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iodine/src/iodined.c

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/*
* Copyright (c) 2006-2009 Bjorn Andersson <flex@kryo.se>, Erik Ekman <yarrick@kryo.se>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/time.h>
#define _XPG4_2
#include <sys/socket.h>
#include <sys/uio.h>
#include <fcntl.h>
#include <err.h>
#include <grp.h>
#include <time.h>
#include <pwd.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <zlib.h>
#include <arpa/nameser.h>
#ifdef DARWIN
#include <arpa/nameser8_compat.h>
#endif
#include "common.h"
#include "dns.h"
#include "encoding.h"
#include "base32.h"
#include "base64.h"
#include "user.h"
#include "login.h"
#include "tun.h"
#include "fw_query.h"
#include "version.h"
static int running = 1;
static char *topdomain;
static char password[33];
static struct encoder *b32;
static int created_users;
static int check_ip;
static int my_mtu;
static in_addr_t my_ip;
static int netmask;
static in_addr_t ns_ip;
static int bind_port;
static int debug;
#if !defined(BSD) && !defined(__GLIBC__)
static char *__progname;
#endif
static int read_dns(int, struct query *);
static void write_dns(int, struct query *, char *, int);
static void
sigint(int sig)
{
running = 0;
}
static int
ip_cmp(int userid, struct query *q)
{
struct sockaddr_in *tempin;
tempin = (struct sockaddr_in *) &(q->from);
return memcmp(&(users[userid].host), &(tempin->sin_addr), sizeof(struct in_addr));
}
static int
tunnel_tun(int tun_fd, int dns_fd)
{
unsigned long outlen;
struct ip *header;
char out[64*1024];
char in[64*1024];
int userid;
int read;
if ((read = read_tun(tun_fd, in, sizeof(in))) <= 0)
return 0;
/* find target ip in packet, in is padded with 4 bytes TUN header */
header = (struct ip*) (in + 4);
userid = find_user_by_ip(header->ip_dst.s_addr);
if (userid < 0)
return 0;
outlen = sizeof(out);
compress2((uint8_t*)out, &outlen, (uint8_t*)in, read, 9);
/* if another packet is queued, throw away this one. TODO build queue */
if (users[userid].outpacket.len == 0) {
memcpy(users[userid].outpacket.data, out, outlen);
users[userid].outpacket.len = outlen;
users[userid].outpacket.seqno++;
users[userid].outpacket.fragment = 0;
return outlen;
} else {
return 0;
}
}
typedef enum {
VERSION_ACK,
VERSION_NACK,
VERSION_FULL
} version_ack_t;
static void
send_version_response(int fd, version_ack_t ack, uint32_t payload, int userid, struct query *q)
{
char out[9];
switch (ack) {
case VERSION_ACK:
strncpy(out, "VACK", sizeof(out));
break;
case VERSION_NACK:
strncpy(out, "VNAK", sizeof(out));
break;
case VERSION_FULL:
strncpy(out, "VFUL", sizeof(out));
break;
}
out[4] = ((payload >> 24) & 0xff);
out[5] = ((payload >> 16) & 0xff);
out[6] = ((payload >> 8) & 0xff);
out[7] = ((payload) & 0xff);
out[8] = userid & 0xff;
write_dns(fd, q, out, sizeof(out));
}
static void
update_downstream_seqno(int dns_fd, int userid, int down_seq, int down_frag)
{
/* update outgoing seqno/frag */
if (down_seq != users[userid].out_acked_seqno) {
/* First ack on new outgoing packet */
users[userid].out_acked_seqno = down_seq;
users[userid].out_acked_fragment = down_frag;
} else {
if (down_frag > users[userid].out_acked_fragment) {
/* Ack on later fragment */
