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

Code before:
            SleepOnFailure();
            continue;
        }

        CreateNodeFromAcceptedSocket(std::move(conn.sock), NetPermissionFlags::None,
                                     CAddress{conn.me, NODE_NONE}, CAddress{conn.peer, NODE_NONE});

        err_wait = err_wait_begin;
    }
}

bool CConnman::BindListenPort(const CService& addrBind, bilingual_str& strError, NetPermissionFlags permissions)
{
    int nOne = 1;

    // Create socket for listening for incoming connections
    struct sockaddr_storage sockaddr;
    socklen_t len = sizeof(sockaddr);
    if (!addrBind.GetSockAddr((struct sockaddr*)&sockaddr, &len))
    {
        strError = strprintf(Untranslated("Bind address family for %s not supported"), addrBind.ToStringAddrPort());
        LogPrintLevel(BCLog::NET, BCLog::Level::Error, "%s\n", strError.original);
        return false;
    }

    std::unique_ptr<Sock> sock = CreateSock(addrBind.GetSAFamily());
    if (!sock) {
        strError = strprintf(Untranslated("Couldn't open socket for incoming connections (socket returned error %s)"), NetworkErrorString(WSAGetLastError()));
        LogPrintLevel(BCLog::NET, BCLog::Level::Error, "%s\n", strError.original);
        return false;
    }

    // Allow binding if the port is still in TIME_WAIT state after
    // the program was closed and restarted.
    if (sock->SetSockOpt(SOL_SOCKET, SO_REUSEADDR, (sockopt_arg_type)&nOne, sizeof(int)) == SOCKET_ERROR) {
        strError = strprintf(Untranslated("Error setting SO_REUSEADDR on socket: %s, continuing anyway"), NetworkErrorString(WSAGetLastError()));
        LogPrintf("%s\n", strError.original);
    }

    // some systems don't have IPV6_V6ONLY but are always v6only; others do have the option
    // and enable it by default or not. Try to enable it, if possible.
    if (addrBind.IsIPv6()) {
#ifdef IPV6_V6ONLY
        if (sock->SetSockOpt(IPPROTO_IPV6, IPV6_V6ONLY, (sockopt_arg_type)&nOne, sizeof(int)) == SOCKET_ERROR) {
            strError = strprintf(Untranslated("Error setting IPV6_V6ONLY on socket: %s, continuing anyway"), NetworkErrorString(WSAGetLastError()));
            LogPrintf("%s\n", strError.original);
        }
#endif
#ifdef WIN32
        int nProtLevel = PROTECTION_LEVEL_UNRESTRICTED;
        if (sock->SetSockOpt(IPPROTO_IPV6, IPV6_PROTECTION_LEVEL, (const char*)&nProtLevel, sizeof(int)) == SOCKET_ERROR) {

Review comment (suggestion):
I'm assuming changing `GetSAFamily()`'s return type was avoided to keep the PR scoped (and since the change doesn't seem necessary).

Since `GetSAFamily()` returns `sa_family_t`, looks like this is a simple promotion from an `unsigned short` (`sa_family_t`) to `int`.  This seems fine (it aligns with the typical way `socket()` args are typically used).  

Code after:
            SleepOnFailure();
            continue;
        }

        CreateNodeFromAcceptedSocket(std::move(conn.sock), NetPermissionFlags::None,
                                     CAddress{conn.me, NODE_NONE}, CAddress{conn.peer, NODE_NONE});

        err_wait = err_wait_begin;
    }
}

bool CConnman::BindListenPort(const CService& addrBind, bilingual_str& strError, NetPermissionFlags permissions)
{
    int nOne = 1;

    // Create socket for listening for incoming connections
    struct sockaddr_storage sockaddr;
    socklen_t len = sizeof(sockaddr);
    if (!addrBind.GetSockAddr((struct sockaddr*)&sockaddr, &len))
    {
        strError = strprintf(Untranslated("Bind address family for %s not supported"), addrBind.ToStringAddrPort());
        LogPrintLevel(BCLog::NET, BCLog::Level::Error, "%s\n", strError.original);
        return false;
    }

    std::unique_ptr<Sock> sock = CreateSock(addrBind.GetSAFamily(), SOCK_STREAM, IPPROTO_TCP);
    if (!sock) {
        strError = strprintf(Untranslated("Couldn't open socket for incoming connections (socket returned error %s)"), NetworkErrorString(WSAGetLastError()));
        LogPrintLevel(BCLog::NET, BCLog::Level::Error, "%s\n", strError.original);
        return false;
    }

    // Allow binding if the port is still in TIME_WAIT state after
    // the program was closed and restarted.
    if (sock->SetSockOpt(SOL_SOCKET, SO_REUSEADDR, (sockopt_arg_type)&nOne, sizeof(int)) == SOCKET_ERROR) {
        strError = strprintf(Untranslated("Error setting SO_REUSEADDR on socket: %s, continuing anyway"), NetworkErrorString(WSAGetLastError()));
        LogPrintf("%s\n", strError.original);
    }

    // some systems don't have IPV6_V6ONLY but are always v6only; others do have the option
    // and enable it by default or not. Try to enable it, if possible.
    if (addrBind.IsIPv6()) {
#ifdef IPV6_V6ONLY
        if (sock->SetSockOpt(IPPROTO_IPV6, IPV6_V6ONLY, (sockopt_arg_type)&nOne, sizeof(int)) == SOCKET_ERROR) {
            strError = strprintf(Untranslated("Error setting IPV6_V6ONLY on socket: %s, continuing anyway"), NetworkErrorString(WSAGetLastError()));
            LogPrintf("%s\n", strError.original);
        }
#endif
#ifdef WIN32
        int nProtLevel = PROTECTION_LEVEL_UNRESTRICTED;
        if (sock->SetSockOpt(IPPROTO_IPV6, IPV6_PROTECTION_LEVEL, (const char*)&nProtLevel, sizeof(int)) == SOCKET_ERROR) {