github.com/m3db/m3@v1.5.0/src/x/net/http/errors.go (about)

     1  // Copyright (c) 2018 Uber Technologies, Inc.
     2  //
     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
     4  // of this software and associated documentation files (the "Software"), to deal
     5  // in the Software without restriction, including without limitation the rights
     6  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     7  // copies of the Software, and to permit persons to whom the Software is
     8  // furnished to do so, subject to the following conditions:
     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    18  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    19  // THE SOFTWARE.
    20  
    21  package xhttp
    22  
    23  import (
    24  	"context"
    25  	"encoding/json"
    26  	"errors"
    27  	"net/http"
    28  	"sync"
    29  
    30  	"github.com/prometheus/prometheus/promql"
    31  
    32  	"github.com/m3db/m3/src/dbnode/client"
    33  	xerrors "github.com/m3db/m3/src/x/errors"
    34  )
    35  
    36  // ErrorRewriteFn is a function for rewriting response error.
    37  type ErrorRewriteFn func(error) error
    38  
    39  var (
    40  	errorRewriteFn     ErrorRewriteFn = func(err error) error { return err }
    41  	errorRewriteFnLock sync.RWMutex
    42  )
    43  
    44  // Error is an HTTP JSON error that also sets a return status code.
    45  type Error interface {
    46  	// Fulfill error interface.
    47  	error
    48  
    49  	// Embedding ContainedError allows for the inner error
    50  	// to be retrieved with all existing error helpers.
    51  	xerrors.ContainedError
    52  
    53  	// Code returns the status code to return to end users.
    54  	Code() int
    55  }
    56  
    57  // NewError creates a new error with an explicit status code
    58  // which will override any wrapped error to return specifically
    59  // the exact error code desired.
    60  func NewError(err error, status int) Error {
    61  	return errorWithCode{err: err, status: status}
    62  }
    63  
    64  type errorWithCode struct {
    65  	err    error
    66  	status int
    67  }
    68  
    69  func (e errorWithCode) Error() string {
    70  	return e.err.Error()
    71  }
    72  
    73  func (e errorWithCode) InnerError() error {
    74  	return e.err
    75  }
    76  
    77  func (e errorWithCode) Code() int {
    78  	return e.status
    79  }
    80  
    81  // ErrorResponse is a generic response for an HTTP error.
    82  type ErrorResponse struct {
    83  	Status string `json:"status"`
    84  	Error  string `json:"error"`
    85  }
    86  
    87  type options struct {
    88  	response []byte
    89  }
    90  
    91  // WriteErrorOption is an option to pass to WriteError.
    92  type WriteErrorOption func(*options)
    93  
    94  // WithErrorResponse specifies a response to add the WriteError method.
    95  func WithErrorResponse(b []byte) WriteErrorOption {
    96  	return func(o *options) {
    97  		o.response = b
    98  	}
    99  }
   100  
   101  // WriteError will serve an HTTP error.
   102  func WriteError(w http.ResponseWriter, err error, opts ...WriteErrorOption) {
   103  	var o options
   104  	for _, fn := range opts {
   105  		fn(&o)
   106  	}
   107  
   108  	errorRewriteFnLock.RLock()
   109  	err = errorRewriteFn(err)
   110  	errorRewriteFnLock.RUnlock()
   111  
   112  	statusCode := getStatusCode(err)
   113  	if o.response == nil {
   114  		w.Header().Set(HeaderContentType, ContentTypeJSON)
   115  		w.WriteHeader(statusCode)
   116  		json.NewEncoder(w).Encode(ErrorResponse{Status: "error", Error: err.Error()}) //nolint:errcheck
   117  	} else {
   118  		w.WriteHeader(statusCode)
   119  		w.Write(o.response)
   120  	}
   121  }
   122  
   123  // SetErrorRewriteFn sets error rewrite function.
   124  func SetErrorRewriteFn(f ErrorRewriteFn) ErrorRewriteFn {
   125  	errorRewriteFnLock.Lock()
   126  	defer errorRewriteFnLock.Unlock()
   127  
   128  	res := errorRewriteFn
   129  	errorRewriteFn = f
   130  	return res
   131  }
   132  
   133  func getStatusCode(err error) int {
   134  	switch v := err.(type) {
   135  	case Error:
   136  		return v.Code()
   137  	case error:
   138  		if xerrors.IsInvalidParams(v) {
   139  			return http.StatusBadRequest
   140  		} else if errors.Is(err, context.Canceled) {
   141  			// This status code was coined by Nginx for exactly the same use case.
   142  			// https://httpstatuses.com/499
   143  			return 499
   144  		} else if errors.Is(err, context.DeadlineExceeded) || client.IsTimeoutError(err) {
   145  			return http.StatusGatewayTimeout
   146  			// Also check for prom errors, which can be either a cancellation or a timeout.
   147  		} else if _, ok := err.(promql.ErrQueryCanceled); ok { // nolint:errorlint
   148  			return 499
   149  		}
   150  	}
   151  	return http.StatusInternalServerError
   152  }
   153  
   154  // IsClientError returns true if this error would result in 4xx status code.
   155  func IsClientError(err error) bool {
   156  	code := getStatusCode(err)
   157  	return code >= 400 && code < 500
   158  }