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ttdnsd.c
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ttdnsd.c
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/*
* The Tor TCP DNS Daemon
*
* Copyright (c) Collin R. Mulliner <collin(AT)mulliner.org>
* Copyright (c) 2010, The Tor Project, Inc.
*
* http://www.mulliner.org/collin/ttdnsd.php
* https://www.torproject.org/ttdnsd/
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <getopt.h>
#include <time.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/poll.h>
#include <netinet/in.h>
#include <netdb.h>
#include <net/if.h>
#include <arpa/inet.h>
#include <limits.h>
#include "ttdnsd.h"
/*
* Binary is linked with libtsocks therefore all TCP connections will
* be routed over Tor (if tsocks.conf is set up to chain with Tor).
*
* See Makefile about disabling tsocks (for testing).
*
*/
static struct in_addr *nameservers; /**< nameservers pool */
static unsigned int num_nameservers; /**< number of nameservers */
static struct peer_t peers[MAX_PEERS]; /**< TCP peers */
static struct request_t requests[MAX_REQUESTS]; /**< request queue */
static int udp_fd; /**< port 53 socket */
/*
Someday:
static int multipeer = 0;
static int multireq = 0;
*/
/* Return a positive positional number or -1 for unfound entries. */
int request_find(uint id)
{
uint pos = id % MAX_REQUESTS;
for (;;) {
if (requests[pos].id == id) {
printf("found id=%d at pos=%d\n", id, pos);
return pos;
}
else {
pos++;
pos %= MAX_REQUESTS;
if (pos == (id % MAX_REQUESTS)) {
printf("can't find id=%d\n", id);
return -1;
}
}
}
}
/* Returns a display name for the peer; currently inet_ntoa, so
statically allocated */
static const char *peer_display(struct peer_t *p)
{
return inet_ntoa(p->tcp.sin_addr);
}
/* Returns 1 upon non-blocking connection setup; 0 upon serious error */
int peer_connect(struct peer_t *p, struct in_addr ns)
{
int socket_opt_val = 1;
int cs;
unsigned char message[1000];
unsigned char server_reply[2000];
int port=53;
char *host;
char length[2];
char portC[2];
int res;
if (p->con == CONNECTING || p->con == CONNECTING2) {
printf("It appears that peer %s is already CONNECTING\n",
peer_display(p));
return 1;
}
if ((p->tcp_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
printf("Can't create TCP socket\n");
return 0;
}
p->tcp.sin_family = AF_INET;
// This should not be hardcoded to a magic number;
// per ns port data structure changes required
p->tcp.sin_port = htons(9050);
p->tcp.sin_addr.s_addr = inet_addr("127.0.0.1");
printf("--------------- New connection -----------------\n");
printf("connecting to %s on port %i\n", peer_display(p), ntohs(p->tcp.sin_port));
cs = connect(p->tcp_fd, (struct sockaddr*)&(p->tcp), sizeof(p->tcp));
if (cs<0)
{
puts("error");
return 0;
}
else
puts("Connected\n");
/*
* Initialise connection with socks5
*
*/
message[0]=5;
message[1]=1;
message[2]=0;
message[3]='\0';
//Sending identification data to socks5 proxy
if( send(p->tcp_fd , message , 3 , 0) < 0) {
puts("Send failed");
return 1;
}
//Receive a reply from the server
if( recv(p->tcp_fd , server_reply , 2000 , 0) < 0) {
puts("recv failed");
return 0;
}
message[0]=5;
message[1]=1;
message[2]=0;
message[3]=3;
/*
* Asking socks5 to connect to a specific DNS resolver
*
*/
host=inet_ntoa(ns);
printf("Host: %s\n",host);
length[0]= strlen(host);
length[1]= 0;
portC[1]=port%256;
portC[0]=port/256;
//Send initial message
if( send(p->tcp_fd , message , 4 , 0) < 0) {
puts("Send failed");
return 1;
}
//Send hsotname lenth
if( send(p->tcp_fd, length , 1 , 0) < 0) {
puts("Send failed");
return 1;
}
//Send hostname
if( send(p->tcp_fd , host , strlen(host) , 0) < 0) {
puts("Send failed");
return 1;
}
//sendport
if( send(p->tcp_fd , portC , 2 , 0) < 0) {
puts("Send failed");
return 1;
}
//Receive a reply from the server
if( (res=recv(p->tcp_fd , server_reply ,200 , 0)) < 0)
{
puts("recv failed");
return 0;
}
if (cs != 0 && errno != EINPROGRESS) {
perror("connect status");
return 0;
}
if (setsockopt(p->tcp_fd, SOL_SOCKET, SO_REUSEADDR, &socket_opt_val, sizeof(int)))
printf("Setting SO_REUSEADDR failed\n");
if (fcntl(p->tcp_fd, F_SETFL, O_NONBLOCK))
