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

   1 /*
   2  * setup.c
   3  * - configuration file parsing
   4  * - management of global state
   5  */
   6 /*
   7  *  This file is
   8  *    Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk>
   9  *
  10  *  It is part of adns, which is
  11  *    Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
  12  *    Copyright (C) 1999-2000 Tony Finch <dot@dotat.at>
  13  *
  14  *  This program is free software; you can redistribute it and/or modify
  15  *  it under the terms of the GNU General Public License as published by
  16  *  the Free Software Foundation; either version 2, or (at your option)
  17  *  any later version.
  18  *
  19  *  This program is distributed in the hope that it will be useful,
  20  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  *  GNU General Public License for more details.
  23  *
  24  *  You should have received a copy of the GNU General Public License
  25  *  along with this program; if not, write to the Free Software Foundation,
  26  *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 #include <stdlib.h>
  30 #include <errno.h>
  31 #include <limits.h>
  32 #include <unistd.h>
  33 #include <fcntl.h>
  34
  35 #include <netdb.h>
  36 #include <sys/socket.h>
  37 #include <netinet/in.h>
  38 #include <arpa/inet.h>
  39
  40 #include "internal.h"
  41
  42 static void readconfig(adns_state ads, const char *filename, int warnmissing);
  43
  44 static void addserver(adns_state ads, struct in_addr addr) {
  45   int i;
  46   struct server *ss;
  47
  48   for (i=0; i<ads->nservers; i++) {
  49     if (ads->servers[i].addr.s_addr == addr.s_addr) {
  50       adns__debug(ads,-1,0,"duplicate nameserver %s ignored",inet_ntoa(addr));
  51       return;
  52     }
  53   }
  54
  55   if (ads->nservers>=MAXSERVERS) {
  56     adns__diag(ads,-1,0,"too many nameservers, ignoring %s",inet_ntoa(addr));
  57     return;
  58   }
  59
  60   ss= ads->servers+ads->nservers;
  61   ss->addr= addr;
  62   ads->nservers++;
  63 }
  64
  65 static void freesearchlist(adns_state ads) {
  66   if (ads->nsearchlist) free(*ads->searchlist);
  67   free(ads->searchlist);
  68 }
  69
  70 static void saveerr(adns_state ads, int en) {
  71   if (!ads->configerrno) ads->configerrno= en;
  72 }
  73
  74 static void configparseerr(adns_state ads, const char *fn, int lno,
  75                            const char *fmt, ...) {
  76   va_list al;
  77
  78   saveerr(ads,EINVAL);
  79   if (!ads->diagfile || (ads->iflags & adns_if_noerrprint)) return;
  80
  81   if (lno==-1) fprintf(ads->diagfile,"adns: %s: ",fn);
  82   else fprintf(ads->diagfile,"adns: %s:%d: ",fn,lno);
  83   va_start(al,fmt);
  84   vfprintf(ads->diagfile,fmt,al);
  85   va_end(al);
  86   fputc('\n',ads->diagfile);
  87 }
  88
  89 static int nextword(const char **bufp_io, const char **word_r, int *l_r) {
  90   const char *p, *q;
  91
  92   p= *bufp_io;
  93   while (ctype_whitespace(*p)) p++;
  94   if (!*p) return 0;
  95
  96   q= p;
  97   while (*q && !ctype_whitespace(*q)) q++;
  98
  99   *l_r= q-p;
 100   *word_r= p;
 101   *bufp_io= q;
 102
 103   return 1;
 104 }
 105
 106 static void ccf_nameserver(adns_state ads, const char *fn, int lno, const char *buf) {
 107   struct in_addr ia;
 108
 109   if (!inet_aton(buf,&ia)) {
 110     configparseerr(ads,fn,lno,"invalid nameserver address `%s'",buf);
 111     return;
 112   }
 113   adns__debug(ads,-1,0,"using nameserver %s",inet_ntoa(ia));
 114   addserver(ads,ia);
 115 }
 116
 117 static void ccf_search(adns_state ads, const char *fn, int lno, const char *buf) {