users[userid].out_acked_fragment = down_frag;
}
}
/* Send reply if waiting */
if (users[userid].outpacket.len > 0) {
if (debug >= 1) {
printf("OUT pkt seq# %d, frag %d (last=%d), fragsize %d, total %d, to user %d\n",
users[userid].outpacket.seqno & 7, users[userid].outpacket.fragment & 15,
1, users[userid].outpacket.len, users[userid].outpacket.len, userid);
}
write_dns(dns_fd, &users[userid].q, users[userid].outpacket.data, users[userid].outpacket.len);
users[userid].outpacket.len = 0;
users[userid].q.id = 0;
}
}
static void
handle_null_request(int tun_fd, int dns_fd, struct query *q, int domain_len)
{
struct in_addr tempip;
struct ip *hdr;
unsigned long outlen;
char in[512];
char logindata[16];
char out[64*1024];
char unpacked[64*1024];
char *tmp[2];
int userid;
int touser;
int version;
int code;
int read;
userid = -1;
memcpy(in, q->name, MIN(domain_len, sizeof(in)));
if(in[0] == 'V' || in[0] == 'v') {
read = unpack_data(unpacked, sizeof(unpacked), &(in[1]), domain_len - 1, b32);
/* Version greeting, compare and send ack/nak */
if (read > 4) {
/* Received V + 32bits version */
version = (((unpacked[0] & 0xff) << 24) |
((unpacked[1] & 0xff) << 16) |
((unpacked[2] & 0xff) << 8) |
((unpacked[3] & 0xff)));
}
if (version == VERSION) {
userid = find_available_user();
if (userid >= 0) {
struct sockaddr_in *tempin;
users[userid].seed = rand();
/* Store remote IP number */
tempin = (struct sockaddr_in *) &(q->from);
memcpy(&(users[userid].host), &(tempin->sin_addr), sizeof(struct in_addr));
memcpy(&(users[userid].q), q, sizeof(struct query));
users[userid].encoder = get_base32_encoder();
send_version_response(dns_fd, VERSION_ACK, users[userid].seed, userid, q);
users[userid].q.id = 0;
} else {
/* No space for another user */
send_version_response(dns_fd, VERSION_FULL, created_users, 0, q);
}
} else {
send_version_response(dns_fd, VERSION_NACK, VERSION, 0, q);
}
return;
} else if(in[0] == 'L' || in[0] == 'l') {
read = unpack_data(unpacked, sizeof(unpacked), &(in[1]), domain_len - 1, b32);
/* Login phase, handle auth */
userid = unpacked[0];
if (userid < 0 || userid >= USERS) {
write_dns(dns_fd, q, "BADIP", 5);
return; /* illegal id */
}
users[userid].last_pkt = time(NULL);
login_calculate(logindata, 16, password, users[userid].seed);
if (check_ip && ip_cmp(userid, q) != 0) {
write_dns(dns_fd, q, "BADIP", 5);
} else {
if (read >= 18 && (memcmp(logindata, unpacked+1, 16) == 0)) {
/* Login ok, send ip/mtu/netmask info */
tempip.s_addr = my_ip;
tmp[0] = strdup(inet_ntoa(tempip));
tempip.s_addr = users[userid].tun_ip;
tmp[1] = strdup(inet_ntoa(tempip));
read = snprintf(out, sizeof(out), "%s-%s-%d-%d",
tmp[0], tmp[1], my_mtu, netmask);
write_dns(dns_fd, q, out, read);
q->id = 0;
free(tmp[1]);
free(tmp[0]);
} else {
write_dns(dns_fd, q, "LNAK", 4);
}
}
return;
} else if(in[0] == 'Z' || in[0] == 'z') {
/* Check for case conservation and chars not allowed according to RFC */
/* Reply with received hostname as data */
write_dns(dns_fd, q, in, domain_len);
return;
} else if(in[0] == 'S' || in[0] == 's') {
int codec;
struct encoder *enc;
if (domain_len != 4) { /* len = 4, example: "S15." */
write_dns(dns_fd, q, "BADLEN", 6);
return;
}
userid = b32_8to5(in[1]);
if (ip_cmp(userid, q) != 0) {
