-towards new exit daemon

1 files changed, 596 insertions, 0 deletions

diff --git a/src/exit/gnunet-helper-exit.c b/src/exit/gnunet-helper-exit.c
new file mode 100644
index 000000000..b93ce2382
--- /dev/null
+++ b/src/exit/gnunet-helper-exit.c
@@ -0,0 +1,596 @@
+/*
+     This file is part of GNUnet.
+     (C) 2010 Christian Grothoff
+
+     GNUnet is free software; you can redistribute it and/or modify
+     it under the terms of the GNU General Public License as published
+     by the Free Software Foundation; either version 3, or (at your
+     option) any later version.
+
+     GNUnet is distributed in the hope that it will be useful, but
+     WITHOUT ANY WARRANTY; without even the implied warranty of
+     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+     General Public License for more details.
+
+     You should have received a copy of the GNU General Public License
+     along with GNUnet; see the file COPYING.  If not, write to the
+     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+     Boston, MA 02111-1307, USA.
+*/
+
+/**
+ * @file vpn/gnunet-daemon-vpn.c
+ * @brief the helper for various vpn-daemons. Opens a virtual network-interface,
+ * sends data received on the if to stdout, sends data received on stdin to the
+ * interface
+ * @author Philipp Tölke
+ *
+ * The following list of people have reviewed this code and considered
+ * it safe since the last modification (if you reviewed it, please
+ * have your name added to the list):
+ *
+ * - Philipp Tölke
+ */
+#include "platform.h"
+#include <linux/if_tun.h>
+
+/**
+ * Need 'struct GNUNET_MessageHeader'.
+ */
+#include "gnunet_common.h"
+
+/**
+ * Need VPN message types.
+ */
+#include "gnunet_protocols.h"
+
+/**
+ * Maximum size of a GNUnet message (GNUNET_SERVER_MAX_MESSAGE_SIZE)
+ */
+#define MAX_SIZE 65536
+
+#ifndef _LINUX_IN6_H
+/**
+ * This is in linux/include/net/ipv6.h, but not always exported...
+ */
+struct in6_ifreq
+{
+  struct in6_addr ifr6_addr;
+  uint32_t ifr6_prefixlen;
+  unsigned int ifr6_ifindex;
+};
+#endif
+
+
+/**
+ * Creates a tun-interface called dev;
+ *
+ * @param dev is asumed to point to a char[IFNAMSIZ]
+ *        if *dev == '\\0', uses the name supplied by the kernel;
+ * @return the fd to the tun or -1 on error
+ */
+static int
+init_tun (char *dev)
+{
+  struct ifreq ifr;
+  int fd;
+
+  if (NULL == dev)
+  {
+    errno = EINVAL;
+    return -1;
+  }
+
+  if (-1 == (fd = open ("/dev/net/tun", O_RDWR)))
+  {
+    fprintf (stderr, "Error opening `%s': %s\n", "/dev/net/tun",
+             strerror (errno));
+    return -1;
+  }
+
+  if (fd >= FD_SETSIZE)
+  {
+    fprintf (stderr, "File descriptor to large: %d", fd);
+    return -1;
+  }
+
+  memset (&ifr, 0, sizeof (ifr));
+  ifr.ifr_flags = IFF_TUN;
+
+  if ('\0' != *dev)
+    strncpy (ifr.ifr_name, dev, IFNAMSIZ);
+
+  if (-1 == ioctl (fd, TUNSETIFF, (void *) &ifr))
+  {
+    fprintf (stderr, "Error with ioctl on `%s': %s\n", "/dev/net/tun",
+             strerror (errno));
+    (void) close (fd);
+    return -1;
+  }
+  strcpy (dev, ifr.ifr_name);
+  return fd;
+}
+
+
+/**
+ * @brief Sets the IPv6-Address given in address on the interface dev
+ *
+ * @param dev the interface to configure
+ * @param address the IPv6-Address
+ * @param prefix_len the length of the network-prefix
+ */
+static void
+set_address6 (const char *dev, const char *address, unsigned long prefix_len)
+{
+  struct ifreq ifr;
+  struct in6_ifreq ifr6;
+  struct sockaddr_in6 sa6;
+  int fd;
+
+  /*
+   * parse the new address
+   */
+  memset (&sa6, 0, sizeof (struct sockaddr_in6));
+  sa6.sin6_family = AF_INET6;
+  if (1 != inet_pton (AF_INET6, address, sa6.sin6_addr.s6_addr))
+  {
+    fprintf (stderr, "Failed to parse address `%s': %s\n", address,
+             strerror (errno));
+    exit (1);
+  }
+
