mDNSShared/dnssd_clientlib.c

   1 /*
   2  * Copyright (c) 2004, Apple Computer, Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are met:
   6  *
   7  * 1.  Redistributions of source code must retain the above copyright notice,
   8  *     this list of conditions and the following disclaimer.
   9  * 2.  Redistributions in binary form must reproduce the above copyright notice,
  10  *     this list of conditions and the following disclaimer in the documentation
  11  *     and/or other materials provided with the distribution.
  12  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of its
  13  *     contributors may be used to endorse or promote products derived from this
  14  *     software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
  17  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  18  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  19  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  20  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  21  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  22  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  23  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  25  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26
  27    Change History (most recent first):
  28
  29 $Log: dnssd_clientlib.c,v $
  30 Revision 1.9  2004/10/06 02:22:19  cheshire
  31 Changed MacRoman copyright symbol (should have been UTF-8 in any case :-) to ASCII-compatible "(c)"
  32
  33 Revision 1.8  2004/10/01 22:15:55  rpantos
  34 rdar://problem/3824265: Replace APSL in client lib with BSD license.
  35
  36 Revision 1.7  2004/06/26 03:16:34  shersche
  37 clean up warning messages on Win32 platform
  38
  39 Submitted by: herscher
  40
  41 Revision 1.6  2004/06/12 01:09:45  cheshire
  42 To be callable from the broadest range of clients on Windows (e.g. Visual Basic, C#, etc.)
  43 API routines have to be declared as "__stdcall", instead of the C default, "__cdecl"
  44
  45 Revision 1.5  2004/05/25 18:29:33  cheshire
  46 Move DNSServiceConstructFullName() from dnssd_clientstub.c to dnssd_clientlib.c,
  47 so that it's also accessible to dnssd_clientshim.c (single address space) clients.
  48
  49 Revision 1.4  2004/05/25 17:08:55  cheshire
  50 Fix compiler warning (doesn't make sense for function return type to be const)
  51
  52 Revision 1.3  2004/05/21 21:41:35  cheshire
  53 Add TXT record building and parsing APIs
  54
  55 Revision 1.2  2004/05/20 22:22:21  cheshire
  56 Enable code that was bracketed by "#if 0"
  57
  58 Revision 1.1  2004/03/12 21:30:29  cheshire
  59 Build a System-Context Shared Library from mDNSCore, for the benefit of developers
  60 like Muse Research who want to be able to use mDNS/DNS-SD from GPL-licensed code.
  61
  62  */
  63
  64 #include <stdlib.h>
  65 #include <string.h>
  66
  67 #include "dns_sd.h"
  68
  69 #if MDNS_BUILDINGSHAREDLIBRARY || MDNS_BUILDINGSTUBLIBRARY
  70 #pragma export on
  71 #endif
  72
  73 #if defined(_WIN32)
  74 // disable warning "conversion from <data> to uint16_t"
  75 #pragma warning(disable:4244)
  76 #endif
  77
  78 /*********************************************************************************************
  79  *
  80  *  Supporting Functions
  81  *
  82  *********************************************************************************************/
  83
  84 #define mdnsIsDigit(X)     ((X) >= '0' && (X) <= '9')
  85
  86 static int DomainEndsInDot(const char *dom)
  87         {
  88         while (dom[0] && dom[1])
  89                 {
  90                 if (dom[0] == '\\') // advance past escaped byte sequence
  91                         {
  92                         if (mdnsIsDigit(dom[1]) && mdnsIsDigit(dom[2]) && mdnsIsDigit(dom[3]))
  93                                 dom += 4;                       // If "\ddd"    then skip four
  94                         else dom += 2;                  // else if "\x" then skip two
  95                         }
  96                 else dom++;                                     // else goto next character
  97                 }
  98         return (dom[0] == '.');
  99         }
 100
 101 static uint8_t *InternalTXTRecordSearch
 102         (
 103         uint16_t         txtLen,
 104         const void       *txtRecord,
 105         const char       *key,
 106         unsigned long    *keylen
 107         )
 108         {
 109         uint8_t *p = (uint8_t*)txtRecord;
 110         uint8_t *e = p + txtLen;
 111         *keylen = (unsigned long) strlen(key);
 112         while (p<e)
 113                 {
 114                 uint8_t *x = p;
 115                 p += 1 + p[0];
 116                 if (p <= e && *keylen <= x[0] && !strncmp(key, (char*)x+1, *keylen))
 117                         if (*keylen == x[0] || x[1+*keylen] == '=') return(x);
 118                 }
 119         return(NULL);
 120         }
 121
