| 1 | /* |
| 2 | * event.c |
| 3 | * - event loop core |
| 4 | * - TCP connection management |
| 5 | * - user-visible check/wait and event-loop-related functions |
| 6 | */ |
| 7 | /* |
| 8 | * This file is part of adns, which is Copyright (C) 1997, 1998 Ian Jackson |
| 9 | * |
| 10 | * This program is free software; you can redistribute it and/or modify |
| 11 | * it under the terms of the GNU General Public License as published by |
| 12 | * the Free Software Foundation; either version 2, or (at your option) |
| 13 | * any later version. |
| 14 | * |
| 15 | * This program is distributed in the hope that it will be useful, |
| 16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 18 | * GNU General Public License for more details. |
| 19 | * |
| 20 | * You should have received a copy of the GNU General Public License |
| 21 | * along with this program; if not, write to the Free Software Foundation, |
| 22 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 23 | */ |
| 24 | |
| 25 | #include <string.h> |
| 26 | #include <errno.h> |
| 27 | #include <stdlib.h> |
| 28 | |
| 29 | #include <netdb.h> |
| 30 | #include <arpa/inet.h> |
| 31 | |
| 32 | #include "internal.h" |
| 33 | |
| 34 | /* TCP connection management */ |
| 35 | |
| 36 | void adns__tcp_broken(adns_state ads, const char *what, const char *why) { |
| 37 | int serv; |
| 38 | adns_query qu, nqu; |
| 39 | |
| 40 | assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok); |
| 41 | serv= ads->tcpserver; |
| 42 | adns__warn(ads,serv,0,"TCP connection lost: %s: %s",what,why); |
| 43 | close(ads->tcpsocket); |
| 44 | ads->tcpstate= server_disconnected; |
| 45 | |
| 46 | for (qu= ads->timew.head; qu; qu= nqu) { |
| 47 | nqu= qu->next; |
| 48 | if (qu->state == query_udp) continue; |
| 49 | assert(qu->state == query_tcpwait || qu->state == query_tcpsent); |
| 50 | qu->state= query_tcpwait; |
| 51 | qu->tcpfailed |= (1<<serv); |
| 52 | if (qu->tcpfailed == (1<<ads->nservers)-1) { |
| 53 | LIST_UNLINK(ads->timew,qu); |
| 54 | adns__query_fail(qu,adns_s_allservfail); |
| 55 | } |
| 56 | } |
| 57 | |
| 58 | ads->tcprecv.used= ads->tcpsend.used= 0; |
| 59 | ads->tcpserver= (serv+1)%ads->nservers; |
| 60 | } |
| 61 | |
| 62 | static void tcp_connected(adns_state ads, struct timeval now) { |
| 63 | adns_query qu, nqu; |
| 64 | |
| 65 | adns__debug(ads,ads->tcpserver,0,"TCP connected"); |
| 66 | ads->tcpstate= server_ok; |
| 67 | for (qu= ads->timew.head; qu; qu= nqu) { |
| 68 | nqu= qu->next; |
| 69 | if (qu->state == query_udp) continue; |
| 70 | assert (qu->state == query_tcpwait); |
| 71 | adns__query_tcp(qu,now); |
| 72 | } |
| 73 | } |
| 74 | |
| 75 | void adns__tcp_tryconnect(adns_state ads, struct timeval now) { |
| 76 | int r, fd, tries; |
| 77 | struct sockaddr_in addr; |
| 78 | struct protoent *proto; |
| 79 | |
| 80 | for (tries=0; tries<ads->nservers; tries++) { |
| 81 | if (ads->tcpstate == server_connecting || ads->tcpstate == server_ok) return; |
| 82 | assert(ads->tcpstate == server_disconnected); |
