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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// NB: Modelled after Mozilla's code (originally written by Pamela Greene,
// later modified by others), but almost entirely rewritten for Chrome.
// (netwerk/dns/src/nsEffectiveTLDService.cpp)
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
* The Original Code is Mozilla Effective-TLD Service
* The Initial Developer of the Original Code is
* Google Inc.
* Portions created by the Initial Developer are Copyright (C) 2006
* the Initial Developer. All Rights Reserved.
* Contributor(s):
* Pamela Greene <> (original author)
* Daniel Witte <>
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
* ***** END LICENSE BLOCK ***** */
#include "net/base/registry_controlled_domains/registry_controlled_domain.h"
#include <ostream>
#include <string_view>
#include "base/check_op.h"
#include "base/notreached.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "net/base/lookup_string_in_fixed_set.h"
#include "net/base/net_module.h"
#include "net/base/url_util.h"
#include "url/gurl.h"
#include "url/origin.h"
#include "url/third_party/mozilla/url_parse.h"
#include "url/url_util.h"
namespace net::registry_controlled_domains {
namespace {
#include "net/base/registry_controlled_domains/"
// See for documentation of the generated dafsa byte array.
const unsigned char* g_graph = kDafsa;
size_t g_graph_length = sizeof(kDafsa);
struct MappedHostComponent {
size_t original_begin;
size_t original_end;
size_t canonical_begin;
size_t canonical_end;
// This version assumes we already removed leading dots from host as well as the
// last trailing dot if it had one.
size_t GetRegistryLengthInTrimmedHost(std::string_view host,
UnknownRegistryFilter unknown_filter,
PrivateRegistryFilter private_filter) {
size_t length;
int type = LookupSuffixInReversedSet(
g_graph, g_graph_length, private_filter == INCLUDE_PRIVATE_REGISTRIES,
host, &length);
CHECK_LE(length, host.size());
// No rule found in the registry.
if (type == kDafsaNotFound) {
// If we allow unknown registries, return the length of last subcomponent.
if (unknown_filter == INCLUDE_UNKNOWN_REGISTRIES) {
const size_t last_dot = host.find_last_of('.');
if (last_dot != std::string_view::npos) {
return host.size() - last_dot - 1;
return 0;
// Exception rules override wildcard rules when the domain is an exact
// match, but wildcards take precedence when there's a subdomain.
if (type & kDafsaWildcardRule) {
// If the complete host matches, then the host is the wildcard suffix, so
// return 0.
if (length == host.size())
return 0;
CHECK_LE(length + 2, host.size());
CHECK_EQ('.', host[host.size() - length - 1]);
const size_t preceding_dot =
host.find_last_of('.', host.size() - length - 2);
// If no preceding dot, then the host is the registry itself, so return 0.
if (preceding_dot == std::string_view::npos) {
return 0;
// Return suffix size plus size of subdomain.
return host.size() - preceding_dot - 1;
if (type & kDafsaExceptionRule) {
size_t first_dot = host.find_first_of('.', host.size() - length);
if (first_dot == std::string_view::npos) {
// If we get here, we had an exception rule with no dots (e.g.
// "!foo"). This would only be valid if we had a corresponding
// wildcard rule, which would have to be "*". But we explicitly
// disallow that case, so this kind of rule is invalid.
// TODO( This assumes that all wildcard entries,
// such as *.foo.invalid, also have their parent, foo.invalid, as an entry
// on the PSL, which is why it returns the length of foo.invalid. This
// isn't entirely correct.
NOTREACHED() << "Invalid exception rule";
return 0;
return host.length() - first_dot - 1;
CHECK_NE(type, kDafsaNotFound);
// If a complete match, then the host is the registry itself, so return 0.
if (length == host.size())
return 0;
return length;
size_t GetRegistryLengthImpl(std::string_view host,
UnknownRegistryFilter unknown_filter,
PrivateRegistryFilter private_filter) {
if (host.empty())
return std::string::npos;
// Skip leading dots.
const size_t host_check_begin = host.find_first_not_of('.');
if (host_check_begin == std::string_view::npos) {
return 0; // Host is only dots.
// A single trailing dot isn't relevant in this determination, but does need
// to be included in the final returned length.
size_t host_check_end = host.size();
if (host.back() == '.')
size_t length = GetRegistryLengthInTrimmedHost(
host.substr(host_check_begin, host_check_end - host_check_begin),
unknown_filter, private_filter);
if (length == 0)
return 0;
return length + host.size() - host_check_end;
std::string_view GetDomainAndRegistryImpl(
std::string_view host,
PrivateRegistryFilter private_filter) {
// Find the length of the registry for this host.
const size_t registry_length =
GetRegistryLengthImpl(host, INCLUDE_UNKNOWN_REGISTRIES, private_filter);
if ((registry_length == std::string::npos) || (registry_length == 0))
return std::string_view(); // No registry.
