/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Copyright (C) 2015 - 2018 Red Hat, Inc.
 */

#include "nm-default.h"

#include "nm-acd-manager.h"

#include <netinet/in.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <linux/if_ether.h>

#include "platform/nm-platform.h"
#include "nm-utils.h"
#include "NetworkManagerUtils.h"
#include "n-acd/src/n-acd.h"

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

typedef enum {
    STATE_INIT,
    STATE_PROBING,
    STATE_PROBE_DONE,
    STATE_ANNOUNCING,
} State;

typedef struct {
    in_addr_t  address;
    gboolean   duplicate;
    NAcdProbe *probe;
} AddressInfo;

struct _NMAcdManager {
    int         ifindex;
    guint8      hwaddr[ETH_ALEN];
    State       state;
    GHashTable *addresses;
    guint       completed;
    NAcd *      acd;
    GSource *   event_source;

    NMAcdCallbacks callbacks;
    gpointer       user_data;
};

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

#define _NMLOG_DOMAIN      LOGD_IP4
#define _NMLOG_PREFIX_NAME "acd"
#define _NMLOG(level, ...)                                                     \
    G_STMT_START                                                               \
    {                                                                          \
        char _sbuf[64];                                                        \
                                                                               \
        nm_log((level),                                                        \
               _NMLOG_DOMAIN,                                                  \
               self && self->ifindex > 0                                       \
                   ? nm_platform_link_get_name(NM_PLATFORM_GET, self->ifindex) \
                   : NULL,                                                     \
               NULL,                                                           \
               "%s%s: " _NM_UTILS_MACRO_FIRST(__VA_ARGS__),                    \
               _NMLOG_PREFIX_NAME,                                             \
               self ? nm_sprintf_buf(_sbuf, "[%p,%d]", self, self->ifindex)    \
                    : "" _NM_UTILS_MACRO_REST(__VA_ARGS__));                   \
    }                                                                          \
    G_STMT_END

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

static const char *
_acd_event_to_string(unsigned int event)
{
    switch (event) {
    case N_ACD_EVENT_READY:
        return "ready";
    case N_ACD_EVENT_USED:
        return "used";
    case N_ACD_EVENT_DEFENDED:
        return "defended";
    case N_ACD_EVENT_CONFLICT:
        return "conflict";
    case N_ACD_EVENT_DOWN:
        return "down";
    }
    return NULL;
}

#define ACD_EVENT_TO_STRING_BUF_SIZE 50

static const char *
_acd_event_to_string_buf(unsigned event, char buffer[static ACD_EVENT_TO_STRING_BUF_SIZE])
{
    const char *s;

    s = _acd_event_to_string(event);
    if (s)
        return s;

    g_snprintf(buffer, ACD_EVENT_TO_STRING_BUF_SIZE, "(%u)", event);
    return buffer;
}

static const char *
acd_error_to_string(int error)
{
    if (error < 0)
        return nm_strerror_native(-error);

    switch (error) {
    case _N_ACD_E_SUCCESS:
        return "success";
    case N_ACD_E_PREEMPTED:
        return "preempted";
    case N_ACD_E_INVALID_ARGUMENT:
        return "invalid argument";
    }

    g_return_val_if_reached(NULL);
}

static int
acd_error_to_nmerr(int error, gboolean always_fail)
{
    if (error < 0)
        return -nm_errno_native(error);

    if (always_fail) {
        if (NM_IN_SET(error, N_ACD_E_PREEMPTED, N_ACD_E_INVALID_ARGUMENT))
            return -NME_UNSPEC;
        g_return_val_if_reached(-NME_UNSPEC);
    }

    /* so, @error is either zero (indicating success) or one
     * of the special status codes like N_ACD_E_*. In both cases,
     * return the positive value here. */
    if (NM_IN_SET(error, _N_ACD_E_SUCCESS, N_ACD_E_PREEMPTED, N_ACD_E_INVALID_ARGUMENT))
        return error;

    g_return_val_if_reached(error);
}

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

/**
 * nm_acd_manager_add_address:
 * @self: a #NMAcdManager
 * @address: an IP address
 *
 * Add @address to the list of IP addresses to probe.

