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  * $DragonFly: src/usr.sbin/faithd/tcp.c,v 1.5 2007/05/18 17:05:12 dillon Exp $
  33  */
  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)
  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)
  92 {
  93         int status;
  94         pid_t pid;
  95
  96         pid = wait3(&status, WNOHANG, (struct rusage *)0);
  97         if (pid && WEXITSTATUS(status))
  98                 syslog(LOG_WARNING, "child %d exit status 0x%x", pid, status);
  99         exit_success("terminate connection due to child termination");
 100 }
 101
 102 static void
 103 notify_inactive(void)
 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(void)
 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                 FD_SET(s_rcv, &exceptfds);
 161         }
 162
 163         for (; tboff < tblen; tboff += cc) {
 164                 cc = write(s_snd, tcpbuf + tboff, tblen - tboff);
 165                 if (cc < 0)
 166                         goto retry_or_err;
 167         }
 168 #ifdef DEBUG
 169         if (tblen) {
 170                 if (tblen >= sizeof(tcpbuf))
 171                         tblen = sizeof(tcpbuf) - 1;
 172                 tcpbuf[tblen] = '\0';
 173                 syslog(LOG_DEBUG, "from %s (%dbytes): %s",
 174                        direction == 1 ? "client" : "server", tblen, tcpbuf);
 175         }
 176 #endif /* DEBUG */
 177         tblen = 0; tboff = 0;
 178         FD_CLR(s_snd, &writefds);
 179         FD_SET(s_rcv, &readfds);
 180         return;
 181     retry_or_err:
 182         if (errno != EAGAIN)
 183                 exit_failure("writing relay data failed: %s", strerror(errno));
 184         FD_SET(s_snd, &writefds);
 185 }
 186
 187 static void
 188 relay(int s_rcv, int s_snd, const char *service, int direction)
 189 {
 190         int atmark, error, maxfd;
 191         struct timeval tv;
 192         fd_set oreadfds, owritefds, oexceptfds;
 193
 194         FD_ZERO(&readfds);
 195         FD_ZERO(&writefds);
 196         FD_ZERO(&exceptfds);
 197         fcntl(s_snd, F_SETFD, O_NONBLOCK);
 198         oreadfds = readfds; owritefds = writefds; oexceptfds = exceptfds;
 199         FD_SET(s_rcv, &readfds);
 200         FD_SET(s_rcv, &exceptfds);
 201         oob_exists = 0;
 202         maxfd = (s_rcv > s_snd) ? s_rcv : s_snd;
 203
 204         for (;;) {
 205                 tv.tv_sec = FAITH_TIMEOUT / 4;
 206                 tv.tv_usec = 0;
 207                 oreadfds = readfds;
 208                 owritefds = writefds;
 209                 oexceptfds = exceptfds;
 210                 error = select(maxfd + 1, &readfds, &writefds, &exceptfds, &tv);
 211                 if (error == -1) {
 212                         if (errno == EINTR)
 213                                 continue;
 214                         exit_failure("select: %s", strerror(errno));
 215                 } else if (error == 0) {
 216                         readfds = oreadfds;
 217                         writefds = owritefds;
 218                         exceptfds = oexceptfds;
 219                         notify_inactive();
 220                         continue;
 221                 }
 222
 223                 /* activity notification */
 224                 notify_active();
 225
 226                 if (FD_ISSET(s_rcv, &exceptfds)) {
 227                         error = ioctl(s_rcv, SIOCATMARK, &atmark);
 228                         if (error != -1 && atmark == 1) {
 229                                 int cc;
 230                             oob_read_retry:
 231                                 cc = read(s_rcv, atmark_buf, 1);
 232                                 if (cc == 1) {
 233                                         FD_CLR(s_rcv, &exceptfds);
 234                                         FD_SET(s_snd, &writefds);
 235                                         oob_exists = 1;
 236                                 } else if (cc == -1) {
 237                                         if (errno == EINTR)
 238                                                 goto oob_read_retry;
 239                                         exit_failure("reading oob data failed"
 240                                                      ": %s",
 241                                                      strerror(errno));
 242                                 }
 243                         }
 244                 }
 245                 if (FD_ISSET(s_rcv, &readfds)) {
 246                     relaydata_read_retry:
 247                         tblen = read(s_rcv, tcpbuf, sizeof(tcpbuf));
 248                         tboff = 0;
 249
 250                         switch (tblen) {
 251                         case -1:
 252                                 if (errno == EINTR)
 253                                         goto relaydata_read_retry;
 254                                 exit_failure("reading relay data failed: %s",
 255                                              strerror(errno));
 256                                 /* NOTREACHED */
 257                         case 0:
 258                                 /* to close opposite-direction relay process */
 259                                 shutdown(s_snd, SHUT_RD);
 260
 261                                 close(s_rcv);
 262                                 close(s_snd);
 263                                 exit_success("terminating %s relay", service);
 264                                 /* NOTREACHED */
 265                         default:
 266                                 FD_CLR(s_rcv, &readfds);
 267                                 FD_SET(s_snd, &writefds);
 268                                 break;
 269                         }
 270                 }
 271                 if (FD_ISSET(s_snd, &writefds))
 272                         send_data(s_rcv, s_snd, service, direction);
 273         }
 274 }
 275
 276 void
 277 tcp_relay(int s_src, int s_dst, const char *service)
 278 {
 279         syslog(LOG_INFO, "starting %s relay", service);
 280
 281         child_lastactive = parent_lastactive = time(NULL);
 282
 283         cpid = fork();
 284         switch (cpid) {
 285         case -1:
 286                 exit_failure("tcp_relay: can't fork grand child: %s",
 287                     strerror(errno));
 288                 /* NOTREACHED */
 289         case 0:
 290                 /* child process: relay going traffic */
 291                 ppid = getppid();
 292                 /* this is child so reopen log */
 293                 closelog();
 294                 openlog(logname, LOG_PID | LOG_NOWAIT, LOG_DAEMON);
 295                 relay(s_src, s_dst, service, 1);
 296                 /* NOTREACHED */
 297         default:
 298                 /* parent process: relay coming traffic */
 299                 ppid = (pid_t)0;
 300                 signal(SIGUSR1, sig_ctimeout);
 301                 signal(SIGCHLD, sig_child);
 302                 relay(s_dst, s_src, service, 0);
 303                 /* NOTREACHED */
 304         }
 305 }