[adns] / src / types.c

/*
 * types.c
 * - RR-type-specific code, and the machinery to call it
 */
/*
 *  This file is part of adns, which is
 *    Copyright (C) 1997-2000,2003,2006  Ian Jackson
 *    Copyright (C) 1999-2000,2003,2006  Tony Finch
 *    Copyright (C) 1991 Massachusetts Institute of Technology
 *  (See the file INSTALL for full details.)
 *  
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *  
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software Foundation,
 *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 
 */

#include <stdlib.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "internal.h"

#define R_NOMEM       return adns_s_nomemory
#define CSP_ADDSTR(s) do {                      \
    if (!adns__vbuf_appendstr(vb,(s))) R_NOMEM; \
  } while (0)

/*
 * order of sections:
 *
 * _string                    (pap)
 * _textdata, _qstring        (csp)
 * _str                       (mf,cs)
 * _intstr                    (mf,csp,cs)
 * _manyistr                  (mf,cs)
 * _txt                       (pa)
 * _inaddr                    (pa,dip,di,cs +search_sortlist)
 * _addr                      (pa,di,div,csp,cs,gsz)
 * _domain                    (pap,csp,cs)
 * _dom_raw                   (pa)
 * _host_raw                  (pa)
 * _hostaddr                  (pap,pa,dip,di,mfp,mf,csp,cs
 *                              +pap_findaddrs, icb_hostaddr)
 * _mx_raw                    (pa,di)
 * _mx                        (pa,di)
 * _inthostaddr               (mf,cs)
 * _inthost                   (cs)
 * _ptr                       (ckl,pa +icb_ptr)
 * _strpair                   (mf)
 * _intstrpair                (mf)
 * _hinfo                     (pa)
 * _mailbox                   (pap,csp +pap_mailbox822)
 * _rp                        (pa,cs)
 * _soa                       (pa,mf,cs)
 * _srv*                      (ckl,(pap),pa*2,mf*2,di,(csp),cs*2,postsort)
 * _byteblock                 (mf)
 * _opaque                    (pa,cs)
 * _flat                      (mf)
 *
 * within each section:
 *    ckl_*
 *    pap_*
 *    pa_*
 *    dip_*
 *    di_*
 *    mfp_*
 *    mf_*
 *    csp_*
 *    cs_*
 *    gsz_*
 *    postsort_*
 */

/*
 * _qstring               (pap,csp)
 */

static adns_status pap_qstring(const parseinfo *pai, int *cbyte_io, int max,
                              int *len_r, char **str_r) {
  /* Neither len_r nor str_r may be null.
   * End of datagram (overrun) is indicated by returning adns_s_invaliddata;
   */
  const byte *dgram= pai->dgram;
  int l, cbyte;
  char *str;

  cbyte= *cbyte_io;

  if (cbyte >= max) return adns_s_invaliddata;
  GET_B(cbyte,l);
  if (cbyte+l > max) return adns_s_invaliddata;
  
  str= adns__alloc_interim(pai->qu, l+1);
  if (!str) R_NOMEM;
  
  str[l]= 0;
  memcpy(str,dgram+cbyte,l);

  *len_r= l;
  *str_r= str;
  *cbyte_io= cbyte+l;
  
  return adns_s_ok;
}

static adns_status csp_qstring(vbuf *vb, const char *dp, int len) {
  unsigned char ch;
  char buf[10];
  int cn;

  CSP_ADDSTR("\"");
  for (cn=0; cn<len; cn++) {
    ch= *dp++;
    if (ch == '\\') {
      CSP_ADDSTR("\\\\");
    } else if (ch == '"') {
      CSP_ADDSTR("\\\"");
    } else if (ch >= 32 && ch <= 126) {
      if (!adns__vbuf_append(vb,&ch,1)) R_NOMEM;
    } else {
      sprintf(buf,"\\x%02x",ch);
      CSP_ADDSTR(buf);
    }
  }
  CSP_ADDSTR("\"");
  
  return adns_s_ok;
}

/*
 * _str  (mf)
 */

static void mf_str(adns_query qu, void *datap) {
  char **rrp= datap;

  adns__makefinal_str(qu,rrp);
}

/*
 * _intstr  (mf)
 */

static void mf_intstr(adns_query qu, void *datap) {
  adns_rr_intstr *rrp= datap;

  adns__makefinal_str(qu,&rrp->str);
}

/*
 * _manyistr   (mf)
 */

static void mf_manyistr(adns_query qu, void *datap) {
  adns_rr_intstr **rrp= datap;
  adns_rr_intstr *te, *table;
  void *tablev;
  int tc;

  for (tc=0, te= *rrp; te->i >= 0; te++, tc++);
  tablev= *rrp;
  adns__makefinal_block(qu,&tablev,sizeof(*te)*(tc+1));
  *rrp= table= tablev;
  for (te= *rrp; te->i >= 0; te++)
    adns__makefinal_str(qu,&te->str);
}

/*
 * _txt   (pa,cs)
 */

static adns_status pa_txt(const parseinfo *pai, int cbyte,
                          int max, void *datap) {
  adns_rr_intstr **rrp= datap, *table, *te;
  const byte *dgram= pai->dgram;
  int ti, tc, l, startbyte;
  adns_status st;

  startbyte= cbyte;
  if (cbyte >= max) return adns_s_invaliddata;
  tc= 0;
  while (cbyte < max) {
    GET_B(cbyte,l);
    cbyte+= l;
    tc++;
  }
  if (cbyte != max || !tc) return adns_s_invaliddata;

  table= adns__alloc_interim(pai->qu,sizeof(*table)*(tc+1));
  if (!table) R_NOMEM;

  for (cbyte=startbyte, ti=0, te=table; ti<tc; ti++, te++) {
    st= pap_qstring(pai, &cbyte, max, &te->i, &te->str);
    if (st) return st;
  }
  assert(cbyte == max);

  te->i= -1;
  te->str= 0;
  
