[GNUnet-SVN] r12595 - gnunet/src/transport

[gnunet]

Author: nevans
Date: 2010-08-18 14:54:33 +0200 (Wed, 18 Aug 2010)
New Revision: 12595

Added:
   gnunet/src/transport/gnunet-nat-server-windows.c
Log:
initial try at windows version

Added: gnunet/src/transport/gnunet-nat-server-windows.c
===================================================================
--- gnunet/src/transport/gnunet-nat-server-windows.c                            
(rev 0)
+++ gnunet/src/transport/gnunet-nat-server-windows.c    2010-08-18 12:54:33 UTC 
(rev 12595)
@@ -0,0 +1,425 @@
+/*
+     This file is part of GNUnet.
+     (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
+     by the Free Software Foundation; either version 3, 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.
+
+     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.
+*/
+
+/**
+ * @file src/transport/gnunet-nat-server-windows.c
+ * @brief Windows tool to help bypass NATs using ICMP method
+ *        This code will work under W32 only
+ * @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 run as an administrative user.
+ * In order to keep the security risk of the resulting binary
+ * minimal, the program ONLY opens the two RAW sockets with administrative
+ * 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):
+ *
+ * - Nathan Evans
+ */
+#define _GNU_SOURCE
+#ifdef WIN32
+#include <winsock2.h>
+#else
+#include <sys/types.h> 
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <sys/select.h>
+#include <netinet/ip.h>
+#include <netinet/ip_icmp.h>
+#include <netinet/in.h>
+#endif
+#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>
+
+#ifdef WIN32
+typedef SOCKET Socket;
+typedef unsigned short ushort;
+#else
+typedef int Socket;
+#endif
+
+/**
+ * Must match IP given in the client.
+ */
+#define DUMMY_IP "192.0.2.86"
+
+#define VERBOSE 0
+
+/**
+ * How often do we send our ICMP messages to receive replies?
+ */
+#define ICMP_SEND_FREQUENCY_MS 500
+
+struct ip_packet 
+{
+  uint8_t vers_ihl;
+  uint8_t tos;
+  uint16_t pkt_len;
+  uint16_t id;
+  uint16_t flags_frag_offset;
+  uint8_t ttl;
+  uint8_t proto;
+  uint16_t checksum;
+  uint32_t src_ip;
+  uint32_t dst_ip;
+};
+
+struct icmp_packet 
+{
+  uint8_t type;
+  uint8_t code;
+  uint16_t checksum;
+  uint32_t reserved;
+};
+
+struct udp_packet
+{
+  uint16_t src_port;
+
+  uint16_t dst_port;
+
+  uint32_t length;
+};
+
+static Socket icmpsock;
+
+static Socket rawsock;
+
+static struct in_addr dummy;
+
+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;
+}
+
+
+static void
+make_echo (const struct in_addr *src_ip,
+          struct icmp_packet *echo)
+{
+  memset(echo, 0, sizeof(struct icmp_packet));
+  echo->type = ICMP_ECHO;
+  echo->code = 0;
+  echo->reserved = 0;
+  echo->checksum = 0;
+  echo->checksum = htons(calc_checksum((uint16_t*)echo, sizeof (struct 
icmp_packet)));
+}
+
+
+/**
+ * Send an ICMP message to the dummy IP.
+ *
+ * @param my_ip source address (our ip address)
+ */
+static void
+send_icmp_echo (const struct in_addr *my_ip)
+{
+  struct icmp_packet icmp_echo;
+  struct sockaddr_in dst;
+  size_t off;
+  int err;
+  struct ip_packet ip_pkt;
+  struct icmp_packet icmp_pkt;
+  char packet[sizeof (ip_pkt) + sizeof (icmp_pkt)];
+
+  off = 0;
+  memset(&ip_pkt, 0, sizeof(ip_pkt));
+  ip_pkt.vers_ihl = 0x45;
+  ip_pkt.tos = 0;
+  ip_pkt.pkt_len = sizeof (packet);
+  ip_pkt.id = 1;
+  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 (ip_pkt)));
+  memcpy (packet, &ip_pkt, sizeof (ip_pkt));
+  off += sizeof (ip_pkt);
+  make_echo (my_ip, &icmp_echo);
+  memcpy (&packet[off], &icmp_echo, sizeof (icmp_echo));
+  off += sizeof (icmp_echo);
+ 
+  memset (&dst, 0, sizeof (dst));
+  dst.sin_family = AF_INET;
+  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 (err != off) 
+    {
+      fprintf(stderr,
+             "Error: partial send of ICMP message\n");
+    }
+}
+
+
+static void
+process_icmp_response ()
