/**
* @file src/transport/gnunet-nat-server.c
- * @brief Tool to help bypass NATs using ICMP method; must run as root (for now, later SUID will do)
+ * @brief Tool to help bypass NATs using ICMP method; must run as root (SUID will do)
* This code will work under GNU/Linux only (or maybe BSDs, but never W32)
* @author Christian Grothoff
+ *
+ * This program will send ONE ICMP message every 500 ms RAW sockets
+ * to a DUMMY IP address and also listens for ICMP replies. Since
+ * it uses RAW sockets, it must be installed SUID or run as 'root'.
+ * In order to keep the security risk of the resulting SUID binary
+ * minimal, the program ONLY opens the two RAW sockets with root
+ * privileges, then drops them and only then starts to process
+ * command line arguments. The code also does not link against
+ * any shared libraries (except libc) and is strictly minimal
+ * (except for checking for errors). 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):
+ *
+ * - Christian Grothoff
+ * - Nathan Evans
+ * - Benjamin Kuperman (22 Aug 2010)
*/
-
-#include <sys/types.h>
+#if HAVE_CONFIG_H
+/* Just needed for HAVE_SOCKADDR_IN_SIN_LEN test macro! */
+#include "gnunet_config.h"
+#else
+#define _GNU_SOURCE
+#endif
+#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/select.h>
#include <time.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
-#include <netinet/in.h>
-
-#define DEBUG 0
+#include <netinet/in.h>
/**
- * Number of UDP ports to keep open (typically >= 256).
+ * Should we print some debug output?
*/
-#define NUM_UDP_PORTS 256
+#define VERBOSE 0
/**
- * Number of ICMP replies to send per message received (typically >= 1024)
+ * Must match IP given in the client.
*/
-#define NUM_ICMP_REPLIES 1024
+#define DUMMY_IP "192.0.2.86"
/**
- * How often do we send our UDP messages to keep ports open? (typically < 100ms)
+ * Port for UDP
*/
-#define UDP_SEND_FREQUENCY_MS 50
+#define NAT_TRAV_PORT 22225
/**
- * Port we use for the dummy target.
+ * How often do we send our ICMP messages to receive replies?
*/
-#define NAT_TRAV_PORT 2222
+#define ICMP_SEND_FREQUENCY_MS 500
/**
- * How often do we retry to open and bind a UDP socket before giving up?
+ * IPv4 header.
*/
-#define MAX_TRIES 10
-
-
-struct ip_packet
+struct ip_header
{
+ /**
+ * Version (4 bits) + Internet header length (4 bits)
+ */
uint8_t vers_ihl;
+
+ /**
+ * Type of service
+ */
uint8_t tos;
+
+ /**
+ * Total length
+ */
uint16_t pkt_len;
+
+ /**
+ * Identification
+ */
uint16_t id;
+
+ /**
+ * Flags (3 bits) + Fragment offset (13 bits)
+ */
uint16_t flags_frag_offset;
+
+ /**
+ * Time to live
+ */
uint8_t ttl;
+
+ /**
+ * Protocol
+ */
uint8_t proto;
+
+ /**
+ * Header checksum
+ */
uint16_t checksum;
+
+ /**
+ * Source address
+ */
uint32_t src_ip;
+
+ /**
+ * Destination address
+ */
uint32_t dst_ip;
};
-
-struct udp_packet
+/**
+ * Format of ICMP packet.
+ */
+struct icmp_ttl_exceeded_header
{
- uint16_t source_port;
- uint16_t dst_port;
- uint16_t mlen_aka_reply_port_magic;
- uint16_t checksum_aka_my_magic;
-};
+ uint8_t type;
+
+ uint8_t code;
+
+ uint16_t checksum;
+ uint32_t unused;
-struct icmp_packet
+ /* followed by original payload */
+};
+
+struct icmp_echo_header
{
uint8_t type;
+
uint8_t code;
+
uint16_t checksum;
+
uint32_t reserved;
- struct ip_packet ip;
- struct udp_packet udp;
};
/**
- * Structure of the data we tack on to the fake ICMP reply
- * (last 4 bytes of the 64 bytes).
+ * Beginning of UDP packet.
*/
-struct extra_packet
+struct udp_header
{
- /**
- * if this is a reply to an icmp, what was the 'my_magic'
- * value from the original icmp?
- */
- uint16_t reply_port_magic;
+ uint16_t src_port;
- /**
- * magic value of the sender of this icmp message.
