mdw@git.distorted.org.uk Git - adns/blob - src/adns.c

   1 /**/
   2
   3 #include <stdarg.h>
   4 #include <stdio.h>
   5 #include <errno.h>
   6 #include <string.h>
   7 #include <stdlib.h>
   8 #include <assert.h>
   9 #include <unistd.h>
  10
  11 #include <netdb.h>
  12 #include <arpa/nameser.h>
  13 #include <sys/socket.h>
  14 #include <netinet/in.h>
  15 #include <arpa/inet.h>
  16
  17 #include "adns-internal.h"
  18
  19 #define LIST_UNLINK(list,node) \
  20   do { \
  21     if ((node)->back) (node)->back->next= (node)->next; \
  22       else                   (list).head= (node)->next; \
  23     if ((node)->next) (node)->next->back= (node)->back; \
  24       else                   (list).tail= (node)->back; \
  25   } while(0)
  26
  27 #define LIST_LINK_TAIL(list,node) \
  28   do { \
  29     (node)->back= 0; \
  30     (node)->next= (list).tail; \
  31     if ((list).tail) (list).tail->back= (node); else (list).head= (node); \
  32     (list).tail= (node); \
  33   } while(0)
  34
  35 static void vdebug(adns_state ads, const char *fmt, va_list al) {
  36   if (!(ads->iflags & adns_if_debug)) return;
  37   fputs("adns debug: ",stderr);
  38   vfprintf(stderr,fmt,al);
  39   fputc('\n',stderr);
  40 }
  41
  42 static void debug(adns_state ads, const char *fmt, ...) {
  43   va_list al;
  44
  45   va_start(al,fmt);
  46   vdebug(ads,fmt,al);
  47   va_end(al);
  48 }
  49
  50 static void vdiag(adns_state ads, const char *fmt, va_list al) {
  51   if (ads->iflags & adns_if_noerrprint) return;
  52   fputs("adns: ",stderr);
  53   vfprintf(stderr,fmt,al);
  54   fputc('\n',stderr);
  55 }
  56
  57 static void diag(adns_state ads, const char *fmt, ...) {
  58   va_list al;
  59
  60   va_start(al,fmt);
  61   vdiag(ads,fmt,al);
  62   va_end(al);
  63 }
  64
  65 static void addserver(adns_state ads, struct in_addr addr) {
  66   int i;
  67   struct server *ss;
  68
  69   for (i=0; i<ads->nservers; i++) {
  70     if (ads->servers[i].addr.s_addr == addr.s_addr) {
  71       debug(ads,"duplicate nameserver %s ignored",inet_ntoa(addr));
  72       return;
  73     }
  74   }
  75
  76   if (ads->nservers>=MAXSERVERS) {
  77     diag(ads,"too many nameservers, ignoring %s",inet_ntoa(addr));
  78     return;
  79   }
  80
  81   ss= ads->servers+ads->nservers;
  82   ss->addr= addr;
  83   ss->state= server_disc;
  84   ss->connw.head= ss->connw.tail= 0;
  85   ads->nservers++;
  86 }
  87
  88 static void configparseerr(adns_state ads, const char *fn, int lno,
  89                            const char *fmt, ...) {
  90   va_list al;
  91
  92   if (ads->iflags & adns_if_noerrprint) return;
  93   if (lno==-1) fprintf(stderr,"adns: %s: ",fn);
  94   else fprintf(stderr,"adns: %s:%d: ",fn,lno);
  95   va_start(al,fmt);
  96   vfprintf(stderr,fmt,al);
  97   va_end(al);
  98   fputc('\n',stderr);
  99 }
 100
 101 static void ccf_nameserver(adns_state ads, const char *fn, int lno, const char *buf) {
 102   struct in_addr ia;
 103
 104   if (!inet_aton(buf,&ia)) {
 105     configparseerr(ads,fn,lno,"invalid nameserver address `%s'",buf);
 106     return;
 107   }
 108   debug(ads,"using nameserver %s",inet_ntoa(ia));
 109   addserver(ads,ia);
 110 }
 111
