X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=src%2Fnat%2Fgnunet-helper-nat-server.c;h=d3c890b9815ad06e4253af206654ba85223f4e83;hb=f4d040c0f0dd2fef3d73b1f4532c76219f760f75;hp=945c98735d067d090c379d5863d895fa9c0b17ff;hpb=11a2d8cd5b619a0fea63e766585c6ec4687a0707;p=oweals%2Fgnunet.git

diff --git a/src/nat/gnunet-helper-nat-server.c b/src/nat/gnunet-helper-nat-server.c
index 945c98735..d3c890b98 100644
--- a/src/nat/gnunet-helper-nat-server.c
+++ b/src/nat/gnunet-helper-nat-server.c
@@ -40,6 +40,7 @@
  * - Christian Grothoff
  * - Nathan Evans
  * - Benjamin Kuperman (22 Aug 2010)
+ * - Jacob Appelbaum (19 Dec 2011)
  */
 #if HAVE_CONFIG_H
 /* Just needed for HAVE_SOCKADDR_IN_SIN_LEN test macro! */
@@ -69,6 +70,11 @@
  */
 #define VERBOSE 0
 
+/**
+ * Must match packet ID used by gnunet-helper-nat-client.c
+ */
+#define PACKET_ID 256
+
 /**
  * Must match IP given in the client.
  */
@@ -212,17 +218,16 @@ static struct in_addr dummy;
  * @return the CRC 16.
  */
 static uint16_t
-calc_checksum(const uint16_t *data,
-	      unsigned int bytes)
+calc_checksum (const uint16_t * data, unsigned int bytes)
 {
   uint32_t sum;
   unsigned int i;
 
   sum = 0;
-  for (i=0;i<bytes/2;i++)
+  for (i = 0; i < bytes / 2; i++)
     sum += data[i];
   sum = (sum & 0xffff) + (sum >> 16);
-  sum = htons(0xffff - sum);
+  sum = htons (0xffff - sum);
   return sum;
 }
 
@@ -246,29 +251,26 @@ send_icmp_echo (const struct in_addr *my_ip)
   ip_pkt.vers_ihl = 0x45;
   ip_pkt.tos = 0;
   ip_pkt.pkt_len = htons (sizeof (packet));
-  ip_pkt.id = htons (256);
+  ip_pkt.id = htons (PACKET_ID);
   ip_pkt.flags_frag_offset = 0;
   ip_pkt.ttl = IPDEFTTL;
   ip_pkt.proto = IPPROTO_ICMP;
   ip_pkt.checksum = 0;
   ip_pkt.src_ip = my_ip->s_addr;
   ip_pkt.dst_ip = dummy.s_addr;
-  ip_pkt.checksum = htons(calc_checksum((uint16_t*)&ip_pkt,
-					sizeof (struct ip_header)));
-  memcpy (&packet[off],
-	  &ip_pkt,
-	  sizeof (struct ip_header));
+  ip_pkt.checksum =
+      htons (calc_checksum ((uint16_t *) & ip_pkt, sizeof (struct ip_header)));
+  memcpy (&packet[off], &ip_pkt, sizeof (struct ip_header));
   off += sizeof (struct ip_header);
 
   icmp_echo.type = ICMP_ECHO;
   icmp_echo.code = 0;
   icmp_echo.checksum = 0;
   icmp_echo.reserved = 0;
-  icmp_echo.checksum = htons(calc_checksum((uint16_t*)&icmp_echo,
-					   sizeof (struct icmp_echo_header)));
-  memcpy (&packet[off],
-	  &icmp_echo,
-	  sizeof (struct icmp_echo_header));
+  icmp_echo.checksum =
+      htons (calc_checksum
+             ((uint16_t *) & icmp_echo, sizeof (struct icmp_echo_header)));
+  memcpy (&packet[off], &icmp_echo, sizeof (struct icmp_echo_header));
   off += sizeof (struct icmp_echo_header);
 
   memset (&dst, 0, sizeof (dst));
@@ -277,22 +279,18 @@ send_icmp_echo (const struct in_addr *my_ip)
   dst.sin_len = sizeof (struct sockaddr_in);
 #endif
   dst.sin_addr = dummy;
-  err = sendto(rawsock,
-	       packet, off, 0,
-	       (struct sockaddr*)&dst,
-	       sizeof(dst));
+  err =
+      sendto (rawsock, packet, off, 0, (struct sockaddr *) &dst, sizeof (dst));
   if (err < 0)
-    {
+  {
 #if VERBOSE
-      fprintf(stderr,
-	      "sendto failed: %s\n", strerror(errno));
+    fprintf (stderr, "sendto failed: %s\n", strerror (errno));
 #endif
-    }
+  }
   else if (sizeof (packet) != err)
-    {
-      fprintf(stderr,
-	      "Error: partial send of ICMP message\n");
-    }
+  {
+    fprintf (stderr, "Error: partial send of ICMP message\n");
+  }
 }
 
