From 4eb60b4d23befd64250b8aca456f082e5d212878 Mon Sep 17 00:00:00 2001 From: Hans Nilsson Date: Fri, 2 Mar 2018 18:02:48 +0100 Subject: ssh: Simplification of using fun:s as exec subsystems --- lib/ssh/src/ssh_cli.erl | 270 +++++++++++++++++++++------------- lib/ssh/src/ssh_options.erl | 8 +- lib/ssh/test/ssh_connection_SUITE.erl | 104 ++++++++++--- 3 files changed, 255 insertions(+), 127 deletions(-) diff --git a/lib/ssh/src/ssh_cli.erl b/lib/ssh/src/ssh_cli.erl index 958c342f5f..783f2f80c0 100644 --- a/lib/ssh/src/ssh_cli.erl +++ b/lib/ssh/src/ssh_cli.erl @@ -118,42 +118,53 @@ handle_ssh_msg({ssh_cm, ConnectionHandler, write_chars(ConnectionHandler, ChannelId, Chars), {ok, State#state{pty = Pty, buf = NewBuf}}; -handle_ssh_msg({ssh_cm, ConnectionHandler, - {shell, ChannelId, WantReply}}, State) -> +handle_ssh_msg({ssh_cm, ConnectionHandler, {shell, ChannelId, WantReply}}, State) -> NewState = start_shell(ConnectionHandler, State), - ssh_connection:reply_request(ConnectionHandler, WantReply, - success, ChannelId), - {ok, NewState#state{channel = ChannelId, - cm = ConnectionHandler}}; - -handle_ssh_msg({ssh_cm, ConnectionHandler, - {exec, ChannelId, WantReply, Cmd}}, #state{exec=undefined, - shell=?DEFAULT_SHELL} = State) -> - {Reply, Status} = exec(Cmd), - write_chars(ConnectionHandler, - ChannelId, io_lib:format("~p\n", [Reply])), - ssh_connection:reply_request(ConnectionHandler, WantReply, - success, ChannelId), - ssh_connection:exit_status(ConnectionHandler, ChannelId, Status), - ssh_connection:send_eof(ConnectionHandler, ChannelId), - {stop, ChannelId, State#state{channel = ChannelId, cm = ConnectionHandler}}; - -handle_ssh_msg({ssh_cm, ConnectionHandler, - {exec, ChannelId, WantReply, _Cmd}}, #state{exec = undefined} = State) -> - write_chars(ConnectionHandler, ChannelId, 1, "Prohibited.\n"), ssh_connection:reply_request(ConnectionHandler, WantReply, success, ChannelId), - ssh_connection:exit_status(ConnectionHandler, ChannelId, 255), - ssh_connection:send_eof(ConnectionHandler, ChannelId), - {stop, ChannelId, State#state{channel = ChannelId, cm = ConnectionHandler}}; - -handle_ssh_msg({ssh_cm, ConnectionHandler, - {exec, ChannelId, WantReply, Cmd}}, State) -> - NewState = start_shell(ConnectionHandler, Cmd, State), - ssh_connection:reply_request(ConnectionHandler, WantReply, - success, ChannelId), {ok, NewState#state{channel = ChannelId, cm = ConnectionHandler}}; +handle_ssh_msg({ssh_cm, ConnectionHandler, {exec, ChannelId, WantReply, Cmd}}, S0) -> + case + case S0#state.exec of + {direct,F} -> + %% Exec called and a Fun or MFA is defined to use. The F returns the + %% value to return. + exec_direct(ConnectionHandler, F, Cmd); + + undefined when S0#state.shell == ?DEFAULT_SHELL -> + %% Exec called and the shell is the default shell (= Erlang shell). + %% To be exact, eval the term as an Erlang term (but not using the + %% ?DEFAULT_SHELL directly). This disables banner, prompts and such. + exec_in_erlang_default_shell(Cmd); + + undefined -> + %% Exec called, but the a shell other than the default shell is defined. + %% No new exec shell is defined, so don't