// The "2" in this next line is 1 for the dot, plus a 1-char minimum preceding
// subcomponent length.
CHECK_GE(host.length(), 2u);
CHECK_LE(registry_length, host.length() - 2)
<< "Host does not have at least one subcomponent before registry!";
// Move past the dot preceding the registry, and search for the next previous
// dot. Return the host from after that dot, or the whole host when there is
// no dot.
const size_t dot = host.rfind('.', host.length() - registry_length - 2);
if (dot == std::string::npos)
return host;
return host.substr(dot + 1);
// Same as GetDomainAndRegistry, but returns the domain and registry as a
// StringPiece that references the underlying string of the passed-in |gurl|.
// TODO(pkalinnikov): Eliminate this helper by exposing StringPiece as the
// interface type for all the APIs.
std::string_view GetDomainAndRegistryAsStringPiece(
std::string_view host,
PrivateRegistryFilter filter) {
if (host.empty() || url::HostIsIPAddress(host))
return std::string_view();
return GetDomainAndRegistryImpl(host, filter);
// These two functions append the given string as-is to the given output,
// converting to UTF-8 if necessary.
void AppendInvalidString(std::string_view str, url::CanonOutput* output) {
void AppendInvalidString(std::u16string_view str, url::CanonOutput* output) {
// Backend for PermissiveGetHostRegistryLength that handles both UTF-8 and
// UTF-16 input.
template <typename T, typename CharT = typename T::value_type>
size_t DoPermissiveGetHostRegistryLength(T host,
UnknownRegistryFilter unknown_filter,
PrivateRegistryFilter private_filter) {
std::string canonical_host; // Do not modify outside of canon_output.
url::StdStringCanonOutput canon_output(&canonical_host);
std::vector<MappedHostComponent> components;
for (size_t current = 0; current < host.length(); current++) {
size_t begin = current;
// Advance to next "." or end.
current = host.find('.', begin);
if (current == std::string::npos)
current = host.length();
MappedHostComponent mapping;
mapping.original_begin = begin;
mapping.original_end = current;
mapping.canonical_begin = canon_output.length();
// Try to append the canonicalized version of this component.
int current_len = static_cast<int>(current - begin);
if (!url::CanonicalizeHostSubstring(, url::Component(static_cast<int>(begin), current_len),
&canon_output)) {
// Failed to canonicalize this component; append as-is.
AppendInvalidString(host.substr(begin, current_len), &canon_output);
mapping.canonical_end = canon_output.length();
if (current < host.length())
size_t canonical_rcd_len =
GetRegistryLengthImpl(canonical_host, unknown_filter, private_filter);
if (canonical_rcd_len == 0 || canonical_rcd_len == std::string::npos)
return canonical_rcd_len; // Error or no registry controlled domain.
// Find which host component the result started in.
size_t canonical_rcd_begin = canonical_host.length() - canonical_rcd_len;
for (const auto& mapping : components) {
// In the common case, GetRegistryLengthImpl will identify the beginning
// of a component and we can just return where that component was in the
// original string.
if (canonical_rcd_begin == mapping.canonical_begin)
return host.length() - mapping.original_begin;
if (canonical_rcd_begin >= mapping.canonical_end)
// The registry controlled domain begin was identified as being in the
// middle of this dot-separated domain component in the non-canonical
// input. This indicates some form of escaped dot, or a non-ASCII
// character that was canonicalized to a dot.
// Brute-force search from the end by repeatedly canonicalizing longer
// substrings until we get a match for the canonicalized version. This
// can't be done with binary search because canonicalization might increase
// or decrease the length of the produced string depending on where it's
// split. This depends on the canonicalization process not changing the
// order of the characters. Punycode can change the order of characters,
// but it doesn't work across dots so this is safe.