 118   const char *bufp, *word;
 119   char *newchars, **newptrs, **pp;
 120   int count, tl, l;
 121
 122   if (!buf) return;
 123
 124   bufp= buf;
 125   count= 0;
 126   tl= 0;
 127   while (nextword(&bufp,&word,&l)) { count++; tl += l+1; }
 128
 129   newptrs= malloc(sizeof(char*)*count);  if (!newptrs) { saveerr(ads,errno); return; }
 130   newchars= malloc(tl);  if (!newchars) { saveerr(ads,errno); free(newptrs); return; }
 131
 132   bufp= buf;
 133   pp= newptrs;
 134   while (nextword(&bufp,&word,&l)) {
 135     *pp++= newchars;
 136     memcpy(newchars,word,l);
 137     newchars += l;
 138     *newchars++ = 0;
 139   }
 140
 141   freesearchlist(ads);
 142   ads->nsearchlist= count;
 143   ads->searchlist= newptrs;
 144 }
 145
 146 static void ccf_sortlist(adns_state ads, const char *fn, int lno, const char *buf) {
 147   const char *word;
 148   char tbuf[200], *slash, *ep;
 149   struct in_addr base, mask;
 150   int l;
 151   unsigned long initial, baselocal;
 152
 153   if (!buf) return;
 154
 155   ads->nsortlist= 0;
 156   while (nextword(&buf,&word,&l)) {
 157     if (ads->nsortlist >= MAXSORTLIST) {
 158       adns__diag(ads,-1,0,"too many sortlist entries, ignoring %.*s onwards",l,word);
 159       return;
 160     }
 161
 162     if (l >= sizeof(tbuf)) {
 163       configparseerr(ads,fn,lno,"sortlist entry `%.*s' too long",l,word);
 164       continue;
 165     }
 166
 167     memcpy(tbuf,word,l); tbuf[l]= 0;
 168     slash= strchr(tbuf,'/');
 169     if (slash) *slash++= 0;
 170
 171     if (!inet_aton(tbuf,&base)) {
 172       configparseerr(ads,fn,lno,"invalid address `%s' in sortlist",tbuf);
 173       continue;
 174     }
 175
 176     if (slash) {
 177       if (strchr(slash,'.')) {
 178         if (!inet_aton(slash,&mask)) {
 179           configparseerr(ads,fn,lno,"invalid mask `%s' in sortlist",slash);
 180           continue;
 181         }
 182         if (base.s_addr & ~mask.s_addr) {
 183           configparseerr(ads,fn,lno,
 184                          "mask `%s' in sortlist overlaps address `%s'",slash,tbuf);
 185           continue;
 186         }
 187       } else {
 188         initial= strtoul(slash,&ep,10);
 189         if (*ep || initial>32) {
 190           configparseerr(ads,fn,lno,"mask length `%s' invalid",slash);
 191           continue;
 192         }
 193         mask.s_addr= htonl((0x0ffffffffUL) << (32-initial));
 194       }
 195     } else {
 196       baselocal= ntohl(base.s_addr);
 197       if (!baselocal & 0x080000000UL) /* class A */
 198         mask.s_addr= htonl(0x0ff000000UL);
 199       else if ((baselocal & 0x0c0000000UL) == 0x080000000UL)
 200         mask.s_addr= htonl(0x0ffff0000UL); /* class B */
 201       else if ((baselocal & 0x0f0000000UL) == 0x0e0000000UL)
 202         mask.s_addr= htonl(0x0ff000000UL); /* class C */
 203       else {
 204         configparseerr(ads,fn,lno,
 205                        "network address `%s' in sortlist is not in classed ranges,"
 206                        " must specify mask explicitly", tbuf);
 207         continue;
 208       }
 209     }
 210
 211     ads->sortlist[ads->nsortlist].base= base;
 212     ads->sortlist[ads->nsortlist].mask= mask;
 213     ads->nsortlist++;
 214   }
 215 }
 216
 217 static void ccf_options(adns_state ads, const char *fn, int lno, const char *buf) {
 218   const char *word;
 219   char *ep;
 220   unsigned long v;
 221   int l;
 222
 223   if (!buf) return;
 224
 225   while (nextword(&buf,&word,&l)) {
 226     if (l==5 && !memcmp(word,"debug",5)) {
