/*
 * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
 * (a.k.a. Fault Tolerance or Continuous Replication)
 *
 * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
 * Copyright (c) 2016 FUJITSU LIMITED
 * Copyright (c) 2016 Intel Corporation
 *
 * Author: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or
 * later.  See the COPYING file in the top-level directory.
 */

#include "qemu/osdep.h"
#include "qemu/error-report.h"
#include "trace.h"
#include "qemu-common.h"
#include "qapi/qmp/qerror.h"
#include "qapi/error.h"
#include "net/net.h"
#include "qom/object_interfaces.h"
#include "qemu/iov.h"
#include "qom/object.h"
#include "qemu/typedefs.h"
#include "net/queue.h"
#include "sysemu/char.h"
#include "qemu/sockets.h"
#include "qapi-visit.h"
#include "net/colo.h"

#define TYPE_COLO_COMPARE "colo-compare"
#define COLO_COMPARE(obj) \
    OBJECT_CHECK(CompareState, (obj), TYPE_COLO_COMPARE)

#define MAX_QUEUE_SIZE 1024

/*
  + CompareState ++
  |               |
  +---------------+   +---------------+         +---------------+
  |conn list      +--->conn           +--------->conn           |
  +---------------+   +---------------+         +---------------+
  |               |     |           |             |          |
  +---------------+ +---v----+  +---v----+    +---v----+ +---v----+
                    |primary |  |secondary    |primary | |secondary
                    |packet  |  |packet  +    |packet  | |packet  +
                    +--------+  +--------+    +--------+ +--------+
                        |           |             |          |
                    +---v----+  +---v----+    +---v----+ +---v----+
                    |primary |  |secondary    |primary | |secondary
                    |packet  |  |packet  +    |packet  | |packet  +
                    +--------+  +--------+    +--------+ +--------+
                        |           |             |          |
                    +---v----+  +---v----+    +---v----+ +---v----+
                    |primary |  |secondary    |primary | |secondary
                    |packet  |  |packet  +    |packet  | |packet  +
                    +--------+  +--------+    +--------+ +--------+
*/
typedef struct CompareState {
    Object parent;

    char *pri_indev;
    char *sec_indev;
    char *outdev;
    CharDriverState *chr_pri_in;
    CharDriverState *chr_sec_in;
    CharDriverState *chr_out;
    SocketReadState pri_rs;
    SocketReadState sec_rs;

    /* connection list: the connections belonged to this NIC could be found
     * in this list.
     * element type: Connection
     */
    GQueue conn_list;
    /* hashtable to save connection */
    GHashTable *connection_track_table;
} CompareState;

typedef struct CompareClass {
    ObjectClass parent_class;
} CompareClass;

typedef struct CompareChardevProps {
    bool is_socket;
} CompareChardevProps;

enum {
    PRIMARY_IN = 0,
    SECONDARY_IN,
};

static int compare_chr_send(CharDriverState *out,
                            const uint8_t *buf,
                            uint32_t size);

/*
 * Return 0 on success, if return -1 means the pkt
 * is unsupported(arp and ipv6) and will be sent later
 */
static int packet_enqueue(CompareState *s, int mode)
{
    ConnectionKey key;
    Packet *pkt = NULL;
    Connection *conn;

    if (mode == PRIMARY_IN) {
        pkt = packet_new(s->pri_rs.buf, s->pri_rs.packet_len);
    } else {
        pkt = packet_new(s->sec_rs.buf, s->sec_rs.packet_len);
    }

    if (parse_packet_early(pkt)) {
        packet_destroy(pkt, NULL);
        pkt = NULL;
        return -1;
    }
    fill_connection_key(pkt, &key);

    conn = connection_get(s->connection_track_table,
                          &key,
                          &s->conn_list);

    if (!conn->processing) {
        g_queue_push_tail(&s->conn_list, conn);
        conn->processing = true;
    }

