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feat: Add option to disable DNS lookups in toxcore.
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Allows clients to prevent leaking IP addresses through DNS lookups. This
option, together with disabling Tox UDP, entirely prevents any UDP
packets being sent by toxcore.
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iphydf committed Feb 17, 2024
1 parent 710eb67 commit deae4d9
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Showing 13 changed files with 86 additions and 36 deletions.
8 changes: 4 additions & 4 deletions auto_tests/network_test.c
Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ static void test_addr_resolv_localhost(void)
IP ip;
ip_init(&ip, 0); // ipv6enabled = 0

bool res = addr_resolve_or_parse_ip(ns, localhost, &ip, nullptr);
bool res = addr_resolve_or_parse_ip(ns, localhost, &ip, nullptr, true);

int error = net_error();
char *strerror = net_new_strerror(error);
Expand All @@ -42,14 +42,14 @@ static void test_addr_resolv_localhost(void)
net_ip_ntoa(&ip, &ip_str));

ip_init(&ip, 1); // ipv6enabled = 1
res = addr_resolve_or_parse_ip(ns, localhost, &ip, nullptr);
res = addr_resolve_or_parse_ip(ns, localhost, &ip, nullptr, true);

#if USE_IPV6

int localhost_split = 0;

if (!net_family_is_ipv6(ip.family)) {
res = addr_resolve_or_parse_ip(ns, "ip6-localhost", &ip, nullptr);
res = addr_resolve_or_parse_ip(ns, "ip6-localhost", &ip, nullptr, true);
localhost_split = 1;
}

Expand All @@ -75,7 +75,7 @@ static void test_addr_resolv_localhost(void)
ip.family = net_family_unspec();
IP extra;
ip_reset(&extra);
res = addr_resolve_or_parse_ip(ns, localhost, &ip, &extra);
res = addr_resolve_or_parse_ip(ns, localhost, &ip, &extra, true);
error = net_error();
strerror = net_new_strerror(error);
ck_assert_msg(res, "Resolver failed: %d, %s", error, strerror);
Expand Down
5 changes: 4 additions & 1 deletion other/DHT_bootstrap.c
Original file line number Diff line number Diff line change
Expand Up @@ -228,9 +228,12 @@ int main(int argc, char *argv[])

const uint16_t port = net_htons((uint16_t)port_conv);

// TODO(iphydf): Maybe disable and only use IP addresses?
const bool dns_enabled = true;

uint8_t *bootstrap_key = hex_string_to_bin(argv[argvoffset + 3]);
const bool res = dht_bootstrap_from_address(dht, argv[argvoffset + 1],
ipv6enabled, port, bootstrap_key);
ipv6enabled, dns_enabled, port, bootstrap_key);
free(bootstrap_key);

if (!res) {
Expand Down
5 changes: 4 additions & 1 deletion other/bootstrap_daemon/src/config.c
Original file line number Diff line number Diff line change
Expand Up @@ -377,6 +377,9 @@ bool bootstrap_from_config(const char *cfg_file_path, DHT *dht, bool enable_ipv6
bool address_resolved;
uint8_t *bs_public_key_bin;

// TODO(iphydf): Maybe disable it and only use IP addresses?
const bool dns_enabled = true;

node = config_setting_get_elem(node_list, 0);

if (node == nullptr) {
Expand Down Expand Up @@ -416,7 +419,7 @@ bool bootstrap_from_config(const char *cfg_file_path, DHT *dht, bool enable_ipv6
}

bs_public_key_bin = bootstrap_hex_string_to_bin(bs_public_key);
address_resolved = dht_bootstrap_from_address(dht, bs_address, enable_ipv6, net_htons(bs_port),
address_resolved = dht_bootstrap_from_address(dht, bs_address, enable_ipv6, dns_enabled, net_htons(bs_port),
bs_public_key_bin);
free(bs_public_key_bin);

Expand Down
5 changes: 4 additions & 1 deletion testing/Messenger_test.c
Original file line number Diff line number Diff line change
Expand Up @@ -118,10 +118,13 @@ int main(int argc, char *argv[])
exit(1);
}

