/*
This file is part of GNUnet.
- (C) 2010 Christian Grothoff (and other contributing authors)
+ Copyright (C) 2010 GNUnet e.V.
- 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 free software: you can redistribute it and/or modify it
+ under the terms of the GNU Affero General Public License as published
+ by the Free Software Foundation, either version 3 of the License,
+ 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.
+ Affero 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.
-*/
+ You should have received a copy of the GNU Affero General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+ SPDX-License-Identifier: AGPL3.0-or-later
+ */
/**
* @file src/nat/gnunet-helper-nat-client.c
#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
+
+/**
+ * Call memcpy() but check for @a n being 0 first. In the latter
+ * case, it is now safe to pass NULL for @a src or @a dst.
+ * Unlike traditional memcpy(), returns nothing.
+ *
+ * @param dst destination of the copy, may be NULL if @a n is zero
+ * @param src source of the copy, may be NULL if @a n is zero
+ * @param n number of bytes to copy
+ */
+#define GNUNET_memcpy(dst, src, n) do { if (0 != n) { (void) memcpy (dst, src, \
+ n); \
+ } } while (0)
+
/**
* Must match IP given in the server.
*/
#define NAT_TRAV_PORT 22225
+/**
+ * Must match packet ID used by gnunet-helper-nat-server.c
+ */
+#define PACKET_ID 256
+
/**
* IPv4 header.
*/
struct ip_header
{
-
/**
* Version (4 bits) + Internet header length (4 bits)
*/
* @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;
}
* @param other target address
*/
static void
-send_icmp_udp (const struct in_addr *my_ip,
- const struct in_addr *other)
+send_icmp_udp (const struct in_addr *my_ip, const struct in_addr *other)
{
- char packet[sizeof(struct ip_header) * 2 +
- sizeof(struct icmp_ttl_exceeded_header) +
- sizeof(struct udp_header)];
+ char packet[sizeof(struct ip_header) * 2
+ + sizeof(struct icmp_ttl_exceeded_header)
+ + sizeof(struct udp_header)];
struct ip_header ip_pkt;
struct icmp_ttl_exceeded_header icmp_pkt;
struct udp_header udp_pkt;
off = 0;
ip_pkt.vers_ihl = 0x45;
ip_pkt.tos = 0;
- ip_pkt.pkt_len = htons (sizeof (packet));
- ip_pkt.id = htons(256);
+#ifdef FREEBSD
+ ip_pkt.pkt_len = sizeof(packet); /* Workaround PR kern/21737 */
+#else
+ ip_pkt.pkt_len = htons (sizeof(packet));
+#endif
+ ip_pkt.id = htons (PACKET_ID);
ip_pkt.flags_frag_offset = 0;
ip_pkt.ttl = 128;
ip_pkt.proto = IPPROTO_ICMP;
ip_pkt.checksum = 0;
ip_pkt.src_ip = my_ip->s_addr;
ip_pkt.dst_ip = other->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)));
+ GNUNET_memcpy (&packet[off],
+ &ip_pkt,
+ sizeof(struct ip_header));
off += sizeof(struct ip_header);
icmp_pkt.type = ICMP_TIME_EXCEEDED;
icmp_pkt.code = 0;
icmp_pkt.checksum = 0;
icmp_pkt.unused = 0;
- memcpy(&packet[off],
- &icmp_pkt,
- sizeof(struct icmp_ttl_exceeded_header));
+ GNUNET_memcpy (&packet[off],
+ &icmp_pkt,
+ sizeof(struct icmp_ttl_exceeded_header));
off += sizeof(struct icmp_ttl_exceeded_header);
/* ip header of the presumably 'lost' udp packet */
ip_pkt.vers_ihl = 0x45;
ip_pkt.tos = 0;
- ip_pkt.pkt_len = htons(sizeof (struct ip_header) +
