mdw@git.distorted.org.uk Git - tripe/blob - peer.c

   1 /* -*-c-*-
   2  *
   3  * $Id$
   4  *
   5  * Communication with the peer
   6  *
   7  * (c) 2001 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Trivial IP Encryption (TrIPE).
  13  *
  14  * TrIPE 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  * TrIPE 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 TrIPE; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Header files ------------------------------------------------------*/
  30
  31 #include "tripe.h"
  32
  33 /*----- Static variables --------------------------------------------------*/
  34
  35 static peer *peers = 0;
  36 static sel_file sock;
  37
  38 /*----- Tunnel table ------------------------------------------------------*/
  39
  40 const tunnel_ops *tunnels[] = {
  41 #ifdef TUN_LINUX
  42   &tun_linux,
  43 #endif
  44 #ifdef TUN_BSD
  45   &tun_bsd,
  46 #endif
  47 #ifdef TUN_UNET
  48   &tun_unet,
  49 #endif
  50   &tun_slip,
  51   0
  52 }, *tun_default;
  53
  54 /*----- Main code ---------------------------------------------------------*/
  55
  56 /* --- @p_pingtype@ --- *
  57  *
  58  * Arguments:   @unsigned msg@ = message type
  59  *
  60  * Returns:     String to describe the message.
  61  */
  62
  63 static const char *p_pingtype(unsigned msg)
  64 {
  65   switch (msg & MSG_TYPEMASK) {
  66     case MISC_PING:
  67     case MISC_PONG:
  68       return "transport-ping";
  69     case MISC_EPING:
  70     case MISC_EPONG:
  71       return "encrypted-ping";
  72     default:
  73       abort();
  74   }
  75 }
  76
  77 /* --- @p_ponged@ --- *
  78  *
  79  * Arguments:   @peer *p@ = peer packet arrived from
  80  *              @unsigned msg@ = message type
  81  *              @buf *b@ = buffer containing payload
  82  *
  83  * Returns:     ---
  84  *
  85  * Use:         Processes a ping response.
  86  */
  87
  88 static void p_ponged(peer *p, unsigned msg, buf *b)
  89 {
  90   uint32 id;
  91   const octet *magic;
  92   ping *pg;
  93
  94   IF_TRACING(T_PEER, {
  95     trace(T_PEER, "peer: received %s reply from %s",
  96           p_pingtype(msg), p->spec.name);
  97     trace_block(T_PACKET, "peer: ping contents", BBASE(b), BSZ(b));
  98   })
  99
 100   if (buf_getu32(b, &id) ||
 101       (magic = buf_get(b, sizeof(pg->magic))) == 0 ||
 102       BLEFT(b)) {
 103     a_warn("PEER %s malformed-%s", p->spec.name, p_pingtype(msg));
 104     return;
 105   }
 106
 107   for (pg = p->pings; pg; pg = pg->next) {
 108     if (pg->id == id)
 109       goto found;
 110   }
 111   a_warn("PEER %s unexpected-%s 0x%08lx",
 112          p->spec.name, p_pingtype(msg), (unsigned long)id);
 113   return;
 114
 115 found:
 116   if (memcmp(magic, pg->magic, sizeof(pg->magic)) != 0) {
 117     a_warn("PEER %s corrupt-%s", p->spec.name, p_pingtype(msg));
 118     return;
 119   }
 120   p_pingdone(pg, PING_OK);
 121 }
 122
 123 /* --- @p_read@ --- *
 124  *
 125  * Arguments:   @int fd@ = file descriptor to read from
 126  *              @unsigned mode@ = what happened
 127  *              @void *v@ = an uninteresting pointer
 128  *
 129  * Returns:     ---
 130  *
 131  * Use:         Reads a packet from somewhere.
