-module(ssh_tunnel). -doc """ Module for creating SSH tunnels using `ssh`. [https://github.com/drowzy/ssh_tunnel] It provides functions to create forwarded ssh channels, similair to how other channels can be created using `ssh_connection`. There are two type of channels supported * `directtcp-ip` - Forwards a port from the client machine to the remote machine. This is the same as `ssh -nNT -L 8080:forward.example.com:9000 user@sshserver.example.com` * `direct-streamlocal` - Forwards to a unix domain socket. This is the same as `ssh -nNT -L 8080:/var/lib/mysql/mysql.sock user@sshserver.example.com` When using `direct_tcpip/3` or `direct_stream_local/2` directly there will not be any local port or socket bound, this can either be done using `ssh_tunnel` or by manually sending data with `ssh_connection:send/3`. Although `connect/3` can be used to connect to the remote host, other methods are supported. One can use [SSHex](https://github.com/rubencaro/sshex), `ssh:connect/3` for instance. ## Tunnels Tunnels are on-demand TCP servers and are bound listeners to either a port or a path. The tunnel will handle relaying TCP messages to the ssh connection and back. ## Examples ``` {ok, SshRef} = ssh_tunnel:connect("sshserver.example.com", 22, []), {ok, Pid} = ssh_tunnel:start_tunnel(Pid, {tcpip, {8080, {"192.168.90.15", 80}}}), % Send a TCP message for instance HTTP Resp = HTTPoison.get!("127.0.0.1:8080"), io:format("Received body: ~p\n", [Resp]) ``` """. -export([start_tunnel/3]). -export([connect/0, connect/3, direct_tcpip/3, direct_stream_local/2, open_channel/6]). -define(DIRECT_TCPIP, "direct-tcpip"). -define(STREAM_LOCAL, "direct-streamlocal@openssh.com"). -define(INI_WINDOW_SIZE, 1024 * 1024). -define(MAX_PACKET_SIZE, 32 * 1024). -type location() :: {string(), integer()}. connect() -> connect({127,0,0,1}, 22, []). -doc """ Create a connetion to a remote host with the provided options. This function is mostly used as convenience wrapper around `ssh:connect/3` and does not support all options. returns: `{ok, Connection}` or `{error, Reason}`. [https://manpages.debian.org/stretch/erlang-manpages/ssh.3erl.en.html] """. -spec connect(list()|tuple(), integer(), list()) -> {ok, pid()} | {error, term()}. connect(Host, Port, Opts) when (is_list(Host) orelse is_tuple(Host)), is_integer(Port), is_list(Opts) -> Config = defaults(Opts), ssh:connect(Host, Port, Config). -doc """ Starts a SSHTunnel.Tunnel process. The tunnel will listen to either a local port or local path and handle passing messages between the TCP client and ssh connection. ## Examples {ok, SSH} = ssh_tunnel:connect("sshserver.example.com", 22), {ok, Pid} = ssh_tunnel:start_tunnel(Pid, tcp, {8080, {"192.168.90.15", 80}}) # Send a TCP message %HTTPoison.Response{body: body} = HTTPoison.get!