File 4472-ssh-improve-docs-of-ssh-keep-alive.patch of Package erlang
From 51e2907d2610d947586ef0a6e9e1c18ebb8d706f Mon Sep 17 00:00:00 2001
From: Alexandre Rodrigues <alexandrejbr@live.com>
Date: Wed, 13 Aug 2025 15:55:12 +0200
Subject: [PATCH 02/20] ssh: improve docs of ssh keep alive
---
lib/ssh/src/ssh.hrl | 21 +++++++++++++++++++++
lib/ssh/src/ssh_connection_handler.erl | 14 ++++++++------
2 files changed, 29 insertions(+), 6 deletions(-)
diff --git a/lib/ssh/src/ssh.hrl b/lib/ssh/src/ssh.hrl
index 7b9c292d63..be99ba3d2a 100644
--- a/lib/ssh/src/ssh.hrl
+++ b/lib/ssh/src/ssh.hrl
@@ -378,6 +378,7 @@ further explained below.
| auth_methods_common_option()
| inet_common_option()
| fd_common_option()
+ | alive_common_option()
.
-define(COMMON_OPTION, common_option()).
@@ -538,6 +539,7 @@ protocol).
-type inet_common_option() :: {inet, inet | inet6} .
-type fd_common_option() :: {fd, gen_tcp:socket()} .
+-type alive_common_option() :: {AliveCountMax::pos_integer(), AliveInterval::timeout()}.
-type opaque_common_options() ::
{transport, {atom(),atom(),atom()} }
diff --git a/lib/ssh/src/ssh_connection_handler.erl b/lib/ssh/src/ssh_connection_handler.erl
index 855783b7c7..614adfad68 100644
--- a/lib/ssh/src/ssh_connection_handler.erl
+++ b/lib/ssh/src/ssh_connection_handler.erl
@@ -2187,13 +2187,11 @@ update_inet_buffers(Socket) ->
%%%----------------------------------------------------------------
%%% Keep-alive
-%% @doc Reset the last_alive timer on #data{ssh_params=#ssh{}} record
-%% @private
+%% Reset the last_alive timer on #data{ssh_params=#ssh{}} record
reset_alive(D = #data{ssh_params = Ssh}) ->
D#data{ssh_params = reset_alive_ssh_params(Ssh)}.
-%% @doc Update #data.ssh_params last_alive on an incoming SSH message
-%% @private
+%% Update #data.ssh_params last_alive on an incoming SSH message
reset_alive_ssh_params(SSH = #ssh{alive_interval = AliveInterval})
when is_integer(AliveInterval) ->
Now = erlang:monotonic_time(milli_seconds),
@@ -2202,7 +2200,7 @@ reset_alive_ssh_params(SSH = #ssh{alive_interval = AliveInterval})
reset_alive_ssh_params(SSH) ->
SSH.
-%% @doc Returns a pair of {TriggerFlag, Actions} where trigger flag indicates that
+%% Returns a pair of {TriggerFlag, Actions} where trigger flag indicates that
%% the timeout has been triggered already and it is time to disconnect, and
%% Actions may contain a new timeout action to check for the timeout again.
get_next_alive_timeout(#ssh{alive_interval = AliveInterval,
@@ -2227,7 +2225,6 @@ triggered_alive(StateName, D0 = #data{},
Details = "Alive timeout triggered",
{Shutdown, D} = ?send_disconnect(?SSH_DISCONNECT_CONNECTION_LOST, Details, StateName, D0),
{stop, Shutdown, D};
-
triggered_alive(_StateName, Data, _Ssh = #ssh{alive_sent_probes = SentProbes}, Actions) ->
Data1 = send_msg(?KEEP_ALIVE_REQUEST, Data),
Ssh = Data1#data.ssh_params,
@@ -2237,6 +2234,11 @@ triggered_alive(_StateName, Data, _Ssh = #ssh{alive_sent_probes = SentProbes}, A
last_alive_at = Now},
{keep_state, Data1#data{ssh_params = Ssh1}, Actions}.
+%% Keep-alive messages can't be sent during renegotiation, but since this
+%% feature acts as a keep-alive and a timeout, an equivalent timeout is
+%% established for the renegotiation procedure if alive is enabled.
+%% For simplicity the timeout value is derived from alive_interval and
+%% alive_count.
renegotiation_alive_timeout(#ssh{alive_interval = infinity}) ->
infinity;
renegotiation_alive_timeout(#ssh{alive_interval = Interval, alive_count = Count}) ->
--
2.51.0
