SUMMARY = "Updates the NVD CVE database"
LICENSE = "MIT"

INHIBIT_DEFAULT_DEPS = "1"
PACKAGES = ""

inherit nopackages

deltask do_fetch
deltask do_unpack
deltask do_patch
deltask do_configure
deltask do_compile
deltask do_install
deltask do_populate_sysroot

python do_populate_cve_db() {
    """
    Update NVD database with json data feed
    """

    import sqlite3, urllib3, shutil, gzip, re
    from datetime import date

    BASE_URL = "https://nvd.nist.gov/feeds/json/cve/1.0/nvdcve-1.0-"
    YEAR_START = 2002
    JSON_TMPFILE = d.getVar("CVE_CHECK_DB_DIR") + '/nvd.json.gz'

    # Connect to database
    db_file = d.getVar("CVE_CHECK_DB_FILE")
    conn = sqlite3.connect(db_file)
    c = conn.cursor()

    initialize_db(c)

    http = urllib3.PoolManager()

    for year in range(YEAR_START, date.today().year + 1):
        year_url = BASE_URL + str(year)
        meta_url = year_url + ".meta"
        json_url = year_url + ".json.gz"

        # Retrieve meta last modified date
        with http.request('GET', meta_url, preload_content=False) as r:
            date_line = str(r.data.splitlines()[0])
            last_modified = re.search('lastModifiedDate:(.*)', date_line).group(1)

        # Compare with current db last modified date
        c.execute("select DATE from META where YEAR = '%d'" % year)
        meta = c.fetchone()
        if not meta or meta[0] != last_modified:
            # Update db with current year json file
            with http.request('GET', json_url, preload_content=False) as r, open(JSON_TMPFILE, 'wb') as tmpfile:
                shutil.copyfileobj(r, tmpfile)
            with gzip.open(JSON_TMPFILE, 'rt') as jsonfile:
                update_db(c, jsonfile)
            c.execute("insert or replace into META values (?, ?)",
                    [year, last_modified])

    conn.commit()
    conn.close()

    with open(d.getVar("CVE_CHECK_TMP_FILE"), 'a'):
        os.utime(d.getVar("CVE_CHECK_TMP_FILE"), None)
}

# DJB2 hash algorithm
def hash_djb2(s):
    hash = 5381
    for x in s:
        hash = (( hash << 5) + hash) + ord(x)

    return hash & 0xFFFFFFFF

def initialize_db(c):
    c.execute("CREATE TABLE IF NOT EXISTS META (YEAR INTEGER UNIQUE, DATE TEXT)")
    c.execute("CREATE TABLE IF NOT EXISTS NVD (ID TEXT UNIQUE, SUMMARY TEXT, \
        SCOREV2 TEXT, SCOREV3 TEXT, MODIFIED INTEGER, VECTOR TEXT)")
    c.execute("CREATE TABLE IF NOT EXISTS PRODUCTS (HASH INTEGER UNIQUE, ID TEXT, \
        VENDOR TEXT, PRODUCT TEXT, VERSION TEXT, OPERATOR TEXT)")
    c.execute("CREATE INDEX IF NOT EXISTS PRODUCT_IDX ON PRODUCTS \
        (PRODUCT, VERSION)")

def update_db(c, json_filename):
    import json
    root = json.load(json_filename)

    for elt in root['CVE_Items']:
        if not elt['impact']:
            continue

        cveId = elt['cve']['CVE_data_meta']['ID']
        cveDesc = elt['cve']['description']['description_data'][0]['value']
        date = elt['lastModifiedDate']
        accessVector = elt['impact']['baseMetricV2']['cvssV2']['accessVector']
        cvssv2 = elt['impact']['baseMetricV2']['cvssV2']['baseScore']

        try:
            cvssv3 = elt['impact']['baseMetricV3']['cvssV3']['baseScore']
        except:
            cvssv3 = 0.0

        c.execute("insert or replace into NVD values (?, ?, ?, ?, ?, ?)",
                [cveId, cveDesc, cvssv2, cvssv3, date, accessVector])

        for vendor in elt['cve']['affects']['vendor']['vendor_data']:
            for product in vendor['product']['product_data']:
                for version in product['version']['version_data']:
                    product_str = cveId+vendor['vendor_name']+product['product_name']+version['version_value']
                    hashstr = hash_djb2(product_str)
                    c.execute("insert or replace into PRODUCTS values (?, ?, ?, ?, ?, ?)",
                            [ hashstr, cveId, vendor['vendor_name'],
                                product['product_name'], version['version_value'],
                                version['version_affected']])


addtask do_populate_cve_db before do_cve_check
do_populate_cve_db[nostamp] = "1"

EXCLUDE_FROM_WORLD = "1"