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Generate local IPv6 addresses from network IDs and addresses.

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This commit is contained in:
Adam Ierymenko 2015-09-17 21:30:32 -07:00
parent 610ab0750c
commit 3664966340
2 changed files with 70 additions and 0 deletions
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26
node/InetAddress.cpp
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@ -399,4 +399,30 @@ InetAddress InetAddress::makeIpv6LinkLocal(const MAC &mac)
return InetAddress(sin6);
}
InetAddress InetAddress::makeIpv6rfc4193(uint64_t nwid,uint64_t zeroTierAddress)
throw()
{
InetAddress r;
struct sockaddr_in6 *const sin6 = reinterpret_cast<struct sockaddr_in6 *>(&r);
sin6->sin6_family = AF_INET6;
sin6->sin6_addr.s6_addr[0] = 0xfd;
sin6->sin6_addr.s6_addr[1] = (uint8_t)(nwid >> 56);
sin6->sin6_addr.s6_addr[2] = (uint8_t)(nwid >> 48);
sin6->sin6_addr.s6_addr[3] = (uint8_t)(nwid >> 40);
sin6->sin6_addr.s6_addr[4] = (uint8_t)(nwid >> 32);
sin6->sin6_addr.s6_addr[5] = (uint8_t)(nwid >> 24);
sin6->sin6_addr.s6_addr[6] = (uint8_t)(nwid >> 16);
sin6->sin6_addr.s6_addr[7] = (uint8_t)(nwid >> 8);
sin6->sin6_addr.s6_addr[8] = (uint8_t)nwid;
sin6->sin6_addr.s6_addr[9] = 0x99;
sin6->sin6_addr.s6_addr[10] = 0x93;
sin6->sin6_addr.s6_addr[11] = (uint8_t)(zeroTierAddress >> 32);
sin6->sin6_addr.s6_addr[12] = (uint8_t)(zeroTierAddress >> 24);
sin6->sin6_addr.s6_addr[13] = (uint8_t)(zeroTierAddress >> 16);
sin6->sin6_addr.s6_addr[14] = (uint8_t)(zeroTierAddress >> 8);
sin6->sin6_addr.s6_addr[15] = (uint8_t)zeroTierAddress;
sin6->sin6_port = Utils::hton((uint16_t)88); // /88 includes 0xfd + network ID, discriminating by device ID below that
return r;
}
} // namespace ZeroTier

44
node/InetAddress.hpp
View File

@ -375,6 +375,50 @@ struct InetAddress : public sockaddr_storage
*/
static InetAddress makeIpv6LinkLocal(const MAC &mac)
throw();
/**
* Compute private IPv6 unicast address from network ID and ZeroTier address
*
* This generates a private unicast IPv6 address that is mostly compliant
* with the letter of RFC4193 and certainly compliant in spirit.
*
* RFC4193 specifies a format of:
*
* | 7 bits |1| 40 bits | 16 bits | 64 bits |
* | Prefix |L| Global ID | Subnet ID | Interface ID |
*
* The 'L' bit is set to 1, yielding an address beginning with 0xfd. Then
* the network ID is filled into the global ID, subnet ID, and first byte
* of the "interface ID" field. Since the first 40 bits of the network ID
* is the unique ZeroTier address of its controller, this makes a very
* good random global ID. Since network IDs have 24 more bits, we let it
* overflow into the interface ID.
*
* After that we pad with two bytes: 0x99, 0x93, namely the default ZeroTier
* port in hex.
*
* Finally we fill the remaining 40 bits of the interface ID field with
* the 40-bit unique ZeroTier device ID of the network member.
*
* This yields a valid RFC4193 address with a random global ID, a
* meaningful subnet ID, and a unique interface ID, all mappable back onto
* ZeroTier space.
*
* This in turn could allow us, on networks numbered this way, to emulate
* IPv6 NDP and eliminate all multicast. This could be beneficial for
* small devices and huge networks, e.g. IoT applications.
*
* The returned address is given an odd prefix length of /88, since within
* a given network only the last 40 bits (device ID) are variable. This
* is a bit unusual but as far as we know should not cause any problems with
* any non-braindead IPv6 stack.
*
* @param nwid 64-bit network ID
* @param zeroTierAddress 40-bit device address (in least significant 40 bits, highest 24 bits ignored)
* @return IPv6 private unicast address with /88 netmask
*/
static InetAddress makeIpv6rfc4193(uint64_t nwid,uint64_t zeroTierAddress)
throw();
};
} // namespace ZeroTier