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  * $FreeBSD$
  32  */
  33
  34 #include <sys/param.h>
  35 #include <sys/types.h>
  36 #include <sys/socket.h>
  37 #include <sys/ioctl.h>
  38 #include <sys/time.h>
  39 #include <sys/wait.h>
  40
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include <string.h>
  44 #include <syslog.h>
  45 #include <unistd.h>
  46 #include <errno.h>
  47 #include <fcntl.h>
  48 #include <signal.h>
  49
  50 #include <netinet/in.h>
  51 #include <arpa/inet.h>
  52 #include <netdb.h>
  53
  54 #include "faithd.h"
  55
  56 static char tcpbuf[16*1024];
  57         /* bigger than MSS and may be lesser than window size */
  58 static int tblen, tboff, oob_exists;
  59 static fd_set readfds, writefds, exceptfds;
  60 static char atmark_buf[2];
  61 static pid_t cpid = (pid_t)0;
  62 static pid_t ppid = (pid_t)0;
  63 volatile time_t child_lastactive = (time_t)0;
  64 static time_t parent_lastactive = (time_t)0;
  65
  66 static void sig_ctimeout __P((int));
  67 static void sig_child __P((int));
  68 static void notify_inactive __P((void));
  69 static void notify_active __P((void));
  70 static void send_data __P((int, int, const char *, int));
  71 static void relay __P((int, int, const char *, int));
  72
  73 /*
  74  * Inactivity timer:
  75  * - child side (ppid != 0) will send SIGUSR1 to parent every (FAITH_TIMEOUT/4)
  76  *   second if traffic is active.  if traffic is inactive, don't send SIGUSR1.
  77  * - parent side (ppid == 0) will check the last SIGUSR1 it have seen.
  78  */
  79 static void
  80 sig_ctimeout(int sig)
  81 {
  82         /* parent side: record notification from the child */
  83         if (dflag)
  84                 syslog(LOG_DEBUG, "activity timer from child");
  85         child_lastactive = time(NULL);
  86 }
  87
  88 /* parent will terminate if child dies. */
  89 static void
  90 sig_child(int sig)
  91 {
  92         int status;
  93         pid_t pid;
  94
  95         pid = wait3(&status, WNOHANG, (struct rusage *)0);
  96         if (pid > 0 && WEXITSTATUS(status))
  97                 syslog(LOG_WARNING, "child %ld exit status 0x%x",
  98                     (long)pid, status);
  99         exit_success("terminate connection due to child termination");
 100 }
 101
 102 static void
 103 notify_inactive()
 104 {
 105         time_t t;
 106
 107         /* only on parent side... */
 108         if (ppid)
 109                 return;
 110
 111         /* parent side should check for timeout. */
 112         t = time(NULL);
 113         if (dflag) {
 114                 syslog(LOG_DEBUG, "parent side %sactive, child side %sactive",
 115                         (FAITH_TIMEOUT < t - parent_lastactive) ? "in" : "",
 116                         (FAITH_TIMEOUT < t - child_lastactive) ? "in" : "");
 117         }
 118
 119         if (FAITH_TIMEOUT < t - child_lastactive
 120          && FAITH_TIMEOUT < t - parent_lastactive) {
 121                 /* both side timeouted */
 122                 signal(SIGCHLD, SIG_DFL);
 123                 kill(cpid, SIGTERM);
 124                 wait(NULL);
 125                 exit_failure("connection timeout");
 126                 /* NOTREACHED */
 127         }
 128 }
 129
 130 static void
 131 notify_active()
 132 {
 133         if (ppid) {
 134                 /* child side: notify parent of active traffic */
 135                 time_t t;
 136                 t = time(NULL);
 137                 if (FAITH_TIMEOUT / 4 < t - child_lastactive) {
 138                         if (kill(ppid, SIGUSR1) < 0) {
 139                                 exit_failure("terminate connection due to parent termination");
 140                                 /* NOTREACHED */
 141                         }
 142                         child_lastactive = t;
 143                 }
 144         } else {
 145                 /* parent side */
 146                 parent_lastactive = time(NULL);
 147         }
 148 }
 149
 150 static void
 151 send_data(int s_rcv, int s_snd, const char *service, int direction)
 152 {
 153         int cc;
 154
 155         if (oob_exists) {
 156                 cc = send(s_snd, atmark_buf, 1, MSG_OOB);
 157                 if (cc == -1)
 158                         goto retry_or_err;
 159                 oob_exists = 0;
 160                 if (s_rcv >= FD_SETSIZE)
 161                         exit_failure("descriptor too big");
 162                 FD_SET(s_rcv, &exceptfds);
 163         }
 164
 165         for (; tboff < tblen; tboff += cc) {
 166                 cc = write(s_snd, tcpbuf + tboff, tblen - tboff);
 167                 if (cc < 0)
 168                         goto retry_or_err;
 169         }
 170 #ifdef DEBUG
 171         if (tblen) {
 172                 if (tblen >= sizeof(tcpbuf))
 173                         tblen = sizeof(tcpbuf) - 1;
 174                 tcpbuf[tblen] = '\0';
 175                 syslog(LOG_DEBUG, "from %s (%dbytes): %s",
 176                        direction == 1 ? "client" : "server", tblen, tcpbuf);
 177         }
 178 #endif /* DEBUG */
 179         tblen = 0; tboff = 0;
 180         if (s_snd >= FD_SETSIZE)
 181                 exit_failure("descriptor too big");
 182         FD_CLR(s_snd, &writefds);
 183         if (s_rcv >= FD_SETSIZE)
 184                 exit_failure("descriptor too big");
 185         FD_SET(s_rcv, &readfds);
 186         return;
 187     retry_or_err:
 188         if (errno != EAGAIN)
 189                 exit_failure("writing relay data failed: %s", strerror(errno));
 190         if (s_snd >= FD_SETSIZE)
 191                 exit_failure("descriptor too big");
 192         FD_SET(s_snd, &writefds);
 193 }
 194
 195 static void
 196 relay(int s_rcv, int s_snd, const char *service, int direction)
 197 {
 198         int atmark, error, maxfd;
 199         struct timeval tv;
