2 This file is part of GNUnet.
3 Copyright (C) 2010, 2012 Christian Grothoff
5 GNUnet is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 3, or (at your
8 option) any later version.
10 GNUnet is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with GNUnet; see the file COPYING. If not, write to the
17 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA.
22 * @file vpn/gnunet-helper-vpn.c
23 * @brief the helper for the VPN service. Opens a virtual network-interface,
24 * sends data received on the if to stdout, sends data received on stdin to the
26 * @author Philipp Tölke
27 * @author Christian Grothoff
29 * The following list of people have reviewed this code and considered
30 * it safe since the last modification (if you reviewed it, please
31 * have your name added to the list):
36 #include <linux/if_tun.h>
39 * Need 'struct GNUNET_MessageHeader'.
41 #include "gnunet_crypto_lib.h"
42 #include "gnunet_common.h"
45 * Need VPN message types.
47 #include "gnunet_protocols.h"
50 * Should we print (interesting|debug) messages that can happen during
53 #define DEBUG GNUNET_NO
56 * Maximum size of a GNUnet message (GNUNET_SERVER_MAX_MESSAGE_SIZE)
58 #define MAX_SIZE 65536
62 * This is in linux/include/net/ipv6.h, but not always exported...
66 struct in6_addr ifr6_addr;
67 uint32_t ifr6_prefixlen;
68 unsigned int ifr6_ifindex;
74 * Creates a tun-interface called dev;
76 * @param dev is asumed to point to a char[IFNAMSIZ]
77 * if *dev == '\\0', uses the name supplied by the kernel;
78 * @return the fd to the tun or -1 on error
92 if (-1 == (fd = open ("/dev/net/tun", O_RDWR)))
94 fprintf (stderr, "Error opening `%s': %s\n", "/dev/net/tun",
101 fprintf (stderr, "File descriptor to large: %d", fd);
106 memset (&ifr, 0, sizeof (ifr));
107 ifr.ifr_flags = IFF_TUN;
110 strncpy (ifr.ifr_name, dev, IFNAMSIZ);
112 if (-1 == ioctl (fd, TUNSETIFF, (void *) &ifr))
115 "Error with ioctl on `%s': %s\n",
121 strcpy (dev, ifr.ifr_name);
127 * @brief Sets the IPv6-Address given in address on the interface dev
129 * @param dev the interface to configure
130 * @param address the IPv6-Address
131 * @param prefix_len the length of the network-prefix
134 set_address6 (const char *dev, const char *address, unsigned long prefix_len)
137 struct in6_ifreq ifr6;
138 struct sockaddr_in6 sa6;
142 * parse the new address
144 memset (&sa6, 0, sizeof (struct sockaddr_in6));
145 sa6.sin6_family = AF_INET6;
146 if (1 != inet_pton (AF_INET6, address, sa6.sin6_addr.s6_addr))
149 "Failed to parse IPv6 address `%s'\n",
154 if (-1 == (fd = socket (PF_INET6, SOCK_DGRAM, 0)))
157 "Error creating socket: %s\n",
162 memset (&ifr, 0, sizeof (struct ifreq));
164 * Get the index of the if
166 strncpy (ifr.ifr_name, dev, IFNAMSIZ);
167 if (-1 == ioctl (fd, SIOGIFINDEX, &ifr))
169 fprintf (stderr, "ioctl failed at %d: %s\n", __LINE__, strerror (errno));
174 memset (&ifr6, 0, sizeof (struct in6_ifreq));
175 ifr6.ifr6_addr = sa6.sin6_addr;
176 ifr6.ifr6_ifindex = ifr.ifr_ifindex;
177 ifr6.ifr6_prefixlen = prefix_len;
182 if (-1 == ioctl (fd, SIOCSIFADDR, &ifr6))
184 fprintf (stderr, "ioctl failed at line %d: %s\n", __LINE__,
193 if (-1 == ioctl (fd, SIOCGIFFLAGS, &ifr))
195 fprintf (stderr, "ioctl failed at line %d: %s\n", __LINE__,
202 * Add the UP and RUNNING flags
204 ifr.ifr_flags |= IFF_UP | IFF_RUNNING;