 122 /*********************************************************************************************
 123  *
 124  *  General Utility Functions
 125  *
 126  *********************************************************************************************/
 127
 128 int DNSSD_API DNSServiceConstructFullName
 129         (
 130         char                      *fullName,
 131         const char                *service,      /* may be NULL */
 132         const char                *regtype,
 133         const char                *domain
 134         )
 135         {
 136         unsigned long len;
 137         unsigned char c;
 138         char *fn = fullName;
 139         const char *s = service;
 140         const char *r = regtype;
 141         const char *d = domain;
 142
 143         if (service)
 144                 {
 145                 while(*s)
 146                         {
 147                         c = (unsigned char)*s++;
 148                         if (c == '.' || (c == '\\')) *fn++ = '\\'; // escape dot and backslash literals
 149                         else if (c <= ' ') // escape non-printable characters
 150                                 {
 151                                 *fn++ = '\\';
 152                                 *fn++ = (char) ('0' + (c / 100));
 153                                 *fn++ = (char) ('0' + (c / 10) % 10);
 154                                 c = (unsigned char)('0' + (c % 10));
 155                                 }
 156                         *fn++ = (char)c;
 157                         }
 158                 *fn++ = '.';
 159                 }
 160
 161         if (!regtype) return -1;
 162         len = (unsigned long) strlen(regtype);
 163         if (DomainEndsInDot(regtype)) len--;
 164         if (len < 6) return -1; // regtype must be at least "x._udp" or "x._tcp"
 165         if (strncmp((regtype + len - 4), "_tcp", 4) && strncmp((regtype + len - 4), "_udp", 4)) return -1;
 166         while(*r) *fn++ = *r++;
 167         if (!DomainEndsInDot(regtype)) *fn++ = '.';
 168
 169         if (!domain || !domain[0]) return -1;
 170         while(*d) *fn++ = *d++;
 171         if (!DomainEndsInDot(domain)) *fn++ = '.';
 172         *fn = '\0';
 173         return 0;
 174         }
 175
 176 /*********************************************************************************************
 177  *
 178  *   TXT Record Construction Functions
 179  *
 180  *********************************************************************************************/
 181
 182 typedef struct _TXTRecordRefRealType
 183         {
 184         uint8_t  *buffer;               // Pointer to data
 185         uint16_t buflen;                // Length of buffer
 186         uint16_t datalen;               // Length currently in use
 187         uint16_t malloced;      // Non-zero if buffer was allocated via malloc()
 188         } TXTRecordRefRealType;
 189
 190 #define txtRec ((TXTRecordRefRealType*)txtRecord)
 191
 192 // The opaque storage defined in the public dns_sd.h header is 16 bytes;
 193 // make sure we don't exceed that.
 194 struct dnssd_clientlib_CompileTimeAssertionCheck
 195         {
 196         char assert0[(sizeof(TXTRecordRefRealType) <= 16) ? 1 : -1];
 197         };
 198
 199 void TXTRecordCreate
 200         (
 201         TXTRecordRef     *txtRecord,
 202         uint16_t         bufferLen,
 203         void             *buffer
 204         )
 205         {
 206         txtRec->buffer   = buffer;
 207         txtRec->buflen   = buffer ? bufferLen : (uint16_t)0;
 208         txtRec->datalen  = 0;
 209         txtRec->malloced = 0;
 210         }
 211
 212 void TXTRecordDeallocate(TXTRecordRef *txtRecord)
 213         {
 214         if (txtRec->malloced) free(txtRec->buffer);
 215         }
 216
 217 DNSServiceErrorType TXTRecordSetValue
 218         (
 219         TXTRecordRef     *txtRecord,
 220         const char       *key,
 221         uint8_t          valueSize,
 222         const void       *value
 223         )
 224         {
 225         uint8_t *start, *p;
 226         const char *k;
 227         unsigned long keysize, keyvalsize;
 228
 229         for (k = key; *k; k++) if (*k < 0x20 || *k > 0x7E || *k == '=') return(kDNSServiceErr_Invalid);
 230         keysize = (unsigned long)(k - key);
 231         keyvalsize = 1 + keysize + (value ? (1 + valueSize) : 0);
 232         if (keysize < 1 || keyvalsize > 255) return(kDNSServiceErr_Invalid);
 233         (void)TXTRecordRemoveValue(txtRecord, key);
 234         if (txtRec->datalen + keyvalsize > txtRec->buflen)
 235                 {
 236                 unsigned char *newbuf;
 237                 unsigned long newlen = txtRec->datalen + keyvalsize;
 238                 if (newlen > 0xFFFF) return(kDNSServiceErr_Invalid);
 239                 newbuf = malloc((size_t)newlen);
 240                 if (!newbuf) return(kDNSServiceErr_NoMemory);
