Repository: bitcoin/bitcoin
File: src/netbase.cpp (C++)

Code before:
    // getaddrinfo to only decode numerical network addresses and suppress
    // hostname lookups.
    ai_hint.ai_flags = allow_lookup ? AI_ADDRCONFIG : AI_NUMERICHOST;

    addrinfo* ai_res{nullptr};
    const int n_err{getaddrinfo(name.c_str(), nullptr, &ai_hint, &ai_res)};
    if (n_err != 0) {
        return {};
    }

    // Traverse the linked list starting with ai_trav.
    addrinfo* ai_trav{ai_res};
    std::vector<CNetAddr> resolved_addresses;
    while (ai_trav != nullptr) {
        if (ai_trav->ai_family == AF_INET) {
            assert(ai_trav->ai_addrlen >= sizeof(sockaddr_in));
            resolved_addresses.emplace_back(reinterpret_cast<sockaddr_in*>(ai_trav->ai_addr)->sin_addr);
        }
        if (ai_trav->ai_family == AF_INET6) {
            assert(ai_trav->ai_addrlen >= sizeof(sockaddr_in6));
            const sockaddr_in6* s6{reinterpret_cast<sockaddr_in6*>(ai_trav->ai_addr)};
            resolved_addresses.emplace_back(s6->sin6_addr, s6->sin6_scope_id);
        }
        ai_trav = ai_trav->ai_next;
    }
    freeaddrinfo(ai_res);

    return resolved_addresses;
}

DNSLookupFn g_dns_lookup{WrappedGetAddrInfo};

enum Network ParseNetwork(const std::string& net_in) {
    std::string net = ToLower(net_in);
    if (net == "ipv4") return NET_IPV4;
    if (net == "ipv6") return NET_IPV6;
    if (net == "onion") return NET_ONION;
    if (net == "tor") {
        LogPrintf("Warning: net name 'tor' is deprecated and will be removed in the future. You should use 'onion' instead.\n");
        return NET_ONION;
    }
    if (net == "i2p") {
        return NET_I2P;
    }
    if (net == "cjdns") {
        return NET_CJDNS;
    }
    return NET_UNROUTABLE;
}

std::string GetNetworkName(enum Network net)

Review comment (suggestion):
nit, feel free to ignore if you find the current one more readable, but this is equivalent to:

```suggestion
            if (!only_add_local_addr || addr.IsLocal()) {
```

Code after:
    // hostname lookups.
    ai_hint.ai_flags = allow_lookup ? AI_ADDRCONFIG : AI_NUMERICHOST;

    addrinfo* ai_res{nullptr};
    const int n_err{getaddrinfo(name.c_str(), nullptr, &ai_hint, &ai_res)};
    if (n_err != 0) {
        if ((ai_hint.ai_flags & AI_ADDRCONFIG) == AI_ADDRCONFIG) {
            // AI_ADDRCONFIG on some systems may exclude loopback-only addresses
            // If first lookup failed we perform a second lookup without AI_ADDRCONFIG
            ai_hint.ai_flags = (ai_hint.ai_flags & ~AI_ADDRCONFIG);
            const int n_err_retry{getaddrinfo(name.c_str(), nullptr, &ai_hint, &ai_res)};
            if (n_err_retry != 0) {
                return {};
            }
        } else {
            return {};
        }
    }

    // Traverse the linked list starting with ai_trav.
    addrinfo* ai_trav{ai_res};
    std::vector<CNetAddr> resolved_addresses;
    while (ai_trav != nullptr) {
        if (ai_trav->ai_family == AF_INET) {
            assert(ai_trav->ai_addrlen >= sizeof(sockaddr_in));
            resolved_addresses.emplace_back(reinterpret_cast<sockaddr_in*>(ai_trav->ai_addr)->sin_addr);
        }
        if (ai_trav->ai_family == AF_INET6) {
            assert(ai_trav->ai_addrlen >= sizeof(sockaddr_in6));
            const sockaddr_in6* s6{reinterpret_cast<sockaddr_in6*>(ai_trav->ai_addr)};
            resolved_addresses.emplace_back(s6->sin6_addr, s6->sin6_scope_id);
        }
        ai_trav = ai_trav->ai_next;
    }
    freeaddrinfo(ai_res);

    return resolved_addresses;
}

DNSLookupFn g_dns_lookup{WrappedGetAddrInfo};

enum Network ParseNetwork(const std::string& net_in) {
    std::string net = ToLower(net_in);
    if (net == "ipv4") return NET_IPV4;
    if (net == "ipv6") return NET_IPV6;
    if (net == "onion") return NET_ONION;
    if (net == "tor") {
        LogPrintf("Warning: net name 'tor' is deprecated and will be removed in the future. You should use 'onion' instead.\n");
        return NET_ONION;
    }
    if (net == "i2p") {