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      1 /*
      2  * Copyright (c) 2002-2021 Apple Inc. All rights reserved.
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *     https://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef __UDNS_H_
     18 #define __UDNS_H_
     19 
     20 #include "nullability.h"
     21 #include "mDNSEmbeddedAPI.h"
     22 #include "DNSCommon.h"
     23 #include <sys/types.h>
     24 
     25 #if MDNSRESPONDER_SUPPORTS(COMMON, DNS_PUSH)
     26 #include "dso.h"
     27 #include "dso-transport.h"
     28 #endif
     29 
     30 #ifdef  __cplusplus
     31 extern "C" {
     32 #endif
     33 
     34 #define RESTART_GOODBYE_DELAY    (6 * mDNSPlatformOneSecond) // delay after restarting LLQ before nuking previous known answers (avoids flutter if we restart before we have networking up)
     35 #define INIT_UCAST_POLL_INTERVAL (3 * mDNSPlatformOneSecond) // this interval is used after send failures on network transitions
     36                                                              // which typically heal quickly, so we start agressively and exponentially back off
     37 #define MAX_UCAST_POLL_INTERVAL (60 * 60 * mDNSPlatformOneSecond)
     38 //#define MAX_UCAST_POLL_INTERVAL (1 * 60 * mDNSPlatformOneSecond)
     39 #define LLQ_POLL_INTERVAL_MIN   15
     40 #define LLQ_POLL_INTERVAL       (LLQ_POLL_INTERVAL_MIN * 60 * mDNSPlatformOneSecond) // Polling interval for zones w/ an advertised LLQ port (ie not static zones) if LLQ fails due to NAT, etc.
     41 #define RESPONSE_WINDOW (60 * mDNSPlatformOneSecond)         // require server responses within one minute of request
     42 #define MAX_UCAST_UNANSWERED_QUERIES 2                       // number of unanswered queries from any one uDNS server before trying another server
     43 #define DNSSERVER_PENALTY_TIME (60 * mDNSPlatformOneSecond)  // number of seconds for which new questions don't pick this server
     44 
     45 // On some interfaces, we want to delay the first retransmission to a minimum of 2 seconds
     46 // rather than the default (1 second).
     47 #define MIN_UCAST_RETRANS_TIMEOUT (2 * mDNSPlatformOneSecond)
     48 
     49 #define DEFAULT_UPDATE_LEASE 7200
     50 
     51 #define QuestionIntervalStep 3
     52 #define QuestionIntervalStep2 (QuestionIntervalStep*QuestionIntervalStep)
     53 #define QuestionIntervalStep3 (QuestionIntervalStep*QuestionIntervalStep*QuestionIntervalStep)
     54 #define InitialQuestionInterval ((mDNSPlatformOneSecond + QuestionIntervalStep-1) / QuestionIntervalStep)
     55 #define MaxQuestionInterval         (3600 * mDNSPlatformOneSecond)
     56 #define UDNSBackOffMultiplier 2
     57 #define MinQuestionInterval (1 * mDNSPlatformOneSecond)
     58 
     59 // For Unicast record registrations, we initialize the interval to 1 second. When we send any query for
     60 // the record registration e.g., GetZoneData, we always back off by QuestionIntervalStep
     61 // so that the first retry does not happen until 3 seconds which should be enough for TCP/TLS to be done.
     62 #define INIT_RECORD_REG_INTERVAL (1 * mDNSPlatformOneSecond)
     63 #define MAX_RECORD_REG_INTERVAL (15 * 60 * mDNSPlatformOneSecond)
     64 #define MERGE_DELAY_TIME    (1 * mDNSPlatformOneSecond)
     65 
     66 // If we are refreshing, we do it at least 5 times with a min update frequency of
     67 // 5 minutes
     68 #define MAX_UPDATE_REFRESH_COUNT    5
     69 #define MIN_UPDATE_REFRESH_TIME     (5 * 60 * mDNSPlatformOneSecond)
     70 
     71 // For questions that use kDNSServiceFlagsTimeout and we don't have a matching resolver e.g., no dns servers,
     72 // then use the default value of 30 seconds
     73 #define DEFAULT_UDNS_TIMEOUT    30 // in seconds
     74 
     75 #if MDNSRESPONDER_SUPPORTS(COMMON, DNS_PUSH)
     76 
     77 // Reference count helper for DNSPushServer and DNSPushZone.
