1/* -*- Mode: C; tab-width: 4 -*-
2 *
3 * Copyright (c) 2002-2018 Apple Inc. All rights reserved.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18#ifndef __DNSCOMMON_H_
19#define __DNSCOMMON_H_
20
21#include "mDNSEmbeddedAPI.h"
22
23#ifdef  __cplusplus
24extern "C" {
25#endif
26
27//*************************************************************************************************************
28// Macros
29
30// Note: The C preprocessor stringify operator ('#') makes a string from its argument, without macro expansion
31// e.g. If "version" is #define'd to be "4", then STRINGIFY_AWE(version) will return the string "version", not "4"
32// To expand "version" to its value before making the string, use STRINGIFY(version) instead
33#define STRINGIFY_ARGUMENT_WITHOUT_EXPANSION(s) # s
34#define STRINGIFY(s) STRINGIFY_ARGUMENT_WITHOUT_EXPANSION(s)
35
36// ***************************************************************************
37#if COMPILER_LIKES_PRAGMA_MARK
38#pragma mark - DNS Protocol Constants
39#endif
40
41typedef enum
42{
43    kDNSFlag0_QR_Mask        = 0x80,    // Query or response?
44    kDNSFlag0_QR_Query       = 0x00,
45    kDNSFlag0_QR_Response    = 0x80,
46
47    kDNSFlag0_OP_Mask        = 0x78,    // Operation type
48    kDNSFlag0_OP_StdQuery    = 0x00,
49    kDNSFlag0_OP_Subscribe   = 0x06,
50    kDNSFlag0_OP_UnSubscribe = 0x07,
51    kDNSFlag0_OP_Iquery      = 0x08,
52    kDNSFlag0_OP_Status      = 0x10,
53    kDNSFlag0_OP_Unused3     = 0x18,
54    kDNSFlag0_OP_Notify      = 0x20,
55    kDNSFlag0_OP_Update      = 0x28,
56
57    kDNSFlag0_QROP_Mask   = kDNSFlag0_QR_Mask | kDNSFlag0_OP_Mask,
58
59    kDNSFlag0_AA          = 0x04,       // Authoritative Answer?
60    kDNSFlag0_TC          = 0x02,       // Truncated?
61    kDNSFlag0_RD          = 0x01,       // Recursion Desired?
62    kDNSFlag1_RA          = 0x80,       // Recursion Available?
63
64    kDNSFlag1_Zero        = 0x40,       // Reserved; must be zero
65    kDNSFlag1_AD          = 0x20,       // Authentic Data [RFC 2535]
66    kDNSFlag1_CD          = 0x10,       // Checking Disabled [RFC 2535]
67
68    kDNSFlag1_RC_Mask     = 0x0F,       // Response code
69    kDNSFlag1_RC_NoErr    = 0x00,
70    kDNSFlag1_RC_FormErr  = 0x01,
71    kDNSFlag1_RC_ServFail = 0x02,
72    kDNSFlag1_RC_NXDomain = 0x03,
73    kDNSFlag1_RC_NotImpl  = 0x04,
74    kDNSFlag1_RC_Refused  = 0x05,
75    kDNSFlag1_RC_YXDomain = 0x06,
76    kDNSFlag1_RC_YXRRSet  = 0x07,
77    kDNSFlag1_RC_NXRRSet  = 0x08,
78    kDNSFlag1_RC_NotAuth  = 0x09,
79    kDNSFlag1_RC_NotZone  = 0x0A
80} DNS_Flags;
81
82typedef enum
83{
84    TSIG_ErrBadSig  = 16,
85    TSIG_ErrBadKey  = 17,
86    TSIG_ErrBadTime = 18
87} TSIG_ErrorCode;
88
89
90// ***************************************************************************
91#if COMPILER_LIKES_PRAGMA_MARK
92#pragma mark -
93#pragma mark - General Utility Functions
94#endif
95
96extern NetworkInterfaceInfo *GetFirstActiveInterface(NetworkInterfaceInfo *intf);
97extern mDNSInterfaceID GetNextActiveInterfaceID(const NetworkInterfaceInfo *intf);
98
99extern mDNSu32 mDNSRandom(mDNSu32 max);     // Returns pseudo-random result from zero to max inclusive
100
101// ***************************************************************************
102#if COMPILER_LIKES_PRAGMA_MARK
103#pragma mark -
104#pragma mark - Domain Name Utility Functions
105#endif
106
107#define mDNSSubTypeLabel   "\x04_sub"
108
109#define mDNSIsDigit(X)     ((X) >= '0' && (X) <= '9')
110#define mDNSIsUpperCase(X) ((X) >= 'A' && (X) <= 'Z')
111#define mDNSIsLowerCase(X) ((X) >= 'a' && (X) <= 'z')
112#define mDNSIsLetter(X)    (mDNSIsUpperCase(X) || mDNSIsLowerCase(X))
113
114// We believe we have adequate safeguards to protect against cache poisoning.