 * Returns: %TRUE on success, %FALSE if the address was already in the list
 */
gboolean
nm_acd_manager_add_address(NMAcdManager *self, in_addr_t address)
{
    AddressInfo *info;

    g_return_val_if_fail(self, FALSE);
    g_return_val_if_fail(self->state == STATE_INIT, FALSE);

    if (g_hash_table_lookup(self->addresses, GUINT_TO_POINTER(address)))
        return FALSE;

    info          = g_slice_new0(AddressInfo);
    info->address = address;

    g_hash_table_insert(self->addresses, GUINT_TO_POINTER(address), info);

    return TRUE;
}

static gboolean
acd_event(int fd, GIOCondition condition, gpointer data)
{
    NMAcdManager *self = data;
    NAcdEvent *   event;
    AddressInfo * info;
    gboolean      emit_probe_terminated = FALSE;
    char          address_str[INET_ADDRSTRLEN];
    int           r;

    if (n_acd_dispatch(self->acd))
        return G_SOURCE_CONTINUE;

    while (!n_acd_pop_event(self->acd, &event) && event) {
        char          to_string_buffer[ACD_EVENT_TO_STRING_BUF_SIZE];
        gs_free char *hwaddr_str         = NULL;
        gboolean      check_probing_done = FALSE;

        switch (event->event) {
        case N_ACD_EVENT_READY:
            n_acd_probe_get_userdata(event->ready.probe, (void **) &info);
            info->duplicate = FALSE;
            if (self->state == STATE_ANNOUNCING) {
                /* fake probe ended, start announcing */
                r = n_acd_probe_announce(info->probe, N_ACD_DEFEND_ONCE);
                if (r) {
                    _LOGW("couldn't announce address %s on interface '%s': %s",
                          _nm_utils_inet4_ntop(info->address, address_str),
                          nm_platform_link_get_name(NM_PLATFORM_GET, self->ifindex),
                          acd_error_to_string(r));
                } else {
                    _LOGD("announcing address %s",
                          _nm_utils_inet4_ntop(info->address, address_str));
                }
            }
            check_probing_done = TRUE;
            break;
        case N_ACD_EVENT_USED:
            n_acd_probe_get_userdata(event->used.probe, (void **) &info);
            info->duplicate    = TRUE;
            check_probing_done = TRUE;
            break;
        case N_ACD_EVENT_DEFENDED:
            n_acd_probe_get_userdata(event->defended.probe, (void **) &info);
            _LOGD("defended address %s from host %s",
                  _nm_utils_inet4_ntop(info->address, address_str),
                  (hwaddr_str =
                       nm_utils_hwaddr_ntoa(event->defended.sender, event->defended.n_sender)));
            break;
        case N_ACD_EVENT_CONFLICT:
            n_acd_probe_get_userdata(event->conflict.probe, (void **) &info);
            _LOGW("conflict for address %s detected with host %s on interface '%s'",
                  _nm_utils_inet4_ntop(info->address, address_str),
                  (hwaddr_str =
                       nm_utils_hwaddr_ntoa(event->defended.sender, event->defended.n_sender)),
                  nm_platform_link_get_name(NM_PLATFORM_GET, self->ifindex));
            break;
        default:
            _LOGD("unhandled event '%s'", _acd_event_to_string_buf(event->event, to_string_buffer));
            break;
        }

        if (check_probing_done && self->state == STATE_PROBING
            && ++self->completed == g_hash_table_size(self->addresses)) {
            self->state           = STATE_PROBE_DONE;
            emit_probe_terminated = TRUE;
        }
    }

    if (emit_probe_terminated) {
        if (self->callbacks.probe_terminated_callback) {
            self->callbacks.probe_terminated_callback(self, self->user_data);
        }
    }

    return G_SOURCE_CONTINUE;
}

static gboolean
acd_probe_add(NMAcdManager *self, AddressInfo *info, guint64 timeout)
{
    NAcdProbeConfig *probe_config;
    int              r;
    char             sbuf[NM_UTILS_INET_ADDRSTRLEN];