| 83 | assert(!ads->tcpsend.used); |
| 84 | assert(!ads->tcprecv.used); |
| 85 | |
| 86 | proto= getprotobyname("tcp"); |
| 87 | if (!proto) { adns__diag(ads,-1,0,"unable to find protocol no. for TCP !"); return; } |
| 88 | fd= socket(AF_INET,SOCK_STREAM,proto->p_proto); |
| 89 | if (fd<0) { |
| 90 | adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno)); |
| 91 | return; |
| 92 | } |
| 93 | r= adns__setnonblock(ads,fd); |
| 94 | if (r) { |
| 95 | adns__diag(ads,-1,0,"cannot make TCP socket nonblocking: %s",strerror(r)); |
| 96 | close(fd); |
| 97 | return; |
| 98 | } |
| 99 | memset(&addr,0,sizeof(addr)); |
| 100 | addr.sin_family= AF_INET; |
| 101 | addr.sin_port= htons(DNS_PORT); |
| 102 | addr.sin_addr= ads->servers[ads->tcpserver].addr; |
| 103 | r= connect(fd,&addr,sizeof(addr)); |
| 104 | ads->tcpsocket= fd; |
| 105 | ads->tcpstate= server_connecting; |
| 106 | if (r==0) { tcp_connected(ads,now); continue; } |
| 107 | if (errno == EWOULDBLOCK || errno == EINPROGRESS) return; |
| 108 | adns__tcp_broken(ads,"connect",strerror(errno)); |
| 109 | } |
| 110 | } |
| 111 | |
| 112 | /* `Interest' functions - find out which fd's we might be interested in, |
| 113 | * and when we want to be called back for a timeout. |
| 114 | */ |
| 115 | |
| 116 | static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf, |
| 117 | struct timeval maxto) { |
| 118 | struct timeval *rbuf; |
| 119 | |
| 120 | if (!tv_io) return; |
| 121 | rbuf= *tv_io; |
| 122 | if (!rbuf) { |
| 123 | *tvbuf= maxto; *tv_io= tvbuf; |
| 124 | } else { |
| 125 | if (timercmp(rbuf,&maxto,>)) *rbuf= maxto; |
| 126 | } |
| 127 | /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n", |
| 128 | maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/ |
| 129 | } |
| 130 | |
| 131 | static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf, |
| 132 | struct timeval now, struct timeval maxtime) { |
| 133 | ldiv_t dr; |
| 134 | |
| 135 | /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n", |
| 136 | now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/ |
| 137 | if (!tv_io) return; |
| 138 | maxtime.tv_sec -= (now.tv_sec+2); |
| 139 | maxtime.tv_usec -= (now.tv_usec-2000000); |
| 140 | dr= ldiv(maxtime.tv_usec,1000000); |
| 141 | maxtime.tv_sec += dr.quot; |
| 142 | maxtime.tv_usec -= dr.quot*1000000; |
| 143 | if (maxtime.tv_sec<0) timerclear(&maxtime); |
| 144 | inter_maxto(tv_io,tvbuf,maxtime); |
| 145 | } |
| 146 | |
| 147 | static void inter_addfd(int *maxfd, fd_set *fds, int fd) { |
| 148 | if (!maxfd || !fds) return; |
| 149 | if (fd>=*maxfd) *maxfd= fd+1; |
| 150 | FD_SET(fd,fds); |
| 151 | } |
| 152 | |
| 153 | static void checktimeouts(adns_state ads, struct timeval now, |
| 154 | struct timeval **tv_io, struct timeval *tvbuf) { |
| 155 | adns_query qu, nqu; |
| 156 | |
| 157 | for (qu= ads->timew.head; qu; qu= nqu) { |
| 158 | nqu= qu->next; |
| 159 | if (timercmp(&now,&qu->timeout,>)) { |
| 160 | LIST_UNLINK(ads->timew,qu); |
| 161 | if (qu->state != query_udp) { |
| 162 | adns__query_fail(qu,adns_s_timeout); |
