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c-libp2p/routing/kademlia.c

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/* For crypt */
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/time.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <sys/signal.h>
#include <pthread.h>
#include <libp2p/crypto/sha256.h>
#include <libp2p/routing/kademlia.h>
#include <libp2p/routing/dht.h>
#include <multiaddr/multiaddr.h>
extern FILE *dht_debug;
#define MAX_BOOTSTRAP_NODES 20
static struct sockaddr_storage bootstrap_nodes[MAX_BOOTSTRAP_NODES];
static int num_bootstrap_nodes = 0;
struct bs_struct {
char *ip;
uint16_t port;
} bootstrap_list[] = {
};
pthread_t pth_kademlia, pth_announce;
time_t tosleep = 0;
int kfd = -1;
int net_family = 0;
volatile int8_t searching = 0; // search lock, -1 to busy, 0 to free, 1 to running.
volatile char hash[20]; // hash to be search or announce.
volatile uint16_t announce_port = 0;
volatile int8_t closing = 0;
#define ANNOUNCE_WAIT_TIME (28 * 60) // Wait 28 minutes.
#define ANNOUNCE_WAIT_TOLERANCE 60
struct announce_struct {
unsigned char hash[sizeof hash];
uint16_t port;
unsigned int time;
struct announce_struct *next;
} *announce_list = NULL;
#define DHT_MAX_IPV4 50
#define DHT_MAX_IPV6 10
struct ipv4_struct {
uint32_t ip;
uint16_t port;
};
struct ipv6_struct {
uint8_t ip[16];
uint16_t port;
};
struct search_struct {
unsigned char hash[sizeof hash];
uint8_t ipv4_count;
uint8_t ipv6_count;
struct ipv4_struct ipv4[DHT_MAX_IPV4];
struct ipv6_struct ipv6[DHT_MAX_IPV6];
struct search_struct *next;
} *search_result = NULL;
/***
* The call-back function is called by the DHT whenever something
* interesting happens. Right now, it only happens when we get a new value or
* when a search completes, but this may be extended in future versions.
* @param closure
* @param event the event
* @param info_hash the hash to work with
* @param data the new value to be added
* @param data_len the length of the data
*/
static void callback(void *closure, int event, const unsigned char *info_hash, const void *data, size_t data_len) {
struct search_struct *sp, *rp = NULL; // struct pointer and result pointer
switch (event) {
case DHT_EVENT_VALUES:
case DHT_EVENT_VALUES6:
if (dht_debug) {
fprintf(dht_debug, "Received %d values.\n", (int)(data_len / 6));
}
// Find the item in the list.
for (rp = search_result ; rp ; rp = rp->next) {
if (memcmp(rp->hash, info_hash, sizeof hash) == 0) { // Found.
int i;
if (event == DHT_EVENT_VALUES) { // IPv4
struct ipv4_struct ipv4;
if (rp->ipv4_count == DHT_MAX_IPV4) { // Full
return;
}
// Make sure the data is in struct format.
memcpy(&ipv4.ip, data, 4);
memcpy(&ipv4.port, data+4, 2);
ipv4.port = ntohs(ipv4.port);
for (i = 0 ; i < rp->ipv4_count ; i++) {
if (memcmp(&rp->ipv4[i], &ipv4, sizeof ipv4) == 0) {
return; // Alread in the list.
}
}
// Not in the list, then add.
memcpy(&rp->ipv4[rp->ipv4_count], &ipv4, sizeof ipv4);
rp->ipv4_count++;
} else { // IPv6
struct ipv6_struct ipv6;
if (rp->ipv6_count == DHT_MAX_IPV6) { // Full
return;
}
// Make sure the data is in struct format.
memcpy(&ipv6.ip, data, 16);
memcpy(&ipv6.port, data+16, 2);
for (i = 0 ; i < rp->ipv6_count ; i++) {
if (memcmp(&rp->ipv6[i], &ipv6, sizeof ipv6) == 0) {
return; // Alread in the list.
}
}
// Not in the list, then add.
memcpy(&rp->ipv6[rp->ipv6_count], &ipv6, sizeof ipv6);
rp->ipv6_count++;
}
return;
}
}
break; // Not found, how can EVENT_VALUE may occur before SEARCH_DONE?
case DHT_EVENT_SEARCH_DONE:
case DHT_EVENT_SEARCH_DONE6:
if (dht_debug) {
fprintf(dht_debug, "Search done.\n");
}
if (search_result) {
// Try to find the item in the list.
for (sp = search_result ; sp->next ; sp = sp->next) {
if (memcmp(sp->hash, info_hash, sizeof hash) == 0) { // Found.
rp = sp;
break;
}
}
if (!rp) {
rp = malloc(sizeof(struct search_struct));
if (!rp) return; // Abort, out of memory.
memset(rp, 0, sizeof(struct search_struct));
memcpy(rp->hash, info_hash, sizeof hash);
sp->next = rp; // Insert in the list.
