshalFrom(NewBuffer(clone[:n]))
+}
+
+// readPacket reads a uint32 length-prefixed binary data packet from r.
+// using the given byte slice as a backing array.
+//
+// If the packet length read from r is bigger than maxPacketLength,
+// or greater than math.MaxInt32 on a 32-bit implementation,
+// then a `ErrLongPacket` error will be returned.
+//
+// If the given byte slice is insufficient to hold the packet,
+// then it will be extended to fill the packet size.
+func readPacket(r io.Reader, b []byte, maxPacketLength uint32) ([]byte, error) {
+	if cap(b) < 4 {
+		// We will need allocate our own buffer just for reading the packet length.
+
+		// However, we don’t really want to allocate an extremely narrow buffer (4-bytes),
+		// and cause unnecessary allocation churn from both length reads and small packet reads,
+		// so we use smallBufferSize from the bytes package as a reasonable guess.
+
+		// But if callers really do want to force narrow throw-away allocation of every packet body,
+		// they can do so with a buffer of capacity 4.
+		b = make([]byte, smallBufferSize)
+	}
+
+	if _, err := io.ReadFull(r, b[:4]); err != nil {
+		return nil, err
+	}
+
+	length := unmarshalUint32(b)
+	if int(length) < 5 {
+		// Must have at least uint8(type) and uint32(request-id)
+
+		if int(length) < 0 {
+			// Only possible when strconv.IntSize == 32,
+			// the packet length is longer than math.MaxInt32,
+			// and thus longer than any possible slice.
+			return nil, ErrLongPacket
+		}
+
+		return nil, ErrShortPacket
+	}
+	if length > maxPacketLength {
+		return nil, ErrLongPacket
+	}
+
+	if int(length) > cap(b) {
+		// We know int(length) must be positive, because of tests above.
+		b = make([]byte, length)
+	}
+
+	n, err := io.ReadFull(r, b[:length])
+	return b[:n], err
+}
+
+// ReadFrom provides a simple functional packet reader,
+// using the given byte slice as a backing array.
+//
+// To protect against potential denial of service attacks,
+// if the read packet length is longer than maxPacketLength,
+// then no packet data will be read, and ErrLongPacket will be returned.
+// (On 32-bit int architectures, all packets >= 2^31 in length
+// will return ErrLongPacket regardless of maxPacketLength.)
+//
+// If the read packet length is longer than cap(b),
+// then a throw-away slice will allocated to meet the exact packet length.
+// This can be used to limit the length of reused buffers,
+// while still allowing reception of occasional large packets.
+//
+// The Data field may alias the passed in byte slice,
+// so the byte slice passed in should not be reused before RawPacket.Reset().
+func (p *RawPacket) ReadFrom(r io.Reader, b []byte, maxPacketLength uint32) error {
+	b, err := readPacket(r, b, maxPacketLength)
+	if err != nil {
+		return err
+	}
+
+	return p.UnmarshalFrom(NewBuffer(b))
+}
+
+// RequestPacket implements the general packet format from draft-ietf-secsh-filexfer-02
+// but also automatically decode/encodes valid request packets (2 < type < 100 || type == 200).
+//
+// RequestPacket is intended for use in servers receiving requests,
+// where any arbitrary request may be received, and so decoding them automatically
+// is useful.
+//
+// For clients expecting to receive specific response packet types,
+// where automatic unmarshaling of the packet body does not make sense,
+// use RawPacket.
+//
+// Defined in https://tools.ietf.org/html/draft-ietf-secsh-filexfer-02#section-3
+type RequestPacket struct {
+	RequestID uint32
+
+	Request Packet
+}
+
+// Type returns the SSH_FXP_xy value associated with the underlying packet.
+func (p *RequestPacket) Type() PacketType {
+	return p.Request.Type()
+}
+
+// Reset clears the pointers and reference-semantic variables in RequestPacket,
+// releasing underlying resources, and making them and the RequestPacket suitable to be reused,
+// so long as no other references have been kept.
+func (p *RequestPacket) Reset() {
+	p.Request = nil
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+//
+// The internal p.RequestID is overridden by the reqid argument.
+func (p *RequestPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	if p.Request == nil {
+		return nil, nil, errors.New("empty request packet")
+	}
+
+	return p.Request.MarshalPacket(reqid, b)
+}
+
+// MarshalBinary returns p as the binary encoding of p.