  *rrp= table;
  return adns_s_ok;
}

static adns_status cs_txt(vbuf *vb, const void *datap) {
  const adns_rr_intstr *const *rrp= datap;
  const adns_rr_intstr *current;
  adns_status st;
  int spc;

  for (current= *rrp, spc=0;  current->i >= 0;  current++, spc=1) {
    if (spc) CSP_ADDSTR(" ");
    st= csp_qstring(vb,current->str,current->i); if (st) return st;
  }
  return adns_s_ok;
}

/*
 * _hinfo   (cs)
 */

static adns_status cs_hinfo(vbuf *vb, const void *datap) {
  const adns_rr_intstrpair *rrp= datap;
  adns_status st;

  st= csp_qstring(vb,rrp->array[0].str,rrp->array[0].i);  if (st) return st;
  CSP_ADDSTR(" ");
  st= csp_qstring(vb,rrp->array[1].str,rrp->array[1].i);  if (st) return st;
  return adns_s_ok;
}

/*
 * _inaddr   (pa,dip,di,cs +search_sortlist)
 */

static adns_status pa_inaddr(const parseinfo *pai, int cbyte,
                             int max, void *datap) {
  struct in_addr *storeto= datap;
  
  if (max-cbyte != 4) return adns_s_invaliddata;
  memcpy(storeto, pai->dgram + cbyte, 4);
  return adns_s_ok;
}

static int search_sortlist(adns_state ads, struct in_addr ad) {
  const struct sortlist *slp;
  int i;
  
  for (i=0, slp=ads->sortlist;
       i<ads->nsortlist &&
         !((ad.s_addr & slp->mask.s_addr) == slp->base.s_addr);
       i++, slp++);
  return i;
}

static int dip_inaddr(adns_state ads, struct in_addr a, struct in_addr b) {
  int ai, bi;
  
  if (!ads->nsortlist) return 0;

  ai= search_sortlist(ads,a);
  bi= search_sortlist(ads,b);
  return bi<ai;
}

static int di_inaddr(adns_state ads,
                     const void *datap_a, const void *datap_b) {
  const struct in_addr *ap= datap_a, *bp= datap_b;

  return dip_inaddr(ads,*ap,*bp);
}

static adns_status cs_inaddr(vbuf *vb, const void *datap) {
  const struct in_addr *rrp= datap, rr= *rrp;
  const char *ia;

  ia= inet_ntoa(rr); assert(ia);
  CSP_ADDSTR(ia);
  return adns_s_ok;
}

/*
 * _addr   (pa,di,div,csp,cs,gsz)
 */

static adns_status pa_addr(const parseinfo *pai, int cbyte,
                           int max, void *datap) {
  adns_rr_addr *storeto= datap;
  const byte *dgram= pai->dgram;

  if (max-cbyte != 4) return adns_s_invaliddata;
  storeto->len= sizeof(storeto->addr.inet);
  memset(&storeto->addr,0,sizeof(storeto->addr.inet));
  storeto->addr.inet.sin_family= AF_INET;
  memcpy(&storeto->addr.inet.sin_addr,dgram+cbyte,4);
  return adns_s_ok;
}

static int di_addr(adns_state ads, const void *datap_a, const void *datap_b) {
  const adns_rr_addr *ap= datap_a, *bp= datap_b;

  assert(ap->addr.sa.sa_family == AF_INET);
  return dip_inaddr(ads, ap->addr.inet.sin_addr, bp->addr.inet.sin_addr);
}

static int div_addr(void *context, const void *datap_a, const void *datap_b) {
  const adns_state ads= context;

  return di_addr(ads, datap_a, datap_b);
}                    

static adns_status csp_addr(vbuf *vb, const adns_rr_addr *rrp) {
  const char *ia;
  char buf[30];

  switch (rrp->addr.inet.sin_family) {
  case AF_INET:
    CSP_ADDSTR("INET ");
    ia= inet_ntoa(rrp->addr.inet.sin_addr); assert(ia);
    CSP_ADDSTR(ia);
    break;
  default:
    sprintf(buf,"AF=%u",rrp->addr.sa.sa_family);
    CSP_ADDSTR(buf);
    break;
  }
  return adns_s_ok;
}

static adns_status cs_addr(vbuf *vb, const void *datap) {
  const adns_rr_addr *rrp= datap;

  return csp_addr(vb,rrp);
}

static int gsz_addr(const typeinfo *typei, adns_rrtype type) {
  return type & adns__qtf_bigaddr ?
    sizeof(adns_rr_addr) : sizeof(adns_rr_addr_v4only);
}

/*
 * _domain      (pap,csp,cs)
 * _dom_raw     (pa)
 */

static adns_status pap_domain(const parseinfo *pai, int *cbyte_io, int max,
                              char **domain_r, parsedomain_flags flags) {
  adns_status st;
  char *dm;
  
  st= adns__parse_domain(pai->qu->ads, pai->serv, pai->qu, &pai->qu->vb, flags,
                         pai->dgram,pai->dglen, cbyte_io, max);
  if (st) return st;
  if (!pai->qu->vb.used) return adns_s_invaliddata;

  dm= adns__alloc_interim(pai->qu, pai->qu->vb.used+1);
  if (!dm) R_NOMEM;

  dm[pai->qu->vb.used]= 0;
  memcpy(dm,pai->qu->vb.buf,pai->qu->vb.used);
  