 112 static void ccf_search(adns_state ads, const char *fn, int lno, const char *buf) {
 113   if (!buf) return;
 114   diag(ads,"warning - `search' ignored FIXME");
 115 }
 116
 117 static void ccf_sortlist(adns_state ads, const char *fn, int lno, const char *buf) {
 118   diag(ads,"warning - `sortlist' ignored FIXME");
 119 }
 120
 121 static void ccf_options(adns_state ads, const char *fn, int lno, const char *buf) {
 122   if (!buf) return;
 123   diag(ads,"warning - `options' ignored FIXME");
 124 }
 125
 126 static void ccf_clearnss(adns_state ads, const char *fn, int lno, const char *buf) {
 127   ads->nservers= 0;
 128 }
 129
 130 static const struct configcommandinfo {
 131   const char *name;
 132   void (*fn)(adns_state ads, const char *fn, int lno, const char *buf);
 133 } configcommandinfos[]= {
 134   { "nameserver",        ccf_nameserver  },
 135   { "domain",            ccf_search      },
 136   { "search",            ccf_search      },
 137   { "sortlist",          ccf_sortlist    },
 138   { "options",           ccf_options     },
 139   { "clearnameservers",  ccf_clearnss    },
 140   {  0                                   }
 141 };
 142
 143 static int ctype_whitespace(int c) { return c==' ' || c=='\n' || c=='\t'; }
 144 static int ctype_digit(int c) { return c>='0' && c<='9'; }
 145
 146 static void readconfig(adns_state ads, const char *filename) {
 147   char linebuf[2000], *p, *q;
 148   FILE *file;
 149   int lno, l, c;
 150   const struct configcommandinfo *ccip;
 151
 152   file= fopen(filename,"r");
 153   if (!file) {
 154     if (errno == ENOENT) {
 155       debug(ads,"configuration file `%s' does not exist",filename);
 156       return;
 157     }
 158     diag(ads,"cannot open configuration file `%s': %s",filename,strerror(errno));
 159     return;
 160   }
 161
 162   for (lno=1; fgets(linebuf,sizeof(linebuf),file); lno++) {
 163     l= strlen(linebuf);
 164     if (!l) continue;
 165     if (linebuf[l-1] != '\n' && !feof(file)) {
 166       diag(ads,"%s:%d: line too long",filename,lno);
 167       while ((c= getc(file)) != EOF && c != '\n') { }
 168       if (c == EOF) break;
 169       continue;
 170     }
 171     while (l>0 && ctype_whitespace(linebuf[l-1])) l--;
 172     linebuf[l]= 0;
 173     p= linebuf;
 174     while (ctype_whitespace(*p)) p++;
 175     if (*p == '#' || *p == '\n') continue;
 176     q= p;
 177     while (*q && !ctype_whitespace(*q)) q++;
 178     for (ccip=configcommandinfos;
 179          ccip->name && strncmp(ccip->name,p,q-p);
 180          ccip++);
 181     if (!ccip->name) {
 182       diag(ads,"%s:%d: unknown configuration directive `%.*s'",filename,lno,q-p,p);
 183       continue;
 184     }
 185     while (ctype_whitespace(*q)) q++;
 186     ccip->fn(ads,filename,lno,q);
 187   }
 188   if (ferror(file)) {
 189     diag(ads,"%s:%d: read error: %s",filename,lno,strerror(errno));
 190   }
 191   fclose(file);
 192 }
 193
 194 static const char *instrum_getenv(adns_state ads, const char *envvar) {
 195   const char *value;
 196
 197   value= getenv(envvar);
 198   if (!value) debug(ads,"environment variable %s not set",envvar);
 199   else debug(ads,"environment variable %s set to `%s'",envvar,value);
 200   return value;
 201 }
 202
 203 static void readconfigenv(adns_state ads, const char *envvar) {