 
@@ -312,22 +310,17 @@ send_udp ()
 #endif
   dst.sin_addr = dummy;
   dst.sin_port = htons (NAT_TRAV_PORT);
-  err = sendto(udpsock,
-	       NULL, 0, 0,
-	       (struct sockaddr*)&dst,
-	       sizeof(dst));
+  err = sendto (udpsock, NULL, 0, 0, (struct sockaddr *) &dst, sizeof (dst));
   if (err < 0)
-    {
+  {
 #if VERBOSE
-      fprintf(stderr,
-	      "sendto failed: %s\n", strerror(errno));
+    fprintf (stderr, "sendto failed: %s\n", strerror (errno));
 #endif
-    }
+  }
   else if (0 != err)
-    {
-      fprintf(stderr,
-	      "Error: partial send of ICMP message\n");
-    }
+  {
+    fprintf (stderr, "Error: partial send of ICMP message\n");
+  }
 }
 
 
@@ -349,178 +342,107 @@ process_icmp_response ()
 
   have = read (icmpsock, buf, sizeof (buf));
   if (-1 == have)
-    {
-      fprintf (stderr,
-	       "Error reading raw socket: %s\n",
-	       strerror (errno));
-      return;
-    }
+  {
+    fprintf (stderr, "Error reading raw socket: %s\n", strerror (errno));
+    return;
+  }
 #if VERBOSE
-  fprintf (stderr,
-           "Received message of %u bytes\n",
-           (unsigned int) have);
+  fprintf (stderr, "Received message of %u bytes\n", (unsigned int) have);
 #endif
-  if (have < (ssize_t) (sizeof (struct ip_header) + sizeof (struct icmp_ttl_exceeded_header) + sizeof (struct ip_header)))
-    {
-      /* malformed */
-      return;
-    }
+  if (have <
+      (ssize_t) (sizeof (struct ip_header) +
+                 sizeof (struct icmp_ttl_exceeded_header) +
+                 sizeof (struct ip_header)))
+  {
+    /* malformed */
+    return;
+  }
   off = 0;
-  memcpy (&ip_pkt,
-	  &buf[off],
-	  sizeof (struct ip_header));
+  memcpy (&ip_pkt, &buf[off], sizeof (struct ip_header));
   off += sizeof (struct ip_header);
-  memcpy(&source_ip,
-	 &ip_pkt.src_ip,
-	 sizeof (source_ip));
-  memcpy (&icmp_ttl,
-	  &buf[off],
-	  sizeof (struct icmp_ttl_exceeded_header));
+  memcpy (&icmp_ttl, &buf[off], sizeof (struct icmp_ttl_exceeded_header));
   off += sizeof (struct icmp_ttl_exceeded_header);
-  if ( (ICMP_TIME_EXCEEDED != icmp_ttl.type) ||
-       (0 != icmp_ttl.code) )
-    {
-      /* different type than what we want */
-      return;
-    }
+  if ((ICMP_TIME_EXCEEDED != icmp_ttl.type) || (0 != icmp_ttl.code))
+  {
+    /* different type than what we want */
+    return;
+  }
   /* skip 2nd IP header */
-  memcpy (&ip_pkt,
-	  &buf[off],
-	  sizeof (struct ip_header));
+  memcpy (&ip_pkt, &buf[off], sizeof (struct ip_header));
   off += sizeof (struct ip_header);
 