  *domain_r= dm;
  return adns_s_ok;
}

static adns_status csp_domain(vbuf *vb, const char *domain) {
  CSP_ADDSTR(domain);
  if (!*domain) CSP_ADDSTR(".");
  return adns_s_ok;
}

static adns_status cs_domain(vbuf *vb, const void *datap) {
  const char *const *domainp= datap;
  return csp_domain(vb,*domainp);
}

static adns_status pa_dom_raw(const parseinfo *pai, int cbyte,
                              int max, void *datap) {
  char **rrp= datap;
  adns_status st;

  st= pap_domain(pai, &cbyte, max, rrp, pdf_quoteok);
  if (st) return st;
  
  if (cbyte != max) return adns_s_invaliddata;
  return adns_s_ok;
}

/*
 * _host_raw   (pa)
 */

static adns_status pa_host_raw(const parseinfo *pai, int cbyte,
                               int max, void *datap) {
  char **rrp= datap;
  adns_status st;

  st= pap_domain(pai, &cbyte, max, rrp,
                 pai->qu->flags & adns_qf_quoteok_anshost ? pdf_quoteok : 0);
  if (st) return st;
  
  if (cbyte != max) return adns_s_invaliddata;
  return adns_s_ok;
}

/*
 * _hostaddr   (pap,pa,dip,di,mfp,mf,csp,cs +pap_findaddrs, icb_hostaddr)
 */

static adns_status pap_findaddrs(const parseinfo *pai, adns_rr_hostaddr *ha,
                                 size_t addrsz,
                                 int *cbyte_io, int count, int dmstart) {
  int rri, naddrs;
  int type, class, rdlen, rdstart, ownermatched;
  unsigned long ttl;
  adns_status st;
  
  for (rri=0, naddrs=-1; rri<count; rri++) {
    st= adns__findrr_anychk(pai->qu, pai->serv, pai->dgram,
                            pai->dglen, cbyte_io,
                            &type, &class, &ttl, &rdlen, &rdstart,
                            pai->dgram, pai->dglen, dmstart, &ownermatched);
    if (st) return st;
    if (!ownermatched || class != DNS_CLASS_IN || type != adns_r_a) {
      if (naddrs>0) break; else continue;
    }
    if (naddrs == -1) {
      naddrs= 0;
    }
    if (!adns__vbuf_ensure(&pai->qu->vb, (naddrs+1)*addrsz))
      R_NOMEM;
    adns__update_expires(pai->qu,ttl,pai->now);
    st= pa_addr(pai, rdstart,rdstart+rdlen, pai->qu->vb.buf + naddrs*addrsz);
    if (st) return st;
    naddrs++;
  }
  if (naddrs >= 0) {
    ha->addrs= adns__alloc_interim(pai->qu, naddrs*addrsz);
    if (!ha->addrs) R_NOMEM;
    memcpy(ha->addrs, pai->qu->vb.buf, naddrs*addrsz);
    ha->naddrs= naddrs;
    ha->astatus= adns_s_ok;

    adns__isort(ha->addrs, naddrs, addrsz, pai->qu->vb.buf,
                div_addr, pai->ads);
  }
  return adns_s_ok;
}

static void icb_hostaddr(adns_query parent, adns_query child) {
  adns_answer *cans= child->answer;
  adns_rr_hostaddr *rrp= child->ctx.pinfo.hostaddr;
  adns_state ads= parent->ads;
  adns_status st;
  size_t addrsz= gsz_addr(0, parent->answer->type);

  st= cans->status;
  rrp->astatus= st;
  rrp->naddrs= (st>0 && st<=adns_s_max_tempfail) ? -1 : cans->nrrs;
  rrp->addrs= cans->rrs.addr;
  adns__transfer_interim(child, parent, rrp->addrs, rrp->naddrs*addrsz);

  if (parent->children.head) {
    LIST_LINK_TAIL(ads->childw,parent);
  } else {
    adns__query_done(parent);
  }
}

static adns_status pap_hostaddr(const parseinfo *pai, int *cbyte_io,
                                int max, adns_rr_hostaddr *rrp) {
  adns_status st;
  int dmstart, cbyte;
  qcontext ctx;
  int id;
  adns_query nqu;
  adns_queryflags nflags;
  size_t addrsz= gsz_addr(0, pai->qu->answer->type);

  dmstart= cbyte= *cbyte_io;
  st= pap_domain(pai, &cbyte, max, &rrp->host,
                 pai->qu->flags & adns_qf_quoteok_anshost ? pdf_quoteok : 0);
  if (st) return st;
  *cbyte_io= cbyte;

  rrp->astatus= adns_s_ok;
  rrp->naddrs= -1;
  rrp->addrs= 0;

  cbyte= pai->nsstart;

  st= pap_findaddrs(pai, rrp,addrsz, &cbyte, pai->nscount, dmstart);
  if (st) return st;
  if (rrp->naddrs != -1) return adns_s_ok;

  st= pap_findaddrs(pai, rrp,addrsz, &cbyte, pai->arcount, dmstart);
  if (st) return st;
  if (rrp->naddrs != -1) return adns_s_ok;

  st= adns__mkquery_frdgram(pai->ads, &pai->qu->vb, &id,
                            pai->dgram, pai->dglen, dmstart,
                            adns_r_addr, adns_qf_quoteok_query);
  if (st) return st;

  ctx.ext= 0;
  ctx.callback= icb_hostaddr;
  ctx.pinfo.hostaddr= rrp;
  memset(&ctx.tinfo, 0, sizeof(ctx.tinfo));
  
  nflags= adns_qf_quoteok_query;
  if (!(pai->qu->flags & adns_qf_cname_loose)) nflags |= adns_qf_cname_forbid;
  
