Source: ../../libxorp/ipnet.hh
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// -*- c-basic-offset: 4; tab-width: 8; indent-tabs-mode: t -*-
// Copyright (c) 2001-2004 International Computer Science Institute
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software")
// to deal in the Software without restriction, subject to the conditions
// listed in the XORP LICENSE file. These conditions include: you must
// preserve this copyright notice, and you cannot mention the copyright
// holders in advertising related to the Software without their permission.
// The Software is provided WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED. This
// notice is a summary of the XORP LICENSE file; the license in that file is
// legally binding.
// $XORP: xorp/libxorp/ipnet.hh,v 1.11 2004/06/10 22:41:16 hodson Exp $
#ifndef __LIBXORP_IPNET_HH__
#define __LIBXORP_IPNET_HH__
#include "xorp.h"
#include "exceptions.hh"
#include "c_format.hh"
/**
* @short A template class for subnets
*
* A "subnet" is specified by a base "address" and a "prefix length".
*/
template <class A>
class IPNet {
public:
/**
* Default constructor taking no parameters.
*
* Default value has INADDR_ANY/0.
*/
IPNet() : _prefix_len(0) {}
/**
* Constructor from a given base address and a prefix length.
*
* @param a base address for the subnet.
* @param prefix_len length of subnet mask (e.g., class C nets would have
* prefix_len=24).
*/
IPNet(const A& a, uint32_t prefix_len) throw (InvalidNetmaskLength)
: _masked_addr(a), _prefix_len(prefix_len)
{
if (prefix_len > A::addr_bitlen())
xorp_throw(InvalidNetmaskLength, prefix_len);
_masked_addr = a.mask_by_prefix_len(prefix_len);
}
/**
* Constructor from a string.
*
* @param from_cstring C-style string with slash separated address
* and prefix length.
*/
IPNet(const char *from_cstring)
throw (InvalidString, InvalidNetmaskLength)
{
initialize_from_string(from_cstring);
}
/**
* Copy constructor
*
* @param n the subnet to copy from.
*/
IPNet(const IPNet& n) {
_masked_addr = n.masked_addr();
_prefix_len = n.prefix_len();
}
/**
* Assignment operator
*
* @param n the subnet to assign from.
* @return the subnet after the assignment.
*/
IPNet& operator=(const IPNet& n) {
_masked_addr = n.masked_addr();
_prefix_len = n.prefix_len();
return *this;
}
/**
* Equality Operator
*
* @param other the right-hand operand to compare against.
* @return true if the left-hand operand is numerically same as the
* right-hand operand.
*/
bool operator==(const IPNet& other) const {
return ((prefix_len() == other.prefix_len()) &&
(masked_addr() == other.masked_addr()));
}
/**
* Less-Than Operator
*
* Less-than comparison for subnets (see body for description).
*
* @param other the right-hand side of the comparison.
* @return true if the left-hand side is "smaller" than the right-hand
* side according to the chosen order.
*/
inline bool operator<(const IPNet& other) const;
/**
* Decrement Operator
*
* The numerical value of the prefix address is decrement by one.
* Example: decrementing 128.2.0.0/16 results in 128.1.0.0/16.
*
* @return a reference to this subnet after the decrement
*/
IPNet& operator--();
/**
* Increment Operator
*
* The numerical value of the prefix address is incremented by one.
* Example: incrementing 128.2.0.0/16 results in 128.3.0.0/16.
*
* @return a reference to this subnet after the increment
*/
IPNet& operator++();
/**
* Convert this address from binary form to presentation format.
*
* @return C++ string with the human-readable ASCII representation
* of the address.
*/
inline string str() const {
return _masked_addr.str() + c_format("/%u", (uint32_t)_prefix_len);
}
/**
* Test if the object contains a real (non-default) value.
*
* @return true if the object stores a real (non-default) value.
*/
bool is_valid() const { return _prefix_len != 0; }
/**
* Test if subnets overlap.
*
* @param other the subnet to compare against.
* @return true if there is some overlap between the two subnets.
*/
inline bool is_overlap(const IPNet& other) const;
/**
* Test if a subnet contains (or is equal to) another subnet.
*
* in LaTeX, x.contains(y) would be $x \superseteq y$
*
* @param other the subnet to test against.
* @return true if this subnet contains or is equal to @ref other.
*/
inline bool contains(const IPNet& other) const;
/**
* Test if an address is within a subnet.
*
* @param addr the address to test against.
* @return true if @ref addr is within this subnet.
*/
inline bool contains(const A& addr) const {
return addr.mask_by_prefix_len(_prefix_len) == _masked_addr;
}
/**
* Determine the number of the most significant bits overlapping with
* another subnet.
*
* @param other the subnet to test against.
* @return the number of bits overlapping between @ref other and
* this subnet.
*/
inline uint32_t overlap(const IPNet& other) const;
/**
* Get the address family.
*
* @return the address family of this address.
*/
static const int af() { return A::af(); }
/**
* Get the base address.
*
* @return the base address for this subnet.
*/
inline const A& masked_addr() const { return _masked_addr; }
/**
* Get the prefix length.
*
* @return the prefix length for this subnet.
*/
inline uint32_t prefix_len() const { return _prefix_len; }
/**
* Get the network mask.
*
* @return the netmask associated with this subnet.
*/
inline A netmask() const { return _masked_addr.make_prefix(_prefix_len); }
/**
* Return the subnet containing all multicast addresses.
*
* Note that this is a static function and can be used without
* a particular object. Example:
* IPv4Net my_prefix = IPv4Net::ip_multicast_base_prefix(); OK
* IPv4Net my_prefix = ipv4net.ip_multicast_base_prefix(); OK
*
* @return the subnet containing multicast addresses.
