/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Copyright (C) 2011 Thomas Bechtold <thomasbechtold@jpberlin.de>
 * Copyright (C) 2011 Dan Williams <dcbw@redhat.com>
 * Copyright (C) 2016 - 2018 Red Hat, Inc.
 */

#include "src/core/nm-default-daemon.h"

#include "nm-connectivity.h"

#if WITH_CONCHECK
#include <curl/curl.h>
#endif
#include <linux/rtnetlink.h>

#include "c-list/src/c-list.h"
#include "libnm-glib-aux/nm-str-buf.h"
#include "libnm-platform/nmp-object.h"
#include "libnm-core-intern/nm-core-internal.h"
#include "nm-config.h"
#include "NetworkManagerUtils.h"
#include "nm-dbus-manager.h"
#include "dns/nm-dns-manager.h"

#define HEADER_STATUS_ONLINE "X-NetworkManager-Status: online\r\n"

/*****************************************************************************/

static NM_UTILS_LOOKUP_STR_DEFINE(_state_to_string,
                                  int /*NMConnectivityState*/,
                                  NM_UTILS_LOOKUP_DEFAULT_WARN("???"),
                                  NM_UTILS_LOOKUP_STR_ITEM(NM_CONNECTIVITY_UNKNOWN, "UNKNOWN"),
                                  NM_UTILS_LOOKUP_STR_ITEM(NM_CONNECTIVITY_NONE, "NONE"),
                                  NM_UTILS_LOOKUP_STR_ITEM(NM_CONNECTIVITY_LIMITED, "LIMITED"),
                                  NM_UTILS_LOOKUP_STR_ITEM(NM_CONNECTIVITY_PORTAL, "PORTAL"),
                                  NM_UTILS_LOOKUP_STR_ITEM(NM_CONNECTIVITY_FULL, "FULL"),

                                  NM_UTILS_LOOKUP_STR_ITEM(NM_CONNECTIVITY_ERROR, "ERROR"),
                                  NM_UTILS_LOOKUP_STR_ITEM(NM_CONNECTIVITY_FAKE, "FAKE"),
                                  NM_UTILS_LOOKUP_STR_ITEM(NM_CONNECTIVITY_CANCELLED, "CANCELLED"),
                                  NM_UTILS_LOOKUP_STR_ITEM(NM_CONNECTIVITY_DISPOSING,
                                                           "DISPOSING"), );

const char *
nm_connectivity_state_to_string(NMConnectivityState state)
{
    return _state_to_string(state);
}

/*****************************************************************************/

typedef struct {
    guint ref_count;
    char *uri;
    char *host;
    char *port;
    char *response;
} ConConfig;

struct _NMConnectivityCheckHandle {
    CList                       handles_lst;
    NMConnectivity             *self;
    NMConnectivityCheckCallback callback;
    gpointer                    user_data;

    char *ifspec;

    const char *completed_log_message;
    char       *completed_log_message_free;

#if WITH_CONCHECK
    struct {
        ConConfig *con_config;

        GCancellable      *resolve_cancellable;
        CURLM             *curl_mhandle;
        CURL              *curl_ehandle;
        struct curl_slist *request_headers;
        struct curl_slist *hosts;

        gsize response_good_cnt;

        guint curl_timer;
        int   ch_ifindex;
    } concheck;
#endif

    guint64 request_counter;

    int addr_family;

    GSource *timeout_source;

    NMConnectivityState completed_state;
    const char         *completed_reason;
};

enum {
    CONFIG_CHANGED,

    LAST_SIGNAL
};

static guint signals[LAST_SIGNAL] = {0};

typedef struct {
    CList      handles_lst_head;
    CList      completed_handles_lst_head;
    NMConfig  *config;
    ConConfig *con_config;
    guint      interval;

    bool enabled : 1;
    bool uri_valid : 1;
} NMConnectivityPrivate;

struct _NMConnectivity {
    GObject               parent;
    NMConnectivityPrivate _priv;
};

struct _NMConnectivityClass {
    GObjectClass parent;
};

G_DEFINE_TYPE(NMConnectivity, nm_connectivity, G_TYPE_OBJECT)

#define NM_CONNECTIVITY_GET_PRIVATE(self) _NM_GET_PRIVATE(self, NMConnectivity, NM_IS_CONNECTIVITY)

NM_DEFINE_SINGLETON_GETTER(NMConnectivity, nm_connectivity_get, NM_TYPE_CONNECTIVITY);

/*****************************************************************************/

#define _NMLOG_DOMAIN      LOGD_CONCHECK
#define _NMLOG(level, ...) __NMLOG_DEFAULT(level, _NMLOG_DOMAIN, "connectivity", __VA_ARGS__)

#define _NMLOG2_DOMAIN LOGD_CONCHECK
#define _NMLOG2(level, ...)                                                      \
    G_STMT_START                                                                 \
    {                                                                            \
        const NMLogLevel __level = (level);                                      \
                                                                                 \
        if (nm_logging_enabled(__level, _NMLOG2_DOMAIN)) {                       \
            _nm_log(__level,                                                     \
                    _NMLOG2_DOMAIN,                                              \
                    0,                                                           \
                    (cb_data->ifspec ? &cb_data->ifspec[3] : NULL),              \
                    NULL,                                                        \
                    "connectivity: (%s,IPv%c,%" G_GUINT64_FORMAT                 \
                    ") " _NM_UTILS_MACRO_FIRST(__VA_ARGS__),                     \
                    (cb_data->ifspec ? &cb_data->ifspec[3] : ""),                \
                    nm_utils_addr_family_to_char(cb_data->addr_family),          \
                    cb_data->request_counter _NM_UTILS_MACRO_REST(__VA_ARGS__)); \
        }                                                                        \
    }                                                                            \
    G_STMT_END

