/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include "libnm-client-aux-extern/nm-default-client.h"

#include "nmcs-provider-ec2.h"

#include "nm-cloud-setup-utils.h"

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

#define HTTP_TIMEOUT_MS 3000

#define NM_EC2_HOST              "169.254.169.254"
#define NM_EC2_BASE              "http://" NM_EC2_HOST
#define NM_EC2_API_VERSION       "2018-09-24"
#define NM_EC2_METADATA_URL_BASE /* $NM_EC2_BASE/$NM_EC2_API_VERSION */ \
    "/meta-data/network/interfaces/macs/"

/* Token TTL of 180 seconds is chosen abitrarily, in hope that it is
 * surely more than enough to read all relevant metadata. */
#define NM_EC2_TOKEN_TTL_HEADER "X-aws-ec2-metadata-token-ttl-seconds: 180"
#define NM_EC2_TOKEN_HEADER     "X-aws-ec2-metadata-token: "

static const char *
_ec2_base(void)
{
    static const char *base_cached = NULL;
    const char        *base;

again:
    base = g_atomic_pointer_get(&base_cached);
    if (G_UNLIKELY(!base)) {
        /* The base URI can be set via environment variable.
         * This is mainly for testing, it's not usually supposed to be configured.
         * Consider this private API! */
        base = g_getenv(NMCS_ENV_VARIABLE("NM_CLOUD_SETUP_EC2_HOST"));
        base = nmcs_utils_uri_complete_interned(base) ?: ("" NM_EC2_BASE);

        if (!g_atomic_pointer_compare_and_exchange(&base_cached, NULL, base))
            goto again;
    }

    return base;
}

#define _ec2_uri_concat(...) nmcs_utils_uri_build_concat(_ec2_base(), __VA_ARGS__)
#define _ec2_uri_interfaces(...) \
    _ec2_uri_concat(NM_EC2_API_VERSION, NM_EC2_METADATA_URL_BASE, ##__VA_ARGS__)

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

enum {
    NM_EC2_HTTP_HEADER_TOKEN,
    NM_EC2_HTTP_HEADER_SENTINEL,
    _NM_EC2_HTTP_HEADER_NUM,
};

struct _NMCSProviderEC2 {
    NMCSProvider parent;
    char        *token;
};

struct _NMCSProviderEC2Class {
    NMCSProviderClass parent;
};

G_DEFINE_TYPE(NMCSProviderEC2, nmcs_provider_ec2, NMCS_TYPE_PROVIDER);

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

static void
_detect_get_token_done_cb(GObject *source, GAsyncResult *result, gpointer user_data)
{
    gs_unref_object GTask *task      = user_data;
    NMCSProviderEC2       *self      = NMCS_PROVIDER_EC2(g_task_get_source_object(task));
    gs_unref_bytes GBytes *response  = NULL;
    gs_free_error GError  *get_error = NULL;
    gs_free_error GError  *error     = NULL;

    nm_clear_g_free(&self->token);

    nm_http_client_poll_req_finish(NM_HTTP_CLIENT(source), result, NULL, &response, &get_error);

    if (nm_utils_error_is_cancelled(get_error)) {
        g_task_return_error(task, g_steal_pointer(&get_error));
        return;
    }

    if (get_error) {
        nm_utils_error_set(&error,
                           NM_UTILS_ERROR_UNKNOWN,
                           "failure to get EC2 metadata: %s",
                           get_error->message);
        g_task_return_error(task, g_steal_pointer(&error));
        return;
    }

