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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// 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 "base/logging.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 {
namespace 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;
size_t GetRegistryLengthImpl(base::StringPiece 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::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_len = host.length();
if (host[host_check_len - 1] == '.') {
DCHECK(host_check_len > 0); // If this weren't true, the host would be ".",
// and we'd have already returned above.
if (host[host_check_len - 1] == '.')
return 0; // Multiple trailing dots.
// Walk up the domain tree, most specific to least specific,
// looking for matches at each level.
size_t prev_start = std::string::npos;
size_t curr_start = host_check_begin;
size_t next_dot = host.find('.', curr_start);
if (next_dot >= host_check_len) // Catches std::string::npos as well.
return 0; // This can't have a registry + domain.
while (1) {
const char* domain_str = + curr_start;
size_t domain_length = host_check_len - curr_start;
int type = LookupStringInFixedSet(g_graph, g_graph_length, domain_str,
bool do_check = type != kDafsaNotFound &&
(!(type & kDafsaPrivateRule) ||
// If the apparent match is a private registry and we're not including
// those, it can't be an actual match.
if (do_check) {
// Exception rules override wildcard rules when the domain is an exact
// match, but wildcards take precedence when there's a subdomain.
if (type & kDafsaWildcardRule && (prev_start != std::string::npos)) {
// If prev_start == host_check_begin, then the host is the registry
// itself, so return 0.
return (prev_start == host_check_begin) ? 0
: (host.length() - prev_start);
if (type & kDafsaExceptionRule) {
if (next_dot == std::string::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.
NOTREACHED() << "Invalid exception rule";
return 0;
return host.length() - next_dot - 1;
// If curr_start == host_check_begin, then the host is the registry
// itself, so return 0.
return (curr_start == host_check_begin) ? 0
: (host.length() - curr_start);
if (next_dot >= host_check_len) // Catches std::string::npos as well.
prev_start = curr_start;
curr_start = next_dot + 1;
next_dot = host.find('.', curr_start);
// No rule found in the registry. curr_start now points to the first
// character of the last subcomponent of the host, so if we allow unknown
// registries, return the length of this subcomponent.
return unknown_filter == INCLUDE_UNKNOWN_REGISTRIES ?
(host.length() - curr_start) : 0;
base::StringPiece GetDomainAndRegistryImpl(
base::StringPiece 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 base::StringPiece(); // No registry.
// The "2" in this next line is 1 for the dot, plus a 1-char minimum preceding
// subcomponent length.
DCHECK(host.length() >= 2);
if (registry_length > (host.length() - 2)) {
"Host does not have at least one subcomponent before registry!";
return base::StringPiece();
// 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.
base::StringPiece GetDomainAndRegistryAsStringPiece(
base::StringPiece host,
PrivateRegistryFilter filter) {
if (host.empty() || url::HostIsIPAddress(host))
return base::StringPiece();
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(base::StringPiece str, url::CanonOutput* output) {
output->Append(, static_cast<int>(str.length()));
void AppendInvalidString(base::StringPiece16 str, url::CanonOutput* output) {
std::string utf8 = base::UTF16ToUTF8(str);
output->Append(, static_cast<int>(utf8.length()));
// Backend for PermissiveGetHostRegistryLength that handles both UTF-8 and
// UTF-16 input. The template type is the std::string type to use (it makes the
// typedefs easier than using the character type).
template <typename Str>
size_t DoPermissiveGetHostRegistryLength(base::BasicStringPiece<Str> 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 = static_cast<size_t>(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 = static_cast<size_t>(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.
base::StringPiece 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(base::StringPiece host1,
base::StringPiece 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.
const base::StringPiece& domain1 =
GetDomainAndRegistryAsStringPiece(host1, filter);
return !domain1.empty() &&
(domain1 == GetDomainAndRegistryAsStringPiece(host2, filter));
} // namespace
std::string GetDomainAndRegistry(const GURL& gurl,
PrivateRegistryFilter filter) {
return GetDomainAndRegistryAsStringPiece(gurl.host_piece(), filter)
std::string GetDomainAndRegistry(base::StringPiece 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 GetDomainAndRegistryImpl(canon_host, filter).as_string();
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 base::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(base::StringPiece 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(base::StringPiece 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(base::StringPiece host,
UnknownRegistryFilter unknown_filter,
PrivateRegistryFilter private_filter) {
return DoPermissiveGetHostRegistryLength<std::string>(host, unknown_filter,
size_t PermissiveGetHostRegistryLength(base::StringPiece16 host,
UnknownRegistryFilter unknown_filter,
PrivateRegistryFilter private_filter) {
return DoPermissiveGetHostRegistryLength<base::string16>(host, unknown_filter,
void SetFindDomainGraph() {
g_graph = kDafsa;
g_graph_length = sizeof(kDafsa);
void SetFindDomainGraph(const unsigned char* domains, size_t length) {
CHECK_NE(length, 0u);
g_graph = domains;
g_graph_length = length;
} // namespace registry_controlled_domains
} // namespace net