  st= adns__internal_submit(pai->ads, &nqu, adns__findtype(adns_r_addr),
                            ((adns_r_addr & adns_rrt_reprmask) |
                             (pai->qu->answer->type & ~adns_rrt_reprmask)),
                            &pai->qu->vb, id, nflags, pai->now, &ctx);
  if (st) return st;

  nqu->parent= pai->qu;
  LIST_LINK_TAIL_PART(pai->qu->children,nqu,siblings.);

  return adns_s_ok;
}

static adns_status pa_hostaddr(const parseinfo *pai, int cbyte,
                               int max, void *datap) {
  adns_rr_hostaddr *rrp= datap;
  adns_status st;

  st= pap_hostaddr(pai, &cbyte, max, rrp);
  if (st) return st;
  if (cbyte != max) return adns_s_invaliddata;

  return adns_s_ok;
}

static int dip_hostaddr(adns_state ads,
                        const adns_rr_hostaddr *ap, const adns_rr_hostaddr *bp) {
  if (ap->astatus != bp->astatus) return ap->astatus;
  if (ap->astatus) return 0;

  assert(ap->addrs[0].addr.sa.sa_family == AF_INET);
  assert(bp->addrs[0].addr.sa.sa_family == AF_INET);
  return dip_inaddr(ads,
                    ap->addrs[0].addr.inet.sin_addr,
                    bp->addrs[0].addr.inet.sin_addr);
}

static int di_hostaddr(adns_state ads,
                       const void *datap_a, const void *datap_b) {
  const adns_rr_hostaddr *ap= datap_a, *bp= datap_b;

  return dip_hostaddr(ads, ap,bp);
}

static void mfp_hostaddr(adns_query qu, adns_rr_hostaddr *rrp) {
  void *tablev;
  size_t addrsz= gsz_addr(0, qu->answer->type);

  adns__makefinal_str(qu,&rrp->host);
  tablev= rrp->addrs;
  adns__makefinal_block(qu, &tablev, rrp->naddrs*addrsz);
  rrp->addrs= tablev;
}

static void mf_hostaddr(adns_query qu, void *datap) {
  adns_rr_hostaddr *rrp= datap;

  mfp_hostaddr(qu,rrp);
}

static adns_status csp_hostaddr(vbuf *vb, const adns_rr_hostaddr *rrp) {
  const char *errstr;
  adns_status st;
  char buf[20];
  int i;

  st= csp_domain(vb,rrp->host);  if (st) return st;

  CSP_ADDSTR(" ");
  CSP_ADDSTR(adns_errtypeabbrev(rrp->astatus));

  sprintf(buf," %d ",rrp->astatus);
  CSP_ADDSTR(buf);

  CSP_ADDSTR(adns_errabbrev(rrp->astatus));
  CSP_ADDSTR(" ");

  errstr= adns_strerror(rrp->astatus);
  st= csp_qstring(vb,errstr,strlen(errstr));  if (st) return st;
  
  if (rrp->naddrs >= 0) {
    CSP_ADDSTR(" (");
    for (i=0; i<rrp->naddrs; i++) {
      CSP_ADDSTR(" ");
      st= csp_addr(vb,&rrp->addrs[i]);
    }
    CSP_ADDSTR(" )");
  } else {
    CSP_ADDSTR(" ?");
  }
  return adns_s_ok;
}

static adns_status cs_hostaddr(vbuf *vb, const void *datap) {
  const adns_rr_hostaddr *rrp= datap;

  return csp_hostaddr(vb,rrp);
}

/*
 * _mx_raw   (pa,di)
 */

static adns_status pa_mx_raw(const parseinfo *pai, int cbyte,
                             int max, void *datap) {
  const byte *dgram= pai->dgram;
  adns_rr_intstr *rrp= datap;
  adns_status st;
  int pref;

  if (cbyte+2 > max) return adns_s_invaliddata;
  GET_W(cbyte,pref);
  rrp->i= pref;
  st= pap_domain(pai, &cbyte, max, &rrp->str,
                 pai->qu->flags & adns_qf_quoteok_anshost ? pdf_quoteok : 0);
  if (st) return st;
  
  if (cbyte != max) return adns_s_invaliddata;
  return adns_s_ok;
}

static int di_mx_raw(adns_state ads, const void *datap_a, const void *datap_b) {
  const adns_rr_intstr *ap= datap_a, *bp= datap_b;

  if (ap->i < bp->i) return 0;
  if (ap->i > bp->i) return 1;
  return 0;
}

/*
 * _mx   (pa,di)
 */

static adns_status pa_mx(const parseinfo *pai, int cbyte,
                         int max, void *datap) {
  const byte *dgram= pai->dgram;
  adns_rr_inthostaddr *rrp= datap;
  adns_status st;
  int pref;

  if (cbyte+2 > max) return adns_s_invaliddata;
  GET_W(cbyte,pref);
  rrp->i= pref;
  st= pap_hostaddr(pai, &cbyte, max, &rrp->ha);
  if (st) return st;
  
  if (cbyte != max) return adns_s_invaliddata;
  return adns_s_ok;
}

static int di_mx(adns_state ads, const void *datap_a, const void *datap_b) {
  const adns_rr_inthostaddr *ap= datap_a, *bp= datap_b;

  if (ap->i < bp->i) return 0;
  if (ap->i > bp->i) return 1;
  return dip_hostaddr(ads, &ap->ha, &bp->ha);
}

