p2p/base/mdns_message.cc - src.git - Git at Google

 /*
  *  Copyright 2018 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */

 #include "p2p/base/mdns_message.h"
 #include "rtc_base/logging.h"
 #include "rtc_base/nethelpers.h"
 #include "rtc_base/stringencode.h"

 namespace webrtc {

 namespace {
 // RFC 1035, Section 4.1.1.
 //
 // QR bit.
 constexpr uint16_t kMDnsFlagMaskQueryOrResponse = 0x8000;
 // AA bit.
 constexpr uint16_t kMDnsFlagMaskAuthoritative = 0x0400;
 // RFC 1035, Section 4.1.2, QCLASS and RFC 6762, Section 18.12, repurposing of
 // top bit of QCLASS as the unicast response bit.
 constexpr uint16_t kMDnsQClassMaskUnicastResponse = 0x8000;
 constexpr size_t kMDnsHeaderSizeBytes = 12;

 bool ReadDomainName(MessageBufferReader* buf, std::string* name) {
   size_t name_start_pos = buf->CurrentOffset();
   uint8_t label_length;
   if (!buf->ReadUInt8(&label_length)) {
     return false;
   }
   // RFC 1035, Section 4.1.4.
   //
   // If the first two bits of the length octet are ones, the name is compressed
   // and the rest six bits with the next octet denotes its position in the
   // message by the offset from the start of the message.
   auto is_pointer = [](uint8_t octet) {
     return (octet & 0x80) && (octet & 0x40);
   };
   while (label_length && !is_pointer(label_length)) {
     // RFC 1035, Section 2.3.1, labels are restricted to 63 octets or less.
     if (label_length > 63) {
       return false;
     }
     std::string label;
     if (!buf->ReadString(&label, label_length)) {
       return false;
     }
     (*name) += label + ".";
     if (!buf->ReadUInt8(&label_length)) {
       return false;
     }
   }
   if (is_pointer(label_length)) {
     uint8_t next_octet;
     if (!buf->ReadUInt8(&next_octet)) {
       return false;
     }
     size_t pos_jump_to = ((label_length & 0x3f) << 8) | next_octet;
     // A legitimate pointer only refers to a prior occurrence of the same name,
     // and we should only move strictly backward to a prior name field after the
     // header.
     if (pos_jump_to >= name_start_pos || pos_jump_to < kMDnsHeaderSizeBytes) {
       return false;
     }
     MessageBufferReader new_buf(buf->MessageData(), buf->MessageLength());
     if (!new_buf.Consume(pos_jump_to)) {
       return false;
     }
     return ReadDomainName(&new_buf, name);
   }
   return true;
 }

 void WriteDomainName(rtc::ByteBufferWriter* buf, const std::string& name) {
   std::vector<std::string> labels;
   rtc::tokenize(name, '.', &labels);
   for (const auto& label : labels) {
     buf->WriteUInt8(label.length());
     buf->WriteString(label);
   }
   buf->WriteUInt8(0);
 }

 }  // namespace

 void MDnsHeader::SetQueryOrResponse(bool is_query) {
   if (is_query) {
     flags &= ~kMDnsFlagMaskQueryOrResponse;
   } else {
     flags |= kMDnsFlagMaskQueryOrResponse;
   }
 }

 void MDnsHeader::SetAuthoritative(bool is_authoritative) {
   if (is_authoritative) {
     flags |= kMDnsFlagMaskAuthoritative;
   } else {
     flags &= ~kMDnsFlagMaskAuthoritative;
   }
 }

 bool MDnsHeader::IsAuthoritative() const {
   return flags & kMDnsFlagMaskAuthoritative;
 }

 bool MDnsHeader::Read(MessageBufferReader* buf) {
   if (!buf->ReadUInt16(&id) || !buf->ReadUInt16(&flags) ||
       !buf->ReadUInt16(&qdcount) || !buf->ReadUInt16(&ancount) ||
       !buf->ReadUInt16(&nscount) || !buf->ReadUInt16(&arcount)) {
     RTC_LOG(LS_ERROR) << "Invalid mDNS header.";
     return false;
   }
   return true;
 }

 void MDnsHeader::Write(rtc::ByteBufferWriter* buf) const {
   buf->WriteUInt16(id);
   buf->WriteUInt16(flags);
   buf->WriteUInt16(qdcount);
   buf->WriteUInt16(ancount);
   buf->WriteUInt16(nscount);
   buf->WriteUInt16(arcount);
 }

 bool MDnsHeader::IsQuery() const {
   return !(flags & kMDnsFlagMaskQueryOrResponse);
 }

