/*
* Lookup known nodes that are nearest to the given id.
*/
int kad_lookup_value( const char _query[], IP addr_array[], size_t *addr_num ) {
char query[QUERY_MAX_SIZE];
struct results_t *results;
int is_new;
int rc;
if( query_sanitize( query, sizeof(query), _query ) != 0 ) {
return -2;
}
log_debug( "KAD: Lookup string: %s", query );
dht_lock();
/* Find existing or create new item */
results = results_add( query, &is_new );
if( results && is_new ) {
/* Search own announced values */
kad_lookup_local_values( results );
}
if( results == NULL ) {
/* Failed to create a new search */
rc = -1;
} else if( results->done ) {
/*
* The search exists already but has finished. Restart the search when
* no results have been found or more than half of the searches lifetime
* has expired.
*/
if( results_entries_count( results ) == 0 ||
(time_now_sec() - results->start_time) > (MAX_SEARCH_LIFETIME / 2)
) {
/* Mark search as in progress */
results_done( results, 0 );
/* Start another search for this id */
dht_search( results->id, 0, gconf->af, dht_callback_func, NULL );
}
rc = 2;
} else if( is_new ) {
/* Start a new DHT search */
dht_search( results->id, 0, gconf->af, dht_callback_func, NULL );
rc = 1;
} else {
/* Search is still running */
rc = 0;
}
/* Collect addresses to be returned */
*addr_num = results_collect( results, addr_array, *addr_num );
dht_unlock();
return rc;
}
/*
* Lookup known nodes that are nearest to the given id.
*/
int kad_lookup_value( const char query[], IP addr_array[], size_t *addr_num ) {
char hexbuf[SHA1_HEX_LENGTH+1];
UCHAR id[SHA1_BIN_LENGTH];
int rc;
/* Generate the id, e.g. id = sha1(query) */
id_compute( id, query );
log_debug( "KAD: Lookup '%s' as '%s'.", query, str_id( id, hexbuf ) );
dht_lock();
rc = results_collect( id, addr_array, *addr_num );
if( rc < 0 ) {
/* No results item found - no search in progress - start search */
dht_lock();
results_add( id, query );
dht_search( id, 0, gconf->af, dht_callback_func, NULL );
dht_unlock();
*addr_num = 0;
rc = -1;
} else {
*addr_num = rc;
rc = 0;
}
dht_unlock();
return rc;
}
/*
* Find nodes that are near the given id and announce to them
* that this node can satisfy the given id on the given port
*/
int kad_announce( const UCHAR *id, int port ) {
if( port < 1 || port > 65535 ) {
return -1;
}
dht_lock();
dht_search( id, port, gconf->af, dht_callback_func, NULL );
dht_unlock();
return 0;
}
static void
opget_dns_callback(f4_ctx_t* ctx, struct f4op *op, struct evdns_server_request *req) {
assert( ctx != NULL );
assert( op != NULL );
assert( req != NULL );
f4op_get_t *get_op = (f4op_get_t *)op->data;
get_op->request = req;
// XXX: re-workt dht_search to use ipv4/ipv6 as available rather than
// explicitly specifying AF_INET or AF_INET6
// XXX: Nor do we care about a callback, that's handled elsewhere
dht_search( op->id, 0, AF_INET, NULL, NULL );
}
int
main(int argc, char **argv)
{
int i, rc, fd;
int s = -1, s6 = -1, port;
int have_id = 0;
unsigned char myid[20];
time_t tosleep = 0;
char *id_file = "dht-example.id";
int opt;
int quiet = 0, ipv4 = 1, ipv6 = 1;
struct sockaddr_in sin;
struct sockaddr_in6 sin6;
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
memset(&sin6, 0, sizeof(sin6));
sin6.sin6_family = AF_INET6;
while(1) {
opt = getopt(argc, argv, "q46b:i:");
if(opt < 0)
break;
switch(opt) {
case 'q': quiet = 1; break;
case '4': ipv6 = 0; break;
case '6': ipv4 = 0; break;
case 'b': {
char buf[16];
int rc;
rc = inet_pton(AF_INET, optarg, buf);
if(rc == 1) {
memcpy(&sin.sin_addr, buf, 4);
break;
}
rc = inet_pton(AF_INET6, optarg, buf);
if(rc == 1) {
memcpy(&sin6.sin6_addr, buf, 16);
break;
}
goto usage;
}
break;
case 'i':
id_file = optarg;
break;
default:
goto usage;
}
}
/* Ids need to be distributed evenly, so you cannot just use your
bittorrent id. Either generate it randomly, or take the SHA-1 of
something. */
fd = open(id_file, O_RDONLY);
if(fd >= 0) {
rc = read(fd, myid, 20);
if(rc == 20)
have_id = 1;
close(fd);
}
fd = open("/dev/urandom", O_RDONLY);
if(fd < 0) {
perror("open(random)");
exit(1);
}
if(!have_id) {
int ofd;
rc = read(fd, myid, 20);
if(rc < 0) {
perror("read(random)");
exit(1);
}
have_id = 1;
close(fd);
ofd = open(id_file, O_WRONLY | O_CREAT | O_TRUNC, 0666);
