80 lines
1.7 KiB
Go
80 lines
1.7 KiB
Go
package apdu
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import (
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"bytes"
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"encoding/binary"
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"errors"
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"fmt"
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)
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const (
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// SwOK is returned from smartcards as a positive response code.
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SwOK = 0x9000
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)
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// ErrBadResponse defines an error conaining the returned Sw code and a description message.
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type ErrBadResponse struct {
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Sw uint16
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message string
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}
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// NewErrBadResponse returns a ErrBadResponse with the specified sw and message values.
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func NewErrBadResponse(sw uint16, message string) *ErrBadResponse {
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return &ErrBadResponse{
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Sw: sw,
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message: message,
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}
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}
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// Error implements the error interface.
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func (e *ErrBadResponse) Error() string {
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return fmt.Sprintf("bad response %x: %s", e.Sw, e.message)
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}
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// Response represents a struct containing the smartcard response fields.
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type Response struct {
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Data []byte
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Sw1 uint8
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Sw2 uint8
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Sw uint16
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}
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// ErrBadRawResponse is an error returned by ParseResponse in case the response data is not long enough.
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var ErrBadRawResponse = errors.New("response data must be at least 2 bytes")
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// ParseResponse parses a raw response and return a Response.
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func ParseResponse(data []byte) (*Response, error) {
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r := &Response{}
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return r, r.deserialize(data)
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}
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func (r *Response) deserialize(data []byte) error {
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if len(data) < 2 {
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return ErrBadRawResponse
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}
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r.Data = make([]byte, len(data)-2)
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buf := bytes.NewReader(data)
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if err := binary.Read(buf, binary.BigEndian, &r.Data); err != nil {
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return err
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}
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if err := binary.Read(buf, binary.BigEndian, &r.Sw1); err != nil {
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return err
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}
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if err := binary.Read(buf, binary.BigEndian, &r.Sw2); err != nil {
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return err
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}
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r.Sw = (uint16(r.Sw1) << 8) | uint16(r.Sw2)
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return nil
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}
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// IsOK returns true if the response Sw code is 0x9000.
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func (r *Response) IsOK() bool {
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return r.Sw == SwOK
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}
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