Working on SFTP

1 files changed, 54 insertions, 0 deletions

diff --git a/internal/encoding/ssh/filexfer/filexfer.go b/internal/encoding/ssh/filexfer/filexfer.go
new file mode 100644
index 0000000..1e5abf7
--- /dev/null
+++ b/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
+)