115// In the event that someone does find a workable cache poisoning attack, we want to limit the lifetime of the poisoned entry.
116// We set the maximum allowable TTL to one hour.
117// With the 25% correction factor to avoid the DNS Zeno's paradox bug, that gives us an actual maximum lifetime of 75 minutes.
118
119#define mDNSMaximumTTLSeconds (mDNSu32)3600
120
121#define mDNSValidHostChar(X, notfirst, notlast) (mDNSIsLetter(X) || mDNSIsDigit(X) || ((notfirst) && (notlast) && (X) == '-') )
122
123extern mDNSu16 CompressedDomainNameLength(const domainname *const name, const domainname *parent);
124extern int CountLabels(const domainname *d);
125extern const domainname *SkipLeadingLabels(const domainname *d, int skip);
126
127extern mDNSu32 TruncateUTF8ToLength(mDNSu8 *string, mDNSu32 length, mDNSu32 max);
128extern mDNSBool LabelContainsSuffix(const domainlabel *const name, const mDNSBool RichText);
129extern mDNSu32 RemoveLabelSuffix(domainlabel *name, mDNSBool RichText);
130extern void AppendLabelSuffix(domainlabel *const name, mDNSu32 val, const mDNSBool RichText);
131#define ValidateDomainName(N) (DomainNameLength(N) <= MAX_DOMAIN_NAME)
132
133// ***************************************************************************
134#if COMPILER_LIKES_PRAGMA_MARK
135#pragma mark -
136#pragma mark - Resource Record Utility Functions
137#endif
138
139// IdenticalResourceRecord returns true if two resources records have
140// the same name, type, class, and identical rdata (InterfaceID and TTL may differ)
141
142// IdenticalSameNameRecord is the same, except it skips the expensive SameDomainName() check,
143// which is at its most expensive and least useful in cases where we know in advance that the names match
144
145// Note: The dominant use of IdenticalResourceRecord is from ProcessQuery(), handling known-answer lists. In this case
146// it's common to have a whole bunch or records with exactly the same name (e.g. "_http._tcp.local") but different RDATA.
147// The SameDomainName() check is expensive when the names match, and in this case *all* the names match, so we
148// used to waste a lot of CPU time verifying that the names match, only then to find that the RDATA is different.
149// We observed mDNSResponder spending 30% of its total CPU time on this single task alone.
150// By swapping the checks so that we check the RDATA first, we can quickly detect when it's different
151// (99% of the time) and then bail out before we waste time on the expensive SameDomainName() check.