// TODO(iphydf): Maybe disable.
const bool dns_enabled = true;

const uint16_t port = net_htons((uint16_t)port_conv);
uint8_t *bootstrap_key = hex_string_to_bin(argv[argvoffset + 3]);
bool res = dht_bootstrap_from_address(m->dht, argv[argvoffset + 1],
ipv6enabled, port, bootstrap_key);
ipv6enabled, dns_enabled, port, bootstrap_key);
free(bootstrap_key);

if (!res) {
Expand Down
4 changes: 2 additions & 2 deletions toxcore/DHT.c
Original file line number Diff line number Diff line change
Expand Up @@ -1840,7 +1840,7 @@ bool dht_bootstrap(DHT *dht, const IP_Port *ip_port, const uint8_t *public_key)
return dht_getnodes(dht, ip_port, public_key, dht->self_public_key);
}

bool dht_bootstrap_from_address(DHT *dht, const char *address, bool ipv6enabled,
bool dht_bootstrap_from_address(DHT *dht, const char *address, bool ipv6enabled, bool dns_enabled,
uint16_t port, const uint8_t *public_key)
{
IP_Port ip_port_v64;
Expand All @@ -1855,7 +1855,7 @@ bool dht_bootstrap_from_address(DHT *dht, const char *address, bool ipv6enabled,
ip_extra = &ip_port_v4.ip;
}

if (addr_resolve_or_parse_ip(dht->ns, address, &ip_port_v64.ip, ip_extra)) {
if (addr_resolve_or_parse_ip(dht->ns, address, &ip_port_v64.ip, ip_extra, dns_enabled)) {
ip_port_v64.port = port;
dht_bootstrap(dht, &ip_port_v64, public_key);

Expand Down
3 changes: 2 additions & 1 deletion toxcore/DHT.h
Original file line number Diff line number Diff line change
Expand Up @@ -404,12 +404,13 @@ bool dht_bootstrap(DHT *dht, const IP_Port *ip_port, const uint8_t *public_key);
* @param address can be a hostname or an IP address (IPv4 or IPv6).
* @param ipv6enabled if false, the resolving sticks STRICTLY to IPv4 addresses.
* Otherwise, the resolving looks for IPv6 addresses first, then IPv4 addresses.
* @param dns_enabled if false, the resolving does not use DNS, only IP addresses are supported.
*
* @retval true if the address could be converted into an IP address
* @retval false otherwise
*/
non_null()
bool dht_bootstrap_from_address(DHT *dht, const char *address, bool ipv6enabled,
bool dht_bootstrap_from_address(DHT *dht, const char *address, bool ipv6enabled, bool dns_enabled,
uint16_t port, const uint8_t *public_key);

/** @brief Start sending packets after DHT loaded_friends_list and loaded_clients_list are set.
Expand Down
2 changes: 2 additions & 0 deletions toxcore/Messenger.h
Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,8 @@ typedef struct Messenger_Options {

Messenger_State_Plugin *state_plugins;
uint8_t state_plugins_length;

bool dns_enabled;
} Messenger_Options;

struct Receipts {
Expand Down
28 changes: 15 additions & 13 deletions toxcore/network.c
Original file line number Diff line number Diff line change
Expand Up @@ -1815,19 +1815,19 @@ bool addr_parse_ip(const char *address, IP *to)
* prefers v6 if `ip.family` was TOX_AF_UNSPEC and both available
* Returns in `*extra` an IPv4 address, if family was TOX_AF_UNSPEC and `*to` is TOX_AF_INET6
*
* @return 0 on failure, `TOX_ADDR_RESOLVE_*` on success.
* @return false on failure, true on success.
*/
non_null(1, 2, 3) nullable(4)
static int addr_resolve(const Network *ns, const char *address, IP *to, IP *extra)
static bool addr_resolve(const Network *ns, const char *address, IP *to, IP *extra)
{
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
if ((true)) {
return 0;
return false;
}
#endif /* FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION */

if (address == nullptr || to == nullptr) {
return 0;
return false;
}

const Family tox_family = to->family;
Expand All @@ -1843,7 +1843,7 @@ static int addr_resolve(const Network *ns, const char *address, IP *to, IP *extr