execute! + %% We don't know if it is intended to use the new shell or not. + {"Prohibited.", 255, 1}; + + _ -> + %% Exec called and a Fun or MFA is defined to use. The F communicates via + %% standard io:write/read. + %% Kept for compatibility. + S1 = start_exec_shell(ConnectionHandler, Cmd, S0), + ssh_connection:reply_request(ConnectionHandler, WantReply, success, ChannelId), + {ok, S1} + end + of + {Reply, Status, Type} -> + write_chars(ConnectionHandler, ChannelId, Type, Reply), + ssh_connection:reply_request(ConnectionHandler, WantReply, success, ChannelId), + ssh_connection:exit_status(ConnectionHandler, ChannelId, Status), + ssh_connection:send_eof(ConnectionHandler, ChannelId), + {stop, ChannelId, S0#state{channel = ChannelId, cm = ConnectionHandler}}; + + {ok, S} -> + {ok, S#state{channel = ChannelId, + cm = ConnectionHandler}} + end; + handle_ssh_msg({ssh_cm, _ConnectionHandler, {eof, _ChannelId}}, State) -> {ok, State}; @@ -259,35 +270,7 @@ to_group(Data, Group) -> end, to_group(Tail, Group). -exec(Cmd) -> - case eval(parse(scan(Cmd))) of - {error, _} -> - {Cmd, 0}; %% This should be an external call - Term -> - Term - end. - -scan(Cmd) -> - erl_scan:string(Cmd). - -parse({ok, Tokens, _}) -> - erl_parse:parse_exprs(Tokens); -parse(Error) -> - Error. - -eval({ok, Expr_list}) -> - case (catch erl_eval:exprs(Expr_list, - erl_eval:new_bindings())) of - {value, Value, _NewBindings} -> - {Value, 0}; - {'EXIT', {Error, _}} -> - {Error, -1}; - Error -> - {Error, -1} - end; -eval(Error) -> - {Error, -1}. - +%%-------------------------------------------------------------------- %%% io_request, handle io requests from the user process, %%% Note, this is not the real I/O-protocol, but the mockup version %%% used between edlin and a user_driver. The protocol tags are @@ -506,53 +489,130 @@ bin_to_list(L) when is_list(L) -> bin_to_list(I) when is_integer(I) -> I. + +%%-------------------------------------------------------------------- start_shell(ConnectionHandler, State) -> - Shell = State#state.shell, - ConnectionInfo = ssh_connection_handler:connection_info(ConnectionHandler, - [peer, user]), - ShellFun = case is_function(Shell) of - true -> - User = proplists:get_value(user, ConnectionInfo), - case erlang:fun_info(Shell, arity) of - {arity, 1} -> - fun() -> Shell(User) end; - {arity, 2} -> - {_, PeerAddr} = proplists:get_value(peer, ConnectionInfo), - fun() -> Shell(User, PeerAddr) end; - _ -> - Shell - end; - _ -> - Shell - end, - Echo = get_echo(State#state.pty), - Group = group:start(self(), ShellFun, [{echo, Echo}]), - State#state{group = Group, buf = empty_buf()}. - -start_shell(_ConnectionHandler, Cmd, #state{exec={M, F, A}} = State) -> - Group = group:start(self(), {M, F, A++[Cmd]}, [{echo, false}]), - State#state{group = Group, buf = empty_buf()}; -start_shell(ConnectionHandler, Cmd, #state{exec=Shell} = State) when is_function(Shell) -> - - ConnectionInfo = ssh_connection_handler:connection_info(ConnectionHandler, - [peer, user]), - User = proplists:get_value(user, ConnectionInfo), - ShellFun = - case erlang:fun_info(Shell, arity) of - {arity, 