    /* We use the token as-is. Special characters can cause confusion (e.g.
     * response splitting), but we're not crossing a security boundary.
     * None of the examples in AWS documentation does any sort of
     * sanitization either.  */
    self->token = g_strconcat(NM_EC2_TOKEN_HEADER, g_bytes_get_data(response, NULL), NULL);

    g_task_return_boolean(task, TRUE);
}

static void
detect(NMCSProvider *provider, GTask *task)
{
    NMHttpClient *http_client;
    gs_free char *uri = NULL;

    http_client = nmcs_provider_get_http_client(provider);

    nm_http_client_poll_req(http_client,
                            (uri = _ec2_uri_concat("latest/api/token")),
                            HTTP_TIMEOUT_MS,
                            256 * 1024,
                            7000,
                            1000,
                            NM_MAKE_STRV(NM_EC2_TOKEN_TTL_HEADER),
                            "PUT",
                            g_task_get_cancellable(task),
                            NULL,
                            NULL,
                            _detect_get_token_done_cb,
                            task);
}

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

static void
_get_config_fetch_done_cb(NMHttpClient                   *http_client,
                          GAsyncResult                   *result,
                          NMCSProviderGetConfigIfaceData *config_iface_data,
                          gboolean                        is_local_ipv4)
{
    gs_unref_bytes GBytes *response = NULL;
    gs_free_error GError  *error    = NULL;
    in_addr_t              tmp_addr;
    int                    tmp_prefix;

    nm_http_client_poll_req_finish(http_client, result, NULL, &response, &error);

    if (nm_utils_error_is_cancelled(error))
        return;

    if (error)
        goto out;

    if (is_local_ipv4) {
        gs_free const char **s_addrs = NULL;
        gsize                i, len;

        s_addrs = nm_strsplit_set_full(g_bytes_get_data(response, NULL),
                                       "\n",
                                       NM_STRSPLIT_SET_FLAGS_STRSTRIP);
        len     = NM_PTRARRAY_LEN(s_addrs);

        nm_assert(!config_iface_data->has_ipv4s);
        nm_assert(!config_iface_data->ipv4s_arr);
        config_iface_data->has_ipv4s = TRUE;
        config_iface_data->ipv4s_len = 0;
        if (len > 0) {
            config_iface_data->ipv4s_arr = g_new(in_addr_t, len);

            for (i = 0; i < len; i++) {
                if (nm_utils_parse_inaddr_bin(AF_INET, s_addrs[i], NULL, &tmp_addr))
                    config_iface_data->ipv4s_arr[config_iface_data->ipv4s_len++] = tmp_addr;
            }
        }
    } else {
        if (nm_utils_parse_inaddr_prefix_bin(AF_INET,
                                             g_bytes_get_data(response, NULL),
                                             NULL,
                                             &tmp_addr,
                                             &tmp_prefix)) {
            nm_assert(!config_iface_data->has_cidr);
            config_iface_data->has_cidr    = TRUE;
            config_iface_data->cidr_prefix = tmp_prefix;
            config_iface_data->cidr_addr   = tmp_addr;
        }
    }

out:
    config_iface_data->get_config_data->n_pending--;
    _nmcs_provider_get_config_task_maybe_return(config_iface_data->get_config_data,
                                                g_steal_pointer(&error));
}

static void
_get_config_fetch_done_cb_subnet_ipv4_cidr_block(GObject      *source,
                                                 GAsyncResult *result,
                                                 gpointer      user_data)
{
    _get_config_fetch_done_cb(NM_HTTP_CLIENT(source), result, user_data, FALSE);
}

static void
_get_config_fetch_done_cb_local_ipv4s(GObject *source, GAsyncResult *result, gpointer user_data)
{
    _get_config_fetch_done_cb(NM_HTTP_CLIENT(source), result, user_data, TRUE);
}

typedef struct {
    gssize iface_idx;
    char   path[0];
} GetConfigMetadataMac;

static void
_get_config_metadata_ready_cb(GObject *source, GAsyncResult *result, gpointer user_data)
{
    NMCSProviderGetConfigTaskData *get_config_data;
    NMCSProviderEC2               *self;
    gs_unref_hashtable GHashTable *response_parsed = NULL;
    gs_free_error GError          *error           = NULL;
    GetConfigMetadataMac          *v_mac_data;
    const char                    *v_hwaddr;
    GHashTableIter                 h_iter;
    NMHttpClient                  *http_client;

    nm_http_client_poll_req_finish(NM_HTTP_CLIENT(source), result, NULL, NULL, &error);

    if (nm_utils_error_is_cancelled(error))
        return;

    get_config_data = user_data;
    self            = NMCS_PROVIDER_EC2(get_config_data->self);

    response_parsed                     = g_steal_pointer(&get_config_data->extra_data);
    get_config_data->extra_data_destroy = NULL;