+//
+// This is a convenience implementation primarily intended for tests,
+// because it is inefficient with allocations.
+func (p *RequestPacket) MarshalBinary() ([]byte, error) {
+	return ComposePacket(p.MarshalPacket(p.RequestID, nil))
+}
+
+// UnmarshalFrom decodes a RequestPacket from the given Buffer into p.
+//
+// The Request field may alias the passed in Buffer, (e.g. SSH_FXP_WRITE),
+// so the buffer passed in should not be reused before RequestPacket.Reset().
+func (p *RequestPacket) UnmarshalFrom(buf *Buffer) error {
+	typ, err := buf.ConsumeUint8()
+	if err != nil {
+		return err
+	}
+
+	p.Request, err = newPacketFromType(PacketType(typ))
+	if err != nil {
+		return err
+	}
+
+	if p.RequestID, err = buf.ConsumeUint32(); err != nil {
+		return err
+	}
+
+	return p.Request.UnmarshalPacketBody(buf)
+}
+
+// UnmarshalBinary decodes a full request packet out of the given data.
+// It is assumed that the uint32(length) has already been consumed to receive the data.
+//
+// This is a convenience implementation primarily intended for tests,
+// because this must clone the given data byte slice,
+// as Request is not allowed to alias any part of the data byte slice.
+func (p *RequestPacket) UnmarshalBinary(data []byte) error {
+	clone := make([]byte, len(data))
+	n := copy(clone, data)
+	return p.UnmarshalFrom(NewBuffer(clone[:n]))
+}
+
+// ReadFrom provides a simple functional packet reader,
+// using the given byte slice as a backing array.
+//
+// To protect against potential denial of service attacks,
+// if the read packet length is longer than maxPacketLength,
+// then no packet data will be read, and ErrLongPacket will be returned.
+// (On 32-bit int architectures, all packets >= 2^31 in length
+// will return ErrLongPacket regardless of maxPacketLength.)
+//
+// If the read packet length is longer than cap(b),
+// then a throw-away slice will allocated to meet the exact packet length.
+// This can be used to limit the length of reused buffers,
+// while still allowing reception of occasional large packets.
+//
+// The Request field may alias the passed in byte slice,
+// so the byte slice passed in should not be reused before RawPacket.Reset().
+func (p *RequestPacket) ReadFrom(r io.Reader, b []byte, maxPacketLength uint32) error {
+	b, err := readPacket(r, b, maxPacketLength)
+	if err != nil {
+		return err
+	}
+
+	return p.UnmarshalFrom(NewBuffer(b))
+}

vendor/github.com/pkg/sftp/internal/encoding/ssh/filexfer/path_packets.go

@@ -0,0 +1,368 @@
+package filexfer
+
+// LStatPacket defines the SSH_FXP_LSTAT packet.
+type LStatPacket struct {
+	Path string
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *LStatPacket) Type() PacketType {
+	return PacketTypeLStat
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *LStatPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 + len(p.Path) // string(path)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeLStat, reqid)
+	buf.AppendString(p.Path)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *LStatPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Path, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// SetstatPacket defines the SSH_FXP_SETSTAT packet.
+type SetstatPacket struct {
+	Path  string
+	Attrs Attributes
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *SetstatPacket) Type() PacketType {
+	return PacketTypeSetstat
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *SetstatPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 + len(p.Path) + p.Attrs.Len() // string(path) + ATTRS(attrs)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeSetstat, reqid)
+	buf.AppendString(p.Path)
+
+	p.Attrs.MarshalInto(buf)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *SetstatPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Path, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return p.Attrs.UnmarshalFrom(buf)
+}
+
+// RemovePacket defines the SSH_FXP_REMOVE packet.
+type RemovePacket struct {
+	Path string
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *RemovePacket) Type() PacketType {
+	return PacketTypeRemove
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *RemovePacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 + len(p.Path) // string(path)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeRemove, reqid)
+	buf.AppendString(p.Path)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *RemovePacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Path, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// MkdirPacket defines the SSH_FXP_MKDIR packet.
