mirror of
https://github.com/yarrick/iodine.git
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636 lines
12 KiB
C
636 lines
12 KiB
C
/*
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* Copyright (c) 2006-2007 Bjorn Andersson <flex@kryo.se>, Erik Ekman <yarrick@kryo.se>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <stdio.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <signal.h>
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#include <unistd.h>
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#include <netdb.h>
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#include <netinet/in.h>
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#include <sys/types.h>
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#include <sys/time.h>
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#include <sys/socket.h>
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#include <fcntl.h>
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#include <err.h>
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#include <pwd.h>
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#include <arpa/inet.h>
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#include <zlib.h>
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#include <arpa/nameser.h>
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#ifdef DARWIN
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#include <arpa/nameser8_compat.h>
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#endif
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#include "common.h"
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#include "encoding.h"
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#include "base32.h"
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#include "dns.h"
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#include "login.h"
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#include "tun.h"
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#include "version.h"
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static void send_ping(int fd);
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static void send_chunk(int fd);
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static int build_hostname(char *buf, size_t buflen,
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const char *data, const size_t datalen,
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const char *topdomain, struct encoder *encoder);
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int running = 1;
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char password[33];
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struct sockaddr_in peer;
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static char *topdomain;
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uint16_t rand_seed;
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/* Current IP packet */
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static struct packet packet;
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static char userid;
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static uint16_t chunkid;
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/* Base32 encoder used for non-data packets */
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static struct encoder *b32;
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/* The encoder used for data packets
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* Defaults to Base32, can be changed after handshake */
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static struct encoder *dataenc;
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static void
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sighandler(int sig)
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{
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running = 0;
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}
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static void
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send_packet(int fd, char cmd, const char *data, const size_t datalen)
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{
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char packet[4096];
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struct query q;
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char buf[4096];
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size_t len;
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q.id = ++chunkid;
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q.type = T_NULL;
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buf[0] = cmd;
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len = build_hostname(buf + 1, sizeof(buf) - 1, data, datalen, topdomain, b32);
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len = dns_encode(packet, sizeof(packet), &q, QR_QUERY, buf, strlen(buf));
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sendto(fd, packet, len, 0, (struct sockaddr*)&peer, sizeof(peer));
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}
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static int
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build_hostname(char *buf, size_t buflen,
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const char *data, const size_t datalen,
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const char *topdomain, struct encoder *encoder)
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{
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int encsize;
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size_t space;
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char *b;
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space = MIN(0xFF, buflen) - strlen(topdomain) - 2;
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if (!encoder->places_dots())
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space -= (space / 62); /* space for dots */
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memset(buf, 0, buflen);
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encsize = encoder->encode(buf, &space, data, datalen);
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if (!encoder->places_dots())
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inline_dotify(buf, buflen);
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b = buf;
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b += strlen(buf);
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if (*b != '.')
