HGKeeper

/**

* @file stun.c STUN (RFC3489) Implementation

* @ingroup core

/* purple

* STUN implementation inspired by jstun [http://jstun.javawi.de/]

* Purple is the legal property of its developers, whose names are too numerous

* to list here. Please refer to the COPYRIGHT file distributed with this

* source distribution.

* This program is free software; you can redistribute it and/or modify

* it under the terms of the GNU General Public License as published by

* the Free Software Foundation; either version 2 of the License, or

* (at your option) any later version.

* This program is distributed in the hope that it will be useful,

* but WITHOUT ANY WARRANTY; without even the implied warranty of

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

* GNU General Public License for more details.

* You should have received a copy of the GNU General Public License

* along with this program; if not, write to the Free Software

* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111-1301 USA

#include "internal.h"

#ifndef _WIN32

#include <net/if.h>

#include <sys/ioctl.h>

#endif

/* Solaris */

#if defined (__SVR4) && defined (__sun)

#include <sys/sockio.h>

#endif

#include "debug.h"

#include "account.h"

#include "dnsquery.h"

#include "dnssrv.h"

#include "network.h"

#include "proxy.h"

#include "stun.h"

#include "prefs.h"

#define MSGTYPE_BINDINGREQUEST 0x0001

#define MSGTYPE_BINDINGRESPONSE 0x0101

#define ATTRIB_MAPPEDADDRESS 0x0001

struct stun_header {

guint16 type;

guint16 len;

guint32 transid[4];

};

struct stun_attrib {

guint16 type;

guint16 len;

};

#ifdef NOTYET

struct stun_change {

struct stun_header hdr;

struct stun_attrib attrib;

char value[4];

};

#endif

struct stun_conn {

int fd;

struct sockaddr_in addr;

int test;

int retry;

guint incb;

guint timeout;

struct stun_header *packet;

size_t packetsize;

};

static PurpleStunNatDiscovery nattype = {

PURPLE_STUN_STATUS_UNDISCOVERED,

PURPLE_STUN_NAT_TYPE_PUBLIC_IP,

"\0", NULL, 0};

static GSList *callbacks = NULL;

static void close_stun_conn(struct stun_conn *sc) {

if (sc->incb)

purple_input_remove(sc->incb);

if (sc->timeout)

purple_timeout_remove(sc->timeout);

if (sc->fd)

close(sc->fd);

g_free(sc);

}

static void do_callbacks(void) {

while (callbacks) {

StunCallback cb = callbacks->data;

if (cb)

cb(&nattype);

callbacks = g_slist_delete_link(callbacks, callbacks);

}

static gboolean timeoutfunc(gpointer data) {

struct stun_conn *sc = data;

if(sc->retry >= 2) {

purple_debug_warning("stun", "request timed out, giving up.\n");

if(sc->test == 2)

nattype.type = PURPLE_STUN_NAT_TYPE_SYMMETRIC;

/* set unknown */

nattype.status = PURPLE_STUN_STATUS_UNKNOWN;

nattype.lookup_time = time(NULL);

/* callbacks */

do_callbacks();

/* we don't need to remove the timeout (returning FALSE) */

sc->timeout = 0;

close_stun_conn(sc);

return FALSE;

}

purple_debug_info("stun", "request timed out, retrying.\n");

sc->retry++;

if (sendto(sc->fd, sc->packet, sc->packetsize, 0,

(struct sockaddr *)&(sc->addr), sizeof(struct sockaddr_in)) !=

(gssize)sc->packetsize)

{

purple_debug_warning("stun", "sendto failed\n");

return FALSE;

}

return TRUE;

}

#ifdef NOTYET

static void do_test2(struct stun_conn *sc) {

struct stun_change data;

data.hdr.type = htons(0x0001);

data.hdr.len = 0;

data.hdr.transid[0] = rand();

data.hdr.transid[1] = ntohl(((int)'g' << 24) + ((int)'a' << 16) + ((int)'i' << 8) + (int)'m');

data.hdr.transid[2] = rand();

data.hdr.transid[3] = rand();

data.attrib.type = htons(0x003);

data.attrib.len = htons(4);

data.value[3] = 6;

sc->packet = (struct stun_header*)&data;

sc->packetsize = sizeof(struct stun_change);

sc->retry = 0;

sc->test = 2;

sendto(sc->fd, sc->packet, sc->packetsize, 0, (struct sockaddr *)&(sc->addr), sizeof(struct sockaddr_in));

sc->timeout = purple_timeout_add(500, (GSourceFunc) timeoutfunc, sc);

