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