 MDnsSectionEntry::MDnsSectionEntry() = default;
 MDnsSectionEntry::~MDnsSectionEntry() = default;
 MDnsSectionEntry::MDnsSectionEntry(const MDnsSectionEntry& other) = default;

 void MDnsSectionEntry::SetType(SectionEntryType type) {
   switch (type) {
     case SectionEntryType::kA:
       type_ = 1;
       return;
     case SectionEntryType::kAAAA:
       type_ = 28;
       return;
     default:
       RTC_NOTREACHED();
   }
 }

 SectionEntryType MDnsSectionEntry::GetType() const {
   switch (type_) {
     case 1:
       return SectionEntryType::kA;
     case 28:
       return SectionEntryType::kAAAA;
     default:
       return SectionEntryType::kUnsupported;
   }
 }

 void MDnsSectionEntry::SetClass(SectionEntryClass cls) {
   switch (cls) {
     case SectionEntryClass::kIN:
       class_ = 1;
       return;
     default:
       RTC_NOTREACHED();
   }
 }

 SectionEntryClass MDnsSectionEntry::GetClass() const {
   switch (class_) {
     case 1:
       return SectionEntryClass::kIN;
     default:
       return SectionEntryClass::kUnsupported;
   }
 }

 MDnsQuestion::MDnsQuestion() = default;
 MDnsQuestion::MDnsQuestion(const MDnsQuestion& other) = default;
 MDnsQuestion::~MDnsQuestion() = default;

 bool MDnsQuestion::Read(MessageBufferReader* buf) {
   if (!ReadDomainName(buf, &name_)) {
     RTC_LOG(LS_ERROR) << "Invalid name.";
     return false;
   }
   if (!buf->ReadUInt16(&type_) || !buf->ReadUInt16(&class_)) {
     RTC_LOG(LS_ERROR) << "Invalid type and class.";
     return false;
   }
   return true;
 }

 bool MDnsQuestion::Write(rtc::ByteBufferWriter* buf) const {
   WriteDomainName(buf, name_);
   buf->WriteUInt16(type_);
   buf->WriteUInt16(class_);
   return true;
 }

 void MDnsQuestion::SetUnicastResponse(bool should_unicast) {
   if (should_unicast) {
     class_ |= kMDnsQClassMaskUnicastResponse;
   } else {
     class_ &= ~kMDnsQClassMaskUnicastResponse;
   }
 }

 bool MDnsQuestion::ShouldUnicastResponse() const {
   return class_ & kMDnsQClassMaskUnicastResponse;
 }

 MDnsResourceRecord::MDnsResourceRecord() = default;
 MDnsResourceRecord::MDnsResourceRecord(const MDnsResourceRecord& other) =
     default;
 MDnsResourceRecord::~MDnsResourceRecord() = default;

 bool MDnsResourceRecord::Read(MessageBufferReader* buf) {
   if (!ReadDomainName(buf, &name_)) {
     return false;
   }
   if (!buf->ReadUInt16(&type_) || !buf->ReadUInt16(&class_) ||
       !buf->ReadUInt32(&ttl_seconds_) || !buf->ReadUInt16(&rdlength_)) {
     return false;
   }

   switch (GetType()) {
     case SectionEntryType::kA:
       return ReadARData(buf);
     case SectionEntryType::kAAAA:
       return ReadQuadARData(buf);
     case SectionEntryType::kUnsupported:
       return false;
     default:
       RTC_NOTREACHED();
   }
   return false;
 }
 bool MDnsResourceRecord::ReadARData(MessageBufferReader* buf) {
   // A RDATA contains a 32-bit IPv4 address.
   return buf->ReadString(&rdata_, 4);
 }

 bool MDnsResourceRecord::ReadQuadARData(MessageBufferReader* buf) {
   // AAAA RDATA contains a 128-bit IPv6 address.
   return buf->ReadString(&rdata_, 16);
 }