if(ofd >= 0) {
rc = write(ofd, myid, 20);
if(rc < 20)
unlink(id_file);
close(ofd);
}
}
{
unsigned seed;
read(fd, &seed, sizeof(seed));
srandom(seed);
}
close(fd);
if(argc < 2)
goto usage;
i = optind;
if(argc < i + 1)
goto usage;
port = atoi(argv[i++]);
if(port <= 0 || port >= 0x10000)
goto usage;
while(i < argc) {
struct addrinfo hints, *info, *infop;
memset(&hints, 0, sizeof(hints));
hints.ai_socktype = SOCK_DGRAM;
if(!ipv6)
hints.ai_family = AF_INET;
else if(!ipv4)
hints.ai_family = AF_INET6;
else
hints.ai_family = 0;
rc = getaddrinfo(argv[i], argv[i + 1], &hints, &info);
if(rc != 0) {
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rc));
exit(1);
}
i++;
if(i >= argc)
goto usage;
infop = info;
while(infop) {
memcpy(&bootstrap_nodes[num_bootstrap_nodes],
infop->ai_addr, infop->ai_addrlen);
infop = infop->ai_next;
num_bootstrap_nodes++;
}
freeaddrinfo(info);
i++;
}
/* If you set dht_debug to a stream, every action taken by the DHT will
be logged. */
if(!quiet)
dht_debug = stdout;
/* We need an IPv4 and an IPv6 socket, bound to a stable port. Rumour
has it that uTorrent works better when it is the same as your
Bittorrent port. */
if(ipv4) {
s = socket(PF_INET, SOCK_DGRAM, 0);
if(s < 0) {
perror("socket(IPv4)");
}
}
if(ipv6) {
s6 = socket(PF_INET6, SOCK_DGRAM, 0);
if(s6 < 0) {
perror("socket(IPv6)");
}
}
if(s < 0 && s6 < 0) {
fprintf(stderr, "Eek!");
exit(1);
}
if(s >= 0) {
sin.sin_port = htons(port);
rc = bind(s, (struct sockaddr*)&sin, sizeof(sin));
if(rc < 0) {
perror("bind(IPv4)");
exit(1);
}
}
if(s6 >= 0) {
int rc;
int val = 1;
rc = setsockopt(s6, IPPROTO_IPV6, IPV6_V6ONLY,
(char *)&val, sizeof(val));
if(rc < 0) {
perror("setsockopt(IPV6_V6ONLY)");
exit(1);
}
/* BEP-32 mandates that we should bind this socket to one of our
global IPv6 addresses. In this simple example, this only
happens if the user used the -b flag. */
sin6.sin6_port = htons(port);
rc = bind(s6, (struct sockaddr*)&sin6, sizeof(sin6));
if(rc < 0) {
perror("bind(IPv6)");
exit(1);
}
}
/* Init the dht. This sets the socket into non-blocking mode. */
rc = dht_init(s, s6, myid, (unsigned char*)"JC\0\0");
if(rc < 0) {
perror("dht_init");
exit(1);
}
init_signals();
/* For bootstrapping, we need an initial list of nodes. This could be
hard-wired, but can also be obtained from the nodes key of a torrent
file, or from the PORT bittorrent message.
Dht_ping_node is the brutal way of bootstrapping -- it actually
sends a message to the peer. If you're going to bootstrap from
a massive number of nodes (for example because you're restoring from
a dump) and you already know their ids, it's better to use
dht_insert_node. If the ids are incorrect, the DHT will recover. */
for(i = 0; i < num_bootstrap_nodes; i++) {
dht_ping_node((struct sockaddr*)&bootstrap_nodes[i],
sizeof(bootstrap_nodes[i]));
usleep(random() % 100000);
}
while(1) {
struct timeval tv;
fd_set readfds;
tv.tv_sec = tosleep;
tv.tv_usec = random() % 1000000;
FD_ZERO(&readfds);
if(s >= 0)
FD_SET(s, &readfds);
if(s6 >= 0)
FD_SET(s6, &readfds);
rc = select(s > s6 ? s + 1 : s6 + 1, &readfds, NULL, NULL, &tv);
if(rc < 0) {
if(errno != EINTR) {
perror("select");
sleep(1);
}
}
if(exiting)
break;
rc = dht_periodic(rc > 0, &tosleep, callback, NULL);
if(rc < 0) {
if(errno == EINTR) {
continue;
} else {
perror("dht_periodic");
if(rc == EINVAL || rc == EFAULT)
abort();
tosleep = 1;
}
}
/* This is how you trigger a search for a torrent hash. If port
(the second argument) is non-zero, it also performs an announce.
Since peers expire announced data after 30 minutes, it's a good
idea to reannounce every 28 minutes or so. */
if(searching) {
if(s >= 0)
dht_search(hash, 0, AF_INET, callback, NULL);
if(s6 >= 0)
dht_search(hash, 0, AF_INET6, callback, NULL);
searching = 0;
}
/* For debugging, or idle curiosity. */
if(dumping) {
dht_dump_tables(stdout);
dumping = 0;
}
}
{
struct sockaddr_in sin[500];
struct sockaddr_in6 sin6[500];
int num = 500, num6 = 500;
int i;
i = dht_get_nodes(sin, &num, sin6, &num6);
printf("Found %d (%d + %d) good nodes.\n", i, num, num6);
}
dht_uninit(1);
return 0;
usage:
printf("Usage: dht-example [-q] [-4] [-6] [-i filename] [-b address]...\n"
" port [address port]...\n");
exit(1);
}