printf("Setting O_NONBLOCK failed\n");
//We should be in non-blocking mode now
p->bl = 0;
p->con = CONNECTING;
return 1;
}
/* Returns 1 upon non-blocking connection; 0 upon serious error */
int peer_connected(struct peer_t *p)
{
int cs;
// /* QUASIBUG This is not documented as a correct way to poll for
// connection establishment. Linux connect(2) says: “Generally,
// connection-based protocol sockets may successfully connect()
// only once...It is possible to select(2) or poll(2) for
// completion by selecting the socket for writing. After
// select(2) indicates writability, use getsockopt(2) to read the
// SO_ERROR option at level SOL_SOCKET to determine whether
// connect() completed successfully (SO_ERROR is zero) or
// unsuccessfully (SO_ERROR is one of the usual error codes listed
// here, explaining the reason for the failure).”
//
// If this works the way it’s documented to work, we should just
// use the documented interface.
// */
//
int error_code;
socklen_t error_code_size = sizeof(error_code);
getsockopt(p->tcp_fd, SOL_SOCKET, SO_ERROR, &error_code, &error_code_size);
if (error_code == 0) {
p->con = CONNECTED;
return 1;
} else {
printf("connection failed with code:%d\n",error_code);
printf("Is Tor running?\n");
close(p->tcp_fd);
p->tcp_fd = -1;
p->con = DEAD;
return 0;
}
printf("%s %d",peer_display(p),cs);
return 1;
}
/*
int peer_keepalive(uint peer)
{
return 1;
}
*/
static void peer_mark_as_dead(struct peer_t *p)
{
close(p->tcp_fd);
p->tcp_fd = -1;
p->con = DEAD;
printf("peer %s got disconnected\n", peer_display(p));
}
/* Returns 1 upon sent request; 0 upon serious error and 2 upon disconnect */
int peer_sendreq(struct peer_t *p, struct request_t *r)
{
int ret;
r->active = SENT; /* BUG: even if the write below fails? */
/* QUASIBUG Busy-waiting on the network buffer to free up some
space is not acceptable; at best, it wastes CPU; at worst, it
hangs the daemon until the TCP timeout informs it that its
connection to Tor has timed out. (Although that’s an unlikely
failure mode.) */
/* BUG: what if write() doesn't write all the data? */
/* This is writing data to the remote DNS server over Tor with TCP */
while ((ret = write(p->tcp_fd, r->b, (r->bl + 2))) < 0 && errno == EAGAIN);
printf("peer_sendreq write attempt returned: %d\n", ret);
if (ret == 0) {
peer_mark_as_dead(p);
return 2;
}
return 1;
}
/* Returns -1 on error, returns 1 on something, returns 2 on something, returns 3 on disconnect. */
/* XXX This function needs a really serious re-write/audit/etc. */
int peer_readres(struct peer_t *p)
{
struct request_t *r;
int ret;
unsigned short int *ul;
int id;
int req;
unsigned short int *l;
int len;
l = (unsigned short int*)p->b;
/* BUG: we’re reading on a TCP socket here, so we could in theory
get a partial response. Using TCP puts the onus on the user
program (i.e. this code) to buffer bytes until we have a
parseable response. This probably won’t happen very often in
practice because even with DF, the path MTU is unlikely to be
smaller than the DNS response. But it could happen. And then
we fall into the `processanswer` code below without having the
whole answer. */
/* This is reading data from Tor over TCP */
while ((ret = read(p->tcp_fd, (p->b + p->bl), (RECV_BUF_SIZE - p->bl))) < 0 && errno == EAGAIN);
printf("peer_readres read attempt returned: %d\n", ret);
if (ret == 0) {
peer_mark_as_dead(p);
return 3;
}
p->bl += ret;
// get answer from receive buffer
do {
if (p->bl < 2) {
return 2;
}
else {
len = ntohs(*l);
printf("r l=%d r=%d\n", len, p->bl-2);
if ((len + 2) > p->bl)
return 2;
}
printf("received answer %d bytes\n", p->bl);
ul = (unsigned short int*)(p->b + 2);
id = ntohs(*ul);
if ((req = request_find(id)) == -1) {
memmove(p->b, (p->b + len + 2), (p->bl - len - 2));
p->bl -= len + 2;
return 0;
}
r = &requests[req];
// write back real id
*ul = htons(r->rid);
// Remove the AD flag from the reply if it has one. Because we might be
// answering requests to 127.0.0.1, the client might consider us
// trusted. While trusted, we shouldn't indicate that data is DNSSEC
// valid when we haven't checked it.