/*****************************************************************************/

#if WITH_CONCHECK
static ConConfig *
_con_config_ref(ConConfig *con_config)
{
    if (con_config) {
        nm_assert(con_config->ref_count > 0);
        ++con_config->ref_count;
    }
    return con_config;
}
#endif

static void
_con_config_unref(ConConfig *con_config)
{
    if (!con_config)
        return;

    nm_assert(con_config->ref_count > 0);

    if (--con_config->ref_count != 0)
        return;

    g_free(con_config->uri);
    g_free(con_config->host);
    g_free(con_config->port);
    g_free(con_config->response);
    g_slice_free(ConConfig, con_config);
}

#if WITH_CONCHECK
static const char *
_con_config_get_response(const ConConfig *con_config)
{
    return con_config->response ?: NM_CONFIG_DEFAULT_CONNECTIVITY_RESPONSE;
}
#endif

/*****************************************************************************/

static void
cb_data_complete(NMConnectivityCheckHandle *cb_data,
                 NMConnectivityState        state,
                 const char                *log_message)
{
    NMConnectivity *self;

    nm_assert(cb_data);
    nm_assert(NM_IS_CONNECTIVITY(cb_data->self));
    nm_assert(cb_data->callback);
    nm_assert(state != NM_CONNECTIVITY_UNKNOWN);
    nm_assert(log_message);

    self = cb_data->self;

    /* mark the handle as completing. After this point, nm_connectivity_check_cancel()
     * is no longer possible. */
    cb_data->self = NULL;

    c_list_unlink_stale(&cb_data->handles_lst);

#if WITH_CONCHECK
    if (cb_data->concheck.curl_ehandle) {
        /* Contrary to what cURL manual claim it is *not* safe to remove
         * the easy handle "at any moment"; specifically it's not safe to
         * remove *any* handle from within a libcurl callback. That is
         * why we queue completed handles in this case.
         *
         * cb_data_complete() is however only called *not* from within a
         * libcurl callback. So, this is fine. */
        curl_easy_setopt(cb_data->concheck.curl_ehandle, CURLOPT_WRITEFUNCTION, NULL);
        curl_easy_setopt(cb_data->concheck.curl_ehandle, CURLOPT_WRITEDATA, NULL);
        curl_easy_setopt(cb_data->concheck.curl_ehandle, CURLOPT_HEADERFUNCTION, NULL);
        curl_easy_setopt(cb_data->concheck.curl_ehandle, CURLOPT_HEADERDATA, NULL);
        curl_easy_setopt(cb_data->concheck.curl_ehandle, CURLOPT_PRIVATE, NULL);
        curl_easy_setopt(cb_data->concheck.curl_ehandle, CURLOPT_HTTPHEADER, NULL);

        curl_multi_remove_handle(cb_data->concheck.curl_mhandle, cb_data->concheck.curl_ehandle);
        curl_easy_cleanup(cb_data->concheck.curl_ehandle);
        curl_multi_cleanup(cb_data->concheck.curl_mhandle);

        curl_slist_free_all(cb_data->concheck.request_headers);
        curl_slist_free_all(cb_data->concheck.hosts);
    }
    nm_clear_g_source(&cb_data->concheck.curl_timer);
    nm_clear_g_cancellable(&cb_data->concheck.resolve_cancellable);
#endif

    nm_clear_g_source_inst(&cb_data->timeout_source);

    _LOG2D("check completed: %s; %s", nm_connectivity_state_to_string(state), log_message);

    cb_data->callback(self, cb_data, state, cb_data->user_data);

    /* Note: self might be a danling pointer at this point. It must not be used
     * after this point, and all callers must either take a reference first, or
     * not use the self pointer too. */

#if WITH_CONCHECK
    _con_config_unref(cb_data->concheck.con_config);
#endif
    g_free(cb_data->ifspec);
    if (cb_data->completed_log_message_free)
        g_free(cb_data->completed_log_message_free);
    g_slice_free(NMConnectivityCheckHandle, cb_data);
}

/*****************************************************************************/

#if WITH_CONCHECK

static void
cb_data_queue_completed(NMConnectivityCheckHandle *cb_data,
                        NMConnectivityState        state,
                        const char                *log_message_static,
                        char                      *log_message_take /* take */)
{
    nm_assert(cb_data);
    nm_assert(NM_IS_CONNECTIVITY(cb_data->self));
    nm_assert(state != NM_CONNECTIVITY_UNKNOWN);
    nm_assert(log_message_static || log_message_take);
    nm_assert(cb_data->completed_state == NM_CONNECTIVITY_UNKNOWN);
    nm_assert(!cb_data->completed_log_message);
    nm_assert(c_list_contains(&NM_CONNECTIVITY_GET_PRIVATE(cb_data->self)->handles_lst_head,
                              &cb_data->handles_lst));

    cb_data->completed_state            = state;
    cb_data->completed_log_message      = log_message_static ?: log_message_take;
    cb_data->completed_log_message_free = log_message_take;

    c_list_unlink_stale(&cb_data->handles_lst);
    c_list_link_tail(&NM_CONNECTIVITY_GET_PRIVATE(cb_data->self)->completed_handles_lst_head,
                     &cb_data->handles_lst);
}

static void
_complete_queued(NMConnectivity *self)
{
    NMConnectivity            *self_keep_alive = NULL;
    NMConnectivityPrivate     *priv            = NM_CONNECTIVITY_GET_PRIVATE(self);
    NMConnectivityCheckHandle *cb_data;