   switch (ip_pkt.proto)
+  {
+  case IPPROTO_ICMP:
+    if (have !=
+        (sizeof (struct ip_header) * 2 +
+         sizeof (struct icmp_ttl_exceeded_header) +
+         sizeof (struct icmp_echo_header)))
     {
-    case IPPROTO_ICMP:
-      if (have != (sizeof (struct ip_header) * 2 +
-		   sizeof (struct icmp_ttl_exceeded_header) +
-		   sizeof (struct icmp_echo_header)) )
-	{
-	  /* malformed */
-	  return;
-	}
-      /* grab ICMP ECHO content */
-      memcpy (&icmp_echo,
-	      &buf[off],
-	      sizeof (struct icmp_echo_header));
-      port = (uint16_t)  ntohl (icmp_echo.reserved);
-      break;
-    case IPPROTO_UDP:
-      if (have != (sizeof (struct ip_header) * 2 +
-		   sizeof (struct icmp_ttl_exceeded_header) +
-		   sizeof (struct udp_header)) )
-	{
-	  /* malformed */
-	  return;
-	}
-      /* grab UDP content */
-      memcpy (&udp_pkt,
-	      &buf[off],
-	      sizeof (struct udp_header));
-      port = ntohs (udp_pkt.length);
-      break;
-    default:
-      /* different type than what we want */
+      /* malformed */
       return;
     }
-
+    /* grab ICMP ECHO content */
+    memcpy (&icmp_echo, &buf[off], sizeof (struct icmp_echo_header));
+    port = (uint16_t) ntohl (icmp_echo.reserved);
+    break;
+  case IPPROTO_UDP:
+    if (have !=
+        (sizeof (struct ip_header) * 2 +
+         sizeof (struct icmp_ttl_exceeded_header) + sizeof (struct udp_header)))
+    {
+      /* malformed */
+      return;
+    }
+    /* grab UDP content */
+    memcpy (&udp_pkt, &buf[off], sizeof (struct udp_header));
+    port = ntohs (udp_pkt.length);
+    break;
+  default:
+    /* different type than what we want */
+    return;
+  }
+
+  source_ip.s_addr = ip_pkt.src_ip;
   if (port == 0)
-    fprintf (stdout,
-	     "%s\n",
-	     inet_ntop (AF_INET,
-			&source_ip,
-			buf,
-			sizeof (buf)));
+    fprintf (stdout, "%s\n",
+             inet_ntop (AF_INET, &source_ip, buf, sizeof (buf)));
   else
-    fprintf (stdout,
-	     "%s:%u\n",
-	     inet_ntop (AF_INET,
-			&source_ip,
-			buf,
-			sizeof (buf)),
-	     (unsigned int) port);
+    fprintf (stdout, "%s:%u\n",
+             inet_ntop (AF_INET, &source_ip, buf, sizeof (buf)),
+             (unsigned int) port);
   fflush (stdout);
 }
 
 
 /**
- * Create an ICMP raw socket for reading.
+ * Fully initialize the raw socket.
  *
- * @return -1 on error
+ * @return -1 on error, 0 on success
  */
 static int
-make_icmp_socket ()
-{
-  int ret;
-
-  ret = socket (AF_INET, SOCK_RAW, IPPROTO_ICMP);
-  if (-1 == ret)
-    {
-      fprintf (stderr,
-	       "Error opening RAW socket: %s\n",
-	       strerror (errno));
-      return -1;
-    }
-  if (ret >= FD_SETSIZE)
-    {
-      fprintf (stderr,
-	       "Socket number too large (%d > %u)\n",
-	       ret,
-	       (unsigned int) FD_SETSIZE);
-      close (ret);
-      return -1;
-    }
-  return ret;
-}
-
-
-/**
- * Create an ICMP raw socket for writing.
- *
- * @return -1 on error
- */
-static int
-make_raw_socket ()
+setup_raw_socket ()
 {
   const int one = 1;
-  int ret;
 
-  ret = socket (AF_INET, SOCK_RAW, IPPROTO_RAW);
-  if (-1 == ret)
-    {
-      fprintf (stderr,
-	       "Error opening RAW socket: %s\n",
-	       strerror (errno));
-      return -1;
-    }
-  if (-1 == setsockopt(ret,
-		       SOL_SOCKET,
-		       SO_BROADCAST,
-		       (char *)&one, sizeof(one)))
-    {
-      fprintf(stderr,
-	      "setsockopt failed: %s\n",
-	      strerror (errno));
-      close (ret);
-      return -1;
-    }
-  if (-1 == setsockopt(ret,
-		       IPPROTO_IP,
-		       IP_HDRINCL,
-		       (char *)&one, sizeof(one)))
-    {
-      fprintf(stderr,
-	      "setsockopt failed: %s\n",
-	      strerror (errno));
-      close (ret);
-      return -1;
-    }
-  return ret;
+  if (-1 ==
+      setsockopt (rawsock, SOL_SOCKET, SO_BROADCAST, (char *) &one, sizeof (one)))
+  {
+    fprintf (stderr, "setsockopt failed: %s\n", strerror (errno));
+    return -1;
+  }
+  if (-1 ==
+      setsockopt (rawsock, IPPROTO_IP, IP_HDRINCL, (char *) &one, sizeof (one)))
+  {
+    fprintf (stderr, "setsockopt failed: %s\n", strerror (errno));
+    return -1;
+  }
+  return 0;
 }
 