 227       ads->iflags |= adns_if_debug;
 228       continue;
 229     }
 230     if (l>=6 && !memcmp(word,"ndots:",6)) {
 231       v= strtoul(word+6,&ep,10);
 232       if (l==6 || ep != word+l || v > INT_MAX) {
 233         configparseerr(ads,fn,lno,"option `%.*s' malformed or has bad value",l,word);
 234         continue;
 235       }
 236       ads->searchndots= v;
 237       continue;
 238     }
 239     if (l>=12 && !memcmp(word,"adns_checkc:",12)) {
 240       if (!strcmp(word+12,"none")) {
 241         ads->iflags &= ~adns_if_checkc_freq;
 242         ads->iflags |= adns_if_checkc_entex;
 243       } else if (!strcmp(word+12,"entex")) {
 244         ads->iflags &= ~adns_if_checkc_freq;
 245         ads->iflags |= adns_if_checkc_entex;
 246       } else if (!strcmp(word+12,"freq")) {
 247         ads->iflags |= adns_if_checkc_freq;
 248       } else {
 249         configparseerr(ads,fn,lno, "option adns_checkc has bad value `%s' "
 250                        "(must be none, entex or freq", word+12);
 251       }
 252       continue;
 253     }
 254     adns__diag(ads,-1,0,"%s:%d: unknown option `%.*s'", fn,lno, l,word);
 255   }
 256 }
 257
 258 static void ccf_clearnss(adns_state ads, const char *fn, int lno, const char *buf) {
 259   ads->nservers= 0;
 260 }
 261
 262 static void ccf_include(adns_state ads, const char *fn, int lno, const char *buf) {
 263   if (!*buf) {
 264     configparseerr(ads,fn,lno,"`include' directive with no filename");
 265     return;
 266   }
 267   readconfig(ads,buf,1);
 268 }
 269
 270 static void ccf_lookup(adns_state ads, const char *fn, int lno,
 271                        const char *buf) {
 272   int found_bind=0;
 273   const char *word;
 274   int l;
 275
 276   if (!*buf) {
 277     configparseerr(ads,fn,lno,"`lookup' directive with no databases");
 278     return;
 279   }
 280
 281   while (nextword(&buf,&word,&l)) {
 282     if (l==4 && !memcmp(word,"bind",4)) {
 283       found_bind=1;
 284     } else if (l==4 && !memcmp(word,"file",4)) {
 285       /* ignore this and hope /etc/hosts is not essential */
 286     } else if (l==2 && !memcmp(word,"yp",2)) {
 287       adns__diag(ads,-1,0,"%s:%d: yp lookups not supported by adns", fn,lno);
 288       found_bind=-1;
 289     } else {
 290       adns__diag(ads,-1,0,"%s:%d: unknown `lookup' database `%.*s'",
 291                  fn,lno, l,word);
 292       found_bind=-1;
 293     }
 294   }
 295   if (!found_bind)
 296     adns__diag(ads,-1,0,"%s:%d: `lookup' specified, but not `bind'", fn,lno);
 297 }
 298
 299 static const struct configcommandinfo {
 300   const char *name;
 301   void (*fn)(adns_state ads, const char *fn, int lno, const char *buf);
 302 } configcommandinfos[]= {
 303   { "nameserver",        ccf_nameserver  },
 304   { "domain",            ccf_search      },
 305   { "search",            ccf_search      },
 306   { "sortlist",          ccf_sortlist    },
 307   { "options",           ccf_options     },
 308   { "clearnameservers",  ccf_clearnss    },
 309   { "include",           ccf_include     },
 310   { "lookup",            ccf_lookup      }, /* OpenBSD */
 311   {  0                                   }
 312 };
 313
 314 typedef union {
 315   FILE *file;
 316   const char *text;
 317 } getline_ctx;
 318
 319 static int gl_file(adns_state ads, getline_ctx *src_io, const char *filename,
 320                    int lno, char *buf, int buflen) {
 321   FILE *file= src_io->file;
 322   int c, i;
 323   char *p;
 324
 325   p= buf;
 326   buflen--;
 327   i= 0;
 328
 329   for (;;) { /* loop over chars */
 330     if (i == buflen) {