1} -> - fun() -> Shell(Cmd) end; - {arity, 2} -> - fun() -> Shell(Cmd, User) end; - {arity, 3} -> - {_, PeerAddr} = proplists:get_value(peer, ConnectionInfo), - fun() -> Shell(Cmd, User, PeerAddr) end; - _ -> - Shell - end, - Echo = get_echo(State#state.pty), - Group = group:start(self(), ShellFun, [{echo,Echo}]), - State#state{group = Group, buf = empty_buf()}. + ShellSpawner = + case State#state.shell of + Shell when is_function(Shell, 1) -> + [{user,User}] = ssh_connection_handler:connection_info(ConnectionHandler, [user]), + fun() -> Shell(User) end; + Shell when is_function(Shell, 2) -> + ConnectionInfo = + ssh_connection_handler:connection_info(ConnectionHandler, [peer, user]), + User = proplists:get_value(user, ConnectionInfo), + {_, PeerAddr} = proplists:get_value(peer, ConnectionInfo), + fun() -> Shell(User, PeerAddr) end; + {_,_,_} = Shell -> + Shell + end, + State#state{group = group:start(self(), ShellSpawner, [{echo, get_echo(State#state.pty)}]), + buf = empty_buf()}. + +%%-------------------------------------------------------------------- +start_exec_shell(ConnectionHandler, Cmd, State) -> + ExecShellSpawner = + case State#state.exec of + ExecShell when is_function(ExecShell, 1) -> + fun() -> ExecShell(Cmd) end; + ExecShell when is_function(ExecShell, 2) -> + [{user,User}] = ssh_connection_handler:connection_info(ConnectionHandler, [user]), + fun() -> ExecShell(Cmd, User) end; + ExecShell when is_function(ExecShell, 3) -> + ConnectionInfo = + ssh_connection_handler:connection_info(ConnectionHandler, [peer, user]), + User = proplists:get_value(user, ConnectionInfo), + {_, PeerAddr} = proplists:get_value(peer, ConnectionInfo), + fun() -> ExecShell(Cmd, User, PeerAddr) end; + {M,F,A} -> + {M, F, A++[Cmd]} + end, + State#state{group = group:start(self(), ExecShellSpawner, [{echo,false}]), + buf = empty_buf()}. + +%%-------------------------------------------------------------------- +exec_in_erlang_default_shell(Cmd) -> + case eval(parse(scan(Cmd))) of + {ok, Term} -> + {io_lib:format("~p\n", [Term]), 0, 0}; + {error, Error} when is_atom(Error) -> + {io_lib:format("Error in ~p: ~p\n", [Cmd,Error]), -1, 1}; + _ -> + {io_lib:format("Error: ~p\n", [Cmd]), -1, 1} + end. + +scan(Cmd) -> + erl_scan:string(Cmd). + +parse({ok, Tokens, _}) -> + erl_parse:parse_exprs(Tokens); +parse(Error) -> + Error. +eval({ok, Expr_list}) -> + case (catch erl_eval:exprs(Expr_list, + erl_eval:new_bindings())) of + {value, Value, _NewBindings} -> + {ok, Value}; + {'EXIT', {Error, _}} -> + {error, Error}; + {error, Error} -> + {error, Error}; + Error -> + {error, Error} + end; +eval({error,Error}) -> + {error, Error}; +eval(Error) -> + {error, Error}. + +%%-------------------------------------------------------------------- +exec_direct(ConnectionHandler, ExecSpec, Cmd) -> + try + case ExecSpec of + _ when is_function(ExecSpec, 1) -> + ExecSpec(Cmd); + _ when is_function(ExecSpec, 2) -> + [{user,User}] = ssh_connection_handler:connection_info(ConnectionHandler, [user]), + ExecSpec(Cmd, User); + _ when is_function(ExecSpec, 3) -> + ConnectionInfo = + ssh_connection_handler:connection_info(ConnectionHandler, [peer, user]), + User = proplists:get_value(user, ConnectionInfo), + {_, PeerAddr} = proplists:get_value(peer, ConnectionInfo), + ExecSpec(Cmd, User, PeerAddr) + end + of + Reply -> + return_direct_exec_reply(Reply, Cmd) + catch + C:Error -> + {io_lib:format("Error in \"~s\": ~p ~p~n", [Cmd,C,Error]), -1, 1} + end. + + + +return_direct_exec_reply(Reply, Cmd) -> + case fmt_exec_repl(Reply) of + {ok,S} -> + {S, 0, 0}; + {error,S} -> + {io_lib:format("Error in \"~s\": ~s~n", [Cmd,S]), -1, 1} + end. + +fmt_exec_repl({T,A}) when T==ok ; T==error -> + try + {T, io_lib:format("~s",[A])} + catch + error:badarg -> + {T, io_lib:format("~p", [A])}; + C:Err -> + {error, io_lib:format("~p:~p~n",[C,Err])} + end; +fmt_exec_repl(Other) -> + {error, io_lib:format("Bad exec-plugin return: ~p",[Other])}. + +%%-------------------------------------------------------------------- % Pty can be undefined if the client never sets any pty options before % starting the shell. get_echo(undefined) -> diff --git a/lib/ssh/src/ssh_options.erl b/lib/ssh/src/ssh_options.erl index 1e10f72956..c05293d1ae 100644 --- a/lib/ssh/src/ssh_options.erl +++ b/lib/ssh/src/ssh_options.erl @@ -275,10 +275,12 @@ default(server) -> class => user_options }, - {exec, def} => % FIXME: need some archeology.... + {exec, def} => #{default => undefined, - chk => fun({M,F,_}) -> is_atom(M) andalso is_atom(F); - (V) -> is_function(V) + chk => fun({direct, V}) -> check_function1(V) orelse check_function2(V) orelse check_function3(V); + %% Compatibility (undocumented): + ({M,F,A}) -> is_atom(M) andalso is_atom(F) andalso is_list(A); + (V) -> check_function1(V) orelse check_function2(V) orelse check_function3(V) end, class => user_options }, diff --git a/lib/ssh/test/ssh_connection_SUITE.erl b/lib/ssh/test/ssh_connection_SUITE.erl index 9587c0c251..257f2f70d7 100644 --- a/lib/ssh/test/ssh_connection_SUITE.erl +++ b/lib/ssh/test/ssh_connection_SUITE.erl @@ -50,6 +50,13 @@ all() -> start_shell, start_shell_exec, start_shell_exec_fun, + start_shell_exec_fun2, + start_shell_exec_fun3, + start_shell_exec_direct_fun, + start_shell_exec_direct_fun2, + start_shell_exec_direct_fun3, + start_shell_exec_direct_fun1_error, + start_shell_exec_direct_fun1_error_type, start_shell_sock_exec_fun, start_shell_sock_daemon_exec, connect_sock_not_tcp, @@ -522,7 +529,7 @@ start_shell_exec(Config) when is_list(Config) -> {Pid, Host, Port} = ssh_test_lib:daemon([{system_dir, SysDir}, {user_dir, UserDir}, {password, "morot"}, - {exec, {?MODULE,ssh_exec,[]}} ]), + {exec, {?MODULE,ssh_exec_echo,[]}} ]), ConnectionRef = ssh_test_lib:connect(Host, Port, [{silently_accept_hosts, true}, {user, "foo"}, @@ -535,7 +542,7 @@ start_shell_exec(Config) when is_list(Config) -> success = ssh_connection:exec(ConnectionRef, ChannelId0, "testing", infinity), receive - {ssh_cm, ConnectionRef, {data, _ChannelId, 0, <<"testing\r\n">>}} -> + {ssh_cm, ConnectionRef, {data, _ChannelId, 0, <<"echo testing\r\n">>}} -> ok after 5000 -> ct:fail("Exec Timeout") @@ -618,10 +625,49 @@ exec_erlang_term_non_default_shell(Config) when