mdw@git.distorted.org.uk Git - fwd/blob - socket.c

   1 /* -*-c-*-
   2  *
   3  * $Id: socket.c,v 1.1 1999/07/26 23:33:32 mdw Exp $
   4  *
   5  * Socket source and target definitions
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of the `fw' port forwarder.
  13  *
  14  * `fw' 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 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * `fw' 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 `fw'; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: socket.c,v $
  32  * Revision 1.1  1999/07/26 23:33:32  mdw
  33  * New sources and targets.
  34  *
  35  */
  36
  37 /*----- Header files ------------------------------------------------------*/
  38
  39 #include "config.h"
  40
  41 #include <ctype.h>
  42 #include <errno.h>
  43 #include <stdio.h>
  44 #include <stdlib.h>
  45 #include <string.h>
  46
  47 #include <sys/socket.h>
  48 #include <netinet/in.h>
  49 #include <arpa/inet.h>
  50 #include <netdb.h>
  51
  52 #include <mLib/alloc.h>
  53 #include <mLib/conn.h>
  54 #include <mLib/dstr.h>
  55 #include <mLib/fdflags.h>
  56 #include <mLib/sel.h>
  57 #include <mLib/sub.h>
  58
  59 #include "addr.h"
  60 #include "conf.h"
  61 #include "endpt.h"
  62 #include "fw.h"
  63 #include "scan.h"
  64 #include "socket.h"
  65 #include "target.h"
  66
  67 #include "inet.h"
  68 #include "un.h"
  69
  70 /*----- Data structures ---------------------------------------------------*/
  71
  72 /* --- Socket source options --- */
  73
  74 typedef struct ssource_opts {
  75   unsigned conn;
  76 } ssource_opts;
  77
  78 static ssource_opts ssgo = { 256 };
  79
  80 /* --- Socket source --- */
  81
  82 typedef struct ssource {
  83   source s;
  84   addr *a;
  85   target *t;
  86   addr_opts *ao;
  87   ssource_opts o;
  88   sel_file r;
  89 } ssource;
  90
  91 /* --- Socket target --- */
  92
  93 typedef struct starget {
  94   target t;
  95   addr *a;
  96   addr_opts *ao;
  97 } starget;
  98
  99 /* --- Socket target endpoint --- */
 100
 101 typedef struct stept {
 102   endpt e;
 103   conn c;
 104   const char *desc;
 105 } stept;
 106
 107 /* --- Socket source endpoint --- */
 108
 109 typedef struct ssept {
 110   endpt e;
 111   ssource *s;
 112 } ssept;
 113
 114 #define SKF_CONN 16u
 115 #define SKF_BROKEN 32u
 116
 117 /*----- Protocol table ----------------------------------------------------*/
 118
 119 static addr_ops *addrs[] = { &inet_ops, &un_ops, 0 };
 120
 121 /*----- Other persistent variables ----------------------------------------*/
 122
 123 static addr_opts gao = { 0 };
 124
 125 /*----- Parsing address types ---------------------------------------------*/
 126
 127 /* --- @getaddrtype@ --- *
 128  *
 129  * Arguments:   @scanner *sc@ = pointer to scanner (for error reporting)
 130  *              @const char *p@ = pointer to protocol name
 131  *              @int abbrev@ = nonzero to allow abbreviations
 132  *
 133  * Returns:     Pointer to address operations table or null.
 134  *
 135  * Use:         Looks up a protocol name.  Handy when parsing addresses and
 136  *              other bits of configuration.  Returns null if no matching
 137  *              address was found.
 138  */
 139
 140 static addr_ops *getaddrtype(scanner *sc, const char *p, int abbrev)
 141 {
 142   addr_ops **ops;
 143   addr_ops *chosen = 0;
 144   size_t sz = strlen(p);
 145
 146   for (ops = addrs; *ops; ops++) {
 147     if (strncmp((*ops)->name, p, sz) == 0) {
 148       if ((*ops)->name[sz] == 0)
 149         return (*ops);
 150       else if (chosen && abbrev)
 151         error(sc, "ambiguous socket address type `%s'", p);
 152       chosen = *ops;
 153     }
 154   }
 155   if (!abbrev)
 156     return (0);
 157   return (chosen);
 158 }
 159
 160 /* --- @getaddr@ --- *
 161  *
 162  * Arguments:   @scanner *sc@ = pointer to scanner to read from
 163  *              @unsigned type@ = address type (@ADDR_SRC@ or @ADDR_DEST@)
 164  *
 165  * Returns:     Pointer to an address successfully read.
 166  *
 167  * Use:         Reads an optionally qualified address.