- */
- uint16_t my_magic;
-};
+ uint16_t dst_port;
+
+ uint16_t length;
-static int udpsocks[NUM_UDP_PORTS];
+ uint16_t crc;
+};
-static uint16_t udpports[NUM_UDP_PORTS];
-
+/**
+ * Socket we use to receive "fake" ICMP replies.
+ */
static int icmpsock;
+/**
+ * Socket we use to send our ICMP requests.
+ */
static int rawsock;
-static struct in_addr dummy;
-
-
/**
- * create a random port number that is not totally
- * unlikely to be chosen by the nat box.
- */
-static uint16_t make_port ()
-{
- return 1024 + ( (unsigned int)rand ()) % (63 * 1024 - 2);
-}
-
+ * Socket we use to send our UDP requests.
+ */
+static int udpsock;
/**
- * create a fresh udp socket bound to a random local port.
+ * Target "dummy" address.
*/
-static int
-make_udp_socket (uint16_t *port)
-{
- int ret;
- int tries;
- struct sockaddr_in src;
-
- for (tries=0;tries<MAX_TRIES;tries++)
- {
- ret = socket (AF_INET, SOCK_DGRAM, 0);
- if (-1 == ret)
- {
- fprintf (stderr,
- "Error opening udp 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;
- }
- memset (&src, 0, sizeof (src));
- src.sin_family = AF_INET;
- src.sin_port = htons (make_port ());
- if (0 != bind (ret, (struct sockaddr*) &src, sizeof (src)))
- {
- close (ret);
- continue;
- }
- *port = ntohs (src.sin_port);
- return ret;
- }
- fprintf (stderr,
- "Error binding udp socket: %s\n",
- strerror (errno));
- return -1;
-}
+static struct in_addr dummy;
-static uint16_t
-calc_checksum(const uint16_t *data,
+/**
+ * CRC-16 for IP/ICMP headers.
+ *
+ * @param data what to calculate the CRC over
+ * @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,
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 an icmp message to the target.
+ * Send an ICMP message to the dummy IP.
*
* @param my_ip source address (our ip address)
- * @param other target address
- * @param target_port_number fake port number to put into icmp response
- * as well as the icmpextradata as 'my_magic'
- * @param source_port_number magic_number that enables the other peer to
- * identify our port number ('reply in response to') to
- * put in the data portion; 0 if we are initiating;
- * goes into 'reply_port_magic' of the icmpextradata
*/
static void
-send_icmp (const struct in_addr *my_ip,
- const struct in_addr *other,
- uint16_t target_port_number,
- uint16_t source_port_number)
+send_icmp_echo (const struct in_addr *my_ip)
{
- struct ip_packet ip_pkt;
- struct icmp_packet icmp_pkt;
+ char packet[sizeof (struct ip_header) + sizeof (struct icmp_echo_header)];
+ struct icmp_echo_header icmp_echo;
+ struct ip_header ip_pkt;
struct sockaddr_in dst;
- char packet[sizeof (ip_pkt) + sizeof (icmp_pkt)];
size_t off;
int err;
- /* ip header: send to (known) ip address */
off = 0;
- memset(&ip_pkt, 0, sizeof(ip_pkt));
- ip_pkt.vers_ihl = 0x45;//|(pkt_len>>2);//5;//(ipversion << 4) | (iphdr_size >> 2);
+ ip_pkt.vers_ihl = 0x45;
ip_pkt.tos = 0;
- ip_pkt.pkt_len = sizeof (packet); /* huh? */
- ip_pkt.id = 1; /* kernel will change anyway!? */
+ 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; /* maybe the kernel helps us out..? */
+ 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 (ip_pkt)));
- memcpy (packet, &ip_pkt, sizeof (ip_pkt));
- off += sizeof (ip_pkt);
-
- /* icmp reply: time exceeded */
- memset(&icmp_pkt, 0, sizeof(icmp_pkt));