    r = n_acd_probe_config_new(&probe_config);
    if (r) {
        _LOGW("could not create probe config for %s on interface '%s': %s",
              _nm_utils_inet4_ntop(info->address, sbuf),
              nm_platform_link_get_name(NM_PLATFORM_GET, self->ifindex),
              acd_error_to_string(r));
        return FALSE;
    }

    n_acd_probe_config_set_ip(probe_config, (struct in_addr){info->address});
    n_acd_probe_config_set_timeout(probe_config, timeout);

    r = n_acd_probe(self->acd, &info->probe, probe_config);
    if (r) {
        _LOGW("could not start probe for %s on interface '%s': %s",
              _nm_utils_inet4_ntop(info->address, sbuf),
              nm_platform_link_get_name(NM_PLATFORM_GET, self->ifindex),
              acd_error_to_string(r));
        n_acd_probe_config_free(probe_config);
        return FALSE;
    }

    n_acd_probe_set_userdata(info->probe, info);
    n_acd_probe_config_free(probe_config);

    return TRUE;
}

static int
acd_init(NMAcdManager *self)
{
    NAcdConfig *config;
    int         r;

    if (self->acd)
        return 0;

    r = n_acd_config_new(&config);
    if (r)
        return r;

    n_acd_config_set_ifindex(config, self->ifindex);
    n_acd_config_set_transport(config, N_ACD_TRANSPORT_ETHERNET);
    n_acd_config_set_mac(config, self->hwaddr, ETH_ALEN);

    r = n_acd_new(&self->acd, config);
    n_acd_config_free(config);
    return r;
}

/**
 * nm_acd_manager_start_probe:
 * @self: a #NMAcdManager
 * @timeout: maximum probe duration in milliseconds
 * @error: location to store error, or %NULL
 *
 * Start probing IP addresses for duplicates; when the probe terminates a
 * PROBE_TERMINATED signal is emitted.
 *
 * Returns: 0 on success or a negative NetworkManager error code (NME_*).
 */
int
nm_acd_manager_start_probe(NMAcdManager *self, guint timeout)
{
    GHashTableIter iter;
    AddressInfo *  info;
    gboolean       success = FALSE;
    int            fd, r;

    g_return_val_if_fail(self, FALSE);
    g_return_val_if_fail(self->state == STATE_INIT, FALSE);

    r = acd_init(self);
    if (r) {
        _LOGW("couldn't init ACD for probing on interface '%s': %s",
              nm_platform_link_get_name(NM_PLATFORM_GET, self->ifindex),
              acd_error_to_string(r));
        return acd_error_to_nmerr(r, TRUE);
    }

    self->completed = 0;

    g_hash_table_iter_init(&iter, self->addresses);
    while (g_hash_table_iter_next(&iter, NULL, (gpointer *) &info))
        success |= acd_probe_add(self, info, timeout);

    if (success)
        self->state = STATE_PROBING;

    nm_assert(!self->event_source);
    n_acd_get_fd(self->acd, &fd);
    self->event_source =
        nm_g_unix_fd_source_new(fd, G_IO_IN, G_PRIORITY_DEFAULT, acd_event, self, NULL);
    g_source_attach(self->event_source, NULL);

    return success ? 0 : -NME_UNSPEC;
}

/**
 * nm_acd_manager_check_address:
 * @self: a #NMAcdManager
 * @address: an IP address
 *
 * Check if an IP address is duplicate. @address must have been added with
 * nm_acd_manager_add_address().
 *
 * Returns: %TRUE if the address is not duplicate, %FALSE otherwise
 */
gboolean
nm_acd_manager_check_address(NMAcdManager *self, in_addr_t address)
{
    AddressInfo *info;

    g_return_val_if_fail(self, FALSE);
    g_return_val_if_fail(NM_IN_SET(self->state, STATE_INIT, STATE_PROBE_DONE), FALSE);

