usr.sbin/faithd/tcp.c

   1 /*      $KAME: tcp.c,v 1.13 2003/09/02 22:49:21 itojun Exp $    */
   2
   3 /*
   4  * Copyright (C) 1997 and 1998 WIDE Project.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the project nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 __FBSDID("$FreeBSD$");
  34
  35 #include <sys/param.h>
  36 #include <sys/types.h>
  37 #include <sys/socket.h>
  38 #include <sys/ioctl.h>
  39 #include <sys/time.h>
  40 #include <sys/wait.h>
  41
  42 #include <stdio.h>
  43 #include <stdlib.h>
  44 #include <string.h>
  45 #include <syslog.h>
  46 #include <unistd.h>
  47 #include <errno.h>
  48 #include <fcntl.h>
  49 #include <signal.h>
  50
  51 #include <netinet/in.h>
  52 #include <arpa/inet.h>
  53 #include <netdb.h>
  54
  55 #include "faithd.h"
  56
  57 static char tcpbuf[16*1024];
  58         /* bigger than MSS and may be lesser than window size */
  59 static int tblen, tboff, oob_exists;
  60 static fd_set readfds, writefds, exceptfds;
  61 static char atmark_buf[2];
  62 static pid_t cpid = (pid_t)0;
  63 static pid_t ppid = (pid_t)0;
  64 volatile time_t child_lastactive = (time_t)0;
  65 static time_t parent_lastactive = (time_t)0;
  66
  67 static void sig_ctimeout(int);
  68 static void sig_child(int);
  69 static void notify_inactive(void);
  70 static void notify_active(void);
  71 static void send_data(int, int, const char *, int);
  72 static void relay(int, int, const char *, int);
  73
  74 /*
  75  * Inactivity timer:
  76  * - child side (ppid != 0) will send SIGUSR1 to parent every (FAITH_TIMEOUT/4)
  77  *   second if traffic is active.  if traffic is inactive, don't send SIGUSR1.
  78  * - parent side (ppid == 0) will check the last SIGUSR1 it have seen.
  79  */
  80 static void
  81 sig_ctimeout(int sig __unused)
  82 {
  83         /* parent side: record notification from the child */
  84         if (dflag)
  85                 syslog(LOG_DEBUG, "activity timer from child");
  86         child_lastactive = time(NULL);
  87 }
  88
  89 /* parent will terminate if child dies. */
  90 static void
  91 sig_child(int sig __unused)
  92 {
  93         int status;
  94         pid_t pid;
  95
  96         pid = wait3(&status, WNOHANG, (struct rusage *)0);
  97         if (pid > 0 && WEXITSTATUS(status))
  98                 syslog(LOG_WARNING, "child %ld exit status 0x%x",
  99                     (long)pid, status);
 100         exit_success("terminate connection due to child termination");
 101 }
 102
 103 static void
 104 notify_inactive()
 105 {
 106         time_t t;
 107
 108         /* only on parent side... */
 109         if (ppid)
 110                 return;
 111
 112         /* parent side should check for timeout. */
 113         t = time(NULL);
 114         if (dflag) {
 115                 syslog(LOG_DEBUG, "parent side %sactive, child side %sactive",
 116                         (FAITH_TIMEOUT < t - parent_lastactive) ? "in" : "",
 117                         (FAITH_TIMEOUT < t - child_lastactive) ? "in" : "");
 118         }
 119
 120         if (FAITH_TIMEOUT < t - child_lastactive
 121          && FAITH_TIMEOUT < t - parent_lastactive) {
 122                 /* both side timeouted */
 123                 signal(SIGCHLD, SIG_DFL);
 124                 kill(cpid, SIGTERM);
 125                 wait(NULL);
 126                 exit_failure("connection timeout");
 127                 /* NOTREACHED */
 128         }
 129 }
 130
 131 static void
 132 notify_active()
 133 {
 134         if (ppid) {
 135                 /* child side: notify parent of active traffic */
 136                 time_t t;
 137                 t = time(NULL);
 138                 if (FAITH_TIMEOUT / 4 < t - child_lastactive) {
 139                         if (kill(ppid, SIGUSR1) < 0) {
 140                                 exit_failure("terminate connection due to parent termination");
 141                                 /* NOTREACHED */
 142                         }
 143                         child_lastactive = t;
 144                 }
 145         } else {
 146                 /* parent side */
 147                 parent_lastactive = time(NULL);
 148         }
 149 }
 150
 151 static void
 152 send_data(int s_rcv, int s_snd, const char *service __unused, int direction)
 153 {
 154         int cc;
 155
 156         if (oob_exists) {
 157                 cc = send(s_snd, atmark_buf, 1, MSG_OOB);
 158                 if (cc == -1)
 159                         goto retry_or_err;
 160                 oob_exists = 0;
 161                 if (s_rcv >= FD_SETSIZE)
 162                         exit_failure("descriptor too big");
 163                 FD_SET(s_rcv, &exceptfds);
 164         }
 165
 166         for (; tboff < tblen; tboff += cc) {
 167                 cc = write(s_snd, tcpbuf + tboff, tblen - tboff);
 168                 if (cc < 0)
 169                         goto retry_or_err;
 170         }
 171 #ifdef DEBUG
 172         if (tblen) {
 173                 if (tblen >= sizeof(tcpbuf))
 174                         tblen = sizeof(tcpbuf) - 1;
 175                 tcpbuf[tblen] = '\0';
 176                 syslog(LOG_DEBUG, "from %s (%dbytes): %s",
 177                        direction == 1 ? "client" : "server", tblen, tcpbuf);
 178         }
 179 #endif /* DEBUG */
 180         tblen = 0; tboff = 0;
 181         if (s_snd >= FD_SETSIZE)
 182                 exit_failure("descriptor too big");
 183         FD_CLR(s_snd, &writefds);
 184         if (s_rcv >= FD_SETSIZE)
 185                 exit_failure("descriptor too big");
 186         FD_SET(s_rcv, &readfds);
 187         return;
 188     retry_or_err:
 189         if (errno != EAGAIN)
 190                 exit_failure("writing relay data failed: %s", strerror(errno));
 191         if (s_snd >= FD_SETSIZE)
 192                 exit_failure("descriptor too big");
 193         FD_SET(s_snd, &writefds);
 194 }
 195
 196 static void