     78 #define DNS_PUSH_RETAIN(OBJ)                                                                                    \
     79     do                                                                                                          \
     80     {                                                                                                           \
     81         (OBJ)->refCount++;                                                                                      \
     82         LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEBUG,                                                    \
     83             "DNS push object retained - object: %p, refCount after retaining: %u.", (OBJ), (OBJ)->refCount);    \
     84     } while (mDNSfalse)
     85 
     86 #define DNS_PUSH_RELEASE(OBJ, FINALIZER)                                                                        \
     87     do                                                                                                          \
     88     {                                                                                                           \
     89         (OBJ)->refCount--;                                                                                      \
     90         LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEBUG,                                                    \
     91             "DNS push object released - object: %p, refCount after releasing: %u.", (OBJ), (OBJ)->refCount);    \
     92         if ((OBJ)->refCount == 0)                                                                               \
     93         {                                                                                                       \
     94             FINALIZER((OBJ));                                                                                   \
     95             (OBJ) = NULL;                                                                                       \
     96         }                                                                                                       \
     97     } while (mDNSfalse)
     98 
     99 // Push notification structures.
    100 struct mDNS_DNSPushServer
    101 {
    102     uint32_t                   serial;            // The serial number that can be used to identify a specific server.
    103     uint32_t                   refCount;          // Reference count used by DNS_PUSH_RETAIN and DNS_PUSH_RELEASE.
    104     dso_connect_state_t       *connectInfo;       // DSO Connection state information.
    105     dso_state_t               *connection;        // DNS Stateful Operations/TCP Connection pointer, might be null.
    106     DNSPushServer_ConnectState connectState;      // Current status of connection attempt to this server.
    107     mDNSs32                    lastDisconnect;    // Last time we got a disconnect, used to avoid constant reconnects.
    108     domainname                 serverName;        // The hostname returned by the _dns-push-tls._tcp.<zone> SRV lookup.
    109     mDNSIPPort                 port;              // The port from the SRV lookup.
    110 #if MDNSRESPONDER_SUPPORTS(APPLE, QUERIER)
    111     mdns_dns_service_t         dnsservice;
    112 #else
    113     DNSServer                 *qDNSServer;        // DNS server stolen from the question that created this server structure.
    114 #endif
    115     mDNS                      *m;
    116     mDNSBool                   canceling;         // Indicates if the current server is being canceled.
    117     DNSPushServer *next;
    118 } ;
    119 
    120 struct mDNS_DNSPushZone
    121 {
    122     uint32_t refCount;                // Reference count used by DNS_PUSH_RETAIN and DNS_PUSH_RELEASE.
    123     domainname zoneName;
    124     DNSPushServer *server; // DNS Push Servers for this zone.
    125     DNSPushZone *next;
    126 } ;
    127 #endif
    128 
    129 // Entry points into unicast-specific routines
    130 
    131 extern void LLQGotZoneData(mDNS *const m, mStatus err, const ZoneData *zoneInfo);
    132 extern void startLLQHandshake(mDNS *m, DNSQuestion *q);
    133 extern void sendLLQRefresh(mDNS *m, DNSQuestion *q);
    134 
    135 #if MDNSRESPONDER_SUPPORTS(COMMON, DNS_PUSH)
    136 extern void DNSPushGotZoneData(mDNS *m, mStatus err, const ZoneData *zoneInfo);
    137 extern void DiscoverDNSPushServer(mDNS *m, DNSQuestion *q);
    138 extern void UnsubscribeQuestionFromDNSPushServer(mDNS *m, DNSQuestion *q, mDNSBool fallBackToLLQPoll);
    139 extern void UnsubscribeAllQuestionsFromDNSPushServer(mDNS *m, DNSPushServer *server);
    140 extern void DNSPushZoneRemove(mDNS *m, const DNSPushServer *server);
    141 extern void DNSPushZoneFinalize(DNSPushZone *zone);
    142 extern mDNSInterfaceID DNSPushServerGetInterfaceID(mDNS *m, const DNSPushServer *server);
    143 extern void DNSPushServerCancel(DNSPushServer *server, mDNSBool alreadyRemovedFromSystem);
    144 extern void DNSPushServerFinalize(DNSPushServer *server);
    145 extern void DNSPushUpdateQuestionDuplicate(DNSQuestion *primary, DNSQuestion *duplicate);
    146 #endif
    147 
    148 extern void GetZoneData_QuestionCallback(mDNS *m, DNSQuestion *question, const ResourceRecord *answer,
    149     QC_result AddRecord);
    150 
    151 extern void SleepRecordRegistrations(mDNS *m);
    152 
    153 // uDNS_UpdateRecord
    154 // following fields must be set, and the update validated, upon entry.