 bool MDnsResourceRecord::Write(rtc::ByteBufferWriter* buf) const {
   WriteDomainName(buf, name_);
   buf->WriteUInt16(type_);
   buf->WriteUInt16(class_);
   buf->WriteUInt32(ttl_seconds_);
   buf->WriteUInt16(rdlength_);
   switch (GetType()) {
     case SectionEntryType::kA:
       WriteARData(buf);
       return true;
     case SectionEntryType::kAAAA:
       WriteQuadARData(buf);
       return true;
     case SectionEntryType::kUnsupported:
       return false;
     default:
       RTC_NOTREACHED();
   }
   return true;
 }

 void MDnsResourceRecord::WriteARData(rtc::ByteBufferWriter* buf) const {
   buf->WriteString(rdata_);
 }

 void MDnsResourceRecord::WriteQuadARData(rtc::ByteBufferWriter* buf) const {
   buf->WriteString(rdata_);
 }

 bool MDnsResourceRecord::SetIPAddressInRecordData(
     const rtc::IPAddress& address) {
   int af = address.family();
   if (af != AF_INET && af != AF_INET6) {
     return false;
   }
   char out[16] = {0};
   if (!rtc::inet_pton(af, address.ToString().c_str(), out)) {
     return false;
   }
   rdlength_ = (af == AF_INET) ? 4 : 16;
   rdata_ = std::string(out, rdlength_);
   return true;
 }

 bool MDnsResourceRecord::GetIPAddressFromRecordData(
     rtc::IPAddress* address) const {
   if (GetType() != SectionEntryType::kA &&
       GetType() != SectionEntryType::kAAAA) {
     return false;
   }
   if (rdata_.size() != 4 && rdata_.size() != 16) {
     return false;
   }
   char out[INET6_ADDRSTRLEN] = {0};
   int af = (GetType() == SectionEntryType::kA) ? AF_INET : AF_INET6;
   if (!rtc::inet_ntop(af, rdata_.data(), out, sizeof(out))) {
     return false;
   }
   return rtc::IPFromString(std::string(out), address);
 }

 MDnsMessage::MDnsMessage() = default;
 MDnsMessage::~MDnsMessage() = default;

 bool MDnsMessage::Read(MessageBufferReader* buf) {
   RTC_DCHECK_EQ(0u, buf->CurrentOffset());
   if (!header_.Read(buf)) {
     return false;
   }

   auto read_question = [&buf](std::vector<MDnsQuestion>* section,
                               uint16_t count) {
     section->resize(count);
     for (auto& question : (*section)) {
       if (!question.Read(buf)) {
         return false;
       }
     }
     return true;
   };
   auto read_rr = [&buf](std::vector<MDnsResourceRecord>* section,
                         uint16_t count) {
     section->resize(count);
     for (auto& rr : (*section)) {
       if (!rr.Read(buf)) {
         return false;
       }
     }
     return true;
   };

   if (!read_question(&question_section_, header_.qdcount) ||
       !read_rr(&answer_section_, header_.ancount) ||
       !read_rr(&authority_section_, header_.nscount) ||
       !read_rr(&additional_section_, header_.arcount)) {
     return false;
   }
   return true;
 }

 bool MDnsMessage::Write(rtc::ByteBufferWriter* buf) const {
   header_.Write(buf);

   auto write_rr = [&buf](const std::vector<MDnsResourceRecord>& section) {
     for (auto rr : section) {
       if (!rr.Write(buf)) {
         return false;
       }
     }
     return true;
   };

   for (auto question : question_section_) {
     if (!question.Write(buf)) {
       return false;
     }
   }
   if (!write_rr(answer_section_) || !write_rr(authority_section_) ||
       !write_rr(additional_section_)) {
     return false;
   }

   return true;
 }

 bool MDnsMessage::ShouldUnicastResponse() const {
   bool should_unicast = false;
   for (const auto& question : question_section_) {
     should_unicast |= question.ShouldUnicastResponse();
   }
   return should_unicast;
 }

 void MDnsMessage::AddQuestion(const MDnsQuestion& question) {
   question_section_.push_back(question);
   header_.qdcount = question_section_.size();
 }

 void MDnsMessage::AddAnswerRecord(const MDnsResourceRecord& answer) {
   answer_section_.push_back(answer);
   header_.ancount = answer_section_.size();
 }

 }  // namespace webrtc
	/*
	* Copyright 2018 The WebRTC Project Authors. All rights reserved.
	*
	* Use of this source code is governed by a BSD-style license
	* that can be found in the LICENSE file in the root of the source
	* tree. An additional intellectual property rights grant can be found
	* in the file PATENTS. All contributing project authors may
	* be found in the AUTHORS file in the root of the source tree.
	*/