// See http://tools.ietf.org/html/rfc2535#section-6.1
if (len >= 6)
p->b[5] &= 0xdf;
/* This is where we send the answer over UDP to the client */
r->a.sin_family = AF_INET;
while (sendto(udp_fd, (p->b + 2), len, 0, (struct sockaddr*)&r->a, sizeof(struct sockaddr_in)) < 0 && errno == EAGAIN);
printf("forwarding answer (%d bytes)\n", len);
memmove(p->b, p->b + len +2, p->bl - len - 2);
p->bl -= len + 2;
// mark as handled/unused
r->id = 0;
} while (p->bl > 0);
return 1;
}
/* Handles outstanding peer requests and does not return anything. */
void peer_handleoutstanding(struct peer_t *p)
{
int i;
int ret;
/* QUASIBUG It doesn’t make sense that sometimes `request_add`
will queue up a request to be sent to nameserver #2 when a
connection is already open to nameserver #1, but then send that
request to nameserver #3 if nameserver #3 happens to finish
opening its connection before nameserver #2. */
for (i = 0; i < MAX_REQUESTS; i++) {
struct request_t *r = &requests[i];
if (r->id != 0 && r->active == WAITING) {
ret = peer_sendreq(p, r);
printf("peer_sendreq returned %d\n", ret);
}
}
}
/* Currently, we only return the 0th peer. Someday we might want more? */
/* REFACTOR if we aren't going to round-robin among the peers, we
should remove all the complexity having to do with having more than
one peer. */
struct peer_t *peer_select(void)
{
return &peers[0];
}
/* Selects a random nameserver from the pool and returns the number. */
struct in_addr ns_select(void)
{
// This could use a real bit of randomness, I suspect
return nameservers[(rand()>>16) % num_nameservers];
}
/* Return 0 for a request that is pending or if all slots are full, otherwise
return the value of peer_sendreq or peer_connect respectively... */
int request_add(struct request_t *r)
{
uint pos = r->id % MAX_REQUESTS; // XXX r->id is unchecked
struct peer_t *dst_peer;
unsigned short int *ul;
time_t ct = time(NULL);
struct request_t *req_in_table = 0;
printf("adding new request (id=%d)\n", r->id);
for (;;) {
if (requests[pos].id == 0) {
// this one is unused, take it
printf("new request added at pos: %d\n", pos);
req_in_table = &requests[pos];
break;
}
else {
if (requests[pos].id == r->id) {
if (memcmp((char*)&r->a, (char*)&requests[pos].a, sizeof(r->a)) == 0) {
printf("hash position %d already taken by request with same id; dropping it\n", pos);
return 0;
}
else {
printf("hash position %d selected\n", pos);
/* REFACTOR If it’s okay to do this, it would be
simpler to always do it, instead of only on
collisions. Then, if it’s buggy, it’ll show up
consistently in testing. */
do {
r->id = ((rand()>>16) % 0xffff);
} while (r->id < 1);
pos = r->id % MAX_REQUESTS;
printf("NATing id (id was %d now is %d)\n", r->rid, r->id);
continue;
}
}
else if ((requests[pos].timeout + MAX_TIME) > ct) {
// request timed out, take it
printf("taking pos from timed out request\n");
req_in_table = &requests[pos];
break;
}
else {
pos++;
pos %= MAX_REQUESTS;
if (pos == (r->id % MAX_REQUESTS)) {
printf("no more free request slots, wow this is a busy node. dropping request!\n");
return 0;
}
}
}
}
printf("using request slot %d\n", pos); /* REFACTOR: move into loop */
r->timeout = time(NULL); /* REFACTOR not ct? sloppy */
// update id
ul = (unsigned short int*)(r->b + 2);
*ul = htons(r->id);
printf("updating id: %d\n", htons(r->id));
if ( req_in_table == NULL ) {
return -1;
} else {
memcpy((char*)req_in_table, (char*)r, sizeof(*req_in_table));
}
// XXX: nice feature to have: send request to multiple peers for speedup and reliability
printf("selecting peer\n");
dst_peer = peer_select();
printf("peer selected: %d\n", dst_peer->tcp_fd);
if (dst_peer->con == CONNECTED) {
return peer_sendreq(dst_peer, req_in_table);
}
else {
// The request will be sent by peer_handleoutstanding when the
// connection is established. Actually (see QUASIBUG notice
// earlier) when *any* connection is established.
