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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/dns/dns_names_util.h"
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <string>
#include <vector>
#include "base/big_endian.h"
#include "base/check.h"
#include "base/containers/span.h"
#include "base/strings/string_piece.h"
#include "net/base/ip_address.h"
#include "net/base/url_util.h"
#include "net/dns/public/dns_protocol.h"
#include "third_party/abseil-cpp/absl/types/optional.h"
#include "url/third_party/mozilla/url_parse.h"
#include "url/url_canon.h"
#include "url/url_canon_stdstring.h"
namespace net::dns_names_util {
bool IsValidDnsName(base::StringPiece dotted_form_name) {
return DottedNameToNetwork(dotted_form_name,
/*require_valid_internet_hostname=*/false)
.has_value();
}
bool IsValidDnsRecordName(base::StringPiece dotted_form_name) {
IPAddress ip_address;
return IsValidDnsName(dotted_form_name) &&
!HostStringIsLocalhost(dotted_form_name) &&
!ip_address.AssignFromIPLiteral(dotted_form_name) &&
!ParseURLHostnameToAddress(dotted_form_name, &ip_address);
}
// Based on DJB's public domain code.
absl::optional<std::vector<uint8_t>> DottedNameToNetwork(
base::StringPiece dotted_form_name,
bool require_valid_internet_hostname) {
// Use full IsCanonicalizedHostCompliant() validation if not
// `is_unrestricted`. All subsequent validity checks should not apply unless
// `is_unrestricted` because IsCanonicalizedHostCompliant() is expected to be
// more strict than any validation here.
if (require_valid_internet_hostname &&
!IsCanonicalizedHostCompliant(dotted_form_name))
return absl::nullopt;
const char* buf = dotted_form_name.data();
size_t n = dotted_form_name.size();
uint8_t label[dns_protocol::kMaxLabelLength];
size_t labellen = 0; /* <= sizeof label */
std::vector<uint8_t> name(dns_protocol::kMaxNameLength, 0);
size_t namelen = 0; /* <= sizeof name */
char ch;
for (;;) {
if (!n)
break;
ch = *buf++;
--n;
if (ch == '.') {
// Don't allow empty labels per http://crbug.com/456391.
if (!labellen) {
DCHECK(!require_valid_internet_hostname);
return absl::nullopt;
}
if (namelen + labellen + 1 > name.size()) {
DCHECK(!require_valid_internet_hostname);
return absl::nullopt;
}
name[namelen++] = static_cast<uint8_t>(labellen);
memcpy(name.data() + namelen, label, labellen);
namelen += labellen;
labellen = 0;
continue;
}
if (labellen >= sizeof(label)) {
DCHECK(!require_valid_internet_hostname);
return absl::nullopt;
}
label[labellen++] = ch;
}
// Allow empty label at end of name to disable suffix search.
if (labellen) {
if (namelen + labellen + 1 > name.size()) {
DCHECK(!require_valid_internet_hostname);
return absl::nullopt;
}
name[namelen++] = static_cast<uint8_t>(labellen);
memcpy(name.data() + namelen, label, labellen);
namelen += labellen;
labellen = 0;
}
if (namelen + 1 > name.size()) {
DCHECK(!require_valid_internet_hostname);
return absl::nullopt;
}
if (namelen == 0) { // Empty names e.g. "", "." are not valid.
DCHECK(!require_valid_internet_hostname);
return absl::nullopt;
}
name[namelen++] = 0; // This is the root label (of length 0).
name.resize(namelen);
return name;
}
absl::optional<std::string> NetworkToDottedName(
base::span<const uint8_t> dns_network_wire_name,
bool require_complete) {
base::BigEndianReader reader(dns_network_wire_name.data(),
dns_network_wire_name.size());
return NetworkToDottedName(reader, require_complete);
}
absl::optional<std::string> NetworkToDottedName(
base::StringPiece dns_network_wire_name,
bool require_complete) {
auto reader = base::BigEndianReader::FromStringPiece(dns_network_wire_name);
return NetworkToDottedName(reader, require_complete);
}
absl::optional<std::string> NetworkToDottedName(base::BigEndianReader& reader,
bool require_complete) {
std::string ret;
size_t octets_read = 0;
while (reader.remaining() > 0) {
// DNS name compression not allowed because it does not make sense without
// the context of a full DNS message.
if ((*reader.ptr() & dns_protocol::kLabelMask) ==
dns_protocol::kLabelPointer)
return absl::nullopt;
base::StringPiece label;
if (!reader.ReadU8LengthPrefixed(&label))
return absl::nullopt;
// Final zero-length label not included in size enforcement.
if (label.size() != 0)
octets_read += label.size() + 1;
if (label.size() > dns_protocol::kMaxLabelLength)
return absl::nullopt;
if (octets_read > dns_protocol::kMaxNameLength)
return absl::nullopt;
if (label.size() == 0)
return ret;
if (!ret.empty())
ret.append(".");
ret.append(label);
}
if (require_complete)
return absl::nullopt;
// If terminating zero-length label was not included in the input, no need to
// recheck against max name length because terminating zero-length label does
// not count against the limit.
return ret;
}
std::string UrlCanonicalizeNameIfAble(base::StringPiece name) {
std::string canonicalized;
url::StdStringCanonOutput output(&canonicalized);
url::CanonHostInfo host_info;
url::CanonicalizeHostVerbose(name.data(), url::Component(0, name.size()),
&output, &host_info);
if (host_info.family == url::CanonHostInfo::Family::BROKEN) {
return std::string(name);
}
output.Complete();
return canonicalized;
}
} // namespace net::dns_names_util
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