From 36649663402c712126e0f64a1d6fc0ba4faf1ad1 Mon Sep 17 00:00:00 2001
From: Adam Ierymenko <adam.ierymenko@gmail.com>
Date: Thu, 17 Sep 2015 21:30:32 -0700
Subject: [PATCH] Generate local IPv6 addresses from network IDs and addresses.
---
node/InetAddress.cpp | 26 ++++++++++++++++++++++++++
node/InetAddress.hpp | 44 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 70 insertions(+)
diff --git a/node/InetAddress.cpp b/node/InetAddress.cpp
index 1942c4cd4..e542f0d4e 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<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
diff --git a/node/InetAddress.hpp b/node/InetAddress.hpp
index e3537ce0c..3c05d83b5 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