write_dns(dns_fd, q, "BADIP", 5);
return; /* illegal id */
}
codec = b32_8to5(in[2]);
switch (codec) {
case 5: /* 5 bits per byte = base32 */
enc = get_base32_encoder();
user_switch_codec(userid, enc);
write_dns(dns_fd, q, enc->name, strlen(enc->name));
break;
case 6: /* 6 bits per byte = base64 */
enc = get_base64_encoder();
user_switch_codec(userid, enc);
write_dns(dns_fd, q, enc->name, strlen(enc->name));
break;
default:
write_dns(dns_fd, q, "BADCODEC", 8);
break;
}
return;
} else if(in[0] == 'P' || in[0] == 'p') {
int dn_seq;
int dn_frag;
read = unpack_data(unpacked, sizeof(unpacked), &(in[1]), domain_len - 1, b32);
/* Ping packet, store userid */
userid = unpacked[0];
if (userid < 0 || userid >= USERS || ip_cmp(userid, q) != 0) {
write_dns(dns_fd, q, "BADIP", 5);
return; /* illegal id */
}
dn_seq = unpacked[1] >> 4;
dn_frag = unpacked[1] & 15;
memcpy(&(users[userid].q), q, sizeof(struct query));
users[userid].last_pkt = time(NULL);
/* Update seqno and maybe send immediate response packet */
update_downstream_seqno(dns_fd, userid, dn_seq, dn_frag);
} else if((in[0] >= '0' && in[0] <= '9')
|| (in[0] >= 'a' && in[0] <= 'f')
|| (in[0] >= 'A' && in[0] <= 'F')) {
if ((in[0] >= '0' && in[0] <= '9'))
code = in[0] - '0';
if ((in[0] >= 'a' && in[0] <= 'f'))
code = in[0] - 'a' + 10;
if ((in[0] >= 'A' && in[0] <= 'F'))
code = in[0] - 'A' + 10;
userid = code;
if (userid < 0 || userid >= USERS) {
write_dns(dns_fd, q, "BADIP", 5);
return; /* illegal id */
}
/* Check sending ip number */
if (check_ip && ip_cmp(userid, q) != 0) {
write_dns(dns_fd, q, "BADIP", 5);
} else {
/* Decode data header */
int up_seq = (b32_8to5(in[1]) >> 2) & 7;
int up_frag = ((b32_8to5(in[1]) & 3) << 2) | ((b32_8to5(in[2]) >> 3) & 3);
int dn_seq = (b32_8to5(in[2]) & 7);
int dn_frag = b32_8to5(in[3]) >> 1;
int lastfrag = b32_8to5(in[3]) & 1;
/* Update query and time info for user */
users[userid].last_pkt = time(NULL);
memcpy(&(users[userid].q), q, sizeof(struct query));
if (up_seq == users[userid].inpacket.seqno &&
up_frag <= users[userid].inpacket.fragment) {
/* Got repeated old packet, skip it */
if (debug >= 1) {
printf("IN pkt seq# %d, frag %d, dropped duplicate\n",
up_seq, up_frag);
}
/* Update seqno and maybe send immediate response packet */
update_downstream_seqno(dns_fd, userid, dn_seq, dn_frag);
return;
}
if (up_seq != users[userid].inpacket.seqno) {
/* New packet has arrived */
users[userid].inpacket.seqno = up_seq;
users[userid].inpacket.len = 0;
users[userid].inpacket.offset = 0;
}
users[userid].inpacket.fragment = up_frag;
/* decode with this users encoding */
read = unpack_data(unpacked, sizeof(unpacked), &(in[4]), domain_len - 4,
users[userid].encoder);
/* copy to packet buffer, update length */
memcpy(users[userid].inpacket.data + users[userid].inpacket.offset, unpacked, read);
users[userid].inpacket.len += read;
users[userid].inpacket.offset += read;
if (debug >= 1) {
printf("IN pkt seq# %d, frag %d (last=%d), fragsize %d, total %d, from user %d\n",
up_seq, up_frag, lastfrag, read, users[userid].inpacket.len, userid);
}
if (lastfrag & 1) { /* packet is complete */
int ret;
outlen = sizeof(out);
ret = uncompress((uint8_t*)out, &outlen,
(uint8_t*)users[userid].inpacket.data, users[userid].inpacket.len);
