From 62694cb43d403852034b5084dcdcb2cfd66cc9b9 Mon Sep 17 00:00:00 2001
From: rustdesk <info@rustdesk.com>
Date: Wed, 26 Aug 2026 22:24:00 +0800
Subject: [PATCH] webrtc: correct the RTT variance floor to dcsctp's scaling

The earlier commit took dcsctp's min_rtt_variance = 220 as a raw floor under
rttvar. dcsctp divides the option by kHeuristicVarianceAdjustment = 8.0 first,
a historical accident it kept because downstream users had measured good
values with it, so the intended floor is 27.5ms of variance contributing 110ms
to RTO. Flooring at 220 contributed 880ms instead, which on a 50ms path left
RTO within 7% of the 1000ms default this change exists to escape.

The fork also now records why T1/T2 share T3's RTO manager here, unlike
dcsctp's separate control timers: RTO_INITIAL is the T3 value for the first
DATA chunk, since no RTT sample exists before the first SACK.
---
 Cargo.lock | 4 ++--
 Cargo.toml | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 77a32b0be..c0a6ede69 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -9706,7 +9706,7 @@ dependencies = [
 [[package]]
 name = "webrtc-sctp"
 version = "0.12.0"
-source = "git+https://github.com/rustdesk-org/webrtc?rev=56d097c54f9ea1e48c0dfbeb6ce7e66d2e66e833#56d097c54f9ea1e48c0dfbeb6ce7e66d2e66e833"
+source = "git+https://github.com/rustdesk-org/webrtc?rev=0a84ba37fbca940b82f230fb469d1b3a3172abf6#0a84ba37fbca940b82f230fb469d1b3a3172abf6"
 dependencies = [
  "arc-swap",
  "async-trait",
@@ -9746,7 +9746,7 @@ dependencies = [
 [[package]]
 name = "webrtc-util"
 version = "0.11.0"
-source = "git+https://github.com/rustdesk-org/webrtc?rev=56d097c54f9ea1e48c0dfbeb6ce7e66d2e66e833#56d097c54f9ea1e48c0dfbeb6ce7e66d2e66e833"
+source = "git+https://github.com/rustdesk-org/webrtc?rev=0a84ba37fbca940b82f230fb469d1b3a3172abf6#0a84ba37fbca940b82f230fb469d1b3a3172abf6"
 dependencies = [
  "async-trait",
  "bitflags 1.3.2",
diff --git a/Cargo.toml b/Cargo.toml
index 3b874845d..037b973b7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -222,8 +222,8 @@ libxdo-sys = { path = "libs/libxdo-sys-stub" }
 # and fast retransmit cannot cover a request/response exchange; INITIAL_MTU 1228 also fragments on
 # IPv6. The fork commit carries the arithmetic.
 # Pinned by rev, not branch: a fork branch can be rewritten out from under the lockfile.
-webrtc-util = { git = "https://github.com/rustdesk-org/webrtc", rev = "56d097c54f9ea1e48c0dfbeb6ce7e66d2e66e833" }
-webrtc-sctp = { git = "https://github.com/rustdesk-org/webrtc", rev = "56d097c54f9ea1e48c0dfbeb6ce7e66d2e66e833" }
+webrtc-util = { git = "https://github.com/rustdesk-org/webrtc", rev = "0a84ba37fbca940b82f230fb469d1b3a3172abf6" }
+webrtc-sctp = { git = "https://github.com/rustdesk-org/webrtc", rev = "0a84ba37fbca940b82f230fb469d1b3a3172abf6" }
 
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