Function CheckResponse

github/github.go:1719–1787

CheckResponse checks the API response for errors, and returns them if present. A response is considered an error if it has a status code outside the 200 range or equal to 202 Accepted. API error responses are expected to have response body, and a JSON response body that maps to [ErrorResponse]. The

(r *http.Response)

// *[TwoFactorAuthError] for two-factor authentication errors,
// and *[RedirectionError] for redirect status codes (only happens when ignoring redirections).
func CheckResponse(r *http.Response) error {
	if r.StatusCode == http.StatusAccepted {
		return &AcceptedError{}
	}
	if c := r.StatusCode; 200 <= c && c <= 299 {
		return nil
	}

	errorResponse := &ErrorResponse{Response: r}
	data, err := io.ReadAll(io.LimitReader(r.Body, maxErrorBodySize))
	if err == nil && data != nil {
		err = json.Unmarshal(data, errorResponse)
		if err != nil {
			// reset the response as if this never happened
			errorResponse = &ErrorResponse{Response: r}
		}
	}
	// Re-populate error response body because GitHub error responses are often
	// undocumented and inconsistent.
	// Issue #1136, #540.
	r.Body = io.NopCloser(bytes.NewBuffer(data))
	switch {
	case r.StatusCode == http.StatusUnauthorized && strings.HasPrefix(r.Header.Get(headerOTP), "required"):
		return (*TwoFactorAuthError)(errorResponse)
	// Primary rate limit exceeded: GitHub returns 403 or 429 with X-RateLimit-Remaining: 0
	// See: https://docs.github.com/rest/using-the-rest-api/rate-limits-for-the-rest-api?apiVersion=2022-11-28
	case (r.StatusCode == http.StatusForbidden || r.StatusCode == http.StatusTooManyRequests) &&
		r.Header.Get(HeaderRateRemaining) == "0":
		return &RateLimitError{
			Rate:     parseRate(r),
			Response: errorResponse.Response,
			Message:  errorResponse.Message,
		}
	// Secondary rate limit exceeded: GitHub returns 403 or 429 with specific documentation_url
	// See: https://docs.github.com/rest/using-the-rest-api/rate-limits-for-the-rest-api?apiVersion=2022-11-28#about-secondary-rate-limits
	case (r.StatusCode == http.StatusForbidden || r.StatusCode == http.StatusTooManyRequests) &&
		(strings.HasSuffix(errorResponse.DocumentationURL, "#abuse-rate-limits") ||
			strings.HasSuffix(errorResponse.DocumentationURL, "secondary-rate-limits")):
		abuseRateLimitError := &AbuseRateLimitError{
			Response: errorResponse.Response,
			Message:  errorResponse.Message,
		}
		if retryAfter := parseSecondaryRate(r); retryAfter != nil {
			abuseRateLimitError.RetryAfter = retryAfter
		}
		return abuseRateLimitError
	// Check that the status code is a redirection and return a sentinel error that can be used to handle special cases
	// where 302 is considered a successful result.
	// This should never happen with the default `CheckRedirect`, because it would return a `url.Error` that should be handled upstream.
	case r.StatusCode == http.StatusMovedPermanently ||
		r.StatusCode == http.StatusFound ||
		r.StatusCode == http.StatusSeeOther ||
		r.StatusCode == http.StatusTemporaryRedirect ||
		r.StatusCode == http.StatusPermanentRedirect:

		locationStr := r.Header.Get("Location")
		var location *url.URL
		if locationStr != "" {