}
} else {
rp = malloc(sizeof(struct search_struct));
if (!rp) return; // Abort, out of memory.
memset(rp, 0, sizeof(struct search_struct));
memcpy(rp->hash, info_hash, sizeof hash);
search_result = rp; // Insert first item in the list.
}
break;
default:
break;
}
}
int start_kademlia_multiaddress(struct MultiAddress* address, char* peer_id, int timeout, struct Libp2pVector* bootstrap_addresses) {
int port = multiaddress_get_ip_port(address);
int family = multiaddress_get_ip_family(address);
int fd = socket(family, SOCK_DGRAM, 0);
if (fd < 0)
return 0;
struct sockaddr_in serv_addr;
serv_addr.sin_family = family;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
serv_addr.sin_port = port;
if (bind(fd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) != 0)
return 0;
return start_kademlia(fd, family, peer_id, timeout, bootstrap_addresses);
}
/***
* Start the kademlia service
* @param net_fd the file descriptor of the address/socket already bound
* @param family ip4 or ip6
* @param peer_id the first 20 chars of the public PeerID in a null terminated string
* @param timeout seconds before a select() timeout
*/
int start_kademlia(int net_fd, int family, char* peer_id, int timeout, struct Libp2pVector* bootstrap_addresses)
{
int rc, i, len;
unsigned char id[sizeof hash];
struct sockaddr_in sa;
dht_debug = stderr;
len = bootstrap_addresses->total;
if (len > MAX_BOOTSTRAP_NODES) {
len = MAX_BOOTSTRAP_NODES; // limit array length
}
memset(&sa, 0, sizeof sa);
char* ip = NULL;
for (i = 0 ; i < len ; i++) {
struct MultiAddress* addr = (struct MultiAddress*)libp2p_utils_vector_get(bootstrap_addresses, i);
if (ip != NULL)
free(ip);
if (multiaddress_is_ip(addr)) {
multiaddress_get_ip_address(addr, &ip);
if (family == AF_INET6 && multiaddress_is_ip6(addr)) {
if (inet_pton(AF_INET6, ip, &(sa.sin_addr.s_addr)) == 1)
sa.sin_family = AF_INET6;
else
continue;
} else {
if (inet_pton(AF_INET , ip, &(sa.sin_addr.s_addr)) == 1)
sa.sin_family = AF_INET;
else
continue;
}
} else {
continue; // not an ipv6 or ipv4?
}
sa.sin_port = htons (multiaddress_get_ip_port(addr));
memcpy(&bootstrap_nodes[num_bootstrap_nodes++], &sa, sizeof(sa));
}
if (ip != NULL)
free(ip);
dht_hash (id, sizeof(id), peer_id, strlen(peer_id), NULL, 0, NULL, 0);
if (family == AF_INET6) {
rc = dht_init(-1, net_fd, id, NULL);
} else {
rc = dht_init(net_fd, -1, id, NULL);
}
if (rc < 0) {
return rc;
}
/* 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++) {
// for debugging
int retVal =
dht_ping_node((struct sockaddr*)&bootstrap_nodes[i],
sizeof (bootstrap_nodes[i]));
fprintf(stderr, "ping returned %d\n", retVal);
usleep(random() % 100000);
}
// TODO: Read cache nodes from file and load using dht_insert_node.
kfd = net_fd;
net_family = family;
tosleep = timeout;
rc = pthread_create(&pth_kademlia, NULL, kademlia_thread, NULL);
if (rc) {
return rc; // error
}
return pthread_create(&pth_announce, NULL, announce_thread, NULL);
}
void stop_kademlia (void)
{
if (kfd != -1) {
closing = 1;
pthread_cancel(pth_announce);
// Wait kademlia_thread finish.