152
153#define IdenticalResourceRecord(r1,r2) ( \
154        (r1)->rrtype    == (r2)->rrtype      && \
155        (r1)->rrclass   == (r2)->rrclass     && \
156        (r1)->namehash  == (r2)->namehash    && \
157        (r1)->rdlength  == (r2)->rdlength    && \
158        (r1)->rdatahash == (r2)->rdatahash   && \
159        SameRDataBody((r1), &(r2)->rdata->u, SameDomainName) && \
160        SameDomainName((r1)->name, (r2)->name))
161
162#define IdenticalSameNameRecord(r1,r2) ( \
163        (r1)->rrtype    == (r2)->rrtype      && \
164        (r1)->rrclass   == (r2)->rrclass     && \
165        (r1)->rdlength  == (r2)->rdlength    && \
166        (r1)->rdatahash == (r2)->rdatahash   && \
167        SameRDataBody((r1), &(r2)->rdata->u, SameDomainName))
168
169// A given RRType answers a QuestionType if RRType is CNAME, or types match, or QuestionType is ANY,
170// or the RRType is NSEC and positively asserts the nonexistence of the type being requested
171#define RRTypeAnswersQuestionType(R,Q) ((R)->rrtype == kDNSType_CNAME || (R)->rrtype == (Q) || (Q) == kDNSQType_ANY || RRAssertsNonexistence((R),(Q)))
172// Unicast NSEC records have the NSEC bit set whereas the multicast NSEC ones don't
173#define UNICAST_NSEC(rr) ((rr)->rrtype == kDNSType_NSEC && RRAssertsExistence((rr), kDNSType_NSEC))
174
175extern mDNSu32 RDataHashValue(const ResourceRecord *const rr);
176extern mDNSBool SameRDataBody(const ResourceRecord *const r1, const RDataBody *const r2, DomainNameComparisonFn *samename);
177extern mDNSBool SameNameRecordAnswersQuestion(const ResourceRecord *const rr, const DNSQuestion *const q);
178extern mDNSBool ResourceRecordAnswersQuestion(const ResourceRecord *const rr, const DNSQuestion *const q);
179extern mDNSBool AnyTypeRecordAnswersQuestion (const ResourceRecord *const rr, const DNSQuestion *const q);
180extern mDNSBool ResourceRecordAnswersUnicastResponse(const ResourceRecord *const rr, const DNSQuestion *const q);
181extern mDNSBool LocalOnlyRecordAnswersQuestion(AuthRecord *const rr, const DNSQuestion *const q);
182extern mDNSu16 GetRDLength(const ResourceRecord *const rr, mDNSBool estimate);
183extern mDNSBool ValidateRData(const mDNSu16 rrtype, const mDNSu16 rdlength, const RData *const rd);
184extern mStatus DNSNameToLowerCase(domainname *d, domainname *result);
185
186#define GetRRDomainNameTarget(RR) (                                                                          \
187        ((RR)->rrtype == kDNSType_NS || (RR)->rrtype == kDNSType_CNAME || (RR)->rrtype == kDNSType_PTR || (RR)->rrtype == kDNSType_DNAME) ? &(RR)->rdata->u.name        : \
188        ((RR)->rrtype == kDNSType_MX || (RR)->rrtype == kDNSType_AFSDB || (RR)->rrtype == kDNSType_RT  || (RR)->rrtype == kDNSType_KX   ) ? &(RR)->rdata->u.mx.exchange : \
189        ((RR)->rrtype == kDNSType_SRV                                  ) ? &(RR)->rdata->u.srv.target : mDNSNULL )
190
191#define LocalRecordReady(X) ((X)->resrec.RecordType != kDNSRecordTypeUnique)
192
193// ***************************************************************************
194#if COMPILER_LIKES_PRAGMA_MARK
195#pragma mark -
196#pragma mark - DNS Message Creation Functions
197#endif
198
199extern void InitializeDNSMessage(DNSMessageHeader *h, mDNSOpaque16 id, mDNSOpaque16 flags);
200extern const mDNSu8 *FindCompressionPointer(const mDNSu8 *const base, const mDNSu8 *const end, const mDNSu8 *const domname);
201extern mDNSu8 *putDomainNameAsLabels(const DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const domainname *const name);
202extern mDNSu8 *putRData(const DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const ResourceRecord *const rr);
203
204// If we have a single large record to put in the packet, then we allow the packet to be up to 9K bytes,
205// but in the normal case we try to keep the packets below 1500 to avoid IP fragmentation on standard Ethernet