}

#endif

static void reply_cb(gpointer data, gint source, PurpleInputCondition cond) {

struct stun_conn *sc = data;

char buffer[65536];

char *tmp;

gssize len;

struct in_addr in;

struct stun_attrib *attrib;

struct stun_header *hdr;

struct ifconf ifc;

struct ifreq *ifr;

struct sockaddr_in *sinptr;

memset(&in, 0, sizeof(in));

len = recv(source, buffer, sizeof(buffer) - 1, 0);

if (len < 0) {

purple_debug_warning("stun", "unable to read stun response\n");

return;

}

buffer[len] = '\0';

if ((gsize)len < sizeof(struct stun_header)) {

purple_debug_warning("stun", "got invalid response\n");

return;

}

hdr = (struct stun_header*) buffer;

if ((gsize)len != (ntohs(hdr->len) + sizeof(struct stun_header))) {

purple_debug_warning("stun", "got incomplete response\n");

return;

}

/* wrong transaction */

if(hdr->transid[0] != sc->packet->transid[0]

|| hdr->transid[1] != sc->packet->transid[1]

|| hdr->transid[2] != sc->packet->transid[2]

|| hdr->transid[3] != sc->packet->transid[3]) {

purple_debug_warning("stun", "got wrong transid\n");

return;

}

if(sc->test==1) {

if (hdr->type != MSGTYPE_BINDINGRESPONSE) {

purple_debug_warning("stun",

"Expected Binding Response, got %d\n",

hdr->type);

return;

}

tmp = buffer + sizeof(struct stun_header);

while((buffer + len) > (tmp + sizeof(struct stun_attrib))) {

attrib = (struct stun_attrib*) tmp;

tmp += sizeof(struct stun_attrib);

if (!((buffer + len) > (tmp + ntohs(attrib->len))))

break;

if(attrib->type == htons(ATTRIB_MAPPEDADDRESS)

&& ntohs(attrib->len) == 8) {

char *ip;

/* Skip the first unused byte,

* the family(1 byte), and the port(2 bytes);

* then read the 4 byte IPv4 address */

memcpy(&in.s_addr, tmp + 4, 4);

ip = inet_ntoa(in);

if(ip)

g_strlcpy(nattype.publicip, ip, sizeof(nattype.publicip));

}

tmp += ntohs(attrib->len);

}

purple_debug_info("stun", "got public ip %s\n", nattype.publicip);

nattype.status = PURPLE_STUN_STATUS_DISCOVERED;

nattype.type = PURPLE_STUN_NAT_TYPE_UNKNOWN_NAT;

nattype.lookup_time = time(NULL);

/* is it a NAT? */

ifc.ifc_len = sizeof(buffer);

ifc.ifc_req = (struct ifreq *) buffer;

ioctl(source, SIOCGIFCONF, &ifc);

tmp = buffer;

while(tmp < buffer + ifc.ifc_len) {

ifr = (struct ifreq *) tmp;

tmp += sizeof(struct ifreq);

if(ifr->ifr_addr.sa_family == AF_INET) {

/* we only care about ipv4 interfaces */

sinptr = (struct sockaddr_in *) &ifr->ifr_addr;

if(sinptr->sin_addr.s_addr == in.s_addr) {

/* no NAT */

purple_debug_info("stun", "no nat\n");

nattype.type = PURPLE_STUN_NAT_TYPE_PUBLIC_IP;

}

#ifndef NOTYET

close_stun_conn(sc);

do_callbacks();

#else

purple_timeout_remove(sc->timeout);

sc->timeout = 0;

do_test2(sc);

} else if(sc->test == 2) {

close_stun_conn(sc);

nattype.type = PURPLE_STUN_NAT_TYPE_FULL_CONE;

do_callbacks();

#endif

}

static void hbn_listen_cb(int fd, gpointer data) {

GSList *hosts = data;

struct stun_conn *sc;

static struct stun_header hdr_data;

if(fd < 0) {

nattype.status = PURPLE_STUN_STATUS_UNKNOWN;

nattype.lookup_time = time(NULL);

do_callbacks();

return;

