65 lines
2.2 KiB
OCaml
65 lines
2.2 KiB
OCaml
(* Copyright (C) 2015, Thomas Leonard <thomas.leonard@unikernel.com>
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See the README file for details. *)
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open Fw_utils
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type port = int
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type host =
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[ `Client of client_link | `Firewall | `NetVM | `External of Ipaddr.t ]
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type transport_header = [`TCP of Tcp.Tcp_packet.t
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|`UDP of Udp_packet.t
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|`ICMP of Icmpv4_packet.t]
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type ('src, 'dst) t = {
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ipv4_header : Ipv4_packet.t;
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transport_header : transport_header;
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transport_payload : Cstruct.t;
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src : 'src;
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dst : 'dst;
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}
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let pp_transport_header f = function
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| `ICMP h -> Icmpv4_packet.pp f h
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| `TCP h -> Tcp.Tcp_packet.pp f h
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| `UDP h -> Udp_packet.pp f h
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let pp_host fmt = function
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| `Client c -> Ipaddr.V4.pp fmt (c#other_ip)
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| `Unknown_client ip -> Format.fprintf fmt "unknown-client(%a)" Ipaddr.pp ip
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| `NetVM -> Format.pp_print_string fmt "net-vm"
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| `External ip -> Format.fprintf fmt "external(%a)" Ipaddr.pp ip
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| `Firewall -> Format.pp_print_string fmt "firewall(client-gw)"
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let to_mirage_nat_packet t : Nat_packet.t =
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match t.transport_header with
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| `TCP h -> `IPv4 (t.ipv4_header, (`TCP (h, t.transport_payload)))
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| `UDP h -> `IPv4 (t.ipv4_header, (`UDP (h, t.transport_payload)))
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| `ICMP h -> `IPv4 (t.ipv4_header, (`ICMP (h, t.transport_payload)))
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let of_mirage_nat_packet ~src ~dst packet : ('a, 'b) t option =
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let `IPv4 (ipv4_header, ipv4_payload) = packet in
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let transport_header, transport_payload = match ipv4_payload with
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| `TCP (h, p) -> `TCP h, p
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| `UDP (h, p) -> `UDP h, p
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| `ICMP (h, p) -> `ICMP h, p
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in
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Some {
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ipv4_header;
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transport_header;
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transport_payload;
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src;
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dst;
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}
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(* possible actions to take for a packet: *)
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type action = [
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| `Accept (* Send to destination, unmodified. *)
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| `NAT (* Rewrite source field to the firewall's IP, with a fresh source port.
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Also, add translation rules for future traffic in both directions,
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between these hosts on these ports, and corresponding ICMP error traffic. *)
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| `NAT_to of host * port (* As for [`NAT], but also rewrite the packet's
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destination fields so it will be sent to [host:port]. *)
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| `Drop of string (* Drop packet for this reason. *)
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]
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