usr.sbin/faithd/tcp.c

   1 /*      $KAME: tcp.c,v 1.8 2001/11/21 07:40:22 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: src/usr.sbin/faithd/tcp.c,v 1.1.2.3 2002/04/28 05:40:29 suz Exp $
  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 && WEXITSTATUS(status))
  97                 syslog(LOG_WARNING, "child %d exit status 0x%x", pid, status);
  98         exit_success("terminate connection due to child termination");
  99 }
 100
 101 static void
 102 notify_inactive()
 103 {
 104         time_t t;
 105
 106         /* only on parent side... */
 107         if (ppid)
 108                 return;
 109
 110         /* parent side should check for timeout. */
 111         t = time(NULL);
 112         if (dflag) {
 113                 syslog(LOG_DEBUG, "parent side %sactive, child side %sactive",
 114                         (FAITH_TIMEOUT < t - parent_lastactive) ? "in" : "",
 115                         (FAITH_TIMEOUT < t - child_lastactive) ? "in" : "");
 116         }
 117
 118         if (FAITH_TIMEOUT < t - child_lastactive
 119          && FAITH_TIMEOUT < t - parent_lastactive) {
 120                 /* both side timeouted */
 121                 signal(SIGCHLD, SIG_DFL);
 122                 kill(cpid, SIGTERM);
 123                 wait(NULL);
 124                 exit_failure("connection timeout");
 125                 /* NOTREACHED */
 126         }
 127 }
 128
 129 static void
 130 notify_active()
 131 {
 132         if (ppid) {
 133                 /* child side: notify parent of active traffic */
 134                 time_t t;
 135                 t = time(NULL);
 136                 if (FAITH_TIMEOUT / 4 < t - child_lastactive) {
 137                         if (kill(ppid, SIGUSR1) < 0) {
 138                                 exit_failure("terminate connection due to parent termination");
 139                                 /* NOTREACHED */
 140                         }
 141                         child_lastactive = t;
 142                 }
 143         } else {
 144                 /* parent side */
 145                 parent_lastactive = time(NULL);
 146         }
 147 }
 148
 149 static void
 150 send_data(int s_rcv, int s_snd, const char *service, int direction)
 151 {
 152         int cc;
 153
 154         if (oob_exists) {
 155                 cc = send(s_snd, atmark_buf, 1, MSG_OOB);
 156                 if (cc == -1)
 157                         goto retry_or_err;
 158                 oob_exists = 0;
 159                 FD_SET(s_rcv, &exceptfds);
 160         }
 161
 162         for (; tboff < tblen; tboff += cc) {
 163                 cc = write(s_snd, tcpbuf + tboff, tblen - tboff);
 164                 if (cc < 0)
 165                         goto retry_or_err;
 166         }
 167 #ifdef DEBUG
 168         if (tblen) {
 169                 if (tblen >= sizeof(tcpbuf))
 170                         tblen = sizeof(tcpbuf) - 1;
 171                 tcpbuf[tblen] = '\0';
 172                 syslog(LOG_DEBUG, "from %s (%dbytes): %s",
 173                        direction == 1 ? "client" : "server", tblen, tcpbuf);
 174         }
 175 #endif /* DEBUG */
 176         tblen = 0; tboff = 0;
 177         FD_CLR(s_snd, &writefds);
 178         FD_SET(s_rcv, &readfds);
 179         return;
 180     retry_or_err:
 181         if (errno != EAGAIN)
 182                 exit_failure("writing relay data failed: %s", strerror(errno));
 183         FD_SET(s_snd, &writefds);
 184 }
 185
 186 static void
 187 relay(int s_rcv, int s_snd, const char *service, int direction)
 188 {
 189         int atmark, error, maxfd;
 190         struct timeval tv;
 191         fd_set oreadfds, owritefds, oexceptfds;
 192
 193         FD_ZERO(&readfds);
 194         FD_ZERO(&writefds);
 195         FD_ZERO(&exceptfds);
 196         fcntl(s_snd, F_SETFD, O_NONBLOCK);
 197         oreadfds = readfds; owritefds = writefds; oexceptfds = exceptfds;
 198         FD_SET(s_rcv, &readfds);
 199         FD_SET(s_rcv, &exceptfds);
 200         oob_exists = 0;
 201         maxfd = (s_rcv > s_snd) ? s_rcv : s_snd;
 202
 203         for (;;) {
 204                 tv.tv_sec = FAITH_TIMEOUT / 4;
 205                 tv.tv_usec = 0;
 206                 oreadfds = readfds;
 207                 owritefds = writefds;
 208                 oexceptfds = exceptfds;
 209                 error = select(maxfd + 1, &readfds, &writefds, &exceptfds, &tv);
