From 36649663402c712126e0f64a1d6fc0ba4faf1ad1 Mon Sep 17 00:00:00 2001 From: Adam Ierymenko Date: Thu, 17 Sep 2015 21:30:32 -0700 Subject: Generate local IPv6 addresses from network IDs and addresses. --- node/InetAddress.cpp | 26 ++++++++++++++++++++++++++ node/InetAddress.hpp | 44 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 70 insertions(+) (limited to 'node') diff --git a/node/InetAddress.cpp b/node/InetAddress.cpp index 1942c4cd..e542f0d4 100644 --- a/node/InetAddress.cpp +++ b/node/InetAddress.cpp @@ -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(&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 diff --git a/node/InetAddress.hpp b/node/InetAddress.hpp index e3537ce0..3c05d83b 100644 --- a/node/InetAddress.hpp +++ b/node/InetAddress.hpp @@ -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 -- cgit v1.2.3