- icmp_pkt.type = ICMP_TIME_EXCEEDED;
- icmp_pkt.code = ICMP_NET_UNREACH;
- icmp_pkt.reserved = 0;
- icmp_pkt.checksum = 0;
-
- /* ip header of the presumably 'lost' udp packet */
- icmp_pkt.ip.vers_ihl = 0x45;
- icmp_pkt.ip.tos = 0;
- /* no idea why i need to shift the bits here, but not on ip_pkt->pkt_len... */
- icmp_pkt.ip.pkt_len = (sizeof (ip_pkt) + sizeof (icmp_pkt)) << 8;
- icmp_pkt.ip.id = 1; /* kernel sets proper value htons(ip_id_counter); */
- icmp_pkt.ip.flags_frag_offset = 0;
- icmp_pkt.ip.ttl = 1; /* real TTL would be 1 on a time exceeded packet */
- icmp_pkt.ip.proto = IPPROTO_UDP;
- icmp_pkt.ip.src_ip = other->s_addr;
- icmp_pkt.ip.dst_ip = dummy.s_addr;
- icmp_pkt.ip.checksum = 0;
- icmp_pkt.ip.checksum = htons(calc_checksum((uint16_t*)&icmp_pkt.ip, sizeof (icmp_pkt.ip)));
- icmp_pkt.udp.source_port = htons (target_port_number);
- icmp_pkt.udp.dst_port = htons (NAT_TRAV_PORT);
- icmp_pkt.udp.mlen_aka_reply_port_magic = htons (source_port_number);
- icmp_pkt.udp.checksum_aka_my_magic = htons (target_port_number);
- icmp_pkt.checksum = htons(calc_checksum((uint16_t*)&icmp_pkt, sizeof (icmp_pkt)));
- memcpy (&packet[off], &icmp_pkt, sizeof (icmp_pkt));
- off += sizeof (icmp_pkt);
-
+ 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));
+ 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));
+ off += sizeof (struct icmp_echo_header);
+
memset (&dst, 0, sizeof (dst));
dst.sin_family = AF_INET;
- dst.sin_addr = *other;
- err = sendto(rawsock,
- packet,
- off, 0,
- (struct sockaddr*)&dst,
- sizeof(dst)); /* or sizeof 'struct sockaddr'? */
- if (err < 0) {
- fprintf(stderr,
- "sendto failed: %s\n", strerror(errno));
- } else if (err != off)
- fprintf(stderr,
- "Error: partial send of ICMP message\n");
+#if HAVE_SOCKADDR_IN_SIN_LEN
+ dst.sin_len = sizeof (struct sockaddr_in);
+#endif
+ dst.sin_addr = dummy;
+ err = sendto(rawsock,
+ packet, off, 0,
+ (struct sockaddr*)&dst,
+ sizeof(dst));
+ if (err < 0)
+ {
+#if VERBOSE
+ fprintf(stderr,
+ "sendto failed: %s\n", strerror(errno));
+#endif
+ }
+ else if (sizeof (packet) != err)
+ {
+ fprintf(stderr,
+ "Error: partial send of ICMP message\n");
+ }
}
/**
- * We discovered the IP address of the other peer.
- * Try to connect back to it.
+ * Send a UDP message to the dummy IP.
*/
static void
-try_connect (const struct in_addr *my_ip,
- const struct in_addr *other,
- uint16_t port_magic)
+send_udp ()
{
- unsigned int i;
-#if DEBUG
- char sbuf [INET_ADDRSTRLEN];
+ struct sockaddr_in dst;
+ ssize_t err;
- fprintf (stderr,
- "Sending %u ICMPs to `%s' with reply magic %u\n",
- NUM_ICMP_REPLIES,
- inet_ntop (AF_INET,
- other,
- sbuf,
- sizeof (sbuf)),
- port_magic);
+ memset (&dst, 0, sizeof (dst));
+ dst.sin_family = AF_INET;
+#if HAVE_SOCKADDR_IN_SIN_LEN
+ dst.sin_len = sizeof (struct sockaddr_in);
#endif
- for (i=0;i<NUM_ICMP_REPLIES;i++)
- send_icmp (my_ip, other, make_port(), port_magic);
+ dst.sin_addr = dummy;
+ dst.sin_port = htons (NAT_TRAV_PORT);
+ err = sendto(udpsock,
+ NULL, 0, 0,
+ (struct sockaddr*)&dst,
+ sizeof(dst));
+ if (err < 0)
+ {
+#if VERBOSE
+ fprintf(stderr,
+ "sendto failed: %s\n", strerror(errno));
+#endif
+ }
+ else if (0 != err)
+ {
+ fprintf(stderr,
+ "Error: partial send of ICMP message\n");
+ }
}
+/**
+ * We've received an ICMP response. Process it.