 132  */
 133
 134 static void p_read(int fd, unsigned mode, void *v)
 135 {
 136   peer *p;
 137   addr a;
 138   size_t sz;
 139   ssize_t n;
 140   int ch;
 141   buf b, bb;
 142
 143   /* --- Read the data --- */
 144
 145   TIMER;
 146   sz = sizeof(addr);
 147   n = recvfrom(fd, buf_i, sizeof(buf_i), 0, &a.sa, &sz);
 148   if (n < 0) {
 149     a_warn("PEER - socket-read-error -- %s", strerror(errno));
 150     return;
 151   }
 152
 153   /* --- Find the appropriate peer --- */
 154
 155   assert(a.sa.sa_family == AF_INET);
 156   for (p = peers; p; p = p->next) {
 157     if (p->spec.sa.sin.sin_addr.s_addr == a.sin.sin_addr.s_addr &&
 158         p->spec.sa.sin.sin_port == a.sin.sin_port)
 159       goto found;
 160   }
 161   a_warn("PEER - unexpected-source INET %s %u",
 162          inet_ntoa(a.sin.sin_addr), (unsigned)ntohs(a.sin.sin_port));
 163   return;
 164
 165 found:
 166   IF_TRACING(T_PEER, {
 167     trace(T_PEER, "peer: packet received from `%s'", p->spec.name);
 168     trace_block(T_PACKET, "peer: packet contents", buf_i, n);
 169   })
 170
 171   /* --- Pick the packet apart --- */
 172
 173   p->st.t_last = time(0);
 174   p->st.n_in++;
 175   p->st.sz_in += n;
 176   buf_init(&b, buf_i, n);
 177   if ((ch = buf_getbyte(&b)) < 0) {
 178     a_warn("PEER %s bad-packet no-type", p->spec.name);
 179     return;
 180   }
 181   switch (ch & MSG_CATMASK) {
 182     case MSG_PACKET:
 183       if (ch & MSG_TYPEMASK) {
 184         a_warn("PEER %s bad-packet unknown-type 0x%02x", p->spec.name, ch);
 185         p->st.n_reject++;
 186         return;
 187       }
 188       buf_init(&bb, buf_o, sizeof(buf_o));
 189       if (ksl_decrypt(&p->ks, MSG_PACKET, &b, &bb)) {
 190         p->st.n_reject++;
 191         a_warn("PEER %s decrypt-failed", p->spec.name);
 192         return;
 193       }
 194       if (BOK(&bb)) {
 195         p->st.n_ipin++;
 196         p->st.sz_ipin += BSZ(&b);
 197         p->t->ops->inject(p->t, &bb);
 198       } else {
 199         p->st.n_reject++;
 200         a_warn("PEER %s packet-build-failed", p->spec.name);
 201       }
 202       break;
 203     case MSG_KEYEXCH:
 204       kx_message(&p->kx, ch & MSG_TYPEMASK, &b);
 205       break;
 206     case MSG_MISC:
 207       switch (ch & MSG_TYPEMASK) {
 208         case MISC_NOP:
 209           T( trace(T_PEER, "peer: received NOP packet"); )
 210           break;
 211         case MISC_PING:
 212           buf_put(p_txstart(p, MSG_MISC | MISC_PONG), BCUR(&b), BLEFT(&b));
 213           p_txend(p);
 214           break;
 215         case MISC_PONG:
 216           p_ponged(p, MISC_PONG, &b);
 217           break;
 218         case MISC_EPING:
 219           buf_init(&bb, buf_t, sizeof(buf_t));
 220           if (ksl_decrypt(&p->ks, ch, &b, &bb)) {
 221             p->st.n_reject++;
 222             a_warn("PEER %s decrypt-failed", p->spec.name);
 223             return;
 224           }
 225           if (BOK(&bb)) {
 226             buf_flip(&bb);
 227             if (ksl_encrypt(&p->ks, MSG_MISC | MISC_EPONG, &bb,
 228                             p_txstart(p, MSG_MISC | MISC_EPONG)))
 229               kx_start(&p->kx);
 230             p_txend(p);
 231           }
 232           break;
 233         case MISC_EPONG:
 234           buf_init(&bb, buf_t, sizeof(buf_t));
 235           if (ksl_decrypt(&p->ks, ch, &b, &bb)) {
 236             p->st.n_reject++;
 237             a_warn("PEER %s decrypt-failed", p->spec.name);
 238             return;
 239           }
 240           if (BOK(&bb)) {
 241             buf_flip(&bb);
 242             p_ponged(p, MISC_EPONG, &bb);
 243           }
 244           break;
 245       }
 246       break;
 247     default:
 248       p->st.n_reject++;
 249       a_warn("PEER %s bad-packet unknown-category 0x%02x", p->spec.name, ch);
 250       break;
 251   }
 252 }
 253
 254 /* --- @p_txstart@ --- *
 255  *
 256  * Arguments:   @peer *p@ = pointer to peer block
 257  *              @unsigned msg@ = message type code
 258  *
 259  * Returns:     A pointer to a buffer to write to.
