/**
* @file src/transport/gnunet-nat-client.c
* @brief Tool to help bypass NATs using ICMP method; must run as root (SUID will do)
- * This code will work under GNU/Linux only.
+ * This code will work under GNU/Linux only.
* @author Christian Grothoff
*
* This program will send ONE ICMP message using RAW sockets
*
* - Christian Grothoff
* - Nathan Evans
+ * - Benjamin Kuperman (22 Aug 2010)
*/
#if HAVE_CONFIG_H
/* Just needed for HAVE_SOCKADDR_IN_SIN_LEN test macro! */
#else
#define _GNU_SOURCE
#endif
-#include <sys/types.h>
+#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <stdint.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
-#include <netinet/in.h>
+#include <netinet/in.h>
/**
* Must match IP given in the server.
/**
* IPv4 header.
*/
-struct ip_header
+struct ip_header
{
/**
- * Version (4 bits) + Internet header length (4 bits)
+ * Version (4 bits) + Internet header length (4 bits)
*/
uint8_t vers_ihl;
uint8_t ttl;
/**
- * Protocol
+ * Protocol
*/
uint8_t proto;
-
+
/**
* Header checksum
*/
uint32_t src_ip;
/**
- * Destination address
+ * Destination address
*/
uint32_t dst_ip;
};
/**
* Format of ICMP packet.
*/
-struct icmp_ttl_exceeded_header
+struct icmp_ttl_exceeded_header
{
uint8_t type;
uint16_t dst_port;
uint16_t length;
-
+
uint16_t crc;
};
* Target "dummy" address of the packet we pretend to respond to.
*/
static struct in_addr dummy;
-
+
/**
* Our "source" port.
*/
* @param bytes number of bytes in data (must be multiple of 2)
* @return the CRC 16.
*/
-static uint16_t
-calc_checksum (const uint16_t *data,
+static uint16_t
+calc_checksum (const uint16_t *data,
unsigned int bytes)
{
uint32_t sum;
unsigned int i;
sum = 0;
- for (i=0;i<bytes/2;i++)
- sum += data[i];
+ for (i=0;i<bytes/2;i++)
+ sum += data[i];
sum = (sum & 0xffff) + (sum >> 16);
sum = htons(0xffff - sum);
return sum;
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) +
+ 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;
off = 0;
ip_pkt.vers_ihl = 0x45;
ip_pkt.tos = 0;
- ip_pkt.pkt_len = htons(sizeof (packet));
+ ip_pkt.pkt_len = htons (sizeof (packet));
ip_pkt.id = htons(256);
ip_pkt.flags_frag_offset = 0;
ip_pkt.ttl = 128;
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,
+ ip_pkt.checksum = htons(calc_checksum((uint16_t*)&ip_pkt,
sizeof (struct ip_header)));
- memcpy(&packet[off],
- &ip_pkt,
+ memcpy(&packet[off],
+ &ip_pkt,
sizeof(struct ip_header));
off += sizeof(struct ip_header);
icmp_pkt.checksum = 0;
icmp_pkt.unused = 0;
memcpy(&packet[off],
- &icmp_pkt,
+ &icmp_pkt,
sizeof(struct icmp_ttl_exceeded_header));
off += sizeof(struct icmp_ttl_exceeded_header);
ip_pkt.vers_ihl = 0x45;
ip_pkt.tos = 0;
ip_pkt.pkt_len = htons(sizeof (struct ip_header) +
- sizeof(struct udp_header));
+ sizeof (struct udp_header));
ip_pkt.id = htons(0);
ip_pkt.flags_frag_offset = 0;
ip_pkt.ttl = 128;
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,
+ 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.length = htons (sizeof (struct udp_header));
- udp_pkt.crc = htons (port);
- memcpy(&packet[off],
+ udp_pkt.length = htons (port);
+ udp_pkt.crc = 0;
+ memcpy(&packet[off],
&udp_pkt,
sizeof(struct udp_header));
off += sizeof(struct udp_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));
+ 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_addr = *other;
err = sendto(rawsock,
packet,
- off, 0,
+ sizeof (packet), 0,
(struct sockaddr*)&dst,
sizeof(dst));
if (err < 0)
fprintf(stderr,
"sendto failed: %s\n", strerror(errno));
