include_guard "network"

include "pppoe.ncdi"
include "dhcp_server.ncdi"
include "unbound.ncdi"
include "network_control_server.ncdi"
include "port_forwarding.ncdi"

template network_main {
    log("notice", "NCD starting");
    log_r("notice", "NCD stopped");

    # Load ipv6 module so we can disable ipv6.
    runonce({"/sbin/modprobe", "ipv6"});

    # Set some sysctl's.
    runonce({"/sbin/sysctl", "net.ipv4.ip_forward=1"});
    runonce({"/sbin/sysctl", "net.ipv6.conf.all.disable_ipv6=1"});

    # Setup iptables INPUT chain.
    net.iptables.policy("filter", "INPUT", "ACCEPT", "ACCEPT");
    net.iptables.append("filter", "INPUT", "-i", "lo", "-j", "ACCEPT");
    net.iptables.append("filter", "INPUT", "-m", "conntrack", "--ctstate", "ESTABLISHED", "-j", "ACCEPT");

    # Setup iptables OUTPUT chain.
    net.iptables.policy("filter", "OUTPUT", "ACCEPT", "ACCEPT");

    # Setup iptables FORWARD chain.
    net.iptables.policy("filter", "FORWARD", "DROP", "ACCEPT");
    net.iptables.append("filter", "FORWARD", "-m", "conntrack", "--ctstate", "ESTABLISHED", "-j", "ACCEPT");
    net.iptables.append("filter", "FORWARD", "-m", "connmark", "--mark", "0x1/0x1", "-j", "ACCEPT");

    # Create dependency scope.
    depend_scope() depsc;

    # Start processes.
    process_manager() mgr;
    mgr->start("network_lan", {});
    mgr->start("network_serverif", {});
    mgr->start("network_internet", {});
    mgr->start("network_lan_internet_rules", {});
    mgr->start("network_serverif_internet_rules", {});
    mgr->start("network_lan_serverif_rules", {});
    mgr->start("network_lan_dhcp_server", {});
    mgr->start("network_unbound", {});
    mgr->start("network_port_forwarding", {});
    mgr->start("network_start_control_server", {});
}

template network_weak_hostmodel_rules {
    alias("_arg0") dev;
    alias("_arg1") addr;

    concat("INPUT_hostmodel_drop_", dev) drop_chain;

    net.iptables.newchain("filter", drop_chain);
    net.iptables.append("filter", drop_chain, "-j", "DROP");
    net.iptables.append("filter", "INPUT", "-d", addr, "!", "-i", dev, "-j", drop_chain);
}

template network_weak_hostmodel_exception {
    alias("_arg0") dev;
    alias("_arg1") match;

    concat("INPUT_hostmodel_drop_", dev) drop_chain;

    listfrom({"filter", drop_chain}, match, {"-j", "RETURN"}) args;
    net.iptables.insert(args);
}

template network_lan {
    alias("_caller") main;

    # Some configuration.
    var("enp1s0") dev;
    var("192.168.111.1") addr;
    var("24") prefix;
    var("192.168.111.100") dhcp_start;
    var("192.168.111.149") dhcp_end;

    main.depsc->provide("lan_config");

    # Wait for device, set up, wait for link.
    net.backend.waitdevice(dev);
    net.up(dev);
    net.backend.waitlink(dev);

    # Weak host model.
    call("network_weak_hostmodel_rules", {dev, addr});

    # Assign IP address.
    net.ipv4.addr(dev, addr, prefix);

    # Do SNAT for port forwardings when connections originate from the inside.
    net.iptables.append("nat", "POSTROUTING", "-m", "connmark", "--mark", "0x2/0x2", "-j", "SNAT", "--to-source", addr, "--random");

    main.depsc->provide("lan");
}

template network_serverif {
    alias("_caller") main;

    # Some configuration.
    var("enp3s0") dev;
    var("192.168.113.1") addr;
    var("24") prefix;

    main.depsc->provide("serverif_config");

    # Wait for device, set up, wait for link.
    net.backend.waitdevice(dev);
    net.up(dev);
    net.backend.waitlink(dev);

    # Weak host model.
    call("network_weak_hostmodel_rules", {dev, addr});

    # Assign IP address.
    net.ipv4.addr(dev, addr, prefix);

    # Do SNAT for port forwardings when connections originate from the inside.
    net.iptables.append("nat", "POSTROUTING", "-m", "connmark", "--mark", "0x4/0x4", "-j", "SNAT", "--to-source", addr, "--random");

    main.depsc->provide("serverif");
}

template network_internet {
    alias("_caller") main;