if (ret == Z_OK) {
hdr = (struct ip*) (out + 4);
touser = find_user_by_ip(hdr->ip_dst.s_addr);
if (touser == -1) {
/* send the uncompressed packet to tun device */
write_tun(tun_fd, out, outlen);
} else {
/* send the compressed packet to other client
* if another packet is queued, throw away this one. TODO build queue */
if (users[touser].outpacket.len == 0) {
memcpy(users[touser].outpacket.data, users[userid].inpacket.data, users[userid].inpacket.len);
users[touser].outpacket.len = users[userid].inpacket.len;
}
}
} else {
printf("Discarded data, uncompress() result: %d\n", ret);
}
users[userid].inpacket.len = users[userid].inpacket.offset = 0;
}
/* Update seqno and maybe send immediate response packet */
update_downstream_seqno(dns_fd, userid, dn_seq, dn_frag);
}
}
}
static void
handle_ns_request(int dns_fd, struct query *q)
{
char buf[64*1024];
int len;
if (ns_ip != INADDR_ANY) {
memcpy(&q->destination.s_addr, &ns_ip, sizeof(in_addr_t));
}
len = dns_encode_ns_response(buf, sizeof(buf), q, topdomain);
if (debug >= 2) {
struct sockaddr_in *tempin;
tempin = (struct sockaddr_in *) &(q->from);
printf("TX: client %s, type %d, name %s, %d bytes NS reply\n",
inet_ntoa(tempin->sin_addr), q->type, q->name, len);
}
if (sendto(dns_fd, buf, len, 0, (struct sockaddr*)&q->from, q->fromlen) <= 0) {
warn("ns reply send error");
}
}
static void
forward_query(int bind_fd, struct query *q)
{
char buf[64*1024];
int len;
struct fw_query fwq;
struct sockaddr_in *myaddr;
in_addr_t newaddr;
len = dns_encode(buf, sizeof(buf), q, QR_QUERY, q->name, strlen(q->name));
/* Store sockaddr for q->id */
memcpy(&(fwq.addr), &(q->from), q->fromlen);
fwq.addrlen = q->fromlen;
fwq.id = q->id;
fw_query_put(&fwq);
newaddr = inet_addr("127.0.0.1");
myaddr = (struct sockaddr_in *) &(q->from);
memcpy(&(myaddr->sin_addr), &newaddr, sizeof(in_addr_t));
myaddr->sin_port = htons(bind_port);
if (debug >= 2) {
printf("TX: NS reply \n");
}
if (sendto(bind_fd, buf, len, 0, (struct sockaddr*)&q->from, q->fromlen) <= 0) {
warn("forward query error");
}
}
static int
tunnel_bind(int bind_fd, int dns_fd)
{
char packet[64*1024];
struct sockaddr_in from;
socklen_t fromlen;
struct fw_query *query;
short id;
int r;
fromlen = sizeof(struct sockaddr);
r = recvfrom(bind_fd, packet, sizeof(packet), 0,
(struct sockaddr*)&from, &fromlen);
if (r <= 0)
return 0;
id = dns_get_id(packet, r);
if (debug >= 2) {
printf("RX: Got response on query %u from DNS\n", (id & 0xFFFF));
}
/* Get sockaddr from id */
fw_query_get(id, &query);
if (!query && debug >= 2) {
printf("Lost sender of id %u, dropping reply\n", (id & 0xFFFF));
return 0;
}
if (debug >= 2) {
struct sockaddr_in *in;
in = (struct sockaddr_in *) &(query->addr);
printf("TX: client %s id %u, %d bytes\n",
inet_ntoa(in->sin_addr), (id & 0xffff), r);
}
if (sendto(dns_fd, packet, r, 0, (const struct sockaddr *) &(query->addr),
query->addrlen) <= 0) {
warn("forward reply error");
}
return 0;
}
static int
tunnel_dns(int tun_fd, int dns_fd, int bind_fd)
{
struct query q;
int read;
char *domain;
int domain_len;
int inside_topdomain;
if ((read = read_dns(dns_fd, &q)) <= 0)
return 0;
if (debug >= 2) {
struct sockaddr_in *tempin;
tempin = (struct sockaddr_in *) &(q.from);