| 163 | } else { |
| 164 | adns__query_udp(qu,now); |
| 165 | } |
| 166 | } else { |
| 167 | inter_maxtoabs(tv_io,tvbuf,now,qu->timeout); |
| 168 | } |
| 169 | } |
| 170 | } |
| 171 | |
| 172 | void adns_interest(adns_state ads, int *maxfd, |
| 173 | fd_set *readfds, fd_set *writefds, fd_set *exceptfds, |
| 174 | struct timeval **tv_io, struct timeval *tvbuf) { |
| 175 | struct timeval now; |
| 176 | struct timeval tvto_lr; |
| 177 | int r; |
| 178 | |
| 179 | /*fprintf(stderr,"adns_interest\n");*/ |
| 180 | |
| 181 | r= gettimeofday(&now,0); |
| 182 | if (r) { |
| 183 | adns__warn(ads,-1,0,"gettimeofday failed - will sleep for a bit: %s", |
| 184 | strerror(errno)); |
| 185 | timerclear(&tvto_lr); timevaladd(&tvto_lr,LOCALRESOURCEMS); |
| 186 | inter_maxto(tv_io, tvbuf, tvto_lr); |
| 187 | } else { |
| 188 | checktimeouts(ads,now,tv_io,tvbuf); |
| 189 | } |
| 190 | |
| 191 | inter_addfd(maxfd,readfds,ads->udpsocket); |
| 192 | |
| 193 | switch (ads->tcpstate) { |
| 194 | case server_disconnected: |
| 195 | break; |
| 196 | case server_connecting: |
| 197 | inter_addfd(maxfd,writefds,ads->tcpsocket); |
| 198 | break; |
| 199 | case server_ok: |
| 200 | inter_addfd(maxfd,readfds,ads->tcpsocket); |
| 201 | inter_addfd(maxfd,exceptfds,ads->tcpsocket); |
| 202 | if (ads->tcpsend.used) inter_addfd(maxfd,writefds,ads->tcpsocket); |
| 203 | break; |
| 204 | default: |
| 205 | abort(); |
| 206 | } |
| 207 | } |
| 208 | |
| 209 | /* Callback procedures - these do the real work of reception and timeout, etc. */ |
| 210 | |
| 211 | static int callb_checkfd(int maxfd, const fd_set *fds, int fd) { |
| 212 | return maxfd<0 || !fds ? 1 : |
| 213 | fd<maxfd && FD_ISSET(fd,fds); |
| 214 | } |
| 215 | |
| 216 | static int internal_callback(adns_state ads, int maxfd, |
| 217 | const fd_set *readfds, const fd_set *writefds, |
| 218 | const fd_set *exceptfds, |
| 219 | struct timeval now) { |
| 220 | int skip, want, dgramlen, count, udpaddrlen, r, serv; |
| 221 | byte udpbuf[DNS_MAXUDP]; |
| 222 | struct sockaddr_in udpaddr; |
| 223 | |
| 224 | count= 0; |
| 225 | |
| 226 | switch (ads->tcpstate) { |
| 227 | case server_disconnected: |
| 228 | break; |
| 229 | case server_connecting: |
| 230 | if (callb_checkfd(maxfd,writefds,ads->tcpsocket)) { |
| 231 | count++; |
| 232 | assert(ads->tcprecv.used==0); |
| 233 | if (!adns__vbuf_ensure(&ads->tcprecv,1)) return -1; |
| 234 | if (ads->tcprecv.buf) { |
| 235 | r= read(ads->tcpsocket,&ads->tcprecv.buf,1); |
| 236 | if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) { |
| 237 | tcp_connected(ads,now); |
| 238 | } else if (r>0) { |
| 239 | adns__tcp_broken(ads,"connect/read","sent data before first request"); |
| 240 | } else if (errno!=EINTR) { |
| 241 | adns__tcp_broken(ads,"connect/read",strerror(errno)); |
| 242 | } |
| 243 | } |
| 244 | } |
| 245 | break; |
| 246 | case server_ok: |
| 247 | count+= callb_checkfd(maxfd,readfds,ads->tcpsocket) + |
| 248 | callb_checkfd(maxfd,exceptfds,ads->tcpsocket) + |
| 249 | (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket)); |