 197 relay(int s_rcv, int s_snd, const char *service, int direction)
 198 {
 199         int atmark, error, maxfd;
 200         struct timeval tv;
 201         fd_set oreadfds, owritefds, oexceptfds;
 202
 203         FD_ZERO(&readfds);
 204         FD_ZERO(&writefds);
 205         FD_ZERO(&exceptfds);
 206         fcntl(s_snd, F_SETFD, O_NONBLOCK);
 207         oreadfds = readfds; owritefds = writefds; oexceptfds = exceptfds;
 208         if (s_rcv >= FD_SETSIZE)
 209                 exit_failure("descriptor too big");
 210         FD_SET(s_rcv, &readfds);
 211         FD_SET(s_rcv, &exceptfds);
 212         oob_exists = 0;
 213         maxfd = (s_rcv > s_snd) ? s_rcv : s_snd;
 214
 215         for (;;) {
 216                 tv.tv_sec = FAITH_TIMEOUT / 4;
 217                 tv.tv_usec = 0;
 218                 oreadfds = readfds;
 219                 owritefds = writefds;
 220                 oexceptfds = exceptfds;
 221                 error = select(maxfd + 1, &readfds, &writefds, &exceptfds, &tv);
 222                 if (error == -1) {
 223                         if (errno == EINTR)
 224                                 continue;
 225                         exit_failure("select: %s", strerror(errno));
 226                 } else if (error == 0) {
 227                         readfds = oreadfds;
 228                         writefds = owritefds;
 229                         exceptfds = oexceptfds;
 230                         notify_inactive();
 231                         continue;
 232                 }
 233
 234                 /* activity notification */
 235                 notify_active();
 236
 237                 if (FD_ISSET(s_rcv, &exceptfds)) {
 238                         error = ioctl(s_rcv, SIOCATMARK, &atmark);
 239                         if (error != -1 && atmark == 1) {
 240                                 int cc;
 241                             oob_read_retry:
 242                                 cc = read(s_rcv, atmark_buf, 1);
 243                                 if (cc == 1) {
 244                                         if (s_rcv >= FD_SETSIZE)
 245                                                 exit_failure("descriptor too big");
 246                                         FD_CLR(s_rcv, &exceptfds);
 247                                         if (s_snd >= FD_SETSIZE)
 248                                                 exit_failure("descriptor too big");
 249                                         FD_SET(s_snd, &writefds);
 250                                         oob_exists = 1;
 251                                 } else if (cc == -1) {
 252                                         if (errno == EINTR)
 253                                                 goto oob_read_retry;
 254                                         exit_failure("reading oob data failed"
 255                                                      ": %s",
 256                                                      strerror(errno));
 257                                 }
 258                         }
 259                 }
 260                 if (FD_ISSET(s_rcv, &readfds)) {
 261                     relaydata_read_retry:
 262                         tblen = read(s_rcv, tcpbuf, sizeof(tcpbuf));
 263                         tboff = 0;
 264
 265                         switch (tblen) {
 266                         case -1:
 267                                 if (errno == EINTR)
 268                                         goto relaydata_read_retry;
 269                                 exit_failure("reading relay data failed: %s",
 270                                              strerror(errno));
 271                                 /* NOTREACHED */
 272                         case 0:
 273                                 /* to close opposite-direction relay process */
 274                                 shutdown(s_snd, 0);
 275
 276                                 close(s_rcv);
 277                                 close(s_snd);
 278                                 exit_success("terminating %s relay", service);
 279                                 /* NOTREACHED */
 280                         default:
 281                                 if (s_rcv >= FD_SETSIZE)
 282                                         exit_failure("descriptor too big");
 283                                 FD_CLR(s_rcv, &readfds);
 284                                 if (s_snd >= FD_SETSIZE)
 285                                         exit_failure("descriptor too big");
 286                                 FD_SET(s_snd, &writefds);
 287                                 break;
 288                         }
 289                 }
 290                 if (FD_ISSET(s_snd, &writefds))
 291                         send_data(s_rcv, s_snd, service, direction);
 292         }
 293 }
 294
 295 void
 296 tcp_relay(int s_src, int s_dst, const char *service)
 297 {
 298         syslog(LOG_INFO, "starting %s relay", service);
 299
 300         child_lastactive = parent_lastactive = time(NULL);
 301
 302         cpid = fork();
 303         switch (cpid) {
 304         case -1:
 305                 exit_failure("tcp_relay: can't fork grand child: %s",
 306                     strerror(errno));
 307                 /* NOTREACHED */
 308         case 0:
 309                 /* child process: relay going traffic */
 310                 ppid = getppid();
 311                 /* this is child so reopen log */
 312                 closelog();
 313                 openlog(logname, LOG_PID | LOG_NOWAIT, LOG_DAEMON);
 314                 relay(s_src, s_dst, service, 1);
 315                 /* NOTREACHED */
 316         default:
 317                 /* parent process: relay coming traffic */
 318                 ppid = (pid_t)0;
 319                 signal(SIGUSR1, sig_ctimeout);
 320                 signal(SIGCHLD, sig_child);
 321                 relay(s_dst, s_src, service, 0);
 322                 /* NOTREACHED */
 323         }
 324 }