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*b++ = '.';
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strncpy(b, topdomain, strlen(topdomain)+1);
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return space;
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}
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int
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is_sending()
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{
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return (packet.len != 0);
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}
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int
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read_dns(int fd, char *buf, int buflen)
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{
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struct sockaddr_in from;
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char data[64*1024];
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socklen_t addrlen;
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struct query q;
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int rv;
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int r;
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addrlen = sizeof(struct sockaddr);
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if ((r = recvfrom(fd, data, sizeof(data), 0,
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(struct sockaddr*)&from, &addrlen)) == -1) {
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warn("recvfrom");
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return 0;
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}
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rv = dns_decode(buf, buflen, &q, QR_ANSWER, data, r);
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if (is_sending() && chunkid == q.id) {
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/* Got ACK on sent packet */
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packet.offset += packet.sentlen;
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if (packet.offset == packet.len) {
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/* Packet completed */
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packet.offset = 0;
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packet.len = 0;
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packet.sentlen = 0;
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} else {
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/* More to send */
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send_chunk(fd);
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}
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}
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return rv;
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}
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static int
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tunnel_tun(int tun_fd, int dns_fd)
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{
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unsigned long outlen;
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unsigned long inlen;
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char out[64*1024];
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char in[64*1024];
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size_t read;
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if ((read = read_tun(tun_fd, in, sizeof(in))) <= 0)
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return -1;
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outlen = sizeof(out);
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inlen = read;
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compress2((uint8_t*)out, &outlen, (uint8_t*)in, inlen, 9);
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memcpy(packet.data, out, MIN(outlen, sizeof(packet.data)));
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packet.sentlen = 0;
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packet.offset = 0;
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packet.len = outlen;
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send_chunk(dns_fd);
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return read;
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}
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static int
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tunnel_dns(int tun_fd, int dns_fd)
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{
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unsigned long outlen;
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unsigned long inlen;
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char out[64*1024];
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char in[64*1024];
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size_t read;
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if ((read = read_dns(dns_fd, in, sizeof(in))) <= 0)
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return -1;
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outlen = sizeof(out);
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inlen = read;
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if (uncompress((uint8_t*)out, &outlen, (uint8_t*)in, inlen) != Z_OK)
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return -1;
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write_tun(tun_fd, out, outlen);
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if (!is_sending())
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send_ping(dns_fd);
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return read;
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}
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static int
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tunnel(int tun_fd, int dns_fd)
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{
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struct timeval tv;
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fd_set fds;
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int rv;
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int i;
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rv = 0;
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while (running) {
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tv.tv_sec = 1;
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tv.tv_usec = 0;
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FD_ZERO(&fds);
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if (!is_sending())
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FD_SET(tun_fd, &fds);
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FD_SET(dns_fd, &fds);
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i = select(MAX(tun_fd, dns_fd) + 1, &fds, NULL, NULL, &tv);
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if (running == 0)
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break;
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if (i < 0)
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err(1, "select");
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if (i == 0) /* timeout */
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send_ping(dns_fd);
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else {
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if (FD_ISSET(tun_fd, &fds)) {
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if (tunnel_tun(tun_fd, dns_fd) <= 0)
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continue;
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}
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if (FD_ISSET(dns_fd, &fds)) {
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if (tunnel_dns(tun_fd, dns_fd) <= 0)
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continue;
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}
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}
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}
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return rv;
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}
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static void
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send_chunk(int fd)
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{
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char hex[] = "0123456789ABCDEF";
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char data[4096];
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struct query q;
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char buf[4096];
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int avail;
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int code;
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char *p;
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int len;
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q.id = ++chunkid;
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q.type = T_NULL;
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p = packet.data;
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p += packet.offset;
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avail = packet.len - packet.offset;
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packet.sentlen = build_hostname(buf + 1, sizeof(buf) - 1, p, avail, topdomain, dataenc);
