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

   1 /*
   2  * transmit.c
   3  * - construct queries
   4  * - send queries
   5  */
   6 /*
   7  *  This file is part of adns, which is
   8  *    Copyright (C) 1997-2000,2003,2006  Ian Jackson
   9  *    Copyright (C) 1999-2000,2003,2006  Tony Finch
  10  *    Copyright (C) 1991 Massachusetts Institute of Technology
  11  *  (See the file INSTALL for full details.)
  12  *
  13  *  This program is free software; you can redistribute it and/or modify
  14  *  it under the terms of the GNU General Public License as published by
  15  *  the Free Software Foundation; either version 2, or (at your option)
  16  *  any later version.
  17  *
  18  *  This program is distributed in the hope that it will be useful,
  19  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  *  GNU General Public License for more details.
  22  *
  23  *  You should have received a copy of the GNU General Public License
  24  *  along with this program; if not, write to the Free Software Foundation,
  25  *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  26  */
  27
  28 #include <errno.h>
  29
  30 #include <sys/types.h>
  31 #include <sys/uio.h>
  32
  33 #include "internal.h"
  34 #include "tvarith.h"
  35
  36 #define MKQUERY_START(vb) (rqp= (vb)->buf+(vb)->used)
  37 #define MKQUERY_ADDB(b) *rqp++= (b)
  38 #define MKQUERY_ADDW(w) (MKQUERY_ADDB(((w)>>8)&0x0ff), MKQUERY_ADDB((w)&0x0ff))
  39 #define MKQUERY_STOP(vb) ((vb)->used= rqp-(vb)->buf)
  40
  41 static adns_status mkquery_header(adns_state ads, vbuf *vb,
  42                                   int *id_r, int qdlen) {
  43   int id;
  44   byte *rqp;
  45
  46   if (!adns__vbuf_ensure(vb,DNS_HDRSIZE+qdlen+4)) return adns_s_nomemory;
  47
  48   vb->used= 0;
  49   MKQUERY_START(vb);
  50
  51   *id_r= id= (ads->nextid++) & 0x0ffff;
  52   MKQUERY_ADDW(id);
  53   MKQUERY_ADDB(0x01); /* QR=Q(0), OPCODE=QUERY(0000), !AA, !TC, RD */
  54   MKQUERY_ADDB(0x00); /* !RA, Z=000, RCODE=NOERROR(0000) */
  55   MKQUERY_ADDW(1); /* QDCOUNT=1 */
  56   MKQUERY_ADDW(0); /* ANCOUNT=0 */
  57   MKQUERY_ADDW(0); /* NSCOUNT=0 */
  58   MKQUERY_ADDW(0); /* ARCOUNT=0 */
  59
  60   MKQUERY_STOP(vb);
  61
  62   return adns_s_ok;
  63 }
  64
  65 static adns_status mkquery_footer(vbuf *vb, adns_rrtype type) {
  66   byte *rqp;
  67
  68   MKQUERY_START(vb);
  69   MKQUERY_ADDW(type & adns_rrt_typemask); /* QTYPE */
  70   MKQUERY_ADDW(DNS_CLASS_IN); /* QCLASS=IN */
  71   MKQUERY_STOP(vb);
  72   assert(vb->used <= vb->avail);
  73
  74   return adns_s_ok;
  75 }
  76
  77 adns_status adns__mkquery(adns_state ads, vbuf *vb, int *id_r,
  78                           const char *owner, int ol,
  79                           const typeinfo *typei, adns_rrtype type,
  80                           adns_queryflags flags) {
  81   int labelnum, ll, c, nbytes;
  82   byte label[255];
  83   byte *rqp;
  84   const char *p, *pe;
  85   adns_status st;
  86
  87   st= mkquery_header(ads,vb,id_r,ol+2); if (st) return st;
  88
  89   MKQUERY_START(vb);
  90
  91   p= owner; pe= owner+ol;
  92   nbytes= 0;
  93   labelnum= 0;
  94   while (p!=pe) {
  95
  96     ll= 0;
  97     while (p!=pe && (c= *p++)!='.') {
  98       if (c=='\\') {
  99         if (ctype_digit(p[0])) {
 100           if (p+1==pe || p+2==pe) return adns_s_querydomaininvalid;
 101           if (ctype_digit(p[1]) && ctype_digit(p[2])) {
 102             c= (*p++ - '0')*100;
 103             c += (*p++ - '0')*10;
 104             c += (*p++ - '0');
 105             if (c >= 256) return adns_s_querydomaininvalid;
 106           } else {
 107             return adns_s_querydomaininvalid;
 108           }
 109         } else if (!(c= *p++)) {
 110           return adns_s_querydomaininvalid;
 111         }
 112       }
 113       if (ll >= DNS_MAXLABEL) return adns_s_querydomaintoolong;
 114       label[ll++]= c;
 115     }
 116     if (!ll) return adns_s_querydomaininvalid;
 117     nbytes+= ll+1;
 118     if (nbytes >= DNS_MAXDOMAIN) return adns_s_querydomaintoolong;
 119     MKQUERY_ADDB(ll);
 120     memcpy(rqp,label,ll); rqp+= ll;
 121   }
 122   MKQUERY_ADDB(0);
 123
 124   MKQUERY_STOP(vb);
 125
 126   st= mkquery_footer(vb,type);
 127