 168  */
 169
 170 static addr *getaddr(scanner *sc, unsigned type)
 171 {
 172   addr_ops *ops = 0;
 173   int abbrev = 0;
 174
 175   if (sc->t == ':') {
 176     token(sc);
 177     abbrev = 1;
 178   }
 179   if (sc->t == CTOK_WORD)
 180     ops = getaddrtype(sc, sc->d.buf, abbrev);
 181   if (ops)
 182     token(sc);
 183   else if (abbrev)
 184     error(sc, "unknown socket address type `%s'", sc->d.buf);
 185   else
 186     ops = &inet_ops;
 187   if (sc->t == ':')
 188     token(sc);
 189
 190   return (ops->read(sc, type));
 191 }
 192
 193 /*----- Socket endpoints --------------------------------------------------*/
 194
 195 /* --- @wclose@ --- */
 196
 197 static void sept_wclose(endpt *e)
 198 {
 199   shutdown(e->out->fd, 1);
 200 }
 201
 202 /* --- @close@ (source) --- */
 203
 204 static void ss_listen(ssource */*ss*/);
 205
 206 static void ssept_close(endpt *e)
 207 {
 208   ssept *ee = (ssept *)e;
 209
 210   if (!ee->s->o.conn) {
 211     ee->s->o.conn++;
 212     ss_listen(ee->s);
 213   } else
 214     ee->s->o.conn++;
 215   REFFD_DEC(ee->e.in);
 216   REFFD_DEC(ee->e.out);
 217   fw_dec();
 218   DESTROY(ee);
 219 }
 220
 221 /* --- @close@ (target) --- */
 222
 223 static void stept_close(endpt *e)
 224 {
 225   stept *ee = (stept *)e;
 226
 227   if (ee->e.f & EPF_PENDING) {
 228     if (ee->e.f & SKF_CONN)
 229       conn_kill(&ee->c);
 230   } else {
 231     REFFD_DEC(ee->e.in);
 232     REFFD_DEC(ee->e.out);
 233   }
 234
 235   fw_dec();
 236   DESTROY(ee);
 237 }
 238
 239 /* --- @stept_go@ --- *
 240  *
 241  * Arguments:   @int fd@ = file descriptor now ready for use
 242  *              @void *p@ = pointer to an endpoint structure
 243  *
 244  * Returns:     ---
 245  *
 246  * Use:         Handles successful connection of the target endpoint.
 247  */
 248
 249 static void stept_go(int fd, void *p)
 250 {
 251   stept *e = p;
 252
 253   /* --- Complicated and subtle --- *
 254    *
 255    * This code interacts quite closely with @starget_create@, mainly through
 256    * flags in the endpoint block.
 257    *
 258    * If the connection failed, I log a message (that's easy enough).  The
 259    * behaviour then depends on whether the endpoints have been joined yet.
 260    * If not, I set @SKF_BROKEN@ and return, so that @starget_create@ can
 261    * clean up the mess and return an immediate failure.  If they have, I kill
 262    * the connection and everything ought to work.
 263    *
 264    * If the connection worked, I clear @EPF_PENDING@ (as expected, because
 265    * my endpoint is now ready), and @SKF_CONN@ (to let @starget_create@ know
 266    * that the connection is already going).  Then, only if this isn't the
 267    * first attempt, I rejoin this endpoint to its partner.