return peer_connect(dst_peer, ns_select());
}
}
static void process_incoming_request(struct request_t *tmp) {
// get request id
unsigned short int *ul = (unsigned short int*) (tmp->b + 2);
tmp->rid = tmp->id = ntohs(*ul);
// get request length
ul = (unsigned short int*)tmp->b;
*ul = htons(tmp->bl);
printf("received request of %d bytes, id = %d\n", tmp->bl, tmp->id);
request_add(tmp); // This should be checked; we're currently ignoring important returns.
}
int server(char *bind_ip, int bind_port)
{
struct sockaddr_in udp;
struct pollfd pfd[MAX_PEERS+1];
int poll2peers[MAX_PEERS];
int fr;
int i;
int pfd_num;
int r;
for (i = 0; i < MAX_PEERS; i++) {
peers[i].tcp_fd = -1;
poll2peers[i] = -1;
peers[i].con = DEAD;
}
memset((char*)requests, 0, sizeof(requests)); // Why not bzero?
// setup listing port - someday we may also want to listen on TCP just for fun
if ((udp_fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
printf("can't create UDP socket\n");
return(-1);
}
memset((char*)&udp, 0, sizeof(struct sockaddr_in)); // bzero love
udp.sin_family = AF_INET;
udp.sin_addr.s_addr = INADDR_ANY;
udp.sin_port = htons(bind_port);
if (!inet_aton(bind_ip, (struct in_addr*)&udp.sin_addr)) {
printf("is not a valid IPv4 address: %s\n", bind_ip);
return(0); // Why is this 0?
}
if (bind(udp_fd, (struct sockaddr*)&udp, sizeof(struct sockaddr_in)) < 0) {
printf("can't bind to %s:%d\n", bind_ip, bind_port);
close(udp_fd);
return(-1); // Perhaps this should be more useful?
}
// drop privileges
if (!DEBUG) {
r = setgid(NOGROUP);
if (r != 0) {
printf("setgid failed!\n");
return(-1);
}
r = setuid(NOBODY);
if (r != 0) {
printf("setuid failed!\n");
return(-1);
}
}
for (;;) {
// populate poll array
for (pfd_num = 1, i = 0; i < MAX_PEERS; i++) {
if (peers[i].tcp_fd != -1) {
pfd[pfd_num].fd = peers[i].tcp_fd;
switch (peers[i].con) {
case CONNECTED:
pfd[pfd_num].events = POLLIN|POLLPRI;
break;
case DEAD:
pfd[pfd_num].events = POLLOUT|POLLERR;
break;
case CONNECTING:
pfd[pfd_num].events = POLLOUT|POLLERR;
break;
case CONNECTING2:
pfd[pfd_num].events = POLLOUT|POLLERR;
break;
default:
pfd[pfd_num].events = POLLOUT|POLLERR;
break;
}
poll2peers[pfd_num-1] = i;
pfd_num++;
}
}
pfd[0].fd = udp_fd;
pfd[0].events = POLLIN|POLLPRI;
printf("watching %d file descriptors\n", pfd_num);
fr = poll(pfd, pfd_num, -1);
printf("%d file descriptors became ready\n", fr);
// handle tcp connections
for (i = 1; i < pfd_num; i++) {
if (pfd[i].fd != -1 && ((pfd[i].revents & POLLIN) == POLLIN ||
(pfd[i].revents & POLLPRI) == POLLPRI || (pfd[i].revents & POLLOUT)
== POLLOUT || (pfd[i].revents & POLLERR) == POLLERR)) {
uint peer = poll2peers[i-1];
struct peer_t *p = &peers[peer];
if (peer > MAX_PEERS) {
printf("Something is wrong! poll2peers[%i] is larger than MAX_PEERS: %i\n", i-1, peer);
} else switch (p->con) {
case CONNECTED:
peer_readres(p);
break;
case CONNECTING:
case CONNECTING2:
if (peer_connected(p)) {
peer_handleoutstanding(p);
}
break;
case DEAD:
default:
printf("peer %s in bad state %i\n", peer_display(p), p->con);
sleep(1);
break;
}
}
}
// handle port 53