 204   const char *filename;
 205
 206   if (ads->iflags & adns_if_noenv) {
 207     debug(ads,"not checking environment variable `%s'",envvar);
 208     return;
 209   }
 210   filename= instrum_getenv(ads,envvar);
 211   if (filename) readconfig(ads,filename);
 212 }
 213
 214 int adns_init(adns_state *ads_r, adns_initflags flags) {
 215   adns_state ads;
 216   const char *res_options, *adns_res_options;
 217   struct protoent *proto;
 218   int r;
 219
 220   ads= malloc(sizeof(*ads)); if (!ads) return errno;
 221   ads->input.head= ads->input.tail= 0;
 222   ads->timew.head= ads->timew.tail= 0;
 223   ads->childw.head= ads->childw.tail= 0;
 224   ads->output.head= ads->output.tail= 0;
 225   ads->nextid= 0x311f;
 226   ads->udpsocket= -1;
 227   ads->qbufavail= 0;
 228   ads->qbuf= 0;
 229   ads->tcpbufavail= ads->tcpbufused= ads->tcpbufdone= 0;
 230   ads->tcpbuf= 0;
 231   ads->iflags= flags;
 232   ads->nservers= 0;
 233   ads->iflags= flags;
 234
 235   res_options= instrum_getenv(ads,"RES_OPTIONS");
 236   adns_res_options= instrum_getenv(ads,"ADNS_RES_OPTIONS");
 237   ccf_options(ads,"RES_OPTIONS",-1,res_options);
 238   ccf_options(ads,"ADNS_RES_OPTIONS",-1,adns_res_options);
 239
 240   readconfig(ads,"/etc/resolv.conf");
 241   readconfigenv(ads,"RES_CONF");
 242   readconfigenv(ads,"ADNS_RES_CONF");
 243
 244   ccf_options(ads,"RES_OPTIONS",-1,res_options);
 245   ccf_options(ads,"ADNS_RES_OPTIONS",-1,adns_res_options);
 246
 247   ccf_search(ads,"LOCALDOMAIN",-1,instrum_getenv(ads,"LOCALDOMAIN"));
 248   ccf_search(ads,"ADNS_LOCALDOMAIN",-1,instrum_getenv(ads,"ADNS_LOCALDOMAIN"));
 249
 250   if (!ads->nservers) {
 251     struct in_addr ia;
 252     if (ads->iflags & adns_if_debug)
 253       fprintf(stderr,"adns: no nameservers, using localhost\n");
 254     ia.s_addr= INADDR_LOOPBACK;
 255     addserver(ads,ia);
 256   }
 257
 258   proto= getprotobyname("udp"); if (!proto) { r= ENOPROTOOPT; goto x_free; }
 259   ads->udpsocket= socket(AF_INET,SOCK_DGRAM,proto->p_proto);
 260   if (!ads->udpsocket) { r= errno; goto x_closeudp; }
 261
 262   *ads_r= ads;
 263   return 0;
 264
 265  x_closeudp:
 266   close(ads->udpsocket);
 267  x_free:
 268   free(ads);
 269   return r;
 270 }
 271
 272 static void query_fail(adns_state ads, adns_query qu, adns_status stat) {
 273   adns_answer *ans;
 274
 275   ans= qu->answer;
 276   if (!ans) ans= malloc(sizeof(*qu->answer));
 277   if (ans) {
 278     ans->status= stat;
 279     ans->cname= 0;
 280     ans->type= qu->type;
 281     ans->nrrs= 0;
 282   }
 283   qu->answer= ans;
 284   LIST_LINK_TAIL(ads->input,qu);
 285 }
 286
 287 int adns_finish(adns_state ads) {
 288   abort(); /* FIXME */
 289 }
 290
 291 void adns_interest(adns_state ads, int *maxfd,
 292                    fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
 293                    struct timeval **tv_io, struct timeval *tvbuf) {
 294   abort(); /* FIXME */
 295 }
 296
 297 static void autosys(adns_state ads) {
 298   if (ads->iflags & adns_if_noautosys) return;
 299   adns_callback(ads,-1,0,0,0);
 300 }
 301
 302 void adns_cancel(adns_state ads, adns_query query) {
 303   abort(); /* FIXME */
 304 }
 305
 306 int adns_callback(adns_state ads, int maxfd,