 268    */
 269
 270   if (fd == -1) {
 271     fw_log(-1, "[%s] connection failed: %s", e->desc, strerror(errno));
 272     e->e.f &= ~SKF_CONN;
 273     if (e->e.f & EPF_PENDING)
 274       endpt_kill(&e->e);
 275     else
 276       e->e.f |= SKF_BROKEN;
 277   } else {
 278     reffd *r = reffd_init(fd);
 279     REFFD_INC(r);
 280     e->e.in = e->e.out = r;
 281     e->e.f &= ~(EPF_PENDING | SKF_CONN);
 282     if (e->e.other)
 283       endpt_join(&e->e, e->e.other);
 284   }
 285 }
 286
 287 /* --- Socket endpoint definition --- */
 288
 289 static endpt_ops ssept_ops = {
 290   0, sept_wclose, ssept_close
 291 };
 292
 293 static endpt_ops stept_ops = {
 294   0, sept_wclose, stept_close
 295 };
 296
 297 /*----- Source definition -------------------------------------------------*/
 298
 299 /* --- @option@ --- */
 300
 301 static int ssource_option(source *s, scanner *sc)
 302 {
 303   ssource *ss = (ssource *)s;
 304   ssource_opts *sso = ss ? &ss->o : &ssgo;
 305
 306   CONF_BEGIN(sc, "socket", "socket")
 307
 308   /* --- Make sure the next token is a word --- */
 309
 310   if (sc->t != CTOK_WORD)
 311     error(sc, "parse error, option keyword expected");
 312
 313   /* --- Handle options at this level --- */
 314
 315   if (strcmp(sc->d.buf, "conn") == 0) {
 316     token(sc);
 317     if (sc->t == '=')
 318       token(sc);
 319     if (sc->t != CTOK_WORD || !isdigit((unsigned char)sc->d.buf[0]))
 320       error(sc, "parse error, argument of `conn' must be a number");
 321     sso->conn = atoi(sc->d.buf);
 322     if (sso->conn == 0)
 323       error(sc, "argument of `conn' must be positive");
 324     token(sc);
 325     CONF_ACCEPT;
 326   }
 327
 328   if (strcmp(sc->d.buf, "logging") == 0 ||
 329       strcmp(sc->d.buf, "log") == 0) {
 330     addr_opts *ao = ss ? ss->ao : &gao;
 331     token(sc);
 332     if (sc->t == '=')
 333       token(sc);
 334     if (conf_enum(sc, "no,yes", ENUM_ABBREV, "logging status"))
 335       ao->f &= ~ADDRF_NOLOG;
 336     else
 337       ao->f |= ADDRF_NOLOG;
 338     CONF_ACCEPT;
 339   }
 340
 341   /* --- Pass the option around the various address types --- */
 342
 343   if (ss) {
 344     if (ss->a->ops->option && ss->a->ops->option(sc, ss ? ss->ao : 0))
 345       CONF_ACCEPT;
 346   } else {
 347     addr_ops **a;
 348     for (a = addrs; *a; a++) {
 349       if ((*a)->option && (*a)->option(sc, 0))
 350         CONF_ACCEPT;
 351     }
 352   }
 353
 354   /* --- Nobody understood the option --- */
 355
 356   CONF_END;
 357 }
 358
 359 /* --- @read@ --- */
 360
 361 static source *ssource_read(scanner *sc)
 362 {
 363   ssource *ss;
 364
 365   (void)(conf_prefix(sc, "socket") || conf_prefix(sc, "sk"));
 366   ss = CREATE(ssource);
 367   ss->s.ops = &ssource_ops;
 368   ss->s.desc = 0;
 369   ss->t = 0;
 370   ss->a = getaddr(sc, ADDR_SRC);
 371   if (ss->a->ops->initopts)
 372     ss->ao = ss->a->ops->initopts();
 373   else
 374     ss->ao = CREATE(addr_opts);
 375   *ss->ao = gao;
 376   ss->o = ssgo;
 377   return (&ss->s);
 378 }
 379
 380 /* --- @ss_accept@ --- *
 381  *
 382  * Arguments:   @int fd@ = file descriptor to accept from
 383  *              @unsigned mode@ = what's ready with the descriptor
 384  *              @void *p@ = pointer to the source definition
 385  *
 386  * Returns:     ---
 387  *
 388  * Use:         Accepts an incoming connection and attaches it to a target
 389  *              endpoint.
 390  */
 391
 392 static void ss_accept(int fd, unsigned mode, void *p)
 393 {
 394   ssource *ss = p;
 395   ssept *e;
 396   endpt *ee;
 397   reffd *r;
 398
 399   /* --- Make the file descriptor --- */
 400
 401   {
 402     int opt = 1;
 403     if ((r = ss->a->ops->accept(fd, ss->ao, ss->s.desc)) == 0)
 404       return;
 405     setsockopt(r->fd, SOL_SOCKET, SO_OOBINLINE, &opt, sizeof(opt));
 406     fdflags(r->fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 407   }
 408
 409   /* --- Make an endpoint --- */
 410
 411   e = CREATE(ssept);
 412   e->e.ops = &ssept_ops;
 413   e->e.other = 0;
 414   e->e.f = EPF_FILE;
 415   e->e.t = 0;
 416   e->e.in = e->e.out = r;
 417   e->s = ss;
 418   REFFD_INC(r);
 419
 420   /* --- Obtain the target endpoint and let rip --- */
 421
 422   if ((ee = ss->t->ops->create(ss->t, ss->s.desc)) == 0) {
 423     REFFD_DEC(r);
 424     REFFD_DEC(r);
 425     DESTROY(e);
 426     return;
 427   }
 428
 429   /* --- Remove the listening socket if necessary --- */
 430
 431   ss->o.conn--;
 432   if (!ss->o.conn) {
 433     fw_log(-1, "[%s] maximum connections reached", ss->s.desc);
 434     sel_rmfile(&ss->r);
 435     close(ss->r.fd);
 436     if (ss->a->ops->unbind)
 437       ss->a->ops->unbind(ss->a);
 438   }
 439
 440   /* --- Let everything else happen --- */
 441
 442   fw_inc();
 443   endpt_join(&e->e, ee);
 444 }
 445
 446 /* --- @ss_listen@ --- *
 447  *
 448  * Arguments:   @ssource *ss@ = source to listen on
 449  *
 450  * Returns:     ---
 451  *
 452  * Use:         Sets the socket to listen again, if it stopped for some
 453  *              reason.  This is a copy of the code in the @read@ function,
 454  *              because it has different (wildly different) error handling
 455  *              behaviour.