+  if (-1 == (fd = socket (PF_INET6, SOCK_DGRAM, 0)))
+  {
+    fprintf (stderr, "Error creating socket: %s\n", strerror (errno));
+    exit (1);
+  }
+
+  memset (&ifr, 0, sizeof (struct ifreq));
+  /*
+   * Get the index of the if
+   */
+  strncpy (ifr.ifr_name, dev, IFNAMSIZ);
+  if (-1 == ioctl (fd, SIOGIFINDEX, &ifr))
+  {
+    fprintf (stderr, "ioctl failed at %d: %s\n", __LINE__, strerror (errno));
+    (void) close (fd);
+    exit (1);
+  }
+
+  memset (&ifr6, 0, sizeof (struct in6_ifreq));
+  ifr6.ifr6_addr = sa6.sin6_addr;
+  ifr6.ifr6_ifindex = ifr.ifr_ifindex;
+  ifr6.ifr6_prefixlen = prefix_len;
+
+  /*
+   * Set the address
+   */
+  if (-1 == ioctl (fd, SIOCSIFADDR, &ifr6))
+  {
+    fprintf (stderr, "ioctl failed at line %d: %s\n", __LINE__,
+             strerror (errno));
+    (void) close (fd);
+    exit (1);
+  }
+
+  /*
+   * Get the flags
+   */
+  if (-1 == ioctl (fd, SIOCGIFFLAGS, &ifr))
+  {
+    fprintf (stderr, "ioctl failed at line %d: %s\n", __LINE__,
+             strerror (errno));
+    (void) close (fd);
+    exit (1);
+  }
+
+  /*
+   * Add the UP and RUNNING flags
+   */
+  ifr.ifr_flags |= IFF_UP | IFF_RUNNING;
+  if (-1 == ioctl (fd, SIOCSIFFLAGS, &ifr))
+  {
+    fprintf (stderr, "ioctl failed at line %d: %s\n", __LINE__,
+             strerror (errno));
+    (void) close (fd);
+    exit (1);
+  }
+
+  if (0 != close (fd))
+  {
+    fprintf (stderr, "close failed: %s\n", strerror (errno));
+    exit (1);
+  }
+}
+
+
+/**
+ * @brief Sets the IPv4-Address given in address on the interface dev
+ *
+ * @param dev the interface to configure
+ * @param address the IPv4-Address
+ * @param mask the netmask
+ */
+static void
+set_address4 (const char *dev, const char *address, const char *mask)
+{
+  int fd;
+  struct sockaddr_in *addr;
+  struct ifreq ifr;
+
+  memset (&ifr, 0, sizeof (struct ifreq));
+  addr = (struct sockaddr_in *) &(ifr.ifr_addr);
+  addr->sin_family = AF_INET;
+
+  /*
+   * Parse the address
+   */
+  if (1 != inet_pton (AF_INET, address, &addr->sin_addr.s_addr))
+  {
+    fprintf (stderr, "Failed to parse address `%s': %s\n", address,
+             strerror (errno));
+    exit (1);
+  }
+
+  if (-1 == (fd = socket (PF_INET, SOCK_DGRAM, 0)))
+  {
+    fprintf (stderr, "Error creating socket: %s\n", strerror (errno));
+    exit (1);
+  }
+
+  strncpy (ifr.ifr_name, dev, IFNAMSIZ);
+
+  /*
+   * Set the address
+   */
+  if (-1 == ioctl (fd, SIOCSIFADDR, &ifr))
+  {
+    fprintf (stderr, "ioctl failed at %d: %s\n", __LINE__, strerror (errno));
+    (void) close (fd);
+    exit (1);
+  }
+
+  /*
+   * Parse the netmask
+   */
+  addr = (struct sockaddr_in *) &(ifr.ifr_netmask);
+  if (1 != inet_pton (AF_INET, mask, &addr->sin_addr.s_addr))
+  {
+    fprintf (stderr, "Failed to parse address `%s': %s\n", mask,
+             strerror (errno));
+    (void) close (fd);
+    exit (1);
+  }
+
+  /*
+   * Set the netmask
+   */
+  if (-1 == ioctl (fd, SIOCSIFNETMASK, &ifr))
+  {
+    fprintf (stderr, "ioctl failed at line %d: %s\n", __LINE__,
+             strerror (errno));
+    (void) close (fd);
+    exit (1);
+  }
+
+  /*
+   * Get the flags
+   */
+  if (-1 == ioctl (fd, SIOCGIFFLAGS, &ifr))
+  {
+    fprintf (stderr, "ioctl failed at line %d: %s\n", __LINE__,
+             strerror (errno));
+    (void) close (fd);
+    exit (1);
+  }
+
+  /*
+   * Add the UP and RUNNING flags
+   */
+  ifr.ifr_flags |= IFF_UP | IFF_RUNNING;
+  if (-1 == ioctl (fd, SIOCSIFFLAGS, &ifr))
+  {
+    fprintf (stderr, "ioctl failed at line %d: %s\n", __LINE__,
+             strerror (errno));
+    (void) close (fd);
+    exit (1);
+  }
+
+  if (0 != close (fd))
+  {
+    fprintf (stderr, "close failed: %s\n", strerror (errno));
+    (void) close (fd);
+    exit (1);
+  }
+}
+
+
+/**
+ * Start forwarding to and from the tunnel.
