Rate-limit log sites with shorewall LOGLIMIT

internal/config/config.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
 
 	"gopkg.in/yaml.v3"
@@ -55,7 +56,9 @@ type Settings struct {
 	AddressFamily AddressFamily `yaml:"address_family,omitempty"`
 	IPForwarding  bool          `yaml:"ip_forwarding"`
 	LogLevel      string        `yaml:"log_level"`
-	TableName     string        `yaml:"table_name"`
+	// LogLimit rate-limits every log site, shorewall LOGLIMIT syntax rate/unit[:burst]; unset logs every hit.
+	LogLimit  string `yaml:"log_limit,omitempty"`
+	TableName string `yaml:"table_name"`
 
 	// When true, auto-generate CONTINUE policies for sub-zones to their parent zones.
 	ImplicitContinue bool `yaml:"implicit_continue,omitempty"`
@@ -112,6 +115,8 @@ func (c *Config) applyDefaults() {
 	}
 }
 
+var logLimitRe = regexp.MustCompile(`^[1-9][0-9]*/(sec|second|min|minute|hour|day)(:[1-9][0-9]*)?$`)
+
 var validAddressFamilies = map[AddressFamily]bool{
 	FamilyINET: true, FamilyIP: true, FamilyIP6: true,
 }
@@ -120,6 +125,9 @@ func (c *Config) validateSettings() error {
 	if !validAddressFamilies[c.Settings.AddressFamily] {
 		return fmt.Errorf("unknown address_family %q (use inet, ip, or ip6)", c.Settings.AddressFamily)
 	}
+	if l := c.Settings.LogLimit; l != "" && !logLimitRe.MatchString(l) {
+		return fmt.Errorf("invalid log_limit %q (use rate/{sec|min|hour|day}[:burst]; per-source s:/d: is not supported)", l)
+	}
 	for name, d := range map[string]PolicyAction{
 		"invalid_disposition":   c.Settings.InvalidDisposition,
 		"untracked_disposition": c.Settings.UntrackedDisposition,

internal/config/config_test.go

@@ -1069,3 +1069,15 @@ func TestValidateDispositions(t *testing.T) {
 		checkErr(t, c.Validate(), tc.wantErr)
 	}
 }
+
+func TestValidateLogLimit(t *testing.T) {
+	for v, ok := range map[string]bool{
+		"": true, "1/sec": true, "1/sec:10": true, "30/minute:5": true, "2/hour": true, "1/day:1": true,
+		"s:1/sec:10": false, "d:1/sec": false, "1": false, "1/week": false, "0/sec": false, "1/sec:": false,
+	} {
+		c := &Config{Settings: Settings{AddressFamily: FamilyINET, LogLimit: v}}
+		if err := c.validateSettings(); (err == nil) != ok {
+			t.Errorf("log_limit %q: err = %v, want ok=%v", v, err, ok)
+		}
+	}
+}