- sizeof (struct udp_header));
- ip_pkt.id = htons(0);
+ ip_pkt.pkt_len =
+ htons (sizeof(struct ip_header) + sizeof(struct udp_header));
+ ip_pkt.id = htons (0);
ip_pkt.flags_frag_offset = 0;
ip_pkt.ttl = 128;
ip_pkt.proto = IPPROTO_UDP;
ip_pkt.checksum = 0;
ip_pkt.src_ip = other->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)));
+ GNUNET_memcpy (&packet[off],
+ &ip_pkt,
+ sizeof(struct ip_header));
off += sizeof(struct ip_header);
/* build UDP header */
- udp_pkt.src_port = htons(NAT_TRAV_PORT);
- udp_pkt.dst_port = htons(NAT_TRAV_PORT);
+ udp_pkt.src_port = htons (NAT_TRAV_PORT);
+ udp_pkt.dst_port = htons (NAT_TRAV_PORT);
udp_pkt.length = htons (port);
udp_pkt.crc = 0;
- memcpy(&packet[off],
- &udp_pkt,
- sizeof(struct udp_header));
+ GNUNET_memcpy (&packet[off],
+ &udp_pkt,
+ sizeof(struct udp_header));
off += sizeof(struct udp_header);
/* set ICMP checksum */
- icmp_pkt.checksum = htons(calc_checksum((uint16_t*)&packet[sizeof(struct ip_header)],
- sizeof (struct icmp_ttl_exceeded_header) +
- sizeof (struct ip_header) +
- sizeof (struct udp_header)));
- memcpy (&packet[sizeof(struct ip_header)],
- &icmp_pkt,
- sizeof (struct icmp_ttl_exceeded_header));
-
- memset (&dst, 0, sizeof (dst));
+ icmp_pkt.checksum =
+ htons (calc_checksum
+ ((uint16_t *) &packet[sizeof(struct ip_header)],
+ sizeof(struct icmp_ttl_exceeded_header)
+ + sizeof(struct ip_header) + sizeof(struct udp_header)));
+ GNUNET_memcpy (&packet[sizeof(struct ip_header)],
+ &icmp_pkt,
+ sizeof(struct icmp_ttl_exceeded_header));
+
+ memset (&dst, 0, sizeof(dst));
dst.sin_family = AF_INET;
#if HAVE_SOCKADDR_IN_SIN_LEN
- dst.sin_len = sizeof (struct sockaddr_in);
+ dst.sin_len = sizeof(struct sockaddr_in);
#endif
dst.sin_addr = *other;
- err = sendto(rawsock,
- packet,
- sizeof (packet), 0,
- (struct sockaddr*)&dst,
- sizeof(dst));
+ err =
+ sendto (rawsock, packet, sizeof(packet), 0, (struct sockaddr *) &dst,
+ sizeof(dst));
if (err < 0)
- {
- fprintf(stderr,
- "sendto failed: %s\n", strerror(errno));
- }
- else if (sizeof (packet) != (size_t) err)
- {
- fprintf(stderr,
- "Error: partial send of ICMP message\n");
- }
+ {
+ fprintf (stderr, "sendto failed: %s\n", strerror (errno));
+ }
+ else if (sizeof(packet) != (size_t) err)
+ {
+ fprintf (stderr, "Error: partial send of ICMP message with size %lu\n",
+ (unsigned long) off);
+ }
}
* @param other target address
*/
static void
-send_icmp (const struct in_addr *my_ip,
- const struct in_addr *other)
+send_icmp (const struct in_addr *my_ip, const struct in_addr *other)
{
struct ip_header ip_pkt;
struct icmp_ttl_exceeded_header icmp_ttl;
struct icmp_echo_header icmp_echo;
struct sockaddr_in dst;
- char packet[sizeof (struct ip_header) * 2 +
- sizeof (struct icmp_ttl_exceeded_header) +
- sizeof (struct icmp_echo_header)];
+ char packet[sizeof(struct ip_header) * 2
+ + sizeof(struct icmp_ttl_exceeded_header)
+ + sizeof(struct icmp_echo_header)];
size_t off;
int err;
off = 0;
ip_pkt.vers_ihl = 0x45;
ip_pkt.tos = 0;
- ip_pkt.pkt_len = htons (sizeof (packet));
- ip_pkt.id = htons (256);
+#ifdef FREEBSD
+ ip_pkt.pkt_len = sizeof(packet); /* Workaround PR kern/21737 */
+#else
