feat: logging support in ruleset

README.ja.md

@@ -92,6 +92,11 @@ workers:
 式言語の構文については、[Expr 言語定義](https://expr-lang.org/docs/language-definition)を参照してください。
 
 ```yaml
+# ルールは、"action" または "log" の少なくとも一方が設定されていなければなりません。
+- name: log horny people
+  log: true
+  expr: let sni = string(tls?.req?.sni); sni contains "porn" || sni contains "hentai"
+
 - name: block v2ex http
   action: block
   expr: string(http?.req?.headers?.host) endsWith "v2ex.com"
@@ -104,8 +109,9 @@ workers:
   action: block
   expr: string(quic?.req?.sni) endsWith "v2ex.com"
 
-- name: block shadowsocks
+- name: block and log shadowsocks
   action: block
+  log: true
   expr: fet != nil && fet.yes
 
 - name: block trojan

README.md

@@ -98,6 +98,11 @@ For syntax of the expression language, please refer
 to [Expr Language Definition](https://expr-lang.org/docs/language-definition).
 
 ```yaml
+# A rule must have at least one of "action" or "log" field set.
+- name: log horny people
+  log: true
+  expr: let sni = string(tls?.req?.sni); sni contains "porn" || sni contains "hentai"
+
 - name: block v2ex http
   action: block
   expr: string(http?.req?.headers?.host) endsWith "v2ex.com"
@@ -110,8 +115,9 @@ to [Expr Language Definition](https://expr-lang.org/docs/language-definition).
   action: block
   expr: string(quic?.req?.sni) endsWith "v2ex.com"
 
-- name: block shadowsocks
+- name: block and log shadowsocks
   action: block
+  log: true
   expr: fet != nil && fet.yes
 