    while ((cb_data = c_list_first_entry(&priv->completed_handles_lst_head,
                                         NMConnectivityCheckHandle,
                                         handles_lst))) {
        if (!self_keep_alive)
            self_keep_alive = g_object_ref(self);
        cb_data_complete(cb_data, cb_data->completed_state, cb_data->completed_log_message);
    }
    nm_g_object_unref(self_keep_alive);
}

static gboolean
_con_curl_check_connectivity(CURLM *mhandle, int sockfd, int ev_bitmask)
{
    NMConnectivityCheckHandle *cb_data;
    CURLMsg                   *msg;
    int                        m_left;
    long                       response_code;
    CURLMcode                  ret;
    int                        running_handles;
    gboolean                   success = TRUE;

    ret = curl_multi_socket_action(mhandle, sockfd, ev_bitmask, &running_handles);
    if (ret != CURLM_OK) {
        _LOGD("connectivity check failed: (%d) %s", ret, curl_multi_strerror(ret));
        success = FALSE;
    }

    while ((msg = curl_multi_info_read(mhandle, &m_left))) {
        const char *response;
        CURLcode    eret;

        if (msg->msg != CURLMSG_DONE)
            continue;

        /* Here we have completed a session. Check easy session result. */
        eret = curl_easy_getinfo(msg->easy_handle, CURLINFO_PRIVATE, (char **) &cb_data);
        if (eret != CURLE_OK) {
            _LOGD("curl cannot extract cb_data for easy handle, skipping msg: (%d) %s",
                  eret,
                  curl_easy_strerror(eret));
            success = FALSE;
            continue;
        }

        nm_assert(cb_data);
        nm_assert(NM_IS_CONNECTIVITY(cb_data->self));

        if (cb_data->completed_state != NM_CONNECTIVITY_UNKNOWN) {
            /* callback was already invoked earlier. Nothing to do. */
            continue;
        }

        if (msg->data.result != CURLE_OK) {
            cb_data_queue_completed(cb_data,
                                    NM_CONNECTIVITY_LIMITED,
                                    NULL,
                                    g_strdup_printf("check failed: (%d) %s",
                                                    msg->data.result,
                                                    curl_easy_strerror(msg->data.result)));
            continue;
        }

        response = _con_config_get_response(cb_data->concheck.con_config);

        if (response[0] == '\0'
            && (curl_easy_getinfo(msg->easy_handle, CURLINFO_RESPONSE_CODE, &response_code)
                == CURLE_OK)) {
            if (response_code == 204) {
                /* We expected an empty response, and we got a 204 response code (no content).
                 * We may or may not have received any content (we would ignore it).
                 * Anyway, the response_code 204 means we are good. */
                cb_data_queue_completed(cb_data,
                                        NM_CONNECTIVITY_FULL,
                                        "no content, as expected",
                                        NULL);
                continue;
            }

            if (response_code == 200 && cb_data->concheck.response_good_cnt == 0) {
                /* we expected no response, and indeed we got an empty reply (with status code 200) */
                cb_data_queue_completed(cb_data,
                                        NM_CONNECTIVITY_FULL,
                                        "empty response, as expected",
                                        NULL);
                continue;
            }
        }

        /* If we get here, it means that easy_write_cb() didn't read enough
         * bytes to be able to do a match, or that we were asking for no content
         * (204 response code) and we actually got some. Either way, that is
         * an indication of a captive portal */
        cb_data_queue_completed(cb_data, NM_CONNECTIVITY_PORTAL, "unexpected short response", NULL);
    }

    /* if we return a failure, we don't know what went wrong. It's likely serious, because
     * a failure here is not expected. Return FALSE, so that we stop polling the file descriptor.
     * Worst case, this leaves the pending connectivity check unhandled, until our regular
     * time-out kicks in. */
    return success;
}

static gboolean
_con_curl_timeout_cb(gpointer user_data)
{
    NMConnectivityCheckHandle *cb_data = user_data;

    _con_curl_check_connectivity(cb_data->concheck.curl_mhandle, CURL_SOCKET_TIMEOUT, 0);
    _complete_queued(cb_data->self);
    return G_SOURCE_CONTINUE;
}

static int
multi_timer_cb(CURLM *multi, long timeout_msec, void *userdata)
{
    NMConnectivityCheckHandle *cb_data = userdata;

    nm_clear_g_source(&cb_data->concheck.curl_timer);
    if (timeout_msec != -1)
        cb_data->concheck.curl_timer = g_timeout_add(timeout_msec, _con_curl_timeout_cb, cb_data);
    return 0;
}

typedef struct {
    NMConnectivityCheckHandle *cb_data;

    GSource *source;

    /* this is a very simplistic weak-pointer. If ConCurlSockData gets
     * destroyed, it will set *destroy_notify to TRUE.
     *
     * _con_curl_socketevent_cb() uses this to detect whether it can
     * safely access @fdp after _con_curl_check_connectivity(). */
    gboolean *destroy_notify;

} ConCurlSockData;

static gboolean
_con_curl_socketevent_cb(int fd, GIOCondition condition, gpointer user_data)
{
    ConCurlSockData           *fdp           = user_data;
    NMConnectivityCheckHandle *cb_data       = fdp->cb_data;
    int                        action        = 0;
    gboolean                   fdp_destroyed = FALSE;
    gboolean                   success;

    if (condition & G_IO_IN)
        action |= CURL_CSELECT_IN;
    if (condition & G_IO_OUT)
        action |= CURL_CSELECT_OUT;
    if (condition & G_IO_ERR)
        action |= CURL_CSELECT_ERR;

    nm_assert(!fdp->destroy_notify);
    fdp->destroy_notify = &fdp_destroyed;

    success = _con_curl_check_connectivity(cb_data->concheck.curl_mhandle, fd, action);

    if (fdp_destroyed) {
        /* hups. fdp got invalidated during _con_curl_check_connectivity(). That's fine,
         * just don't touch it. */
    } else {
        nm_assert(fdp->destroy_notify == &fdp_destroyed);
        fdp->destroy_notify = NULL;
        if (!success)
            nm_clear_g_source_inst(&fdp->source);
    }