+ */
static void
-process_icmp_response (const struct in_addr *my_ip,
- int s)
+process_icmp_response ()
{
char buf[65536];
ssize_t have;
- struct in_addr sip;
- uint16_t my_magic;
- uint16_t reply_magic;
- uint16_t local_port;
- struct ip_packet ip_pkt;
- struct icmp_packet icmp_pkt;
+ struct in_addr source_ip;
+ struct ip_header ip_pkt;
+ struct icmp_ttl_exceeded_header icmp_ttl;
+ struct icmp_echo_header icmp_echo;
+ struct udp_header udp_pkt;
size_t off;
-
- have = read (s, buf, sizeof (buf));
- if (have == -1)
+ uint16_t port;
+
+ have = read (icmpsock, buf, sizeof (buf));
+ if (-1 == have)
{
fprintf (stderr,
"Error reading raw socket: %s\n",
strerror (errno));
- /* What now? */
- return;
- }
- if (have != sizeof (struct ip_packet) + sizeof (struct icmp_packet))
- {
- fprintf (stderr,
- "Received ICMP message of unexpected size: %u bytes\n",
- (unsigned int) have);
return;
}
- off = 0;
- memcpy (&ip_pkt, &buf[off], sizeof (ip_pkt));
- off += sizeof (ip_pkt);
- memcpy (&icmp_pkt, &buf[off], sizeof (icmp_pkt));
- off += sizeof (icmp_pkt);
-
- if ( (ip_pkt.proto == IPPROTO_ICMP) &&
- (icmp_pkt.type == ICMP_DEST_UNREACH) &&
- (icmp_pkt.code == ICMP_HOST_UNREACH) )
+#if VERBOSE
+ 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)))
{
- /* this is what is normal due to our UDP traffic */
+ /* malformed */
return;
}
- if ( (ip_pkt.proto == IPPROTO_ICMP) &&
- (icmp_pkt.type == ICMP_TIME_EXCEEDED) &&
- (icmp_pkt.code == ICMP_NET_UNREACH) )
+ off = 0;
+ 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));
+ off += sizeof (struct icmp_ttl_exceeded_header);
+ if ( (ICMP_TIME_EXCEEDED != icmp_ttl.type) ||
+ (0 != icmp_ttl.code) )
{
- /* this is what we might see on loopback: this is the format
- we as the server send out (the client uses 'ICMP_HOST_UNREACH');
- Ignore! */
+ /* different type than what we want */
return;
}
+ /* skip 2nd IP header */
+ memcpy (&ip_pkt,
+ &buf[off],
+ sizeof (struct ip_header));
+ off += sizeof (struct ip_header);
- if ( (ip_pkt.proto != IPPROTO_ICMP) ||
- (icmp_pkt.type != ICMP_TIME_EXCEEDED) ||
- (icmp_pkt.code != ICMP_HOST_UNREACH) )
+ switch (ip_pkt.proto)
{
- /* Note the expected client response and not the normal network response */
- fprintf (stderr,
- "Received unexpected ICMP message contents (%u, %u, %u), ignoring\n",
- ip_pkt.proto,
- icmp_pkt.type,
- icmp_pkt.code);
+ 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 */
return;
}
- memcpy(&sip, &ip_pkt.src_ip, sizeof (sip));
- reply_magic = ntohs (icmp_pkt.udp.checksum_aka_my_magic);
- my_magic = ntohs (icmp_pkt.udp.mlen_aka_reply_port_magic);
- local_port = ntohs (icmp_pkt.udp.source_port);
-#if DEBUG
- fprintf (stderr,
- "Received ICMP from `%s' with outgoing port %u, listen port %u and incoming port hint for other peer %u\n",
- inet_ntop (AF_INET,
- &sip,
- buf,
- sizeof (buf)),
- my_magic,
- local_port,
- reply_magic);
-#endif
- if (my_magic == 0)
- {
- try_connect (my_ip, &sip, reply_magic);
- }
+
+ if (port == 0)
+ fprintf (stdout,
+ "%s\n",
+ inet_ntop (AF_INET,
+ &source_ip,
+ buf,
+ sizeof (buf)));
else
- {
- /* FIXME: should close 'local_port' */
- printf ("%s:%u listen on %u\n",
- inet_ntop (AF_INET,
- &sip,
- buf,
- sizeof(buf)),
- my_magic,
- local_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.
+ *
+ * @return -1 on error
+ */
static int
make_icmp_socket ()
{
"Error opening RAW socket: %s\n",
strerror (errno));
return -1;
- }
- if (ret >= FD_SETSIZE)
+ }
+ if (ret >= FD_SETSIZE)
{
fprintf (stderr,
"Socket number too large (%d > %u)\n",
}
+/**
+ * Create an ICMP raw socket for writing.