pthread_join(pth_kademlia, NULL);
dht_uninit();
close (kfd);
kfd = -1;
}
}
void *kademlia_thread (void *ptr)
{
int rc;
struct timeval tv;
fd_set readfds;
char buf[4096];
struct sockaddr from;
socklen_t fromlen;
for(;;) {
tv.tv_sec = tosleep;
tv.tv_usec = random() % 1000000;
FD_ZERO(&readfds);
FD_SET(kfd, &readfds);
rc = select(kfd + 1, &readfds, NULL, NULL, &tv);
if(rc < 0) {
if(errno != EINTR) {
perror("select");
sleep(1);
}
}
if(rc > 0 && FD_ISSET(kfd, &readfds)) {
fromlen = sizeof(from);
rc = recvfrom(kfd, buf, sizeof(buf) - 1, 0,
(struct sockaddr*)&from, &fromlen);
if (rc < 0) {
if (errno == EAGAIN || errno == EWOULDBLOCK) {
continue;
} else {
fprintf(stderr, "kademlia_thread:recvfrom failed with %d\n", errno);
continue;
}
}
buf[rc] = '\0';
rc = dht_periodic(buf, rc, (struct sockaddr*)&from, fromlen,
&tosleep, callback, NULL);
} else {
rc = dht_periodic(NULL, 0, NULL, 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 > 0) {
unsigned char h[sizeof hash];
int i;
for (i = 0 ; i < sizeof hash ; i++) {
h[i] = hash[i]; // Copy hash array to new array so can call
// dht_search without volatile variable.
}
dht_search(h, announce_port, net_family, callback, NULL);
searching = 0;
}
if(closing) {
// TODO: Create a routine to save the cache nodes in the file sometimes and before closing.
return 0; // end thread.
}
}
return (void*)1;
}
/**
* Search for a hash
* @param id the hash to look for
* @param port the port if it is available
* @param to the time out
* @returns the time left
*/
int search_kademlia_internal (unsigned char* id, int port, int to)
{
int i;
while (searching != 0) {
i = random() % 100000;
if (i > to) {
return 0; // timeout waiting a chance
}
usleep(i);
to -= i;
}
searching = -1; // lock.
for (i = 0 ; i < sizeof hash ; i++) {
hash[i] = id[i];
}
announce_port = port;
searching = 1; // search.
return to;
}
void *announce_thread (void *ptr)
{
unsigned int wait;
struct announce_struct *n, *p;
for(;;) {
if (announce_list) {
unsigned int now, minus_time = ((unsigned int) -1);
p = NULL;
// find max wait value.
for (n = announce_list ; n ; n = n->next) {
if (n->time < minus_time) {
minus_time = n->time;
p = n;
}
}
if (p) {
now = time(NULL);
if ((minus_time + ANNOUNCE_WAIT_TIME) > (now + ANNOUNCE_WAIT_TOLERANCE)) {
wait = ANNOUNCE_WAIT_TIME - (now - minus_time);
sleep (wait);
} else {
if (p) {
search_kademlia_internal (p->hash, p->port, ANNOUNCE_WAIT_TOLERANCE * 1000000);
p->time = time(NULL);
}
}
continue;
}
}
// Empty list, just wait.
sleep (ANNOUNCE_WAIT_TIME);
}
return (void*)1;
}
int announce_kademlia (char* peer_id, uint16_t port)
{
unsigned char id[sizeof hash];
struct announce_struct *n, *p;
dht_hash (id, sizeof(id), peer_id, strlen(peer_id), NULL, 0, NULL, 0);
for (n = announce_list ; n ; n = n->next) {
if (memcmp(n->hash, id, sizeof id) == 0) {
return 0; // Already on the list.
}
if (! (n->next)) {
break; // Keep n->next at the insertion point.
}
}
if ((p = malloc (sizeof(struct announce_struct))) == NULL) {
return 0; // Fail to alloc.
}
search_kademlia_internal (id, port, ANNOUNCE_WAIT_TOLERANCE * 1000000);
memcpy(p->hash, id, sizeof id);
p->port = port;
p->next = NULL;
p->time = time(NULL);
if (!announce_list) {
announce_list = p;
} else {
n->next = p;
}
return 1; // Announced and added to the list.
}
struct MultiAddress** search_kademlia(char* peer_id, int timeout)
{
unsigned char id[sizeof hash];
int i, to = timeout * 1000000;
struct search_struct *rp; // result pointer
struct MultiAddress **ret;
if (kfd == -1) {
return NULL; // start thread first.
}
dht_hash (id, sizeof(id), peer_id, strlen(peer_id), NULL, 0, NULL, 0);
//TODO: Is this the right place to ask the net?
dht_search((unsigned char*)peer_id, 0, AF_INET, NULL, NULL);
to = search_kademlia_internal (id, 0, to);
if (to == 0) return NULL; // time out.