    _complete_queued(cb_data->self);

    return G_SOURCE_CONTINUE;
}

static int
multi_socket_cb(CURL *e_handle, curl_socket_t fd, int what, void *userdata, void *socketp)
{
    NMConnectivityCheckHandle *cb_data = userdata;
    ConCurlSockData           *fdp     = socketp;

    (void) _NM_ENSURE_TYPE(int, fd);

    if (what == CURL_POLL_REMOVE) {
        if (fdp) {
            if (fdp->destroy_notify)
                *fdp->destroy_notify = TRUE;
            nm_clear_g_source_inst(&fdp->source);
            curl_multi_assign(cb_data->concheck.curl_mhandle, fd, NULL);
            g_slice_free(ConCurlSockData, fdp);
        }
    } else {
        GIOCondition condition;

        if (!fdp) {
            fdp  = g_slice_new(ConCurlSockData);
            *fdp = (ConCurlSockData){
                .cb_data = cb_data,
            };
            curl_multi_assign(cb_data->concheck.curl_mhandle, fd, fdp);
        } else
            nm_clear_g_source_inst(&fdp->source);

        if (what == CURL_POLL_IN)
            condition = G_IO_IN;
        else if (what == CURL_POLL_OUT)
            condition = G_IO_OUT;
        else if (what == CURL_POLL_INOUT)
            condition = G_IO_IN | G_IO_OUT;
        else
            condition = 0;

        if (condition)
            fdp->source = nm_g_unix_fd_add_source(fd, condition, _con_curl_socketevent_cb, fdp);
    }

    return CURLM_OK;
}

static size_t
easy_header_cb(char *buffer, size_t size, size_t nitems, void *userdata)
{
    NMConnectivityCheckHandle *cb_data = userdata;
    size_t                     len     = size * nitems;

    if (cb_data->completed_state != NM_CONNECTIVITY_UNKNOWN) {
        /* already completed. */
        return 0;
    }

    if (len >= sizeof(HEADER_STATUS_ONLINE) - 1
        && !g_ascii_strncasecmp(buffer, HEADER_STATUS_ONLINE, sizeof(HEADER_STATUS_ONLINE) - 1)) {
        cb_data_queue_completed(cb_data, NM_CONNECTIVITY_FULL, "status header found", NULL);
        return 0;
    }

    return len;
}

static size_t
easy_write_cb(void *buffer, size_t size, size_t nmemb, void *userdata)
{
    NMConnectivityCheckHandle *cb_data = userdata;
    size_t                     len     = size * nmemb;
    size_t                     response_len;
    size_t                     check_len;
    const char                *response;

    if (cb_data->completed_state != NM_CONNECTIVITY_UNKNOWN) {
        /* already completed. */
        return 0;
    }

    if (len == 0) {
        /* no data. That can happen, it's fine. */
        return len;
    }

    response = _con_config_get_response(cb_data->concheck.con_config);

    if (response[0] == '\0') {
        /* no response expected. We are however graceful and accept any
         * extra response that we might receive. We determine the empty
         * response based on the status code 204.
         *
         * Continue receiving... */
        cb_data->concheck.response_good_cnt += len;

        if (cb_data->concheck.response_good_cnt > (gsize) (100 * 1024)) {
            /* we expect an empty response. We accept either
             * 1) status code 204 and any response
             * 2) status code 200 and an empty response.
             *
             * Here, we want to continue receiving data, to see whether we have
             * case 1). Arguably, the server shouldn't send us 204 with a non-empty
             * response, but we accept that also with a non-empty response, so
             * keep receiving.
             *
             * However, if we get an excessive amount of data, we put a stop on it
             * and fail. */
            cb_data_queue_completed(cb_data,
                                    NM_CONNECTIVITY_PORTAL,
                                    "unexpected non-empty response",
                                    NULL);
            return 0;
        }

        return len;
    }

    nm_assert(cb_data->concheck.response_good_cnt < strlen(response));

    response_len = strlen(response);

    check_len = NM_MIN(len, response_len - cb_data->concheck.response_good_cnt);

    if (strncmp(&response[cb_data->concheck.response_good_cnt], buffer, check_len) != 0) {
        cb_data_queue_completed(cb_data, NM_CONNECTIVITY_PORTAL, "unexpected response", NULL);
        return 0;
    }

    cb_data->concheck.response_good_cnt += len;

    if (cb_data->concheck.response_good_cnt >= response_len) {
        /* We already have enough data, and it matched. */
        cb_data_queue_completed(cb_data, NM_CONNECTIVITY_FULL, "expected response", NULL);
        return 0;
    }

    return len;
}

static gboolean
_timeout_cb(gpointer user_data)
{
    NMConnectivityCheckHandle *cb_data = user_data;

    nm_assert(NM_IS_CONNECTIVITY(cb_data->self));
    nm_assert(c_list_contains(&NM_CONNECTIVITY_GET_PRIVATE(cb_data->self)->handles_lst_head,
                              &cb_data->handles_lst));

    cb_data_complete(cb_data, NM_CONNECTIVITY_LIMITED, "timeout");
    return G_SOURCE_REMOVE;
}
#endif

static gboolean
_idle_cb(gpointer user_data)
{
    NMConnectivityCheckHandle *cb_data = user_data;

    nm_assert(NM_IS_CONNECTIVITY(cb_data->self));
    nm_assert(c_list_contains(&NM_CONNECTIVITY_GET_PRIVATE(cb_data->self)->handles_lst_head,
                              &cb_data->handles_lst));
    nm_assert(cb_data->completed_reason);

    nm_clear_g_source_inst(&cb_data->timeout_source);
    cb_data_complete(cb_data, cb_data->completed_state, cb_data->completed_reason);
    return G_SOURCE_CONTINUE;
}