*/
static const IPNet<A> ip_multicast_base_prefix() {
return IPNet(A::MULTICAST_BASE(),
A::ip_multicast_base_address_mask_len());
}
/**
* Test if this subnet is within the multicast address range.
*
* @return true if this subnet is within the multicast address range.
*/
bool is_multicast() const {
return (ip_multicast_base_prefix().contains(*this));
}
/**
* Get the highest address within this subnet.
*
* @return the highest address within this subnet.
*/
inline A top_addr() const { return _masked_addr | ~netmask(); }
/**
* Get the smallest subnet containing both subnets.
*
* @return the smallest subnet containing both subnets passed
* as arguments.
*/
static IPNet<A> common_subnet(const IPNet<A> x, const IPNet<A> y) {
return IPNet<A>(x.masked_addr(), x.overlap(y));
}
protected:
inline void initialize_from_string(const char *s)
throw (InvalidString, InvalidNetmaskLength);
A _masked_addr;
uint32_t _prefix_len;
};
/* ------------------------------------------------------------------------- */
/* Deferred method definitions */
template <class A> bool
IPNet<A>::operator<(const IPNet& other) const
{
#if 1
/*
* say x = A/B and y = C/D, then
*
* x < y :
*
* if x.contains(y) // equal is fine
* return false
* else if y.strictly_contains(x) // equal already taken care of
* return true
* else
* return A < C
*
* |---x---|
* x=y |---y---|
* x>y |-y-|
* x<y |------y-------|
* x<y |-----y---------|
* x<y |--y-|
*/
if (this->contains(other))
return false;
else if (other.contains(*this))
return true;
else
return this->masked_addr() < other.masked_addr();
#else // old code
const A& maddr_him = other.masked_addr();
uint32_t his_prefix_len = other.prefix_len();
//the ordering is important because we want the longest match to
//be first. For example, we want the following:
// 128.16.0.0/24 < 128.16.64.0/24 < 128.16.0.0/16 < 128.17.0.0/24
if (_prefix_len == his_prefix_len) return _masked_addr < maddr_him;
// we need to check the case when one subnet is a subset of
// the other
if (_prefix_len < his_prefix_len) {
A test_addr(maddr_him.mask_by_prefix_len(_prefix_len));
if (_masked_addr == test_addr) {
//his subnet is a subset of mine, so he goes first.
return (false);
}
} else if (_prefix_len > his_prefix_len) {
A test_addr(_masked_addr.mask_by_prefix_len(his_prefix_len));
if (maddr_him == test_addr) {
//my subnet is a subset of his, so I go first.
return (true);
}
}
//the subnets don't overlap (or are identical), so just order by address
if (_masked_addr < maddr_him) {
return (true);
}
return (false);
#endif
}
template <class A> bool
IPNet<A>::is_overlap(const IPNet<A>& other) const
{
if (prefix_len() > other.prefix_len()) {
// I have smaller prefix size
IPNet other_masked(masked_addr(), other.prefix_len());
return (other_masked.masked_addr() == other.masked_addr());
}
if (prefix_len() < other.prefix_len()) {
// I have bigger prefix size
IPNet other_masked(other.masked_addr(), prefix_len());
return (other_masked.masked_addr() == masked_addr());
}
// Same prefix size
return (other.masked_addr() == masked_addr());
}
template <class A> bool
IPNet<A>::contains(const IPNet<A>& other) const
{
if (prefix_len() > other.prefix_len()) {
// I have smaller prefix size, hence I don't contain other.
return (false);
}
if (prefix_len() < other.prefix_len()) {
// I have bigger prefix size
IPNet other_masked(other.masked_addr(), prefix_len());
return (other_masked.masked_addr() == masked_addr());
}
// Same prefix size
return (other.masked_addr() == masked_addr());
}
template <class A> void
IPNet<A>::initialize_from_string(const char *cp)
throw (InvalidString, InvalidNetmaskLength)
{
char *slash = strrchr(cp, '/');
if (slash == 0)
xorp_throw(InvalidString, "Missing slash");
if (*(slash + 1) == 0)
xorp_throw(InvalidString, "Missing prefix length");
_prefix_len = atoi(slash + 1);
string addr = string(cp, slash - cp);
_masked_addr = A(addr.c_str()).mask_by_prefix_len(_prefix_len);
}
template <class A> IPNet<A>&
IPNet<A>::operator--()
{
_masked_addr = _masked_addr >> (_masked_addr.addr_bitlen() - _prefix_len);
--_masked_addr;
_masked_addr = _masked_addr << (_masked_addr.addr_bitlen() - _prefix_len);
return (*this);
}
template <class A> IPNet<A>&
IPNet<A>::operator++()
{
_masked_addr = _masked_addr >> (_masked_addr.addr_bitlen() - _prefix_len);
++_masked_addr;
_masked_addr = _masked_addr << (_masked_addr.addr_bitlen() - _prefix_len);
return (*this);
}
template <class A>
inline uint32_t
IPNet<A>::overlap(const IPNet<A>& other) const
{
A addr = masked_addr() ^ other.masked_addr();
uint32_t p = (prefix_len() < other.prefix_len()) ?
prefix_len() : other.prefix_len();
uint32_t i = 0;
for (A o(A::ALL_ONES(_masked_addr.af())); i <= p; o = o >> 1, i++) {
if (o < addr)
return i - 1;
}
return i - 1;
}
/**
* Determine the number of the most significant bits overlapping
* between two subnets.
*
* @param a1 the first subnet.
* @param a2 the subnet.
* @return the number of bits overlapping between @ref a1 and @ref a2.
*/
template <class A> uint32_t
overlap(const IPNet<A>& a1, const IPNet<A>& a2)
{
return a1.overlap(a2);
}
#endif // __LIBXORP_IPNET_HH__
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