-From a8610f7b98ad4b33ab723602863d60d462fa5af2 Mon Sep 17 00:00:00 2001
-Date: Sun, 10 Aug 2025 19:46:01 +0800
-Subject: Don't limit channel window to 500MB
-
-Previously the channel window and increments were limited to 500MB.
-That is incorrect and causes stuck connections if peers advertise
-a large window, then don't send an increment within the first 500MB.
-
-That's seen with SSH.NET https://github.com/sshnet/SSH.NET/issues/1671
----
- src/common-channel.c | 17 ++++++++++-------
- src/sysoptions.h | 3 ---
- 2 files changed, 10 insertions(+), 10 deletions(-)
-
---- a/src/common-channel.c
-+++ b/src/common-channel.c
-@@ -858,17 +858,21 @@ void common_recv_msg_channel_data(struct Channel *channel, int fd,
- void recv_msg_channel_window_adjust() {
-
- struct Channel * channel;
-- unsigned int incr;
-+ unsigned int incr, newwin;
-
- channel = getchannel();
-
- incr = buf_getint(ses.payload);
-- TRACE(("received window increment %d", incr))
-- incr = MIN(incr, TRANS_MAX_WIN_INCR);
-+ TRACE(("received window increment %u", incr))
-
-- channel->transwindow += incr;
-- channel->transwindow = MIN(channel->transwindow, TRANS_MAX_WINDOW);
--
-+ newwin = channel->transwindow + incr;
-+ if (newwin < channel->transwindow) {
-+ /* Integer overflow, clamp it at maximum.
-+ * Behaviour may be unexpected, senders MUST NOT overflow per rfc4254. */
-+ TRACE(("overflow window, prev %u", channel->transwindow));
-+ newwin = 0xffffffff;
-+ }
-+ channel->transwindow = newwin;
- }
-
- /* Increment the incoming data window for a channel, and let the remote
-@@ -906,7 +910,6 @@ void recv_msg_channel_open() {
-
- remotechan = buf_getint(ses.payload);
- transwindow = buf_getint(ses.payload);
-- transwindow = MIN(transwindow, TRANS_MAX_WINDOW);
- transmaxpacket = buf_getint(ses.payload);
- transmaxpacket = MIN(transmaxpacket, TRANS_MAX_PAYLOAD_LEN);
-
---- a/src/sysoptions.h
-+++ b/src/sysoptions.h
-@@ -243,9 +243,6 @@
- #define RECV_MAX_PACKET_LEN (MAX(35000, ((RECV_MAX_PAYLOAD_LEN)+100)))
-
- /* for channel code */
--#define TRANS_MAX_WINDOW 500000000 /* 500MB is sufficient, stopping overflow */
--#define TRANS_MAX_WIN_INCR 500000000 /* overflow prevention */
--
- #define RECV_WINDOWEXTEND (opts.recv_window / 3) /* We send a "window extend" every
- RECV_WINDOWEXTEND bytes */
- #define MAX_RECV_WINDOW (10*1024*1024) /* 10 MB should be enough */
projects / openwrt / openwrt.git / commitdiff