#if WITH_CONCHECK
static void
do_curl_request(NMConnectivityCheckHandle *cb_data)
{
    CURLM *mhandle;
    CURL  *ehandle;
    long   resolve;

    mhandle = curl_multi_init();
    if (!mhandle) {
        cb_data_complete(cb_data, NM_CONNECTIVITY_ERROR, "curl error");
        return;
    }

    ehandle = curl_easy_init();
    if (!ehandle) {
        curl_multi_cleanup(mhandle);
        cb_data_complete(cb_data, NM_CONNECTIVITY_ERROR, "curl error");
        return;
    }

    cb_data->concheck.curl_mhandle    = mhandle;
    cb_data->concheck.curl_ehandle    = ehandle;
    cb_data->concheck.request_headers = curl_slist_append(NULL, "Connection: close");
    cb_data->timeout_source           = nm_g_timeout_add_seconds_source(20, _timeout_cb, cb_data);

    curl_multi_setopt(mhandle, CURLMOPT_SOCKETFUNCTION, multi_socket_cb);
    curl_multi_setopt(mhandle, CURLMOPT_SOCKETDATA, cb_data);
    curl_multi_setopt(mhandle, CURLMOPT_TIMERFUNCTION, multi_timer_cb);
    curl_multi_setopt(mhandle, CURLMOPT_TIMERDATA, cb_data);

    switch (cb_data->addr_family) {
    case AF_INET:
        resolve = CURL_IPRESOLVE_V4;
        break;
    case AF_INET6:
        resolve = CURL_IPRESOLVE_V6;
        break;
    case AF_UNSPEC:
        resolve = CURL_IPRESOLVE_WHATEVER;
        break;
    default:
        resolve = CURL_IPRESOLVE_WHATEVER;
        g_warn_if_reached();
    }

    curl_easy_setopt(ehandle, CURLOPT_URL, cb_data->concheck.con_config->uri);
    curl_easy_setopt(ehandle, CURLOPT_WRITEFUNCTION, easy_write_cb);
    curl_easy_setopt(ehandle, CURLOPT_WRITEDATA, cb_data);
    curl_easy_setopt(ehandle, CURLOPT_HEADERFUNCTION, easy_header_cb);
    curl_easy_setopt(ehandle, CURLOPT_HEADERDATA, cb_data);
    curl_easy_setopt(ehandle, CURLOPT_PRIVATE, cb_data);
    curl_easy_setopt(ehandle, CURLOPT_HTTPHEADER, cb_data->concheck.request_headers);
    curl_easy_setopt(ehandle, CURLOPT_INTERFACE, cb_data->ifspec);
    curl_easy_setopt(ehandle, CURLOPT_RESOLVE, cb_data->concheck.hosts);
    curl_easy_setopt(ehandle, CURLOPT_IPRESOLVE, resolve);
    curl_easy_setopt(ehandle, CURLOPT_PROTOCOLS, CURLPROTO_HTTP | CURLPROTO_HTTPS);

    curl_multi_add_handle(mhandle, ehandle);
}

static void
resolve_cb(GObject *object, GAsyncResult *res, gpointer user_data)
{
    NMConnectivityCheckHandle *cb_data;
    gs_unref_variant GVariant *result    = NULL;
    gs_unref_variant GVariant *addresses = NULL;
    gsize                      no_addresses;
    int                        ifindex;
    int                        addr_family;
    gsize                      len = 0;
    gsize                      i;
    gs_free_error GError      *error        = NULL;
    nm_auto_str_buf NMStrBuf   strbuf_hosts = NM_STR_BUF_INIT(0, FALSE);

    result = g_dbus_connection_call_finish(G_DBUS_CONNECTION(object), res, &error);
    if (g_error_matches(error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
        return;

    cb_data = user_data;

    g_clear_object(&cb_data->concheck.resolve_cancellable);

    if (!result) {
        /* Never mind. Just let do curl do its own resolving. */
        _LOG2D("can't resolve a name via systemd-resolved: %s", error->message);
        do_curl_request(cb_data);
        return;
    }

    addresses    = g_variant_get_child_value(result, 0);
    no_addresses = g_variant_n_children(addresses);

    for (i = 0; i < no_addresses; i++) {
        gs_unref_variant GVariant *address = NULL;
        char                       str_addr[NM_UTILS_INET_ADDRSTRLEN];
        const guchar              *address_buf;

        g_variant_get_child(addresses, i, "(ii@ay)", &ifindex, &addr_family, &address);

        if (!NM_IN_SET(addr_family, AF_INET, AF_INET6))
            continue;

        if (cb_data->addr_family != AF_UNSPEC && cb_data->addr_family != addr_family)
            continue;

        address_buf = g_variant_get_fixed_array(address, &len, 1);
        if (len != nm_utils_addr_family_to_size(addr_family))
            continue;

        if (strbuf_hosts.len == 0) {
            nm_str_buf_append_printf(&strbuf_hosts,
                                     "%s:%s:",
                                     cb_data->concheck.con_config->host,
                                     cb_data->concheck.con_config->port ?: "80");
        } else
            nm_str_buf_append_c(&strbuf_hosts, ',');

        nm_str_buf_append(&strbuf_hosts, nm_utils_inet_ntop(addr_family, address_buf, str_addr));
    }
    if (strbuf_hosts.len > 0) {
        const char *s = nm_str_buf_get_str(&strbuf_hosts);

