errors.go

Documentation: oras.land/oras-go/pkg/registry/remote/internal/errutil

     1  /*
     2  Copyright The ORAS Authors.
     3  Licensed under the Apache License, Version 2.0 (the "License");
     4  you may not use this file except in compliance with the License.
     5  You may obtain a copy of the License at
     6  
     7  http://www.apache.org/licenses/LICENSE-2.0
     8  
     9  Unless required by applicable law or agreed to in writing, software
    10  distributed under the License is distributed on an "AS IS" BASIS,
    11  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  See the License for the specific language governing permissions and
    13  limitations under the License.
    14  */
    15  package errutil
    16  
    17  import (
    18  	"encoding/json"
    19  	"fmt"
    20  	"io"
    21  	"net/http"
    22  	"strings"
    23  	"unicode"
    24  )
    25  
    26  // maxErrorBytes specifies the default limit on how many response bytes are
    27  // allowed in the server's error response.
    28  // A typical error message is around 200 bytes. Hence, 8 KiB should be
    29  // sufficient.
    30  var maxErrorBytes int64 = 8 * 1024 // 8 KiB
    31  
    32  // requestError contains a single error.
    33  type requestError struct {
    34  	Code    string `json:"code"`
    35  	Message string `json:"message"`
    36  }
    37  
    38  // Error returns a error string describing the error.
    39  func (e requestError) Error() string {
    40  	code := strings.Map(func(r rune) rune {
    41  		if r == '_' {
    42  			return ' '
    43  		}
    44  		return unicode.ToLower(r)
    45  	}, e.Code)
    46  	if e.Message == "" {
    47  		return code
    48  	}
    49  	return fmt.Sprintf("%s: %s", code, e.Message)
    50  }
    51  
    52  // requestErrors is a bundle of requestError.
    53  type requestErrors []requestError
    54  
    55  // Error returns a error string describing the error.
    56  func (errs requestErrors) Error() string {
    57  	switch len(errs) {
    58  	case 0:
    59  		return "<nil>"
    60  	case 1:
    61  		return errs[0].Error()
    62  	}
    63  	var errmsgs []string
    64  	for _, err := range errs {
    65  		errmsgs = append(errmsgs, err.Error())
    66  	}
    67  	return strings.Join(errmsgs, "; ")
    68  }
    69  
    70  // ParseErrorResponse parses the error returned by the remote registry.
    71  func ParseErrorResponse(resp *http.Response) error {
    72  	var errmsg string
    73  	var body struct {
    74  		Errors requestErrors `json:"errors"`
    75  	}
    76  	lr := io.LimitReader(resp.Body, maxErrorBytes)
    77  	if err := json.NewDecoder(lr).Decode(&body); err == nil && len(body.Errors) > 0 {
    78  		errmsg = body.Errors.Error()
    79  	} else {
    80  		errmsg = http.StatusText(resp.StatusCode)
    81  	}
    82  	return fmt.Errorf("%s %q: unexpected status code %d: %s", resp.Request.Method, resp.Request.URL, resp.StatusCode, errmsg)
    83  }
    84
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