 307                   const fd_set *readfds, const fd_set *writefds,
 308                   const fd_set *exceptfds) {
 309   abort(); /* FIXME */
 310 }
 311
 312 static int internal_check(adns_state ads,
 313                           adns_query *query_io,
 314                           adns_answer *answer,
 315                           void *context_r) {
 316   abort(); /* FIXME */
 317 }
 318
 319 int adns_wait(adns_state ads,
 320               adns_query *query_io,
 321               adns_answer *answer,
 322               void *context_r) {
 323   int r, maxfd, rsel, rcb;
 324   fd_set readfds, writefds, exceptfds;
 325   struct timeval tvbuf, *tvp;
 326
 327   for (;;) {
 328     r= internal_check(ads,query_io,answer,context_r);
 329     if (r && r != EWOULDBLOCK) return r;
 330     FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
 331     maxfd= 0; tvp= 0;
 332     adns_interest(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf);
 333     rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
 334     if (rsel==-1) return r;
 335     rcb= adns_callback(ads,maxfd,&readfds,&writefds,&exceptfds);
 336     assert(rcb==rsel);
 337   }
 338 }
 339
 340 int adns_check(adns_state ads,
 341                adns_query *query_io,
 342                adns_answer *answer,
 343                void *context_r) {
 344   autosys(ads);
 345   return internal_check(ads,query_io,answer,context_r);
 346 }
 347
 348 int adns_synchronous(adns_state ads,
 349                      const char *owner,
 350                      adns_rrtype type,
 351                      adns_queryflags flags,
 352                      adns_answer *answer) {
 353   adns_query qu;
 354   int r;
 355
 356   r= adns_submit(ads,owner,type,flags,0,&qu);
 357   if (r) return r;
 358
 359   do {
 360     r= adns_wait(ads,&qu,answer,0);
 361   } while (r==EINTR);
 362   if (r) adns_cancel(ads,qu);
 363   return r;
 364 }
 365
 366 static adns_status mkquery(adns_state ads, const char *owner, int ol, int id,
 367                            adns_rrtype type, adns_queryflags flags, int *qml_r) {
 368   int ll, c, nlabs, qbufreq;
 369   unsigned char label[255], *nqbuf;
 370   const char *p, *pe;
 371
 372 #define MKQUERY_ADDB(b) *nqbuf++= (b)
 373 #define MKQUERY_ADDW(w) (MKQUERY_ADDB(((w)>>8)&0x0ff), MKQUERY_ADDB((w)&0x0ff))
 374
 375   qbufreq= 12+strlen(owner)+3;
 376   if (ads->qbufavail < qbufreq) {
 377     nqbuf= realloc(ads->qbuf,qbufreq);
 378     if (!nqbuf) return adns_s_nolocalmem;
 379     ads->qbuf= nqbuf; ads->qbufavail= qbufreq;
 380   }
 381   nqbuf= ads->qbuf;
 382
 383   MKQUERY_ADDW(id);
 384   MKQUERY_ADDB(0x01); /* QR=Q(0), OPCODE=QUERY(0000), !AA, !TC, RD */
 385   MKQUERY_ADDB(0x00); /* !RA, Z=000, RCODE=NOERROR(0000) */
 386   MKQUERY_ADDW(1); /* QDCOUNT=1 */
 387   MKQUERY_ADDW(0); /* ANCOUNT=0 */
 388   MKQUERY_ADDW(0); /* NSCOUNT=0 */
 389   MKQUERY_ADDW(0); /* ARCOUNT=0 */
 390   p= owner; pe= owner+ol;
 391   nlabs= 0;
 392   if (!*p) return adns_s_invaliddomain;
 393   do {
 394     ll= 0;
 395     while (p!=pe && (c= *p++)!='.') {
 396       if (c=='\\') {
 397         if (!(flags & adns_f_anyquote)) return adns_s_invaliddomain;
 398         if (ctype_digit(p[0])) {