        cb_data->concheck.hosts = curl_slist_append(NULL, s);
        _LOG2T("set curl resolve list to '%s'", s);
    }

    do_curl_request(cb_data);
}
#endif

#define SD_RESOLVED_DNS ((guint64) (1LL << 0))

static NMConnectivityState
check_platform_config(NMConnectivity *self,
                      NMPlatform     *platform,
                      int             ifindex,
                      int             addr_family,
                      const char    **reason)
{
    const NMDedupMultiHeadEntry *addresses;
    const NMDedupMultiHeadEntry *routes;

    if (!nm_platform_link_is_connected(platform, ifindex)) {
        NM_SET_OUT(reason, "no carrier");
        return NM_CONNECTIVITY_NONE;
    }

    addresses = nm_platform_lookup_object(platform,
                                          addr_family == AF_INET ? NMP_OBJECT_TYPE_IP4_ADDRESS
                                                                 : NMP_OBJECT_TYPE_IP6_ADDRESS,
                                          ifindex);
    if (!addresses || addresses->len == 0) {
        NM_SET_OUT(reason, "no IP address configured");
        return NM_CONNECTIVITY_NONE;
    }

    routes = nm_platform_lookup_object(platform,
                                       addr_family == AF_INET ? NMP_OBJECT_TYPE_IP4_ROUTE
                                                              : NMP_OBJECT_TYPE_IP6_ROUTE,
                                       ifindex);
    if (!routes || routes->len == 0) {
        NM_SET_OUT(reason, "no IP route configured");
        return NM_CONNECTIVITY_NONE;
    }

    switch (addr_family) {
    case AF_INET:
    {
        const NMPlatformIP4Route *route;
        gboolean                  found_global = FALSE;
        NMDedupMultiIter          iter;
        const NMPObject          *plobj;

        /* For IPv4 also require a route with global scope. */
        nmp_cache_iter_for_each (&iter, routes, &plobj) {
            route = NMP_OBJECT_CAST_IP4_ROUTE(plobj);
            if (nm_platform_route_scope_inv(route->scope_inv) == RT_SCOPE_UNIVERSE) {
                found_global = TRUE;
                break;
            }
        }

        if (!found_global) {
            NM_SET_OUT(reason, "no global route configured");
            return NM_CONNECTIVITY_LIMITED;
        }
        break;
    }
    case AF_INET6:
        /* Route scopes aren't meaningful for IPv6 so any route is fine. */
        break;
    default:
        g_return_val_if_reached(FALSE);
    }

    NM_SET_OUT(reason, NULL);
    return NM_CONNECTIVITY_UNKNOWN;
}

NMConnectivityCheckHandle *
nm_connectivity_check_start(NMConnectivity             *self,
                            int                         addr_family,
                            NMPlatform                 *platform,
                            int                         ifindex,
                            const char                 *iface,
                            NMConnectivityCheckCallback callback,
                            gpointer                    user_data)
{
    NMConnectivityPrivate     *priv;
    NMConnectivityCheckHandle *cb_data;
    static guint64             request_counter = 0;

    g_return_val_if_fail(NM_IS_CONNECTIVITY(self), NULL);
    g_return_val_if_fail(callback, NULL);
    nm_assert(!platform || NM_IS_PLATFORM(platform));

    priv = NM_CONNECTIVITY_GET_PRIVATE(self);

    cb_data                  = g_slice_new0(NMConnectivityCheckHandle);
    cb_data->self            = self;
    cb_data->request_counter = ++request_counter;
    c_list_link_tail(&priv->handles_lst_head, &cb_data->handles_lst);
    cb_data->callback        = callback;
    cb_data->user_data       = user_data;
    cb_data->completed_state = NM_CONNECTIVITY_UNKNOWN;
    cb_data->addr_family     = addr_family;
    if (iface)
        cb_data->ifspec = g_strdup_printf("if!%s", iface);

#if WITH_CONCHECK

    cb_data->concheck.con_config = _con_config_ref(priv->con_config);

    if (iface && ifindex > 0 && priv->enabled && priv->uri_valid) {
        gboolean            has_systemd_resolved;
        NMConnectivityState state;
        const char         *reason;

        cb_data->concheck.ch_ifindex = ifindex;

        if (platform) {
            state = check_platform_config(self, platform, ifindex, addr_family, &reason);
            nm_assert((state == NM_CONNECTIVITY_UNKNOWN) == !reason);
            if (state != NM_CONNECTIVITY_UNKNOWN) {
                _LOG2D("skip connectivity check due to %s", reason);
                cb_data->completed_state  = state;
                cb_data->completed_reason = reason;
                cb_data->timeout_source   = nm_g_idle_add_source(_idle_cb, cb_data);
                return cb_data;
            }
        }

        /* note that we pick up support for systemd-resolved right away when we need it.
         * We don't need to remember the setting, because we can (cheaply) check anew
         * on each request.
         *
         * Yes, this makes NMConnectivity singleton dependent on NMDnsManager singleton.
         * Well, not really: it makes connectivity-check-start dependent on NMDnsManager
         * which merely means, not to start a connectivity check, late during shutdown.
         *
         * NMDnsSystemdResolved tries to D-Bus activate systemd-resolved only once,
         * to not spam syslog with failures messages from dbus-daemon.
         * Note that unless NMDnsSystemdResolved tried and failed to start systemd-resolved,
         * it guesses that systemd-resolved is activatable and returns %TRUE here. That
         * means, while NMDnsSystemdResolved would not try to D-Bus activate systemd-resolved
         * more than once, NMConnectivity might -- until NMDnsSystemdResolved tried itself
         * and noticed that systemd-resolved is not available.
         * This is relatively cumbersome to avoid, because we would have to go through
         * NMDnsSystemdResolved trying to asynchronously start the service, to ensure there
         * is only one attempt to start the service. */
        has_systemd_resolved = !!nm_dns_manager_get_systemd_resolved(nm_dns_manager_get());