 260  *
 261  * Use:         Starts sending to a peer.  Only one send can happen at a
 262  *              time.
 263  */
 264
 265 buf *p_txstart(peer *p, unsigned msg)
 266 {
 267   buf_init(&p->b, buf_o, sizeof(buf_o));
 268   buf_putbyte(&p->b, msg);
 269   return (&p->b);
 270 }
 271
 272 /* --- @p_txend@ --- *
 273  *
 274  * Arguments:   @peer *p@ = pointer to peer block
 275  *
 276  * Returns:     ---
 277  *
 278  * Use:         Sends a packet to the peer.
 279  */
 280
 281 static void p_setkatimer(peer *);
 282
 283 static int p_dotxend(peer *p)
 284 {
 285   if (!BOK(&p->b)) {
 286     a_warn("PEER %s packet-build-failed", p->spec.name);
 287     return (0);
 288   }
 289   IF_TRACING(T_PEER, trace_block(T_PACKET, "peer: sending packet",
 290                                  BBASE(&p->b), BLEN(&p->b)); )
 291   if (sendto(sock.fd, BBASE(&p->b), BLEN(&p->b),
 292              0, &p->spec.sa.sa, p->spec.sasz) < 0) {
 293     a_warn("PEER %s socket-write-error -- %s",
 294            p->spec.name, strerror(errno));
 295     return (0);
 296   } else {
 297     p->st.n_out++;
 298     p->st.sz_out += BLEN(&p->b);
 299     return (1);
 300   }
 301 }
 302
 303 void p_txend(peer *p)
 304 {
 305   if (p_dotxend(p) && p->spec.t_ka) {
 306     sel_rmtimer(&p->tka);
 307     p_setkatimer(p);
 308   }
 309 }
 310
 311 /* --- @p_pingwrite@ --- *
 312  *
 313  * Arguments:   @ping *p@ = ping structure
 314  *              @buf *b@ = buffer to write in
 315  *
 316  * Returns:     ---
 317  *
 318  * Use:         Fills in a ping structure and writes the packet payload.
 319  */
 320
 321 static void p_pingwrite(ping *p, buf *b)
 322 {
 323   static uint32 seq = 0;
 324
 325   p->id = U32(seq++);
 326   GR_FILL(&rand_global, p->magic, sizeof(p->magic));
 327   buf_putu32(b, p->id);
 328   buf_put(b, p->magic, sizeof(p->magic));
 329 }
 330
 331 /* --- @p_pingdone@ --- *
 332  *
 333  * Arguments:   @ping *p@ = ping structure
 334  *              @int rc@ = return code to pass on
 335  *
 336  * Returns:     ---
 337  *
 338  * Use:         Disposes of a ping structure, maybe sending a notification.
 339  */
 340
 341 void p_pingdone(ping *p, int rc)
 342 {
 343   if (!p->p) return;
 344   if (p->prev) p->prev->next = p->next;
 345   else p->p->pings = p->next;
 346   if (p->next) p->next->prev = p->prev;
 347   if (rc != PING_TIMEOUT) sel_rmtimer(&p->t);
 348   p->p = 0;
 349   if (rc >= 0) p->func(rc, p->arg);
 350 }
 351
 352 /* --- @p_pingtimeout@ --- *
 353  *
 354  * Arguments:   @struct timeval *now@ = the time now
 355  *              @void *pv@ = pointer to ping block
 356  *
 357  * Returns:     ---
 358  *
 359  * Use:         Called when a ping times out.
 360  */
 361
 362 static void p_pingtimeout(struct timeval *now, void *pv)
 363 {
 364   ping *p = pv;
 365
 366   T( trace(T_PEER, "peer: ping 0x%08lx timed out", (unsigned long)p->id); )
 367   p_pingdone(p, PING_TIMEOUT);
 368 }
 369
 370 /* --- @p_pingsend@ --- *
 371  *
 372  * Arguments:   @peer *p@ = destination peer
 373  *              @ping *pg@ = structure to fill in
 374  *              @unsigned type@ = message type
 375  *              @unsigned long timeout@ = how long to wait before giving up
 376  *              @void (*func)(int, void *)@ = callback function
 377  *              @void *arg@ = argument for callback
 378  *
 379  * Returns:     Zero if successful, nonzero if it failed.