| 250 | if (callb_checkfd(maxfd,readfds,ads->tcpsocket)) { |
| 251 | skip= 0; |
| 252 | for (;;) { |
| 253 | if (ads->tcprecv.used<skip+2) { |
| 254 | want= 2; |
| 255 | } else { |
| 256 | dgramlen= (ads->tcprecv.buf[skip]<<8) | ads->tcprecv.buf[skip+1]; |
| 257 | if (ads->tcprecv.used<skip+2+dgramlen) { |
| 258 | want= 2+dgramlen; |
| 259 | } else { |
| 260 | adns__procdgram(ads,ads->tcprecv.buf+skip+2,dgramlen,ads->tcpserver,now); |
| 261 | skip+= 2+dgramlen; continue; |
| 262 | } |
| 263 | } |
| 264 | ads->tcprecv.used -= skip; |
| 265 | memmove(ads->tcprecv.buf,ads->tcprecv.buf+skip,ads->tcprecv.used); |
| 266 | skip= 0; |
| 267 | if (!adns__vbuf_ensure(&ads->tcprecv,want)) return -1; |
| 268 | assert(ads->tcprecv.used <= ads->tcprecv.avail); |
| 269 | if (ads->tcprecv.used == ads->tcprecv.avail) continue; |
| 270 | r= read(ads->tcpsocket, |
| 271 | ads->tcprecv.buf+ads->tcprecv.used, |
| 272 | ads->tcprecv.avail-ads->tcprecv.used); |
| 273 | if (r>0) { |
| 274 | ads->tcprecv.used+= r; |
| 275 | } else { |
| 276 | if (r<0) { |
| 277 | if (errno==EAGAIN || errno==EWOULDBLOCK || errno==ENOMEM) break; |
| 278 | if (errno==EINTR) continue; |
| 279 | } |
| 280 | adns__tcp_broken(ads,"read",r?strerror(errno):"closed"); |
| 281 | break; |
| 282 | } |
| 283 | } |
| 284 | } else if (callb_checkfd(maxfd,exceptfds,ads->tcpsocket)) { |
| 285 | adns__tcp_broken(ads,"select","exceptional condition detected"); |
| 286 | } else if (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket)) { |
| 287 | r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used); |
| 288 | if (r<0) { |
| 289 | if (errno!=EAGAIN && errno!=EWOULDBLOCK && errno!=ENOMEM && errno!=EINTR) { |
| 290 | adns__tcp_broken(ads,"write",strerror(errno)); |
| 291 | } |
| 292 | } else if (r>0) { |
| 293 | ads->tcpsend.used -= r; |
| 294 | memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used); |
| 295 | } |
| 296 | } |
| 297 | break; |
| 298 | default: |
| 299 | abort(); |
| 300 | } |
| 301 | |
| 302 | if (callb_checkfd(maxfd,readfds,ads->udpsocket)) { |
| 303 | count++; |
| 304 | for (;;) { |
| 305 | udpaddrlen= sizeof(udpaddr); |
| 306 | r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,&udpaddr,&udpaddrlen); |
| 307 | if (r<0) { |
| 308 | if (!(errno == EAGAIN || errno == EWOULDBLOCK || |
| 309 | errno == EINTR || errno == ENOMEM || errno == ENOBUFS)) |
| 310 | adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno)); |
| 311 | break; |
| 312 | } |
| 313 | if (udpaddrlen != sizeof(udpaddr)) { |
| 314 | adns__diag(ads,-1,0,"datagram received with wrong address length %d" |
| 315 | " (expected %d)", udpaddrlen,sizeof(udpaddr)); |
| 316 | continue; |
| 317 | } |
| 318 | if (udpaddr.sin_family != AF_INET) { |
| 319 | adns__diag(ads,-1,0,"datagram received with wrong protocol family" |
| 320 | " %u (expected %u)",udpaddr.sin_family,AF_INET); |
| 321 | continue; |
| 322 | } |
| 323 | if (ntohs(udpaddr.sin_port) != DNS_PORT) { |
| 324 | adns__diag(ads,-1,0,"datagram received from wrong port %u (expected %u)", |