// Lookup failed.
if (rc != 0) {
return 0;
return false;
}

IP ip4;
Expand Down Expand Up @@ -1907,18 +1907,16 @@ static int addr_resolve(const Network *ns, const char *address, IP *to, IP *extr
}

freeaddrinfo(server);
return result;
return result != 0;
}

bool addr_resolve_or_parse_ip(const Network *ns, const char *address, IP *to, IP *extra)
bool addr_resolve_or_parse_ip(const Network *ns, const char *address, IP *to, IP *extra, bool dns_enabled)
{
if (addr_resolve(ns, address, to, extra) == 0) {
if (!addr_parse_ip(address, to)) {
return false;
}
if (dns_enabled && addr_resolve(ns, address, to, extra)) {
return true;
}

return true;
return addr_parse_ip(address, to);
}

bool net_connect(const Memory *mem, const Logger *log, Socket sock, const IP_Port *ip_port)
Expand Down Expand Up @@ -1974,7 +1972,7 @@ bool net_connect(const Memory *mem, const Logger *log, Socket sock, const IP_Por
return true;
}

int32_t net_getipport(const Memory *mem, const char *node, IP_Port **res, int tox_type)
int32_t net_getipport(const Memory *mem, const char *node, IP_Port **res, int tox_type, bool dns_enabled)
{
assert(node != nullptr);

Expand All @@ -1996,6 +1994,10 @@ int32_t net_getipport(const Memory *mem, const char *node, IP_Port **res, int to
return 1;
}

if (!dns_enabled) {
return -1;
}

#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
if ((true)) {
IP_Port *ip_port = (IP_Port *)mem_alloc(mem, sizeof(IP_Port));
Expand Down
27 changes: 17 additions & 10 deletions toxcore/network.h
Original file line number Diff line number Diff line change
Expand Up @@ -396,21 +396,22 @@ non_null()
void ipport_copy(IP_Port *target, const IP_Port *source);

/**
* Resolves string into an IP address
* @brief Resolves string into an IP address.
*
* @param address a hostname (or something parseable to an IP address)
* @param to to.family MUST be initialized, either set to a specific IP version
* @param[in] address a hostname (or something parseable to an IP address).
* @param[in,out] to to.family MUST be initialized, either set to a specific IP version
* (TOX_AF_INET/TOX_AF_INET6) or to the unspecified TOX_AF_UNSPEC (0), if both
* IP versions are acceptable
* @param extra can be NULL and is only set in special circumstances, see returns
* IP versions are acceptable.
* @param[in] extra can be NULL and is only set in special circumstances, see returns.
* @param[in] dns_enabled if false, DNS resolution is skipped.
*
* Returns in `*to` a matching address (IPv6 or IPv4)
* Returns in `*extra`, if not NULL, an IPv4 address, if `to->family` was TOX_AF_UNSPEC
* Returns in `*to` a matching address (IPv6 or IPv4).
* Returns in `*extra`, if not NULL, an IPv4 address, if `to->family` was `TOX_AF_UNSPEC`.
*
* @return true on success, false on failure
*/
non_null(1, 2, 3) nullable(4)
bool addr_resolve_or_parse_ip(const Network *ns, const char *address, IP *to, IP *extra);
bool addr_resolve_or_parse_ip(const Network *ns, const char *address, IP *to, IP *extra, bool dns_enabled);

/** @brief Function to receive data, ip and port of sender is put into ip_port.
* Packet data is put into data.
Expand Down Expand Up @@ -510,14 +511,20 @@ bool net_connect(const Memory *mem, const Logger *log, Socket sock, const IP_Por
* address that can be specified by calling `net_connect()`, the port is ignored.
*
* Skip all addresses with socktype != type (use type = -1 to get all addresses)
* To correctly deallocate array memory use `net_freeipport()`
* To correctly deallocate array memory use `net_freeipport()`.
*
* @param mem Memory allocator.
* @param node The node parameter identifies the host or service on which to connect.
* @param[out] res An array of IP_Port structures will be allocated into this pointer.
* @param tox_type The type of socket to use (stream or datagram), only relevant for DNS lookups.
* @param dns_enabled If false, DNS resolution is skipped, when passed a hostname, this function will return an error.
*
* @return number of elements in res array.
* @retval 0 if res array empty.
* @retval -1 on error.
*/
non_null()
int32_t net_getipport(const Memory *mem, const char *node, IP_Port **res, int tox_type);
int32_t net_getipport(const Memory *mem, const char *node, IP_Port **res, int tox_type, bool dns_enabled);

/** Deallocates memory allocated by net_getipport */
non_null(1) nullable(2)
Expand Down
7 changes: 5 additions & 2 deletions toxcore/tox.c
Original file line number Diff line number Diff line change
Expand Up @@ -752,6 +752,8 @@ Tox *tox_new(const struct Tox_Options *options, Tox_Err_New *error)

Messenger_Options m_options = {false};

m_options.dns_enabled = tox_options_get_dns_enabled(opts);

bool load_savedata_sk = false;
bool load_savedata_tox = false;

