IPv6Address.cc

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//
// Copyright (C) 2005 Wei Yang, Ng
// Copyright (C) 2005 Andras Varga
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this program; if not, see <http://www.gnu.org/licenses/>.
//

#include <iostream>
#include <sstream>
#include "IPv6Address.h"
#include "InterfaceToken.h"

const uint32 LINK_LOCAL_PREFIX = 0xFE800000;
const uint32 SITE_LOCAL_PREFIX = 0xFEC00000;
const uint32 MULTICAST_PREFIX = 0xFF000000;

//Link and Site local masks should only preserve 10 bits as prefix length is 10.
const uint32 LINK_LOCAL_MASK = 0xFFC00000;
const uint32 SITE_LOCAL_MASK = 0xFFC00000;
const uint32 MULTICAST_MASK = 0xFF000000;

// RFC 3513: IPv6 Addressing Architecture
// Section 2.7.1: Pre-defined Multicast Addresses
const IPv6Address IPv6Address::UNSPECIFIED_ADDRESS("::0");
const IPv6Address IPv6Address::LOOPBACK_ADDRESS("::1");
const IPv6Address IPv6Address::ALL_NODES_1("FF01::1");
const IPv6Address IPv6Address::ALL_NODES_2("FF02::1");
const IPv6Address IPv6Address::ALL_ROUTERS_1("FF01::2");
const IPv6Address IPv6Address::ALL_ROUTERS_2("FF02::2");
const IPv6Address IPv6Address::ALL_ROUTERS_5("FF05::2");
const IPv6Address IPv6Address::SOLICITED_NODE_PREFIX("FF02:0:0:0:0:1:FF00:0");
const IPv6Address IPv6Address::LINKLOCAL_PREFIX("FE80::");


// returns numOctals; advances s just over the last hex digit converted
// FIXME "octal" appears to be a bad name
static int parseOctals(const char *&s, int *octals)
{
    int k = 0;
    while (1)
    {
        char *e;
        octals[k] = strtoul(s,&e,16);
        if (s==e) { // no hex digit converted
            if (k!=0) s--;  // "unskip" preceding ':'
            return k;
        }
        // if negative or too big, return (s will point to beginning of large number)
        if (octals[k]<0 || octals[k]>0xffff)
            return k;
        k++;  // octals[k] successfully stored
        s = e;  // skip converted hex number
        if (*s!=':' || k==8)
            return k;
        s++;  // skip ':'
    }
}

bool IPv6Address::doTryParse(const char *&addr)
{
    if (!strcmp(addr,"<unspec>"))
    {
        addr += 8;
        d[0] = d[1] = d[2] = d[3] = 0;
        return true;
    }

    // parse and store 16-bit units
    int octals[8];
    int numOctals = parseOctals(addr, octals);

    // if address string contains "::", parse and store second half too
    if (*addr==':' && *(addr+1)==':')
    {
        addr += 2;
        int suffixOctals[8];
        int numSuffixOctals = parseOctals(addr, suffixOctals);

        // merge suffixOctals[] into octals[]
        if (numOctals+numSuffixOctals>8)
            return false; // too many
        for (int i=numOctals; i<8; i++) {
            int j = i-8+numSuffixOctals;
            octals[i] = j<0 ? 0 : suffixOctals[j];
        }
        numOctals = 8;
    }

    if (numOctals!=8)
        return false; // too few

    // copy octets to d[]
    for (unsigned int i=0; i<4; i++)
        d[i] = (octals[i*2]<<16) + octals[2*i + 1];

    return true;
}

bool IPv6Address::tryParse(const char *addr)
{
    if (!addr)
        return false;
    if (!doTryParse(addr))
        return false;
    if (*addr!=0)
        return false; // illegal trailing character
    return true;
}

bool IPv6Address::tryParseAddrWithPrefix(const char *addr, int& prefixLen)
{
    if (!addr)
        return false;
    if (!doTryParse(addr))
        return false;
    if (*addr!='/')
        return false; // no '/' after address
    addr++;