| 325 | ntohs(udpaddr.sin_port),DNS_PORT); |
| 326 | continue; |
| 327 | } |
| 328 | for (serv= 0; |
| 329 | serv < ads->nservers && |
| 330 | ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr; |
| 331 | serv++); |
| 332 | if (serv >= ads->nservers) { |
| 333 | adns__warn(ads,-1,0,"datagram received from unknown nameserver %s", |
| 334 | inet_ntoa(udpaddr.sin_addr)); |
| 335 | continue; |
| 336 | } |
| 337 | adns__procdgram(ads,udpbuf,r,serv,now); |
| 338 | } |
| 339 | } |
| 340 | return count; |
| 341 | } |
| 342 | |
| 343 | int adns_callback(adns_state ads, int maxfd, |
| 344 | const fd_set *readfds, const fd_set *writefds, |
| 345 | const fd_set *exceptfds) { |
| 346 | struct timeval now; |
| 347 | int r; |
| 348 | |
| 349 | r= gettimeofday(&now,0); if (r) return -1; |
| 350 | checktimeouts(ads,now,0,0); |
| 351 | return internal_callback(ads,maxfd,readfds,writefds,exceptfds,now); |
| 352 | } |
| 353 | |
| 354 | /* User-visible functions and their implementation. */ |
| 355 | |
| 356 | void adns__autosys(adns_state ads, struct timeval now) { |
| 357 | if (ads->iflags & adns_if_noautosys) return; |
| 358 | adns_callback(ads,-1,0,0,0); |
| 359 | } |
| 360 | |
| 361 | static int internal_check(adns_state ads, |
| 362 | adns_query *query_io, |
| 363 | adns_answer **answer, |
| 364 | void **context_r) { |
| 365 | adns_query qu; |
| 366 | |
| 367 | qu= *query_io; |
| 368 | if (!qu) { |
| 369 | if (!ads->output.head) return EWOULDBLOCK; |
| 370 | qu= ads->output.head; |
| 371 | } else { |
| 372 | if (qu->id>=0) return EWOULDBLOCK; |
| 373 | } |
| 374 | LIST_UNLINK(ads->output,qu); |
| 375 | *answer= qu->answer; |
| 376 | if (context_r) *context_r= qu->ctx.ext; |
| 377 | free(qu); |
| 378 | return 0; |
| 379 | } |
| 380 | |
| 381 | int adns_wait(adns_state ads, |
| 382 | adns_query *query_io, |
| 383 | adns_answer **answer_r, |
| 384 | void **context_r) { |
| 385 | int r, maxfd, rsel, rcb; |
| 386 | fd_set readfds, writefds, exceptfds; |
| 387 | struct timeval tvbuf, *tvp; |
| 388 | |
| 389 | for (;;) { |
| 390 | r= internal_check(ads,query_io,answer_r,context_r); |
| 391 | if (r != EWOULDBLOCK) return r; |
| 392 | maxfd= 0; tvp= 0; |
| 393 | FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds); |
| 394 | adns_interest(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf); |
| 395 | rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp); |
| 396 | if (rsel==-1) { |
| 397 | if (errno == EINTR && !(ads->iflags & adns_if_eintr)) continue; |
| 398 | return errno; |
| 399 | } |
| 400 | rcb= adns_callback(ads,maxfd,&readfds,&writefds,&exceptfds); |
| 401 | assert(rcb==rsel); |
| 402 | } |
| 403 | } |
| 404 | |
| 405 | int adns_check(adns_state ads, |
| 406 | adns_query *query_io, |
| 407 | adns_answer **answer_r, |
| 408 | void **context_r) { |
| 409 | struct timeval now; |
| 410 | int r; |
| 411 | |
| 412 | r= gettimeofday(&now,0); if (r) return errno; |
| 413 | adns__autosys(ads,now); |
| 414 | return internal_check(ads,query_io,answer_r,context_r); |
| 415 | } |