From eef613993fdaa330faeaa187c2d2bca6389c4b86 Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Sun, 27 Oct 2024 21:06:56 +0000
Subject: [PATCH] Raise link error when SNI supplied on unsupported link type

Closes #1196
---
 src/core/link.go       | 1 +
 src/core/link_socks.go | 3 +++
 src/core/link_tcp.go   | 3 +++
 src/core/link_unix.go  | 3 +++
 src/core/link_ws.go    | 3 +++
 src/core/link_wss.go   | 3 +++
 6 files changed, 16 insertions(+)

diff --git a/src/core/link.go b/src/core/link.go
index 04fe0266..c2267f24 100644
--- a/src/core/link.go
+++ b/src/core/link.go
@@ -126,6 +126,7 @@ const ErrLinkPinnedKeyInvalid = linkError("pinned public key is invalid")
 const ErrLinkPasswordInvalid = linkError("invalid password supplied")
 const ErrLinkUnrecognisedSchema = linkError("link schema unknown")
 const ErrLinkMaxBackoffInvalid = linkError("max backoff duration invalid")
+const ErrLinkSNINotSupported = linkError("SNI not supported on this link type")
 
 func (l *links) add(u *url.URL, sintf string, linkType linkType) error {
 	var retErr error
diff --git a/src/core/link_socks.go b/src/core/link_socks.go
index b92374d4..0f66661b 100644
--- a/src/core/link_socks.go
+++ b/src/core/link_socks.go
@@ -23,6 +23,9 @@ func (l *links) newLinkSOCKS() *linkSOCKS {
 }
 
 func (l *linkSOCKS) dial(_ context.Context, url *url.URL, info linkInfo, options linkOptions) (net.Conn, error) {
+	if url.Scheme != "sockstls" && options.tlsSNI != "" {
+		return nil, ErrLinkSNINotSupported
+	}
 	var proxyAuth *proxy.Auth
 	if url.User != nil && url.User.Username() != "" {
 		proxyAuth = &proxy.Auth{
diff --git a/src/core/link_tcp.go b/src/core/link_tcp.go
index 4ee50941..38c42def 100644
--- a/src/core/link_tcp.go
+++ b/src/core/link_tcp.go
@@ -67,6 +67,9 @@ func (l *linkTCP) dialersFor(url *url.URL, info linkInfo) ([]*tcpDialer, error)
 }
 
 func (l *linkTCP) dial(ctx context.Context, url *url.URL, info linkInfo, options linkOptions) (net.Conn, error) {
+	if options.tlsSNI != "" {
+		return nil, ErrLinkSNINotSupported
+	}
 	dialers, err := l.dialersFor(url, info)
 	if err != nil {
 		return nil, err
diff --git a/src/core/link_unix.go b/src/core/link_unix.go
index ddbfa0ad..1da6931d 100644
--- a/src/core/link_unix.go
+++ b/src/core/link_unix.go
@@ -31,6 +31,9 @@ func (l *links) newLinkUNIX() *linkUNIX {
 }
 
 func (l *linkUNIX) dial(ctx context.Context, url *url.URL, info linkInfo, options linkOptions) (net.Conn, error) {
+	if options.tlsSNI != "" {
+		return nil, ErrLinkSNINotSupported
+	}
 	addr, err := net.ResolveUnixAddr("unix", url.Path)
 	if err != nil {
 		return nil, err
diff --git a/src/core/link_ws.go b/src/core/link_ws.go
index 0602ed28..59816098 100644
--- a/src/core/link_ws.go
+++ b/src/core/link_ws.go
@@ -87,6 +87,9 @@ func (l *links) newLinkWS() *linkWS {
 }
 
 func (l *linkWS) dial(ctx context.Context, url *url.URL, info linkInfo, options linkOptions) (net.Conn, error) {
+	if options.tlsSNI != "" {
+		return nil, ErrLinkSNINotSupported
+	}
 	wsconn, _, err := websocket.Dial(ctx, url.String(), &websocket.DialOptions{
 		Subprotocols: []string{"ygg-ws"},
 	})
diff --git a/src/core/link_wss.go b/src/core/link_wss.go
index 0bdb4f3a..f09d7955 100644
--- a/src/core/link_wss.go
+++ b/src/core/link_wss.go
@@ -27,6 +27,9 @@ func (l *links) newLinkWSS() *linkWSS {
 }
 
 func (l *linkWSS) dial(ctx context.Context, url *url.URL, info linkInfo, options linkOptions) (net.Conn, error) {
+	if options.tlsSNI != "" {
+		return nil, ErrLinkSNINotSupported
+	}
 	wsconn, _, err := websocket.Dial(ctx, url.String(), &websocket.DialOptions{
 		Subprotocols: []string{"ygg-ws"},
 	})