 456  */
 457
 458 static void ssource_destroy(source */*s*/);
 459
 460 static void ss_listen(ssource *ss)
 461 {
 462   gen_addr *ga = (gen_addr *)ss->a;
 463   int fd;
 464
 465   fw_log(-1, "[%s] reattaching listener", ss->s.desc);
 466
 467   /* --- Make the socket --- */
 468
 469   if ((fd = socket(ga->a.ops->pf, SOCK_STREAM, 0)) < 0) {
 470     fw_log(-1, "[%s] couldn't create socket: %s",
 471            ss->s.desc, strerror(errno));
 472     goto fail_0;
 473   }
 474
 475   /* --- Set it to allow address reuse --- */
 476
 477   {
 478     int opt = 1;
 479     setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
 480     fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 481   }
 482
 483   /* --- Bind it to the right port --- */
 484
 485   if (bind(fd, &ga->sa, ga->a.sz)) {
 486     fw_log(-1, "[%s] couldn't bind to %s: %s", ss->s.desc, strerror(errno));
 487     goto fail_1;
 488   }
 489   if (ga->a.ops->bound)
 490     ga->a.ops->bound(&ga->a, ss->ao);
 491
 492   /* --- Set it to listen for connections --- */
 493
 494   if (listen(fd, 5)) {
 495     fw_log(-1, "[%s] couldn't listen on socket: %s",
 496            ss->s.desc, strerror(errno));
 497     goto fail_1;
 498   }
 499
 500   /* --- Set the listener up again --- */
 501
 502   ss->r.fd = fd;
 503   sel_addfile(&ss->r);
 504   return;
 505
 506   /* --- Tidy up if it failed --- *
 507    *
 508    * I'll just remove the entire source.
 509    */
 510
 511 fail_1:
 512   close(fd);
 513 fail_0:
 514   ss->o.conn = 0;
 515   ssource_destroy(&ss->s);
 516 }
 517
 518 /* --- @attach@ --- */
 519
 520 static void ssource_attach(source *s, scanner *sc, target *t)
 521 {
 522   ssource *ss = (ssource *)s;
 523   int fd;
 524
 525   ss->t = t;
 526
 527   /* --- Initialize the description string --- */
 528
 529   {
 530     dstr d = DSTR_INIT;
 531     dstr_puts(&d, "socket.");
 532     ss->a->ops->print(ss->a, ADDR_SRC, &d);
 533     dstr_puts(&d, " -> ");
 534     dstr_puts(&d, ss->t->desc);
 535     ss->s.desc = xstrdup(d.buf);
 536     dstr_destroy(&d);
 537   }
 538
 539   /* --- Initialize the socket for listening --- */
 540
 541   {
 542     gen_addr *ga = (gen_addr *)ss->a;
 543
 544     /* --- Make the socket --- */
 545
 546     if ((fd = socket(ga->a.ops->pf, SOCK_STREAM, 0)) < 0)
 547       error(sc, "couldn't create socket: %s", strerror(errno));
 548
 549     /* --- Set it to allow address reuse --- */
 550
 551     {
 552       int opt = 1;
 553       setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
 554       fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 555     }
 556
 557     /* --- Bind it to the right port --- */
 558
 559     if (bind(fd, &ga->sa, ga->a.sz))
 560       error(sc, "couldn't bind to %s: %s", ss->s.desc, strerror(errno));
 561     if (ga->a.ops->bound)
 562       ga->a.ops->bound(&ga->a, ss->ao);
 563
 564     /* --- Set it to listen for connections --- */
 565
 566     if (listen(fd, 5))
 567       error(sc, "couldn't listen on socket: %s", strerror(errno));
 568   }
 569
 570   /* --- We're ready to go now --- */
 571
 572   sel_initfile(sel, &ss->r, fd, SEL_READ, ss_accept, ss);
 573   sel_addfile(&ss->r);
 574   source_add(&ss->s);
 575   fw_inc();
 576 }
 577
 578 /* --- @destroy@ --- */
 579
 580 static void ssource_destroy(source *s)
 581 {
 582   ssource *ss = (ssource *)s;
 583
 584   if (ss->o.conn) {
 585     sel_rmfile(&ss->r);
 586     close(ss->r.fd);