 380  *
 381  * Use:         Sends a ping to a peer.  Call @func@ with a nonzero argument
 382  *              if we get an answer within the timeout, or zero if no answer.
 383  */
 384
 385 int p_pingsend(peer *p, ping *pg, unsigned type,
 386                unsigned long timeout,
 387                void (*func)(int, void *), void *arg)
 388 {
 389   buf *b, bb;
 390   struct timeval tv;
 391
 392   assert(!pg->p);
 393
 394   switch (type) {
 395     case MISC_PING:
 396       pg->msg = MISC_PONG;
 397       b = p_txstart(p, MSG_MISC | MISC_PING);
 398       p_pingwrite(pg, b);
 399       p_txend(p);
 400       break;
 401     case MISC_EPING:
 402       pg->msg = MISC_EPONG;
 403       b = p_txstart(p, MSG_MISC | MISC_EPING);
 404       buf_init(&bb, buf_t, sizeof(buf_t));
 405       p_pingwrite(pg, &bb);
 406       buf_flip(&bb);
 407       if (ksl_encrypt(&p->ks, MSG_MISC | MISC_EPING, &bb, b))
 408         kx_start(&p->kx);
 409       if (!BOK(b))
 410         return (-1);
 411       p_txend(p);
 412       break;
 413     default:
 414       abort();
 415       break;
 416   }
 417
 418   pg->next = p->pings;
 419   pg->prev = 0;
 420   pg->p = p;
 421   pg->func = func;
 422   pg->arg = arg;
 423   p->pings = pg;
 424   gettimeofday(&tv, 0);
 425   tv.tv_sec += timeout;
 426   sel_addtimer(&sel, &pg->t, &tv, p_pingtimeout, pg);
 427   T( trace(T_PEER, "peer: send %s 0x%08lx to %s",
 428            p_pingtype(type), (unsigned long)pg->id, p->spec.name); )
 429   return (0);
 430 }
 431
 432 /* --- @p_tun@ --- *
 433  *
 434  * Arguments:   @peer *p@ = pointer to peer block
 435  *              @buf *b@ = buffer containing incoming packet
 436  *
 437  * Returns:     ---
 438  *
 439  * Use:         Handles a packet which needs to be sent to a peer.
 440  */
 441
 442 void p_tun(peer *p, buf *b)
 443 {
 444   buf *bb = p_txstart(p, MSG_PACKET);
 445
 446   TIMER;
 447   if (ksl_encrypt(&p->ks, MSG_PACKET, b, bb))
 448     kx_start(&p->kx);
 449   if (BOK(bb) && BLEN(bb)) {
 450     p->st.n_ipout++;
 451     p->st.sz_ipout += BLEN(bb);
 452     p_txend(p);
 453   }
 454 }
 455
 456 /* --- @p_interval@ --- *
 457  *
 458  * Arguments:   ---
 459  *
 460  * Returns:     ---
 461  *
 462  * Use:         Called periodically to do tidying.
 463  */
 464
 465 void p_interval(void)
 466 {
 467   peer *p, *pp;
 468   int reload;
 469
 470   reload = km_interval();
 471   for (p = peers; p; p = pp) {
 472     pp = p->next;
 473     if (reload)
 474       kx_newkeys(&p->kx);
 475     ksl_prune(&p->ks);
 476   }
 477 }
 478
 479 /* --- @p_stats@ --- *
 480  *
 481  * Arguments:   @peer *p@ = pointer to a peer block
 482  *
 483  * Returns:     A pointer to the peer's statistics.
 484  */
 485
 486 stats *p_stats(peer *p) { return (&p->st); }
 487
 488 /* --- @p_ifname@ --- *
 489  *
 490  * Arguments:   @peer *p@ = pointer to a peer block
 491  *
 492  * Returns:     A pointer to the peer's interface name.
