/*
This file is part of GNUnet.
- (C) 2010 Christian Grothoff (and other contributing authors)
+ Copyright (C) 2010 Christian Grothoff (and other contributing authors)
GNUnet is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
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.
+ Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ Boston, MA 02110-1301, USA.
*/
/**
* - 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! */
#include <netinet/ip_icmp.h>
#include <netinet/in.h>
+/* The following constant is missing from FreeBSD 9.2 */
+#ifndef ICMP_TIME_EXCEEDED
+#define ICMP_TIME_EXCEEDED 11
+#endif
+
/**
* Should we print some debug output?
*/
#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.
*/
* @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;
}
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));
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");
+ }
}
#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");
+ }
}
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;
+ }
+ /* grab source IP of 1st IP header */
+ source_ip.s_addr = ip_pkt.src_ip;
+
/* 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;
+ }
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
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);
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 */
- }
+ (struct sockaddr *) &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;
}
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