 331       adns__diag(ads,-1,0,"%s:%d: line too long, ignored",filename,lno);
 332       goto x_badline;
 333     }
 334     c= getc(file);
 335     if (!c) {
 336       adns__diag(ads,-1,0,"%s:%d: line contains nul, ignored",filename,lno);
 337       goto x_badline;
 338     } else if (c == '\n') {
 339       break;
 340     } else if (c == EOF) {
 341       if (ferror(file)) {
 342         saveerr(ads,errno);
 343         adns__diag(ads,-1,0,"%s:%d: read error: %s",filename,lno,strerror(errno));
 344         return -1;
 345       }
 346       if (!i) return -1;
 347       break;
 348     } else {
 349       *p++= c;
 350       i++;
 351     }
 352   }
 353
 354   *p++= 0;
 355   return i;
 356
 357  x_badline:
 358   saveerr(ads,EINVAL);
 359   while ((c= getc(file)) != EOF && c != '\n');
 360   return -2;
 361 }
 362
 363 static int gl_text(adns_state ads, getline_ctx *src_io, const char *filename,
 364                    int lno, char *buf, int buflen) {
 365   const char *cp= src_io->text;
 366   int l;
 367
 368   if (!cp || !*cp) return -1;
 369
 370   if (*cp == ';' || *cp == '\n') cp++;
 371   l= strcspn(cp,";\n");
 372   src_io->text = cp+l;
 373
 374   if (l >= buflen) {
 375     adns__diag(ads,-1,0,"%s:%d: line too long, ignored",filename,lno);
 376     saveerr(ads,EINVAL);
 377     return -2;
 378   }
 379
 380   memcpy(buf,cp,l);
 381   buf[l]= 0;
 382   return l;
 383 }
 384
 385 static void readconfiggeneric(adns_state ads, const char *filename,
 386                               int (*getline)(adns_state ads, getline_ctx*,
 387                                              const char *filename, int lno,
 388                                              char *buf, int buflen),
 389                               /* Returns >=0 for success, -1 for EOF or error
 390                                * (error will have been reported), or -2 for
 391                                * bad line was encountered, try again.
 392                                */
 393                               getline_ctx gl_ctx) {
 394   char linebuf[2000], *p, *q;
 395   int lno, l, dirl;
 396   const struct configcommandinfo *ccip;
 397
 398   for (lno=1;
 399        (l= getline(ads,&gl_ctx, filename,lno, linebuf,sizeof(linebuf))) != -1;
 400        lno++) {
 401     if (l == -2) continue;
 402     while (l>0 && ctype_whitespace(linebuf[l-1])) l--;
 403     linebuf[l]= 0;
 404     p= linebuf;
 405     while (ctype_whitespace(*p)) p++;
 406     if (*p == '#' || !*p) continue;
 407     q= p;
 408     while (*q && !ctype_whitespace(*q)) q++;
 409     dirl= q-p;
 410     for (ccip=configcommandinfos;
 411          ccip->name && !(strlen(ccip->name)==dirl && !memcmp(ccip->name,p,q-p));
 412          ccip++);
 413     if (!ccip->name) {
 414       adns__diag(ads,-1,0,"%s:%d: unknown configuration directive `%.*s'",
 415                  filename,lno,q-p,p);
 416       continue;
 417     }
 418     while (ctype_whitespace(*q)) q++;
 419     ccip->fn(ads,filename,lno,q);
 420   }
 421 }
 422
 423 static const char *instrum_getenv(adns_state ads, const char *envvar) {
 424   const char *value;
 425
 426   value= getenv(envvar);
 427   if (!value) adns__debug(ads,-1,0,"environment variable %s not set",envvar);
 428   else adns__debug(ads,-1,0,"environment variable %s set to `%s'",envvar,value);
 429   return value;
 430 }
 431
 432 static void readconfig(adns_state ads, const char *filename, int warnmissing) {
 433   getline_ctx gl_ctx;
 434
 435   gl_ctx.file= fopen(filename,"r");
 436   if (!gl_ctx.file) {
 437     if (errno == ENOENT) {
