From edf00b752df586b81e8cac3d021b713992e37ac1 Mon Sep 17 00:00:00 2001
From: yuhan6665 <1588741+yuhan6665@users.noreply.github.com>
Date: Sat, 14 Oct 2023 09:41:04 -0400
Subject: [PATCH] crypto/tls: advertise correct ciphers in TLS 1.3 only mode

This change updates the makeClientHello logic to only advertise TLS
1.3 ciphers when tls.Config.MinVersion is set to tls.VersionTLS13
(i.e the client only supports TLS 1.3).  Previously, TLS 1.2 ciphers
would be included in the client hello message.

Fixes #57771

Change-Id: Ife4123037b0a4609578ffffb1cdf1e1d4e0a8df6
GitHub-Last-Rev: 45f4275
GitHub-Pull-Request: #49293
Reviewed-on: https://go-review.googlesource.com/c/go/+/360794
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Run-TryBot: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Marten Seemann <martenseemann@gmail.com>
Auto-Submit: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
---
 handshake_client.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/handshake_client.go b/handshake_client.go
index daed95b..cb56ca5 100644
--- a/handshake_client.go
+++ b/handshake_client.go
@@ -133,6 +133,10 @@ func (c *Conn) makeClientHello() (*clientHelloMsg, *ecdh.PrivateKey, error) {
 
 	var key *ecdh.PrivateKey
 	if hello.supportedVersions[0] == VersionTLS13 {
+		// Reset the list of ciphers when the client only supports TLS 1.3.
+		if len(hello.supportedVersions) == 1 {
+			hello.cipherSuites = nil
+		}
 		if hasAESGCMHardwareSupport {
 			hello.cipherSuites = append(hello.cipherSuites, defaultCipherSuitesTLS13...)
 		} else {