+ *
+ * @return -1 on error
+ */
static int
make_raw_socket ()
{
"Error opening RAW socket: %s\n",
strerror (errno));
return -1;
- }
- if (ret >= FD_SETSIZE)
+ }
+ if (-1 == setsockopt(ret,
+ SOL_SOCKET,
+ SO_BROADCAST,
+ (char *)&one, sizeof(one)))
{
- fprintf (stderr,
- "Socket number too large (%d > %u)\n",
- ret,
- (unsigned int) FD_SETSIZE);
+ 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;
}
- if (setsockopt(ret, SOL_SOCKET, SO_BROADCAST,
- (char *)&one, sizeof(one)) == -1)
- fprintf(stderr,
- "setsockopt failed: %s\n",
- strerror (errno));
- if (setsockopt(ret, IPPROTO_IP, IP_HDRINCL,
- (char *)&one, sizeof(one)) == -1)
- fprintf(stderr,
- "setsockopt failed: %s\n",
- strerror (errno));
+ return ret;
+}
+
+
+/**
+ * Create a UDP socket for writinging.
+ *
+ * @param my_ip source address (our ip address)
+ * @return -1 on error
+ */
+static int
+make_udp_socket (const struct in_addr *my_ip)
+{
+ int ret;
+ struct sockaddr_in addr;
+
+ 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));
+ addr.sin_family = AF_INET;
+#if HAVE_SOCKADDR_IN_SIN_LEN
+ addr.sin_len = sizeof (struct sockaddr_in);
+#endif
+ 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 */
+ }
return ret;
}
int
-main (int argc, char *const *argv)
+main (int argc,
+ char *const *argv)
{
struct in_addr external;
- unsigned int i;
- unsigned int pos;
fd_set rs;
struct timeval tv;
- struct sockaddr_in dst;
-
- if (argc != 3)
+ uid_t uid;
+ unsigned int alt;
+
+ if (2 != argc)
{
fprintf (stderr,
- "This program must be started with our external IP and the dummy IP address as arguments.\n");
+ "This program must be started with our (internal NAT) IP as the only argument.\n");
return 1;
}
- if ( (1 != inet_pton (AF_INET, argv[1], &external)) ||
- (1 != inet_pton (AF_INET, argv[2], &dummy)) )
+ if (1 != inet_pton (AF_INET, argv[1], &external))
{
fprintf (stderr,
- "Error parsing IPv4 address: %s\n",
- strerror (errno));
+ "Error parsing IPv4 address: %s\n",
+ strerror (errno));
return 1;
}
- srand (time(NULL));
- memset (&dst, 0, sizeof (dst));
- dst.sin_family = AF_INET;
- dst.sin_port = htons (NAT_TRAV_PORT);
- dst.sin_addr = dummy;
-
+ 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 1;
+ {
+ return 3;
+ }
if (-1 == (rawsock = make_raw_socket()))
{
close (icmpsock);
- return 1;
+ return 3;
}
- for (i=0;i<NUM_UDP_PORTS;i++)
- udpsocks[i] = make_udp_socket (&udpports[i]);
- pos = 0;
+ 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;
+ }
+ alt = 0;
while (1)
{
FD_ZERO (&rs);
FD_SET (icmpsock, &rs);
tv.tv_sec = 0;
- tv.tv_usec = UDP_SEND_FREQUENCY_MS * 1000;
- select (icmpsock + 1, &rs, NULL, NULL, &tv);
- /* FIXME: do I need my external IP here? */
- if (FD_ISSET (icmpsock, &rs))
- {
- process_icmp_response (&external, icmpsock);
- continue;
- }
-#if DEBUG
- fprintf (stderr,
- "Sending UDP message to %s:%u\n",
- argv[2],
- NAT_TRAV_PORT);
-#endif
- if (-1 == sendto (udpsocks[pos],
- NULL, 0, 0,
- (struct sockaddr*) &dst, sizeof (dst)))
+ tv.tv_usec = ICMP_SEND_FREQUENCY_MS * 1000;
+ if (-1 == select (icmpsock + 1, &rs, NULL, NULL, &tv))
{
- fprintf (stderr,
- "sendto failed: %s\n",
+ if (errno == EINTR)
+ continue;
+ fprintf (stderr,
+ "select failed: %s\n",
strerror (errno));
- close (udpsocks[pos]);
- udpsocks[pos] = make_udp_socket (&udpports[pos]);
+ break;
}
- pos = (pos+1) % NUM_UDP_PORTS;
- }
- return 0;
+ 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;
}
projects / oweals / gnunet.git / blobdiff