 128   return adns_s_ok;
 129 }
 130
 131 adns_status adns__mkquery_frdgram(adns_state ads, vbuf *vb, int *id_r,
 132                                   const byte *qd_dgram, int qd_dglen,
 133                                   int qd_begin,
 134                                   adns_rrtype type, adns_queryflags flags) {
 135   byte *rqp;
 136   findlabel_state fls;
 137   int lablen, labstart;
 138   adns_status st;
 139
 140   st= mkquery_header(ads,vb,id_r,qd_dglen); if (st) return st;
 141
 142   MKQUERY_START(vb);
 143
 144   adns__findlabel_start(&fls,ads,-1,0,qd_dgram,qd_dglen,qd_dglen,qd_begin,0);
 145   for (;;) {
 146     st= adns__findlabel_next(&fls,&lablen,&labstart); assert(!st);
 147     if (!lablen) break;
 148     assert(lablen<255);
 149     MKQUERY_ADDB(lablen);
 150     memcpy(rqp,qd_dgram+labstart,lablen);
 151     rqp+= lablen;
 152   }
 153   MKQUERY_ADDB(0);
 154
 155   MKQUERY_STOP(vb);
 156
 157   st= mkquery_footer(vb,type);
 158
 159   return adns_s_ok;
 160 }
 161
 162 void adns__querysend_tcp(adns_query qu, struct timeval now) {
 163   byte length[2];
 164   struct iovec iov[2];
 165   int wr, r;
 166   adns_state ads;
 167
 168   if (qu->ads->tcpstate != server_ok) return;
 169
 170   assert(qu->state == query_tcpw);
 171
 172   length[0]= (qu->query_dglen&0x0ff00U) >>8;
 173   length[1]= (qu->query_dglen&0x0ff);
 174
 175   ads= qu->ads;
 176   if (!adns__vbuf_ensure(&ads->tcpsend,ads->tcpsend.used+qu->query_dglen+2))
 177     return;
 178
 179   qu->retries++;
 180
 181   /* Reset idle timeout. */
 182   ads->tcptimeout.tv_sec= ads->tcptimeout.tv_usec= 0;
 183
 184   if (ads->tcpsend.used) {
 185     wr= 0;
 186   } else {
 187     iov[0].iov_base= length;
 188     iov[0].iov_len= 2;
 189     iov[1].iov_base= qu->query_dgram;
 190     iov[1].iov_len= qu->query_dglen;
 191     adns__sigpipe_protect(qu->ads);
 192     wr= writev(qu->ads->tcpsocket,iov,2);
 193     adns__sigpipe_unprotect(qu->ads);
 194     if (wr < 0) {
 195       if (!(errno == EAGAIN || errno == EINTR || errno == ENOSPC ||
 196             errno == ENOBUFS || errno == ENOMEM)) {
 197         adns__tcp_broken(ads,"write",strerror(errno));
 198         return;
 199       }
 200       wr= 0;
 201     }
 202   }
 203
 204   if (wr<2) {
 205     r= adns__vbuf_append(&ads->tcpsend,length,2-wr); assert(r);
 206     wr= 0;
 207   } else {
 208     wr-= 2;
 209   }
 210   if (wr<qu->query_dglen) {
 211     r= adns__vbuf_append(&ads->tcpsend,qu->query_dgram+wr,qu->query_dglen-wr);
 212     assert(r);
 213   }
 214 }
 215
 216 static void query_usetcp(adns_query qu, struct timeval now) {
 217   qu->state= query_tcpw;
 218   qu->timeout= now;
 219   timevaladd(&qu->timeout,TCPWAITMS);
 220   LIST_LINK_TAIL(qu->ads->tcpw,qu);
 221   adns__querysend_tcp(qu,now);
 222   adns__tcp_tryconnect(qu->ads,now);
 223 }
 224
 225 struct udpsocket *adns__udpsocket_by_af(adns_state ads, int af) {
 226   int i;
 227   for (i=0; i<ads->nudp; i++)
 228     if (ads->udpsocket[i].af == af) return &ads->udpsocket[i];
 229   return 0;
 230 }
 231
 232 void adns__query_send(adns_query qu, struct timeval now) {
 233   int serv, r, i;
 234   adns_state ads;
 235   struct udpsocket *udp;
 236   adns_rr_addr *addr;
 237
 238   assert(qu->state == query_tosend);
 239   if ((qu->flags & adns_qf_usevc) || (qu->query_dglen > DNS_MAXUDP)) {
 240     query_usetcp(qu,now);
 241     return;
 242   }
 243
 244   if (qu->retries >= UDPMAXRETRIES) {
 245     adns__query_fail(qu,adns_s_timeout);
 246     return;
 247   }
 248
 249   ads= qu->ads;
 250   serv= qu->udpnextserver;
 251   addr= &ads->servers[serv];
 252   udp= adns__udpsocket_by_af(ads, addr->addr.sa.sa_family);
 253   assert(udp);
 254
 255   r= sendto(udp->fd,qu->query_dgram,qu->query_dglen,0,
 256             &addr->addr.sa,addr->len);
 257   if (r<0 && errno == EMSGSIZE) {
 258     qu->retries= 0;
 259     query_usetcp(qu,now);
 260     return;
 261   }
 262   if (r<0 && errno != EAGAIN)
 263     adns__warn(ads,serv,0,"sendto failed: %s",strerror(errno));
 264
 265   qu->timeout= now;
 266   timevaladd(&qu->timeout,UDPRETRYMS);
 267   qu->udpsent |= (1<<serv);
 268   qu->udpnextserver= (serv+1)%ads->nservers;
 269   qu->retries++;
 270   LIST_LINK_TAIL(ads->udpw,qu);
 271 }