    /* We ignore errors. Only if we got no response at all, it's a problem.
     * Otherwise, we proceed with whatever we could fetch. */
    if (!response_parsed) {
        _nmcs_provider_get_config_task_maybe_return(
            get_config_data,
            nm_utils_error_new(NM_UTILS_ERROR_UNKNOWN, "meta data for interfaces not found"));
        return;
    }

    http_client = nmcs_provider_get_http_client(g_task_get_source_object(get_config_data->task));

    g_hash_table_iter_init(&h_iter, response_parsed);
    while (g_hash_table_iter_next(&h_iter, (gpointer *) &v_hwaddr, (gpointer *) &v_mac_data)) {
        NMCSProviderGetConfigIfaceData *config_iface_data;
        gs_free char                   *uri1 = NULL;
        gs_free char                   *uri2 = NULL;

        config_iface_data = g_hash_table_lookup(get_config_data->result_dict, v_hwaddr);

        if (!config_iface_data) {
            if (!get_config_data->any) {
                _LOGD("get-config: skip fetching meta data for %s (%s)",
                      v_hwaddr,
                      v_mac_data->path);
                continue;
            }
            config_iface_data =
                nmcs_provider_get_config_iface_data_create(get_config_data, FALSE, v_hwaddr);
        }

        nm_assert(config_iface_data->iface_idx == -1);

        config_iface_data->iface_idx = v_mac_data->iface_idx;

        _LOGD("get-config: start fetching meta data for #%" G_GSSIZE_FORMAT ", %s (%s)",
              config_iface_data->iface_idx,
              config_iface_data->hwaddr,
              v_mac_data->path);

        get_config_data->n_pending++;
        nm_http_client_poll_req(
            http_client,
            (uri1 = _ec2_uri_interfaces(v_mac_data->path,
                                        NM_STR_HAS_SUFFIX(v_mac_data->path, "/") ? "" : "/",
                                        "subnet-ipv4-cidr-block")),
            HTTP_TIMEOUT_MS,
            512 * 1024,
            10000,
            1000,
            NM_MAKE_STRV(self->token),
            NULL,
            get_config_data->intern_cancellable,
            NULL,
            NULL,
            _get_config_fetch_done_cb_subnet_ipv4_cidr_block,
            config_iface_data);

        get_config_data->n_pending++;
        nm_http_client_poll_req(
            http_client,
            (uri2 = _ec2_uri_interfaces(v_mac_data->path,
                                        NM_STR_HAS_SUFFIX(v_mac_data->path, "/") ? "" : "/",
                                        "local-ipv4s")),
            HTTP_TIMEOUT_MS,
            512 * 1024,
            10000,
            1000,
            NM_MAKE_STRV(self->token),
            NULL,
            get_config_data->intern_cancellable,
            NULL,
            NULL,
            _get_config_fetch_done_cb_local_ipv4s,
            config_iface_data);
    }

    _nmcs_provider_get_config_task_maybe_return(get_config_data, NULL);
}

static gboolean
_get_config_metadata_ready_check(long     response_code,
                                 GBytes  *response,
                                 gpointer check_user_data,
                                 GError **error)
{
    NMCSProviderGetConfigTaskData *get_config_data = check_user_data;
    gs_unref_hashtable GHashTable *response_parsed = NULL;
    const guint8                  *r_data;
    const char                    *cur_line;
    gsize                          r_len;
    gsize                          cur_line_len;
    GHashTableIter                 h_iter;
    gboolean                       has_all;
    const char                    *c_hwaddr;
    gssize                         iface_idx_counter = 0;

    if (response_code != 200 || !response) {
        /* we wait longer. */
        return FALSE;
    }

    r_data = g_bytes_get_data(response, &r_len);
    /* NMHttpClient guarantees that there is a trailing NUL after the data. */
    nm_assert(r_data[r_len] == 0);

    while (nm_utils_parse_next_line((const char **) &r_data, &r_len, &cur_line, &cur_line_len)) {
        GetConfigMetadataMac *mac_data;
        char                 *hwaddr;

        if (cur_line_len == 0)
            continue;

