File 0966-ssl-Fix-logical-error-in-flow-control.patch of Package erlang
From 9bac46462fbb748bd3aa631d4eb457594a9e9a8f Mon Sep 17 00:00:00 2001
From: Ingela Anderton Andin <ingela@erlang.org>
Date: Wed, 19 Aug 2020 22:06:20 +0200
Subject: [PATCH] ssl: Fix logical error in flow control
This commit refactors and comments the flow_ctrl function
as well as fixing the logical error reported in ERL-1319.
Probably will not have a noticeable affect but will make
connections more well behaved under some circumstances.
---
lib/ssl/src/tls_connection.erl | 53 ++++++++++++++++++----------------
1 file changed, 28 insertions(+), 25 deletions(-)
diff --git a/lib/ssl/src/tls_connection.erl b/lib/ssl/src/tls_connection.erl
index 9c5662b12f..752083b281 100644
--- a/lib/ssl/src/tls_connection.erl
+++ b/lib/ssl/src/tls_connection.erl
@@ -185,41 +185,44 @@ next_record(_, #state{protocol_buffers = #protocol_buffers{tls_cipher_texts = []
next_record(_, State) ->
{no_record, State}.
-flow_ctrl(#state{user_data_buffer = {_,Size,_},
- socket_options = #socket_options{active = false,
- packet = Packet},
- bytes_to_read = undefined} = State) when ((Packet =/= 0) orelse (Packet =/= raw))
- andalso Size =/= 0 ->
- %% We need more data to complete the packet.
- activate_socket(State);
-flow_ctrl(#state{user_data_buffer = {_,Size,_},
- socket_options = #socket_options{active = false,
- packet = Packet},
- bytes_to_read = BytesToRead} = State) when ((Packet =/= 0) orelse (Packet =/= raw)) ->
- case (Size >= BytesToRead andalso Size =/= 0) of
- true -> %% There is enough data bufferd
- {no_record, State};
- false -> %% We need more data to complete the packet of <BytesToRead> size
- activate_socket(State)
- end;
+%%% bytes_to_read equals the integer Length arg of ssl:recv
+%%% the actual value is only relevant for packet = raw | 0
+%%% bytes_to_read = undefined means no recv call is ongoing
flow_ctrl(#state{user_data_buffer = {_,Size,_},
socket_options = #socket_options{active = false},
bytes_to_read = undefined} = State) when Size =/= 0 ->
- %% Passive mode wait for new recv request
+ %% Passive mode wait for new recv request or socket activation
+ %% that is preserv some tcp back pressure by waiting to activate
+ %% socket
{no_record, State};
+%%%%%%%%%% A packet mode is set and socket is passive %%%%%%%%%%
+flow_ctrl(#state{socket_options = #socket_options{active = false,
+ packet = Packet}} = State)
+ when ((Packet =/= 0) andalso (Packet =/= raw)) ->
+ %% We need more data to complete the packet.
+ activate_socket(State);
+%%%%%%%%% No packet mode set and socket is passive %%%%%%%%%%%%
flow_ctrl(#state{user_data_buffer = {_,Size,_},
socket_options = #socket_options{active = false},
- bytes_to_read = 0} = State) when Size =/= 0 ->
- %% Passive mode no available bytes, get some
+ bytes_to_read = 0} = State) when Size == 0 ->
+ %% Passive mode no available bytes, get some
activate_socket(State);
-flow_ctrl(#state{user_data_buffer = {_,Size,_},
+flow_ctrl(#state{user_data_buffer = {_,Size,_},
socket_options = #socket_options{active = false},
- bytes_to_read = BytesToRead} = State) when (Size >= BytesToRead) andalso
- (BytesToRead > 0) ->
- %% There is enough data bufferd
+ bytes_to_read = 0} = State) when Size =/= 0 ->
+ %% There is data in the buffer to deliver
{no_record, State};
+flow_ctrl(#state{user_data_buffer = {_,Size,_},
+ socket_options = #socket_options{active = false},
+ bytes_to_read = BytesToRead} = State) when (BytesToRead > 0) ->
+ case (Size >= BytesToRead) of
+ true -> %% There is enough data bufferd
+ {no_record, State};
+ false -> %% We need more data to complete the delivery of <BytesToRead> size
+ activate_socket(State)
+ end;
+%%%%%%%%%%% Active mode or more data needed %%%%%%%%%%
flow_ctrl(State) ->
- %% Active mode
activate_socket(State).
--
2.26.2
