test_overlap.py

from sqlalchemy import event
from sqlalchemy import DDL

def mysql_cidr_overlap(engine, metadata):
    @event.listens_for(metadata, "after_create")
    def _create_mysql_proc(target, connection, **kw):
        if connection.engine.name != 'mysql':
            return

        if connection.scalar(
            "SELECT ROUTINE_NAME FROM INFORMATION_SCHEMA.ROUTINES "
            "WHERE ROUTINE_TYPE='FUNCTION' AND ROUTINE_SCHEMA=DATABASE() AND "
            "ROUTINE_NAME=%s",
            ("cidr_overlap", )
        ):
            connection.execute("DROP FUNCTION cidr_overlap")

        connection.execute(
            DDL("""
        CREATE FUNCTION cidr_overlap (cidr1 varchar(64), cidr2 varchar(64))
        RETURNS TINYINT
        BEGIN
        DECLARE ipv6_1, ipv6_2, bitmask INT;
        DECLARE division, modulo, netmask SMALLINT;
        DECLARE tmp TINYINT DEFAULT 1;
        SET netmask = least(
                    cast(substring_index(cidr1, '/', -1) as signed integer),
                    cast(substring_index(cidr2, '/', -1) as signed integer));
        SET division = netmask DIV 16;
        SET modulo = netmask % 16;
        masking : WHILE (division >= 0) DO
            SET ipv6_1 = CONV(substring_index(substring_index
                                    (cidr1, ':', tmp), ':', -1), 16, 10);
            SET ipv6_2 = CONV(substring_index(substring_index
                                    (cidr2, ':', tmp), ':', -1), 16, 10);
            IF (division != 0) THEN
                IF (ipv6_1 != ipv6_2) THEN
                    RETURN 0;
                    LEAVE masking;
                END IF;
            ELSE
                SET bitmask = pow(2, (16 - modulo)) - 1;
                RETURN ipv6_1 & ~bitmask = ipv6_2 & ~bitmask;
            END IF;
            SET tmp = tmp + 1;
            SET division = division - 1;
        END WHILE masking;
        END
        """)
        )




if __name__ == '__main__':
    from sqlalchemy import Column, Integer, String, create_engine, func
    from sqlalchemy.ext.declarative import declarative_base
    from sqlalchemy.orm import Session, aliased
    from sqlalchemy import event

    Base = declarative_base()

    class A(Base):
        __tablename__ = 'a'
        id = Column(Integer, primary_key=True)
        cidr = Column(String(30))

    event.listen(
        A.__table__, "after_create",
        DDL("""
    CREATE TRIGGER no_overlap_cidr_a
    BEFORE INSERT ON a
    FOR EACH ROW
    BEGIN
      DECLARE msg VARCHAR(200);
      IF (EXISTS(SELECT * FROM a WHERE cidr_overlap(cidr, NEW.cidr))) THEN
        SET msg = CONCAT(
            'inserted subnet ', NEW.subnet,
            ' conflicts with existing subnets');
        SIGNAL sqlstate '45000'
            SET MESSAGE_TEXT = msg;
      END IF;
    END
        """)
    )

    e = create_engine("mysql://root:abc123@localhost/test", echo=True)

    mysql_cidr_overlap(e, Base.metadata)

    Base.metadata.drop_all(e)
    Base.metadata.create_all(e)

    s = Session(e)

    with s.begin_nested():
        s.add(A(cidr='fd04:901d:e7de:abcd::/64'))

    with s.begin_nested():
        s.add(A(cidr='fd04:901d:e7de:abce::/64'))

    try:
        with s.begin_nested():
            s.add(A(cidr='fd04:901d:e7de:abcd::/65'))
    except Exception as e:
        print "Error! %s" % e

    s.commit()

    a1, a2 = aliased(A), aliased(A)

    # return all non-overlapping CIDR pairs
    for a, b in s.query(a1.subnet, a2.subnet).\
        filter(~func.cidr_overlap(a1.subnet, a2.subnet)).\
            filter(a1.id > a2.id):
            print a, b



sfsfsfsfs