 241                 memcpy(newbuf, txtRec->buffer, txtRec->datalen);
 242                 if (txtRec->malloced) free(txtRec->buffer);
 243                 txtRec->buffer = newbuf;
 244                 txtRec->buflen = (uint16_t)(newlen);
 245                 txtRec->malloced = 1;
 246                 }
 247         start = txtRec->buffer + txtRec->datalen;
 248         p = start + 1;
 249         memcpy(p, key, keysize);
 250         p += keysize;
 251         if (value)
 252                 {
 253                 *p++ = '=';
 254                 memcpy(p, value, valueSize);
 255                 p += valueSize;
 256                 }
 257         *start = (uint8_t)(p - start - 1);
 258         txtRec->datalen += p - start;
 259         return(kDNSServiceErr_NoError);
 260         }
 261
 262 DNSServiceErrorType TXTRecordRemoveValue
 263         (
 264         TXTRecordRef     *txtRecord,
 265         const char       *key
 266         )
 267         {
 268         unsigned long keylen, itemlen, remainder;
 269         uint8_t *item = InternalTXTRecordSearch(txtRec->datalen, txtRec->buffer, key, &keylen);
 270         if (!item) return(kDNSServiceErr_NoSuchKey);
 271         itemlen   = (unsigned long)(1 + item[0]);
 272         remainder = (unsigned long)((txtRec->buffer + txtRec->datalen) - (item + itemlen));
 273         // Use memmove because memcpy behaviour is undefined for overlapping regions
 274         memmove(item, item + itemlen, remainder);
 275         txtRec->datalen -= itemlen;
 276         return(kDNSServiceErr_NoError);
 277         }
 278
 279 uint16_t       TXTRecordGetLength  (const TXTRecordRef *txtRecord) { return(txtRec->datalen); }
 280 const void *   TXTRecordGetBytesPtr(const TXTRecordRef *txtRecord) { return(txtRec->buffer); }
 281
 282 /*********************************************************************************************
 283  *
 284  *   TXT Record Parsing Functions
 285  *
 286  *********************************************************************************************/
 287
 288 int TXTRecordContainsKey
 289         (
 290         uint16_t         txtLen,
 291         const void       *txtRecord,
 292         const char       *key
 293         )
 294         {
 295         unsigned long keylen;
 296         return (InternalTXTRecordSearch(txtLen, txtRecord, key, &keylen) ? 1 : 0);
 297         }
 298
 299 const void * TXTRecordGetValuePtr
 300         (
 301         uint16_t         txtLen,
 302         const void       *txtRecord,
 303         const char       *key,
 304         uint8_t          *valueLen
 305         )
 306         {
 307         unsigned long keylen;
 308         uint8_t *item = InternalTXTRecordSearch(txtLen, txtRecord, key, &keylen);
 309         if (!item || item[0] <= keylen) return(NULL);   // If key not found, or found with no value, return NULL
 310         *valueLen = (uint8_t)(item[0] - (keylen + 1));
 311         return (item + 1 + keylen + 1);
 312         }
 313
 314 uint16_t TXTRecordGetCount
 315         (
 316         uint16_t         txtLen,
 317         const void       *txtRecord
 318         )
 319         {
 320         uint16_t count = 0;
 321         uint8_t *p = (uint8_t*)txtRecord;
 322         uint8_t *e = p + txtLen;
 323         while (p<e) { p += 1 + p[0]; count++; }
 324         return((p>e) ? (uint16_t)0 : count);
 325         }
 326
 327 DNSServiceErrorType TXTRecordGetItemAtIndex
 328         (
 329         uint16_t         txtLen,
 330         const void       *txtRecord,
 331         uint16_t         index,
 332         uint16_t         keyBufLen,
 333         char             *key,
 334         uint8_t          *valueLen,
 335         const void       **value
 336         )
 337         {
 338         uint16_t count = 0;
 339         uint8_t *p = (uint8_t*)txtRecord;
 340         uint8_t *e = p + txtLen;
 341         while (p<e && count<index) { p += 1 + p[0]; count++; }  // Find requested item
 342         if (p<e && p + 1 + p[0] <= e)   // If valid
 343                 {
 344                 uint8_t *x = p+1;
 345                 unsigned long len = 0;
 346                 e = p + 1 + p[0];
 347                 while (x+len<e && x[len] != '=') len++;
 348                 if (len >= keyBufLen) return(kDNSServiceErr_NoMemory);
 349                 memcpy(key, x, len);
 350                 key[len] = 0;
 351                 if (x+len<e)            // If we found '='
 352                         {
 353                         *value = x + len + 1;
 354                         *valueLen = (uint8_t)(p[0] - (len + 1));
 355                         }
 356                 else
 357                         {
 358                         *value = NULL;
 359                         *valueLen = 0;
 360                         }
 361                 return(kDNSServiceErr_NoError);
 362                 }
 363         return(kDNSServiceErr_Invalid);
 364         }