1 /* 2 * Copyright 2018 The WebRTC Project Authors. All rights reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #ifndef P2P_BASE_MDNS_MESSAGE_H_ 12 #define P2P_BASE_MDNS_MESSAGE_H_ 13 14 // This file contains classes to read and write mDNSs message defined in RFC 15 // 6762 and RFC 1025 (DNS messages). Note that it is recommended by RFC 6762 to 16 // use the name compression scheme defined in RFC 1035 whenever possible. We 17 // currently only implement the capability of reading compressed names in mDNS 18 // messages in MdnsMessage::Read(); however, the MdnsMessage::Write() does not 19 // support name compression yet. 20 // 21 // Fuzzer tests (test/fuzzers/mdns_parser_fuzzer.cc) MUST always be performed 22 // after changes made to this file. 23 24 #include <stdint.h> 25 26 #include <string> 27 #include <vector> 28 29 #include "rtc_base/byte_buffer.h" 30 #include "rtc_base/ip_address.h" 31 #include "rtc_base/message_buffer_reader.h" 32 33 namespace webrtc { 34 35 // We use "section entry" to denote either a question or a resource record. 36 // 37 // RFC 1035 Section 3.2.2. 38 enum class SectionEntryType { 39 kA, 40 kAAAA, 41 // Only the above types are processed in the current implementation. 42 kUnsupported, 43 }; 44 45 // RFC 1035 Section 3.2.4. 46 enum class SectionEntryClass { 47 kIN, 48 kUnsupported, 49 }; 50 51 // RFC 1035, Section 4.1.1. 52 class MdnsHeader final { 53 public: 54 bool Read(MessageBufferReader* buf); 55 void Write(rtc::ByteBufferWriter* buf) const; 56 57 void SetQueryOrResponse(bool is_query); 58 bool IsQuery() const; 59 void SetAuthoritative(bool is_authoritative); 60 bool IsAuthoritative() const; 61 62 uint16_t id = 0; 63 uint16_t flags = 0; 64 // Number of entries in the question section. 65 uint16_t qdcount = 0; 66 // Number of resource records in the answer section. 67 uint16_t ancount = 0; 68 // Number of name server resource records in the authority records section. 69 uint16_t nscount = 0; 70 // Number of resource records in the additional records section. 71 uint16_t arcount = 0; 72 }; 73 74 // Entries in each section after the header share a common structure. Note that 75 // this is not a concept defined in RFC 1035. 76 class MdnsSectionEntry { 77 public: 78 MdnsSectionEntry(); 79 MdnsSectionEntry(const MdnsSectionEntry& other); 80 virtual ~MdnsSectionEntry(); 81 virtual bool Read(MessageBufferReader* buf) = 0; 82 virtual bool Write(rtc::ByteBufferWriter* buf) const = 0; 83 SetName(const std::string & name)84 void SetName(const std::string& name) { name_ = name; } 85 // Returns the fully qualified domain name in the section entry, i.e., QNAME 86 // in a question or NAME in a resource record. GetName()87 std::string GetName() const { return name_; } 88 89 void SetType(SectionEntryType type); 90 SectionEntryType GetType() const; 91 void SetClass(SectionEntryClass cls); 92 SectionEntryClass GetClass() const; 93 94 protected: 95 std::string name_; // Fully qualified domain name. 96 uint16_t type_ = 0; 97 uint16_t class_ = 0; 98 }; 99 100 // RFC 1035, Section 4.1.2. 101 class MdnsQuestion final : public MdnsSectionEntry { 102 public: 103 MdnsQuestion(); 104 MdnsQuestion(const MdnsQuestion& other); 105 ~MdnsQuestion() override; 106 107 bool Read(MessageBufferReader* buf) override; 108 bool Write(rtc::ByteBufferWriter* buf) const override; 109 110 void SetUnicastResponse(bool should_unicast); 111 bool ShouldUnicastResponse() const; 112 }; 113 114 // RFC 1035, Section 4.1.3. 