printf("RX: client %s, type %d, name %s\n",
inet_ntoa(tempin->sin_addr), q.type, q.name);
}
domain = strstr(q.name, topdomain);
inside_topdomain = 0;
if (domain) {
domain_len = (int) (domain - q.name);
if (domain_len + strlen(topdomain) == strlen(q.name)) {
inside_topdomain = 1;
}
}
if (inside_topdomain) {
/* This is a query we can handle */
switch (q.type) {
case T_NULL:
handle_null_request(tun_fd, dns_fd, &q, domain_len);
break;
case T_NS:
handle_ns_request(dns_fd, &q);
break;
default:
break;
}
} else {
/* Forward query to other port ? */
if (bind_fd) {
forward_query(bind_fd, &q);
}
}
return 0;
}
static int
tunnel(int tun_fd, int dns_fd, int bind_fd)
{
struct timeval tv;
fd_set fds;
int i;
while (running) {
int maxfd;
if (users_waiting_on_reply()) {
tv.tv_sec = 0;
tv.tv_usec = 15000;
} else {
tv.tv_sec = 1;
tv.tv_usec = 0;
}
FD_ZERO(&fds);
FD_SET(dns_fd, &fds);
maxfd = dns_fd;
if (bind_fd) {
/* wait for replies from real DNS */
FD_SET(bind_fd, &fds);
maxfd = MAX(bind_fd, maxfd);
}
/* TODO : use some kind of packet queue */
if(!all_users_waiting_to_send()) {
FD_SET(tun_fd, &fds);
maxfd = MAX(tun_fd, maxfd);
}
i = select(maxfd + 1, &fds, NULL, NULL, &tv);
if(i < 0) {
if (running)
warn("select");
return 1;
}
if (i==0) {
int j;
for (j = 0; j < USERS; j++) {
if (users[j].q.id != 0) {
if (debug >= 1 && users[j].outpacket.len > 0) {
printf("OUT pkt seq# %d, frag %d (last=%d), "
"fragsize %d of total %d, to user %d\n",
users[j].outpacket.seqno & 7,
users[j].outpacket.fragment & 15, 1,
users[j].outpacket.len, users[j].outpacket.len, j);
}
write_dns(dns_fd, &(users[j].q), users[j].outpacket.data, users[j].outpacket.len);
users[j].outpacket.len = 0;
users[j].q.id = 0;
}
}
} else {
if(FD_ISSET(tun_fd, &fds)) {
tunnel_tun(tun_fd, dns_fd);
continue;
}
if(FD_ISSET(dns_fd, &fds)) {
tunnel_dns(tun_fd, dns_fd, bind_fd);
continue;
}
if(FD_ISSET(bind_fd, &fds)) {
tunnel_bind(bind_fd, dns_fd);
continue;
}
}
}
return 0;
}
static int
read_dns(int fd, struct query *q)
{
struct sockaddr_in from;
socklen_t addrlen;
char packet[64*1024];
char address[96];
struct msghdr msg;
struct iovec iov;
struct cmsghdr *cmsg;
int r;
addrlen = sizeof(struct sockaddr);
iov.iov_base = packet;
iov.iov_len = sizeof(packet);
msg.msg_name = (caddr_t) &from;
msg.msg_namelen = (unsigned) addrlen;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = address;
msg.msg_controllen = sizeof(address);
msg.msg_flags = 0;
r = recvmsg(fd, &msg, 0);
if (r > 0) {
dns_decode(NULL, 0, q, QR_QUERY, packet, r);
memcpy((struct sockaddr*)&q->from, (struct sockaddr*)&from, addrlen);
q->fromlen = addrlen;
for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
cmsg = CMSG_NXTHDR(&msg, cmsg)) {
if (cmsg->cmsg_level == IPPROTO_IP &&
cmsg->cmsg_type == DSTADDR_SOCKOPT) {
q->destination = *dstaddr(cmsg);
break;
}
}
return strlen(q->name);
} else if (r < 0) {
/* Error */
warn("read dns");
}
return 0;
}
static void
write_dns(int fd, struct query *q, char *data, int datalen)
{
char buf[64*1024];
int len;
len = dns_encode(buf, sizeof(buf), q, QR_ANSWER, data, datalen);
if (debug >= 2) {
struct sockaddr_in *tempin;
tempin = (struct sockaddr_in *) &(q->from);
printf("TX: client %s, type %d, name %s, %d bytes data\n",