+ ip_pkt.pkt_len = htons (sizeof(packet));
+#endif
+ 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 = other->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));
- off = sizeof (ip_pkt);
+ ip_pkt.checksum =
+ htons (calc_checksum ((uint16_t *) &ip_pkt, sizeof(struct ip_header)));
+ GNUNET_memcpy (&packet[off],
+ &ip_pkt,
+ sizeof(struct ip_header));
+ off = sizeof(ip_pkt);
/* icmp reply: time exceeded */
icmp_ttl.type = ICMP_TIME_EXCEEDED;
icmp_ttl.code = 0;
icmp_ttl.checksum = 0;
icmp_ttl.unused = 0;
- memcpy (&packet[off],
- &icmp_ttl,
- sizeof (struct icmp_ttl_exceeded_header));
- off += sizeof (struct icmp_ttl_exceeded_header);
+ GNUNET_memcpy (&packet[off],
+ &icmp_ttl,
+ sizeof(struct icmp_ttl_exceeded_header));
+ off += sizeof(struct icmp_ttl_exceeded_header);
/* ip header of the presumably 'lost' udp packet */
ip_pkt.vers_ihl = 0x45;
ip_pkt.tos = 0;
- ip_pkt.pkt_len = htons (sizeof (struct ip_header) + sizeof (struct icmp_echo_header));
- ip_pkt.id = htons (256);
+ ip_pkt.pkt_len =
+ htons (sizeof(struct ip_header) + sizeof(struct icmp_echo_header));
+ ip_pkt.id = htons (PACKET_ID);
ip_pkt.flags_frag_offset = 0;
- ip_pkt.ttl = 1; /* real TTL would be 1 on a time exceeded packet */
+ ip_pkt.ttl = 1; /* real TTL would be 1 on a time exceeded packet */
ip_pkt.proto = IPPROTO_ICMP;
ip_pkt.src_ip = other->s_addr;
ip_pkt.dst_ip = dummy.s_addr;
ip_pkt.checksum = 0;
- 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);
+ ip_pkt.checksum =
+ htons (calc_checksum ((uint16_t *) &ip_pkt, sizeof(struct ip_header)));
+ GNUNET_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.reserved = htonl (port);
icmp_echo.checksum = 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)));
+ GNUNET_memcpy (&packet[off],
+ &icmp_echo,
+ sizeof(struct icmp_echo_header));
/* no go back to calculate ICMP packet checksum */
- off = sizeof (struct ip_header);
- icmp_ttl.checksum = htons(calc_checksum((uint16_t*) &packet[off],
- sizeof (struct icmp_ttl_exceeded_header) +
- sizeof (struct ip_header) +
- sizeof (struct icmp_echo_header)));
- memcpy (&packet[off],
- &icmp_ttl,
- sizeof (struct icmp_ttl_exceeded_header));
+ off = sizeof(struct ip_header);
+ icmp_ttl.checksum =
+ htons (calc_checksum
+ ((uint16_t *) &packet[off],
+ sizeof(struct icmp_ttl_exceeded_header)
+ + sizeof(struct ip_header) + sizeof(struct icmp_echo_header)));
+ GNUNET_memcpy (&packet[off],
+ &icmp_ttl,
+ sizeof(struct icmp_ttl_exceeded_header));
/* prepare for transmission */
- memset (&dst, 0, sizeof (dst));
+ memset (&dst, 0, sizeof(dst));
dst.sin_family = AF_INET;
#if HAVE_SOCKADDR_IN_SIN_LEN
- dst.sin_len = sizeof (struct sockaddr_in);
+ dst.sin_len = sizeof(struct sockaddr_in);
#endif
dst.sin_addr = *other;
- err = sendto(rawsock,
- packet,
- sizeof (packet), 0,
- (struct sockaddr*)&dst,
- sizeof(dst));
+ err =
+ sendto (rawsock, packet, sizeof(packet), 0, (struct sockaddr *) &dst,
+ sizeof(dst));
if (err < 0)
- {
- fprintf(stderr,
- "sendto failed: %s\n", strerror(errno));
- }
- else if (sizeof (packet) != (size_t) err)
- {
- fprintf(stderr,
- "Error: partial send of ICMP message\n");
- }
-}
-
-
-/**
- * Create an ICMP raw socket for writing.