("127.0.0.1:8080") IO.puts("Received body: #{body}) """. -spec start_tunnel(pid(), tcp|local, tuple()|integer()) -> {ok, pid()} | {error, term()}. start_tunnel(Pid, Transport, To) when (is_tuple(To) orelse is_integer(To)) , (Transport==tcp orelse Transport==local) -> case {Transport, To} of {tcp, ToPort} when is_integer(ToPort) -> direct_tcpip(Pid, {"localhost", ToPort}, {"localhost", ToPort}); {tcp, {From, To}} when is_integer(From), is_integer(To) -> direct_tcpip(Pid, {"localhost", From}, {"localhost", To}); {tcp, {From, {ToHost, ToPort}=To}} when is_integer(From), is_list(ToHost), is_integer(ToPort) -> direct_tcpip(Pid, {"localhost", From}, To); {tcp, {From, {ToHost, ToPort}=To}} when is_integer(From), is_list(ToHost), is_integer(ToPort) -> direct_tcpip(Pid, {"localhost", From}, To); {tcp, {{FromHost, FromPort}=From, {ToHost, ToPort}=To}} when is_list(FromHost), is_integer(FromPort), is_list(ToHost), is_integer(ToPort) -> direct_tcpip(Pid, From, To); {local, To} when is_list(To) -> direct_stream_local(Pid, To) end. -doc """ Creates a ssh directtcp-ip forwarded channel to a remote port. The returned channel together with a ssh connection reference (returned from `ssh:connect/4`) can be used to send messages with `ssh_connection:send/3` returns: `{ok, channel}` or `{error, reason}`. ## Examples: msg = "GET / HTTP/1.1\r\nHost: localhost:8080\r\nUser-Agent: curl/7.47.0\r\nAccept: */*\r\n\r\n" {ok, Pid} = ssh_tunnel:connect("192.168.1.10", 22), {ok, Ch} = ssh_tunnel:direct_tcpip(Pid, {"127.0.0.1", 8080}, {"192.168.1.10", 80}), ok = ssh_connection:send(Pid, Ch, Msg), recieve do {ssh_cm, _, {data, Channel, _, Data}} -> io:format("Data: ~p\n", [Data]) end """. -spec direct_tcpip(pid(), From::location(), To::location()) -> {ok, integer()} | {error, term()}. direct_tcpip(Pid, {OrigHost, OrigPort} = _From, {RemHost, RemPort} = _To) when is_pid(Pid) -> LocH = list_to_binary(OrigHost), RemH = list_to_binary(RemHost), RemLen = byte_size(RemH), LocLen = byte_size(LocH), Msg = <>, open_channel(Pid, ?DIRECT_TCPIP, Msg, ?INI_WINDOW_SIZE, ?MAX_PACKET_SIZE, infinity). -doc """ Creates a ssh stream local-forward channel to a remote unix domain socket. It sends the request that the server make a connection to its local Unix domain socket. The returned channel together with a ssh connection reference (returned from `ssh:connect/4`) can be used to send messages with `ssh_connection:send/3`. returns: `{ok, Channel}` or `{error, Reason}`. Ex: ``` msg = "GET /images/json HTTP/1.1\r\nHost: /var/run/docker.sock\r\nAccept: */*\r\n\r\n" {ok, Pid} = ssh_tunnel:connect("192.168.90.15", 22), {ok, Ch} = ssh_tunnel:direct_stream_local(Pid, "/var/run/docker.sock"), ok = ssh_connection:send(Pid, Ch, Msg) ``` """. -spec direct_stream_local(pid(), string()) -> {ok, integer()} | {error, term()}. direct_stream_local(Pid, SocketPath) when is_pid(Pid), is_list(SocketPath) -> SPath = list_to_binary(SocketPath), Msg = <<(byte_size(SPath)):32/integer, SPath/binary, 0:32, 0:32>>, open_channel(Pid, ?STREAM_LOCAL, Msg, ?INI_WINDOW_SIZE, ?MAX_PACKET_SIZE, infinity). open_channel(Pid, Type, Msg, WindowSize, MaxPktSz, Timeout) -> case ssh_connection_handler:open_channel(Pid,Type,Msg,WindowSize,MaxPktSz,Timeout) of {open, Ch} -> {ok, Ch}; {open_error, _, Reason, _} -> {error, to_string(Reason)}; {error, Reason} -> {error, inet:format_error(Reason)} end. defaults(Opts) -> [ {user_interaction, false}, {silently_accept_hosts, true} | Opts ]. to_string(A) when is_atom(A) -> atom_to_list(A); to_string(B) when is_binary(B) -> binary_to_list(B); to_string(B) when is_list(B) -> B.