bitcoin-bitcoin-core/src/test/fuzz/netbase_dns_lookup.cpp

// Copyright (c) 2021-2022 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 <netaddress.h>
#include <netbase.h>
#include <test/fuzz/FuzzedDataProvider.h>
#include <test/fuzz/fuzz.h>
#include <test/fuzz/util/net.h>

#include <cstdint>
#include <string>
#include <vector>

FUZZ_TARGET(netbase_dns_lookup)
{
    FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
    const std::string name = fuzzed_data_provider.ConsumeRandomLengthString(512);
    const unsigned int max_results = fuzzed_data_provider.ConsumeIntegral<unsigned int>();
    const bool allow_lookup = fuzzed_data_provider.ConsumeBool();
    const uint16_t default_port = fuzzed_data_provider.ConsumeIntegral<uint16_t>();

    auto fuzzed_dns_lookup_function = [&](const std::string&, bool) {
        std::vector<CNetAddr> resolved_addresses;
        LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 10000) {
            resolved_addresses.push_back(ConsumeNetAddr(fuzzed_data_provider));
        }
        return resolved_addresses;
    };

    {
        const std::vector<CNetAddr> resolved_addresses{LookupHost(name, max_results, allow_lookup, fuzzed_dns_lookup_function)};
        for (const CNetAddr& resolved_address : resolved_addresses) {
            assert(!resolved_address.IsInternal());
        }
        assert(resolved_addresses.size() <= max_results || max_results == 0);
    }
    {
        const std::optional<CNetAddr> resolved_address{LookupHost(name, allow_lookup, fuzzed_dns_lookup_function)};
        if (resolved_address.has_value()) {
            assert(!resolved_address.value().IsInternal());
        }
    }
    {
        const std::vector<CService> resolved_services{Lookup(name, default_port, allow_lookup, max_results, fuzzed_dns_lookup_function)};
        for (const CNetAddr& resolved_service : resolved_services) {
            assert(!resolved_service.IsInternal());
        }
        assert(resolved_services.size() <= max_results || max_results == 0);
    }
    {
        const std::optional<CService> resolved_service{Lookup(name, default_port, allow_lookup, fuzzed_dns_lookup_function)};
        if (resolved_service.has_value()) {
            assert(!resolved_service.value().IsInternal());
        }
    }
    {
        CService resolved_service = LookupNumeric(name, default_port, fuzzed_dns_lookup_function);
        assert(!resolved_service.IsInternal());
    }
    {
        (void)LookupSubNet(name);
    }
}