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// Copyright 2019 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.
#include "discovery/dnssd/public/dns_sd_instance_record.h"
#include "absl/strings/ascii.h"
#include "platform/api/logging.h"
namespace openscreen {
namespace discovery {
namespace {
bool IsValidUtf8(absl::string_view string) {
for (size_t i = 0; i < string.size(); i++) {
if (string[i] >> 5 == 0x06) { // 110xxxxx 10xxxxxx
if (i + 1 >= string.size() || string[++i] >> 6 != 0x02) {
return false;
}
} else if (string[i] >> 4 == 0x0E) { // 1110xxxx 10xxxxxx 10xxxxxx
if (i + 2 >= string.size() || string[++i] >> 6 != 0x02 ||
string[++i] >> 6 != 0x02) {
return false;
}
} else if (string[i] >> 3 == 0x1E) { // 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
if (i + 3 >= string.size() || string[++i] >> 6 != 0x02 ||
string[++i] >> 6 != 0x02 || string[++i] >> 6 != 0x02) {
return false;
}
} else if ((string[i] & 0x80) != 0x0) { // 0xxxxxxx
return false;
}
}
return true;
}
bool HasControlCharacters(absl::string_view string) {
for (auto ch : string) {
if ((ch >= 0x0 && ch <= 0x1F /* Ascii control characters */) ||
ch == 0x7F /* DEL character */) {
return true;
}
}
return false;
}
} // namespace
DnsSdInstanceRecord::DnsSdInstanceRecord(std::string instance_id,
std::string service_id,
std::string domain_id,
IPEndpoint endpoint,
DnsSdTxtRecord txt)
: DnsSdInstanceRecord(std::move(instance_id),
std::move(service_id),
std::move(domain_id),
std::move(txt)) {
if (endpoint.address.IsV4()) {
address_v4_ = std::move(endpoint);
} else if (endpoint.address.IsV6()) {
address_v6_ = std::move(endpoint);
} else {
OSP_NOTREACHED();
}
}
DnsSdInstanceRecord::DnsSdInstanceRecord(std::string instance_id,
std::string service_id,
std::string domain_id,
IPEndpoint ipv4_endpoint,
IPEndpoint ipv6_endpoint,
DnsSdTxtRecord txt)
: DnsSdInstanceRecord(std::move(instance_id),
std::move(service_id),
std::move(domain_id),
std::move(txt)) {
OSP_CHECK(ipv4_endpoint.address.IsV4());
OSP_CHECK(ipv6_endpoint.address.IsV6());
address_v4_ = std::move(ipv4_endpoint);
address_v6_ = std::move(ipv6_endpoint);
}
DnsSdInstanceRecord::DnsSdInstanceRecord(std::string instance_id,
std::string service_id,
std::string domain_id,
DnsSdTxtRecord txt)
: instance_id_(std::move(instance_id)),
service_id_(std::move(service_id)),
domain_id_(std::move(domain_id)),
txt_(std::move(txt)) {
OSP_DCHECK(IsInstanceValid(instance_id_));
OSP_DCHECK(IsServiceValid(service_id_));
OSP_DCHECK(IsDomainValid(domain_id_));
}
bool DnsSdInstanceRecord::operator==(const DnsSdInstanceRecord& other) const {
return instance_id_ == other.instance_id_ &&
service_id_ == other.service_id_ && domain_id_ == other.domain_id_ &&
address_v4_ == other.address_v4_ && address_v6_ == other.address_v6_ &&
txt_ == other.txt_;
}
uint16_t DnsSdInstanceRecord::port() const {
if (address_v4_.has_value()) {
return address_v4_.value().port;
} else if (address_v6_.has_value()) {
return address_v6_.value().port;
} else {
OSP_NOTREACHED();
return 0;
}
}
// static
bool IsInstanceValid(absl::string_view instance) {
// According to RFC6763, Instance names must:
// - Be encoded in Net-Unicode (which required UTF-8 formatting).
// - NOT contain ASCII control characters
// - Be no longer than 63 octets.
return instance.size() <= 63 && !HasControlCharacters(instance) &&
IsValidUtf8(instance);
}
// static
bool IsServiceValid(absl::string_view service) {
// According to RFC6763, the service name "consists of a pair of DNS labels".
// "The first label of the pair is an underscore character followed by the
// Service Name" and "The second label is either '_tcp' [...] or '_udp'".
// According to RFC6335 Section 5.1, the Service Name section must:
// Contain from 1 to 15 characters.
// - Only contain A-Z, a-Z, 0-9, and the hyphen character.
// - Contain at least one letter.
// - NOT begin or end with a hyphen.
// - NOT contain two adjacent hyphens.
if (service.size() > 21 || service.size() < 7) { // Service name size + 6.
return false;
}
const absl::string_view protocol = service.substr(service.size() - 5);
if (protocol != "._udp" && protocol != "._tcp") {
return false;
}
if (service[0] != '_' || service[1] == '-' ||
service[service.size() - 6] == '-') {
return false;
}
bool last_char_hyphen = false;
bool seen_letter = false;
for (size_t i = 1; i < service.size() - 5; i++) {
if (service[i] == '-') {
if (last_char_hyphen) {
return false;
}
last_char_hyphen = true;
} else if (absl::ascii_isalpha(service[i])) {
seen_letter = true;
} else if (!absl::ascii_isdigit(service[i])) {
return false;
}
}
return seen_letter;
}
// static
bool IsDomainValid(absl::string_view domain) {
// As RFC6763 Section 4.1.3 provides no validation requirements for the domain
// section, the following validations are used:
// - All labels must be no longer than 63 characters
// - Total length must be no more than 256 characters
// - Must be encoded using valid UTF8
// - Must not include any ASCII control characters
if (domain.size() > 255) {
return false;
}
size_t label_start = 0;
for (size_t next_dot = domain.find('.'); next_dot != std::string::npos;
next_dot = domain.find('.', label_start)) {
if (next_dot - label_start > 63) {
return false;
}
label_start = next_dot + 1;
}
return !HasControlCharacters(domain) && IsValidUtf8(domain);
}
} // namespace discovery
} // namespace openscreen
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