	#include "p2p/base/mdns_message.h"
	#include "rtc_base/logging.h"
	#include "rtc_base/nethelpers.h"
	#include "rtc_base/stringencode.h"

	namespace webrtc {

	namespace {
	// RFC 1035, Section 4.1.1.
	//
	// QR bit.
	constexpr uint16_t kMDnsFlagMaskQueryOrResponse = 0x8000;
	// AA bit.
	constexpr uint16_t kMDnsFlagMaskAuthoritative = 0x0400;
	// RFC 1035, Section 4.1.2, QCLASS and RFC 6762, Section 18.12, repurposing of
	// top bit of QCLASS as the unicast response bit.
	constexpr uint16_t kMDnsQClassMaskUnicastResponse = 0x8000;
	constexpr size_t kMDnsHeaderSizeBytes = 12;

	bool ReadDomainName(MessageBufferReader* buf, std::string* name) {
	size_t name_start_pos = buf->CurrentOffset();
	uint8_t label_length;
	if (!buf->ReadUInt8(&label_length)) {
	return false;
	}
	// RFC 1035, Section 4.1.4.
	//
	// If the first two bits of the length octet are ones, the name is compressed
	// and the rest six bits with the next octet denotes its position in the
	// message by the offset from the start of the message.
	auto is_pointer = [](uint8_t octet) {
	return (octet & 0x80) && (octet & 0x40);
	};
	while (label_length && !is_pointer(label_length)) {
	// RFC 1035, Section 2.3.1, labels are restricted to 63 octets or less.
	if (label_length > 63) {
	return false;
	}
	std::string label;
	if (!buf->ReadString(&label, label_length)) {
	return false;
	}
	(*name) += label + ".";
	if (!buf->ReadUInt8(&label_length)) {
	return false;
	}
	}
	if (is_pointer(label_length)) {
	uint8_t next_octet;
	if (!buf->ReadUInt8(&next_octet)) {
	return false;
	}
	size_t pos_jump_to = ((label_length & 0x3f) << 8) \| next_octet;
	// A legitimate pointer only refers to a prior occurrence of the same name,
	// and we should only move strictly backward to a prior name field after the
	// header.
	if (pos_jump_to >= name_start_pos \|\| pos_jump_to < kMDnsHeaderSizeBytes) {
	return false;
	}
	MessageBufferReader new_buf(buf->MessageData(), buf->MessageLength());
	if (!new_buf.Consume(pos_jump_to)) {
	return false;
	}
	return ReadDomainName(&new_buf, name);
	}
	return true;
	}

	void WriteDomainName(rtc::ByteBufferWriter* buf, const std::string& name) {
	std::vector<std::string> labels;
	rtc::tokenize(name, '.', &labels);
	for (const auto& label : labels) {
	buf->WriteUInt8(label.length());
	buf->WriteString(label);
	}
	buf->WriteUInt8(0);
	}

	} // namespace

	void MDnsHeader::SetQueryOrResponse(bool is_query) {
	if (is_query) {
	flags &= ~kMDnsFlagMaskQueryOrResponse;
	} else {
	flags \|= kMDnsFlagMaskQueryOrResponse;
	}
	}

	void MDnsHeader::SetAuthoritative(bool is_authoritative) {
	if (is_authoritative) {
	flags \|= kMDnsFlagMaskAuthoritative;
	} else {
	flags &= ~kMDnsFlagMaskAuthoritative;
	}
	}

	bool MDnsHeader::IsAuthoritative() const {
	return flags & kMDnsFlagMaskAuthoritative;
	}

	bool MDnsHeader::Read(MessageBufferReader* buf) {
	if (!buf->ReadUInt16(&id) \|\| !buf->ReadUInt16(&flags) \|\|
	!buf->ReadUInt16(&qdcount) \|\| !buf->ReadUInt16(&ancount) \|\|
	!buf->ReadUInt16(&nscount) \|\| !buf->ReadUInt16(&arcount)) {
	RTC_LOG(LS_ERROR) << "Invalid mDNS header.";
	return false;
	}
	return true;
	}

	void MDnsHeader::Write(rtc::ByteBufferWriter* buf) const {
	buf->WriteUInt16(id);
	buf->WriteUInt16(flags);
	buf->WriteUInt16(qdcount);
	buf->WriteUInt16(ancount);
	buf->WriteUInt16(nscount);
	buf->WriteUInt16(arcount);
	}

	bool MDnsHeader::IsQuery() const {
	return !(flags & kMDnsFlagMaskQueryOrResponse);
	}