+type MkdirPacket struct {
+	Path  string
+	Attrs Attributes
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *MkdirPacket) Type() PacketType {
+	return PacketTypeMkdir
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *MkdirPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 + len(p.Path) + p.Attrs.Len() // string(path) + ATTRS(attrs)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeMkdir, reqid)
+	buf.AppendString(p.Path)
+
+	p.Attrs.MarshalInto(buf)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *MkdirPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Path, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return p.Attrs.UnmarshalFrom(buf)
+}
+
+// RmdirPacket defines the SSH_FXP_RMDIR packet.
+type RmdirPacket struct {
+	Path string
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *RmdirPacket) Type() PacketType {
+	return PacketTypeRmdir
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *RmdirPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 + len(p.Path) // string(path)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeRmdir, reqid)
+	buf.AppendString(p.Path)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *RmdirPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Path, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// RealPathPacket defines the SSH_FXP_REALPATH packet.
+type RealPathPacket struct {
+	Path string
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *RealPathPacket) Type() PacketType {
+	return PacketTypeRealPath
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *RealPathPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 + len(p.Path) // string(path)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeRealPath, reqid)
+	buf.AppendString(p.Path)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *RealPathPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Path, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// StatPacket defines the SSH_FXP_STAT packet.
+type StatPacket struct {
+	Path string
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *StatPacket) Type() PacketType {
+	return PacketTypeStat
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *StatPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 + len(p.Path) // string(path)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeStat, reqid)
+	buf.AppendString(p.Path)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *StatPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Path, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// RenamePacket defines the SSH_FXP_RENAME packet.
+type RenamePacket struct {
+	OldPath string
+	NewPath string
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *RenamePacket) Type() PacketType {
+	return PacketTypeRename
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *RenamePacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		// string(oldpath) + string(newpath)
+		size := 4 + len(p.OldPath) + 4 + len(p.NewPath)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeRename, reqid)
+	buf.AppendString(p.OldPath)
+	buf.AppendString(p.NewPath)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *RenamePacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.OldPath, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	if p.NewPath, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// ReadLinkPacket defines the SSH_FXP_READLINK packet.
+type ReadLinkPacket struct {
+	Path string
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *ReadLinkPacket) Type() PacketType {
+	return PacketTypeReadLink
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *ReadLinkPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 + len(p.Path) // string(path)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeReadLink, reqid)
+	buf.AppendString(p.Path)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *ReadLinkPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Path, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// SymlinkPacket defines the SSH_FXP_SYMLINK packet.
+//
+// The order of the arguments to the SSH_FXP_SYMLINK method was inadvertently reversed.
+// Unfortunately, the reversal was not noticed until the server was widely deployed.
+// Covered in Section 3.1 of https://github.com/openssh/openssh-portable/blob/master/PROTOCOL
+type SymlinkPacket struct {
+	LinkPath   string
+	TargetPath string
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *SymlinkPacket) Type() PacketType {
+	return PacketTypeSymlink
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *SymlinkPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		// string(targetpath) + string(linkpath)
+		size := 4 + len(p.TargetPath) + 4 + len(p.LinkPath)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeSymlink, reqid)
+
+	// Arguments were inadvertently reversed.
+	buf.AppendString(p.TargetPath)
+	buf.AppendString(p.LinkPath)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *SymlinkPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	// Arguments were inadvertently reversed.
+	if p.TargetPath, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	if p.LinkPath, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}

vendor/github.com/pkg/sftp/internal/encoding/ssh/filexfer/permissions.go

@@ -0,0 +1,114 @@
+package filexfer
+
+// FileMode represents a file’s mode and permission bits.
+// The bits are defined according to POSIX standards,
+// and may not apply to the OS being built for.
+type FileMode uint32
+
+// Permission flags, defined here to avoid potential inconsistencies in individual OS implementations.