        /* Truncate the string. It's safe to do, because we own @response an it has an
         * extra NUL character after the buffer. */
        ((char *) cur_line)[cur_line_len] = '\0';

        hwaddr = nmcs_utils_hwaddr_normalize(
            cur_line,
            cur_line[cur_line_len - 1u] == '/' ? (gssize) (cur_line_len - 1u) : -1);
        if (!hwaddr)
            continue;

        if (!response_parsed)
            response_parsed = g_hash_table_new_full(nm_str_hash, g_str_equal, g_free, g_free);

        mac_data            = g_malloc(sizeof(GetConfigMetadataMac) + 1u + cur_line_len);
        mac_data->iface_idx = iface_idx_counter++;
        memcpy(mac_data->path, cur_line, cur_line_len + 1u);

        /* here we will ignore duplicate responses. */
        g_hash_table_insert(response_parsed, hwaddr, mac_data);
    }

    has_all = TRUE;
    g_hash_table_iter_init(&h_iter, get_config_data->result_dict);
    while (g_hash_table_iter_next(&h_iter, (gpointer *) &c_hwaddr, NULL)) {
        if (!response_parsed || !g_hash_table_contains(response_parsed, c_hwaddr)) {
            has_all = FALSE;
            break;
        }
    }

    nm_clear_pointer(&get_config_data->extra_data, g_hash_table_unref);
    if (response_parsed) {
        get_config_data->extra_data         = g_steal_pointer(&response_parsed);
        get_config_data->extra_data_destroy = (GDestroyNotify) g_hash_table_unref;
    }
    return has_all;
}

static void
get_config(NMCSProvider *provider, NMCSProviderGetConfigTaskData *get_config_data)
{
    NMCSProviderEC2 *self = NMCS_PROVIDER_EC2(provider);
    gs_free char    *uri  = NULL;

    /* This can be called only if detect() succeeded, which implies
     * there must be a token.
     */
    nm_assert(self->token);

    /* First we fetch the "macs/". If the caller requested some particular
     * MAC addresses, then we poll until we see them. They might not yet be
     * around from the start...
     */
    nm_http_client_poll_req(nmcs_provider_get_http_client(provider),
                            (uri = _ec2_uri_interfaces()),
                            HTTP_TIMEOUT_MS,
                            256 * 1024,
                            15000,
                            1000,
                            NM_MAKE_STRV(self->token),
                            NULL,
                            get_config_data->intern_cancellable,
                            _get_config_metadata_ready_check,
                            get_config_data,
                            _get_config_metadata_ready_cb,
                            get_config_data);
}

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

static void
nmcs_provider_ec2_init(NMCSProviderEC2 *self)
{}

static void
dispose(GObject *object)
{
    NMCSProviderEC2 *self = NMCS_PROVIDER_EC2(object);

    nm_clear_g_free(&self->token);

    G_OBJECT_CLASS(nmcs_provider_ec2_parent_class)->dispose(object);
}

static void
nmcs_provider_ec2_class_init(NMCSProviderEC2Class *klass)
{
    GObjectClass      *object_class   = G_OBJECT_CLASS(klass);
    NMCSProviderClass *provider_class = NMCS_PROVIDER_CLASS(klass);

    object_class->dispose = dispose;

    provider_class->_name                 = "ec2";
    provider_class->_env_provider_enabled = NMCS_ENV_VARIABLE("NM_CLOUD_SETUP_EC2");
    provider_class->detect                = detect;
    provider_class->get_config            = get_config;
}
