cs.c

/*
 * Copyright (C) 2016 Wentao Shang
 *
 * This file is subject to the terms and conditions of the GNU Lesser
 * General Public License v2.1. See the file LICENSE in the top level
 * directory for more details.
 */

/**
 * @ingroup     net_ndn
 * @{
 *
 * @file
 *
 * @author  Wentao Shang <wentaoshang@gmail.com>
 */

#include "cs.h"
#include "encoding/interest.h"
#include "encoding/data.h"

#include <utlist.h>
#include <debug.h>

#include <assert.h>
#include <stdlib.h>

static ndn_cs_entry_t *_cs;
static int _cs_size;

#define MAX_CS_SIZE 24000

static void _ndn_cs_remove(ndn_cs_entry_t* entry)
{
    DL_DELETE(_cs, entry);
    _cs_size -= entry->data->block.len;
    DEBUG("ndn: remove cs entry (_cs_size=%d)\n", _cs_size);
    ndn_shared_block_release(entry->data);
    free(entry);
}

int ndn_cs_add(ndn_shared_block_t* data)
{
    assert(data != NULL);

    if (_cs_size + data->block.len > MAX_CS_SIZE) {
        if (data->block.len > (MAX_CS_SIZE >> 1)) {
            DEBUG("ndn: data packet too big\n");
            return -1;
        }

        assert(_cs != NULL);
        // clean up cs by half
        while (_cs_size + data->block.len > (MAX_CS_SIZE >> 1)) {
            // remove front entries (FIFO)
            _ndn_cs_remove(_cs);
        }
    }

    // allocate new entry
    ndn_cs_entry_t *entry = (ndn_cs_entry_t*)malloc(sizeof(ndn_cs_entry_t));
    if (entry == NULL) {
        DEBUG("ndn: cannot allocate pit entry\n");
        return -1;
    }

    entry->data = ndn_shared_block_copy(data);
    entry->prev = entry->next = NULL;

    DL_PREPEND(_cs, entry);
    _cs_size += entry->data->block.len;
    DEBUG("ndn: add new cs entry (_cs_size=%d)\n", _cs_size);
    return 0;
}

ndn_shared_block_t* ndn_cs_match(ndn_block_t* interest)
{
    ndn_block_t iname;
    int r = ndn_interest_get_name(interest, &iname);
    if (r != 0) {
        DEBUG("ndn: cannot get name from interest for cs matching\n");
        return NULL;
    }

    ndn_cs_entry_t *entry;
    DL_FOREACH(_cs, entry) {
        ndn_block_t dname;
        r = ndn_data_get_name(&entry->data->block, &dname);
        assert(r == 0);

        r = ndn_name_compare_block(&iname, &dname);
        if (r == -2 || r == 0) {
            // either iname is a prefix of dname, or they are the same
            return ndn_shared_block_copy(entry->data);
        }
    }
    return NULL;
}

void ndn_cs_init(void)
{
    _cs = NULL;
    _cs_size = 0;
}


/** @} */