is_list(Config) -> TestResult. %%-------------------------------------------------------------------- -start_shell_exec_fun() -> - [{doc, "start shell to exec command"}]. +start_shell_exec_fun(Config) -> + do_start_shell_exec_fun(fun ssh_exec_echo/1, + "testing", <<"echo testing\r\n">>, 0, + Config). + +start_shell_exec_fun2(Config) -> + do_start_shell_exec_fun(fun ssh_exec_echo/2, + "testing", <<"echo foo testing\r\n">>, 0, + Config). + +start_shell_exec_fun3(Config) -> + do_start_shell_exec_fun(fun ssh_exec_echo/3, + "testing", <<"echo foo testing\r\n">>, 0, + Config). + +start_shell_exec_direct_fun(Config) -> + do_start_shell_exec_fun({direct, fun ssh_exec_direct_echo/1}, + "testing", <<"echo testing\n">>, 0, + Config). + +start_shell_exec_direct_fun2(Config) -> + do_start_shell_exec_fun({direct, fun ssh_exec_direct_echo/2}, + "testing", <<"echo foo testing">>, 0, + Config). + +start_shell_exec_direct_fun3(Config) -> + do_start_shell_exec_fun({direct, fun ssh_exec_direct_echo/3}, + "testing", <<"echo foo testing">>, 0, + Config). + +start_shell_exec_direct_fun1_error(Config) -> + do_start_shell_exec_fun({direct, fun ssh_exec_direct_echo_error_return/1}, + "testing", <<"Error in \"testing\": {bad}\n">>, 1, + Config). + +start_shell_exec_direct_fun1_error_type(Config) -> + do_start_shell_exec_fun({direct, fun ssh_exec_direct_echo_error_return_type/1}, + "testing", <<"Error in \"testing\": Bad exec-plugin return: very_bad\n">>, 1, + Config). + + -start_shell_exec_fun(Config) when is_list(Config) -> +do_start_shell_exec_fun(Fun, Command, Expect, ExpectType, Config) -> PrivDir = proplists:get_value(priv_dir, Config), UserDir = filename:join(PrivDir, nopubkey), % to make sure we don't use public-key-auth file:make_dir(UserDir), @@ -629,7 +675,7 @@ start_shell_exec_fun(Config) when is_list(Config) -> {Pid, Host, Port} = ssh_test_lib:daemon([{system_dir, SysDir}, {user_dir, UserDir}, {password, "morot"}, - {exec, fun ssh_exec/1}]), + {exec, Fun}]), ConnectionRef = ssh_test_lib:connect(Host, Port, [{silently_accept_hosts, true}, {user, "foo"}, @@ -639,14 +685,19 @@ start_shell_exec_fun(Config) when is_list(Config) -> {ok, ChannelId0} = ssh_connection:session_channel(ConnectionRef, infinity), - success = ssh_connection:exec(ConnectionRef, ChannelId0, - "testing", infinity), + success = ssh_connection:exec(ConnectionRef, ChannelId0, Command, infinity), receive - {ssh_cm, ConnectionRef, {data, _ChannelId, 0, <<"testing\r\n">>}} -> + {ssh_cm, ConnectionRef, {data, _ChannelId, ExpectType, Expect}} -> ok after 5000 -> - ct:fail("Exec Timeout") + receive + Other -> + ct:pal("Received other:~n~p",[Other]), + ct:fail("Unexpected response") + after 0 -> + ct:fail("Exec Timeout") + end end, ssh:close(ConnectionRef), @@ -664,7 +715,7 @@ start_shell_sock_exec_fun(Config) when is_list(Config) -> {Pid, HostD, Port} = ssh_test_lib:daemon([{system_dir, SysDir}, {user_dir, UserDir}, {password, "morot"}, - {exec, fun ssh_exec/1}]), + {exec, fun ssh_exec_echo/1}]), Host = ssh_test_lib:ntoa(ssh_test_lib:mangle_connect_address(HostD)), {ok, Sock} = ssh_test_lib:gen_tcp_connect(Host, Port, [{active,false}]), @@ -680,7 +731,7 @@ start_shell_sock_exec_fun(Config) when is_list(Config) -> "testing", infinity), receive - {ssh_cm, ConnectionRef, {data, _ChannelId, 0, <<"testing\r\n">>}} -> + {ssh_cm, ConnectionRef, {data, _ChannelId, 0, <<"echo testing\r\n">>}} -> ok after 5000 -> ct:fail("Exec Timeout") @@ -704,7 +755,7 @@ start_shell_sock_daemon_exec(Config) -> {ok, _Pid} = ssh:daemon(Ss, [{system_dir, SysDir}, {user_dir, UserDir}, {password, "morot"}, - {exec, fun ssh_exec/1}]) + {exec, fun ssh_exec_echo/1}]) end), {ok,Sc} = gen_tcp:accept(Sl), {ok,ConnectionRef} = ssh:connect(Sc, [{silently_accept_hosts, true}, @@ -719,7 +770,7 @@ start_shell_sock_daemon_exec(Config) -> "testing", infinity), receive - {ssh_cm, ConnectionRef, {data, _ChannelId, 0, <<"testing\r\n">>}} -> + {ssh_cm, ConnectionRef, {data, _ChannelId, 0, <<"echo testing\r\n">>}} -> ok after 5000 -> ct:fail("Exec Timeout") @@ -830,7 +881,7 @@ stop_listener(Config) when is_list(Config) -> {Pid0, Host, Port} = ssh_test_lib:daemon([{system_dir, SysDir}, {user_dir, UserDir}, {password, "morot"}, - {exec, fun ssh_exec/1}]), + {exec, fun ssh_exec_echo/1}]), ConnectionRef0 = ssh_test_lib:connect(Host, Port, [{silently_accept_hosts, true}, {user, "foo"}, @@ -850,7 +901,7 @@ stop_listener(Config) when is_list(Config) -> success = ssh_connection:exec(ConnectionRef0, ChannelId0, "testing", infinity), receive - {ssh_cm, ConnectionRef0, {data, ChannelId0, 0, <<"testing\r\n">>}} -> + {ssh_cm, ConnectionRef0, {data, ChannelId0, 0, <<"echo testing\r\n">>}} -> ok after 5000 -> ct:fail("Exec Timeout") @@ -859,7 +910,7 @@ stop_listener(Config) when is_list(Config) -> case ssh_test_lib:daemon(Port, [{system_dir, SysDir}, {user_dir, UserDir}, {password, "potatis"}, - {exec, fun ssh_exec/1}]) of + {exec, fun ssh_exec_echo/1}]) of {Pid1, Host, Port} -> ConnectionRef1 = ssh_test_lib:connect(Host, Port, [{silently_accept_hosts, true}, {user, "foo"}, @@ -1070,7 +1121,22 @@ start_our_shell(_User, _Peer) -> %% Don't actually loop, just exit end). -ssh_exec(Cmd) -> + +ssh_exec_echo(Cmd) -> spawn(fun() -> - io:format(Cmd ++ "\n") + io:format("echo "++Cmd ++ "\n") end). + +ssh_exec_echo(Cmd, User) -> + spawn(fun() -> + io:format(io_lib:format("echo ~s ~s\n",[User,Cmd])) + end). +ssh_exec_echo(Cmd, User, _PeerAddr) -> + ssh_exec_echo(Cmd,User). + +ssh_exec_direct_echo(Cmd) -> {ok, io_lib:format("echo ~s~n",[Cmd])}. +ssh_exec_direct_echo(Cmd, User) -> {ok, io_lib:format("echo ~s ~s",[User,Cmd])}. +ssh_exec_direct_echo(Cmd, User, _PeerAddr) -> ssh_exec_direct_echo(Cmd,User). + +ssh_exec_direct_echo_error_return(_Cmd) -> {error, {bad}}. +ssh_exec_direct_echo_error_return_type(_Cmd) -> very_bad. -- cgit v1.2.3 From 3eced27f96d87eac1fc90325d7030167805309a1 Mon Sep 17 00:00:00 2001 From: Hans Nilsson Date: Thu, 8 Mar 2018 16:34:21 +0100 Subject: ssh: Document the exec option --- lib/ssh/doc/src/ssh.xml | 93 +++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 86 insertions(+), 7 deletions(-) diff --git a/lib/ssh/doc/src/ssh.xml b/lib/ssh/doc/src/ssh.xml index acf94ff6af..d36be8431c 100644 --- a/lib/ssh/doc/src/ssh.xml +++ b/lib/ssh/doc/src/ssh.xml @@ -67,24 +67,41 @@ boolean() =