- *
- * @return -1 on error
- */
-static int
-make_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 (0 != setsockopt(ret, SOL_SOCKET, SO_BROADCAST,
- (char *)&one, sizeof(one)))
- {
- fprintf(stderr,
- "setsockopt failed: %s\n",
- strerror (errno));
- close (ret);
- return -1;
- }
- if (0 != setsockopt(ret, IPPROTO_IP, IP_HDRINCL,
- (char *)&one, sizeof(one)))
- {
- fprintf(stderr,
- "setsockopt failed: %s\n",
- strerror (errno));
- close (ret);
- return -1;
- }
- return ret;
+ {
+ fprintf (stderr, "sendto failed: %s\n", strerror (errno));
+ }
+ else if (sizeof(packet) != (size_t) err)
+ {
+ fprintf (stderr, "Error: partial send of ICMP message\n");
+ }
}
int
main (int argc, char *const *argv)
{
+ const int one = 1;
struct in_addr external;
struct in_addr target;
uid_t uid;
unsigned int p;
+ int raw_eno;
+ int global_ret;
+
+ /* Create an ICMP raw socket for writing (only operation that requires root) */
+ rawsock = socket (AF_INET, SOCK_RAW, IPPROTO_RAW);
+ raw_eno = errno; /* for later error checking */
+
+ /* now drop root privileges */
+ uid = getuid ();
+#ifdef HAVE_SETRESUID
+ if (0 != setresuid (uid, uid, uid))
+ {
+ fprintf (stderr, "Failed to setresuid: %s\n", strerror (errno));
+ global_ret = 1;
+ 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 (-1 == rawsock)
+ {
+ fprintf (stderr, "Error opening RAW socket: %s\n", strerror (raw_eno));
+ global_ret = 3;
+ goto cleanup;
+ }
+ if (0 !=
+ setsockopt (rawsock, SOL_SOCKET, SO_BROADCAST, (char *) &one,
+ sizeof(one)))
+ {
+ fprintf (stderr, "setsockopt failed: %s\n", strerror (errno));
+ global_ret = 4;
+ goto cleanup;
+ }
+ if (0 !=
+ setsockopt (rawsock, IPPROTO_IP, IP_HDRINCL, (char *) &one, sizeof(one)))
+ {
+ fprintf (stderr, "setsockopt failed: %s\n", strerror (errno));
+ global_ret = 5;
+ goto cleanup;
+ }
if (4 != argc)
- {
- fprintf (stderr,
- "This program must be started with our IP, the targets external IP, and our port as arguments.\n");
- return 1;
- }
- if ( (1 != inet_pton (AF_INET, argv[1], &external)) ||
- (1 != inet_pton (AF_INET, argv[2], &target)) )
- {
- fprintf (stderr,
- "Error parsing IPv4 address: %s\n",
- strerror (errno));
- return 1;
- }
- if ( (1 != sscanf (argv[3], "%u", &p) ) ||
- (0 == p) ||
- (0xFFFF < p) )
- {
- fprintf (stderr,
- "Error parsing port value `%s'\n",
- argv[3]);
- return 1;
- }
+ {
+ fprintf (stderr,
+ "This program must be started with our IP, the targets external IP, and our port as arguments.\n");
+ global_ret = 6;
+ goto cleanup;
+ }
+ if ((1 != inet_pton (AF_INET, argv[1], &external)) ||
+ (1 != inet_pton (AF_INET, argv[2], &target)))
+ {
+ fprintf (stderr, "Error parsing IPv4 address: %s\n", strerror (errno));
+ global_ret = 7;
+ goto cleanup;
+ }
+ if ((1 != sscanf (argv[3], "%u", &p)) || (0 == p) || (0xFFFF < p))
+ {
+ fprintf (stderr, "Error parsing port value `%s'\n", argv[3]);
+ global_ret = 8;
+ goto cleanup;
+ }
port = (uint16_t) p;
if (1 != inet_pton (AF_INET, DUMMY_IP, &dummy))
- {
- fprintf (stderr,
- "Internal error converting dummy IP to binary.\n");
- return 2;
- }
- if (-1 == (rawsock = make_raw_socket()))
- return 2;
- uid = getuid ();
- if (0 != setresuid (uid, uid, uid))
- {
- fprintf (stderr,
- "Failed to setresuid: %s\n",
- strerror (errno));
- /* not critical, continue anyway */
- }
- send_icmp (&external,
- &target);
- send_icmp_udp (&external,
- &target);
- close (rawsock);
- return 0;
+ {
+ fprintf (stderr, "Internal error converting dummy IP to binary.\n");
+ global_ret = 9;
+ goto cleanup;
+ }
+ send_icmp (&external, &target);
+ send_icmp_udp (&external, &target);
+ global_ret = 0;
+cleanup:
+ if (-1 != rawsock)
+ (void) close (rawsock);
+ return global_ret;
}
+
/* end of gnunet-helper-nat-client.c */
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