 587     if (ss->a->ops->unbind)
 588       ss->a->ops->unbind(ss->a);
 589   }
 590   if (ss->a->ops->freeopts)
 591     ss->a->ops->freeopts(ss->ao);
 592   else
 593     DESTROY(ss->ao);
 594   /* free(ss->s.desc); */
 595   ss->a->ops->destroy(ss->a);
 596   ss->t->ops->destroy(ss->t);
 597   source_remove(&ss->s);
 598   DESTROY(ss);
 599   fw_dec();
 600 }
 601
 602 /* --- Source definition block --- */
 603
 604 source_ops ssource_ops = {
 605   "socket",
 606   ssource_option, ssource_read, ssource_attach, ssource_destroy
 607 };
 608
 609 /*----- Target definition -------------------------------------------------*/
 610
 611 /* --- @read@ --- */
 612
 613 static target *starget_read(scanner *sc)
 614 {
 615   starget *st;
 616   dstr d = DSTR_INIT;
 617
 618   (void)(conf_prefix(sc, "socket") || conf_prefix(sc, "sk"));
 619   st = CREATE(starget);
 620   st->t.ops = &starget_ops;
 621   st->a = getaddr(sc, ADDR_DEST);
 622   dstr_puts(&d, "socket.");
 623   st->a->ops->print(st->a, ADDR_DEST, &d);
 624   st->t.desc = xstrdup(d.buf);
 625   dstr_destroy(&d);
 626   return (&st->t);
 627 }
 628
 629 /* --- @create@ --- *
 630  *
 631  * Arguments:   @target *t@ = pointer to target
 632  *              @const char *desc@ = description of connection
 633  *
 634  * Returns:     Pointer to a created endpoint.
 635  *
 636  * Use:         Generates a target endpoint for communication.
 637  */
 638
 639 static endpt *starget_create(target *t, const char *desc)
 640 {
 641   starget *st = (starget *)t;
 642   stept *e = CREATE(stept);
 643   int fd;
 644   gen_addr *ga = (gen_addr *)st->a;
 645   int opt;
 646
 647   if ((fd = socket(st->a->ops->pf, SOCK_STREAM, 0)) < 0)
 648     return (0);
 649   setsockopt(fd, SOL_SOCKET, SO_OOBINLINE, &opt, sizeof(opt));
 650   fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 651   e->e.ops = &stept_ops;
 652   e->e.other = 0;
 653   e->e.f = EPF_FILE | SKF_CONN;
 654   e->e.t = 0;
 655   e->desc = desc;
 656
 657   /* --- Pay attention --- *
 658    *
 659    * This bit is quite subtle.  The connect can succeed or fail later: that's
 660    * fine.  The problem comes if it makes its mind up right now.  The flag
 661    * @SKF_CONN@ signifies that I'm trying to connect.  I set it up to begin
 662    * with and @stept_go@ turns it off when it's done: @stept_close@ uses it
 663    * to decide whether to kill the connection.  The flag @EPF_PENDING@ is
 664    * only set after @conn_init@ returns and @SKF_CONN@ is still set (meaning
 665    * that the connection is still in progress).  That's used to let
 666    * @stept_go@ know whether to kill the other endpoint.  The flag
 667    * @SKF_BROKEN@ is used to signify an immediate failure.
 668    */
 669
 670   conn_init(&e->c, sel, fd, &ga->sa, ga->a.sz, stept_go, e);
 671   if (e->e.f & SKF_BROKEN) {
 672     DESTROY(e);
 673     return (0);
 674   }
 675   if (e->e.f & SKF_CONN)
 676     e->e.f |= EPF_PENDING;
 677   fw_inc();
 678   return (&e->e);
 679 }
 680
 681 /* --- @destroy@ --- */
 682
 683 static void starget_destroy(target *t)
 684 {
 685   starget *st = (starget *)t;
 686   st->a->ops->destroy(st->a);
 687   /* free(st->t.desc); */
 688   DESTROY(st);
 689 }
 690
 691 /* --- Socket target definition block --- */
 692
 693 target_ops starget_ops = {
 694   "socket",
 695   0, starget_read, starget_create, starget_destroy
 696 };
 697
 698 /*----- That's all, folks -------------------------------------------------*/