/*
 * _inthostaddr  (mf,cs)
 */

static void mf_inthostaddr(adns_query qu, void *datap) {
  adns_rr_inthostaddr *rrp= datap;

  mfp_hostaddr(qu,&rrp->ha);
}

static adns_status cs_inthostaddr(vbuf *vb, const void *datap) {
  const adns_rr_inthostaddr *rrp= datap;
  char buf[10];

  sprintf(buf,"%u ",rrp->i);
  CSP_ADDSTR(buf);

  return csp_hostaddr(vb,&rrp->ha);
}

/*
 * _inthost  (cs)
 */

static adns_status cs_inthost(vbuf *vb, const void *datap) {
  const adns_rr_intstr *rrp= datap;
  char buf[10];

  sprintf(buf,"%u ",rrp->i);
  CSP_ADDSTR(buf);
  return csp_domain(vb,rrp->str);
}

/*
 * _ptr   (ckl,pa +icb_ptr)
 */

static adns_status ckl_ptr(adns_state ads, adns_queryflags flags,
                           union checklabel_state *cls, qcontext *ctx,
                           int labnum, const char *label, int lablen) {
  static const char *const (expectdomain[])= { DNS_INADDR_ARPA };
  char *ep;
  const char *ed;
  char labbuf[4];
  int l;

  if (labnum < 4) {
    if (lablen<=0 || lablen>3) return adns_s_querydomainwrong;
    memcpy(labbuf, label, lablen);
    labbuf[lablen]= 0;
    cls->ptr.ipv[3-labnum]= strtoul(labbuf,&ep,10);
    if (*ep) return adns_s_querydomainwrong;
    if (lablen>1 && *label=='0') return adns_s_querydomainwrong;
  } else if (labnum < 4 + sizeof(expectdomain)/sizeof(*expectdomain)) {
    ed= expectdomain[labnum-4];
    l= strlen(ed);
    if (lablen != l || memcmp(label, ed, l)) return adns_s_querydomainwrong;
  } else {
    if (lablen) return adns_s_querydomainwrong;
    ctx->tinfo.ptr.addr.s_addr=
      htonl((cls->ptr.ipv[0]<<24) | (cls->ptr.ipv[1]<<16) |
            (cls->ptr.ipv[2]<< 8) | (cls->ptr.ipv[3]));
  }
  return adns_s_ok;
}

static void icb_ptr(adns_query parent, adns_query child) {
  adns_answer *cans= child->answer;
  const struct in_addr *queried;
  const unsigned char *found;
  adns_state ads= parent->ads;
  int i;

  if (cans->status == adns_s_nxdomain || cans->status == adns_s_nodata) {
    adns__query_fail(parent,adns_s_inconsistent);
    return;
  } else if (cans->status) {
    adns__query_fail(parent,cans->status);
    return;
  }

  queried= &parent->ctx.tinfo.ptr.addr;
  for (i=0, found=cans->rrs.bytes; i<cans->nrrs; i++, found+=cans->rrsz) {
    if (!memcmp(queried,found,cans->rrsz)) {
      if (!parent->children.head) {
        adns__query_done(parent);
        return;
      } else {
        LIST_LINK_TAIL(ads->childw,parent);
        return;
      }
    }
  }

  adns__query_fail(parent,adns_s_inconsistent);
}

static adns_status pa_ptr(const parseinfo *pai, int dmstart,
                          int max, void *datap) {
  char **rrp= datap;
  adns_status st;
  int cbyte, id;
  adns_query nqu;
  qcontext ctx;

  cbyte= dmstart;
  st= pap_domain(pai, &cbyte, max, rrp,
                 pai->qu->flags & adns_qf_quoteok_anshost ? pdf_quoteok : 0);
  if (st) return st;
  if (cbyte != max) return adns_s_invaliddata;

  st= adns__mkquery_frdgram(pai->ads, &pai->qu->vb, &id,
                            pai->dgram, pai->dglen, dmstart,
                            adns_r_a, adns_qf_quoteok_query);
  if (st) return st;

  ctx.ext= 0;
  ctx.callback= icb_ptr;
  memset(&ctx.pinfo,0,sizeof(ctx.pinfo));
  memset(&ctx.tinfo,0,sizeof(ctx.tinfo));
  st= adns__internal_submit(pai->ads, &nqu, adns__findtype(adns_r_a),
                            adns_r_a, &pai->qu->vb, id, adns_qf_quoteok_query,
                            pai->now, &ctx);
  if (st) return st;

  nqu->parent= pai->qu;
  LIST_LINK_TAIL_PART(pai->qu->children,nqu,siblings.);
  return adns_s_ok;
}

/*
 * _strpair   (mf)
 */

static void mf_strpair(adns_query qu, void *datap) {
  adns_rr_strpair *rrp= datap;

  adns__makefinal_str(qu,&rrp->array[0]);
  adns__makefinal_str(qu,&rrp->array[1]);
}

/*
 * _intstrpair   (mf)
 */

static void mf_intstrpair(adns_query qu, void *datap) {
  adns_rr_intstrpair *rrp= datap;

  adns__makefinal_str(qu,&rrp->array[0].str);
  adns__makefinal_str(qu,&rrp->array[1].str);
}