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if (packet.sentlen == avail)
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code = 1;
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else
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code = 0;
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code |= (userid << 1);
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buf[0] = hex[code];
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len = dns_encode(data, sizeof(data), &q, QR_QUERY, buf, strlen(buf));
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sendto(fd, data, len, 0, (struct sockaddr*)&peer, sizeof(peer));
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}
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void
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send_login(int fd, char *login, int len)
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{
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char data[19];
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memset(data, 0, sizeof(data));
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data[0] = userid;
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memcpy(&data[1], login, MIN(len, 16));
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data[17] = (rand_seed >> 8) & 0xff;
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data[18] = (rand_seed >> 0) & 0xff;
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rand_seed++;
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send_packet(fd, 'L', data, sizeof(data));
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}
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static void
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send_ping(int fd)
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{
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char data[3];
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if (is_sending()) {
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packet.sentlen = 0;
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packet.offset = 0;
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packet.len = 0;
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}
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data[0] = userid;
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data[1] = (rand_seed >> 8) & 0xff;
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data[2] = (rand_seed >> 0) & 0xff;
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rand_seed++;
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send_packet(fd, 'P', data, sizeof(data));
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}
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void
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send_version(int fd, uint32_t version)
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{
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char data[6];
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data[0] = (version >> 24) & 0xff;
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data[1] = (version >> 16) & 0xff;
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data[2] = (version >> 8) & 0xff;
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data[3] = (version >> 0) & 0xff;
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data[4] = (rand_seed >> 8) & 0xff;
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data[5] = (rand_seed >> 0) & 0xff;
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rand_seed++;
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send_packet(fd, 'V', data, sizeof(data));
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}
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static int
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handshake(int dns_fd)
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{
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struct timeval tv;
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uint32_t payload;
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char server[65];
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char client[65];
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char login[16];
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char in[4096];
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fd_set fds;
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int read;
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int mtu;
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int seed;
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int i;
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int r;
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for (i = 0; running && i < 5; i++) {
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tv.tv_sec = i + 1;
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tv.tv_usec = 0;
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send_version(dns_fd, VERSION);
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FD_ZERO(&fds);
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FD_SET(dns_fd, &fds);
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r = select(dns_fd + 1, &fds, NULL, NULL, &tv);
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if(r > 0) {
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read = read_dns(dns_fd, in, sizeof(in));
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if(read < 0) {
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perror("read");
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continue;
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}
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if (read >= 9) {
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payload = (((in[4] & 0xff) << 24) |
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((in[5] & 0xff) << 16) |
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((in[6] & 0xff) << 8) |
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((in[7] & 0xff)));
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if (strncmp("VACK", in, 4) == 0) {
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seed = payload;
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userid = in[8];
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printf("Version ok, both running 0x%08x. You are user #%d\n", VERSION, userid);
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goto perform_login;
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} else if (strncmp("VNAK", in, 4) == 0) {
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errx(1, "you run 0x%08x, server runs 0x%08x. giving up\n",
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VERSION, payload);
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/* NOTREACHED */
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} else if (strncmp("VFUL", in, 4) == 0) {
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errx(1, "server full, all %d slots are taken. try again later\n", payload);
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/* NOTREACHED */
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}
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} else
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warnx("did not receive proper login challenge\n");
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}
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printf("Retrying version check...\n");
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}
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errx(1, "couldn't connect to server");
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/* NOTREACHED */
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perform_login:
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login_calculate(login, 16, password, seed);
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for (i=0; running && i<5 ;i++) {
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tv.tv_sec = i + 1;
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tv.tv_usec = 0;
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send_login(dns_fd, login, 16);
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FD_ZERO(&fds);
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FD_SET(dns_fd, &fds);
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r = select(dns_fd + 1, &fds, NULL, NULL, &tv);
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if(r > 0) {
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read = read_dns(dns_fd, in, sizeof(in));
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if(read <= 0) {
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warn("read");
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continue;
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}
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if (read > 0) {
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if (strncmp("LNAK", in, 4) == 0) {
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printf("Bad password\n");
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return 1;
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} else if (sscanf(in, "%64[^-]-%64[^-]-%d",
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server, client, &mtu) == 3) {
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server[64] = 0;