 
 /**
- * Create a UDP socket for writinging.
+ * Create a UDP socket for writing.
  *
  * @param my_ip source address (our ip address)
  * @return -1 on error
@@ -533,15 +455,11 @@ make_udp_socket (const struct in_addr *my_ip)
 
   ret = socket (AF_INET, SOCK_DGRAM, 0);
   if (-1 == ret)
-    {
-      fprintf (stderr,
-	       "Error opening UDP socket: %s\n",
-	       strerror (errno));
-      return -1;
-    }
-  memset (&addr,
-	  0,
-	  sizeof (addr));
+  {
+    fprintf (stderr, "Error opening UDP socket: %s\n", strerror (errno));
+    return -1;
+  }
+  memset (&addr, 0, sizeof (addr));
   addr.sin_family = AF_INET;
 #if HAVE_SOCKADDR_IN_SIN_LEN
   addr.sin_len = sizeof (struct sockaddr_in);
@@ -549,102 +467,150 @@ make_udp_socket (const struct in_addr *my_ip)
   addr.sin_addr = *my_ip;
   addr.sin_port = htons (NAT_TRAV_PORT);
 
-  if (0 != bind (ret,
-		 &addr,
-		 sizeof(addr)))
-    {
-      fprintf (stderr,
-	       "Error binding UDP socket to port %u: %s\n",
-	       NAT_TRAV_PORT,
-	       strerror (errno));
-      /* likely problematic, but not certain, try to continue */
-    }
+  if (0 != bind (ret, &addr, sizeof (addr)))
+  {
+    fprintf (stderr, "Error binding UDP socket to port %u: %s\n", NAT_TRAV_PORT,
+             strerror (errno));
+    (void) close (ret);
+    return -1;
+  }
   return ret;
 }
 
 
 int
-main (int argc,
-      char *const *argv)
+main (int argc, char *const *argv)
 {
   struct in_addr external;
   fd_set rs;
   struct timeval tv;
   uid_t uid;
   unsigned int alt;
+  int icmp_eno;
+  int raw_eno;
+  int global_ret;
+
+  /* Create an ICMP raw socket for reading (we'll check errors later) */
+  icmpsock = socket (AF_INET, SOCK_RAW, IPPROTO_ICMP);
+  icmp_eno = errno;
 