    # Some configuration.
    var("enp2s0") pppoe_dev;
    var("MISSING") pppoe_username;
    var("MISSING") pppoe_password;

    # Wait for device, set up, wait for link.
    net.backend.waitdevice(pppoe_dev);
    net.up(pppoe_dev);
    net.backend.waitlink(pppoe_dev);

    log("notice", "PPPoE started");
    log_r("notice", "PPPoE stopped");

    # Start PPPoE.
    call("pppoe", {pppoe_dev, pppoe_username, pppoe_password, "network_internet_pppoe_preup"}) pppoe;

    # Grab configuration.
    var(pppoe.ifname) dev;
    var(pppoe.local_ip) addr;
    var(pppoe.remote_ip) remote_addr;
    var(pppoe.dns_servers) dns_servers;

    to_string(dns_servers) dns_str;
    log("notice", "PPPoE up dev=", dev, " local=", addr, " remote=", remote_addr, " dns=", dns_str);
    log_r("notice", "PPPoE down");

    # Add default route.
    net.ipv4.route("0.0.0.0/0", remote_addr, "20", dev);

    main.depsc->provide("internet");
}

template network_internet_pppoe_preup {
    alias("_arg0") dev;
    alias("_arg1") addr;
    alias("_arg2") remote_ip;
    alias("_arg3") dns_servers;

    # Weak host model.
    call("network_weak_hostmodel_rules", {dev, addr});

    # Drop packets to this system, except some things.
    net.iptables.newchain("filter", "INPUT_internet_drop");
    #net.iptables.append("filter", "INPUT_internet_drop", "-p", "tcp", "--dport", "22", "-j", "RETURN");
    net.iptables.append("filter", "INPUT_internet_drop", "-j", "DROP");
    net.iptables.append("filter", "INPUT", "-i", dev, "-j", "INPUT_internet_drop");

    # Do SNAT for packets going out.
    net.iptables.append("nat", "POSTROUTING", "-o", dev, "-j", "SNAT", "--to-source", addr, "--random");

    # Do MMS clamping.
    net.iptables.append("mangle", "OUTPUT", "-o", dev, "-p", "tcp", "--tcp-flags", "SYN,RST", "SYN", "-j", "TCPMSS", "--clamp-mss-to-pmtu");
    net.iptables.append("mangle", "FORWARD", "-o", dev, "-p", "tcp", "--tcp-flags", "SYN,RST", "SYN", "-j", "TCPMSS", "--clamp-mss-to-pmtu");
}

template network_lan_internet_rules {
    alias("_caller") main;
    main.depsc->depend({"lan"}) lan;
    main.depsc->depend({"internet"}) internet;

    # Add exception to weak host model of internet interface.
    call("network_weak_hostmodel_exception", {internet.dev, {"-i", lan.dev}});
    net.iptables.append("filter", "FORWARD", "-m", "conntrack", "--ctstate", "NEW", "-i", lan.dev, "-o", internet.dev, "-j", "ACCEPT");
}

template network_serverif_internet_rules {
    alias("_caller") main;
    main.depsc->depend({"serverif"}) serverif;
    main.depsc->depend({"internet"}) internet;

    # Allow traffic from LAN to Internet.
    call("network_weak_hostmodel_exception", {internet.dev, {"-i", serverif.dev}});
    net.iptables.append("filter", "FORWARD", "-m", "conntrack", "--ctstate", "NEW", "-i", serverif.dev, "-o", internet.dev, "-j", "ACCEPT");
}

template network_lan_serverif_rules {
    alias("_caller") main;
    main.depsc->depend({"lan"}) lan;
    main.depsc->depend({"serverif"}) serverif;

    # Allow traffic from serverif to LAN.
    call("network_weak_hostmodel_exception", {serverif.dev, {"-i", lan.dev}});
    net.iptables.append("filter", "FORWARD", "-m", "conntrack", "--ctstate", "NEW", "-i", lan.dev, "-o", serverif.dev, "-j", "ACCEPT");

    # Allow traffic from LAN to serverif.
    call("network_weak_hostmodel_exception", {lan.dev, {"-i", serverif.dev}});
    net.iptables.append("filter", "FORWARD", "-m", "conntrack", "--ctstate", "NEW", "-i", serverif.dev, "-o", lan.dev, "-j", "ACCEPT");
}

template network_lan_dhcp_server {
    alias("_caller") main;
    main.depsc->depend({"lan"}) lan;

    # Start DHCP server.
    call("dhcp_server", {lan.addr, lan.prefix, lan.dhcp_start, lan.dhcp_end, {lan.addr}, {lan.addr}});
}

template network_unbound {
    alias("_caller") main;
    main.depsc->depend({"lan_config"}) lan_config;
    main.depsc->depend({"serverif_config"}) serverif_config;