 438       if (warnmissing)
 439         adns__debug(ads,-1,0,"configuration file `%s' does not exist",filename);
 440       return;
 441     }
 442     saveerr(ads,errno);
 443     adns__diag(ads,-1,0,"cannot open configuration file `%s': %s",
 444                filename,strerror(errno));
 445     return;
 446   }
 447
 448   readconfiggeneric(ads,filename,gl_file,gl_ctx);
 449
 450   fclose(gl_ctx.file);
 451 }
 452
 453 static void readconfigtext(adns_state ads, const char *text, const char *showname) {
 454   getline_ctx gl_ctx;
 455
 456   gl_ctx.text= text;
 457   readconfiggeneric(ads,showname,gl_text,gl_ctx);
 458 }
 459
 460 static void readconfigenv(adns_state ads, const char *envvar) {
 461   const char *filename;
 462
 463   if (ads->iflags & adns_if_noenv) {
 464     adns__debug(ads,-1,0,"not checking environment variable `%s'",envvar);
 465     return;
 466   }
 467   filename= instrum_getenv(ads,envvar);
 468   if (filename) readconfig(ads,filename,1);
 469 }
 470
 471 static void readconfigenvtext(adns_state ads, const char *envvar) {
 472   const char *textdata;
 473
 474   if (ads->iflags & adns_if_noenv) {
 475     adns__debug(ads,-1,0,"not checking environment variable `%s'",envvar);
 476     return;
 477   }
 478   textdata= instrum_getenv(ads,envvar);
 479   if (textdata) readconfigtext(ads,textdata,envvar);
 480 }
 481
 482
 483 int adns__setnonblock(adns_state ads, int fd) {
 484   int r;
 485
 486   r= fcntl(fd,F_GETFL,0); if (r<0) return errno;
 487   r |= O_NONBLOCK;
 488   r= fcntl(fd,F_SETFL,r); if (r<0) return errno;
 489   return 0;
 490 }
 491
 492 static int init_begin(adns_state *ads_r, adns_initflags flags, FILE *diagfile) {
 493   adns_state ads;
 494
 495   ads= malloc(sizeof(*ads)); if (!ads) return errno;
 496
 497   ads->iflags= flags;
 498   ads->diagfile= diagfile;
 499   ads->configerrno= 0;
 500   LIST_INIT(ads->udpw);
 501   LIST_INIT(ads->tcpw);
 502   LIST_INIT(ads->childw);
 503   LIST_INIT(ads->output);
 504   ads->forallnext= 0;
 505   ads->nextid= 0x311f;
 506   ads->udpsocket= ads->tcpsocket= -1;
 507   adns__vbuf_init(&ads->tcpsend);
 508   adns__vbuf_init(&ads->tcprecv);
 509   ads->tcprecv_skip= 0;
 510   ads->nservers= ads->nsortlist= ads->nsearchlist= ads->tcpserver= 0;
 511   ads->searchndots= 1;
 512   ads->tcpstate= server_disconnected;
 513   timerclear(&ads->tcptimeout);
 514   ads->searchlist= 0;
 515
 516   *ads_r= ads;
 517   return 0;
 518 }
 519
 520 static int init_finish(adns_state ads) {
 521   struct in_addr ia;
 522   struct protoent *proto;
 523   int r;
 524
 525   if (!ads->nservers) {
 526     if (ads->diagfile && ads->iflags & adns_if_debug)
 527       fprintf(ads->diagfile,"adns: no nameservers, using localhost\n");
 528     ia.s_addr= htonl(INADDR_LOOPBACK);
 529     addserver(ads,ia);
 530   }
 531
 532   proto= getprotobyname("udp"); if (!proto) { r= ENOPROTOOPT; goto x_free; }
 533   ads->udpsocket= socket(AF_INET,SOCK_DGRAM,proto->p_proto);
 534   if (ads->udpsocket<0) { r= errno; goto x_free; }
 535
 536   r= adns__setnonblock(ads,ads->udpsocket);
 537   if (r) { r= errno; goto x_closeudp; }
 538
 539   return 0;
 540
 541  x_closeudp:
 542   close(ads->udpsocket);
 543  x_free:
 544   free(ads);
 545   return r;
 546 }
 547
 548 static void init_abort(adns_state ads) {
 549   if (ads->nsearchlist) {
 550     free(ads->searchlist[0]);
 551     free(ads->searchlist);
 552   }
 553   free(ads);
 554 }
 555
 556 int adns_init(adns_state *ads_r, adns_initflags flags, FILE *diagfile) {
 557   adns_state ads;
 558   const char *res_options, *adns_res_options;
