device: add a nm_device_resolve_address()
The new function resolve an address via DNS, first by using systemd-resolved (disabling synthesized results) and then by spawning the daemon helper. Trying systemd-resolved via D-Bus before spawning the helper is important to get a correct result. Suppose that resolv.conf points to the local stub listener at 127.0.0.53; if NM only spawns the helper, the helper will query the local systemd-resolved which could return a synthesized result. Therefore, we first query systemd-resolved with NO_SYNTHESIZE and then, in case of error, we spawn the helper.
This commit is contained in:
Beniamino Galvani
@@ -1,8 +1,11 @@
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/* SPDX-License-Identifier: GPL-2.0-or-later */
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#include "src/core/nm-default-daemon.h"
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#include "src/core/dns/nm-dns-manager.h"
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#include "src/core/dns/nm-dns-systemd-resolved.h"
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#include "nm-device-utils.h"
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#include "nm-core-utils.h"
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/*****************************************************************************/
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@@ -152,3 +155,202 @@ NM_UTILS_LOOKUP_STR_DEFINE(nm_device_ip_state_to_str,
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NM_UTILS_LOOKUP_STR_ITEM(NM_DEVICE_IP_STATE_CONF, "conf"),
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NM_UTILS_LOOKUP_STR_ITEM(NM_DEVICE_IP_STATE_DONE, "done"),
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NM_UTILS_LOOKUP_STR_ITEM(NM_DEVICE_IP_STATE_FAIL, "fail"), );
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/*****************************************************************************/
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#define SD_RESOLVED_DNS (1UL << 0)
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/* Don't answer request from locally synthesized records (which includes /etc/hosts) */
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#define SD_RESOLVED_NO_SYNTHESIZE (1UL << 11)
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typedef struct {
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int addr_family;
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NMIPAddr address;
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gulong cancellable_id;
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GTask * task;
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NMDnsSystemdResolvedResolveHandle *resolved_handle;
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} ResolveAddrInfo;
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#define _NMLOG_PREFIX_NAME "resolve-addr"
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#define _NMLOG_DOMAIN LOGD_CORE
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#define _NMLOG2(level, info, ...) \
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G_STMT_START \
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{ \
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if (nm_logging_enabled((level), (_NMLOG_DOMAIN))) { \
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ResolveAddrInfo *_info = (info); \
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char _addr_str[NM_UTILS_INET_ADDRSTRLEN]; \
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\
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_nm_log((level), \
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(_NMLOG_DOMAIN), \
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0, \
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NULL, \
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NULL, \
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_NMLOG_PREFIX_NAME "[" NM_HASH_OBFUSCATE_PTR_FMT \
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",%s]: " _NM_UTILS_MACRO_FIRST(__VA_ARGS__), \
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NM_HASH_OBFUSCATE_PTR(_info), \
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nm_utils_inet_ntop(_info->addr_family, &_info->address, _addr_str) \
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_NM_UTILS_MACRO_REST(__VA_ARGS__)); \
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} \
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} \
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G_STMT_END
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static void
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resolve_addr_info_free(ResolveAddrInfo *info)
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{
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nm_assert(info->cancellable_id == 0);
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nm_assert(!info->resolved_handle);
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g_object_unref(info->task);
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g_free(info);
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}
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static void
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resolve_addr_complete(ResolveAddrInfo *info, char *hostname_take, GError *error_take)
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{
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nm_assert(!!hostname_take != !!error_take);
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nm_clear_g_cancellable_disconnect(g_task_get_cancellable(info->task), &info->cancellable_id);
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if (error_take)
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g_task_return_error(info->task, error_take);
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else
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g_task_return_pointer(info->task, hostname_take, g_free);
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resolve_addr_info_free(info);
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}
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static void
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resolve_addr_helper_cb(GObject *source, GAsyncResult *result, gpointer user_data)
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{
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ResolveAddrInfo *info = user_data;
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gs_free_error GError *error = NULL;
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gs_free char * output = NULL;
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output = nm_utils_spawn_helper_finish(result, &error);
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if (nm_utils_error_is_cancelled(error))
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return;
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_LOG2D(info, "helper returned hostname '%s'", output);
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resolve_addr_complete(info, g_steal_pointer(&output), g_steal_pointer(&error));
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}
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static void
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resolve_addr_spawn_helper(ResolveAddrInfo *info)
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{
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char addr_str[NM_UTILS_INET_ADDRSTRLEN];
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nm_utils_inet_ntop(info->addr_family, &info->address, addr_str);
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_LOG2D(info, "start lookup via nm-daemon-helper");
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nm_utils_spawn_helper(NM_MAKE_STRV("resolve-address", addr_str),
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g_task_get_cancellable(info->task),
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resolve_addr_helper_cb,
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info);
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}
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static void
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resolve_addr_resolved_cb(NMDnsSystemdResolved * resolved,