	MDnsSectionEntry::MDnsSectionEntry() = default;
	MDnsSectionEntry::~MDnsSectionEntry() = default;
	MDnsSectionEntry::MDnsSectionEntry(const MDnsSectionEntry& other) = default;

	void MDnsSectionEntry::SetType(SectionEntryType type) {
	switch (type) {
	case SectionEntryType::kA:
	type_ = 1;
	return;
	case SectionEntryType::kAAAA:
	type_ = 28;
	return;
	default:
	RTC_NOTREACHED();
	}
	}

	SectionEntryType MDnsSectionEntry::GetType() const {
	switch (type_) {
	case 1:
	return SectionEntryType::kA;
	case 28:
	return SectionEntryType::kAAAA;
	default:
	return SectionEntryType::kUnsupported;
	}
	}

	void MDnsSectionEntry::SetClass(SectionEntryClass cls) {
	switch (cls) {
	case SectionEntryClass::kIN:
	class_ = 1;
	return;
	default:
	RTC_NOTREACHED();
	}
	}

	SectionEntryClass MDnsSectionEntry::GetClass() const {
	switch (class_) {
	case 1:
	return SectionEntryClass::kIN;
	default:
	return SectionEntryClass::kUnsupported;
	}
	}

	MDnsQuestion::MDnsQuestion() = default;
	MDnsQuestion::MDnsQuestion(const MDnsQuestion& other) = default;
	MDnsQuestion::~MDnsQuestion() = default;

	bool MDnsQuestion::Read(MessageBufferReader* buf) {
	if (!ReadDomainName(buf, &name_)) {
	RTC_LOG(LS_ERROR) << "Invalid name.";
	return false;
	}
	if (!buf->ReadUInt16(&type_) \|\| !buf->ReadUInt16(&class_)) {
	RTC_LOG(LS_ERROR) << "Invalid type and class.";
	return false;
	}
	return true;
	}

	bool MDnsQuestion::Write(rtc::ByteBufferWriter* buf) const {
	WriteDomainName(buf, name_);
	buf->WriteUInt16(type_);
	buf->WriteUInt16(class_);
	return true;
	}

	void MDnsQuestion::SetUnicastResponse(bool should_unicast) {
	if (should_unicast) {
	class_ \|= kMDnsQClassMaskUnicastResponse;
	} else {
	class_ &= ~kMDnsQClassMaskUnicastResponse;
	}
	}

	bool MDnsQuestion::ShouldUnicastResponse() const {
	return class_ & kMDnsQClassMaskUnicastResponse;
	}

	MDnsResourceRecord::MDnsResourceRecord() = default;
	MDnsResourceRecord::MDnsResourceRecord(const MDnsResourceRecord& other) =
	default;
	MDnsResourceRecord::~MDnsResourceRecord() = default;

	bool MDnsResourceRecord::Read(MessageBufferReader* buf) {
	if (!ReadDomainName(buf, &name_)) {
	return false;
	}
	if (!buf->ReadUInt16(&type_) \|\| !buf->ReadUInt16(&class_) \|\|
	!buf->ReadUInt32(&ttl_seconds_) \|\| !buf->ReadUInt16(&rdlength_)) {
	return false;
	}

	switch (GetType()) {
	case SectionEntryType::kA:
	return ReadARData(buf);
	case SectionEntryType::kAAAA:
	return ReadQuadARData(buf);
	case SectionEntryType::kUnsupported:
	return false;
	default:
	RTC_NOTREACHED();
	}
	return false;
	}
	bool MDnsResourceRecord::ReadARData(MessageBufferReader* buf) {
	// A RDATA contains a 32-bit IPv4 address.
	return buf->ReadString(&rdata_, 4);
	}

	bool MDnsResourceRecord::ReadQuadARData(MessageBufferReader* buf) {
	// AAAA RDATA contains a 128-bit IPv6 address.
	return buf->ReadString(&rdata_, 16);
	}

