From 662f3c7ba50ff8ec13d86171bcfc61fd3da9deed Mon Sep 17 00:00:00 2001 From: Timmo Verlaan Date: Mon, 29 Jan 2018 21:27:22 +0100 Subject: epmd: allow alternative to dns resolving for nodename This makes it possible to create a custom integration with a key-value store for example. The key would then point to the actual address. You would have to write your own epmd module to make use of that feature. --- lib/kernel/doc/src/Makefile | 1 + lib/kernel/doc/src/erl_epmd.xml | 104 +++++++++++++++++++++++++++ lib/kernel/doc/src/ref_man.xml | 1 + lib/kernel/doc/src/specs.xml | 1 + lib/kernel/src/erl_epmd.erl | 64 ++++++++++++++++- lib/kernel/src/inet_tcp_dist.erl | 148 +++++++++++++++++++++++---------------- 6 files changed, 254 insertions(+), 65 deletions(-) create mode 100644 lib/kernel/doc/src/erl_epmd.xml (limited to 'lib/kernel') diff --git a/lib/kernel/doc/src/Makefile b/lib/kernel/doc/src/Makefile index 82869d7b15..29dc73a523 100644 --- a/lib/kernel/doc/src/Makefile +++ b/lib/kernel/doc/src/Makefile @@ -42,6 +42,7 @@ XML_REF3_FILES = application.xml \ disk_log.xml \ erl_boot_server.xml \ erl_ddll.xml \ + erl_epmd.xml \ erl_prim_loader_stub.xml \ erlang_stub.xml \ error_handler.xml \ diff --git a/lib/kernel/doc/src/erl_epmd.xml b/lib/kernel/doc/src/erl_epmd.xml new file mode 100644 index 0000000000..8b076cd2d7 --- /dev/null +++ b/lib/kernel/doc/src/erl_epmd.xml @@ -0,0 +1,104 @@ + + + + +
+ + 20182018 + Ericsson AB. All Rights Reserved. + + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + + + erl_epmd + Timmo Verlaan + 1 + 2018-02-19 + A +
+ erl_epmd + + Erlang interface towards epmd + + +

This module communicates with the EPMD daemon, see epmd. To implement your own epmd module please + see ERTS User's Guide: How to Implement an + Alternative Service Discovery for Erlang Distribution

+ + + + + + Callback for erl_distribution supervisor. + +

This function is invoked as this module is added as a child of the + erl_distribution supervisor.

+ + + + + + + Registers the node with epmd. + +

Registers the node with epmd and tells epmd what port will be + used for the current node. It returns a creation number. This number is + incremented on each register to help with identifying if a node is + reconnecting to epmd.

+ + + + + + + Returns the port number for a given node. + +

Requests the distribution port for the given node of an EPMD + instance. Together with the port it returns a distribution protocol + version which has been 5 since Erlang/OTP R6.

+ + + + + + Returns address and port. + +

Called by the distribution module. Resolves the Host to an IP + address.

+

Another epmd module may return port and distribution protocol version + as well.

+ + + + + + Names of Erlang nodes at a host. + +

Called by net_adm:names/0. + Host defaults to the localhost. Returns the names and associated + port numbers of the Erlang nodes that epmd registered at the + specified host. Returns {error, address} if epmd is not + operational.

+

Example:

+ 
+(arne@dunn)1> erl_epmd:names(localhost).
+{ok,[{"arne",40262}]}
+ + + + + + diff --git a/lib/kernel/doc/src/ref_man.xml b/lib/kernel/doc/src/ref_man.xml index c06914d23d..a633ae4832 100644 --- a/lib/kernel/doc/src/ref_man.xml +++ b/lib/kernel/doc/src/ref_man.xml @@ -38,6 +38,7 @@ + diff --git a/lib/kernel/doc/src/specs.xml b/lib/kernel/doc/src/specs.xml index bcc422930e..b8c25ca53b 100644 --- a/lib/kernel/doc/src/specs.xml +++ b/lib/kernel/doc/src/specs.xml @@ -6,6 +6,7 @@ + diff --git a/lib/kernel/src/erl_epmd.erl b/lib/kernel/src/erl_epmd.erl index f96bc88913..9a0939972d 100644 --- a/lib/kernel/src/erl_epmd.erl +++ b/lib/kernel/src/erl_epmd.erl @@ -29,10 +29,20 @@ -define(port_please_failure2(Term), noop). -endif. +-ifndef(erlang_daemon_port). +-define(erlang_daemon_port, 4369). +-endif. +-ifndef(epmd_dist_high). +-define(epmd_dist_high, 4370). +-endif. +-ifndef(epmd_dist_low). +-define(epmd_dist_low, 4370). +-endif. + %% External exports -export([start/0, start_link/0, stop/0, port_please/2, port_please/3, names/0, names/1, - register_node/2, register_node/3, open/0, open/1, open/2]). + register_node/2, register_node/3, address_please/3, open/0, open/1, open/2]). %% gen_server callbacks -export([init/1, handle_call/3, handle_cast/2, handle_info/2, @@ -53,7 +63,7 @@ start() -> gen_server:start({local, erl_epmd}, ?MODULE, [], []). - +-spec start_link() -> {ok, pid()} | ignore | {error,term()}. start_link() -> gen_server:start_link({local, erl_epmd}, ?MODULE, [], []). @@ -66,9 +76,22 @@ stop() -> %% return {port, P, Version} | noport %% +-spec port_please(Name, Host) -> {ok, Port, Version} | noport when + Name :: string(), + Host :: inet:ip_address(), + Port :: non_neg_integer(), + Version :: non_neg_integer(). + port_please(Node, Host) -> port_please(Node, Host, infinity). +-spec port_please(Name, Host, Timeout) -> {ok, Port, Version} | noport when + Name :: string(), + Host :: inet:ip_address(), + Timeout :: non_neg_integer() | infinity, + Port :: non_neg_integer(), + Version :: non_neg_integer(). + port_please(Node,HostName, Timeout) when is_atom(HostName) -> port_please1(Node,atom_to_list(HostName), Timeout); port_please(Node,HostName, Timeout) when is_list(HostName) -> @@ -92,10 +115,21 @@ port_please1(Node,HostName, Timeout) -> Else end. +-spec names() -> {ok, [{Name, Port}]} | {error, Reason} when + Name :: string(), + Port :: non_neg_integer(), + Reason :: address | file:posix(). + names() -> {ok, H} = inet:gethostname(), names(H). +-spec names(Host) -> {ok, [{Name, Port}]} | {error, Reason} when + Host :: atom() | string() | inet:ip_address(), + Name :: string(), + Port :: non_neg_integer(), + Reason :: address | file:posix(). + names(HostName) when is_atom(HostName); is_list(HostName) -> case inet:gethostbyname(HostName) of {ok,{hostent, _Name, _ , _Af, _Size, [EpmdAddr | _]}} -> @@ -106,9 +140,22 @@ names(HostName) when is_atom(HostName); is_list(HostName) -> names(EpmdAddr) -> get_names(EpmdAddr). +-spec register_node(Name, Port) -> Result when + Name :: string(), + Port :: non_neg_integer(), + Creation :: non_neg_integer(), + Result :: {ok, Creation} | {error, already_registered} | term(). register_node(Name, PortNo) -> - register_node(Name, PortNo, inet). + register_node(Name, PortNo, inet). + +-spec register_node(Name, Port, Driver) -> Result when + Name :: string(), + Port :: non_neg_integer(), + Driver :: inet_tcp | inet6_tcp | inet | inet6, + Creation :: non_neg_integer(), + Result :: {ok, Creation} | {error, already_registered} | term(). + register_node(Name, PortNo, inet_tcp) -> register_node(Name, PortNo, inet); register_node(Name, PortNo, inet6_tcp) -> @@ -116,6 +163,17 @@ register_node(Name, PortNo, inet6_tcp) -> register_node(Name, PortNo, Family) -> gen_server:call(erl_epmd, {register, Name, PortNo, Family}, infinity). +-spec address_please(Name, Host, AddressFamily) -> Success | {error, term()} when + Name :: string(), + Host :: string() | inet:ip_address(), + AddressFamily :: inet | inet6, + Port :: non_neg_integer(), + Version :: non_neg_integer(), + Success :: {ok, inet:ip_address()} | {ok, inet:ip_address(), Port, Version}. + +address_please(_Name, Host, AddressFamily) -> + inet:getaddr(Host, AddressFamily). + %%%---------------------------------------------------------------------- %%% Callback functions from gen_server %%%---------------------------------------------------------------------- diff --git a/lib/kernel/src/inet_tcp_dist.erl b/lib/kernel/src/inet_tcp_dist.erl index e3fdb1bb22..b4b50899f7 100644 --- a/lib/kernel/src/inet_tcp_dist.erl +++ b/lib/kernel/src/inet_tcp_dist.erl @@ -283,73 +283,22 @@ do_setup(Driver, Kernel, Node, Type, MyNode, LongOrShortNames, SetupTime) -> ?trace("~p~n",[{inet_tcp_dist,self(),setup,Node}]), [Name, Address] = splitnode(Driver, Node, LongOrShortNames), AddressFamily = Driver:family(), - case inet:getaddr(Address, AddressFamily) of + ErlEpmd = net_kernel:epmd_module(), + {ARMod, ARFun} = get_address_resolver(ErlEpmd), + Timer = dist_util:start_timer(SetupTime), + case ARMod:ARFun(Name, Address, AddressFamily) of + {ok, Ip, TcpPort, Version} -> + ?trace("address_please(~p) -> version ~p~n", + [Node,Version]), + do_setup_connect(Driver, Kernel, Node, Address, AddressFamily, + Ip, TcpPort, Version, Type, MyNode, Timer); {ok, Ip} -> - Timer = dist_util:start_timer(SetupTime), - ErlEpmd = net_kernel:epmd_module(), case ErlEpmd:port_please(Name, Ip) of {port, TcpPort, Version} -> ?trace("port_please(~p) -> version ~p~n", [Node,Version]), - dist_util:reset_timer(Timer), - case - Driver:connect( - Ip, TcpPort, - connect_options([{active, false}, {packet, 2}])) - of - {ok, Socket} -> - HSData = #hs_data{ - kernel_pid = Kernel, - other_node = Node, - this_node = MyNode, - socket = Socket, - timer = Timer, - this_flags = 0, - other_version = Version, - f_send = fun Driver:send/2, - f_recv = fun Driver:recv/3, - f_setopts_pre_nodeup = - fun(S) -> - inet:setopts - (S, - [{active, false}, - {packet, 4}, - nodelay()]) - end, - f_setopts_post_nodeup = - fun(S) -> - inet:setopts - (S, - [{active, true}, - {deliver, port}, - {packet, 4}, - nodelay()]) - end, - - f_getll = fun inet:getll/1, - f_address = - fun(_,_) -> - #net_address{ - address = {Ip,TcpPort}, - host = Address, - protocol = tcp, - family = AddressFamily} - end, - mf_tick = fun(S) -> ?MODULE:tick(Driver, S) end, - mf_getstat = fun ?MODULE:getstat/1, - request_type = Type, - mf_setopts = fun ?MODULE:setopts/2, - mf_getopts = fun ?MODULE:getopts/2 - }, - dist_util:handshake_we_started(HSData); - _ -> - %% Other Node may have closed since - %% port_please ! - ?trace("other node (~p) " - "closed since port_please.~n", - [Node]), - ?shutdown(Node) - end; + do_setup_connect(Driver, Kernel, Node, Address, AddressFamily, + Ip, TcpPort, Version, Type, MyNode, Timer); _ -> ?trace("port_please (~p) " "failed.~n", [Node]), @@ -361,6 +310,71 @@ do_setup(Driver, Kernel, Node, Type, MyNode, LongOrShortNames, SetupTime) -> ?shutdown(Node) end. +%% +%% Actual setup of connection +%% +do_setup_connect(Driver, Kernel, Node, Address, AddressFamily, + Ip, TcpPort, Version, Type, MyNode, Timer) -> + dist_util:reset_timer(Timer), + case + Driver:connect( + Ip, TcpPort, + connect_options([{active, false}, {packet, 2}])) + of + {ok, Socket} -> + HSData = #hs_data{ + kernel_pid = Kernel, + other_node = Node, + this_node = MyNode, + socket = Socket, + timer = Timer, + this_flags = 0, + other_version = Version, + f_send = fun Driver:send/2, + f_recv = fun Driver:recv/3, + f_setopts_pre_nodeup = + fun(S) -> + inet:setopts + (S, + [{active, false}, + {packet, 4}, + nodelay()]) + end, + f_setopts_post_nodeup = + fun(S) -> + inet:setopts + (S, + [{active, true}, + {deliver, port}, + {packet, 4}, + nodelay()]) + end, + + f_getll = fun inet:getll/1, + f_address = + fun(_,_) -> + #net_address{ + address = {Ip,TcpPort}, + host = Address, + protocol = tcp, + family = AddressFamily} + end, + mf_tick = fun(S) -> ?MODULE:tick(Driver, S) end, + mf_getstat = fun ?MODULE:getstat/1, + request_type = Type, + mf_setopts = fun ?MODULE:setopts/2, + mf_getopts = fun ?MODULE:getopts/2 + }, + dist_util:handshake_we_started(HSData); + _ -> + %% Other Node may have closed since + %% discovery ! + ?trace("other node (~p) " + "closed since discovery (port_please).~n", + [Node]), + ?shutdown(Node) + end. + connect_options(Opts) -> case application:get_env(kernel, inet_dist_connect_options) of {ok,ConnectOpts} -> @@ -429,6 +443,16 @@ get_tcp_address(Driver, Socket) -> family = Driver:family() }. +%% ------------------------------------------------------------ +%% Determine if EPMD module supports address resolving. Default +%% is to use inet:getaddr/2. +%% ------------------------------------------------------------ +get_address_resolver(EpmdModule) -> + case erlang:function_exported(EpmdModule, address_please, 3) of + true -> {EpmdModule, address_please}; + _ -> {inet, getaddr} + end. + %% ------------------------------------------------------------ %% Do only accept new connection attempts from nodes at our %% own LAN, if the check_ip environment parameter is true. -- cgit v1.2.3