    if (mode == PRIMARY_IN) {
        if (g_queue_get_length(&conn->primary_list) <=
                               MAX_QUEUE_SIZE) {
            g_queue_push_tail(&conn->primary_list, pkt);
        } else {
            error_report("colo compare primary queue size too big,"
                         "drop packet");
        }
    } else {
        if (g_queue_get_length(&conn->secondary_list) <=
                               MAX_QUEUE_SIZE) {
            g_queue_push_tail(&conn->secondary_list, pkt);
        } else {
            error_report("colo compare secondary queue size too big,"
                         "drop packet");
        }
    }

    return 0;
}

static int compare_chr_send(CharDriverState *out,
                            const uint8_t *buf,
                            uint32_t size)
{
    int ret = 0;
    uint32_t len = htonl(size);

    if (!size) {
        return 0;
    }

    ret = qemu_chr_fe_write_all(out, (uint8_t *)&len, sizeof(len));
    if (ret != sizeof(len)) {
        goto err;
    }

    ret = qemu_chr_fe_write_all(out, (uint8_t *)buf, size);
    if (ret != size) {
        goto err;
    }

    return 0;

err:
    return ret < 0 ? ret : -EIO;
}

static char *compare_get_pri_indev(Object *obj, Error **errp)
{
    CompareState *s = COLO_COMPARE(obj);

    return g_strdup(s->pri_indev);
}

static void compare_set_pri_indev(Object *obj, const char *value, Error **errp)
{
    CompareState *s = COLO_COMPARE(obj);

    g_free(s->pri_indev);
    s->pri_indev = g_strdup(value);
}

static char *compare_get_sec_indev(Object *obj, Error **errp)
{
    CompareState *s = COLO_COMPARE(obj);

    return g_strdup(s->sec_indev);
}

static void compare_set_sec_indev(Object *obj, const char *value, Error **errp)
{
    CompareState *s = COLO_COMPARE(obj);

    g_free(s->sec_indev);
    s->sec_indev = g_strdup(value);
}

static char *compare_get_outdev(Object *obj, Error **errp)
{
    CompareState *s = COLO_COMPARE(obj);

    return g_strdup(s->outdev);
}

static void compare_set_outdev(Object *obj, const char *value, Error **errp)
{
    CompareState *s = COLO_COMPARE(obj);

    g_free(s->outdev);
    s->outdev = g_strdup(value);
}

static void compare_pri_rs_finalize(SocketReadState *pri_rs)
{
    CompareState *s = container_of(pri_rs, CompareState, pri_rs);

    if (packet_enqueue(s, PRIMARY_IN)) {
        trace_colo_compare_main("primary: unsupported packet in");
        compare_chr_send(s->chr_out, pri_rs->buf, pri_rs->packet_len);
    }
}

static void compare_sec_rs_finalize(SocketReadState *sec_rs)
{
    CompareState *s = container_of(sec_rs, CompareState, sec_rs);

    if (packet_enqueue(s, SECONDARY_IN)) {
        trace_colo_compare_main("secondary: unsupported packet in");
    }
}

static int compare_chardev_opts(void *opaque,
                                const char *name, const char *value,
                                Error **errp)
{
    CompareChardevProps *props = opaque;

    if (strcmp(name, "backend") == 0 &&
        strcmp(value, "socket") == 0) {
        props->is_socket = true;
        return 0;
    } else if (strcmp(name, "host") == 0 ||
              (strcmp(name, "port") == 0) ||
              (strcmp(name, "server") == 0) ||
              (strcmp(name, "wait") == 0) ||
              (strcmp(name, "path") == 0)) {
        return 0;
    } else {
        error_setg(errp,
                   "COLO-compare does not support a chardev with option %s=%s",
                   name, value);
        return -1;
    }
}

/*
 * Return 0 is success.
 * Return 1 is failed.
 */
static int find_and_check_chardev(CharDriverState **chr,
                                  char *chr_name,
                                  Error **errp)
{
    CompareChardevProps props;

