/*
 *  net/dccp/ccid.c
 *
 *  An implementation of the DCCP protocol
 *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 *
 *  CCID infrastructure
 *
 *      This program is free software; you can redistribute it and/or modify it
 *      under the terms of the GNU General Public License version 2 as
 *      published by the Free Software Foundation.
 */

#include <linux/slab.h>

#include "ccid.h"
#include "ccids/lib/tfrc.h"

static struct ccid_operations *ccids[] = {
        &ccid2_ops,
#ifdef CONFIG_IP_DCCP_CCID3
        &ccid3_ops,
#endif
};

static struct ccid_operations *ccid_by_number(const u8 id)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(ccids); i++)
                if (ccids[i]->ccid_id == id)
                        return ccids[i];
        return NULL;
}

/* check that up to @array_len members in @ccid_array are supported */
bool ccid_support_check(u8 const *ccid_array, u8 array_len)
{
        while (array_len > 0)
                if (ccid_by_number(ccid_array[--array_len]) == NULL)
                        return false;
        return true;
}

/**
 * ccid_get_builtin_ccids  -  Populate a list of built-in CCIDs
 * @ccid_array: pointer to copy into
 * @array_len: value to return length into
 *
 * This function allocates memory - caller must see that it is freed after use.
 */
int ccid_get_builtin_ccids(u8 **ccid_array, u8 *array_len)
{
        *ccid_array = kmalloc(ARRAY_SIZE(ccids), gfp_any());
        if (*ccid_array == NULL)
                return -ENOBUFS;

        for (*array_len = 0; *array_len < ARRAY_SIZE(ccids); *array_len += 1)
                (*ccid_array)[*array_len] = ccids[*array_len]->ccid_id;
        return 0;
}

int ccid_getsockopt_builtin_ccids(struct sock *sk, int len,
                                  char __user *optval, int __user *optlen)
{
        u8 *ccid_array, array_len;
        int err = 0;

        if (ccid_get_builtin_ccids(&ccid_array, &array_len))
                return -ENOBUFS;

        if (put_user(array_len, optlen))
                err = -EFAULT;
        else if (len > 0 && copy_to_user(optval, ccid_array,
                                         len > array_len ? array_len : len))
                err = -EFAULT;

        kfree(ccid_array);
        return err;
}

static struct kmem_cache *ccid_kmem_cache_create(int obj_size, char *slab_name_fmt, const char *fmt,...)
{
        struct kmem_cache *slab;
        va_list args;

        va_start(args, fmt);
        vsnprintf(slab_name_fmt, CCID_SLAB_NAME_LENGTH, fmt, args);
        va_end(args);

        slab = kmem_cache_create(slab_name_fmt, sizeof(struct ccid) + obj_size, 0,
                                 SLAB_HWCACHE_ALIGN, NULL);
        return slab;
}

static void ccid_kmem_cache_destroy(struct kmem_cache *slab)
{
        if (slab != NULL)
                kmem_cache_destroy(slab);
}

static int ccid_activate(struct ccid_operations *ccid_ops)
{
        int err = -ENOBUFS;

        ccid_ops->ccid_hc_rx_slab =
                        ccid_kmem_cache_create(ccid_ops->ccid_hc_rx_obj_size,
                                               ccid_ops->ccid_hc_rx_slab_name,
                                               "ccid%u_hc_rx_sock",
                                               ccid_ops->ccid_id);
        if (ccid_ops->ccid_hc_rx_slab == NULL)
                goto out;

        ccid_ops->ccid_hc_tx_slab =
                        ccid_kmem_cache_create(ccid_ops->ccid_hc_tx_obj_size,
                                               ccid_ops->ccid_hc_tx_slab_name,
                                               "ccid%u_hc_tx_sock",
                                               ccid_ops->ccid_id);
        if (ccid_ops->ccid_hc_tx_slab == NULL)
                goto out_free_rx_slab;

        pr_info("DCCP: Activated CCID %d (%s)\n",
                ccid_ops->ccid_id, ccid_ops->ccid_name);
        err = 0;
out:
        return err;
out_free_rx_slab:
        ccid_kmem_cache_destroy(ccid_ops->ccid_hc_rx_slab);
        ccid_ops->ccid_hc_rx_slab = NULL;
        goto out;
}

static void ccid_deactivate(struct ccid_operations *ccid_ops)
{
        ccid_kmem_cache_destroy(ccid_ops->ccid_hc_tx_slab);
        ccid_ops->ccid_hc_tx_slab = NULL;
        ccid_kmem_cache_destroy(ccid_ops->ccid_hc_rx_slab);
        ccid_ops->ccid_hc_rx_slab = NULL;

        pr_info("DCCP: Deactivated CCID %d (%s)\n",
                ccid_ops->ccid_id, ccid_ops->ccid_name);
}

struct ccid *ccid_new(const u8 id, struct sock *sk, bool rx)
{
        struct ccid_operations *ccid_ops = ccid_by_number(id);
        struct ccid *ccid = NULL;

        if (ccid_ops == NULL)
                goto out;

        ccid = kmem_cache_alloc(rx ? ccid_ops->ccid_hc_rx_slab :
                                     ccid_ops->ccid_hc_tx_slab, gfp_any());
        if (ccid == NULL)
                goto out;
        ccid->ccid_ops = ccid_ops;
        if (rx) {
                memset(ccid + 1, 0, ccid_ops->ccid_hc_rx_obj_size);
                if (ccid->ccid_ops->ccid_hc_rx_init != NULL &&
                    ccid->ccid_ops->ccid_hc_rx_init(ccid, sk) != 0)
                        goto out_free_ccid;
        } else {
                memset(ccid + 1, 0, ccid_ops->ccid_hc_tx_obj_size);
                if (ccid->ccid_ops->ccid_hc_tx_init != NULL &&
                    ccid->ccid_ops->ccid_hc_tx_init(ccid, sk) != 0)
                        goto out_free_ccid;
        }
out:
        return ccid;
out_free_ccid:
        kmem_cache_free(rx ? ccid_ops->ccid_hc_rx_slab :
                        ccid_ops->ccid_hc_tx_slab, ccid);
        ccid = NULL;
        goto out;
}

void ccid_hc_rx_delete(struct ccid *ccid, struct sock *sk)
{
        if (ccid != NULL) {
                if (ccid->ccid_ops->ccid_hc_rx_exit != NULL)
                        ccid->ccid_ops->ccid_hc_rx_exit(sk);
                kmem_cache_free(ccid->ccid_ops->ccid_hc_rx_slab, ccid);
        }
}

void ccid_hc_tx_delete(struct ccid *ccid, struct sock *sk)
{
        if (ccid != NULL) {
                if (ccid->ccid_ops->ccid_hc_tx_exit != NULL)
                        ccid->ccid_ops->ccid_hc_tx_exit(sk);
                kmem_cache_free(ccid->ccid_ops->ccid_hc_tx_slab, ccid);
        }
}

int __init ccid_initialize_builtins(void)
{
        int i, err = tfrc_lib_init();

        if (err)
                return err;

        for (i = 0; i < ARRAY_SIZE(ccids); i++) {
                err = ccid_activate(ccids[i]);
                if (err)
                        goto unwind_registrations;
        }
        return 0;

unwind_registrations:
        while(--i >= 0)
                ccid_deactivate(ccids[i]);
        tfrc_lib_exit();
        return err;
}

void ccid_cleanup_builtins(void)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(ccids); i++)
                ccid_deactivate(ccids[i]);
        tfrc_lib_exit();
}