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NMDnsSystemdResolvedResolveHandle * handle,
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const NMDnsSystemdResolvedAddressResult *names,
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guint names_len,
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guint64 flags,
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GError * error,
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gpointer user_data)
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{
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ResolveAddrInfo *info = user_data;
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info->resolved_handle = NULL;
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if (nm_utils_error_is_cancelled(error))
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return;
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if (error) {
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gs_free char *dbus_error = NULL;
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_LOG2D(info, "error resolving via systemd-resolved: %s", error->message);
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dbus_error = g_dbus_error_get_remote_error(error);
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if (nm_streq0(dbus_error, "org.freedesktop.resolve1.DnsError.NXDOMAIN")) {
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resolve_addr_complete(info, NULL, g_error_copy(error));
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return;
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}
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resolve_addr_spawn_helper(info);
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return;
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}
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if (names_len == 0) {
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_LOG2D(info, "systemd-resolved returned no result");
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resolve_addr_complete(info, g_strdup(""), NULL);
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return;
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}
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_LOG2D(info, "systemd-resolved returned hostname '%s'", names[0].name);
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resolve_addr_complete(info, g_strdup(names[0].name), NULL);
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}
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static void
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resolve_addr_cancelled(GObject *object, gpointer user_data)
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{
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ResolveAddrInfo *info = user_data;
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GError * error = NULL;
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nm_clear_g_signal_handler(g_task_get_cancellable(info->task), &info->cancellable_id);
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nm_clear_pointer(&info->resolved_handle, nm_dns_systemd_resolved_resolve_cancel);
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nm_utils_error_set_cancelled(&error, FALSE, NULL);
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resolve_addr_complete(info, NULL, error);
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}
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void
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nm_device_resolve_address(int addr_family,
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gconstpointer address,
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GCancellable * cancellable,
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GAsyncReadyCallback callback,
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gpointer cb_data)
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{
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ResolveAddrInfo * info;
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NMDnsSystemdResolved *resolved;
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info = g_new(ResolveAddrInfo, 1);
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*info = (ResolveAddrInfo){
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.task = nm_g_task_new(NULL, cancellable, nm_device_resolve_address, callback, cb_data),
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.addr_family = addr_family,
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.address = nm_ip_addr_init(addr_family, address),
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};
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if (cancellable) {
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gulong signal_id;
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signal_id =
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g_cancellable_connect(cancellable, G_CALLBACK(resolve_addr_cancelled), info, NULL);
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if (signal_id == 0) {
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/* the request is already cancelled. Return. */
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return;
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}
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info->cancellable_id = signal_id;
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}
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resolved = (NMDnsSystemdResolved *) nm_dns_manager_get_systemd_resolved(nm_dns_manager_get());
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if (resolved) {
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_LOG2D(info, "start lookup via systemd-resolved");
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info->resolved_handle =
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nm_dns_systemd_resolved_resolve_address(resolved,
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0,
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addr_family,
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address,
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SD_RESOLVED_DNS | SD_RESOLVED_NO_SYNTHESIZE,
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20000,
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resolve_addr_resolved_cb,
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info);
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return;
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}
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resolve_addr_spawn_helper(info);
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}
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char *
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nm_device_resolve_address_finish(GAsyncResult *result, GError **error)
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{
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GTask *task = G_TASK(result);
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nm_assert(nm_g_task_is_valid(result, NULL, nm_device_resolve_address));
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return g_task_propagate_pointer(task, error);
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}
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@@ -85,4 +85,14 @@ const char *nm_device_ip_state_to_str(NMDeviceIPState ip_state);
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/*****************************************************************************/
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/*****************************************************************************/
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void nm_device_resolve_address(int addr_family,
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gconstpointer address,
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GCancellable * cancellable,
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GAsyncReadyCallback callback,
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gpointer cb_data);
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char *nm_device_resolve_address_finish(GAsyncResult *result, GError **error);
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#endif /* __DEVICES_NM_DEVICE_UTILS_H__ */
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