From 11a2d8cd5b619a0fea63e766585c6ec4687a0707 Mon Sep 17 00:00:00 2001 From: Christian Grothoff Date: Fri, 1 Jul 2011 08:46:27 +0000 Subject: renaming gnunet-nat-server/client for consistency, other minor fixes --- src/nat/gnunet-helper-nat-client-windows.c | 550 +++++++++++++++++++++++++++++ 1 file changed, 550 insertions(+) create mode 100644 src/nat/gnunet-helper-nat-client-windows.c (limited to 'src/nat/gnunet-helper-nat-client-windows.c') diff --git a/src/nat/gnunet-helper-nat-client-windows.c b/src/nat/gnunet-helper-nat-client-windows.c new file mode 100644 index 000000000..0717eecfe --- /dev/null +++ b/src/nat/gnunet-helper-nat-client-windows.c @@ -0,0 +1,550 @@ +/* + 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/nat/gnunet-helper-nat-client-windows.c + * @brief Tool to help bypass NATs using ICMP method; must run as + * administrator on W32 + * This code is forx W32. + * @author Nathan Evans + * + * This program will send ONE ICMP message using RAW sockets + * to the IP address specified as the second argument. 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 RAW socket 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 + */ +#define _GNU_SOURCE + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + + +#define ICMP_ECHO 8 +#define IPDEFTTL 64 +#define ICMP_TIME_EXCEEDED 11 + +/** + * Must match IP given in the server. + */ +#define DUMMY_IP "192.0.2.86" + +#define NAT_TRAV_PORT 22225 + +/** + * 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 send our ICMP packets. + */ +static SOCKET rawsock; + +/** + * Target "dummy" address. + */ +static struct in_addr dummy; + +/** + * Port we are listening on (communicated to the server). + */ +static uint16_t port; + + + +/** + * Convert IPv4 address from text to binary form. + * + * @param af address family + * @param cp the address to print + * @param buf where to write the address result + * @return 1 on success + */ +static int +inet_pton (int af, + const char *cp, + struct in_addr *buf) +{ + buf->s_addr = inet_addr(cp); + if (buf->s_addr == INADDR_NONE) + { + fprintf(stderr, + "Error %d handling address %s", + WSAGetLastError(), + cp); + return 0; + } + return 1; +} + + +/** + * 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> 16); + sum = htons(0xffff - sum); + return sum; +} + + +/** + * Send an ICMP message to the target. + * + * @param my_ip source address + * @param other target address + */ +static void +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)]; + struct ip_header ip_pkt; + struct icmp_ttl_exceeded_header icmp_pkt; + struct udp_header udp_pkt; + struct sockaddr_in dst; + size_t off; + int err; + + /* ip header: send to (known) ip address */ + 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 = 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)); + 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)); + 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.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)); + 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 (port); + udp_pkt.crc = 0; + memcpy(&packet[off], + &udp_pkt, + sizeof(struct udp_header)); + off += sizeof(struct udp_header); + + /* no go back to calculate ICMP packet checksum */ + icmp_pkt.checksum = htons(calc_checksum((uint16_t*)&packet[off], + 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)); + dst.sin_family = AF_INET; + dst.sin_addr = *other; + 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"); + } +} + + +/** + * Send an ICMP message to the target. + * + * @param my_ip source address + * @param other target address + */ +static void +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)]; + size_t off; + int err; + + /* ip header: send to (known) ip address */ + 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 = 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); + + /* 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); + + /* 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.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.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); + + 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)); + + /* 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)); + + memset (&dst, 0, sizeof (dst)); + dst.sin_family = AF_INET; + dst.sin_addr = *other; + + 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. + * + * @return INVALID_SOCKET on error + */ +static SOCKET +make_raw_socket () +{ + DWORD bOptVal = TRUE; + int bOptLen = sizeof(bOptVal); + SOCKET ret; + + ret = socket (AF_INET, SOCK_RAW, IPPROTO_RAW); + if (INVALID_SOCKET == ret) + { + fprintf (stderr, + "Error opening RAW socket: %s\n", + strerror (errno)); + return INVALID_SOCKET; + } + if (0 != setsockopt(ret, SOL_SOCKET, SO_BROADCAST, (char*)&bOptVal, bOptLen)) + { + fprintf(stderr, + "Error setting SO_BROADCAST to ON: %s\n", + strerror (errno)); + closesocket(rawsock); + return INVALID_SOCKET; + } + + if (0 != setsockopt(ret, IPPROTO_IP, IP_HDRINCL, (char*)&bOptVal, bOptLen)) + { + fprintf(stderr, + "Error setting IP_HDRINCL to ON: %s\n", + strerror (errno)); + closesocket(rawsock); + return INVALID_SOCKET; + } + return ret; +} + + +int +main (int argc, char *const *argv) +{ + struct in_addr external; + struct in_addr target; + WSADATA wsaData; + + unsigned int p; + + if (argc != 4) + { + 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; + } + port = (uint16_t) p; + + if (0 != WSAStartup (MAKEWORD (2, 1), &wsaData)) + { + fprintf (stderr, "Failed to find Winsock 2.1 or better.\n"); + return 2; + } + 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 3; + send_icmp (&external, + &target); + send_icmp_udp (&external, + &target); + closesocket (rawsock); + WSACleanup (); + return 0; +} + +/* end of gnunet-helper-nat-client-windows.c */ -- cgit v1.2.3