libexec/ftp-proxy/util.c

   1 /*      $OpenBSD: util.c,v 1.18 2004/01/22 16:10:30 beck Exp $ */
   2 /*      $DragonFly: src/libexec/ftp-proxy/util.c,v 1.2 2005/02/24 15:38:09 joerg Exp $ */
   3
   4 /*
   5  * Copyright (c) 1996-2001
   6  *      Obtuse Systems Corporation.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the Obtuse Systems nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE OBTUSE SYSTEMS AND CONTRIBUTORS
  21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  23  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL OBTUSE
  24  * SYSTEMS CORPORATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
  25  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  26  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  27  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  29  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  30  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  31  * OF THE POSSIBILITY OF SUCH DAMAGE.
  32  *
  33  */
  34
  35 #include <sys/types.h>
  36 #include <sys/socket.h>
  37 #include <sys/ioctl.h>
  38 #include <sys/file.h>
  39 #include <netinet/in.h>
  40 #include <netinet/in_systm.h>
  41 #include <net/if.h>
  42 #include <net/pf/pfvar.h>
  43
  44 #include <arpa/inet.h>
  45
  46 #include <ctype.h>
  47 #include <errno.h>
  48 #include <netdb.h>
  49 #include <signal.h>
  50 #include <stdio.h>
  51 #include <stdlib.h>
  52 #include <string.h>
  53 #include <stdarg.h>
  54 #include <sysexits.h>
  55 #include <syslog.h>
  56 #include <unistd.h>
  57
  58 #include "util.h"
  59
  60 extern int ReverseMode;
  61
  62 int Debug_Level;
  63 int Use_Rdns;
  64 in_addr_t Bind_Addr = INADDR_NONE;
  65
  66 void            debuglog(int debug_level, const char *fmt, ...);
  67
  68 void
  69 debuglog(int debug_level, const char *fmt, ...)
  70 {
  71         va_list ap;
  72         va_start(ap, fmt);
  73
  74         if (Debug_Level >= debug_level)
  75                 vsyslog(LOG_DEBUG, fmt, ap);
  76         va_end(ap);
  77 }
  78
  79 int
  80 get_proxy_env(int connected_fd, struct sockaddr_in *real_server_sa_ptr,
  81     struct sockaddr_in *client_sa_ptr, struct sockaddr_in *proxy_sa_ptr)
  82 {
  83         struct pfioc_natlook natlook;
  84         socklen_t slen;
  85         int fd;
  86
  87         slen = sizeof(*proxy_sa_ptr);
  88         if (getsockname(connected_fd, (struct sockaddr *)proxy_sa_ptr,
  89             &slen) != 0) {
  90                 syslog(LOG_ERR, "getsockname() failed (%m)");
  91                 return(-1);
  92         }
  93         slen = sizeof(*client_sa_ptr);
  94         if (getpeername(connected_fd, (struct sockaddr *)client_sa_ptr,
  95             &slen) != 0) {
  96                 syslog(LOG_ERR, "getpeername() failed (%m)");
  97                 return(-1);
  98         }
  99
 100         if (ReverseMode)
 101                 return(0);
 102
 103         /*
 104          * Build up the pf natlook structure.
 105          * Just for IPv4 right now
 106          */
 107         memset((void *)&natlook, 0, sizeof(natlook));
 108         natlook.af = AF_INET;
 109         natlook.saddr.addr32[0] = client_sa_ptr->sin_addr.s_addr;
 110         natlook.daddr.addr32[0] = proxy_sa_ptr->sin_addr.s_addr;
 111         natlook.proto = IPPROTO_TCP;
 112         natlook.sport = client_sa_ptr->sin_port;
 113         natlook.dport = proxy_sa_ptr->sin_port;
 114         natlook.direction = PF_OUT;
 115
 116         /*
 117          * Open the pf device and lookup the mapping pair to find
 118          * the original address we were supposed to connect to.
 119          */
 120         fd = open("/dev/pf", O_RDWR);
 121         if (fd == -1) {
 122                 syslog(LOG_ERR, "cannot open /dev/pf (%m)");
 123                 exit(EX_UNAVAILABLE);
 124         }
 125
 126         if (ioctl(fd, DIOCNATLOOK, &natlook) == -1) {
 127                 syslog(LOG_INFO,
 128                     "pf nat lookup failed %s:%hu (%m)",
 129                     inet_ntoa(client_sa_ptr->sin_addr),
 130                     ntohs(client_sa_ptr->sin_port));
 131                 close(fd);
 132                 return(-1);
 133         }
 134         close(fd);
 135
 136         /*
 137          * Now jam the original address and port back into the into
 138          * destination sockaddr_in for the proxy to deal with.
 139          */
 140         memset((void *)real_server_sa_ptr, 0, sizeof(struct sockaddr_in));
 141         real_server_sa_ptr->sin_port = natlook.rdport;
 142         real_server_sa_ptr->sin_addr.s_addr = natlook.rdaddr.addr32[0];
 143         real_server_sa_ptr->sin_len = sizeof(struct sockaddr_in);
 144         real_server_sa_ptr->sin_family = AF_INET;
 145         return(0);
 146 }
 147
 148
 149 /*
 150  * Transfer one unit of data across a pair of sockets
 151  *
 152  * A unit of data is as much as we get with a single read(2) call.