Expand Down Expand Up @@ -855,9 +857,10 @@ Tox *tox_new(const struct Tox_Options *options, Tox_Err_New *error)
}

const char *const proxy_host = tox_options_get_proxy_host(opts);
const bool dns_enabled = tox_options_get_dns_enabled(opts);

if (proxy_host == nullptr
|| !addr_resolve_or_parse_ip(tox->sys.ns, proxy_host, &m_options.proxy_info.ip_port.ip, nullptr)) {
|| !addr_resolve_or_parse_ip(tox->sys.ns, proxy_host, &m_options.proxy_info.ip_port.ip, nullptr, dns_enabled)) {
SET_ERROR_PARAMETER(error, TOX_ERR_NEW_PROXY_BAD_HOST);
// TODO(irungentoo): TOX_ERR_NEW_PROXY_NOT_FOUND if domain.
mem_delete(sys->mem, tox);
Expand Down Expand Up @@ -1108,7 +1111,7 @@ static int32_t resolve_bootstrap_node(Tox *tox, const char *host, uint16_t port,
return -1;
}

const int32_t count = net_getipport(tox->sys.mem, host, root, TOX_SOCK_DGRAM);
const int32_t count = net_getipport(tox->sys.mem, host, root, TOX_SOCK_DGRAM, tox->m->options.dns_enabled);

if (count < 1) {
LOGGER_DEBUG(tox->m->log, "could not resolve bootstrap node '%s'", host);
Expand Down
17 changes: 17 additions & 0 deletions toxcore/tox.h
Original file line number Diff line number Diff line change
Expand Up @@ -689,6 +689,19 @@ struct Tox_Options {
* Default: false.
*/
bool experimental_groups_persistence;

/**
* @brief Allow passing hostnames to the bootstrap function and proxy host option.
*
* If this is set to false, the library will not attempt to resolve hostnames.
* This is useful for clients that want to resolve hostnames themselves and
* pass the resolved IP addresses to the library (e.g. in case it wants to use Tor).
* Passing hostnames will result in a TOX_ERR_BOOTSTRAP_BAD_HOST error if this is
* set to false.
*
* Default: true. May become false in the future (0.3.0).
*/
bool dns_enabled;
};

bool tox_options_get_ipv6_enabled(const Tox_Options *options);
Expand Down Expand Up @@ -767,6 +780,10 @@ bool tox_options_get_experimental_groups_persistence(const Tox_Options *options)

void tox_options_set_experimental_groups_persistence(Tox_Options *options, bool experimental_groups_persistence);

bool tox_options_get_dns_enabled(const Tox_Options *options);

void tox_options_set_dns_enabled(Tox_Options *options, bool dns_enabled);

/**
* @brief Initialises a Tox_Options object with the default options.
*
Expand Down
9 changes: 9 additions & 0 deletions toxcore/tox_api.c
Original file line number Diff line number Diff line change
Expand Up @@ -282,6 +282,14 @@ void tox_options_set_experimental_groups_persistence(
{
options->experimental_groups_persistence = experimental_groups_persistence;
}
bool tox_options_get_dns_enabled(const Tox_Options *options)
{
return options->dns_enabled;
}
void tox_options_set_dns_enabled(Tox_Options *options, bool dns_enabled)
{
options->dns_enabled = dns_enabled;
}

const uint8_t *tox_options_get_savedata_data(const Tox_Options *options)
{
Expand All @@ -307,6 +315,7 @@ void tox_options_default(Tox_Options *options)
tox_options_set_dht_announcements_enabled(options, true);
tox_options_set_experimental_thread_safety(options, false);
tox_options_set_experimental_groups_persistence(options, false);
tox_options_set_dns_enabled(options, true);
}
}

Expand Down
2 changes: 1 addition & 1 deletion toxcore/tox_private.c
Original file line number Diff line number Diff line change
Expand Up @@ -124,7 +124,7 @@ bool tox_dht_get_nodes(const Tox *tox, const uint8_t *public_key, const char *ip

IP_Port *root;

const int32_t count = net_getipport(tox->sys.mem, ip, &root, TOX_SOCK_DGRAM);
const int32_t count = net_getipport(tox->sys.mem, ip, &root, TOX_SOCK_DGRAM, tox->m->options.dns_enabled);

if (count < 1) {
SET_ERROR_PARAMETER(error, TOX_ERR_DHT_GET_NODES_BAD_IP);
Expand Down

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