true | false

 + string() =

[byte()]

 + ssh_daemon_ref() =

opaque() - as returned by ssh:daemon/[1,2,3]

 + + ok_error(OKtype) = +

{ok,OKtype} | {error, term()}

 + + ok_error() = +

ok_error(term())

 + ssh_connection_ref() =

opaque() - as returned by ssh:connect/3

 + ip_address() = -

inet::ip_address

 +

inet::ip_address()

 + + port_number() = +

inet::port_number()

 + subsystem_spec() =

{subsystem_name(), {channel_callback(), channel_init_args()}}

 + subsystem_name() =

string()

 + channel_callback() =

atom() - Name of the Erlang module implementing the subsystem using the ssh_channel behavior, see ssh_channel(3)

 + key_cb() =

atom() | {atom(), list()}

@@ -94,6 +111,7 @@ case maybe.

list() - List of options that can be passed to the callback module.

 + channel_init_args() =

list()

 @@ -478,8 +496,8 @@ Option = client_version | server_version | user | peer | sockname Value = [option_value()] option_value() = {{Major::integer(), Minor::integer()}, VersionString::string()} | - User::string() | Peer::{inet:hostname(), {inet::ip_adress(), inet::port_number()}} | - Sockname::{inet::ip_adress(), inet::port_number()} + User::string() | Peer::{inet:hostname(), {ip_address(), port_number()}} | + Sockname::{ip_address(), port_number()}

Retrieves information about a connection.

@@ -541,22 +559,83 @@ The option can be set to the empty list if you do not want the daemon to run any subsystems.

- + pid() | fun(string() = User, ip_address() = PeerAddr) -> pid()}]]>

Defines the read-eval-print loop used when a shell is requested by the client. The default is to use the Erlang shell:

+

See the option exec + for a description of how the daemon execute exec-requests depending on + the shell- and exec-options.

+ + + + +
where: +
exec_spec() = +
fun(Cmd::string()) -> ok_error() +
| fun(Cmd::string(), User::string()) -> ok_error() +
| fun(Cmd::string(), User::string(), ClientAddr::{ip_address(), port_number()}) -> ok_error() + + +

This option changes how the daemon execute exec-requests from clients. The term in ok_error() + is formatted to a string if it is a non-string type. No trailing newline is added in the ok-case but in the + error case.

+

Error texts are returned on channel-type 1 which usually are piped to stderr on e.g Linux systems. + Texts from a successful execution will in similar manner be piped to stdout. The exit-status code + is set to 0 for success and -1 for errors. The exact results presented on the client side depends on the + client. +

+

The option cooperates with the daemon-option shell + in the following way:

+ + 1. If the exec-option is present (the shell-option may or may not be present): + +

The exec-option fun is called with the same number of parameters as the arity of the fun, + and the result is returned to the client. +

+ + + 2. If the exec-option is absent, but a shell-option is present with the default Erlang shell: + +

The default Erlang evaluator is used and the result is returned to the client.

+ + + 3. If the exec-option is absent, but a shell-option is present that is not the default Erlang shell: + +

The exec-request is not evaluated and an error message is returned to the client.

+ + + 4. If neither the exec-option nor the shell-option is present: + +

The default Erlang evaluator is used and the result is returned to the client.

+ + +

If a custom CLI is installed (see the option ssh_cli) + the rules above are replaced by thoose implied by the custom CLI. +

+ +

The exec-option has existed for a long time but has not previously been documented. The old + definition and behaviour are retained but obey the rules 1-4 above if conflicting. + The old and undocumented style should not be used in new programs.

+ - +

Provides your own CLI implementation, that is, a channel callback module that implements a shell and command execution. The shell read-eval-print loop can be customized, using the - option shell. This means less work than implementing - an own CLI channel. If set to no_cli, the CLI channels + option shell. This means less work than implementing + an own CLI channel. If ssh_cli is set to no_cli, the CLI channels + like shell + and exec are disabled and only subsystem channels are allowed.

 -- cgit v1.2.3