 153  */
 154 int
 155 xfer_data(const char *what_read,int from_fd, int to_fd,
 156           struct in_addr from __unused, struct in_addr to __unused)
 157 {
 158         int rlen, offset, xerrno, mark, flags = 0;
 159         char tbuf[4096];
 160
 161         /*
 162          * Are we at the OOB mark?
 163          */
 164         if (ioctl(from_fd, SIOCATMARK, &mark) < 0) {
 165                 xerrno = errno;
 166                 syslog(LOG_ERR, "cannot ioctl(SIOCATMARK) socket from %s (%m)",
 167                     what_read);
 168                 errno = xerrno;
 169                 return(-1);
 170         }
 171         if (mark)
 172                 flags = MSG_OOB;        /* Yes - at the OOB mark */
 173
 174 snarf:
 175         rlen = recv(from_fd, tbuf, sizeof(tbuf), flags);
 176         if (rlen == -1 && flags == MSG_OOB && errno == EINVAL) {
 177                 /* OOB didn't work */
 178                 flags = 0;
 179                 rlen = recv(from_fd, tbuf, sizeof(tbuf), flags);
 180         }
 181         if (rlen == 0) {
 182                 debuglog(3, "EOF on read socket");
 183                 return(0);
 184         } else if (rlen == -1) {
 185                 if (errno == EAGAIN || errno == EINTR)
 186                         goto snarf;
 187                 xerrno = errno;
 188                 syslog(LOG_ERR, "xfer_data (%s): failed (%m) with flags 0%o",
 189                     what_read, flags);
 190                 errno = xerrno;
 191                 return(-1);
 192         } else {
 193                 offset = 0;
 194                 debuglog(3, "got %d bytes from socket", rlen);
 195
 196                 while (offset < rlen) {
 197                         int wlen;
 198                 fling:
 199                         wlen = send(to_fd, &tbuf[offset], rlen - offset,
 200                             flags);
 201                         if (wlen == 0) {
 202                                 debuglog(3, "zero-length write");
 203                                 goto fling;
 204                         } else if (wlen == -1) {
 205                                 if (errno == EAGAIN || errno == EINTR)
 206                                         goto fling;
 207                                 xerrno = errno;
 208                                 syslog(LOG_INFO, "write failed (%m)");
 209                                 errno = xerrno;
 210                                 return(-1);
 211                         } else {
 212                                 debuglog(3, "wrote %d bytes to socket",wlen);
 213                                 offset += wlen;
 214                         }
 215                 }
 216                 return(offset);
 217         }
 218 }
 219
 220 /*
 221  * get_backchannel_socket gets us a socket bound somewhere in a
 222  * particular range of ports
 223  */
 224 int
 225 get_backchannel_socket(int type, int min_port, int max_port, int start_port,
 226     int direction, struct sockaddr_in *sap)
 227 {
 228         int count;
 229
 230         /*
 231          * Make sure that direction is 'defined' and that min_port is not
 232          * greater than max_port.
 233          */
 234         if (direction != -1)
 235                 direction = 1;
 236
 237         /* by default we go up by one port until we find one */
 238         if (min_port > max_port) {
 239                 errno = EINVAL;
 240                 return(-1);
 241         }
 242
 243         count = 1 + max_port - min_port;
 244
 245         /*
 246          * Pick a port we can bind to from within the range we want.
 247          * If the caller specifies -1 as the starting port number then
 248          * we pick one somewhere in the range to try.
 249          * This is an optimization intended to speedup port selection and
 250          * has NOTHING to do with security.
 251          */
 252         if (start_port == -1)
 253                 start_port = (arc4random() % count) + min_port;
 254
 255         if (start_port < min_port || start_port > max_port) {
 256                 errno = EINVAL;
 257                 return(-1);
 258         }
 259
 260         while (count-- > 0) {
 261                 struct sockaddr_in sa;
 262                 int one, fd;
 263
 264                 fd = socket(AF_INET, type, 0);
 265
 266                 bzero(&sa, sizeof sa);
 267                 sa.sin_family = AF_INET;
 268                 if (Bind_Addr == INADDR_NONE)
 269                         if (sap == NULL)
 270                                 sa.sin_addr.s_addr = INADDR_ANY;
 271                         else
 272                                 sa.sin_addr.s_addr = sap->sin_addr.s_addr;
 273                 else
 274                         sa.sin_addr.s_addr = Bind_Addr;
 275
 276                 /*
 277                  * Indicate that we want to reuse a port if it happens that the
 278                  * port in question was a listen port recently.
 279                  */
 280                 one = 1;
 281                 if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one,
 282                     sizeof(one))  == -1)
 283                         return(-1);
 284
 285                 sa.sin_port = htons(start_port);
 286
 287                 if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) == 0) {
 288                         if (sap != NULL)
 289                                 *sap = sa;
 290                         return(fd);
 291                 }
 292
 293                 if (errno != EADDRINUSE)
 294                         return(-1);
 295
 296                 /* if it's in use, try the next port */
 297                 close(fd);
 298
 299                 start_port += direction;
 300                 if (start_port < min_port)
 301                         start_port = max_port;
 302                 else if (start_port > max_port)
 303                         start_port = min_port;
 304         }
 305         errno = EAGAIN;
 306         return(-1);
 307 }