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errors.go
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/
errors.go
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package gateway
import (
"context"
"errors"
"fmt"
"net/http"
"strconv"
"strings"
"time"
"github.com/ipfs/boxo/gateway/assets"
"github.com/ipfs/boxo/path/resolver"
"github.com/ipfs/go-cid"
"github.com/ipld/go-ipld-prime/datamodel"
)
var (
ErrInternalServerError = NewErrorStatusCodeFromStatus(http.StatusInternalServerError)
ErrGatewayTimeout = NewErrorStatusCodeFromStatus(http.StatusGatewayTimeout)
ErrBadGateway = NewErrorStatusCodeFromStatus(http.StatusBadGateway)
ErrServiceUnavailable = NewErrorStatusCodeFromStatus(http.StatusServiceUnavailable)
ErrTooManyRequests = NewErrorStatusCodeFromStatus(http.StatusTooManyRequests)
)
// ErrorRetryAfter wraps any error with "retry after" hint. When an error of this type
// returned to the gateway handler by an [IPFSBackend], the retry after value will be
// passed to the HTTP client in a [Retry-After] HTTP header.
//
// [Retry-After]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Retry-After
type ErrorRetryAfter struct {
Err error
RetryAfter time.Duration
}
func NewErrorRetryAfter(err error, retryAfter time.Duration) *ErrorRetryAfter {
if err == nil {
err = ErrServiceUnavailable
}
if retryAfter < 0 {
retryAfter = 0
}
return &ErrorRetryAfter{
RetryAfter: retryAfter,
Err: err,
}
}
func (e *ErrorRetryAfter) Error() string {
var text string
if e.Err != nil {
text = e.Err.Error()
}
if e.RetryAfter != 0 {
text += ", retry after " + e.humanizedRoundSeconds()
}
return text
}
func (e *ErrorRetryAfter) Unwrap() error {
return e.Err
}
func (e *ErrorRetryAfter) Is(err error) bool {
switch err.(type) {
case *ErrorRetryAfter:
return true
default:
return false
}
}
// RetryAfterHeader returns the [Retry-After] header value as a string, representing the number
// of seconds to wait before making a new request, rounded to the nearest second.
// This function follows the [Retry-After] header definition as specified in RFC 9110.
//
// [Retry-After]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Retry-After
func (e *ErrorRetryAfter) RetryAfterHeader() string {
return strconv.Itoa(int(e.roundSeconds().Seconds()))
}
func (e *ErrorRetryAfter) roundSeconds() time.Duration {
return e.RetryAfter.Round(time.Second)
}
func (e *ErrorRetryAfter) humanizedRoundSeconds() string {
return e.roundSeconds().String()
}
// ErrorStatusCode wraps any error with a specific HTTP status code. When an error
// of this type is returned to the gateway handler by an [IPFSBackend], the status
// code will be used for the response status.
type ErrorStatusCode struct {
StatusCode int
Err error
}
func NewErrorStatusCodeFromStatus(statusCode int) *ErrorStatusCode {
return NewErrorStatusCode(errors.New(http.StatusText(statusCode)), statusCode)
}
func NewErrorStatusCode(err error, statusCode int) *ErrorStatusCode {
return &ErrorStatusCode{
Err: err,
StatusCode: statusCode,
}
}
func (e *ErrorStatusCode) Is(err error) bool {
switch err.(type) {
case *ErrorStatusCode:
return true
default:
return false
}
}
func (e *ErrorStatusCode) Error() string {
var text string
if e.Err != nil {
text = e.Err.Error()
}
return text
}
func (e *ErrorStatusCode) Unwrap() error {
return e.Err
}
func webError(w http.ResponseWriter, r *http.Request, c *Config, err error, defaultCode int) {
code := defaultCode
// Pass Retry-After hint to the client
var era *ErrorRetryAfter
if errors.As(err, &era) {
if era.RetryAfter > 0 {
w.Header().Set("Retry-After", era.RetryAfterHeader())
// Adjust defaultCode if needed
if code != http.StatusTooManyRequests && code != http.StatusServiceUnavailable {
code = http.StatusTooManyRequests
}
}
err = era.Unwrap()
}
// Handle status code
switch {
case errors.Is(err, &cid.ErrInvalidCid{}):
code = http.StatusBadRequest
case isErrNotFound(err):
code = http.StatusNotFound
case isErrContentBlocked(err):
code = http.StatusGone
case errors.Is(err, context.DeadlineExceeded):
code = http.StatusGatewayTimeout
}
// Handle explicit code in ErrorResponse
var gwErr *ErrorStatusCode
if errors.As(err, &gwErr) {
code = gwErr.StatusCode
}
acceptsHTML := !c.DisableHTMLErrors && strings.Contains(r.Header.Get("Accept"), "text/html")
if acceptsHTML {
w.Header().Set("Content-Type", "text/html")
w.WriteHeader(code)
err = assets.ErrorTemplate.Execute(w, assets.ErrorTemplateData{
GlobalData: assets.GlobalData{
Menu: c.Menu,
},
StatusCode: code,
StatusText: http.StatusText(code),
Error: err.Error(),
})
if err != nil {
_, _ = w.Write([]byte(fmt.Sprintf("error during body generation: %v", err)))
}
} else {
http.Error(w, err.Error(), code)
}
}
// isErrNotFound returns true for IPLD errors that should return 4xx errors (e.g. the path doesn't exist, the data is
// the wrong type, etc.), rather than issues with just finding and retrieving the data.
func isErrNotFound(err error) bool {
if errors.Is(err, &resolver.ErrNoLink{}) {
return true
}
// Checks if err is of a type that does not implement the .Is interface and
// cannot be directly compared to. Therefore, errors.Is cannot be used.
for {
_, ok := err.(datamodel.ErrWrongKind)
if ok {
return true
}
_, ok = err.(datamodel.ErrNotExists)
if ok {
return true
}
err = errors.Unwrap(err)
if err == nil {
return false
}
}
}
// isErrContentBlocked returns true for content filtering system errors
func isErrContentBlocked(err error) bool {
// TODO: we match error message to avoid pulling nopfs as a dependency
// Ref. https://github.com/ipfs-shipyard/nopfs/blob/cde3b5ba964c13e977f4a95f3bd8ca7d7710fbda/status.go#L87-L89
return strings.Contains(err.Error(), "blocked and cannot be provided")
}