+ *
+ * @param fd_tun tunnel FD
+ */
+static void
+run (int fd_tun)
+{
+  /*
+   * The buffer filled by reading from fd_tun
+   */
+  unsigned char buftun[MAX_SIZE];
+  ssize_t buftun_size = 0;
+  unsigned char *buftun_read = NULL;
+
+  /*
+   * The buffer filled by reading from stdin
+   */
+  unsigned char bufin[MAX_SIZE];
+  ssize_t bufin_size = 0;
+  size_t bufin_rpos = 0;
+  unsigned char *bufin_read = NULL;
+
+  fd_set fds_w;
+  fd_set fds_r;
+
+  /* read refers to reading from fd_tun, writing to stdout */
+  int read_open = 1;
+
+  /* write refers to reading from stdin, writing to fd_tun */
+  int write_open = 1;
+
+  while ((1 == read_open) || (1 == write_open))
+  {
+    FD_ZERO (&fds_w);
+    FD_ZERO (&fds_r);
+
+    /*
+     * We are supposed to read and the buffer is empty
+     * -> select on read from tun
+     */
+    if (read_open && (0 == buftun_size))
+      FD_SET (fd_tun, &fds_r);
+
+    /*
+     * We are supposed to read and the buffer is not empty
+     * -> select on write to stdout
+     */
+    if (read_open && (0 != buftun_size))
+      FD_SET (1, &fds_w);
+
+    /*
+     * We are supposed to write and the buffer is empty
+     * -> select on read from stdin
+     */
+    if (write_open && (NULL == bufin_read))
+      FD_SET (0, &fds_r);
+
+    /*
+     * We are supposed to write and the buffer is not empty
+     * -> select on write to tun
+     */
+    if (write_open && (NULL != bufin_read))
+      FD_SET (fd_tun, &fds_w);
+
+    int r = select (fd_tun + 1, &fds_r, &fds_w, NULL, NULL);
+
+    if (-1 == r)
+    {
+      if (EINTR == errno)
+        continue;
+      fprintf (stderr, "select failed: %s\n", strerror (errno));
+      exit (1);
+    }
+
+    if (r > 0)
+    {
+      if (FD_ISSET (fd_tun, &fds_r))
+      {
+        buftun_size =
+            read (fd_tun, buftun + sizeof (struct GNUNET_MessageHeader),
+                  MAX_SIZE - sizeof (struct GNUNET_MessageHeader));
+        if (-1 == buftun_size)
+        {
+          fprintf (stderr, "read-error: %s\n", strerror (errno));
+          shutdown (fd_tun, SHUT_RD);
+          shutdown (1, SHUT_WR);
+          read_open = 0;
+          buftun_size = 0;
+        }
+        else if (0 == buftun_size)
+        {
+          fprintf (stderr, "EOF on tun\n");
+          shutdown (fd_tun, SHUT_RD);
+          shutdown (1, SHUT_WR);
+          read_open = 0;
+          buftun_size = 0;
+        }
+        else
+        {
+          buftun_read = buftun;
+          struct GNUNET_MessageHeader *hdr =
+              (struct GNUNET_MessageHeader *) buftun;
+          buftun_size += sizeof (struct GNUNET_MessageHeader);
+          hdr->type = htons (GNUNET_MESSAGE_TYPE_VPN_HELPER);
+          hdr->size = htons (buftun_size);
+        }
+      }
+      else if (FD_ISSET (1, &fds_w))
+      {
+        ssize_t written = write (1, buftun_read, buftun_size);
+
+        if (-1 == written)
+        {
+          fprintf (stderr, "write-error to stdout: %s\n", strerror (errno));
+          shutdown (fd_tun, SHUT_RD);
+          shutdown (1, SHUT_WR);
+          read_open = 0;
+          buftun_size = 0;
+        }
+        else if (0 == written)
+        {
+          fprintf (stderr, "write returned 0!?\n");
+          exit (1);
+        }
+        else
+        {
+          buftun_size -= written;
+          buftun_read += written;
+        }
+      }
+
+      if (FD_ISSET (0, &fds_r))
+      {
+        bufin_size = read (0, bufin + bufin_rpos, MAX_SIZE - bufin_rpos);
+        if (-1 == bufin_size)
+        {
+          fprintf (stderr, "read-error: %s\n", strerror (errno));
+          shutdown (0, SHUT_RD);
+          shutdown (fd_tun, SHUT_WR);
+          write_open = 0;
+          bufin_size = 0;