	bool MDnsResourceRecord::Write(rtc::ByteBufferWriter* buf) const {
	WriteDomainName(buf, name_);
	buf->WriteUInt16(type_);
	buf->WriteUInt16(class_);
	buf->WriteUInt32(ttl_seconds_);
	buf->WriteUInt16(rdlength_);
	switch (GetType()) {
	case SectionEntryType::kA:
	WriteARData(buf);
	return true;
	case SectionEntryType::kAAAA:
	WriteQuadARData(buf);
	return true;
	case SectionEntryType::kUnsupported:
	return false;
	default:
	RTC_NOTREACHED();
	}
	return true;
	}

	void MDnsResourceRecord::WriteARData(rtc::ByteBufferWriter* buf) const {
	buf->WriteString(rdata_);
	}

	void MDnsResourceRecord::WriteQuadARData(rtc::ByteBufferWriter* buf) const {
	buf->WriteString(rdata_);
	}

	bool MDnsResourceRecord::SetIPAddressInRecordData(
	const rtc::IPAddress& address) {
	int af = address.family();
	if (af != AF_INET && af != AF_INET6) {
	return false;
	}
	char out[16] = {0};
	if (!rtc::inet_pton(af, address.ToString().c_str(), out)) {
	return false;
	}
	rdlength_ = (af == AF_INET) ? 4 : 16;
	rdata_ = std::string(out, rdlength_);
	return true;
	}

	bool MDnsResourceRecord::GetIPAddressFromRecordData(
	rtc::IPAddress* address) const {
	if (GetType() != SectionEntryType::kA &&
	GetType() != SectionEntryType::kAAAA) {
	return false;
	}
	if (rdata_.size() != 4 && rdata_.size() != 16) {
	return false;
	}
	char out[INET6_ADDRSTRLEN] = {0};
	int af = (GetType() == SectionEntryType::kA) ? AF_INET : AF_INET6;
	if (!rtc::inet_ntop(af, rdata_.data(), out, sizeof(out))) {
	return false;
	}
	return rtc::IPFromString(std::string(out), address);
	}

	MDnsMessage::MDnsMessage() = default;
	MDnsMessage::~MDnsMessage() = default;

	bool MDnsMessage::Read(MessageBufferReader* buf) {
	RTC_DCHECK_EQ(0u, buf->CurrentOffset());
	if (!header_.Read(buf)) {
	return false;
	}

	auto read_question = [&buf](std::vector<MDnsQuestion>* section,
	uint16_t count) {
	section->resize(count);
	for (auto& question : (*section)) {
	if (!question.Read(buf)) {
	return false;
	}
	}
	return true;
	};
	auto read_rr = [&buf](std::vector<MDnsResourceRecord>* section,
	uint16_t count) {
	section->resize(count);
	for (auto& rr : (*section)) {
	if (!rr.Read(buf)) {
	return false;
	}
	}
	return true;
	};

	if (!read_question(&question_section_, header_.qdcount) \|\|
	!read_rr(&answer_section_, header_.ancount) \|\|
	!read_rr(&authority_section_, header_.nscount) \|\|
	!read_rr(&additional_section_, header_.arcount)) {
	return false;
	}
	return true;
	}

	bool MDnsMessage::Write(rtc::ByteBufferWriter* buf) const {
	header_.Write(buf);

	auto write_rr = [&buf](const std::vector<MDnsResourceRecord>& section) {
	for (auto rr : section) {
	if (!rr.Write(buf)) {
	return false;
	}
	}
	return true;
	};

	for (auto question : question_section_) {
	if (!question.Write(buf)) {
	return false;
	}
	}
	if (!write_rr(answer_section_) \|\| !write_rr(authority_section_) \|\|
	!write_rr(additional_section_)) {
	return false;
	}

	return true;
	}

	bool MDnsMessage::ShouldUnicastResponse() const {
	bool should_unicast = false;
	for (const auto& question : question_section_) {
	should_unicast \|= question.ShouldUnicastResponse();
	}
	return should_unicast;
	}

	void MDnsMessage::AddQuestion(const MDnsQuestion& question) {
	question_section_.push_back(question);
	header_.qdcount = question_section_.size();
	}

	void MDnsMessage::AddAnswerRecord(const MDnsResourceRecord& answer) {
	answer_section_.push_back(answer);
	header_.ancount = answer_section_.size();
	}

	} // namespace webrtc