205 if (-1 == ioctl (fd, SIOCSIFFLAGS, &ifr))
207 fprintf (stderr, "ioctl failed at line %d: %s\n", __LINE__,
215 fprintf (stderr, "close failed: %s\n", strerror (errno));
222 * @brief Sets the IPv4-Address given in address on the interface dev
224 * @param dev the interface to configure
225 * @param address the IPv4-Address
226 * @param mask the netmask
229 set_address4 (const char *dev, const char *address, const char *mask)
232 struct sockaddr_in *addr;
235 memset (&ifr, 0, sizeof (struct ifreq));
236 addr = (struct sockaddr_in *) &(ifr.ifr_addr);
237 addr->sin_family = AF_INET;
242 if (1 != inet_pton (AF_INET, address, &addr->sin_addr.s_addr))
245 "Failed to parse IPv4 address `%s'\n",
250 if (-1 == (fd = socket (PF_INET, SOCK_DGRAM, 0)))
253 "Error creating socket: %s\n",
258 strncpy (ifr.ifr_name, dev, IFNAMSIZ);
263 if (-1 == ioctl (fd, SIOCSIFADDR, &ifr))
266 "ioctl failed at %d: %s\n",
276 addr = (struct sockaddr_in *) &(ifr.ifr_netmask);
277 if (1 != inet_pton (AF_INET, mask, &addr->sin_addr.s_addr))
280 "Failed to parse IPv4 address mask `%s'\n",
289 if (-1 == ioctl (fd, SIOCSIFNETMASK, &ifr))
292 "ioctl failed at line %d: %s\n",
302 if (-1 == ioctl (fd, SIOCGIFFLAGS, &ifr))
304 fprintf (stderr, "ioctl failed at line %d: %s\n", __LINE__,
311 * Add the UP and RUNNING flags
313 ifr.ifr_flags |= IFF_UP | IFF_RUNNING;
314 if (-1 == ioctl (fd, SIOCSIFFLAGS, &ifr))
316 fprintf (stderr, "ioctl failed at line %d: %s\n", __LINE__,
324 fprintf (stderr, "close failed: %s\n", strerror (errno));
332 * Start forwarding to and from the tunnel.
334 * @param fd_tun tunnel FD
340 * The buffer filled by reading from fd_tun
342 unsigned char buftun[MAX_SIZE];
343 ssize_t buftun_size = 0;
344 unsigned char *buftun_read = NULL;
347 * The buffer filled by reading from stdin
349 unsigned char bufin[MAX_SIZE];
350 ssize_t bufin_size = 0;
351 size_t bufin_rpos = 0;
352 unsigned char *bufin_read = NULL;
357 /* read refers to reading from fd_tun, writing to stdout */
360 /* write refers to reading from stdin, writing to fd_tun */
363 while ((1 == read_open) && (1 == write_open))
369 * We are supposed to read and the buffer is empty
370 * -> select on read from tun
372 if (read_open && (0 == buftun_size))
373 FD_SET (fd_tun, &fds_r);
376 * We are supposed to read and the buffer is not empty
377 * -> select on write to stdout
379 if (read_open && (0 != buftun_size))
383 * We are supposed to write and the buffer is empty
384 * -> select on read from stdin
386 if (write_open && (NULL == bufin_read))
390 * We are supposed to write and the buffer is not empty
391 * -> select on write to tun
393 if (write_open && (NULL != bufin_read))
394 FD_SET (fd_tun, &fds_w);
396 int r = select (fd_tun + 1, &fds_r, &fds_w, NULL, NULL);
402 fprintf (stderr, "select failed: %s\n", strerror (errno));
408 if (FD_ISSET (fd_tun, &fds_r))
411 read (fd_tun, buftun + sizeof (struct GNUNET_MessageHeader),
412 MAX_SIZE - sizeof (struct GNUNET_MessageHeader));
413 if (-1 == buftun_size)
418 shutdown (fd_tun, SHUT_RD);
419 shutdown (1, SHUT_WR);
423 else if (0 == buftun_size)
425 fprintf (stderr, "EOF on tun\n");
426 shutdown (fd_tun, SHUT_RD);
427 shutdown (1, SHUT_WR);
433 buftun_read = buftun;
434 struct GNUNET_MessageHeader *hdr =
435 (struct GNUNET_MessageHeader *) buftun;
