feat: Add option to disable DNS lookups in toxcore.

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.

Author: iphydf

auto_tests/network_test.c

@@ -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);
@@ -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;
     }
 
@@ -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);

other/DHT_bootstrap.c

@@ -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) {

other/bootstrap_daemon/src/config.c

@@ -390,6 +390,9 @@ 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) {
@@ -429,7 +432,7 @@ 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);
 

testing/Messenger_test.c

@@ -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) {

toxcore/DHT.c

@@ -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;
@@ -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);
 

toxcore/DHT.h

@@ -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.

toxcore/Messenger.h

@@ -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 {

toxcore/network.c

@@ -1826,19 +1826,19 @@ 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;
@@ -1854,7 +1854,7 @@ 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;
@@ -1918,18 +1918,16 @@ 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 Network *ns, const Memory *mem, const Logger *log, Socket sock, const IP_Port *ip_port)
@@ -1984,7 +1982,7 @@ bool net_connect(const Network *ns, const Memory *mem, const Logger *log, Socket
     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);
 
@@ -2006,6 +2004,10 @@ 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));

toxcore/network.h

@@ -398,21 +398,22 @@ 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[out] 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.
@@ -512,14 +513,20 @@ bool net_connect(const Network *ns, const Memory *mem, const Logger *log, Socket
  * 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)

toxcore/tox.c

@@ -752,6 +752,8 @@ static Tox *tox_new_system(const struct Tox_Options *options, Tox_Err_New *error
 
     Messenger_Options m_options = {false};
 
+    m_options.dns_enabled = !tox_options_get_experimental_disable_dns(opts);
+
     bool load_savedata_sk = false;
     bool load_savedata_tox = false;
 
@@ -855,9 +857,10 @@ static Tox *tox_new_system(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_experimental_disable_dns(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);
@@ -1139,7 +1142,7 @@ 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);