}
- else if (off != (size_t) err)
+ else if (sizeof (packet) != (size_t) err)
{
fprintf(stderr,
"Error: partial send of ICMP message\n");
const struct in_addr *other)
{
struct ip_header ip_pkt;
- struct icmp_ttl_exceeded_header icmp_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 +
off = 0;
ip_pkt.vers_ihl = 0x45;
ip_pkt.tos = 0;
- ip_pkt.pkt_len = sizeof (packet);
- ip_pkt.id = 1;
+ ip_pkt.pkt_len = htons (sizeof (packet));
+ ip_pkt.id = htons (256);
ip_pkt.flags_frag_offset = 0;
ip_pkt.ttl = IPDEFTTL;
ip_pkt.proto = IPPROTO_ICMP;
- ip_pkt.checksum = 0;
+ 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,
+ ip_pkt.checksum = htons(calc_checksum((uint16_t*)&ip_pkt,
sizeof (struct ip_header)));
- memcpy (&packet[off],
- &ip_pkt,
+ memcpy (&packet[off],
+ &ip_pkt,
sizeof (struct ip_header));
off = sizeof (ip_pkt);
/* icmp reply: time exceeded */
- icmp_pkt.type = ICMP_TIME_EXCEEDED;
- icmp_pkt.code = 0;
- icmp_pkt.checksum = 0;
- icmp_pkt.unused = 0;
+ icmp_ttl.type = ICMP_TIME_EXCEEDED;
+ icmp_ttl.code = 0;
+ icmp_ttl.checksum = 0;
+ icmp_ttl.unused = 0;
memcpy (&packet[off],
- &icmp_pkt,
+ &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 = (sizeof (struct ip_header) + sizeof (struct icmp_echo_header));
- ip_pkt.id = 1;
+ ip_pkt.pkt_len = htons (sizeof (struct ip_header) + sizeof (struct icmp_echo_header));
+ ip_pkt.id = htons (256);
ip_pkt.flags_frag_offset = 0;
ip_pkt.ttl = 1; /* real TTL would be 1 on a time exceeded packet */
ip_pkt.proto = IPPROTO_ICMP;
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)));
+ memcpy (&packet[off],
+ &ip_pkt,
sizeof (struct ip_header));
off += sizeof (struct ip_header);
icmp_echo.code = 0;
icmp_echo.reserved = htonl (port);
icmp_echo.checksum = 0;
- icmp_echo.checksum = htons(calc_checksum((uint16_t*) &icmp_echo,
+ icmp_echo.checksum = htons(calc_checksum((uint16_t*) &icmp_echo,
sizeof (struct icmp_echo_header)));
- memcpy (&packet[off],
+ memcpy (&packet[off],
&icmp_echo,
sizeof(struct icmp_echo_header));
/* no go back to calculate ICMP packet checksum */
off = sizeof (struct ip_header);
- icmp_pkt.checksum = htons(calc_checksum((uint16_t*) &packet[off],
- sizeof (struct icmp_ttl_exceeded_header) +
- sizeof(struct ip_header) +
- sizeof(struct icmp_echo_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_pkt,
+ &icmp_ttl,
sizeof (struct icmp_ttl_exceeded_header));
/* prepare for transmission */
dst.sin_len = sizeof (struct sockaddr_in);
#endif
dst.sin_addr = *other;
- err = sendto(rawsock,
- packet,
- sizeof (packet), 0,
- (struct sockaddr*)&dst,
- sizeof(struct sockaddr_in));
- if (err < 0)
+ 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)
+ else if (sizeof (packet) != (size_t) err)
{
fprintf(stderr,
"Error: partial send of ICMP message\n");
"Error opening RAW socket: %s\n",
strerror (errno));
return -1;
- }
- if (-1 == setsockopt(ret, SOL_SOCKET, SO_BROADCAST,
- (char *)&one, sizeof(one)))
+ }
+ if (0 != setsockopt(ret, SOL_SOCKET, SO_BROADCAST,
+ (char *)&one, sizeof(one)))
{
fprintf(stderr,
"setsockopt failed: %s\n",
close (ret);
return -1;
}
- if (-1 == setsockopt(ret, IPPROTO_IP, IP_HDRINCL,
- (char *)&one, sizeof(one)))
+ if (0 != setsockopt(ret, IPPROTO_IP, IP_HDRINCL,
+ (char *)&one, sizeof(one)))
{
fprintf(stderr,
"setsockopt failed: %s\n",
return 1;
}
port = (uint16_t) p;
- if (1 != inet_pton (AF_INET, DUMMY_IP, &dummy))
+ 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;
+ return 2;
uid = getuid ();
if (0 != setresuid (uid, uid, uid))
{