    // parse prefix
    char *e;
    prefixLen = strtoul(addr,&e,10);
    if (addr==e)
        return false; // no number after '/'
    if (*e!=0)
        return false; // garbage after number
    if (prefixLen<0 || prefixLen>128)
        return false; // wrong len value
    return true;
}

void IPv6Address::set(const char *addr)
{
    if (!tryParse(addr))
        throw cRuntimeError("IPv6Address: cannot interpret address string `%s'", addr);
}

// find longest sequence of zeros in address (at least with len=2)
static void findGap(int *octals, int& start, int& end)
{
    start = end = 0;
    int beg = -1;
    for (int i=0; i<8; i++)
    {
        if (beg==-1 && octals[i]==0)
        {
            // begin counting
            beg = i;
        }
        else if (beg!=-1 && octals[i]!=0)
        {
            // end counting
            if (i-beg>=2 && i-beg>end-start) {
                start = beg; end = i;
            }
            beg = -1;
        }
    }

    // check last zero-seq
    if (beg!=-1 && beg<=6 && 8-beg>end-start) {
        start = beg; end = 8;
    }
}

std::string IPv6Address::str() const
{
    if (isUnspecified())
        return std::string("<unspec>");

    // convert to 16-bit octals
    int octals[8] = {
        (d[0]>>16), (d[0]&0xffff), (d[1]>>16), (d[1]&0xffff),
        (d[2]>>16), (d[2]&0xffff), (d[3]>>16), (d[3]&0xffff)
    };

    // find longest sequence of zeros in octals[]
    int start, end;
    findGap(octals, start, end);
    if (start==0 && end==8)
        return "::0";  // the unspecified address is a special case

    // print octals, replacing gap with "::"
    std::stringstream os;
    os << std::hex;
    for (int i=0; i<start; i++)
        os << (i==0?"":":") << octals[i];
    if (start!=end)
        os << "::";
    for (int j=end; j<8; j++)
        os << (j==end?"":":") << octals[j];
    return os.str();
}

IPv6Address::Scope IPv6Address::getScope() const
{
    //Mask the given IPv6 address with the different mask types
    //to get only the IPv6 address scope. Compare the masked
    //address with the different prefixes.

    if ((d[0] & LINK_LOCAL_MASK) == LINK_LOCAL_PREFIX )
    {
        return LINK;
    }
    else if ((d[0] & SITE_LOCAL_MASK) == SITE_LOCAL_PREFIX )
    {
        return SITE;
    }
    else if ((d[0] & MULTICAST_MASK) == MULTICAST_PREFIX )
    {
        return MULTICAST;
    }
    else if (d[0] == 0x00000000 && d[1] == 0x00000000 && d[2] == 0x00000000)
    {
        if (d[3] == 0x00000000)
        {
            return UNSPECIFIED;
        }
        else if (d[3] == 0x00000001)
        {
            return LOOPBACK;
        }
        else
        {
            return GLOBAL; // actually an "IPv4-compatible IPv6 address"
        }
    }
    else
    {
        return GLOBAL;
    }
}

const char *IPv6Address::scopeName(Scope scope)
{
    switch (scope)
    {
        case UNSPECIFIED:        return "unspec";
        case LOOPBACK:           return "loopback";
        case MULTICAST:          return "mcast";
        case LINK:               return "link";
        case SITE:               return "site";
        case GLOBAL:             return "global";
        default:                 return "???";
    }
}

void IPv6Address::constructMask(int prefixLength, uint32 *mask)
{
    ASSERT(prefixLength>=0 && prefixLength<=128 && mask!=NULL);