115 class MdnsResourceRecord final : public MdnsSectionEntry { 116 public: 117 MdnsResourceRecord(); 118 MdnsResourceRecord(const MdnsResourceRecord& other); 119 ~MdnsResourceRecord() override; 120 121 bool Read(MessageBufferReader* buf) override; 122 bool Write(rtc::ByteBufferWriter* buf) const override; 123 SetTtlSeconds(uint32_t ttl_seconds)124 void SetTtlSeconds(uint32_t ttl_seconds) { ttl_seconds_ = ttl_seconds; } GetTtlSeconds()125 uint32_t GetTtlSeconds() const { return ttl_seconds_; } 126 // Returns true if |address| is in the address family AF_INET or AF_INET6 and 127 // |address| has a valid IPv4 or IPv6 address; false otherwise. 128 bool SetIPAddressInRecordData(const rtc::IPAddress& address); 129 // Returns true if the record is of type A or AAAA and the record has a valid 130 // IPv4 or IPv6 address; false otherwise. Stores the valid IP in |address|. 131 bool GetIPAddressFromRecordData(rtc::IPAddress* address) const; 132 133 private: 134 // The list of methods reading and writing rdata can grow as we support more 135 // types of rdata. 136 bool ReadARData(MessageBufferReader* buf); 137 void WriteARData(rtc::ByteBufferWriter* buf) const; 138 139 bool ReadQuadARData(MessageBufferReader* buf); 140 void WriteQuadARData(rtc::ByteBufferWriter* buf) const; 141 142 uint32_t ttl_seconds_ = 0; 143 uint16_t rdlength_ = 0; 144 std::string rdata_; 145 }; 146 147 class MdnsMessage final { 148 public: 149 // RFC 1035, Section 4.1. 150 enum class Section { kQuestion, kAnswer, kAuthority, kAdditional }; 151 152 MdnsMessage(); 153 ~MdnsMessage(); 154 // Reads the mDNS message in |buf| and populates the corresponding fields in 155 // MdnsMessage. 156 bool Read(MessageBufferReader* buf); 157 // Write an mDNS message to |buf| based on the fields in MdnsMessage. 158 // 159 // TODO(qingsi): Implement name compression when writing mDNS messages. 160 bool Write(rtc::ByteBufferWriter* buf) const; 161 SetId(uint16_t id)162 void SetId(uint16_t id) { header_.id = id; } GetId()163 uint16_t GetId() const { return header_.id; } 164 SetQueryOrResponse(bool is_query)165 void SetQueryOrResponse(bool is_query) { 166 header_.SetQueryOrResponse(is_query); 167 } IsQuery()168 bool IsQuery() const { return header_.IsQuery(); } 169 SetAuthoritative(bool is_authoritative)170 void SetAuthoritative(bool is_authoritative) { 171 header_.SetAuthoritative(is_authoritative); 172 } IsAuthoritative()173 bool IsAuthoritative() const { return header_.IsAuthoritative(); } 174 175 // Returns true if the message is a query and the unicast response is 176 // preferred. False otherwise. 177 bool ShouldUnicastResponse() const; 178 179 void AddQuestion(const MdnsQuestion& question); 180 // TODO(qingsi): Implement AddXRecord for name server and additional records. 181 void AddAnswerRecord(const MdnsResourceRecord& answer); 182 question_section()183 const std::vector<MdnsQuestion>& question_section() const { 184 return question_section_; 185 } answer_section()186 const std::vector<MdnsResourceRecord>& answer_section() const { 187 return answer_section_; 188 } authority_section()189 const std::vector<MdnsResourceRecord>& authority_section() const { 190 return authority_section_; 191 } additional_section()192 const std::vector<MdnsResourceRecord>& additional_section() const { 193 return additional_section_; 194 } 195 196 private: 197 MdnsHeader header_; 198 std::vector<MdnsQuestion> question_section_; 199 std::vector<MdnsResourceRecord> answer_section_; 200 std::vector<MdnsResourceRecord> authority_section_; 201 std::vector<MdnsResourceRecord> additional_section_; 202 }; 203 204 } // namespace webrtc 205 206 #endif // P2P_BASE_MDNS_MESSAGE_H_ 207