 493  */
 494
 495 const char *p_ifname(peer *p) { return (p->t->ops->ifname(p->t)); }
 496
 497 /* --- @p_addr@ --- *
 498  *
 499  * Arguments:   @peer *p@ = pointer to a peer block
 500  *
 501  * Returns:     A pointer to the peer's address.
 502  */
 503
 504 const addr *p_addr(peer *p) { return (&p->spec.sa); }
 505
 506 /* --- @p_init@ --- *
 507  *
 508  * Arguments:   @struct in_addr addr@ = address to bind to
 509  *              @unsigned port@ = port number to listen to
 510  *
 511  * Returns:     ---
 512  *
 513  * Use:         Initializes the peer system; creates the socket.
 514  */
 515
 516 void p_init(struct in_addr addr, unsigned port)
 517 {
 518   int fd;
 519   struct sockaddr_in sin;
 520   int len = PKBUFSZ;
 521
 522   /* --- Note on socket buffer sizes --- *
 523    *
 524    * For some bizarre reason, Linux 2.2 (at least) doubles the socket buffer
 525    * sizes I pass to @setsockopt@.  I'm not putting special-case code here
 526    * for Linux: BSD (at least TCPv2) does what I tell it rather than second-
 527    * guessing me.
 528    */
 529
 530   if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0)
 531     die(EXIT_FAILURE, "socket creation failed: %s", strerror(errno));
 532   BURN(sin);
 533   sin.sin_family = AF_INET;
 534   sin.sin_addr = addr;
 535   sin.sin_port = htons(port);
 536   if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)))
 537     die(EXIT_FAILURE, "bind failed: %s", strerror(errno));
 538   if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &len, sizeof(len)) ||
 539       setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &len, sizeof(len))) {
 540     die(EXIT_FAILURE, "failed to set socket buffer sizes: %s",
 541         strerror(errno));
 542   }
 543   fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 544   sel_initfile(&sel, &sock, fd, SEL_READ, p_read, 0);
 545   sel_addfile(&sock);
 546   T( trace(T_PEER, "peer: created socket"); )
 547 }
 548
 549 /* --- @p_port@ --- *
 550  *
 551  * Arguments:   ---
 552  *
 553  * Returns:     Port number used for socket.
 554  */
 555
 556 unsigned p_port(void)
 557 {
 558   addr a;
 559   size_t sz = sizeof(addr);
 560
 561   if (getsockname(sock.fd, &a.sa, &sz))
 562     die(EXIT_FAILURE, "couldn't read port number: %s", strerror(errno));
 563   assert(a.sa.sa_family == AF_INET);
 564   return (ntohs(a.sin.sin_port));
 565 }
 566
 567 /* --- @p_keepalive@ --- *
 568  *
 569  * Arguments:   @struct timeval *now@ = the current time
 570  *              @void *pv@ = peer to wake up
 571  *
 572  * Returns:     ---
 573  *
 574  * Use:         Sends a keepalive ping message to its peer.
 575  */
 576
 577 static void p_keepalive(struct timeval *now, void *pv)
 578 {
 579   peer *p = pv;
 580   p_txstart(p, MSG_MISC | MISC_NOP); p_dotxend(p);
 581   T( trace(T_PEER, "peer: sent keepalive to %s", p->spec.name); )
 582   p_setkatimer(p);
 583 }
 584
 585 /* --- @p_setkatimer@ --- *
 586  *
 587  * Arguments:   @peer *p@ = peer to set
 588  *
 589  * Returns:     ---
 590  *
 591  * Use:         Resets the keepalive timer thing.
 592  */
 593
 594 static void p_setkatimer(peer *p)
 595 {
 596   struct timeval tv;
 597
 598   if (!p->spec.t_ka)
 599     return;
 600   gettimeofday(&tv, 0);
 601   tv.tv_sec += p->spec.t_ka;
 602   sel_addtimer(&sel, &p->tka, &tv, p_keepalive, p);
 603 }
 604
 605 /* --- @p_create@ --- *
 606  *
 607  * Arguments:   @peerspec *spec@ = information about this peer
 608  *
 609  * Returns:     Pointer to the peer block, or null if it failed.
 610  *
 611  * Use:         Creates a new named peer block.  No peer is actually attached
 612  *              by this point.