436 buftun_size += sizeof (struct GNUNET_MessageHeader);
437 hdr->type = htons (GNUNET_MESSAGE_TYPE_VPN_HELPER);
438 hdr->size = htons (buftun_size);
441 else if (FD_ISSET (1, &fds_w))
443 ssize_t written = write (1, buftun_read, buftun_size);
451 "write-error to stdout: %s\n",
453 shutdown (fd_tun, SHUT_RD);
454 shutdown (1, SHUT_WR);
458 else if (0 == written)
460 fprintf (stderr, "write returned 0!?\n");
465 buftun_size -= written;
466 buftun_read += written;
470 if (FD_ISSET (0, &fds_r))
472 bufin_size = read (0, bufin + bufin_rpos, MAX_SIZE - bufin_rpos);
473 if (-1 == bufin_size)
478 shutdown (0, SHUT_RD);
479 shutdown (fd_tun, SHUT_WR);
483 else if (0 == bufin_size)
486 fprintf (stderr, "EOF on stdin\n");
488 shutdown (0, SHUT_RD);
489 shutdown (fd_tun, SHUT_WR);
495 struct GNUNET_MessageHeader *hdr;
498 bufin_rpos += bufin_size;
499 if (bufin_rpos < sizeof (struct GNUNET_MessageHeader))
501 hdr = (struct GNUNET_MessageHeader *) bufin;
502 if (ntohs (hdr->type) != GNUNET_MESSAGE_TYPE_VPN_HELPER)
504 fprintf (stderr, "protocol violation!\n");
507 if (ntohs (hdr->size) > bufin_rpos)
509 bufin_read = bufin + sizeof (struct GNUNET_MessageHeader);
510 bufin_size = ntohs (hdr->size) - sizeof (struct GNUNET_MessageHeader);
511 bufin_rpos -= bufin_size + sizeof (struct GNUNET_MessageHeader);
514 else if (FD_ISSET (fd_tun, &fds_w))
516 ssize_t written = write (fd_tun, bufin_read, bufin_size);
520 fprintf (stderr, "write-error to tun: %s\n", strerror (errno));
521 shutdown (0, SHUT_RD);
522 shutdown (fd_tun, SHUT_WR);
526 else if (0 == written)
528 fprintf (stderr, "write returned 0!?\n");
533 bufin_size -= written;
534 bufin_read += written;
537 memmove (bufin, bufin_read, bufin_rpos);
538 bufin_read = NULL; /* start reading again */
546 fprintf (stderr, "Exiting select() loop\n");
551 * Open VPN tunnel interface.
553 * @param argc must be 6
554 * @param argv 0: binary name (gnunet-helper-vpn)
555 * 1: tunnel interface name (gnunet-vpn)
556 * 2: IPv6 address (::1), "-" to disable
557 * 3: IPv6 netmask length in bits (64), ignored if #2 is "-"
558 * 4: IPv4 address (1.2.3.4), "-" to disable
559 * 5: IPv4 netmask (255.255.0.0), ignored if #4 is "-"
562 main (int argc, char **argv)
570 fprintf (stderr, "Fatal: must supply 5 arguments!\n");
574 strncpy (dev, argv[1], IFNAMSIZ);
575 dev[IFNAMSIZ - 1] = '\0';
577 if (-1 == (fd_tun = init_tun (dev)))
579 fprintf (stderr, "Fatal: could not initialize tun-interface `%s' with IPv6 %s/%s and IPv4 %s/%s\n",
588 if (0 != strcmp (argv[2], "-"))
590 const char *address = argv[2];
591 long prefix_len = atol (argv[3]);
593 if ((prefix_len < 1) || (prefix_len > 127))
595 fprintf (stderr, "Fatal: prefix_len out of range\n");
599 set_address6 (dev, address, prefix_len);
602 if (0 != strcmp (argv[4], "-"))
604 const char *address = argv[4];
605 const char *mask = argv[5];
607 set_address4 (dev, address, mask);
610 uid_t uid = getuid ();
611 #ifdef HAVE_SETRESUID
612 if (0 != setresuid (uid, uid, uid))
614 fprintf (stderr, "Failed to setresuid: %s\n", strerror (errno));
619 if (0 != (setuid (uid) | seteuid (uid)))
621 fprintf (stderr, "Failed to setuid: %s\n", strerror (errno));
627 if (SIG_ERR == signal (SIGPIPE, SIG_IGN))
629 fprintf (stderr, "Failed to protect against SIGPIPE: %s\n",
631 /* no exit, we might as well die with SIGPIPE should it ever happen */