182 lines
6 KiB
Go
182 lines
6 KiB
Go
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// Copyright 2012 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:generate go run gen.go
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// Package publicsuffix provides a public suffix list based on data from
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// https://publicsuffix.org/
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//
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// A public suffix is one under which Internet users can directly register
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// names. It is related to, but different from, a TLD (top level domain).
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//
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// "com" is a TLD (top level domain). Top level means it has no dots.
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//
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// "com" is also a public suffix. Amazon and Google have registered different
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// siblings under that domain: "amazon.com" and "google.com".
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//
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// "au" is another TLD, again because it has no dots. But it's not "amazon.au".
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// Instead, it's "amazon.com.au".
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//
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// "com.au" isn't an actual TLD, because it's not at the top level (it has
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// dots). But it is an eTLD (effective TLD), because that's the branching point
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// for domain name registrars.
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//
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// Another name for "an eTLD" is "a public suffix". Often, what's more of
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// interest is the eTLD+1, or one more label than the public suffix. For
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// example, browsers partition read/write access to HTTP cookies according to
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// the eTLD+1. Web pages served from "amazon.com.au" can't read cookies from
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// "google.com.au", but web pages served from "maps.google.com" can share
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// cookies from "www.google.com", so you don't have to sign into Google Maps
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// separately from signing into Google Web Search. Note that all four of those
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// domains have 3 labels and 2 dots. The first two domains are each an eTLD+1,
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// the last two are not (but share the same eTLD+1: "google.com").
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//
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// All of these domains have the same eTLD+1:
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// - "www.books.amazon.co.uk"
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// - "books.amazon.co.uk"
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// - "amazon.co.uk"
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// Specifically, the eTLD+1 is "amazon.co.uk", because the eTLD is "co.uk".
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//
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// There is no closed form algorithm to calculate the eTLD of a domain.
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// Instead, the calculation is data driven. This package provides a
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// pre-compiled snapshot of Mozilla's PSL (Public Suffix List) data at
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// https://publicsuffix.org/
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package publicsuffix // import "golang.org/x/net/publicsuffix"
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// TODO: specify case sensitivity and leading/trailing dot behavior for
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// func PublicSuffix and func EffectiveTLDPlusOne.
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import (
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"fmt"
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"net/http/cookiejar"
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"strings"
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)
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// List implements the cookiejar.PublicSuffixList interface by calling the
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// PublicSuffix function.
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var List cookiejar.PublicSuffixList = list{}
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type list struct{}
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func (list) PublicSuffix(domain string) string {
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ps, _ := PublicSuffix(domain)
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return ps
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}
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func (list) String() string {
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return version
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}
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// PublicSuffix returns the public suffix of the domain using a copy of the
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// publicsuffix.org database compiled into the library.
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//
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// icann is whether the public suffix is managed by the Internet Corporation
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// for Assigned Names and Numbers. If not, the public suffix is either a
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// privately managed domain (and in practice, not a top level domain) or an
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// unmanaged top level domain (and not explicitly mentioned in the
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// publicsuffix.org list). For example, "foo.org" and "foo.co.uk" are ICANN
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// domains, "foo.dyndns.org" and "foo.blogspot.co.uk" are private domains and
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// "cromulent" is an unmanaged top level domain.
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//
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// Use cases for distinguishing ICANN domains like "foo.com" from private
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// domains like "foo.appspot.com" can be found at
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// https://wiki.mozilla.org/Public_Suffix_List/Use_Cases
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func PublicSuffix(domain string) (publicSuffix string, icann bool) {
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lo, hi := uint32(0), uint32(numTLD)
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s, suffix, icannNode, wildcard := domain, len(domain), false, false
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loop:
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for {
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dot := strings.LastIndex(s, ".")
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if wildcard {
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icann = icannNode
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suffix = 1 + dot
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}
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if lo == hi {
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break
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}
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f := find(s[1+dot:], lo, hi)
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if f == notFound {
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break
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}
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u := nodes[f] >> (nodesBitsTextOffset + nodesBitsTextLength)
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icannNode = u&(1<<nodesBitsICANN-1) != 0
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u >>= nodesBitsICANN
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u = children[u&(1<<nodesBitsChildren-1)]
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lo = u & (1<<childrenBitsLo - 1)
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u >>= childrenBitsLo
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hi = u & (1<<childrenBitsHi - 1)
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u >>= childrenBitsHi
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switch u & (1<<childrenBitsNodeType - 1) {
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case nodeTypeNormal:
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suffix = 1 + dot
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case nodeTypeException:
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suffix = 1 + len(s)
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break loop
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}
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u >>= childrenBitsNodeType
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wildcard = u&(1<<childrenBitsWildcard-1) != 0
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if !wildcard {
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icann = icannNode
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}
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if dot == -1 {
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break
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}
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s = s[:dot]
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}
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if suffix == len(domain) {
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// If no rules match, the prevailing rule is "*".
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return domain[1+strings.LastIndex(domain, "."):], icann
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}
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return domain[suffix:], icann
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}
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const notFound uint32 = 1<<32 - 1
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// find returns the index of the node in the range [lo, hi) whose label equals
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// label, or notFound if there is no such node. The range is assumed to be in
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// strictly increasing node label order.
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func find(label string, lo, hi uint32) uint32 {
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for lo < hi {
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mid := lo + (hi-lo)/2
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s := nodeLabel(mid)
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if s < label {
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lo = mid + 1
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} else if s == label {
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return mid
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} else {
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hi = mid
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}
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}
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return notFound
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}
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// nodeLabel returns the label for the i'th node.
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func nodeLabel(i uint32) string {
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x := nodes[i]
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length := x & (1<<nodesBitsTextLength - 1)
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x >>= nodesBitsTextLength
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offset := x & (1<<nodesBitsTextOffset - 1)
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return text[offset : offset+length]
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}
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// EffectiveTLDPlusOne returns the effective top level domain plus one more
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// label. For example, the eTLD+1 for "foo.bar.golang.org" is "golang.org".
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func EffectiveTLDPlusOne(domain string) (string, error) {
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if strings.HasPrefix(domain, ".") || strings.HasSuffix(domain, ".") || strings.Contains(domain, "..") {
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return "", fmt.Errorf("publicsuffix: empty label in domain %q", domain)
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}
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suffix, _ := PublicSuffix(domain)
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if len(domain) <= len(suffix) {
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return "", fmt.Errorf("publicsuffix: cannot derive eTLD+1 for domain %q", domain)
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}
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i := len(domain) - len(suffix) - 1
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if domain[i] != '.' {
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return "", fmt.Errorf("publicsuffix: invalid public suffix %q for domain %q", suffix, domain)
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}
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return domain[1+strings.LastIndex(domain[:i], "."):], nil
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}
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