 613  */
 614
 615 peer *p_create(peerspec *spec)
 616 {
 617   peer *p = CREATE(peer);
 618
 619   T( trace(T_PEER, "peer: creating new peer `%s'", spec->name); )
 620   p->spec = *spec;
 621   p->spec.name = xstrdup(spec->name);
 622   p->ks = 0;
 623   p->prev = 0;
 624   p->pings = 0;
 625   memset(&p->st, 0, sizeof(stats));
 626   p->st.t_start = time(0);
 627   if ((p->t = spec->tops->create(p)) == 0)
 628     goto tidy_0;
 629   p_setkatimer(p);
 630   if (kx_init(&p->kx, p, &p->ks))
 631     goto tidy_1;
 632   p->next = peers;
 633   if (peers)
 634     peers->prev = p;
 635   peers = p;
 636   switch (p->spec.sa.sa.sa_family) {
 637     case AF_INET:
 638       a_notify("ADD %s %s INET %s %u",
 639                spec->name,
 640                p->t->ops->ifname(p->t),
 641                inet_ntoa(p->spec.sa.sin.sin_addr),
 642                (unsigned)ntohs(p->spec.sa.sin.sin_port));
 643       break;
 644     default:
 645       a_notify("ADD %s %s UNKNOWN", spec->name, p->t->ops->ifname(p->t));
 646       break;
 647   }
 648   a_notify("KXSTART %s", spec->name);   /* Couldn't tell anyone before */
 649   return (p);
 650
 651 tidy_1:
 652   if (spec->t_ka)
 653     sel_rmtimer(&p->tka);
 654   p->t->ops->destroy(p->t);
 655 tidy_0:
 656   xfree(p->spec.name);
 657   DESTROY(p);
 658   return (0);
 659 }
 660
 661 /* --- @p_name@ --- *
 662  *
 663  * Arguments:   @peer *p@ = pointer to a peer block
 664  *
 665  * Returns:     A pointer to the peer's name.
 666  */
 667
 668 const char *p_name(peer *p) { return (p->spec.name); }
 669
 670 /* --- @p_find@ --- *
 671  *
 672  * Arguments:   @const char *name@ = name to look up
 673  *
 674  * Returns:     Pointer to the peer block, or null if not found.
 675  *
 676  * Use:         Finds a peer by name.
 677  */
 678
 679 peer *p_find(const char *name)
 680 {
 681   peer *p;
 682   for (p = peers; p; p = p->next) {
 683     if (strcmp(name, p->spec.name) == 0)
 684       return (p);
 685   }
 686   return (0);
 687 }
 688
 689 /* --- @p_destroy@ --- *
 690  *
 691  * Arguments:   @peer *p@ = pointer to a peer
 692  *
 693  * Returns:     ---
 694  *
 695  * Use:         Destroys a peer.
 696  */
 697
 698 void p_destroy(peer *p)
 699 {
 700   ping *pg, *ppg;
 701
 702   T( trace(T_PEER, "peer: destroying peer `%s'", p->spec.name); )
 703   a_notify("KILL %s", p->spec.name);
 704   ksl_free(&p->ks);
 705   kx_free(&p->kx);
 706   p->t->ops->destroy(p->t);
 707   if (p->spec.t_ka)
 708     sel_rmtimer(&p->tka);
 709   xfree(p->spec.name);
 710   for (pg = p->pings; pg; pg = ppg) {
 711     ppg = pg->next;
 712     p_pingdone(pg, PING_PEERDIED);
 713   }
 714   if (p->next)
 715     p->next->prev = p->prev;
 716   if (p->prev)
 717     p->prev->next = p->next;
 718   else
 719     peers = p->next;
 720   DESTROY(p);
 721 }
 722
 723 /* --- @p_first@, @p_next@ --- *
 724  *
 725  * Arguments:   @peer *p@ = a peer block
 726  *
 727  * Returns:     @peer_first@ returns the first peer in some ordering;
 728  *              @peer_next@ returns the peer following a given one in the
 729  *              same ordering.  Null is returned for the end of the list.
 730  */
 731
 732 peer *p_first(void) { return (peers); }
 733 peer *p_next(peer *p) { return (p->next); }
 734
 735 /*----- That's all, folks -------------------------------------------------*/