/*
 * _hinfo   (pa)
 */

static adns_status pa_hinfo(const parseinfo *pai, int cbyte,
                            int max, void *datap) {
  adns_rr_intstrpair *rrp= datap;
  adns_status st;
  int i;

  for (i=0; i<2; i++) {
    st= pap_qstring(pai, &cbyte, max, &rrp->array[i].i, &rrp->array[i].str);
    if (st) return st;
  }

  if (cbyte != max) return adns_s_invaliddata;
  
  return adns_s_ok;
}

/*
 * _mailbox   (pap,cs +pap_mailbox822)
 */

static adns_status pap_mailbox822(const parseinfo *pai,
                                  int *cbyte_io, int max, char **mb_r) {
  int lablen, labstart, i, needquote, c, r, neednorm;
  const unsigned char *p;
  char *str;
  findlabel_state fls;
  adns_status st;
  vbuf *vb;

  vb= &pai->qu->vb;
  vb->used= 0;
  adns__findlabel_start(&fls, pai->ads,
                        -1, pai->qu,
                        pai->dgram, pai->dglen, max,
                        *cbyte_io, cbyte_io);
  st= adns__findlabel_next(&fls,&lablen,&labstart);
  if (!lablen) {
    adns__vbuf_appendstr(vb,".");
    goto x_ok;
  }

  neednorm= 1;
  for (i=0, needquote=0, p= pai->dgram+labstart; i<lablen; i++) {
    c= *p++;
    if ((c&~128) < 32 || (c&~128) == 127) return adns_s_invaliddata;
    if (c == '.' && !neednorm) neednorm= 1;
    else if (c==' ' || c>=127 || ctype_822special(c)) needquote++;
    else neednorm= 0;
  }

  if (needquote || neednorm) {
    r= adns__vbuf_ensure(vb, lablen+needquote+4); if (!r) R_NOMEM;
    adns__vbuf_appendq(vb,"\"",1);
    for (i=0, needquote=0, p= pai->dgram+labstart; i<lablen; i++, p++) {
      c= *p;
      if (c == '"' || c=='\\') adns__vbuf_appendq(vb,"\\",1);
      adns__vbuf_appendq(vb,p,1);
    }
    adns__vbuf_appendq(vb,"\"",1);
  } else {
    r= adns__vbuf_append(vb, pai->dgram+labstart, lablen); if (!r) R_NOMEM;
  }

  r= adns__vbuf_appendstr(vb,"@"); if (!r) R_NOMEM;

  st= adns__parse_domain_more(&fls,pai->ads, pai->qu,vb,0, pai->dgram);
  if (st) return st;

 x_ok:
  str= adns__alloc_interim(pai->qu, vb->used+1); if (!str) R_NOMEM;
  memcpy(str,vb->buf,vb->used);
  str[vb->used]= 0;
  *mb_r= str;
  return adns_s_ok;
}

static adns_status pap_mailbox(const parseinfo *pai, int *cbyte_io, int max,
                               char **mb_r) {
  if (pai->qu->typei->typekey & adns__qtf_mail822) {
    return pap_mailbox822(pai, cbyte_io, max, mb_r);
  } else {
    return pap_domain(pai, cbyte_io, max, mb_r, pdf_quoteok);
  }
}

static adns_status csp_mailbox(vbuf *vb, const char *mailbox) {
  return csp_domain(vb,mailbox);
}

/*
 * _rp   (pa,cs)
 */

static adns_status pa_rp(const parseinfo *pai, int cbyte,
                         int max, void *datap) {
  adns_rr_strpair *rrp= datap;
  adns_status st;

  st= pap_mailbox(pai, &cbyte, max, &rrp->array[0]);
  if (st) return st;

  st= pap_domain(pai, &cbyte, max, &rrp->array[1], pdf_quoteok);
  if (st) return st;

  if (cbyte != max) return adns_s_invaliddata;
  return adns_s_ok;
}

static adns_status cs_rp(vbuf *vb, const void *datap) {
  const adns_rr_strpair *rrp= datap;
  adns_status st;

  st= csp_mailbox(vb,rrp->array[0]);  if (st) return st;
  CSP_ADDSTR(" ");
  st= csp_domain(vb,rrp->array[1]);  if (st) return st;

  return adns_s_ok;
}  

/*
 * _soa   (pa,mf,cs)
 */

static adns_status pa_soa(const parseinfo *pai, int cbyte,
                          int max, void *datap) {
  adns_rr_soa *rrp= datap;
  const byte *dgram= pai->dgram;
  adns_status st;
  int msw, lsw, i;

  st= pap_domain(pai, &cbyte, max, &rrp->mname,
                 pai->qu->flags & adns_qf_quoteok_anshost ? pdf_quoteok : 0);
  if (st) return st;

  st= pap_mailbox(pai, &cbyte, max, &rrp->rname);
  if (st) return st;

  if (cbyte+20 != max) return adns_s_invaliddata;
  
  for (i=0; i<5; i++) {
    GET_W(cbyte,msw);
    GET_W(cbyte,lsw);
    (&rrp->serial)[i]= (msw<<16) | lsw;
  }

  return adns_s_ok;
}

static void mf_soa(adns_query qu, void *datap) {
  adns_rr_soa *rrp= datap;

  adns__makefinal_str(qu,&rrp->mname);
  adns__makefinal_str(qu,&rrp->rname);
}

static adns_status cs_soa(vbuf *vb, const void *datap) {
  const adns_rr_soa *rrp= datap;
  char buf[20];
  int i;
  adns_status st;
  
  st= csp_domain(vb,rrp->mname);  if (st) return st;
  CSP_ADDSTR(" ");
  st= csp_mailbox(vb,rrp->rname);  if (st) return st;

  for (i=0; i<5; i++) {
    sprintf(buf," %lu",(&rrp->serial)[i]);
    CSP_ADDSTR(buf);
  }

  return adns_s_ok;
}

/*
 * _srv*  (ckl,(pap),pa*2,mf*2,di,(csp),cs*2,postsort)
 */

static adns_status ckl_srv(adns_state ads, adns_queryflags flags,
                           union checklabel_state *cls, qcontext *ctx,
                           int labnum, const char *label, int lablen) {
  if (labnum < 2 && !(flags & adns_qf_quoteok_query)) {
    if (!lablen || label[0] != '_') return adns_s_querydomaininvalid;
    return adns_s_ok;
  }
  return adns__ckl_hostname(ads, flags, cls, ctx, labnum, label, lablen);
}