// Expected canonical registry controlled domain.
std::string_view canonical_rcd(&canonical_host[canonical_rcd_begin],
for (int current_try = static_cast<int>(mapping.original_end) - 1;
current_try >= static_cast<int>(mapping.original_begin);
current_try--) {
std::string try_string;
url::StdStringCanonOutput try_output(&try_string);
if (!url::CanonicalizeHostSubstring(,
static_cast<int>(mapping.original_end) - current_try),
continue; // Invalid substring, skip.
if (try_string == canonical_rcd)
return host.length() - current_try;
return canonical_rcd_len;
bool SameDomainOrHost(std::string_view host1,
std::string_view host2,
PrivateRegistryFilter filter) {
// Quickly reject cases where either host is empty.
if (host1.empty() || host2.empty())
return false;
// Check for exact host matches, which is faster than looking up the domain
// and registry.
if (host1 == host2)
return true;
// Check for a domain and registry match.
std::string_view domain1 = GetDomainAndRegistryAsStringPiece(host1, filter);
return !domain1.empty() &&
(domain1 == GetDomainAndRegistryAsStringPiece(host2, filter));
} // namespace
std::string GetDomainAndRegistry(const GURL& gurl,
PrivateRegistryFilter filter) {
return std::string(
GetDomainAndRegistryAsStringPiece(gurl.host_piece(), filter));
std::string GetDomainAndRegistry(const url::Origin& origin,
PrivateRegistryFilter filter) {
return std::string(GetDomainAndRegistryAsStringPiece(, filter));
std::string GetDomainAndRegistry(std::string_view host,
PrivateRegistryFilter filter) {
url::CanonHostInfo host_info;
const std::string canon_host(CanonicalizeHost(host, &host_info));
if (canon_host.empty() || host_info.IsIPAddress())
return std::string();
return std::string(GetDomainAndRegistryImpl(canon_host, filter));
bool SameDomainOrHost(
const GURL& gurl1,
const GURL& gurl2,
PrivateRegistryFilter filter) {
return SameDomainOrHost(gurl1.host_piece(), gurl2.host_piece(), filter);
bool SameDomainOrHost(const url::Origin& origin1,
const url::Origin& origin2,
PrivateRegistryFilter filter) {
return SameDomainOrHost(,, filter);
bool SameDomainOrHost(const url::Origin& origin1,
const std::optional<url::Origin>& origin2,
PrivateRegistryFilter filter) {
return origin2.has_value() &&
SameDomainOrHost(origin1, origin2.value(), filter);
bool SameDomainOrHost(const GURL& gurl,
const url::Origin& origin,
PrivateRegistryFilter filter) {
return SameDomainOrHost(gurl.host_piece(),, filter);
size_t GetRegistryLength(
const GURL& gurl,
UnknownRegistryFilter unknown_filter,
PrivateRegistryFilter private_filter) {
return GetRegistryLengthImpl(gurl.host_piece(), unknown_filter,
bool HostHasRegistryControlledDomain(std::string_view host,
UnknownRegistryFilter unknown_filter,
PrivateRegistryFilter private_filter) {
url::CanonHostInfo host_info;
const std::string canon_host(CanonicalizeHost(host, &host_info));
size_t rcd_length;
switch ( {
case url::CanonHostInfo::IPV4:
case url::CanonHostInfo::IPV6:
// IP addresses don't have R.C.D.'s.
return false;
case url::CanonHostInfo::BROKEN:
// Host is not canonicalizable. Fall back to the slower "permissive"
// version.
rcd_length =
PermissiveGetHostRegistryLength(host, unknown_filter, private_filter);
case url::CanonHostInfo::NEUTRAL:
rcd_length =
GetRegistryLengthImpl(canon_host, unknown_filter, private_filter);
return false;
return (rcd_length != 0) && (rcd_length != std::string::npos);
size_t GetCanonicalHostRegistryLength(std::string_view canon_host,
UnknownRegistryFilter unknown_filter,
PrivateRegistryFilter private_filter) {
#ifndef NDEBUG
// Ensure passed-in host name is canonical.
url::CanonHostInfo host_info;
DCHECK_EQ(net::CanonicalizeHost(canon_host, &host_info), canon_host);
return GetRegistryLengthImpl(canon_host, unknown_filter, private_filter);
size_t PermissiveGetHostRegistryLength(std::string_view host,
UnknownRegistryFilter unknown_filter,
PrivateRegistryFilter private_filter) {
return DoPermissiveGetHostRegistryLength(host, unknown_filter,
size_t PermissiveGetHostRegistryLength(std::u16string_view host,
UnknownRegistryFilter unknown_filter,
PrivateRegistryFilter private_filter) {
return DoPermissiveGetHostRegistryLength(host, unknown_filter,
void ResetFindDomainGraphForTesting() {
g_graph = kDafsa;
g_graph_length = sizeof(kDafsa);
void SetFindDomainGraphForTesting(const unsigned char* domains, size_t length) {
CHECK_NE(length, 0u);
g_graph = domains;
g_graph_length = length;
} // namespace net::registry_controlled_domains