test_prefixlen.cpp

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#include "test_common.hpp"
#include <iostream>
#include <string>
 
#include <openvpn/common/exception.hpp>
 
#include <openvpn/addr/ip.hpp>
 
using namespace openvpn;
 
OPENVPN_SIMPLE_EXCEPTION(ipv4_bad_prefix_len);
OPENVPN_SIMPLE_EXCEPTION(ipv4_bad_netmask);
 
inline IPv4::Addr::base_type prefix_len_to_netmask_unchecked(const unsigned int prefix_len)
{
    return ~((1u << (32 - prefix_len)) - 1);
}
 
inline IPv4::Addr::base_type prefix_len_to_netmask(const unsigned int prefix_len)
{
    if (prefix_len >= 1 && prefix_len <= 32)
        return prefix_len_to_netmask_unchecked(prefix_len);
    else
        throw ipv4_bad_prefix_len();
}
 
inline int prefix_len(const IPv4::Addr::base_type mask)
{
    if (mask != ~0u)
    {
        unsigned int high = 32;
        unsigned int low = 1;
        for (unsigned int i = 0; i < 5; ++i)
        {
            const unsigned int mid = (high + low) / 2;
            const IPv4::Addr::base_type test = prefix_len_to_netmask_unchecked(mid);
            if (mask == test)
                return mid;
            else if (mask > test)
                low = mid;
            else
                high = mid;
        }
        return -1;
    }
    else
        return 32;
}
 
TEST(IPAddr, test32)
{
    for (unsigned int i = 1; i <= 32; ++i)
    {
        const IPv4::Addr::base_type mask = prefix_len_to_netmask(i);
        const int pl = prefix_len(mask);
        ASSERT_EQ(pl, (int)i);
 
        // IPv4::Addr a = IPv4::Addr::from_uint32(mask);
        // std::cout << i << ' ' << pl << ' ' << a << std::endl;
    }
}
 
TEST(IPAddr, prefixlen)
{
    for (unsigned int i = 0; i <= 32; ++i)
    {
        IPv4::Addr mask = IPv4::Addr::netmask_from_prefix_len(i);
        const unsigned int pl = mask.prefix_len();
        ASSERT_EQ(pl, i);
        // std::cout << i << ' ' << pl << ' ' << mask << std::endl;
    }
}
 
void testbig() // exhaustive test of all 2^32 possible netmask values
{
    unsigned int mask = 0;
    while (true)
    {
        const int pl = prefix_len(mask);
        if (pl != -1)
            std::cout << pl << ' ' << IPv4::Addr::from_uint32(mask) << std::endl;
        if (++mask == 0)
            break;
    }
}