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) 1997-2000,2003,2006,2014-2016  Ian Jackson
   9  *    Copyright (C) 2014  Mark Wooding
  10  *    Copyright (C) 1999-2000,2003,2006  Tony Finch
  11  *    Copyright (C) 1991 Massachusetts Institute of Technology
  12  *  (See the file INSTALL for full details.)
  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 3, 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  */
  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 static adns_status qdparselabel(adns_state ads,
  78                                 const char **p_io, const char *pe,
  79                                 char label_r[], int *ll_io,
  80                                 adns_queryflags flags) {
  81   int ll, c;
  82   const char *p;
  83
  84   ll= 0;
  85   p= *p_io;
  86
  87   while (p!=pe && (c= *p++)!='.') {
  88     if (c=='\\') {
  89       if (!(flags & adns_qf_quoteok_query)) return adns_s_querydomaininvalid;
  90       if (ctype_digit(p[0])) {
  91         if (p+1==pe || p+2==pe) return adns_s_querydomaininvalid;
  92         if (ctype_digit(p[1]) && ctype_digit(p[2])) {
  93           c= (*p++ - '0')*100;
  94           c += (*p++ - '0')*10;
  95           c += (*p++ - '0');
  96           if (c >= 256) return adns_s_querydomaininvalid;
  97         } else {
  98           return adns_s_querydomaininvalid;
  99         }
 100       } else if (!(c= *p++)) {
 101         return adns_s_querydomaininvalid;
 102       }
 103     }
 104     if (ll == *ll_io) return adns_s_querydomaininvalid;
 105     label_r[ll++]= c;
 106   }
 107
 108   *p_io= p;
 109   *ll_io= ll;
 110   return adns_s_ok;
 111 }
 112
 113 adns_status adns__mkquery(adns_state ads, vbuf *vb, int *id_r,
 114                           const char *owner, int ol,
 115                           const typeinfo *typei, adns_rrtype type,
 116                           adns_queryflags flags) {
 117   int ll, nbytes;
 118   byte label[255];
 119   byte *rqp;
 120   const char *p, *pe;
 121   adns_status st;
 122
 123   st= mkquery_header(ads,vb,id_r,ol+2); if (st) return st;
 124
 125   MKQUERY_START(vb);
 126
 127   p= owner; pe= owner+ol;
 128   nbytes= 0;
 129   while (p!=pe) {
 130     ll= sizeof(label);
 131     st= qdparselabel(ads, &p,pe, label, &ll, flags);
 132     if (st) return st;
 133     if (!ll) return adns_s_querydomaininvalid;
 134     if (ll > DNS_MAXLABEL) return adns_s_querydomaintoolong;
 135     nbytes+= ll+1;
 136     if (nbytes >= DNS_MAXDOMAIN) return adns_s_querydomaintoolong;
 137     MKQUERY_ADDB(ll);
 138     memcpy(rqp,label,ll); rqp+= ll;
 139   }
 140   MKQUERY_ADDB(0);
 141
 142   MKQUERY_STOP(vb);
 143
 144   st= mkquery_footer(vb,type);
 145
 146   return adns_s_ok;
 147 }
 148
 149 adns_status adns__mkquery_frdgram(adns_state ads, vbuf *vb, int *id_r,
 150                                   const byte *qd_dgram, int qd_dglen,
 151                                   int qd_begin,
 152                                   adns_rrtype type, adns_queryflags flags) {
 153   byte *rqp;
 154   findlabel_state fls;
 155   int lablen, labstart;
 156   adns_status st;
 157
 158   st= mkquery_header(ads,vb,id_r,qd_dglen); if (st) return st;
 159
 160   MKQUERY_START(vb);
 161
 162   adns__findlabel_start(&fls,ads,-1,0,qd_dgram,qd_dglen,qd_dglen,qd_begin,0);
 163   for (;;) {
 164     st= adns__findlabel_next(&fls,&lablen,&labstart); assert(!st);
 165     if (!lablen) break;
 166     assert(lablen<255);
 167     MKQUERY_ADDB(lablen);