static adns_status pap_srv_begin(const parseinfo *pai, int *cbyte_io, int max,
                                 adns_rr_srvha *rrp
                                   /* might be adns_rr_srvraw* */) {
  const byte *dgram= pai->dgram;
  int ti, cbyte;

  cbyte= *cbyte_io;
  if ((*cbyte_io += 6) > max) return adns_s_invaliddata;
  
  rrp->priority= GET_W(cbyte, ti);
  rrp->weight=   GET_W(cbyte, ti);
  rrp->port=     GET_W(cbyte, ti);
  return adns_s_ok;
}

static adns_status pa_srvraw(const parseinfo *pai, int cbyte,
                             int max, void *datap) {
  adns_rr_srvraw *rrp= datap;
  adns_status st;

  st= pap_srv_begin(pai,&cbyte,max,datap);
  if (st) return st;
  
  st= pap_domain(pai, &cbyte, max, &rrp->host,
                 pai->qu->flags & adns_qf_quoteok_anshost ? pdf_quoteok : 0);
  if (st) return st;
  
  if (cbyte != max) return adns_s_invaliddata;
  return adns_s_ok;
}

static adns_status pa_srvha(const parseinfo *pai, int cbyte,
                            int max, void *datap) {
  adns_rr_srvha *rrp= datap;
  adns_status st;

  st= pap_srv_begin(pai,&cbyte,max,datap);       if (st) return st;
  st= pap_hostaddr(pai, &cbyte, max, &rrp->ha);  if (st) return st;
  if (cbyte != max) return adns_s_invaliddata;
  return adns_s_ok;
}

static void mf_srvraw(adns_query qu, void *datap) {
  adns_rr_srvraw *rrp= datap;
  adns__makefinal_str(qu, &rrp->host);
}

static void mf_srvha(adns_query qu, void *datap) {
  adns_rr_srvha *rrp= datap;
  mfp_hostaddr(qu,&rrp->ha);
}

static int di_srv(adns_state ads, const void *datap_a, const void *datap_b) {
  const adns_rr_srvraw *ap= datap_a, *bp= datap_b;
    /* might be const adns_rr_svhostaddr* */

  if (ap->priority < bp->priority) return 0;
  if (ap->priority > bp->priority) return 1;
  return 0;
}

static adns_status csp_srv_begin(vbuf *vb, const adns_rr_srvha *rrp
                                   /* might be adns_rr_srvraw* */) {
  char buf[30];
  sprintf(buf,"%u %u %u ", rrp->priority, rrp->weight, rrp->port);
  CSP_ADDSTR(buf);
  return adns_s_ok;
}

static adns_status cs_srvraw(vbuf *vb, const void *datap) {
  const adns_rr_srvraw *rrp= datap;
  adns_status st;
  
  st= csp_srv_begin(vb,(const void*)rrp);  if (st) return st;
  return csp_domain(vb,rrp->host);
}

static adns_status cs_srvha(vbuf *vb, const void *datap) {
  const adns_rr_srvha *rrp= datap;
  adns_status st;

  st= csp_srv_begin(vb,(const void*)datap);  if (st) return st;
  return csp_hostaddr(vb,&rrp->ha);
}

static void postsort_srv(adns_state ads, void *array, int nrrs,int rrsz,
                         const struct typeinfo *typei) {
  /* we treat everything in the array as if it were an adns_rr_srvha
   * even though the array might be of adns_rr_srvraw.  That's OK
   * because they have the same prefix, which is all we access.
   * We use rrsz, too, rather than naive array indexing, of course.
   */
  char *workbegin, *workend, *search, *arrayend;
  const adns_rr_srvha *rr;
  union { adns_rr_srvha ha; adns_rr_srvraw raw; } rrtmp;
  int cpriority, totalweight, runtotal;
  long randval;

  assert(rrsz <= sizeof(rrtmp));
  for (workbegin= array, arrayend= workbegin + rrsz * nrrs;
       workbegin < arrayend;
       workbegin= workend) {
    cpriority= (rr=(void*)workbegin)->priority;
    
    for (workend= workbegin, totalweight= 0;
         workend < arrayend && (rr=(void*)workend)->priority == cpriority;
         workend += rrsz) {
      totalweight += rr->weight;
    }

    /* Now workbegin..(workend-1) incl. are exactly all of the RRs of
     * cpriority.  From now on, workbegin points to the `remaining'
     * records: we select one record at a time (RFC2782 `Usage rules'
     * and `Format of the SRV RR' subsection `Weight') to place at
     * workbegin (swapping with the one that was there, and then
     * advance workbegin. */
    for (;
         workbegin + rrsz < workend; /* don't bother if just one */
         workbegin += rrsz) {
      
      randval= nrand48(ads->rand48xsubi);
      randval %= (totalweight + 1);
        /* makes it into 0..totalweight inclusive; with 2^10 RRs,
         * totalweight must be <= 2^26 so probability nonuniformity is
         * no worse than 1 in 2^(31-26) ie 1 in 2^5, ie
         *  abs(log(P_intended(RR_i) / P_actual(RR_i)) <= log(2^-5).
         */

      for (search=workbegin, runtotal=0;
           (runtotal += (rr=(void*)search)->weight) < randval;
           search += rrsz);
      assert(search < arrayend);
      totalweight -= rr->weight;
      if (search != workbegin) {
        memcpy(&rrtmp, workbegin, rrsz);
        memcpy(workbegin, search, rrsz);
        memcpy(search, &rrtmp, rrsz);
      }
    }
  }
  /* tests:
   *  dig -t srv _srv._tcp.test.iwj.relativity.greenend.org.uk.
   *   ./adnshost_s -t srv- _sip._udp.voip.net.cam.ac.uk.
   *   ./adnshost_s -t srv- _jabber._tcp.jabber.org
   */
}