206
207#define AllowedRRSpace(msg) (((msg)->h.numAnswers || (msg)->h.numAuthorities || (msg)->h.numAdditionals) ? NormalMaxDNSMessageData : AbsoluteMaxDNSMessageData)
208
209extern mDNSu8 *PutResourceRecordTTLWithLimit(DNSMessage *const msg, mDNSu8 *ptr, mDNSu16 *count, ResourceRecord *rr, mDNSu32 ttl, const mDNSu8 *limit);
210
211#define PutResourceRecordTTL(msg, ptr, count, rr, ttl) \
212    PutResourceRecordTTLWithLimit((msg), (ptr), (count), (rr), (ttl), (msg)->data + AllowedRRSpace(msg))
213
214#define PutResourceRecordTTLJumbo(msg, ptr, count, rr, ttl) \
215    PutResourceRecordTTLWithLimit((msg), (ptr), (count), (rr), (ttl), (msg)->data + AbsoluteMaxDNSMessageData)
216
217#define PutResourceRecord(MSG, P, C, RR) PutResourceRecordTTL((MSG), (P), (C), (RR), (RR)->rroriginalttl)
218
219// The PutRR_OS variants assume a local variable 'm', put build the packet at m->omsg,
220// and assume local variables 'OwnerRecordSpace' & 'TraceRecordSpace' indicating how many bytes (if any) to reserve to add an OWNER/TRACER option at the end
221#define PutRR_OS_TTL(ptr, count, rr, ttl) \
222    PutResourceRecordTTLWithLimit(&m->omsg, (ptr), (count), (rr), (ttl), m->omsg.data + AllowedRRSpace(&m->omsg) - OwnerRecordSpace - TraceRecordSpace)
223
224#define PutRR_OS(P, C, RR) PutRR_OS_TTL((P), (C), (RR), (RR)->rroriginalttl)
225
226extern mDNSu8 *putQuestion(DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const domainname *const name, mDNSu16 rrtype, mDNSu16 rrclass);
227extern mDNSu8 *putZone(DNSMessage *const msg, mDNSu8 *ptr, mDNSu8 *limit, const domainname *zone, mDNSOpaque16 zoneClass);
228extern mDNSu8 *putPrereqNameNotInUse(const domainname *const name, DNSMessage *const msg, mDNSu8 *const ptr, mDNSu8 *const end);
229extern mDNSu8 *putDeletionRecord(DNSMessage *msg, mDNSu8 *ptr, ResourceRecord *rr);
230extern mDNSu8 *putDeletionRecordWithLimit(DNSMessage *msg, mDNSu8 *ptr, ResourceRecord *rr, mDNSu8 *limit);
231extern mDNSu8 *putDeleteRRSetWithLimit(DNSMessage *msg, mDNSu8 *ptr, const domainname *name, mDNSu16 rrtype, mDNSu8 *limit);
232extern mDNSu8 *putDeleteAllRRSets(DNSMessage *msg, mDNSu8 *ptr, const domainname *name);
233extern mDNSu8 *putUpdateLease(DNSMessage *msg, mDNSu8 *ptr, mDNSu32 lease);
234extern mDNSu8 *putUpdateLeaseWithLimit(DNSMessage *msg, mDNSu8 *ptr, mDNSu32 lease, mDNSu8 *limit);
235
236extern mDNSu8 *putHINFO(const mDNS *const m, DNSMessage *const msg, mDNSu8 *ptr, DomainAuthInfo *authInfo, mDNSu8 *limit);
237extern mDNSu8 *putDNSSECOption(DNSMessage *msg, mDNSu8 *end, mDNSu8 *limit);
238extern int baseEncode(char *buffer, int blen, const mDNSu8 *data, int len, int encAlg);
239extern void NSEC3Parse(const ResourceRecord *const rr, mDNSu8 **salt, int *hashLength, mDNSu8 **nxtName, int *bitmaplen, mDNSu8 **bitmap);
240
241extern const mDNSu8 *NSEC3HashName(const domainname *name, rdataNSEC3 *nsec3, const mDNSu8 *AnonData, int AnonDataLen,
242    const mDNSu8 hash[NSEC3_MAX_HASH_LEN], int *dlen);
243
244// ***************************************************************************
245#if COMPILER_LIKES_PRAGMA_MARK
246#pragma mark -
247#pragma mark - DNS Message Parsing Functions
248#endif
249
250#define HashSlotFromNameHash(X) ((X) % CACHE_HASH_SLOTS)
251extern mDNSu32 DomainNameHashValue(const domainname *const name);
252extern void SetNewRData(ResourceRecord *const rr, RData *NewRData, mDNSu16 rdlength);
253extern const mDNSu8 *skipDomainName(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *const end);
254extern const mDNSu8 *getDomainName(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *const end,
255                                   domainname *const name);
256extern const mDNSu8 *skipResourceRecord(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end);
