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