if ((pfd[0].revents & POLLIN) == POLLIN || (pfd[0].revents & POLLPRI) == POLLPRI) {
struct request_t tmp;
memset((char*)&tmp, 0, sizeof(struct request_t)); // bzero
tmp.al = sizeof(struct sockaddr_in);
tmp.bl = recvfrom(udp_fd, tmp.b+2, RECV_BUF_SIZE-2, 0,
(struct sockaddr*)&tmp.a, &tmp.al);
if (tmp.bl < 0) {
perror("recvfrom on UDP fd");
} else {
process_incoming_request(&tmp);
}
}
}
}
int load_nameservers(char *filename)
{
FILE *fp;
char line[MAX_LINE_SIZE] = {0};
unsigned long int ns;
char *eolp;
if (!(fp = fopen(filename, "r"))) {
printf("can't open %s\n", filename);
return 0;
}
num_nameservers = 0;
if (!(nameservers = malloc(sizeof(nameservers[0]) * MAX_NAMESERVERS))) {
fclose(fp);
return 0;
}
if (!fp) return 0; /* QUASIBUG can’t happen */
while (fgets(line, MAX_LINE_SIZE, fp)) {
if (line[0] == '#' || line[0] == '\n' || line[0] == ' ') continue;
if ((eolp = strrchr(line, '\n')) != NULL){
*eolp = 0;
}
if (strstr(line, "192.168.") == line) continue;
if (strstr(line, "172.16.") == line) continue;
if (strstr(line, "127.") == line) continue;
if (strstr(line, "10.") == line) continue;
if (inet_pton(AF_INET, line, &ns)) {
if (num_nameservers >= MAX_NAMESERVERS) {
printf("We've loaded %d nameservers; this is our maximum\n", num_nameservers);
break;
}
nameservers[num_nameservers].s_addr = ns;
num_nameservers++;
printf("We've loaded %s as a nameserver.\n", line);
}
else {
printf("%s: is not a valid IPv4 address\n", line);
}
}
fclose(fp);
nameservers = realloc(nameservers, sizeof(unsigned long int) * num_nameservers);
printf("%d nameservers loaded\n", num_nameservers);
return 1;
}
int main(int argc, char **argv)
{
int opt;
int debug = 0;
int dochroot = 1;
char resolvers[250] = {DEFAULT_RESOLVERS};
char bind_ip[250] = {DEFAULT_BIND_IP};
char chroot_dir[PATH_MAX] = {DEFAULT_CHROOT};
char tsocks_conf[PATH_MAX];
int log = 0;
int lfd;
int bind_port = DEFAULT_BIND_PORT;
int devnull;
char pid_file[PATH_MAX] = {0};
FILE *pf;
int r;
char *env_ptr;
while ((opt = getopt(argc, argv, "VlhdcC:b:f:p:P:")) != EOF) {
switch (opt) {
// log debug to file
case 'l':
log = 1;
break;
// debug
case 'd':
debug = 1;
break;
// DON'T chroot
case 'c':
dochroot = 0;
break;
// Chroot directory
case 'C':
strncpy(chroot_dir, optarg, sizeof(chroot_dir)-1);
break;
// PORT
case 'p':
bind_port = atoi(optarg);
if (bind_port < 1) bind_port = DEFAULT_BIND_PORT;
break;
// config file
case 'f':
strncpy(resolvers, optarg, sizeof(resolvers)-1);
break;
// IP
case 'b':
strncpy(bind_ip, optarg, sizeof(bind_ip)-1);
break;
// PID file
case 'P':
strncpy(pid_file, optarg, sizeof(pid_file)-1);
break;
// print version and exit
case 'V':
printf("ttdnsd version %s\n", TTDNSD_VERSION);
exit(0);
// help
case 'h':
default:
printf("%s", HELP_STR);
exit(0);
break;
}
}
srand(time(NULL)); // This should use OpenSSL in the future
if (getuid() != 0 && (bind_port == DEFAULT_BIND_PORT || dochroot == 1)) {
printf("ttdnsd must run as root to bind to port 53 and chroot(2)\n");
exit(1);
}
if (!load_nameservers(resolvers)) { // perhaps we want to move this entirely into the chroot?