    155 // rr->NewRData
    156 // rr->newrdlength
    157 // rr->UpdateCallback
    158 
    159 extern mStatus uDNS_UpdateRecord(mDNS *m, AuthRecord *rr);
    160 
    161 extern void SetNextQueryTime(mDNS *const m, const DNSQuestion *const q);
    162 extern mStatus mDNS_Register_internal(mDNS *const m, AuthRecord *const rr);
    163 extern mStatus mDNS_Deregister_internal(mDNS *const m, AuthRecord *const rr, mDNS_Dereg_type drt);
    164 extern mStatus mDNS_StartQuery_internal(mDNS *const m, DNSQuestion *const question);
    165 extern mStatus mDNS_StopQuery_internal(mDNS *const m, DNSQuestion *const question);
    166 extern mStatus mDNS_StartNATOperation_internal(mDNS *const m, NATTraversalInfo *traversal);
    167 
    168 extern void RecordRegistrationGotZoneData(mDNS *const m, mStatus err, const ZoneData *zoneData);
    169 extern mStatus uDNS_DeregisterRecord(mDNS *const m, AuthRecord *const rr);
    170 extern const domainname *GetServiceTarget(mDNS *m, AuthRecord *const rr);
    171 
    172 // integer fields of msg header must be in HOST byte order before calling this routine
    173 extern void uDNS_ReceiveMsg(mDNS *const m, DNSMessage *const msg, const mDNSu8 *const end,
    174                             const mDNSAddr *const srcaddr, const mDNSIPPort srcport);
    175 
    176 extern void uDNS_Tasks(mDNS *const m);
    177 extern void UpdateAllSRVRecords(mDNS *m);
    178 extern void CheckNATMappings(mDNS *m);
    179 
    180 extern mStatus         uDNS_SetupDNSConfig(mDNS *const m);
    181 
    182 // uDNS_SetupWABQueries reads search domains from the platform layer and starts the Wide Area Bonjour
    183 // (WAB) domain enumeration queries if necessary.
    184 
    185 #define UDNS_WAB_BROWSE_QUERY    0x00000001 // Browse queries (b, db)
    186 #define UDNS_WAB_LBROWSE_QUERY   0x00000002 // Browse queries (lb)
    187 #define UDNS_WAB_REG_QUERY       0x00000004 // Registration queries (r and dr)
    188 
    189 extern void uDNS_SetupWABQueries(mDNS *const m);
    190 extern void uDNS_StartWABQueries(mDNS *const m, int queryType);
    191 extern void uDNS_StopWABQueries(mDNS *const m, int queryType);
    192 extern domainname      *uDNS_GetNextSearchDomain(mDNSInterfaceID InterfaceID, int *searchIndex, mDNSBool ignoreDotLocal);
    193 
    194 extern void uDNS_RestartQuestionAsTCP(mDNS *m, DNSQuestion *const q, const mDNSAddr *const srcaddr, const mDNSIPPort srcport);
    195 
    196 extern uDNS_LLQType    uDNS_recvLLQResponse(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end, const mDNSAddr *const srcaddr, const mDNSIPPort srcport, DNSQuestion **matchQuestion);
    197 extern DomainAuthInfo *GetAuthInfoForName_internal(mDNS *m, const domainname *const name);
    198 extern DomainAuthInfo *GetAuthInfoForQuestion(mDNS *m, const DNSQuestion *const q);
    199 extern void DisposeTCPConn(struct tcpInfo_t *tcp);
    200 
    201 // NAT traversal
    202 extern void uDNS_ReceiveNATPacket(mDNS *m, const mDNSInterfaceID InterfaceID, mDNSu8 *pkt, mDNSu16 len); // Called for each received PCP or NAT-PMP packet
    203 extern void natTraversalHandleAddressReply(mDNS *const m, mDNSu16 err, mDNSv4Addr ExtAddr);
    204 extern void natTraversalHandlePortMapReply(mDNS *const m, NATTraversalInfo *n, const mDNSInterfaceID InterfaceID, mDNSu16 err, mDNSIPPort extport, mDNSu32 lease, NATTProtocol protocol);
    205 
    206 extern CacheRecord* mDNSCoreReceiveCacheCheck(mDNS *const m, const DNSMessage *const response, uDNS_LLQType LLQType,
    207 											  const mDNSu32 slot, CacheGroup *cg,
    208                                               CacheRecord ***cfp, mDNSInterfaceID InterfaceID);
    209 #ifdef  __cplusplus
    210 }
    211 #endif
    212 
    213 #endif // __UDNS_H_
    214