    // create a mask based on the prefix length.
    if (prefixLength==0)
    {
        mask[0] = mask[1] = mask[2] = mask[3] = 0x00000000;
    }
    else if (prefixLength<=32)
    {
        int num_of_shifts = 32 - prefixLength;
        mask[0] = 0xFFFFFFFFU << num_of_shifts;
        mask[1] = 0x00000000;
        mask[2] = 0x00000000;
        mask[3] = 0x00000000;
    }
    else if (prefixLength<=64)
    {
        int num_of_shifts = 64 - prefixLength;
        mask[0] = 0xFFFFFFFFU;
        mask[1] = 0xFFFFFFFFU << num_of_shifts;
        mask[2] = 0x00000000;
        mask[3] = 0x00000000;
    }
    else if (prefixLength<=96)
    {
        int num_of_shifts = 96 - prefixLength;
        mask[0] = 0xFFFFFFFFU;
        mask[1] = 0xFFFFFFFFU;
        mask[2] = 0xFFFFFFFFU << num_of_shifts;
        mask[3] = 0x00000000;
    }
    else
    {
        int num_of_shifts = 128 - prefixLength;
        mask[0] = 0xFFFFFFFFU;
        mask[1] = 0xFFFFFFFFU;
        mask[2] = 0xFFFFFFFFU;
        mask[3] = 0xFFFFFFFFU << num_of_shifts;
    }
}

IPv6Address IPv6Address::getPrefix(int prefixLength) const
{
    // First we construct a mask.
    uint32 mask[4];
    constructMask(prefixLength, mask);

    // Now we mask each IPv6 address segment and create a new IPv6 Address!
    return IPv6Address(d[0]&mask[0],d[1]&mask[1],d[2]&mask[2],d[3]&mask[3] );
}

IPv6Address IPv6Address::getSuffix(int prefixLength) const
{
    // First we construct a mask.
    uint32 mask[4];
    constructMask(prefixLength, mask);

    // Now we mask each IPv6 address segment, inverse it
    // and create a new IPv6 Address!
    return IPv6Address(d[0]&~mask[0],d[1]&~mask[1],d[2]&~mask[2],d[3]&~mask[3] );
}

const IPv6Address& IPv6Address::setPrefix(const IPv6Address& fromAddr, int prefixLength)
{
    // first we construct a mask.
    uint32 mask[4];
    constructMask(prefixLength, mask);

    // combine the addresses
    d[0] = (d[0]&~mask[0]) | (fromAddr.d[0]&mask[0]);
    d[1] = (d[1]&~mask[1]) | (fromAddr.d[1]&mask[1]);
    d[2] = (d[2]&~mask[2]) | (fromAddr.d[2]&mask[2]);
    d[3] = (d[3]&~mask[3]) | (fromAddr.d[3]&mask[3]);
    return *this;
}


const IPv6Address& IPv6Address::setSuffix(const IPv6Address& fromAddr, int prefixLength)
{
    // first we construct a mask.
    uint32 mask[4];
    constructMask(prefixLength, mask);

    // combine the addresses
    d[0] = (d[0]&mask[0]) | (fromAddr.d[0]&~mask[0]);
    d[1] = (d[1]&mask[1]) | (fromAddr.d[1]&~mask[1]);
    d[2] = (d[2]&mask[2]) | (fromAddr.d[2]&~mask[2]);
    d[3] = (d[3]&mask[3]) | (fromAddr.d[3]&~mask[3]);
    return *this;
}

IPv6Address IPv6Address::formLinkLocalAddress(const InterfaceToken& ident)
{
    IPv6Address suffix(0, 0, ident.normal(), ident.low());
    IPv6Address linkLocalAddr = IPv6Address::LINKLOCAL_PREFIX;
    linkLocalAddr.setSuffix(suffix, 128-ident.length());
    return linkLocalAddr;
}

bool IPv6Address::matches(const IPv6Address& prefix, int prefixLength) const
{
    // first we construct a mask.
    uint32 mask[4];
    constructMask(prefixLength, mask);

    // xor the bits of the 2 addresses, and the result should be zero wherever
    // the mask has 1 bits
    return (((d[0]^prefix.d[0])&mask[0]) | ((d[1]^prefix.d[1])&mask[1]) |
            ((d[2]^prefix.d[2])&mask[2]) | ((d[3]^prefix.d[3])&mask[3]))==0;
}

int IPv6Address::getMulticastScope() const
{
    if ((d[0] & MULTICAST_MASK)!=MULTICAST_PREFIX)
        throw cRuntimeError("IPv6Address::getMulticastScope(): %s is not a multicast address", str().c_str());
    return (d[0] >> 16) & 0x0F;
}