inet_ntoa(tempin->sin_addr), q->type, q->name, datalen);
}
sendto(fd, buf, len, 0, (struct sockaddr*)&q->from, q->fromlen);
}
static void
usage() {
extern char *__progname;
printf("Usage: %s [-v] [-h] [-c] [-s] [-f] [-D] [-u user] "
"[-t chrootdir] [-d device] [-m mtu] "
"[-l ip address to listen on] [-p port] [-n external ip] [-b dnsport] [-P password]"
" tunnel_ip[/netmask] topdomain\n", __progname);
exit(2);
}
static void
help() {
extern char *__progname;
printf("iodine IP over DNS tunneling server\n");
printf("Usage: %s [-v] [-h] [-c] [-s] [-f] [-D] [-u user] "
"[-t chrootdir] [-d device] [-m mtu] "
"[-l ip address to listen on] [-p port] [-n external ip] [-b dnsport] [-P password]"
" tunnel_ip[/netmask] topdomain\n", __progname);
printf(" -v to print version info and exit\n");
printf(" -h to print this help and exit\n");
printf(" -c to disable check of client IP/port on each request\n");
printf(" -s to skip creating and configuring the tun device, "
"which then has to be created manually\n");
printf(" -f to keep running in foreground\n");
printf(" -D to increase debug level\n");
printf(" -u name to drop privileges and run as user 'name'\n");
printf(" -t dir to chroot to directory dir\n");
printf(" -d device to set tunnel device name\n");
printf(" -m mtu to set tunnel device mtu\n");
printf(" -l ip address to listen on for incoming dns traffic "
"(default 0.0.0.0)\n");
printf(" -p port to listen on for incoming dns traffic (default 53)\n");
printf(" -n ip to respond with to NS queries\n");
printf(" -b port to forward normal DNS queries to (on localhost)\n");
printf(" -P password used for authentication (max 32 chars will be used)\n");
printf("tunnel_ip is the IP number of the local tunnel interface.\n");
printf(" /netmask sets the size of the tunnel network.\n");
printf("topdomain is the FQDN that is delegated to this server.\n");
exit(0);
}
static void
version() {
char *svnver;
svnver = "$Rev$ from $Date$";
printf("iodine IP over DNS tunneling server\n");
printf("SVN version: %s\n", svnver);
exit(0);
}
int
main(int argc, char **argv)
{
in_addr_t listen_ip;
struct passwd *pw;
int foreground;
char *username;
char *newroot;
char *device;
int dnsd_fd;
int tun_fd;
/* settings for forwarding normal DNS to
* local real DNS server */
int bind_fd;
int bind_enable;
int choice;
int port;
int mtu;
int skipipconfig;
char *netsize;
username = NULL;
newroot = NULL;
device = NULL;
foreground = 0;
bind_enable = 0;
bind_fd = 0;
mtu = 1024;
listen_ip = INADDR_ANY;
port = 53;
ns_ip = INADDR_ANY;
check_ip = 1;
skipipconfig = 0;
debug = 0;
netmask = 27;
b32 = get_base32_encoder();
#if !defined(BSD) && !defined(__GLIBC__)
__progname = strrchr(argv[0], '/');
if (__progname == NULL)
__progname = argv[0];
else
__progname++;
#endif
memset(password, 0, sizeof(password));
srand(time(NULL));
fw_query_init();
while ((choice = getopt(argc, argv, "vcsfhDu:t:d:m:l:p:n:b:P:")) != -1) {
switch(choice) {
case 'v':
version();
break;
case 'c':
check_ip = 0;
break;
case 's':
skipipconfig = 1;
break;
case 'f':
foreground = 1;
break;
case 'h':
help();
break;
case 'D':
debug++;
break;
case 'u':
username = optarg;
break;
case 't':
newroot = optarg;
break;
case 'd':
device = optarg;
break;
case 'm':
