gitee.com/ks-custle/core-gm@v0.0.0-20230922171213-b83bdd97b62c/prometheus/common/internal/bitbucket.org/ww/goautoneg/autoneg.go (about)

     1  /*
     2  Copyright (c) 2011, Open Knowledge Foundation Ltd.
     3  All rights reserved.
     4  
     5  HTTP Content-Type Autonegotiation.
     6  
     7  The functions in this package implement the behaviour specified in
     8  http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
     9  
    10  Redistribution and use in source and binary forms, with or without
    11  modification, are permitted provided that the following conditions are
    12  met:
    13  
    14      Redistributions of source code must retain the above copyright
    15      notice, this list of conditions and the following disclaimer.
    16  
    17      Redistributions in binary form must reproduce the above copyright
    18      notice, this list of conditions and the following disclaimer in
    19      the documentation and/or other materials provided with the
    20      distribution.
    21  
    22      Neither the name of the Open Knowledge Foundation Ltd. nor the
    23      names of its contributors may be used to endorse or promote
    24      products derived from this software without specific prior written
    25      permission.
    26  
    27  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    28  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    29  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    30  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    31  HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    32  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    33  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    34  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    35  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    36  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    37  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    38  
    39  
    40  */
    41  package goautoneg
    42  
    43  import (
    44  	"sort"
    45  	"strconv"
    46  	"strings"
    47  )
    48  
    49  // Structure to represent a clause in an HTTP Accept Header
    50  type Accept struct {
    51  	Type, SubType string
    52  	Q             float64
    53  	Params        map[string]string
    54  }
    55  
    56  // For internal use, so that we can use the sort interface
    57  type accept_slice []Accept
    58  
    59  func (accept accept_slice) Len() int {
    60  	slice := []Accept(accept)
    61  	return len(slice)
    62  }
    63  
    64  func (accept accept_slice) Less(i, j int) bool {
    65  	slice := []Accept(accept)
    66  	ai, aj := slice[i], slice[j]
    67  	if ai.Q > aj.Q {
    68  		return true
    69  	}
    70  	if ai.Type != "*" && aj.Type == "*" {
    71  		return true
    72  	}
    73  	if ai.SubType != "*" && aj.SubType == "*" {
    74  		return true
    75  	}
    76  	return false
    77  }
    78  
    79  func (accept accept_slice) Swap(i, j int) {
    80  	slice := []Accept(accept)
    81  	slice[i], slice[j] = slice[j], slice[i]
    82  }
    83  
    84  // Parse an Accept Header string returning a sorted list
    85  // of clauses
    86  func ParseAccept(header string) (accept []Accept) {
    87  	parts := strings.Split(header, ",")
    88  	accept = make([]Accept, 0, len(parts))
    89  	for _, part := range parts {
    90  		part := strings.Trim(part, " ")
    91  
    92  		a := Accept{}
    93  		a.Params = make(map[string]string)
    94  		a.Q = 1.0
    95  
    96  		mrp := strings.Split(part, ";")
    97  
    98  		media_range := mrp[0]
    99  		sp := strings.Split(media_range, "/")
   100  		a.Type = strings.Trim(sp[0], " ")
   101  
   102  		switch {
   103  		case len(sp) == 1 && a.Type == "*":
   104  			a.SubType = "*"
   105  		case len(sp) == 2:
   106  			a.SubType = strings.Trim(sp[1], " ")
   107  		default:
   108  			continue
   109  		}
   110  
   111  		if len(mrp) == 1 {
   112  			accept = append(accept, a)
   113  			continue
   114  		}
   115  
   116  		for _, param := range mrp[1:] {
   117  			sp := strings.SplitN(param, "=", 2)
   118  			if len(sp) != 2 {
   119  				continue
   120  			}
   121  			token := strings.Trim(sp[0], " ")
   122  			if token == "q" {
   123  				a.Q, _ = strconv.ParseFloat(sp[1], 32)
   124  			} else {
   125  				a.Params[token] = strings.Trim(sp[1], " ")
   126  			}
   127  		}
   128  
   129  		accept = append(accept, a)
   130  	}
   131  
   132  	slice := accept_slice(accept)
   133  	sort.Sort(slice)
   134  
   135  	return
   136  }
   137  
   138  // Negotiate the most appropriate content_type given the accept header
   139  // and a list of alternatives.
   140  func Negotiate(header string, alternatives []string) (content_type string) {
   141  	asp := make([][]string, 0, len(alternatives))
   142  	for _, ctype := range alternatives {
   143  		asp = append(asp, strings.SplitN(ctype, "/", 2))
   144  	}
   145  	for _, clause := range ParseAccept(header) {
   146  		for i, ctsp := range asp {
   147  			if clause.Type == ctsp[0] && clause.SubType == ctsp[1] {
   148  				content_type = alternatives[i]
   149  				return
   150  			}
   151  			if clause.Type == ctsp[0] && clause.SubType == "*" {
   152  				content_type = alternatives[i]
   153  				return
   154  			}
   155  			if clause.Type == "*" && clause.SubType == "*" {
   156  				content_type = alternatives[i]
   157  				return
   158  			}
   159  		}
   160  	}
   161  	return
   162  }