+        }
+        else if (0 == bufin_size)
+        {
+          fprintf (stderr, "EOF on stdin\n");
+          shutdown (0, SHUT_RD);
+          shutdown (fd_tun, SHUT_WR);
+          write_open = 0;
+          bufin_size = 0;
+        }
+        else
+        {
+          struct GNUNET_MessageHeader *hdr;
+
+PROCESS_BUFFER:
+          bufin_rpos += bufin_size;
+          if (bufin_rpos < sizeof (struct GNUNET_MessageHeader))
+            continue;
+          hdr = (struct GNUNET_MessageHeader *) bufin;
+          if (ntohs (hdr->type) != GNUNET_MESSAGE_TYPE_VPN_HELPER)
+          {
+            fprintf (stderr, "protocol violation!\n");
+            exit (1);
+          }
+          if (ntohs (hdr->size) > bufin_rpos)
+            continue;
+          bufin_read = bufin + sizeof (struct GNUNET_MessageHeader);
+          bufin_size = ntohs (hdr->size) - sizeof (struct GNUNET_MessageHeader);
+          bufin_rpos -= bufin_size + sizeof (struct GNUNET_MessageHeader);
+        }
+      }
+      else if (FD_ISSET (fd_tun, &fds_w))
+      {
+        ssize_t written = write (fd_tun, bufin_read, bufin_size);
+
+        if (-1 == written)
+        {
+          fprintf (stderr, "write-error to tun: %s\n", strerror (errno));
+          shutdown (0, SHUT_RD);
+          shutdown (fd_tun, SHUT_WR);
+          write_open = 0;
+          bufin_size = 0;
+        }
+        else if (0 == written)
+        {
+          fprintf (stderr, "write returned 0!?\n");
+          exit (1);
+        }
+        else
+        {
+          bufin_size -= written;
+          bufin_read += written;
+          if (0 == bufin_size)
+          {
+            memmove (bufin, bufin_read, bufin_rpos);
+            bufin_read = NULL;  /* start reading again */
+            bufin_size = 0;
+            goto PROCESS_BUFFER;
+          }
+        }
+      }
+    }
+  }
+}
+
+
+/**
+ * Open VPN tunnel interface.
+ *
+ * @param argc must be 6
+ * @param argv 0: binary name (gnunet-helper-vpn)
+ *             1: tunnel interface name (gnunet-vpn)
+ *             2: IPv6 address (::1)
+ *             3: IPv6 netmask length in bits (64)
+ *             4: IPv4 address (1.2.3.4)
+ *             5: IPv4 netmask (255.255.0.0)
+ */
+int
+main (int argc, char **argv)
+{
+  char dev[IFNAMSIZ];
+  int fd_tun;
+  int global_ret;
+
+  if (6 != argc)
+  {
+    fprintf (stderr, "Fatal: must supply 5 arguments!\n");
+    return 1;
+  }
+
+  strncpy (dev, argv[1], IFNAMSIZ);
+  dev[IFNAMSIZ - 1] = '\0';
+
+  if (-1 == (fd_tun = init_tun (dev)))
+  {
+    fprintf (stderr, "Fatal: could not initialize tun-interface\n");
+    return 1;
+  }
+
+  {
+    const char *address = argv[2];
+    long prefix_len = atol (argv[3]);
+
+    if ((prefix_len < 1) || (prefix_len > 127))
+    {
+      fprintf (stderr, "Fatal: prefix_len out of range\n");
+      return 1;
+    }
+
+    set_address6 (dev, address, prefix_len);
+  }
+
+  {
+    const char *address = argv[4];
+    const char *mask = argv[5];
+
+    set_address4 (dev, address, mask);
+  }
+  
+  uid_t uid = getuid ();
+#ifdef HAVE_SETRESUID
+  if (0 != setresuid (uid, uid, uid))
+  {
+    fprintf (stderr, "Failed to setresuid: %s\n", strerror (errno));
+    global_ret = 2;
+    goto cleanup;
+  }
+#else
+  if (0 != (setuid (uid) | seteuid (uid)))
+  {
+    fprintf (stderr, "Failed to setuid: %s\n", strerror (errno));
+    global_ret = 2;
+    goto cleanup;
+  }
+#endif
+
+  if (SIG_ERR == signal (SIGPIPE, SIG_IGN))
+  {
+    fprintf (stderr, "Failed to protect against SIGPIPE: %s\n",
+             strerror (errno));
+    /* no exit, we might as well die with SIGPIPE should it ever happen */
+  }
+  run (fd_tun);
+  global_ret = 0;
+ cleanup:
+  close (fd_tun);
+  return global_ret;
+}