    # Add DNS servers.
    net.dns({"127.0.0.1"}, "20");

    # Build configuration.
    ipv4_net_from_addr_and_prefix(lan_config.addr, lan_config.prefix) lan_network;
    ipv4_net_from_addr_and_prefix(serverif_config.addr, serverif_config.prefix) serverif_network;
    var({
        {lan_network, lan_config.prefix, "allow"},
        {serverif_network, serverif_config.prefix, "allow"}
    }) access_control_rules;

    # Start Unbound.
    call("unbound", {"lan", access_control_rules});
}

template network_port_forwarding {
    alias("_caller") main;

    # Start forwarding.
    call("port_forwarding", {"/var/lib/ncd-port-forwardings.ncdvalue", "network_port_forwarding_rules"}) pf;

    main.depsc->provide("port_forwarding");
}

template network_port_forwarding_rules {
    alias("_caller.main") main;
    alias("_arg0") protocol;
    alias("_arg1") port_start;
    alias("_arg2") port_end;
    alias("_arg3") dest_addr;

    # Get access to lan and serverif configuration.
    main.depsc->depend({"lan_config"}) lan;
    main.depsc->depend({"serverif_config"}) serverif;

    # Wait for Internet interface.
    main.depsc->depend({"internet"}) internet;

    # Build port range string.
    concat(port_start, ":", port_end) port_range;

    # Add rules.
    net.iptables.append("nat", "PREROUTING", "-d", internet.addr, "-p", protocol, "--dport", port_range, "-i", lan.dev, "-j", "CONNMARK", "--set-xmark", "0x3/0x3");
    net.iptables.append("nat", "PREROUTING", "-d", internet.addr, "-p", protocol, "--dport", port_range, "-i", serverif.dev, "-j", "CONNMARK", "--set-xmark", "0x5/0x5");
    net.iptables.append("nat", "PREROUTING", "-d", internet.addr, "-p", protocol, "--dport", port_range, "-i", internet.dev, "-j", "CONNMARK", "--set-xmark", "0x1/0x1");
    net.iptables.append("nat", "PREROUTING", "-d", internet.addr, "-p", protocol, "--dport", port_range, "-j", "DNAT", "--to-destination", dest_addr);
}

template network_start_control_server {
    alias("_caller") main;
    main.depsc->depend({"lan_config"}) lan_config;

    # Start control server.
    call("network_control_server", {"/run/ncd-control.socket",
        "network_control_list_port_forwardings",
        "network_control_add_port_forwarding",
        "network_control_remove_port_forwarding"});
}

template network_control_list_port_forwardings {
    alias("_caller.main") main;

    main.depsc->depend({"port_forwarding"}) port_forwarding;
    var(port_forwarding.pf.map.keys) port_forwardings;
}

template network_control_add_port_forwarding {
    alias("_caller.main") main;
    alias("_arg0") protocol;
    alias("_arg1") port_start;
    alias("_arg2") port_end;
    alias("_arg3") dest_addr;

    var("") try_error_text;
    try("network_verify_port_forwarding_try", {}) verify_try;

    If (verify_try.succeeded) {
        main.depsc->depend({"port_forwarding"}) port_forwarding;

        call("port_forwarding_add", {"_caller.port_forwarding.pf", protocol, port_start, port_end, dest_addr}) call;
        alias("call.succeeded") succeeded;
        alias("call.error_text") error_text;
    } Else {
        var("false") succeeded;
        alias("try_error_text") error_text;
    } branch;

    alias("branch.succeeded") succeeded;
    alias("branch.error_text") error_text;
}

template network_control_remove_port_forwarding {
    alias("_caller.main") main;
    alias("_arg0") protocol;
    alias("_arg1") port_start;
    alias("_arg2") port_end;
    alias("_arg3") dest_addr;

    main.depsc->depend({"port_forwarding"}) port_forwarding;

    call("port_forwarding_remove", {"_caller.port_forwarding.pf", protocol, port_start, port_end, dest_addr}) call;
    alias("call.succeeded") succeeded;
    alias("call.error_text") error_text;
}

template network_verify_port_forwarding_try {
    alias("_caller") c;

    c.main.depsc->depend({"lan_config"}) lan;
    c.main.depsc->depend({"serverif_config"}) serverif;

    net.ipv4.addr_in_network(c.dest_addr, lan.addr, lan.prefix) in_lan;
    net.ipv4.addr_in_network(c.dest_addr, serverif.addr, serverif.prefix) in_serverif;

    If (in_lan) {
        print();
    }
    Elif (in_serverif) {
        print();
    }
    Else {
        c.try_error_text->set("Destination address does not belong to any permitted network.");
        _try->assert("false");
    };
}