 200         fd_set oreadfds, owritefds, oexceptfds;
 201
 202         FD_ZERO(&readfds);
 203         FD_ZERO(&writefds);
 204         FD_ZERO(&exceptfds);
 205         fcntl(s_snd, F_SETFD, O_NONBLOCK);
 206         oreadfds = readfds; owritefds = writefds; oexceptfds = exceptfds;
 207         if (s_rcv >= FD_SETSIZE)
 208                 exit_failure("descriptor too big");
 209         FD_SET(s_rcv, &readfds);
 210         FD_SET(s_rcv, &exceptfds);
 211         oob_exists = 0;
 212         maxfd = (s_rcv > s_snd) ? s_rcv : s_snd;
 213
 214         for (;;) {
 215                 tv.tv_sec = FAITH_TIMEOUT / 4;
 216                 tv.tv_usec = 0;
 217                 oreadfds = readfds;
 218                 owritefds = writefds;
 219                 oexceptfds = exceptfds;
 220                 error = select(maxfd + 1, &readfds, &writefds, &exceptfds, &tv);
 221                 if (error == -1) {
 222                         if (errno == EINTR)
 223                                 continue;
 224                         exit_failure("select: %s", strerror(errno));
 225                 } else if (error == 0) {
 226                         readfds = oreadfds;
 227                         writefds = owritefds;
 228                         exceptfds = oexceptfds;
 229                         notify_inactive();
 230                         continue;
 231                 }
 232
 233                 /* activity notification */
 234                 notify_active();
 235
 236                 if (FD_ISSET(s_rcv, &exceptfds)) {
 237                         error = ioctl(s_rcv, SIOCATMARK, &atmark);
 238                         if (error != -1 && atmark == 1) {
 239                                 int cc;
 240                             oob_read_retry:
 241                                 cc = read(s_rcv, atmark_buf, 1);
 242                                 if (cc == 1) {
 243                                         if (s_rcv >= FD_SETSIZE)
 244                                                 exit_failure("descriptor too big");
 245                                         FD_CLR(s_rcv, &exceptfds);
 246                                         if (s_snd >= FD_SETSIZE)
 247                                                 exit_failure("descriptor too big");
 248                                         FD_SET(s_snd, &writefds);
 249                                         oob_exists = 1;
 250                                 } else if (cc == -1) {
 251                                         if (errno == EINTR)
 252                                                 goto oob_read_retry;
 253                                         exit_failure("reading oob data failed"
 254                                                      ": %s",
 255                                                      strerror(errno));
 256                                 }
 257                         }
 258                 }
 259                 if (FD_ISSET(s_rcv, &readfds)) {
 260                     relaydata_read_retry:
 261                         tblen = read(s_rcv, tcpbuf, sizeof(tcpbuf));
 262                         tboff = 0;
 263
 264                         switch (tblen) {
 265                         case -1:
 266                                 if (errno == EINTR)
 267                                         goto relaydata_read_retry;
 268                                 exit_failure("reading relay data failed: %s",
 269                                              strerror(errno));
 270                                 /* NOTREACHED */
 271                         case 0:
 272                                 /* to close opposite-direction relay process */
 273                                 shutdown(s_snd, 0);
 274
 275                                 close(s_rcv);
 276                                 close(s_snd);
 277                                 exit_success("terminating %s relay", service);
 278                                 /* NOTREACHED */
 279                         default:
 280                                 if (s_rcv >= FD_SETSIZE)
 281                                         exit_failure("descriptor too big");
 282                                 FD_CLR(s_rcv, &readfds);
 283                                 if (s_snd >= FD_SETSIZE)
 284                                         exit_failure("descriptor too big");
 285                                 FD_SET(s_snd, &writefds);
 286                                 break;
 287                         }
 288                 }
 289                 if (FD_ISSET(s_snd, &writefds))
 290                         send_data(s_rcv, s_snd, service, direction);
 291         }
 292 }
 293
 294 void
 295 tcp_relay(int s_src, int s_dst, const char *service)
 296 {
 297         syslog(LOG_INFO, "starting %s relay", service);
 298
 299         child_lastactive = parent_lastactive = time(NULL);
 300
 301         cpid = fork();
 302         switch (cpid) {
 303         case -1:
 304                 exit_failure("tcp_relay: can't fork grand child: %s",
 305                     strerror(errno));
 306                 /* NOTREACHED */
 307         case 0:
 308                 /* child process: relay going traffic */
 309                 ppid = getppid();
 310                 /* this is child so reopen log */
 311                 closelog();
 312                 openlog(logname, LOG_PID | LOG_NOWAIT, LOG_DAEMON);
 313                 relay(s_src, s_dst, service, 1);
 314                 /* NOTREACHED */
 315         default:
 316                 /* parent process: relay coming traffic */
 317                 ppid = (pid_t)0;
 318                 signal(SIGUSR1, sig_ctimeout);
 319                 signal(SIGCHLD, sig_child);
 320                 relay(s_dst, s_src, service, 0);
 321                 /* NOTREACHED */
 322         }
 323 }