certificates/errs/error.go

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package errs
import (
"encoding/json"
"fmt"
"net/http"
"github.com/pkg/errors"
)
// StatusCoder interface is used by errors that returns the HTTP response code.
type StatusCoder interface {
StatusCode() int
}
// StackTracer must be by those errors that return an stack trace.
type StackTracer interface {
StackTrace() errors.StackTrace
}
// Option modifies the Error type.
type Option func(e *Error) error
// WithMessage returns an Option that modifies the error by overwriting the
// message only if it is empty.
func WithMessage(format string, args ...interface{}) Option {
return func(e *Error) error {
if len(e.Msg) > 0 {
return e
}
e.Msg = fmt.Sprintf(format, args...)
return e
}
}
// Error represents the CA API errors.
type Error struct {
Status int
Err error
Msg string
}
// New returns a new Error. If the given error implements the StatusCoder
// interface we will ignore the given status.
func New(status int, err error, opts ...Option) error {
var e *Error
if sc, ok := err.(StatusCoder); ok {
e = &Error{Status: sc.StatusCode(), Err: err}
} else {
cause := errors.Cause(err)
if sc, ok := cause.(StatusCoder); ok {
e = &Error{Status: sc.StatusCode(), Err: err}
} else {
e = &Error{Status: status, Err: err}
}
}
for _, o := range opts {
o(e)
}
return e
}
// ErrorResponse represents an error in JSON format.
type ErrorResponse struct {
Status int `json:"status"`
Message string `json:"message"`
}
// Cause implements the errors.Causer interface and returns the original error.
func (e *Error) Cause() error {
return e.Err
}
// Error implements the error interface and returns the error string.
func (e *Error) Error() string {
return e.Err.Error()
}
// StatusCode implements the StatusCoder interface and returns the HTTP response
// code.
func (e *Error) StatusCode() int {
return e.Status
}
// Message returns a user friendly error, if one is set.
func (e *Error) Message() string {
if len(e.Msg) > 0 {
return e.Msg
}
return e.Err.Error()
}
// Wrap returns an error annotating err with a stack trace at the point Wrap is
// called, and the supplied message. If err is nil, Wrap returns nil.
func Wrap(status int, e error, m string, opts ...Option) error {
if e == nil {
return nil
}
if err, ok := e.(*Error); ok {
err.Err = errors.Wrap(err.Err, m)
e = err
} else {
e = errors.Wrap(e, m)
}
return StatusCodeError(status, e, opts...)
}
// Wrapf returns an error annotating err with a stack trace at the point Wrap is
// called, and the supplied message. If err is nil, Wrap returns nil.
func Wrapf(status int, e error, format string, args ...interface{}) error {
if e == nil {
return nil
}
var opts []Option
for i, arg := range args {
// Once we find the first Option, assume that all further arguments are Options.
if _, ok := arg.(Option); ok {
for _, a := range args[i:] {
// Ignore any arguments after the first Option that are not Options.
if opt, ok := a.(Option); ok {
opts = append(opts, opt)
}
}
args = args[:i]
break
}
}
if err, ok := e.(*Error); ok {
err.Err = errors.Wrapf(err.Err, format, args...)
e = err
} else {
e = errors.Wrapf(e, format, args...)
}
return StatusCodeError(status, e, opts...)
}
// MarshalJSON implements json.Marshaller interface for the Error struct.
func (e *Error) MarshalJSON() ([]byte, error) {
var msg string
if len(e.Msg) > 0 {
msg = e.Msg
} else {
msg = http.StatusText(e.Status)
}
return json.Marshal(&ErrorResponse{Status: e.Status, Message: msg})
}
// UnmarshalJSON implements json.Unmarshaler interface for the Error struct.
func (e *Error) UnmarshalJSON(data []byte) error {
var er ErrorResponse
if err := json.Unmarshal(data, &er); err != nil {
return err
}
e.Status = er.Status
e.Err = fmt.Errorf(er.Message)
return nil
}
// Format implements the fmt.Formatter interface.
func (e *Error) Format(f fmt.State, c rune) {
if err, ok := e.Err.(fmt.Formatter); ok {
err.Format(f, c)
return
}
fmt.Fprint(f, e.Err.Error())
}
// Messenger is a friendly message interface that errors can implement.
type Messenger interface {
Message() string
}
// StatusCodeError selects the proper error based on the status code.
func StatusCodeError(code int, e error, opts ...Option) error {
switch code {
case http.StatusBadRequest:
return BadRequest(e, opts...)
case http.StatusUnauthorized:
return Unauthorized(e, opts...)
case http.StatusForbidden:
return Forbidden(e, opts...)
case http.StatusInternalServerError:
return InternalServerError(e, opts...)
case http.StatusNotImplemented:
return NotImplemented(e, opts...)
default:
return UnexpectedError(code, e, opts...)
}
}
var seeLogs = "Please see the certificate authority logs for more info."
// InternalServerError returns a 500 error with the given error.
func InternalServerError(err error, opts ...Option) error {
if len(opts) == 0 {
opts = append(opts, WithMessage("The certificate authority encountered an Internal Server Error. "+seeLogs))
}
return New(http.StatusInternalServerError, err, opts...)
}
// NotImplemented returns a 501 error with the given error.
func NotImplemented(err error, opts ...Option) error {
if len(opts) == 0 {
opts = append(opts, WithMessage("The requested method is not implemented by the certificate authority. "+seeLogs))
}
return New(http.StatusNotImplemented, err, opts...)
}
// BadRequest returns an 400 error with the given error.
func BadRequest(err error, opts ...Option) error {
if len(opts) == 0 {
opts = append(opts, WithMessage("The request could not be completed due to being poorly formatted or "+
"missing critical data. "+seeLogs))
}
return New(http.StatusBadRequest, err, opts...)
}
// Unauthorized returns an 401 error with the given error.
func Unauthorized(err error, opts ...Option) error {
if len(opts) == 0 {
opts = append(opts, WithMessage("The request lacked necessary authorization to be completed. "+seeLogs))
}
return New(http.StatusUnauthorized, err, opts...)
}
// Forbidden returns an 403 error with the given error.
func Forbidden(err error, opts ...Option) error {
if len(opts) == 0 {
opts = append(opts, WithMessage("The request was Forbidden by the certificate authority. "+seeLogs))
}
return New(http.StatusForbidden, err, opts...)
}
// NotFound returns an 404 error with the given error.
func NotFound(err error, opts ...Option) error {
if len(opts) == 0 {
opts = append(opts, WithMessage("The requested resource could not be found. "+seeLogs))
}
return New(http.StatusNotFound, err, opts...)
}
// UnexpectedError will be used when the certificate authority makes an outgoing
// request and receives an unhandled status code.
func UnexpectedError(code int, err error, opts ...Option) error {
if len(opts) == 0 {
opts = append(opts, WithMessage("The certificate authority received an "+
"unexpected HTTP status code - '%d'. "+seeLogs, code))
}
return New(code, err, opts...)
}