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       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         [ +  - ]:         929 : FUZZ_TARGET(asmap)
      23                 :             : {
      24                 :             :     // Encoding: [7 bits: asmap size] [1 bit: ipv6?] [3-130 bytes: asmap] [4 or 16 bytes: addr]
      25         [ +  + ]:         475 :     if (buffer.size() < 1 + 3 + 4) return;
      26         [ +  + ]:         473 :     int asmap_size = 3 + (buffer[0] & 127);
      27                 :         473 :     bool ipv6 = buffer[0] & 128;
      28         [ +  + ]:         473 :     const size_t addr_size = ipv6 ? ADDR_IPV6_SIZE : ADDR_IPV4_SIZE;
      29         [ +  + ]:         473 :     if (buffer.size() < size_t(1 + asmap_size + addr_size)) return;
      30         [ +  + ]:         725 :     std::vector<std::byte> asmap = ipv6 ? IPV6_PREFIX_ASMAP : IPV4_PREFIX_ASMAP;
      31   [ -  +  +  - ]:         468 :     std::ranges::copy(std::as_bytes(buffer.subspan(1, asmap_size)), std::back_inserter(asmap));
      32   [ -  +  +  -  :         468 :     if (!CheckStandardAsmap(asmap)) return;
                   +  + ]
      33                 :             : 
      34                 :         353 :     const uint8_t* addr_data = buffer.data() + 1 + asmap_size;
      35         [ +  - ]:         353 :     CNetAddr net_addr;
      36         [ +  + ]:         353 :     if (ipv6) {
      37         [ -  + ]:         195 :         assert(addr_size == ADDR_IPV6_SIZE);
      38         [ +  - ]:         195 :         net_addr.SetLegacyIPv6({addr_data, addr_size});
      39                 :             :     } else {
      40         [ -  + ]:         158 :         assert(addr_size == ADDR_IPV4_SIZE);
      41                 :         158 :         in_addr ipv4;
      42         [ +  - ]:         158 :         memcpy(&ipv4, addr_data, addr_size);
      43   [ +  -  +  - ]:         316 :         net_addr.SetIP(CNetAddr{ipv4});
      44                 :             :     }
      45         [ -  + ]:         353 :     auto netgroupman{NetGroupManager::WithEmbeddedAsmap(asmap)};
      46         [ +  - ]:         353 :     (void)netgroupman.GetMappedAS(net_addr);
      47                 :         468 : }