add comments and fix warning for main command and pkg apdu

apdu/command.go

@@ -5,6 +5,7 @@ import (
 	"encoding/binary"
 )
 
+// Command struct represent the data sent as an APDU command with CLA, Ins, P1, P2, Lc, Data, and Le.
 type Command struct {
 	Cla        uint8
 	Ins        uint8
@@ -15,6 +16,7 @@ type Command struct {
 	requiresLe bool
 }
 
+// NewCommand returns a new apdu Command.
 func NewCommand(cla, ins, p1, p2 uint8, data []byte) *Command {
 	return &Command{
 		Cla:        cla,
@@ -26,15 +28,18 @@ func NewCommand(cla, ins, p1, p2 uint8, data []byte) *Command {
 	}
 }
 
+// SetLe sets the expected Le value and makes sure the Le value is sent in the apdu Command.
 func (c *Command) SetLe(le uint8) {
 	c.requiresLe = true
 	c.le = le
 }
 
+// Le returns if Le is set and its value.
 func (c *Command) Le() (bool, uint8) {
 	return c.requiresLe, c.le
 }
 
+// Serialize serielizes the command into a raw bytes sequence.
 func (c *Command) Serialize() ([]byte, error) {
 	buf := new(bytes.Buffer)
 

apdu/response.go

@@ -8,14 +8,17 @@ import (
 )
 
 const (
+	// SwOK is returned from smartcards as a positive response code.
 	SwOK = 0x9000
 )
 
+// ErrBadResponse defines an error conaining the returned Sw code and a description message.
 type ErrBadResponse struct {
 	sw      uint16
 	message string
 }
 
+// NewErrBadResponse returns a ErrBadResponse with the specified sw and message values.
 func NewErrBadResponse(sw uint16, message string) *ErrBadResponse {
 	return &ErrBadResponse{
 		sw:      sw,
@@ -23,10 +26,12 @@ func NewErrBadResponse(sw uint16, message string) *ErrBadResponse {
 	}
 }
 
+// Error implements the error interface.
 func (e *ErrBadResponse) Error() string {
 	return fmt.Sprintf("bad response %x: %s", e.sw, e.message)
 }
 
+// Response represents a struct containing the smartcard response fields.
 type Response struct {
 	Data []byte
 	Sw1  uint8
@@ -34,8 +39,10 @@ type Response struct {
 	Sw   uint16
 }
 
+// ErrBadRawResponse is an error returned by ParseResponse in case the response data is not long enough.
 var ErrBadRawResponse = errors.New("response data must be at least 2 bytes")
 
+// ParseResponse parses a raw response and return a Response.
 func ParseResponse(data []byte) (*Response, error) {
 	r := &Response{}
 	return r, r.deserialize(data)
@@ -66,6 +73,7 @@ func (r *Response) deserialize(data []byte) error {
 	return nil
 }
 
+// IsOK returns true if the response Sw code is 0x9000.
 func (r *Response) IsOK() bool {
 	return r.Sw == SwOK
 }

apdu/utils.go

@@ -6,14 +6,17 @@ import (
 	"io"
 )
 
+// ErrTagNotFound is an error returned if a tag is not found in a TLV sequence.
 type ErrTagNotFound struct {
 	tag uint8
 }
 
+// Error implements the error interface
 func (e *ErrTagNotFound) Error() string {
 	return fmt.Sprintf("tag %x not found", e.tag)
 }
 
+// FindTag searches for a tag value within a TLV sequence.
 func FindTag(raw []byte, tags ...uint8) ([]byte, error) {
 	if len(tags) == 0 {
 		return raw, nil