Wireguard inbound: Fix context sharing problem (#4988)

* Try fix Wireguard inbound context sharing problem

* Shallow copy inbound and content

* Fix context passing

* Add notes for source address

common/session/context.go

@@ -16,15 +16,15 @@ const (
 	inboundSessionKey         ctx.SessionKey = 1
 	outboundSessionKey        ctx.SessionKey = 2
 	contentSessionKey         ctx.SessionKey = 3
-	muxPreferredSessionKey    ctx.SessionKey = 4
-	sockoptSessionKey         ctx.SessionKey = 5
-	trackedConnectionErrorKey ctx.SessionKey = 6
-	dispatcherKey             ctx.SessionKey = 7
-	timeoutOnlyKey            ctx.SessionKey = 8
-	allowedNetworkKey         ctx.SessionKey = 9
-	handlerSessionKey         ctx.SessionKey = 10
-	mitmAlpn11Key             ctx.SessionKey = 11
-	mitmServerNameKey         ctx.SessionKey = 12
+	muxPreferredSessionKey    ctx.SessionKey = 4 // unused
+	sockoptSessionKey         ctx.SessionKey = 5 // used by dokodemo to only receive sockopt.Mark
+	trackedConnectionErrorKey ctx.SessionKey = 6 // used by observer to get outbound error
+	dispatcherKey             ctx.SessionKey = 7 // used by ss2022 inbounds to get dispatcher
+	timeoutOnlyKey            ctx.SessionKey = 8 // mux context's child contexts to only cancel when its own traffic times out
+	allowedNetworkKey         ctx.SessionKey = 9 // muxcool server control incoming request tcp/udp
+	handlerSessionKey         ctx.SessionKey = 10 // unused
+	mitmAlpn11Key             ctx.SessionKey = 11 // used by TLS dialer
+	mitmServerNameKey         ctx.SessionKey = 12 // used by TLS dialer
 )
 
 func ContextWithInbound(ctx context.Context, inbound *Inbound) context.Context {
@@ -42,18 +42,8 @@ func ContextWithOutbounds(ctx context.Context, outbounds []*Outbound) context.Co
 	return context.WithValue(ctx, outboundSessionKey, outbounds)
 }
 
-func ContextCloneOutboundsAndContent(ctx context.Context) context.Context {
-	outbounds := OutboundsFromContext(ctx)
-	newOutbounds := make([]*Outbound, len(outbounds))
-	for i, ob := range outbounds {
-		if ob == nil {
-			continue
-		}
-
-		// copy outbound by value
-		v := *ob
-		newOutbounds[i] = &v
-	}
+func SubContextFromMuxInbound(ctx context.Context) context.Context {
+	newOutbounds := []*Outbound{{}}
 
 	content := ContentFromContext(ctx)
 	newContent := Content{}

common/session/session.go

@@ -48,9 +48,9 @@ type Inbound struct {
 	User *protocol.MemoryUser
 	// VlessRoute is the user-sent VLESS UUID's last byte.
 	VlessRoute net.Port
-	// Conn is actually internet.Connection. May be nil.
+	// Used by splice copy. Conn is actually internet.Connection. May be nil.
 	Conn net.Conn
-	// Timer of the inbound buf copier. May be nil.
+	// Used by splice copy. Timer of the inbound buf copier. May be nil.
 	Timer *signal.ActivityTimer
 	// CanSpliceCopy is a property for this connection
 	// 1 = can, 2 = after processing protocol info should be able to, 3 = cannot
@@ -69,31 +69,33 @@ type Outbound struct {
 	Tag string
 	// Name of the outbound proxy that handles the connection.
 	Name string
-	// Conn is actually internet.Connection. May be nil. It is currently nil for outbound with proxySettings
+	// Unused. Conn is actually internet.Connection. May be nil. It is currently nil for outbound with proxySettings
 	Conn net.Conn
 	// CanSpliceCopy is a property for this connection
 	// 1 = can, 2 = after processing protocol info should be able to, 3 = cannot
 	CanSpliceCopy int
 }
 
-// SniffingRequest controls the behavior of content sniffing.
+// SniffingRequest controls the behavior of content sniffing. They are from inbound config. Read-only
 type SniffingRequest struct {
-	ExcludeForDomain               []string // read-only once set
-	OverrideDestinationForProtocol []string // read-only once set
+	ExcludeForDomain               []string
+	OverrideDestinationForProtocol []string
 	Enabled                        bool
 	MetadataOnly                   bool
 	RouteOnly                      bool
 }
 
-// Content is the metadata of the connection content.
+// Content is the metadata of the connection content. Mainly used for routing.
 type Content struct {
 	// Protocol of current content.
 	Protocol string
 
 	SniffingRequest SniffingRequest
 
+	// HTTP traffic sniffed headers
 	Attributes map[string]string
 
+	// SkipDNSResolve is set from DNS module. the DOH remote server maybe a domain name, this prevents cycle resolving dead loop
 	SkipDNSResolve bool
 }