 210                 if (error == -1) {
 211                         if (errno == EINTR)
 212                                 continue;
 213                         exit_failure("select: %s", strerror(errno));
 214                 } else if (error == 0) {
 215                         readfds = oreadfds;
 216                         writefds = owritefds;
 217                         exceptfds = oexceptfds;
 218                         notify_inactive();
 219                         continue;
 220                 }
 221
 222                 /* activity notification */
 223                 notify_active();
 224
 225                 if (FD_ISSET(s_rcv, &exceptfds)) {
 226                         error = ioctl(s_rcv, SIOCATMARK, &atmark);
 227                         if (error != -1 && atmark == 1) {
 228                                 int cc;
 229                             oob_read_retry:
 230                                 cc = read(s_rcv, atmark_buf, 1);
 231                                 if (cc == 1) {
 232                                         FD_CLR(s_rcv, &exceptfds);
 233                                         FD_SET(s_snd, &writefds);
 234                                         oob_exists = 1;
 235                                 } else if (cc == -1) {
 236                                         if (errno == EINTR)
 237                                                 goto oob_read_retry;
 238                                         exit_failure("reading oob data failed"
 239                                                      ": %s",
 240                                                      strerror(errno));
 241                                 }
 242                         }
 243                 }
 244                 if (FD_ISSET(s_rcv, &readfds)) {
 245                     relaydata_read_retry:
 246                         tblen = read(s_rcv, tcpbuf, sizeof(tcpbuf));
 247                         tboff = 0;
 248
 249                         switch (tblen) {
 250                         case -1:
 251                                 if (errno == EINTR)
 252                                         goto relaydata_read_retry;
 253                                 exit_failure("reading relay data failed: %s",
 254                                              strerror(errno));
 255                                 /* NOTREACHED */
 256                         case 0:
 257                                 /* to close opposite-direction relay process */
 258                                 shutdown(s_snd, 0);
 259
 260                                 close(s_rcv);
 261                                 close(s_snd);
 262                                 exit_success("terminating %s relay", service);
 263                                 /* NOTREACHED */
 264                         default:
 265                                 FD_CLR(s_rcv, &readfds);
 266                                 FD_SET(s_snd, &writefds);
 267                                 break;
 268                         }
 269                 }
 270                 if (FD_ISSET(s_snd, &writefds))
 271                         send_data(s_rcv, s_snd, service, direction);
 272         }
 273 }
 274
 275 void
 276 tcp_relay(int s_src, int s_dst, const char *service)
 277 {
 278         syslog(LOG_INFO, "starting %s relay", service);
 279
 280         child_lastactive = parent_lastactive = time(NULL);
 281
 282         cpid = fork();
 283         switch (cpid) {
 284         case -1:
 285                 exit_failure("tcp_relay: can't fork grand child: %s",
 286                     strerror(errno));
 287                 /* NOTREACHED */
 288         case 0:
 289                 /* child process: relay going traffic */
 290                 ppid = getppid();
 291                 /* this is child so reopen log */
 292                 closelog();
 293                 openlog(logname, LOG_PID | LOG_NOWAIT, LOG_DAEMON);
 294                 relay(s_src, s_dst, service, 1);
 295                 /* NOTREACHED */
 296         default:
 297                 /* parent process: relay coming traffic */
 298                 ppid = (pid_t)0;
 299                 signal(SIGUSR1, sig_ctimeout);
 300                 signal(SIGCHLD, sig_child);
 301                 relay(s_dst, s_src, service, 0);
 302                 /* NOTREACHED */
 303         }
 304 }