1 files changed, 111 insertions, 0 deletions
diff --git a/src/netgroup.cpp b/src/netgroup.cpp
new file mode 100644
index 0000000000..5f42d6c719
--- /dev/null
+++ b/src/netgroup.cpp
@@ -0,0 +1,111 @@
+// Copyright (c) 2021 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <netgroup.h>
+
+#include <hash.h>
+#include <util/asmap.h>
+
+uint256 NetGroupManager::GetAsmapChecksum() const
+{
+    if (!m_asmap.size()) return {};
+
+    return SerializeHash(m_asmap);
+}
+
+std::vector<unsigned char> NetGroupManager::GetGroup(const CNetAddr& address) const
+{
+    std::vector<unsigned char> vchRet;
+    // If non-empty asmap is supplied and the address is IPv4/IPv6,
+    // return ASN to be used for bucketing.
+    uint32_t asn = GetMappedAS(address);
+    if (asn != 0) { // Either asmap was empty, or address has non-asmappable net class (e.g. TOR).
+        vchRet.push_back(NET_IPV6); // IPv4 and IPv6 with same ASN should be in the same bucket
+        for (int i = 0; i < 4; i++) {
+            vchRet.push_back((asn >> (8 * i)) & 0xFF);
+        }
+        return vchRet;
+    }
+
+    vchRet.push_back(address.GetNetClass());
+    int nStartByte{0};
+    int nBits{0};
+
+    if (address.IsLocal()) {
+        // all local addresses belong to the same group
+    } else if (address.IsInternal()) {
+        // All internal-usage addresses get their own group.
+        // Skip over the INTERNAL_IN_IPV6_PREFIX returned by CAddress::GetAddrBytes().
+        nStartByte = INTERNAL_IN_IPV6_PREFIX.size();
+        nBits = ADDR_INTERNAL_SIZE * 8;
+    } else if (!address.IsRoutable()) {
+        // all other unroutable addresses belong to the same group
+    } else if (address.HasLinkedIPv4()) {
+        // IPv4 addresses (and mapped IPv4 addresses) use /16 groups
+        uint32_t ipv4 = address.GetLinkedIPv4();
+        vchRet.push_back((ipv4 >> 24) & 0xFF);
+        vchRet.push_back((ipv4 >> 16) & 0xFF);
+        return vchRet;
+    } else if (address.IsTor() || address.IsI2P()) {
+        nBits = 4;
+    } else if (address.IsCJDNS()) {
+        // Treat in the same way as Tor and I2P because the address in all of
+        // them is "random" bytes (derived from a public key). However in CJDNS
+        // the first byte is a constant 0xfc, so the random bytes come after it.
+        // Thus skip the constant 8 bits at the start.
+        nBits = 12;
+    } else if (address.IsHeNet()) {
+        // for he.net, use /36 groups
+        nBits = 36;
+    } else {
+        // for the rest of the IPv6 network, use /32 groups
+        nBits = 32;
+    }
+
+    // Push our address onto vchRet.
+    auto addr_bytes = address.GetAddrBytes();
+    const size_t num_bytes = nBits / 8;
+    vchRet.insert(vchRet.end(), addr_bytes.begin() + nStartByte, addr_bytes.begin() + nStartByte + num_bytes);
+    nBits %= 8;
+    // ...for the last byte, push nBits and for the rest of the byte push 1's
+    if (nBits > 0) {
+        assert(num_bytes < addr_bytes.size());
+        vchRet.push_back(addr_bytes[num_bytes] | ((1 << (8 - nBits)) - 1));
+    }
+
+    return vchRet;
+}
+
+uint32_t NetGroupManager::GetMappedAS(const CNetAddr& address) const
+{
+    uint32_t net_class = address.GetNetClass();
+    if (m_asmap.size() == 0 || (net_class != NET_IPV4 && net_class != NET_IPV6)) {
+        return 0; // Indicates not found, safe because AS0 is reserved per RFC7607.
+    }
+    std::vector<bool> ip_bits(128);
+    if (address.HasLinkedIPv4()) {
+        // For lookup, treat as if it was just an IPv4 address (IPV4_IN_IPV6_PREFIX + IPv4 bits)
+        for (int8_t byte_i = 0; byte_i < 12; ++byte_i) {
+            for (uint8_t bit_i = 0; bit_i < 8; ++bit_i) {
+                ip_bits[byte_i * 8 + bit_i] = (IPV4_IN_IPV6_PREFIX[byte_i] >> (7 - bit_i)) & 1;
+            }
+        }
+        uint32_t ipv4 = address.GetLinkedIPv4();
+        for (int i = 0; i < 32; ++i) {
+            ip_bits[96 + i] = (ipv4 >> (31 - i)) & 1;
+        }
+    } else {
+        // Use all 128 bits of the IPv6 address otherwise
+        assert(address.IsIPv6());
+        auto addr_bytes = address.GetAddrBytes();
+        for (int8_t byte_i = 0; byte_i < 16; ++byte_i) {
+            uint8_t cur_byte = addr_bytes[byte_i];
+            for (uint8_t bit_i = 0; bit_i < 8; ++bit_i) {
+                ip_bits[byte_i * 8 + bit_i] = (cur_byte >> (7 - bit_i)) & 1;
+            }
+        }
+    }
+    uint32_t mapped_as = Interpret(m_asmap, ip_bits);
+    return mapped_as;
+}