257extern const mDNSu8 *GetLargeResourceRecord(mDNS *const m, const DNSMessage * const msg, const mDNSu8 *ptr,
258                                            const mDNSu8 * end, const mDNSInterfaceID InterfaceID, mDNSu8 RecordType, LargeCacheRecord *const largecr);
259extern mDNSBool SetRData(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *end,
260    LargeCacheRecord *const largecr, mDNSu16 rdlength);
261extern const mDNSu8 *skipQuestion(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end);
262extern const mDNSu8 *getQuestion(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end, const mDNSInterfaceID InterfaceID,
263                                 DNSQuestion *question);
264extern const mDNSu8 *LocateAnswers(const DNSMessage *const msg, const mDNSu8 *const end);
265extern const mDNSu8 *LocateAuthorities(const DNSMessage *const msg, const mDNSu8 *const end);
266extern const mDNSu8 *LocateAdditionals(const DNSMessage *const msg, const mDNSu8 *const end);
267extern const mDNSu8 *LocateOptRR(const DNSMessage *const msg, const mDNSu8 *const end, int minsize);
268extern const rdataOPT *GetLLQOptData(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end);
269extern mDNSBool GetPktLease(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end, mDNSu32 *const lease);
270extern void DumpPacket(mStatus status, mDNSBool sent, char *transport,
271                       const mDNSAddr *srcaddr, mDNSIPPort srcport,
272                       const mDNSAddr *dstaddr, mDNSIPPort dstport, const DNSMessage *const msg, const mDNSu8 *const end);
273extern mDNSBool RRAssertsNonexistence(const ResourceRecord *const rr, mDNSu16 type);
274extern mDNSBool RRAssertsExistence(const ResourceRecord *const rr, mDNSu16 type);
275extern mDNSBool BitmapTypeCheck(mDNSu8 *bmap, int bitmaplen, mDNSu16 type);
276
277extern mDNSu16 swap16(mDNSu16 x);
278extern mDNSu32 swap32(mDNSu32 x);
279
280// ***************************************************************************
281#if COMPILER_LIKES_PRAGMA_MARK
282#pragma mark -
283#pragma mark - Packet Sending Functions
284#endif
285
286extern mStatus mDNSSendDNSMessage(mDNS *const m, DNSMessage *const msg, mDNSu8 *end,
287                                  mDNSInterfaceID InterfaceID, UDPSocket *src, const mDNSAddr *dst,
288                                  mDNSIPPort dstport, TCPSocket *sock, DomainAuthInfo *authInfo,
289                                  mDNSBool useBackgroundTrafficClass);
290
291// ***************************************************************************
292#if COMPILER_LIKES_PRAGMA_MARK
293#pragma mark -
294#pragma mark - RR List Management & Task Management
295#endif
296
297extern void ShowTaskSchedulingError(mDNS *const m);
298extern void mDNS_Lock_(mDNS *const m, const char * const functionname);
299extern void mDNS_Unlock_(mDNS *const m, const char * const functionname);
300
301#if defined(_WIN32)
302 #define __func__ __FUNCTION__
303#endif
304
305#define mDNS_Lock(X) mDNS_Lock_((X), __func__)
306
307#define mDNS_Unlock(X) mDNS_Unlock_((X), __func__)
308
309#define mDNS_CheckLock(X) \
310    if ((X)->mDNS_busy != (X)->mDNS_reentrancy+1) LogMsg("%s: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", __func__, (X)->mDNS_busy, (X)->mDNS_reentrancy)
311
312#define mDNS_DropLockBeforeCallback() do { m->mDNS_reentrancy++; \
313    if (m->mDNS_busy != m->mDNS_reentrancy) LogMsg("%s: Locking Failure! mDNS_busy (%ld) != mDNS_reentrancy (%ld)", __func__, m->mDNS_busy, m->mDNS_reentrancy); \
314    } while (0)
315
316#define mDNS_ReclaimLockAfterCallback() do { \
317    if (m->mDNS_busy != m->mDNS_reentrancy) LogMsg("%s: Unlocking Failure! mDNS_busy (%ld) != mDNS_reentrancy (%ld)", __func__, m->mDNS_busy, m->mDNS_reentrancy); \
318    m->mDNS_reentrancy--; } while (0)
319
320#ifdef  __cplusplus
321}
322#endif
323
324#endif // __DNSCOMMON_H_
325