1  // Copyright (c) 2020-present The Bitcoin Core developers
 2  // Distributed under the MIT software license, see the accompanying
 3  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 4  
 5  #include <netaddress.h>
 6  #include <netgroup.h>
 7  #include <test/fuzz/fuzz.h>
 8  #include <util/asmap.h>
 9  #include <util/strencodings.h>
10  
11  #include <cstdint>
12  #include <vector>
13  
14  using namespace util::hex_literals;
15  
16  //! asmap code that consumes nothing
17  static const std::vector<std::byte> IPV6_PREFIX_ASMAP = {};
18  
19  //! asmap code that consumes the 96 prefix bits of ::ffff:0/96 (IPv4-in-IPv6 map)
20  static const auto IPV4_PREFIX_ASMAP = "fb03ec0fb03fc0fe00fb03ec0fb03fc0fe00fb03ec0fb0fffffeff"_hex_v;
21  
22  FUZZ_TARGET(asmap)
23  {
24      // Encoding: [7 bits: asmap size] [1 bit: ipv6?] [3-130 bytes: asmap] [4 or 16 bytes: addr]
25      if (buffer.size() < 1 + 3 + 4) return;
26      int asmap_size = 3 + (buffer[0] & 127);
27      bool ipv6 = buffer[0] & 128;
28      const size_t addr_size = ipv6 ? ADDR_IPV6_SIZE : ADDR_IPV4_SIZE;
29      if (buffer.size() < size_t(1 + asmap_size + addr_size)) return;
30      std::vector<std::byte> asmap = ipv6 ? IPV6_PREFIX_ASMAP : IPV4_PREFIX_ASMAP;
31      std::ranges::copy(std::as_bytes(buffer.subspan(1, asmap_size)), std::back_inserter(asmap));
32      if (!CheckStandardAsmap(asmap)) return;
33  
34      const uint8_t* addr_data = buffer.data() + 1 + asmap_size;
35      CNetAddr net_addr;
36      if (ipv6) {
37          assert(addr_size == ADDR_IPV6_SIZE);
38          net_addr.SetLegacyIPv6({addr_data, addr_size});
39      } else {
40          assert(addr_size == ADDR_IPV4_SIZE);
41          in_addr ipv4;
42          memcpy(&ipv4, addr_data, addr_size);
43          net_addr.SetIP(CNetAddr{ipv4});
44      }
45      auto netgroupman{NetGroupManager::WithEmbeddedAsmap(asmap)};
46      (void)netgroupman.GetMappedAS(net_addr);
47  }