    info = g_hash_table_lookup(self->addresses, GUINT_TO_POINTER(address));
    g_return_val_if_fail(info, FALSE);

    return !info->duplicate;
}

/**
 * nm_acd_manager_announce_addresses:
 * @self: a #NMAcdManager
 *
 * Start announcing addresses.
 *
 * Returns: a negative NetworkManager error number or zero on success.
 */
int
nm_acd_manager_announce_addresses(NMAcdManager *self)
{
    GHashTableIter iter;
    AddressInfo *  info;
    int            r;
    int            fd;
    gboolean       success = TRUE;

    r = acd_init(self);
    if (r) {
        _LOGW("couldn't init ACD for announcing addresses on interface '%s': %s",
              nm_platform_link_get_name(NM_PLATFORM_GET, self->ifindex),
              acd_error_to_string(r));
        return acd_error_to_nmerr(r, TRUE);
    }

    if (self->state == STATE_INIT) {
        /* n-acd can't announce without probing, therefore let's
         * start a fake probe with zero timeout and then perform
         * the announcement. */
        g_hash_table_iter_init(&iter, self->addresses);
        while (g_hash_table_iter_next(&iter, NULL, (gpointer *) &info)) {
            if (!acd_probe_add(self, info, 0))
                success = FALSE;
        }
        self->state = STATE_ANNOUNCING;
    } else if (self->state == STATE_ANNOUNCING) {
        char sbuf[NM_UTILS_INET_ADDRSTRLEN];

        g_hash_table_iter_init(&iter, self->addresses);
        while (g_hash_table_iter_next(&iter, NULL, (gpointer *) &info)) {
            if (info->duplicate)
                continue;
            r = n_acd_probe_announce(info->probe, N_ACD_DEFEND_ONCE);
            if (r) {
                _LOGW("couldn't announce address %s on interface '%s': %s",
                      _nm_utils_inet4_ntop(info->address, sbuf),
                      nm_platform_link_get_name(NM_PLATFORM_GET, self->ifindex),
                      acd_error_to_string(r));
                success = FALSE;
            } else
                _LOGD("announcing address %s", _nm_utils_inet4_ntop(info->address, sbuf));
        }
    }

    if (!self->event_source) {
        n_acd_get_fd(self->acd, &fd);
        self->event_source =
            nm_g_unix_fd_source_new(fd, G_IO_IN, G_PRIORITY_DEFAULT, acd_event, self, NULL);
        g_source_attach(self->event_source, NULL);
    }

    return success ? 0 : -NME_UNSPEC;
}

static void
destroy_address_info(gpointer data)
{
    AddressInfo *info = (AddressInfo *) data;

    n_acd_probe_free(info->probe);

    g_slice_free(AddressInfo, info);
}

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

NMAcdManager *
nm_acd_manager_new(int                   ifindex,
                   const guint8 *        hwaddr,
                   guint                 hwaddr_len,
                   const NMAcdCallbacks *callbacks,
                   gpointer              user_data)
{
    NMAcdManager *self;

    g_return_val_if_fail(ifindex > 0, NULL);
    g_return_val_if_fail(hwaddr, NULL);
    g_return_val_if_fail(hwaddr_len == ETH_ALEN, NULL);

    self = g_slice_new0(NMAcdManager);

    if (callbacks)
        self->callbacks = *callbacks;
    self->user_data = user_data;

    self->addresses = g_hash_table_new_full(nm_direct_hash, NULL, NULL, destroy_address_info);
    self->state     = STATE_INIT;
    self->ifindex   = ifindex;
    memcpy(self->hwaddr, hwaddr, ETH_ALEN);
    return self;
}

void
nm_acd_manager_free(NMAcdManager *self)
{
    g_return_if_fail(self);

    if (self->callbacks.user_data_destroy)
        self->callbacks.user_data_destroy(self->user_data);

    nm_clear_pointer(&self->addresses, g_hash_table_destroy);
    nm_clear_g_source_inst(&self->event_source);
    nm_clear_pointer(&self->acd, n_acd_unref);

    g_slice_free(NMAcdManager, self);
}