 399           if (ctype_digit(p[1]) && ctype_digit(p[2])) {
 400             c= (*p++ - '0')*100 + (*p++ - '0')*10 + (*p++ - '0');
 401             if (c >= 256) return adns_s_invaliddomain;
 402           } else {
 403             return adns_s_invaliddomain;
 404           }
 405         } else if (!(c= *p++)) {
 406           return adns_s_invaliddomain;
 407         }
 408       }
 409       if (!(flags & adns_f_anyquote)) {
 410         if ((c >= '0' && c <= '9') || c == '-') {
 411           if (!ll) return adns_s_invaliddomain;
 412         } else if ((c < 'a' || c > 'z') && (c < 'A' && c > 'Z')) {
 413           return adns_s_invaliddomain;
 414         }
 415       }
 416       if (ll == sizeof(label)) return adns_s_invaliddomain;
 417       label[ll++]= c;
 418     }
 419     if (!ll) return adns_s_invaliddomain;
 420     if (nlabs++ > 63) return adns_s_invaliddomain;
 421     MKQUERY_ADDB(ll);
 422     memcpy(nqbuf,label,ll); nqbuf+= ll;
 423   } while (p!=pe);
 424
 425   MKQUERY_ADDB(0);
 426   MKQUERY_ADDW(type & adns__rrt_typemask); /* QTYPE */
 427   MKQUERY_ADDW(1); /* QCLASS=IN */
 428
 429   *qml_r= nqbuf - ads->qbuf;
 430
 431   return adns_s_ok;
 432 }
 433
 434 static adns_query allocquery(adns_state ads, const char *owner, int ol,
 435                              int qml, int id, adns_rrtype type,
 436                              adns_queryflags flags, void *context) {
 437   adns_query qu;
 438   unsigned char *qm;
 439
 440   qu= malloc(sizeof(*qu)+ol+1+qml); if (!qu) return 0;
 441   qu->next= qu->back= qu->parent= qu->child= 0;
 442   qu->id= id;
 443   qu->type= type;
 444   qu->answer= 0;
 445   qu->flags= flags;
 446   qu->context= context;
 447   qu->udpretries= 0;
 448   qu->sentudp= qu->senttcp= 0;
 449   qu->nextserver= 0;
 450   memcpy(qu->owner,owner,ol); qu->owner[ol]= 0;
 451   qu->querymsg= qm= qu->owner+ol+1;
 452   memcpy(qm,ads->qbuf,qml);
 453   qu->querylen= qml;
 454   return qu;
 455 }
 456
 457 static int failsubmit(adns_state ads, void *context, adns_query *query_r,
 458                       adns_rrtype type, adns_queryflags flags,
 459                       int id, adns_status stat) {
 460   adns_query qu;
 461
 462   qu= allocquery(ads,0,0,0,id,type,flags,context); if (!qu) return errno;
 463   query_fail(ads,qu,stat);
 464   *query_r= qu;
 465   return 0;
 466 }
 467
 468 int adns_submit(adns_state ads,
 469                 const char *owner,
 470                 adns_rrtype type,
 471                 adns_queryflags flags,
 472                 void *context,
 473                 adns_query *query_r) {
 474   adns_query qu;
 475   adns_status stat;
 476   int ol, id, qml;
 477
 478   id= ads->nextid++;
 479
 480   ol= strlen(owner);
 481   if (ol<=1 || ol>MAXDNAME+1)
 482     return failsubmit(ads,context,query_r,type,flags,id,adns_s_invaliddomain);
 483   if (owner[ol-1]=='.' && owner[ol-2]!='\\') { flags &= ~adns_f_search; ol--; }
 484
 485   stat= mkquery(ads,owner,ol,id,type,flags,&qml);
 486   if (stat) return failsubmit(ads,context,query_r,type,flags,id,stat);
 487
 488   qu= allocquery(ads,owner,ol,qml,id,type,flags,context); if (!qu) return errno;
 489
 490   LIST_LINK_TAIL(ads->input,qu);
 491   autosys(ads);
 492
 493   *query_r= qu;
 494   return 0;
 495 }