+const (
+	ModePerm       FileMode = 0o0777 // S_IRWXU | S_IRWXG | S_IRWXO
+	ModeUserRead   FileMode = 0o0400 // S_IRUSR
+	ModeUserWrite  FileMode = 0o0200 // S_IWUSR
+	ModeUserExec   FileMode = 0o0100 // S_IXUSR
+	ModeGroupRead  FileMode = 0o0040 // S_IRGRP
+	ModeGroupWrite FileMode = 0o0020 // S_IWGRP
+	ModeGroupExec  FileMode = 0o0010 // S_IXGRP
+	ModeOtherRead  FileMode = 0o0004 // S_IROTH
+	ModeOtherWrite FileMode = 0o0002 // S_IWOTH
+	ModeOtherExec  FileMode = 0o0001 // S_IXOTH
+
+	ModeSetUID FileMode = 0o4000 // S_ISUID
+	ModeSetGID FileMode = 0o2000 // S_ISGID
+	ModeSticky FileMode = 0o1000 // S_ISVTX
+
+	ModeType       FileMode = 0xF000 // S_IFMT
+	ModeNamedPipe  FileMode = 0x1000 // S_IFIFO
+	ModeCharDevice FileMode = 0x2000 // S_IFCHR
+	ModeDir        FileMode = 0x4000 // S_IFDIR
+	ModeDevice     FileMode = 0x6000 // S_IFBLK
+	ModeRegular    FileMode = 0x8000 // S_IFREG
+	ModeSymlink    FileMode = 0xA000 // S_IFLNK
+	ModeSocket     FileMode = 0xC000 // S_IFSOCK
+)
+
+// IsDir reports whether m describes a directory.
+// That is, it tests for m.Type() == ModeDir.
+func (m FileMode) IsDir() bool {
+	return (m & ModeType) == ModeDir
+}
+
+// IsRegular reports whether m describes a regular file.
+// That is, it tests for m.Type() == ModeRegular
+func (m FileMode) IsRegular() bool {
+	return (m & ModeType) == ModeRegular
+}
+
+// Perm returns the POSIX permission bits in m (m & ModePerm).
+func (m FileMode) Perm() FileMode {
+	return (m & ModePerm)
+}
+
+// Type returns the type bits in m (m & ModeType).
+func (m FileMode) Type() FileMode {
+	return (m & ModeType)
+}
+
+// String returns a `-rwxrwxrwx` style string representing the `ls -l` POSIX permissions string.
+func (m FileMode) String() string {
+	var buf [10]byte
+
+	switch m.Type() {
+	case ModeRegular:
+		buf[0] = '-'
+	case ModeDir:
+		buf[0] = 'd'
+	case ModeSymlink:
+		buf[0] = 'l'
+	case ModeDevice:
+		buf[0] = 'b'
+	case ModeCharDevice:
+		buf[0] = 'c'
+	case ModeNamedPipe:
+		buf[0] = 'p'
+	case ModeSocket:
+		buf[0] = 's'
+	default:
+		buf[0] = '?'
+	}
+
+	const rwx = "rwxrwxrwx"
+	for i, c := range rwx {
+		if m&(1<<uint(9-1-i)) != 0 {
+			buf[i+1] = byte(c)
+		} else {
+			buf[i+1] = '-'
+		}
+	}
+
+	if m&ModeSetUID != 0 {
+		if buf[3] == 'x' {
+			buf[3] = 's'
+		} else {
+			buf[3] = 'S'
+		}
+	}
+
+	if m&ModeSetGID != 0 {
+		if buf[6] == 'x' {
+			buf[6] = 's'
+		} else {
+			buf[6] = 'S'
+		}
+	}
+
+	if m&ModeSticky != 0 {
+		if buf[9] == 'x' {
+			buf[9] = 't'
+		} else {
+			buf[9] = 'T'
+		}
+	}
+
+	return string(buf[:])
+}

vendor/github.com/pkg/sftp/internal/encoding/ssh/filexfer/response_packets.go

@@ -0,0 +1,243 @@
+package filexfer
+
+import (
+	"fmt"
+)
+
+// StatusPacket defines the SSH_FXP_STATUS packet.
+//
+// Specified in https://tools.ietf.org/html/draft-ietf-secsh-filexfer-02#section-7
+type StatusPacket struct {
+	StatusCode   Status
+	ErrorMessage string
+	LanguageTag  string
+}
+
+// Error makes StatusPacket an error type.
+func (p *StatusPacket) Error() string {
+	if p.ErrorMessage == "" {
+		return "sftp: " + p.StatusCode.String()
+	}
+
+	return fmt.Sprintf("sftp: %q (%s)", p.ErrorMessage, p.StatusCode)
+}
+
+// Is returns true if target is a StatusPacket with the same StatusCode,
+// or target is a Status code which is the same as SatusCode.