        if (has_systemd_resolved) {
            GDBusConnection *dbus_connection;

            dbus_connection = NM_MAIN_DBUS_CONNECTION_GET;
            if (!dbus_connection) {
                /* we have no D-Bus connection? That might happen in configure and quit mode.
                 *
                 * Anyway, something is very odd, just fail connectivity check. */
                _LOG2D("start fake request (fail due to no D-Bus connection)");
                cb_data->completed_state  = NM_CONNECTIVITY_ERROR;
                cb_data->completed_reason = "no D-Bus connection";
                cb_data->timeout_source   = nm_g_idle_add_source(_idle_cb, cb_data);
                return cb_data;
            }

            cb_data->concheck.resolve_cancellable = g_cancellable_new();

            g_dbus_connection_call(dbus_connection,
                                   "org.freedesktop.resolve1",
                                   "/org/freedesktop/resolve1",
                                   "org.freedesktop.resolve1.Manager",
                                   "ResolveHostname",
                                   g_variant_new("(isit)",
                                                 (gint32) cb_data->concheck.ch_ifindex,
                                                 cb_data->concheck.con_config->host,
                                                 (gint32) cb_data->addr_family,
                                                 SD_RESOLVED_DNS),
                                   G_VARIANT_TYPE("(a(iiay)st)"),
                                   G_DBUS_CALL_FLAGS_NONE,
                                   -1,
                                   cb_data->concheck.resolve_cancellable,
                                   resolve_cb,
                                   cb_data);
            _LOG2D("start request to '%s' (try resolving '%s' using systemd-resolved)",
                   cb_data->concheck.con_config->uri,
                   cb_data->concheck.con_config->host);
        } else {
            _LOG2D("start request to '%s' (systemd-resolved not available)",
                   cb_data->concheck.con_config->uri);
            do_curl_request(cb_data);
        }

        return cb_data;
    }
#endif

    if (!cb_data->ifspec) {
        cb_data->completed_state  = NM_CONNECTIVITY_ERROR;
        cb_data->completed_reason = "missing interface";
    } else {
        cb_data->completed_state  = NM_CONNECTIVITY_FAKE;
        cb_data->completed_reason = "fake result";
    }
    _LOG2D("start fake request (%s)", cb_data->completed_reason);
    cb_data->timeout_source = nm_g_idle_add_source(_idle_cb, cb_data);

    return cb_data;
}

void
nm_connectivity_check_cancel(NMConnectivityCheckHandle *cb_data)
{
    g_return_if_fail(cb_data);
    g_return_if_fail(NM_IS_CONNECTIVITY(cb_data->self));

    nm_assert(
        c_list_contains(&NM_CONNECTIVITY_GET_PRIVATE(cb_data->self)->handles_lst_head,
                        &cb_data->handles_lst)
        || c_list_contains(&NM_CONNECTIVITY_GET_PRIVATE(cb_data->self)->completed_handles_lst_head,
                           &cb_data->handles_lst));

    cb_data_complete(cb_data, NM_CONNECTIVITY_CANCELLED, "cancelled");
}

/*****************************************************************************/

gboolean
nm_connectivity_check_enabled(NMConnectivity *self)
{
    g_return_val_if_fail(NM_IS_CONNECTIVITY(self), FALSE);

    return NM_CONNECTIVITY_GET_PRIVATE(self)->enabled;
}

/*****************************************************************************/

guint
nm_connectivity_get_interval(NMConnectivity *self)
{
    return nm_connectivity_check_enabled(self) ? NM_CONNECTIVITY_GET_PRIVATE(self)->interval : 0;
}

static gboolean
host_and_port_from_uri(const char *uri, char **host, char **port)
{
    const char *p          = uri;
    const char *host_begin = NULL;
    size_t      host_len   = 0;
    const char *port_begin = NULL;
    size_t      port_len   = 0;

    /* scheme */
    while (*p != ':' && *p != '/') {
        if (!*p++)
            return FALSE;
    }

    /* :// */
    if (*p++ != ':')
        return FALSE;
    if (*p++ != '/')
        return FALSE;
    if (*p++ != '/')
        return FALSE;
    /* host */
    if (*p == '[')
        return FALSE;
    host_begin = p;
    while (*p && *p != ':' && *p != '/') {
        host_len++;
        p++;
    }
    if (host_len == 0)
        return FALSE;
    *host = g_strndup(host_begin, host_len);

    /* port */
    if (*p++ == ':') {
        port_begin = p;
        while (*p && *p != '/') {
            port_len++;
            p++;
        }
        if (port_len)
            *port = g_strndup(port_begin, port_len);
    }

    return TRUE;
}

static void
update_config(NMConnectivity *self, NMConfigData *config_data)
{
    NMConnectivityPrivate *priv = NM_CONNECTIVITY_GET_PRIVATE(self);
    guint                  interval;
    gboolean               enabled;
    gboolean               changed      = FALSE;
    const char            *cur_uri      = priv->con_config ? priv->con_config->uri : NULL;
    const char            *cur_response = priv->con_config ? priv->con_config->response : NULL;
    const char            *new_response;
    const char            *new_uri;
    gboolean               new_uri_valid = priv->uri_valid;
    gboolean               new_host_port = FALSE;
    gs_free char          *new_host      = NULL;
    gs_free char          *new_port      = NULL;