 168     memcpy(rqp,qd_dgram+labstart,lablen);
 169     rqp+= lablen;
 170   }
 171   MKQUERY_ADDB(0);
 172
 173   MKQUERY_STOP(vb);
 174
 175   st= mkquery_footer(vb,type);
 176
 177   return adns_s_ok;
 178 }
 179
 180 void adns__querysend_tcp(adns_query qu, struct timeval now) {
 181   byte length[2];
 182   struct iovec iov[2];
 183   int wr, r;
 184   adns_state ads;
 185
 186   if (qu->ads->tcpstate != server_ok) return;
 187
 188   assert(qu->state == query_tcpw);
 189
 190   length[0]= (qu->query_dglen&0x0ff00U) >>8;
 191   length[1]= (qu->query_dglen&0x0ff);
 192
 193   ads= qu->ads;
 194   if (!adns__vbuf_ensure(&ads->tcpsend,ads->tcpsend.used+qu->query_dglen+2))
 195     return;
 196
 197   qu->retries++;
 198
 199   /* Reset idle timeout. */
 200   ads->tcptimeout.tv_sec= ads->tcptimeout.tv_usec= 0;
 201
 202   if (ads->tcpsend.used) {
 203     wr= 0;
 204   } else {
 205     iov[0].iov_base= length;
 206     iov[0].iov_len= 2;
 207     iov[1].iov_base= qu->query_dgram;
 208     iov[1].iov_len= qu->query_dglen;
 209     adns__sigpipe_protect(qu->ads);
 210     wr= writev(qu->ads->tcpsocket,iov,2);
 211     adns__sigpipe_unprotect(qu->ads);
 212     if (wr < 0) {
 213       if (!(errno == EAGAIN || errno == EINTR || errno == ENOSPC ||
 214             errno == ENOBUFS || errno == ENOMEM)) {
 215         adns__tcp_broken(ads,"write",strerror(errno));
 216         return;
 217       }
 218       wr= 0;
 219     }
 220   }
 221
 222   if (wr<2) {
 223     r= adns__vbuf_append(&ads->tcpsend,length,2-wr); assert(r);
 224     wr= 0;
 225   } else {
 226     wr-= 2;
 227   }
 228   if (wr<qu->query_dglen) {
 229     r= adns__vbuf_append(&ads->tcpsend,qu->query_dgram+wr,qu->query_dglen-wr);
 230     assert(r);
 231   }
 232 }
 233
 234 static void query_usetcp(adns_query qu, struct timeval now) {
 235   qu->state= query_tcpw;
 236   qu->timeout= now;
 237   timevaladd(&qu->timeout,TCPWAITMS);
 238   LIST_LINK_TAIL(qu->ads->tcpw,qu);
 239   adns__querysend_tcp(qu,now);
 240   adns__tcp_tryconnect(qu->ads,now);
 241 }
 242
 243 struct udpsocket *adns__udpsocket_by_af(adns_state ads, int af) {
 244   int i;
 245   for (i=0; i<ads->nudpsockets; i++)
 246     if (ads->udpsockets[i].af == af) return &ads->udpsockets[i];
 247   return 0;
 248 }
 249
 250 void adns__query_send(adns_query qu, struct timeval now) {
 251   int serv, r;
 252   adns_state ads;
 253   struct udpsocket *udp;
 254   adns_rr_addr *addr;
 255
 256   assert(qu->state == query_tosend);
 257   if ((qu->flags & adns_qf_usevc) || (qu->query_dglen > DNS_MAXUDP)) {
 258     query_usetcp(qu,now);
 259     return;
 260   }
 261
 262   if (qu->retries >= UDPMAXRETRIES) {
 263     adns__query_fail(qu,adns_s_timeout);
 264     return;
 265   }
 266
 267   ads= qu->ads;
 268   serv= qu->udpnextserver;
 269   addr= &ads->servers[serv];
 270   udp= adns__udpsocket_by_af(ads, addr->addr.sa.sa_family);
 271   assert(udp);
 272
 273   r= sendto(udp->fd,qu->query_dgram,qu->query_dglen,0,
 274             &addr->addr.sa,addr->len);
 275   if (r<0 && errno == EMSGSIZE) {
 276     qu->retries= 0;
 277     query_usetcp(qu,now);
 278     return;
 279   }
 280   if (r<0 && errno != EAGAIN)
 281     adns__warn(ads,serv,0,"sendto failed: %s",strerror(errno));
 282
 283   qu->timeout= now;
 284   timevaladd(&qu->timeout,UDPRETRYMS);
 285   qu->udpsent |= (1<<serv);
 286   qu->udpnextserver= (serv+1)%ads->nservers;
 287   qu->retries++;
 288   LIST_LINK_TAIL(ads->udpw,qu);
 289 }