+func (p *StatusPacket) Is(target error) bool {
+	if target, ok := target.(*StatusPacket); ok {
+		return p.StatusCode == target.StatusCode
+	}
+
+	return p.StatusCode == target
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *StatusPacket) Type() PacketType {
+	return PacketTypeStatus
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *StatusPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		// uint32(error/status code) + string(error message) + string(language tag)
+		size := 4 + 4 + len(p.ErrorMessage) + 4 + len(p.LanguageTag)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeStatus, reqid)
+	buf.AppendUint32(uint32(p.StatusCode))
+	buf.AppendString(p.ErrorMessage)
+	buf.AppendString(p.LanguageTag)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *StatusPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	statusCode, err := buf.ConsumeUint32()
+	if err != nil {
+		return err
+	}
+	p.StatusCode = Status(statusCode)
+
+	if p.ErrorMessage, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	if p.LanguageTag, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// HandlePacket defines the SSH_FXP_HANDLE packet.
+type HandlePacket struct {
+	Handle string
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *HandlePacket) Type() PacketType {
+	return PacketTypeHandle
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *HandlePacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 + len(p.Handle) // string(handle)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeHandle, reqid)
+	buf.AppendString(p.Handle)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *HandlePacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	if p.Handle, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// DataPacket defines the SSH_FXP_DATA packet.
+type DataPacket struct {
+	Data []byte
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *DataPacket) Type() PacketType {
+	return PacketTypeData
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *DataPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 // uint32(len(data)); data content in payload
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeData, reqid)
+	buf.AppendUint32(uint32(len(p.Data)))
+
+	return buf.Packet(p.Data)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+//
+// If p.Data is already populated, and of sufficient length to hold the data,
+// then this will copy the data into that byte slice.
+//
+// If p.Data has a length insufficient to hold the data,
+// then this will make a new slice of sufficient length, and copy the data into that.
+//
+// This means this _does not_ alias any of the data buffer that is passed in.
+func (p *DataPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	data, err := buf.ConsumeByteSlice()
+	if err != nil {
+		return err
+	}
+
+	if len(p.Data) < len(data) {
+		p.Data = make([]byte, len(data))
+	}
+
+	n := copy(p.Data, data)
+	p.Data = p.Data[:n]
+	return nil
+}
+
+// NamePacket defines the SSH_FXP_NAME packet.
+type NamePacket struct {
+	Entries []*NameEntry
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *NamePacket) Type() PacketType {
+	return PacketTypeName
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *NamePacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := 4 // uint32(len(entries))
+
+		for _, e := range p.Entries {
+			size += e.Len()
+		}
+
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeName, reqid)
+	buf.AppendUint32(uint32(len(p.Entries)))
+
+	for _, e := range p.Entries {
+		e.MarshalInto(buf)
+	}
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *NamePacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	count, err := buf.ConsumeUint32()
+	if err != nil {
+		return err
+	}
+
+	p.Entries = make([]*NameEntry, 0, count)
+
+	for i := uint32(0); i < count; i++ {
+		var e NameEntry
+		if err := e.UnmarshalFrom(buf); err != nil {
+			return err
+		}
+
+		p.Entries = append(p.Entries, &e)
+	}
+
+	return nil
+}
+
+// AttrsPacket defines the SSH_FXP_ATTRS packet.
+type AttrsPacket struct {
+	Attrs Attributes
+}
+
+// Type returns the SSH_FXP_xy value associated with this packet type.
+func (p *AttrsPacket) Type() PacketType {
+	return PacketTypeAttrs
+}
+
+// MarshalPacket returns p as a two-part binary encoding of p.
+func (p *AttrsPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	buf := NewBuffer(b)
+	if buf.Cap() < 9 {
+		size := p.Attrs.Len() // ATTRS(attrs)
+		buf = NewMarshalBuffer(size)
+	}
+
+	buf.StartPacket(PacketTypeAttrs, reqid)
+	p.Attrs.MarshalInto(buf)
+
+	return buf.Packet(payload)
+}
+
+// UnmarshalPacketBody unmarshals the packet body from the given Buffer.
+// It is assumed that the uint32(request-id) has already been consumed.
+func (p *AttrsPacket) UnmarshalPacketBody(buf *Buffer) (err error) {
+	return p.Attrs.UnmarshalFrom(buf)
+}