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Normalize allowed request headers and store them in a sorted set (fixes
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,113 @@ | ||
| // adapted from github.com/jub0bs/cors | ||
| package internal | ||
|
|
||
| import ( | ||
| "sort" | ||
| "strings" | ||
| ) | ||
|
|
||
| // A SortedSet represents a mathematical set of strings sorted in | ||
| // lexicographical order. | ||
| // Each element has a unique position ranging from 0 (inclusive) | ||
| // to the set's cardinality (exclusive). | ||
| // The zero value represents an empty set. | ||
| type SortedSet struct { | ||
| m map[string]int | ||
| maxLen int | ||
| } | ||
|
|
||
| // NewSortedSet returns a SortedSet that contains all of elems, | ||
| // but no other elements. | ||
| func NewSortedSet(elems ...string) SortedSet { | ||
| sort.Strings(elems) | ||
| m := make(map[string]int) | ||
| var maxLen int | ||
| i := 0 | ||
| for _, s := range elems { | ||
| if _, exists := m[s]; exists { | ||
| continue | ||
| } | ||
| m[s] = i | ||
| i++ | ||
| maxLen = max(maxLen, len(s)) | ||
| } | ||
| return SortedSet{ | ||
| m: m, | ||
| maxLen: maxLen, | ||
| } | ||
| } | ||
|
|
||
| // Size returns the cardinality of set. | ||
| func (set SortedSet) Size() int { | ||
| return len(set.m) | ||
| } | ||
|
|
||
| // String sorts joins the elements of set (in lexicographical order) | ||
| // with a comma and returns the resulting string. | ||
| func (set SortedSet) String() string { | ||
| elems := make([]string, len(set.m)) | ||
| for elem, i := range set.m { | ||
| elems[i] = elem // safe indexing, by construction of SortedSet | ||
| } | ||
| return strings.Join(elems, ",") | ||
| } | ||
|
|
||
| // Subsumes reports whether csv is a sequence of comma-separated names that are | ||
| // - all elements of set, | ||
| // - sorted in lexicographically order, | ||
| // - unique. | ||
| func (set SortedSet) Subsumes(csv string) bool { | ||
| if csv == "" { | ||
| return true | ||
| } | ||
| posOfLastNameSeen := -1 | ||
| chunkSize := set.maxLen + 1 // (to accommodate for at least one comma) | ||
| for { | ||
| // As a defense against maliciously long names in csv, | ||
| // we only process at most chunkSize bytes per iteration. | ||
| end := min(len(csv), chunkSize) | ||
| comma := strings.IndexByte(csv[:end], ',') | ||
| var name string | ||
| if comma == -1 { | ||
| name = csv | ||
| } else { | ||
| name = csv[:comma] | ||
| } | ||
| pos, found := set.m[name] | ||
| if !found { | ||
| return false | ||
| } | ||
| // The names in csv are expected to be sorted in lexicographical order | ||
| // and appear at most once in csv. | ||
| // Therefore, the positions (in set) of the names that | ||
| // appear in csv should form a strictly increasing sequence. | ||
| // If that's not actually the case, bail out. | ||
| if pos <= posOfLastNameSeen { | ||
| return false | ||
| } | ||
| posOfLastNameSeen = pos | ||
| if comma < 0 { // We've now processed all the names in csv. | ||
| break | ||
| } | ||
| csv = csv[comma+1:] | ||
| } | ||
| return true | ||
| } | ||
|
|
||
| // TODO: when updating go directive to 1.21 or later, | ||
| // use min builtin instead. | ||
| func min(a, b int) int { | ||
| if a < b { | ||
| return a | ||
| } | ||
| return b | ||
| } | ||
|
|
||
| // TODO: when updating go directive to 1.21 or later, | ||
| // use max builtin instead. | ||
| func max(a, b int) int { | ||
| if a > b { | ||
| return a | ||
| } | ||
| return b | ||
| } |
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