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client[64] = 0;
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if (tun_setip(client) == 0 &&
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tun_setmtu(mtu) == 0) {
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return 0;
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} else {
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warnx("Received handshake with bad data");
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}
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} else {
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printf("Received bad handshake\n");
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}
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}
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}
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printf("Retrying login...\n");
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}
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return 1;
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}
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static void
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set_target(const char *host)
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{
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struct hostent *h;
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h = gethostbyname(host);
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if (!h)
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err(1, "couldn't resolve name %s", host);
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memset(&peer, 0, sizeof(peer));
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peer.sin_family = AF_INET;
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peer.sin_port = htons(53);
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peer.sin_addr = *((struct in_addr *) h->h_addr);
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}
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static void
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usage() {
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extern char *__progname;
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printf("Usage: %s [-v] [-h] [-f] [-u user] [-t chrootdir] [-d device] "
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"nameserver topdomain\n", __progname);
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exit(2);
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}
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static void
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help() {
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extern char *__progname;
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printf("iodine IP over DNS tunneling client\n");
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printf("Usage: %s [-v] [-h] [-f] [-u user] [-t chrootdir] [-d device] "
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"[-P password] nameserver topdomain\n", __progname);
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printf(" -v to print version info and exit\n");
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printf(" -h to print this help and exit\n");
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printf(" -f to keep running in foreground\n");
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printf(" -u name to drop privileges and run as user 'name'\n");
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printf(" -t dir to chroot to directory dir\n");
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printf(" -d device to set tunnel device name\n");
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printf(" -P password used for authentication (max 32 chars will be used)\n");
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printf("nameserver is the IP number of the relaying nameserver\n");
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printf("topdomain is the FQDN that is delegated to the tunnel endpoint.\n");
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exit(0);
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}
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static void
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version() {
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char *svnver;
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svnver = "$Rev$ from $Date$";
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printf("iodine IP over DNS tunneling client\n");
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printf("SVN version: %s\n", svnver);
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exit(0);
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}
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int
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main(int argc, char **argv)
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{
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struct passwd *pw;
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char *username;
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int foreground;
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char *newroot;
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char *device;
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int choice;
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int tun_fd;
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int dns_fd;
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memset(password, 0, 33);
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username = NULL;
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foreground = 0;
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newroot = NULL;
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device = NULL;
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chunkid = 0;
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b32 = get_base32_encoder();
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dataenc = get_base32_encoder();
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while ((choice = getopt(argc, argv, "vfhu:t:d:P:")) != -1) {
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switch(choice) {
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case 'v':
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version();
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break;
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case 'f':
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foreground = 1;
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break;
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case 'h':
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help();
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break;
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case 'u':
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username = optarg;
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break;
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case 't':
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newroot = optarg;
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break;
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case 'd':
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device = optarg;
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break;
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case 'P':
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strncpy(password, optarg, 32);
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password[32] = 0;
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break;
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default:
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usage();
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/* NOTREACHED */
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}
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}
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if (geteuid() != 0) {
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printf("Run as root and you'll be happy.\n");
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usage();
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}
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|
|
argc -= optind;
|
|
argv += optind;
|
|
|
|
if (argc != 2)
|
|
usage();
|
|
|
|
topdomain = strdup(argv[1]);
|
|
|
|
if(username) {
|
|
pw = getpwnam(username);
|
|
if (!pw) {
|
|
printf("User %s does not exist!\n", username);
|
|
usage();
|
|
}
|
|
}
|
|
|
|
if (strlen(password) == 0) {
|
|
printf("Enter password on stdin:\n");
|
|
scanf("%32s", password);
|
|
password[32] = 0;
|
|
}
|
|
|
|
if ((tun_fd = open_tun(device)) == -1)
|
|
goto cleanup1;
|
|
if ((dns_fd = open_dns(0, INADDR_ANY)) == -1)
|
|
goto cleanup2;
|
|
set_target(argv[0]);
|
|
|
|
signal(SIGINT, sighandler);
|
|
signal(SIGTERM, sighandler);
|
|
|
|
if(handshake(dns_fd))
|
|
goto cleanup2;
|
|
|
|
printf("Sending queries for %s to %s\n", argv[1], argv[0]);
|
|
|
|
do_chroot(newroot);
|
|
|
|
if (username) {
|
|
if (setgid(pw->pw_gid) < 0 || setuid(pw->pw_uid) < 0) {
|
|
printf("Could not switch to user %s!\n", username);
|
|
usage();
|
|
}
|
|
}
|
|
|
|
if (!foreground) {
|
|
do_detach();
|
|
}
|
|
|
|
tunnel(tun_fd, dns_fd);
|
|
|
|
cleanup2:
|
|
close_dns(dns_fd);
|
|
close_tun(tun_fd);
|
|
cleanup1:
|
|
|
|
return 0;
|
|
}
|