 559   int r;
 560
 561   r= init_begin(&ads, flags, diagfile ? diagfile : stderr);
 562   if (r) return r;
 563
 564   res_options= instrum_getenv(ads,"RES_OPTIONS");
 565   adns_res_options= instrum_getenv(ads,"ADNS_RES_OPTIONS");
 566   ccf_options(ads,"RES_OPTIONS",-1,res_options);
 567   ccf_options(ads,"ADNS_RES_OPTIONS",-1,adns_res_options);
 568
 569   readconfig(ads,"/etc/resolv.conf",1);
 570   readconfig(ads,"/etc/resolv-adns.conf",0);
 571   readconfigenv(ads,"RES_CONF");
 572   readconfigenv(ads,"ADNS_RES_CONF");
 573
 574   readconfigenvtext(ads,"RES_CONF_TEXT");
 575   readconfigenvtext(ads,"ADNS_RES_CONF_TEXT");
 576
 577   ccf_options(ads,"RES_OPTIONS",-1,res_options);
 578   ccf_options(ads,"ADNS_RES_OPTIONS",-1,adns_res_options);
 579
 580   ccf_search(ads,"LOCALDOMAIN",-1,instrum_getenv(ads,"LOCALDOMAIN"));
 581   ccf_search(ads,"ADNS_LOCALDOMAIN",-1,instrum_getenv(ads,"ADNS_LOCALDOMAIN"));
 582
 583   if (ads->configerrno && ads->configerrno != EINVAL) {
 584     r= ads->configerrno;
 585     init_abort(ads);
 586     return r;
 587   }
 588
 589   r= init_finish(ads);
 590   if (r) return r;
 591
 592   adns__consistency(ads,0,cc_entex);
 593   *ads_r= ads;
 594   return 0;
 595 }
 596
 597 int adns_init_strcfg(adns_state *ads_r, adns_initflags flags,
 598                      FILE *diagfile, const char *configtext) {
 599   adns_state ads;
 600   int r;
 601
 602   r= init_begin(&ads, flags, diagfile);  if (r) return r;
 603
 604   readconfigtext(ads,configtext,"<supplied configuration text>");
 605   if (ads->configerrno) {
 606     r= ads->configerrno;
 607     init_abort(ads);
 608     return r;
 609   }
 610
 611   r= init_finish(ads);  if (r) return r;
 612   adns__consistency(ads,0,cc_entex);
 613   *ads_r= ads;
 614   return 0;
 615 }
 616
 617
 618 void adns_finish(adns_state ads) {
 619   adns__consistency(ads,0,cc_entex);
 620   for (;;) {
 621     if (ads->udpw.head) adns_cancel(ads->udpw.head);
 622     else if (ads->tcpw.head) adns_cancel(ads->tcpw.head);
 623     else if (ads->childw.head) adns_cancel(ads->childw.head);
 624     else if (ads->output.head) adns_cancel(ads->output.head);
 625     else break;
 626   }
 627   close(ads->udpsocket);
 628   if (ads->tcpsocket >= 0) close(ads->tcpsocket);
 629   adns__vbuf_free(&ads->tcpsend);
 630   adns__vbuf_free(&ads->tcprecv);
 631   freesearchlist(ads);
 632   free(ads);
 633 }
 634
 635 void adns_forallqueries_begin(adns_state ads) {
 636   adns__consistency(ads,0,cc_entex);
 637   ads->forallnext=
 638     ads->udpw.head ? ads->udpw.head :
 639     ads->tcpw.head ? ads->tcpw.head :
 640     ads->childw.head ? ads->childw.head :
 641     ads->output.head;
 642 }
 643
 644 adns_query adns_forallqueries_next(adns_state ads, void **context_r) {
 645   adns_query qu, nqu;
 646
 647   adns__consistency(ads,0,cc_entex);
 648   nqu= ads->forallnext;
 649   for (;;) {
 650     qu= nqu;
 651     if (!qu) return 0;
 652     if (qu->next) {
 653       nqu= qu->next;
 654     } else if (qu == ads->udpw.tail) {
 655       nqu=
 656         ads->tcpw.head ? ads->tcpw.head :
 657         ads->childw.head ? ads->childw.head :
 658         ads->output.head;
 659     } else if (qu == ads->tcpw.tail) {
 660       nqu=
 661         ads->childw.head ? ads->childw.head :
 662         ads->output.head;
 663     } else if (qu == ads->childw.tail) {
 664       nqu= ads->output.head;
 665     } else {
 666       nqu= 0;
 667     }
 668     if (!qu->parent) break;
 669   }
 670   ads->forallnext= nqu;
 671   if (context_r) *context_r= qu->ctx.ext;
 672   return qu;
 673 }