+  /* Create an (ICMP) raw socket for writing (we'll check errors later) */
+  rawsock = socket (AF_INET, SOCK_RAW, IPPROTO_RAW);
+  raw_eno = errno;
+  udpsock = -1;
+
+  /* drop root rights */
+  uid = getuid ();
+#ifdef HAVE_SETRESUID
+  if (0 != setresuid (uid, uid, uid))
+  {
+    fprintf (stderr, "Failed to setresuid: %s\n", strerror (errno));
+    global_ret = 1;
+    goto error_exit;
+  }
+#else
+  if (0 != (setuid (uid) | seteuid (uid)))
+  {
+    fprintf (stderr, "Failed to setuid: %s\n", strerror (errno));
+    global_ret = 2;
+    goto error_exit;
+  }
+#endif
+
+  /* Now that we run without root rights, we can do error checking... */
   if (2 != argc)
-    {
-      fprintf (stderr,
-	       "This program must be started with our (internal NAT) IP as the only argument.\n");
-      return 1;
-    }
+  {
+    fprintf (stderr,
+             "This program must be started with our (internal NAT) IP as the only argument.\n");
+    global_ret = 3;
+    goto error_exit;
+  }
   if (1 != inet_pton (AF_INET, argv[1], &external))
-    {
-      fprintf (stderr,
-              "Error parsing IPv4 address: %s\n",
-              strerror (errno));
-      return 1;
-    }
+  {
+    fprintf (stderr, "Error parsing IPv4 address: %s\n", strerror (errno));
+    global_ret = 4;
+    goto error_exit;
+  }
   if (1 != inet_pton (AF_INET, DUMMY_IP, &dummy))
-    {
-      fprintf (stderr,
-	       "Internal error converting dummy IP to binary.\n");
-      return 2;
-    }
-  if (-1 == (icmpsock = make_icmp_socket()))
-    {
-      return 3;
-    }
-  if (-1 == (rawsock = make_raw_socket()))
-    {
-      close (icmpsock);
-      return 3;
-    }
-  uid = getuid ();
-  if (0 != setresuid (uid, uid, uid))
-    {
-      fprintf (stderr,
-	       "Failed to setresuid: %s\n",
-	       strerror (errno));
-      /* not critical, continue anyway */
-    }
-  if (-1 == (udpsock = make_udp_socket(&external)))
-    {
-      close (icmpsock);
-      close (rawsock);
-      return 3;
-    }
+  {
+    fprintf (stderr, "Internal error converting dummy IP to binary.\n");
+    global_ret = 5;
+    goto error_exit;
+  }
+
+  /* error checking icmpsock */
+  if (-1 == icmpsock)
+  {
+    fprintf (stderr, "Error opening RAW socket: %s\n", strerror (icmp_eno));
+    global_ret = 6;
+    goto error_exit;
+  }
+  if (icmpsock >= FD_SETSIZE)
+  {
+    /* this could happen if we were started with a large number of already-open
+       file descriptors... */
+    fprintf (stderr, "Socket number too large (%d > %u)\n", icmpsock,
+             (unsigned int) FD_SETSIZE);
+    global_ret = 7;
+    goto error_exit;
+  }
+
+  /* error checking rawsock */
+  if (-1 == rawsock)
+  {
+    fprintf (stderr, "Error opening RAW socket: %s\n", strerror (raw_eno));
+    global_ret = 8;
+    goto error_exit;
+  }
+  /* no need to check 'rawsock' against FD_SETSIZE as it is never used
+     with 'select' */
+
+  if (0 != setup_raw_socket ())
+  {
+    global_ret = 9;
+    goto error_exit;
+  }
+
+  if (-1 == (udpsock = make_udp_socket (&external)))
+  {
+    global_ret = 10;
+    goto error_exit;
+  }
+
   alt = 0;
   while (1)
+  {
+    FD_ZERO (&rs);
+    FD_SET (icmpsock, &rs);
+    tv.tv_sec = 0;
+    tv.tv_usec = ICMP_SEND_FREQUENCY_MS * 1000;
+    if (-1 == select (icmpsock + 1, &rs, NULL, NULL, &tv))
     {
-      FD_ZERO (&rs);
-      FD_SET (icmpsock, &rs);
-      tv.tv_sec = 0;
-      tv.tv_usec = ICMP_SEND_FREQUENCY_MS * 1000;
-      if (-1 == select (icmpsock + 1, &rs, NULL, NULL, &tv))
-	{
-	  if (errno == EINTR)
-	    continue;
-	  fprintf (stderr,
-		   "select failed: %s\n",
-		   strerror (errno));
-	  break;
-	}
-      if (1 == getppid()) /* Check the parent process id, if 1 the parent has died, so we should die too */
-        break;
-      if (FD_ISSET (icmpsock, &rs))
-        process_icmp_response ();
-      if (0 == (++alt % 2))
-	send_icmp_echo (&external);
-      else
-	send_udp ();
+      if (errno == EINTR)
+        continue;
+      fprintf (stderr, "select failed: %s\n", strerror (errno));
+      break;
     }
+    if (1 == getppid ())        /* Check the parent process id, if 1 the parent has died, so we should die too */
+      break;
+    if (FD_ISSET (icmpsock, &rs))
+      process_icmp_response ();
+    if (0 == (++alt % 2))
+      send_icmp_echo (&external);
+    else
+      send_udp ();
+  }
+
   /* select failed (internal error or OS out of resources) */
-  close (icmpsock);
-  close (rawsock);
-  close (udpsock);
-  return 4;
+  global_ret = 11; 
+error_exit:
+  if (-1 != icmpsock)
+    (void) close (icmpsock);
+  if (-1 != rawsock)
+    (void) close (rawsock);
+  if (-1 != udpsock)
+    (void) close (udpsock);
+  return global_ret;
 }