 - name: block trojan

README.zh.md

@@ -93,6 +93,11 @@ workers:
 规则的语法请参考 [Expr Language Definition](https://expr-lang.org/docs/language-definition)。
 
 ```yaml
+# 每条规则必须至少包含 action 或 log 中的一个。
+- name: log horny people
+  log: true
+  expr: let sni = string(tls?.req?.sni); sni contains "porn" || sni contains "hentai"
+
 - name: block v2ex http
   action: block
   expr: string(http?.req?.headers?.host) endsWith "v2ex.com"
@@ -105,8 +110,9 @@ workers:
   action: block
   expr: string(quic?.req?.sni) endsWith "v2ex.com"
 
-- name: block shadowsocks
+- name: block and log shadowsocks
   action: block
+  log: true
   expr: fet != nil && fet.yes
 
 - name: block trojan

cmd/root.go

@@ -254,6 +254,7 @@ func runMain(cmd *cobra.Command, args []string) {
 		logger.Fatal("failed to load rules", zap.Error(err))
 	}
 	rsConfig := &ruleset.BuiltinConfig{
+		Logger:          &rulesetLogger{},
 		GeoSiteFilename: config.Ruleset.GeoSite,
 		GeoIpFilename:   config.Ruleset.GeoIp,
 	}
@@ -371,14 +372,6 @@ func (l *engineLogger) UDPStreamAction(info ruleset.StreamInfo, action ruleset.A
 		zap.Bool("noMatch", noMatch))
 }
 
-func (l *engineLogger) MatchError(info ruleset.StreamInfo, err error) {
-	logger.Error("match error",
-		zap.Int64("id", info.ID),
-		zap.String("src", info.SrcString()),
-		zap.String("dst", info.DstString()),
-		zap.Error(err))
-}
-
 func (l *engineLogger) ModifyError(info ruleset.StreamInfo, err error) {
 	logger.Error("modify error",
 		zap.Int64("id", info.ID),
@@ -408,6 +401,26 @@ func (l *engineLogger) AnalyzerErrorf(streamID int64, name string, format string
 		zap.String("msg", fmt.Sprintf(format, args...)))
 }
 
+type rulesetLogger struct{}
+
+func (l *rulesetLogger) Log(info ruleset.StreamInfo, name string) {
+	logger.Info("ruleset log",
+		zap.String("name", name),
+		zap.Int64("id", info.ID),
+		zap.String("src", info.SrcString()),
+		zap.String("dst", info.DstString()),
+		zap.Any("props", info.Props))
+}
+
+func (l *rulesetLogger) MatchError(info ruleset.StreamInfo, name string, err error) {
+	logger.Error("ruleset match error",
+		zap.String("name", name),
+		zap.Int64("id", info.ID),
+		zap.String("src", info.SrcString()),
+		zap.String("dst", info.DstString()),
+		zap.Error(err))
+}
+
 func envOrDefaultString(key, def string) string {
 	if v := os.Getenv(key); v != "" {
 		return v

engine/interface.go

@@ -41,7 +41,6 @@ type Logger interface {
 	UDPStreamPropUpdate(info ruleset.StreamInfo, close bool)
 	UDPStreamAction(info ruleset.StreamInfo, action ruleset.Action, noMatch bool)
 
-	MatchError(info ruleset.StreamInfo, err error)
 	ModifyError(info ruleset.StreamInfo, err error)
 
 	AnalyzerDebugf(streamID int64, name string, format string, args ...interface{})

engine/tcp.go

@@ -148,10 +148,7 @@ func (s *tcpStream) ReassembledSG(sg reassembly.ScatterGather, ac reassembly.Ass
 		s.virgin = false
 		s.logger.TCPStreamPropUpdate(s.info, false)
 		// Match properties against ruleset
-		result, err := s.ruleset.Match(s.info)
-		if err != nil {
-			s.logger.MatchError(s.info, err)
-		}
+		result := s.ruleset.Match(s.info)
 		action := result.Action
 		if action != ruleset.ActionMaybe && action != ruleset.ActionModify {
 			verdict := actionToTCPVerdict(action)

engine/udp.go

@@ -201,10 +201,7 @@ func (s *udpStream) Feed(udp *layers.UDP, rev bool, uc *udpContext) {
 		s.virgin = false
 		s.logger.UDPStreamPropUpdate(s.info, false)
 		// Match properties against ruleset
-		result, err := s.ruleset.Match(s.info)
-		if err != nil {
-			s.logger.MatchError(s.info, err)
-		}
+		result := s.ruleset.Match(s.info)
 		action := result.Action
 		if action == ruleset.ActionModify {
 			// Call the modifier instance
@@ -214,6 +211,7 @@ func (s *udpStream) Feed(udp *layers.UDP, rev bool, uc *udpContext) {
 				s.logger.ModifyError(s.info, errInvalidModifier)
 				action = ruleset.ActionMaybe
 			} else {
+				var err error
 				uc.Packet, err = udpMI.Process(udp.Payload)
 				if err != nil {
 					// Modifier error, fallback to maybe

ruleset/expr.go

@@ -23,6 +23,7 @@ import (
 type ExprRule struct {
 	Name     string        `yaml:"name"`
 	Action   string        `yaml:"action"`
+	Log      bool          `yaml:"log"`
 	Modifier ModifierEntry `yaml:"modifier"`
 	Expr     string        `yaml:"expr"`
 }
@@ -45,7 +46,8 @@ func ExprRulesFromYAML(file string) ([]ExprRule, error) {
 // compiledExprRule is the internal, compiled representation of an expression rule.
 type compiledExprRule struct {
 	Name        string
-	Action      Action
+	Action      *Action // fallthrough if nil
+	Log         bool
 	ModInstance modifier.Instance
 	Program     *vm.Program
 }
@@ -55,32 +57,39 @@ var _ Ruleset = (*exprRuleset)(nil)
 type exprRuleset struct {
 	Rules      []compiledExprRule
 	Ans        []analyzer.Analyzer
+	Logger     Logger
 	GeoMatcher *geo.GeoMatcher