mtu = atoi(optarg);
break;
case 'l':
listen_ip = inet_addr(optarg);
break;
case 'p':
port = atoi(optarg);
break;
case 'n':
ns_ip = inet_addr(optarg);
break;
case 'b':
bind_enable = 1;
bind_port = atoi(optarg);
break;
case 'P':
strncpy(password, optarg, sizeof(password));
password[sizeof(password)-1] = 0;
/* XXX: find better way of cleaning up ps(1) */
memset(optarg, 0, strlen(optarg));
break;
default:
usage();
break;
}
}
argc -= optind;
argv += optind;
if (geteuid() != 0) {
warnx("Run as root and you'll be happy.\n");
usage();
}
if (argc != 2)
usage();
netsize = strchr(argv[0], '/');
if (netsize) {
*netsize = 0;
netsize++;
netmask = atoi(netsize);
}
my_ip = inet_addr(argv[0]);
if (my_ip == INADDR_NONE) {
warnx("Bad IP address to use inside tunnel.\n");
usage();
}
topdomain = strdup(argv[1]);
if(strlen(topdomain) <= 128) {
if(check_topdomain(topdomain)) {
warnx("Topdomain contains invalid characters.\n");
usage();
}
} else {
warnx("Use a topdomain max 128 chars long.\n");
usage();
}
if (username != NULL) {
if ((pw = getpwnam(username)) == NULL) {
warnx("User %s does not exist!\n", username);
usage();
}
}
if (mtu <= 0) {
warnx("Bad MTU given.\n");
usage();
}
if(port < 1 || port > 65535) {
warnx("Bad port number given.\n");
usage();
}
if(bind_enable) {
if (bind_port < 1 || bind_port > 65535 || bind_port == port) {
warnx("Bad DNS server port number given.\n");
usage();
/* NOTREACHED */
}
printf("Requests for domains outside of %s will be forwarded to port %d\n",
topdomain, bind_port);
}
if (port != 53) {
printf("ALERT! Other dns servers expect you to run on port 53.\n");
printf("You must manually forward port 53 to port %d for things to work.\n", port);
}
if (debug) {
printf("Debug level %d enabled, will stay in foreground.\n", debug);
printf("Add more -D switches to set higher debug level.\n");
foreground = 1;
}
if (listen_ip == INADDR_NONE) {
warnx("Bad IP address to listen on.\n");
usage();
}
if (ns_ip == INADDR_NONE) {
warnx("Bad IP address to return as nameserver.\n");
usage();
}
if (netmask > 30 || netmask < 8) {
warnx("Bad netmask (%d bits). Use 8-30 bits.\n", netmask);
usage();
}
if (strlen(password) == 0)
read_password(password, sizeof(password));
if ((tun_fd = open_tun(device)) == -1)
goto cleanup0;
if (!skipipconfig)
if (tun_setip(argv[0], netmask) != 0 || tun_setmtu(mtu) != 0)
goto cleanup1;
if ((dnsd_fd = open_dns(port, listen_ip)) == -1)
goto cleanup2;
if (bind_enable)
if ((bind_fd = open_dns(0, INADDR_ANY)) == -1)
goto cleanup3;
my_mtu = mtu;
created_users = init_users(my_ip, netmask);
if (created_users < USERS) {
printf("Limiting to %d simultaneous users because of netmask /%d\n",
created_users, netmask);
}
printf("Listening to dns for domain %s\n", topdomain);
if (foreground == 0)
do_detach();
if (newroot != NULL)
do_chroot(newroot);
signal(SIGINT, sigint);
if (username != NULL) {
gid_t gids[1];
gids[0] = pw->pw_gid;
if (setgroups(1, gids) < 0 || setgid(pw->pw_gid) < 0 || setuid(pw->pw_uid) < 0) {
warnx("Could not switch to user %s!\n", username);
usage();
}
}
tunnel(tun_fd, dnsd_fd, bind_fd);
cleanup3:
close_dns(bind_fd);
cleanup2:
close_dns(dnsd_fd);
cleanup1:
close_tun(tun_fd);
cleanup0:
return 0;
}
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