/*
 * _byteblock   (mf)
 */

static void mf_byteblock(adns_query qu, void *datap) {
  adns_rr_byteblock *rrp= datap;
  void *bytes= rrp->data;
  adns__makefinal_block(qu,&bytes,rrp->len);
  rrp->data= bytes;
}

/*
 * _opaque   (pa,cs)
 */

static adns_status pa_opaque(const parseinfo *pai, int cbyte,
                             int max, void *datap) {
  adns_rr_byteblock *rrp= datap;

  rrp->len= max - cbyte;
  rrp->data= adns__alloc_interim(pai->qu, rrp->len);
  if (!rrp->data) R_NOMEM;
  memcpy(rrp->data, pai->dgram + cbyte, rrp->len);
  return adns_s_ok;
}

static adns_status cs_opaque(vbuf *vb, const void *datap) {
  const adns_rr_byteblock *rrp= datap;
  char buf[10];
  int l;
  unsigned char *p;

  sprintf(buf,"\\# %d",rrp->len);
  CSP_ADDSTR(buf);
  
  for (l= rrp->len, p= rrp->data;
       l>=4;
       l -= 4, p += 4) {
    sprintf(buf," %02x%02x%02x%02x",p[0],p[1],p[2],p[3]);
    CSP_ADDSTR(buf);
  }
  for (;
       l>0;
       l--, p++) {
    sprintf(buf," %02x",*p);
    CSP_ADDSTR(buf);
  }
  return adns_s_ok;
}
  
/*
 * _flat   (mf)
 */

static void mf_flat(adns_query qu, void *data) { }

/*
 * Now the table.
 */

#define TYPESZ_M(member)           (sizeof(*((adns_answer*)0)->rrs.member))

#define DEEP_TYPE(code,rrt,fmt,memb,parser,comparer,/*printer*/...)     \
 { adns_r_##code&adns_rrt_reprmask, rrt,fmt,TYPESZ_M(memb), mf_##memb,  \
     GLUE(cs_, CAR(__VA_ARGS__)),pa_##parser,di_##comparer,             \
     adns__ckl_hostname, 0, adns__getrrsz_default, CDR(__VA_ARGS__) }
#define FLAT_TYPE(code,rrt,fmt,memb,parser,comparer,/*printer*/...)     \
 { adns_r_##code&adns_rrt_reprmask, rrt,fmt,TYPESZ_M(memb), mf_flat,    \
     GLUE(cs_, CAR(__VA_ARGS__)),pa_##parser,di_##comparer,             \
     adns__ckl_hostname, 0, adns__getrrsz_default, CDR(__VA_ARGS__) }

#define di_0 0

static const typeinfo typeinfos[] = {
/* Must be in ascending order of rrtype ! */
/* mem-mgmt code  rrt     fmt   member   parser      comparer  printer */

FLAT_TYPE(a,      "A",     0,   inaddr,    inaddr,  inaddr,inaddr          ),
DEEP_TYPE(ns_raw, "NS",   "raw",str,       host_raw,0,     domain          ),
DEEP_TYPE(cname,  "CNAME", 0,   str,       dom_raw, 0,     domain          ),
DEEP_TYPE(soa_raw,"SOA",  "raw",soa,       soa,     0,     soa             ),
DEEP_TYPE(ptr_raw,"PTR",  "raw",str,       host_raw,0,     domain          ),
DEEP_TYPE(hinfo,  "HINFO", 0,   intstrpair,hinfo,   0,     hinfo           ),
DEEP_TYPE(mx_raw, "MX",   "raw",intstr,    mx_raw,  mx_raw,inthost         ),
DEEP_TYPE(txt,    "TXT",   0,   manyistr,  txt,     0,     txt             ),
DEEP_TYPE(rp_raw, "RP",   "raw",strpair,   rp,      0,     rp              ),
DEEP_TYPE(srv_raw,"SRV",  "raw",srvraw ,   srvraw,  srv,   srvraw,
                              .checklabel= ckl_srv, .postsort= postsort_srv),

FLAT_TYPE(addr,   "A",  "addr", addr,      addr,    addr,  addr,
                                                         .getrrsz= gsz_addr),
DEEP_TYPE(ns,     "NS", "+addr",hostaddr,  hostaddr,hostaddr,hostaddr      ),
DEEP_TYPE(ptr,    "PTR","checked",str,     ptr,     0,     domain,
                                                       .checklabel= ckl_ptr),
DEEP_TYPE(mx,     "MX", "+addr",inthostaddr,mx,     mx,    inthostaddr,    ),
DEEP_TYPE(srv,    "SRV","+addr",srvha,     srvha,   srv,   srvha,
                              .checklabel= ckl_srv, .postsort= postsort_srv),

DEEP_TYPE(soa,    "SOA","822",  soa,       soa,     0,     soa             ),
DEEP_TYPE(rp,     "RP", "822",  strpair,   rp,      0,     rp              ),
};

static const typeinfo typeinfo_unknown=
DEEP_TYPE(unknown,0, "unknown",byteblock,opaque,  0,     opaque            );

const typeinfo *adns__findtype(adns_rrtype type) {
  const typeinfo *begin, *end, *mid;

  if (type & adns_r_unknown) return &typeinfo_unknown;
  type &= adns_rrt_reprmask;

  begin= typeinfos;  end= typeinfos+(sizeof(typeinfos)/sizeof(typeinfo));

  while (begin < end) {
    mid= begin + ((end-begin)>>1);
    if (mid->typekey == type) return mid;
    if (type > mid->typekey) begin= mid+1;
    else end= mid;
  }
  return 0;
}