}

sc = g_new0(struct stun_conn, 1);

sc->fd = fd;

sc->addr.sin_family = AF_INET;

sc->addr.sin_port = htons(purple_network_get_port_from_fd(fd));

sc->addr.sin_addr.s_addr = INADDR_ANY;

sc->incb = purple_input_add(fd, PURPLE_INPUT_READ, reply_cb, sc);

hosts = g_slist_delete_link(hosts, hosts);

memcpy(&(sc->addr), hosts->data, sizeof(struct sockaddr_in));

g_free(hosts->data);

hosts = g_slist_delete_link(hosts, hosts);

while (hosts) {

hosts = g_slist_delete_link(hosts, hosts);

g_free(hosts->data);

hosts = g_slist_delete_link(hosts, hosts);

}

hdr_data.type = htons(MSGTYPE_BINDINGREQUEST);

hdr_data.len = 0;

hdr_data.transid[0] = rand();

hdr_data.transid[1] = ntohl(((int)'g' << 24) + ((int)'a' << 16) + ((int)'i' << 8) + (int)'m');

hdr_data.transid[2] = rand();

hdr_data.transid[3] = rand();

if(sendto(sc->fd, &hdr_data, sizeof(struct stun_header), 0,

(struct sockaddr *)&(sc->addr),

sizeof(struct sockaddr_in)) < (gssize)sizeof(struct stun_header)) {

nattype.status = PURPLE_STUN_STATUS_UNKNOWN;

nattype.lookup_time = time(NULL);

do_callbacks();

close_stun_conn(sc);

return;

}

sc->test = 1;

sc->packet = &hdr_data;

sc->packetsize = sizeof(struct stun_header);

sc->timeout = purple_timeout_add(500, (GSourceFunc) timeoutfunc, sc);

}

static void hbn_cb(GSList *hosts, gpointer data, const char *error_message) {

if(!hosts || !hosts->data) {

nattype.status = PURPLE_STUN_STATUS_UNDISCOVERED;

nattype.lookup_time = time(NULL);

do_callbacks();

return;

}

if (!purple_network_listen_range(12108, 12208, SOCK_DGRAM, hbn_listen_cb, hosts)) {

while (hosts) {

hosts = g_slist_delete_link(hosts, hosts);

g_free(hosts->data);

hosts = g_slist_delete_link(hosts, hosts);

}

nattype.status = PURPLE_STUN_STATUS_UNKNOWN;

nattype.lookup_time = time(NULL);

do_callbacks();

return;

}

static void do_test1(PurpleSrvResponse *resp, int results, gpointer sdata) {

const char *servername = sdata;

int port = 3478;

if(results) {

servername = resp[0].hostname;

port = resp[0].port;

}

purple_debug_info("stun", "got %d SRV responses, server: %s, port: %d\n",

results, servername, port);

purple_dnsquery_a_account(NULL, servername, port, hbn_cb, NULL);

g_free(resp);

}

static gboolean call_callback(gpointer data) {

StunCallback cb = data;

cb(&nattype);

return FALSE;

}

PurpleStunNatDiscovery *purple_stun_discover(StunCallback cb) {

const char *servername = purple_prefs_get_string("/purple/network/stun_server");

purple_debug_info("stun", "using server %s\n", servername);

if(nattype.status == PURPLE_STUN_STATUS_DISCOVERING) {

if(cb)

callbacks = g_slist_append(callbacks, cb);

return &nattype;

}

if(nattype.status != PURPLE_STUN_STATUS_UNDISCOVERED) {

gboolean use_cached_result = TRUE;

/** Deal with the server name having changed since we did the

lookup */

if (servername && strlen(servername) > 1

&& !purple_strequal(servername, nattype.servername)) {

use_cached_result = FALSE;

}

/* If we don't have a successful status and it has been 5

minutes since we last did a lookup, redo the lookup */

if (nattype.status != PURPLE_STUN_STATUS_DISCOVERED

&& (time(NULL) - nattype.lookup_time) > 300) {

use_cached_result = FALSE;

}

if (use_cached_result) {

if(cb)

purple_timeout_add(10, call_callback, cb);

return &nattype;

}

if(!servername || (strlen(servername) < 2)) {

nattype.status = PURPLE_STUN_STATUS_UNKNOWN;

nattype.lookup_time = time(NULL);

if(cb)

purple_timeout_add(10, call_callback, cb);

return &nattype;

}

nattype.status = PURPLE_STUN_STATUS_DISCOVERING;

nattype.publicip[0] = '\0';

g_free(nattype.servername);

nattype.servername = g_strdup(servername);

callbacks = g_slist_append(callbacks, cb);

purple_srv_resolve_account(NULL, "stun", "udp", servername, do_test1,

(gpointer) servername);

return &nattype;

}

void purple_stun_init() {

purple_prefs_add_string("/purple/network/stun_server", "");

}

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