    new_uri = nm_config_data_get_connectivity_uri(config_data);
    if (!nm_streq0(new_uri, cur_uri)) {
        new_uri_valid = (new_uri && *new_uri);
        if (new_uri_valid) {
            gs_free char *scheme   = g_uri_parse_scheme(new_uri);
            gboolean      is_https = FALSE;

            if (!scheme) {
                _LOGE("invalid URI '%s' for connectivity check.", new_uri);
                new_uri_valid = FALSE;
            } else if (g_ascii_strcasecmp(scheme, "https") == 0) {
                _LOGW("use of HTTPS for connectivity checking is not reliable and is discouraged "
                      "(URI: %s)",
                      new_uri);
                is_https = TRUE;
            } else if (g_ascii_strcasecmp(scheme, "http") != 0) {
                _LOGE("scheme of '%s' uri doesn't use a scheme that is allowed for connectivity "
                      "check.",
                      new_uri);
                new_uri_valid = FALSE;
            }
            if (new_uri_valid) {
                new_host_port = TRUE;
                if (!host_and_port_from_uri(new_uri, &new_host, &new_port)) {
                    _LOGE("cannot parse host and port from '%s'", new_uri);
                    new_uri_valid = FALSE;
                } else if (!new_port && is_https)
                    new_port = g_strdup("443");
            }
        }

        if (new_uri_valid || priv->uri_valid != new_uri_valid)
            changed = TRUE;
    }

    new_response = nm_config_data_get_connectivity_response(config_data);
    if (!nm_streq0(new_response, cur_response))
        changed = TRUE;

    if (!priv->con_config || !nm_streq0(new_uri, priv->con_config->uri)
        || !nm_streq0(new_response, priv->con_config->response)) {
        if (!new_host_port) {
            new_host = priv->con_config ? g_strdup(priv->con_config->host) : NULL;
            new_port = priv->con_config ? g_strdup(priv->con_config->port) : NULL;
        }
        _con_config_unref(priv->con_config);
        priv->con_config  = g_slice_new(ConConfig);
        *priv->con_config = (ConConfig){
            .ref_count = 1,
            .uri       = g_strdup(new_uri),
            .response  = g_strdup(new_response),
            .host      = g_steal_pointer(&new_host),
            .port      = g_steal_pointer(&new_port),
        };
    }
    priv->uri_valid = new_uri_valid;

    interval = nm_config_data_get_connectivity_interval(config_data);
    interval = MIN(interval, (7 * 24 * 3600));
    if (priv->interval != interval) {
        priv->interval = interval;
        changed        = TRUE;
    }

    enabled = FALSE;
#if WITH_CONCHECK
    if (priv->uri_valid && priv->interval)
        enabled = nm_config_data_get_connectivity_enabled(config_data);
#endif

    if (priv->enabled != enabled) {
        priv->enabled = enabled;
        changed       = TRUE;
    }

    if (changed)
        g_signal_emit(self, signals[CONFIG_CHANGED], 0);
}

static void
config_changed_cb(NMConfig           *config,
                  NMConfigData       *config_data,
                  NMConfigChangeFlags changes,
                  NMConfigData       *old_data,
                  NMConnectivity     *self)
{
    update_config(self, config_data);
}

/*****************************************************************************/

static void
nm_connectivity_init(NMConnectivity *self)
{
    NMConnectivityPrivate *priv = NM_CONNECTIVITY_GET_PRIVATE(self);
#if WITH_CONCHECK
    CURLcode ret;
#endif

    c_list_init(&priv->handles_lst_head);
    c_list_init(&priv->completed_handles_lst_head);

    priv->config = g_object_ref(nm_config_get());
    g_signal_connect(G_OBJECT(priv->config),
                     NM_CONFIG_SIGNAL_CONFIG_CHANGED,
                     G_CALLBACK(config_changed_cb),
                     self);

#if WITH_CONCHECK
    ret = curl_global_init(CURL_GLOBAL_ALL);
    if (ret != CURLE_OK) {
        _LOGE("unable to init cURL, connectivity check will not work: (%d) %s",
              ret,
              curl_easy_strerror(ret));
    }
#endif

    update_config(self, nm_config_get_data(priv->config));
}

static void
dispose(GObject *object)
{
    NMConnectivity            *self = NM_CONNECTIVITY(object);
    NMConnectivityPrivate     *priv = NM_CONNECTIVITY_GET_PRIVATE(self);
    NMConnectivityCheckHandle *cb_data;

    nm_assert(c_list_is_empty(&priv->completed_handles_lst_head));

    while (
        (cb_data =
             c_list_first_entry(&priv->handles_lst_head, NMConnectivityCheckHandle, handles_lst)))
        cb_data_complete(cb_data, NM_CONNECTIVITY_DISPOSING, "shutting down");

    nm_clear_pointer(&priv->con_config, _con_config_unref);

#if WITH_CONCHECK
    curl_global_cleanup();
#endif

    if (priv->config) {
        g_signal_handlers_disconnect_by_func(priv->config, config_changed_cb, self);
        g_clear_object(&priv->config);
    }

    G_OBJECT_CLASS(nm_connectivity_parent_class)->dispose(object);
}

static void
nm_connectivity_class_init(NMConnectivityClass *klass)
{
    GObjectClass *object_class = G_OBJECT_CLASS(klass);

    signals[CONFIG_CHANGED] = g_signal_new(NM_CONNECTIVITY_CONFIG_CHANGED,
                                           G_OBJECT_CLASS_TYPE(object_class),
                                           G_SIGNAL_RUN_FIRST,
                                           0,
                                           NULL,
                                           NULL,
                                           NULL,
                                           G_TYPE_NONE,
                                           0);

    object_class->dispose = dispose;
}