 }
 
 func (r *exprRuleset) Analyzers(info StreamInfo) []analyzer.Analyzer {
 	return r.Ans
 }
 
-func (r *exprRuleset) Match(info StreamInfo) (MatchResult, error) {
+func (r *exprRuleset) Match(info StreamInfo) MatchResult {
 	env := streamInfoToExprEnv(info)
 	for _, rule := range r.Rules {
 		v, err := vm.Run(rule.Program, env)
 		if err != nil {
-			return MatchResult{
-				Action: ActionMaybe,
-			}, fmt.Errorf("rule %q failed to run: %w", rule.Name, err)
+			// Log the error and continue to the next rule.
+			r.Logger.MatchError(info, rule.Name, err)
+			continue
 		}
 		if vBool, ok := v.(bool); ok && vBool {
-			return MatchResult{
-				Action:      rule.Action,
-				ModInstance: rule.ModInstance,
-			}, nil
+			if rule.Log {
+				r.Logger.Log(info, rule.Name)
+			}
+			if rule.Action != nil {
+				return MatchResult{
+					Action:      *rule.Action,
+					ModInstance: rule.ModInstance,
+				}
+			}
 		}
 	}
+	// No match
 	return MatchResult{
 		Action: ActionMaybe,
-	}, nil
+	}
 }
 
 // CompileExprRules compiles a list of expression rules into a ruleset.
@@ -97,11 +106,18 @@ func CompileExprRules(rules []ExprRule, ans []analyzer.Analyzer, mods []modifier
 	}
 	// Compile all rules and build a map of analyzers that are used by the rules.
 	for _, rule := range rules {
-		action, ok := actionStringToAction(rule.Action)
-		if !ok {
-			return nil, fmt.Errorf("rule %q has invalid action %q", rule.Name, rule.Action)
+		if rule.Action == "" && !rule.Log {
+			return nil, fmt.Errorf("rule %q must have at least one of action or log", rule.Name)
 		}
-		visitor := &idVisitor{Identifiers: make(map[string]bool)}
+		var action *Action
+		if rule.Action != "" {
+			a, ok := actionStringToAction(rule.Action)
+			if !ok {
+				return nil, fmt.Errorf("rule %q has invalid action %q", rule.Name, rule.Action)
+			}
+			action = &a
+		}
+		visitor := &idVisitor{Variables: make(map[string]bool), Identifiers: make(map[string]bool)}
 		patcher := &idPatcher{}
 		program, err := expr.Compile(rule.Expr,
 			func(c *conf.Config) {
@@ -118,7 +134,8 @@ func CompileExprRules(rules []ExprRule, ans []analyzer.Analyzer, mods []modifier
 			return nil, fmt.Errorf("rule %q failed to patch expression: %w", rule.Name, patcher.Err)
 		}
 		for name := range visitor.Identifiers {
-			if isBuiltInAnalyzer(name) {
+			// Skip built-in analyzers & user-defined variables
+			if isBuiltInAnalyzer(name) || visitor.Variables[name] {
 				continue
 			}
 			// Check if it's one of the built-in functions, and if so,
@@ -145,9 +162,10 @@ func CompileExprRules(rules []ExprRule, ans []analyzer.Analyzer, mods []modifier
 		cr := compiledExprRule{
 			Name:    rule.Name,
 			Action:  action,
+			Log:     rule.Log,
 			Program: program,
 		}
-		if action == ActionModify {
+		if action != nil && *action == ActionModify {
 			mod, ok := fullModMap[rule.Modifier.Name]
 			if !ok {
 				return nil, fmt.Errorf("rule %q uses unknown modifier %q", rule.Name, rule.Modifier.Name)
@@ -168,6 +186,7 @@ func CompileExprRules(rules []ExprRule, ans []analyzer.Analyzer, mods []modifier
 	return &exprRuleset{
 		Rules:      compiledRules,
 		Ans:        depAns,
+		Logger:     config.Logger,
 		GeoMatcher: geoMatcher,
 	}, nil
 }
@@ -265,11 +284,14 @@ func modifiersToMap(mods []modifier.Modifier) map[string]modifier.Modifier {
 // idVisitor is a visitor that collects all identifiers in an expression.
 // This is for determining which analyzers are used by the expression.
 type idVisitor struct {
+	Variables   map[string]bool
 	Identifiers map[string]bool
 }
 
 func (v *idVisitor) Visit(node *ast.Node) {
-	if idNode, ok := (*node).(*ast.IdentifierNode); ok {
+	if varNode, ok := (*node).(*ast.VariableDeclaratorNode); ok {
+		v.Variables[varNode.Name] = true
+	} else if idNode, ok := (*node).(*ast.IdentifierNode); ok {
 		v.Identifiers[idNode.Value] = true
 	}
 }
@@ -284,6 +306,10 @@ func (p *idPatcher) Visit(node *ast.Node) {
 	switch (*node).(type) {
 	case *ast.CallNode:
 		callNode := (*node).(*ast.CallNode)
+		if callNode.Func == nil {
+			// Ignore invalid call nodes
+			return
+		}
 		switch callNode.Func.Name {
 		case "cidr":
 			cidrStringNode, ok := callNode.Arguments[1].(*ast.StringNode)

ruleset/interface.go

@@ -90,10 +90,17 @@ type Ruleset interface {
 	Analyzers(StreamInfo) []analyzer.Analyzer
 	// Match matches a stream against the ruleset and returns the result.
 	// It must be safe for concurrent use by multiple workers.
-	Match(StreamInfo) (MatchResult, error)
+	Match(StreamInfo) MatchResult
+}
+
+// Logger is the logging interface for the ruleset.
+type Logger interface {
+	Log(info StreamInfo, name string)
+	MatchError(info StreamInfo, name string, err error)
 }
 
 type BuiltinConfig struct {
+	Logger          Logger
 	GeoSiteFilename string
 	GeoIpFilename   string
 }