+{
+  char buf[65536];
+  ssize_t have;
+  struct in_addr sip;
+  struct ip_packet ip_pkt;
+  struct icmp_packet icmp_pkt;
+  struct udp_packet udp_pkt;
+  size_t off;
+  int have_port;
+  int have_udp;
+  uint32_t port;
+  
+  have = read (icmpsock, buf, sizeof (buf));
+  if (have == -1)
+    {
+      fprintf (stderr,
+              "Error reading raw socket: %s\n",
+              strerror (errno));
+      return; 
+    }
+  have_port = 0;
+
+  if (have == sizeof (struct ip_packet) *2 + sizeof (struct icmp_packet) * 2 + 
sizeof(uint32_t))
+    {
+      have_port = 1;
+    }
+  else if (have != sizeof (struct ip_packet) *2 + sizeof (struct icmp_packet) 
* 2)
+    {
+#if VERBOSE
+      fprintf (stderr,
+              "Received ICMP message of unexpected size: %u bytes\n",
+              (unsigned int) have);
+#endif
+      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) && (ip_pkt.proto != IPPROTO_UDP)) ||
+       (icmp_pkt.type != ICMP_TIME_EXCEEDED) || 
+       (icmp_pkt.code != 0) )
+    {
+      /* maybe we got an actual reply back... */
+      return;    
+    }
+  memcpy(&sip, 
+        &ip_pkt.src_ip, 
+        sizeof (sip));
+
+  memcpy (&ip_pkt, &buf[off], sizeof (ip_pkt));
+  off += sizeof (ip_pkt);
+
+  have_udp = 0;
+  if (ip_pkt.proto == IPPROTO_UDP)
+    {
+      have_udp = 1;
+    }
+
+  if (have_port)
+    {
+      memcpy(&port, &buf[sizeof (struct ip_packet) *2 + sizeof (struct 
icmp_packet) * 2], sizeof(uint32_t));
+      port = ntohs(port);
+      fprintf (stdout,
+              "%s:%d\n",
+              inet_ntop (AF_INET,
+                         &sip,
+                         buf,
+                         sizeof (buf)), port);
+    }
+  else if (have_udp)
+    {
+      memcpy(&udp_pkt, &buf[off], sizeof(udp_pkt));
+      fprintf (stdout,
+               "%s:%d\n",
+               inet_ntop (AF_INET,
+                          &sip,
+                          buf,
+                          sizeof (buf)), ntohl(udp_pkt.length));
+    }
+  else
+    {
+      fprintf (stdout,
+              "%s\n",
+              inet_ntop (AF_INET,
+                         &sip,
+                         buf,
+                         sizeof (buf)));
+    }
+  fflush (stdout);
+}
+
+
+static Socket
+make_icmp_socket ()
+{
+  Socket 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);
+#ifdef WIN32
+      closesocket (ret);
+#else
+      close (ret);
+#endif
+      return -1;
+    }
+  return ret;
+}
+
+
+static Socket
+make_raw_socket ()
+{
+  const int one = 1;
+  Socket 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 (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;
+}
+
+
+int
+main (int argc, char *const *argv)
+{
+  struct in_addr external;
+  fd_set rs;
+  struct timeval tv;
+  uid_t uid;
+
+#ifdef WIN32
+    // WSA startup
+    WSAData wsaData;
+    if (WSAStartup (MAKEWORD (2, 1), &wsaData) != 0)
+    {
+        fprintf (stderr, "Failed to find Winsock 2.1 or better.\n");
+        return 4;                       // ERROR
+    }
+#endif
+
+  if (-1 == (icmpsock = make_icmp_socket()))
+    return 1; 
+  if (-1 == (rawsock = make_raw_socket()))
+    {
+      close (icmpsock);
+      return 1; 
+    }
+  uid = getuid ();
+  if (0 != setresuid (uid, uid, uid))
+    fprintf (stderr,
+            "Failed to setresuid: %s\n",
+            strerror (errno));    
+  if (argc != 2)
+    {
+      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)) abort ();
+  while (1)
+    {
+      FD_ZERO (&rs);
+      FD_SET (icmpsock, &rs);
+      tv.tv_sec = 0;
+      tv.tv_usec = ICMP_SEND_FREQUENCY_MS * 1000; 
+      select (icmpsock + 1, &rs, NULL, NULL, &tv);
+      if (FD_ISSET (icmpsock, &rs))
+       process_icmp_response ();
+      send_icmp_echo (&external);
+    }  
+
+#ifdef WIN32
+  closesocket(icmpsock);
+  closesocket(rawsock);
+  WSACleanup ();
+#endif
+  return 0;
+}
+
+
+/* end of gnunet-nat-server-windows.c */