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authorChristian Grothoff <christian@grothoff.org>2011-07-01 08:46:27 +0000
committerChristian Grothoff <christian@grothoff.org>2011-07-01 08:46:27 +0000
commit11a2d8cd5b619a0fea63e766585c6ec4687a0707 (patch)
tree0b18ea0e567fd7bf5ca50b5994df5abe1ba77d95 /src/nat/gnunet-nat-server.c
parent9b986bcca579585f4f113d22b7c841a2ab28de0c (diff)
renaming gnunet-nat-server/client for consistency, other minor fixes
Diffstat (limited to 'src/nat/gnunet-nat-server.c')
-rw-r--r--src/nat/gnunet-nat-server.c631
1 files changed, 25 insertions, 606 deletions
diff --git a/src/nat/gnunet-nat-server.c b/src/nat/gnunet-nat-server.c
index ffc570146..c1f1be668 100644
--- a/src/nat/gnunet-nat-server.c
+++ b/src/nat/gnunet-nat-server.c
@@ -20,49 +20,12 @@
/**
* @file src/nat/gnunet-nat-server.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 (or maybe BSDs, but never W32)
+ * @brief Daemon to run on 'gnunet.org' to help test NAT traversal code
* @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)
*/
-#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 <sys/time.h>
-#include <sys/types.h>
-#include <unistd.h>
-#include <stdio.h>
-#include <string.h>
-#include <errno.h>
-#include <stdlib.h>
-#include <stdint.h>
-#include <time.h>
-#include <netinet/ip.h>
-#include <netinet/ip_icmp.h>
-#include <netinet/in.h>
+#include "platform.h"
+#include "gnunet_util_lib.h"
/**
* Should we print some debug output?
@@ -70,581 +33,37 @@
#define VERBOSE 0
/**
- * Must match IP given in the client.
- */
-#define DUMMY_IP "192.0.2.86"
-
-/**
- * Port for UDP
- */
-#define NAT_TRAV_PORT 22225
-
-/**
- * How often do we send our ICMP messages to receive replies?
- */
-#define ICMP_SEND_FREQUENCY_MS 500
-
-/**
- * IPv4 header.
- */
-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;
-};
-
-/**
- * Format of ICMP packet.
- */
-struct icmp_ttl_exceeded_header
-{
- uint8_t type;
-
- uint8_t code;
-
- uint16_t checksum;
-
- uint32_t unused;
-
- /* followed by original payload */
-};
-
-struct icmp_echo_header
-{
- uint8_t type;
-
- uint8_t code;
-
- uint16_t checksum;
-
- uint32_t reserved;
-};
-
-
-/**
- * Beginning of UDP packet.
- */
-struct udp_header
-{
- uint16_t src_port;
-
- uint16_t dst_port;
-
- uint16_t length;
-
- uint16_t crc;
-};
-
-/**
- * Socket we use to receive "fake" ICMP replies.
- */
-static int icmpsock;
-
-/**
- * Socket we use to send our ICMP requests.
- */
-static int rawsock;
-
-/**
- * Socket we use to send our UDP requests.
- */
-static int udpsock;
-
-/**
- * Target "dummy" address.
- */
-static struct in_addr dummy;
-
-
-/**
- * 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];
- sum = (sum & 0xffff) + (sum >> 16);
- sum = htons(0xffff - sum);
- return sum;
-}
-
-
-/**
- * Send an ICMP message to the dummy IP.
+ * Main function that will be run.
*
- * @param my_ip source address (our ip address)
- */
-static void
-send_icmp_echo (const struct in_addr *my_ip)
-{
- 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;
- 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);
- 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));
- 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;
-#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");
- }
-}
-
-
-/**
- * Send a UDP message to the dummy IP.
- */
-static void
-send_udp ()
-{
- struct sockaddr_in dst;
- ssize_t err;
-
- memset (&dst, 0, sizeof (dst));
- dst.sin_family = AF_INET;
-#if HAVE_SOCKADDR_IN_SIN_LEN
- dst.sin_len = sizeof (struct sockaddr_in);
-#endif
- 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.
+ * @param cls closure
+ * @param args remaining command-line arguments
+ * @param cfgfile name of the configuration file used (for saving, can be NULL!)
+ * @param c configuration
*/
static void
-process_icmp_response ()
-{
- char buf[65536];
- ssize_t have;
- 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;
- uint16_t port;
-
- have = read (icmpsock, buf, sizeof (buf));
- if (-1 == have)
- {
- fprintf (stderr,
- "Error reading raw socket: %s\n",
- strerror (errno));
- return;
- }
-#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)))
- {
- /* malformed */
- return;
- }
- 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) )
- {
- /* 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);
-
- 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)) )
- {
- /* 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)));
- else
- 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 ()
-{
- 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 ()
-{
- 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;
-}
-
-
-/**
- * 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)
+run (void *cls,
+ char *const *args,
+ const char *cfgfile,
+ const struct GNUNET_CONFIGURATION_Handle * c)
{
- 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;
- fd_set rs;
- struct timeval tv;
- uid_t uid;
- unsigned int alt;
-
- if (2 != argc)
- {
- fprintf (stderr,
- "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))
- {
- fprintf (stderr,
- "Error parsing IPv4 address: %s\n",
- strerror (errno));
- return 1;
- }
- 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;
- }
- 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))
- {
- 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;
+ static const struct GNUNET_GETOPT_CommandLineOption options[] = {
+ GNUNET_GETOPT_OPTION_END
+ };
+
+ if (GNUNET_OK !=
+ GNUNET_PROGRAM_run (argc, argv,
+ "gnunet-nat-server",
+ _("GNUnet NAT traversal test helper daemon"),
+ options,
+ &run, NULL))
+ return 1;
+ return 0;
}