    *chr = qemu_chr_find(chr_name);
    if (*chr == NULL) {
        error_setg(errp, "Device '%s' not found",
                   chr_name);
        return 1;
    }

    memset(&props, 0, sizeof(props));
    if (qemu_opt_foreach((*chr)->opts, compare_chardev_opts, &props, errp)) {
        return 1;
    }

    if (!props.is_socket) {
        error_setg(errp, "chardev \"%s\" is not a tcp socket",
                   chr_name);
        return 1;
    }
    return 0;
}

/*
 * Called from the main thread on the primary
 * to setup colo-compare.
 */
static void colo_compare_complete(UserCreatable *uc, Error **errp)
{
    CompareState *s = COLO_COMPARE(uc);

    if (!s->pri_indev || !s->sec_indev || !s->outdev) {
        error_setg(errp, "colo compare needs 'primary_in' ,"
                   "'secondary_in','outdev' property set");
        return;
    } else if (!strcmp(s->pri_indev, s->outdev) ||
               !strcmp(s->sec_indev, s->outdev) ||
               !strcmp(s->pri_indev, s->sec_indev)) {
        error_setg(errp, "'indev' and 'outdev' could not be same "
                   "for compare module");
        return;
    }

    if (find_and_check_chardev(&s->chr_pri_in, s->pri_indev, errp)) {
        return;
    }

    if (find_and_check_chardev(&s->chr_sec_in, s->sec_indev, errp)) {
        return;
    }

    if (find_and_check_chardev(&s->chr_out, s->outdev, errp)) {
        return;
    }

    qemu_chr_fe_claim_no_fail(s->chr_pri_in);

    qemu_chr_fe_claim_no_fail(s->chr_sec_in);

    qemu_chr_fe_claim_no_fail(s->chr_out);

    net_socket_rs_init(&s->pri_rs, compare_pri_rs_finalize);
    net_socket_rs_init(&s->sec_rs, compare_sec_rs_finalize);

    g_queue_init(&s->conn_list);

    s->connection_track_table = g_hash_table_new_full(connection_key_hash,
                                                      connection_key_equal,
                                                      g_free,
                                                      connection_destroy);

    return;
}

static void colo_compare_class_init(ObjectClass *oc, void *data)
{
    UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);

    ucc->complete = colo_compare_complete;
}

static void colo_compare_init(Object *obj)
{
    object_property_add_str(obj, "primary_in",
                            compare_get_pri_indev, compare_set_pri_indev,
                            NULL);
    object_property_add_str(obj, "secondary_in",
                            compare_get_sec_indev, compare_set_sec_indev,
                            NULL);
    object_property_add_str(obj, "outdev",
                            compare_get_outdev, compare_set_outdev,
                            NULL);
}

static void colo_compare_finalize(Object *obj)
{
    CompareState *s = COLO_COMPARE(obj);

    if (s->chr_pri_in) {
        qemu_chr_add_handlers(s->chr_pri_in, NULL, NULL, NULL, NULL);
        qemu_chr_fe_release(s->chr_pri_in);
    }
    if (s->chr_sec_in) {
        qemu_chr_add_handlers(s->chr_sec_in, NULL, NULL, NULL, NULL);
        qemu_chr_fe_release(s->chr_sec_in);
    }
    if (s->chr_out) {
        qemu_chr_fe_release(s->chr_out);
    }

    g_queue_free(&s->conn_list);

    g_free(s->pri_indev);
    g_free(s->sec_indev);
    g_free(s->outdev);
}

static const TypeInfo colo_compare_info = {
    .name = TYPE_COLO_COMPARE,
    .parent = TYPE_OBJECT,
    .instance_size = sizeof(CompareState),
    .instance_init = colo_compare_init,
    .instance_finalize = colo_compare_finalize,
    .class_size = sizeof(CompareClass),
    .class_init = colo_compare_class_init,
    .interfaces = (InterfaceInfo[]) {
        { TYPE_USER_CREATABLE },
        { }
    }
};

static void register_types(void)
{
    type_register_static(&colo_compare_info);
}

type_init(register_types);