printf("can't open resolvers file %s, will try again after chroot\n", resolvers);
}
devnull = open("/dev/null", O_RDWR); // Leaked fd?
if (devnull < 0) {
printf("can't open /dev/null, exit\n");
exit(1);
}
// become a daemon
if (!debug) {
if (fork()) exit(0); // Could be clearer
setsid(); // Safe?
}
/* Why does this happen before the chroot? */
// write PID to file
if (strlen(pid_file) > 0) {
int pfd = open(pid_file, O_WRONLY|O_TRUNC|O_CREAT, 00644);
if (pfd < 0) {
printf("can't open pid file %s, exit\n", pid_file);
exit(1);
}
pf = fdopen(pfd, "w");
if (pf == NULL) {
printf("can't reopen pid file %s, exit\n", pid_file);
exit(1);
}
fprintf(pf, "%d", getpid());
fclose(pf);
close(pfd);
}
if (dochroot) {
if (chdir(chroot_dir)) {
printf("can't chdir to %s, exit\n", chroot_dir);
exit(1);
}
if (chroot(chroot_dir)) {
printf("can't chroot to %s, exit\n", chroot_dir);
exit(1);
}
env_ptr = getenv("TSOCKS_CONF_FILE");
if (env_ptr == NULL) {
strncpy(tsocks_conf, DEFAULT_TSOCKS_CONF, (sizeof(tsocks_conf)-1));
tsocks_conf[PATH_MAX-1] = '\0';
printf("chroot=%s, TSOCKS_CONF_FILE is unset - using default: %s\n", chroot_dir, DEFAULT_TSOCKS_CONF);
setenv("TSOCKS_CONF_FILE", tsocks_conf, 1);
} else {
strncpy(tsocks_conf, env_ptr, (sizeof(tsocks_conf)-1));
tsocks_conf[PATH_MAX-1] = '\0';
printf("tsocks_conf: %s\n", tsocks_conf);
}
if (access(DEFAULT_TSOCKS_CONF, R_OK) == 0 ){
printf("chroot=%s, default tsocks config available at %s\n", chroot_dir, DEFAULT_TSOCKS_CONF);
}
if (access(tsocks_conf, R_OK) != 0) { /* access() is a race condition and unsafe */
printf("chroot=%s, unable to access tsocks config set in TSOCKS_CONF_ENV at %s, exit\n", chroot_dir, tsocks_conf);
}
}
// privs will be dropped in server right after binding to port 53
if (log) {
printf("log init...\n");
lfd = open(DEFAULT_LOG, O_WRONLY|O_APPEND|O_CREAT, 00644);
if (lfd < 0) {
if (dochroot)
printf("chroot=%s ", chroot_dir);
printf("can't open log file %s, exit\n", DEFAULT_LOG);
exit(1);
} else {
printf("log file opened: %s\n", DEFAULT_LOG);
printf("log file opened as fd: %i\n", lfd);
}
printf("duping fds... check %s from here on out...\n", DEFAULT_LOG);
r = dup2(lfd, 1);
printf("dup2 says: %i\n", r);
r = dup2(lfd, 2);
printf("dup2 says: %i\n", r);
printf("closing original fd: %i...\n", lfd);
close(lfd);
dup2(devnull, 0);
close(devnull);
}
else if (!debug) {
dup2(devnull, 0);
dup2(devnull, 1);
dup2(devnull, 2);
close(devnull);
}
printf("starting server...\n");
r = server(bind_ip, bind_port);
if (r != 0)
printf("something went wrong with the server: %i\n", r);
if (r == -1)
printf("failed to bind udp server to %s:%i: %i\n", bind_ip, bind_port, r);
printf("ttdnsd exiting now!\n");
exit(r);
}