// Wait for search completion.
for(;;) {
i = random() % 100000;
if (i > to) {
return NULL; // timeout.
}
usleep(i);
for (rp = search_result ; rp ; rp = rp->next) {
if (memcmp(rp->hash, id, sizeof hash) == 0) { // Found.
char ipstr[INET6_ADDRSTRLEN + 1];
char str[sizeof ipstr + 16];
int c = 0;
// Wait for result or time out.
while (to > 0 &&
search_result->ipv4_count == 0 &&
search_result->ipv6_count == 0) {
to = search_kademlia_internal (id, 0, to); // Repeat search to collect result.
usleep(2000000); // Wait a few seconds for the result.
to -= 2000000;
}
if (search_result->ipv4_count == 0 ||
search_result->ipv6_count == 0) return NULL; // no result.
ret = calloc(search_result->ipv4_count + search_result->ipv6_count + 1, // IPv4 + IPv6 itens and a NULL terminator.
sizeof (struct MultiAddress*)); // array of pointer.
if (!ret) {
return NULL;
}
for (i = 0 ; i < search_result->ipv4_count ; i++) {
if (inet_ntop(AF_INET, &search_result->ipv4[i].ip, ipstr, sizeof ipstr)) {
snprintf (str, sizeof str, "/ip4/%s/tcp/%d", ipstr, search_result->ipv4[i].port);
if (dht_debug) {
fprintf(dht_debug, "SEARCH %s (%d) = %s\n", peer_id, c, str);
}
ret[c] = multiaddress_new_from_string (str);
if (ret[c] > 0) { // Sucess.
c++;
}
}
}
for (i = 0 ; i < search_result->ipv6_count ; i++) {
if (inet_ntop(AF_INET6, search_result->ipv6[i].ip, ipstr, sizeof ipstr)) {
snprintf (str, sizeof str, "/ip6/%s/tcp/%d", ipstr, search_result->ipv6[i].port);
if (dht_debug) {
fprintf(dht_debug, "SEARCH %s (%d) = %s\n", peer_id, c, str);
}
ret[c] = multiaddress_new_from_string (str);
if (ret[c] > 0) { // Sucess.
c++;
}
}
}
ret[c] = NULL; // NULL terminator.
return ret;
}
}
to -= i;
}
return NULL;
}
int ping_kademlia (char *ip, uint16_t port)
{
struct sockaddr_in sa;
if (inet_pton(AF_INET6, ip, &(sa.sin_addr.s_addr)) == 1) {
sa.sin_family = AF_INET6;
} if (inet_pton(AF_INET, ip, &(sa.sin_addr.s_addr)) == 1) {
sa.sin_family = AF_INET;
} else {
return 0;
}
sa.sin_port = htons (port);
dht_ping_node((struct sockaddr*)&sa, sizeof sa);
//usleep(random() % 100000);
return 1;
}
/* Functions called by the DHT. */
int dht_blacklisted (const struct sockaddr *sa, int salen)
{
return 0;
}
/* We need to provide a reasonably strong cryptographic hashing function.
libp2p_crypto_hashing_sha256 */
void dht_hash (void *hash_return, int hash_size,
const void *v1, int len1,
const void *v2, int len2,
const void *v3, int len3)
{
int len = len1 + len2 + len3;
unsigned char *in, out[32];
if (!hash_return || hash_size==0 || len==0) {
return; // invalid param.
}
in = malloc (len);
if (in) {
memcpy(in, v1, len1);
memcpy(in+len1, v2, len2);
memcpy(in+len1+len2, v3, len3);
if ( libp2p_crypto_hashing_sha256 (in, len, out) ) {
if (hash_size > sizeof(out)) {
memset ((char*)hash_return + sizeof(out), 0, hash_size - sizeof(out));
hash_size = sizeof(out);
}
memcpy(hash_return, out, hash_size);
}
free (in);
}
}
int dht_random_bytes (void *buf, size_t size)
{
int fd, rc = 0, save;
size_t len = 0;
fd = open("/dev/urandom", O_RDONLY);
if (fd < 0) {
return fd;
}
while (len < size) {
rc = read (fd, buf + len, size - len);
if (rc < 0) {
if (errno == EINTR || errno == EAGAIN) {
continue; // not fatal, try again.
}
if (errno == EWOULDBLOCK && len > 0) {
rc = len;
}
break; // fail.
}
len += rc;
}
if (len > 0 && rc >= 0) {
rc = len;
}
save = errno;
close(fd);
errno = save;
return rc;
}
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