www: add the ability to only check for bad resolvers

Author: jedisct1

www/main.go

@@ -2,9 +2,11 @@ package main
 
 import (
 	"flag"
+	"fmt"
 	"log"
 	"os"
 	"os/signal"
+	"sort"
 	"syscall"
 	"time"
 )
@@ -22,6 +24,7 @@ func main() {
 	clearErrors := flag.String("clear-errors", "", "Clear all errors for a resolver (mark as successful) and exit")
 	hideLatency := flag.Bool("hide-latency", false, "Hide latency column in web interface")
 	minReliability := flag.Float64("min-reliability", -1, "Remove resolvers with reliability below this percentage and exit")
+	showFailures := flag.Bool("failures", false, "Print failing resolvers/relays with their error messages and exit")
 	flag.Parse()
 
 	log.SetFlags(log.LstdFlags | log.Lshortfile)
@@ -78,6 +81,23 @@ func main() {
 		return
 	}
 
+	// Handle showing failures
+	if *showFailures {
+		stats, err := db.GetAllStats()
+		if err != nil {
+			log.Fatalf("Failed to get stats: %v", err)
+		}
+		failures := filterFailures(stats)
+		if len(failures) == 0 {
+			log.Println("No failing resolvers/relays")
+			return
+		}
+		for _, s := range failures {
+			fmt.Printf("%s (%s): %s\n", s.Name, s.Type, s.LastError)
+		}
+		return
+	}
+
 	// Auto-rebuild if resolver_stats is empty but test_results has data
 	if err := db.RebuildStatsIfNeeded(); err != nil {
 		log.Printf("Warning: failed to check/rebuild stats: %v", err)
@@ -150,3 +170,28 @@ func main() {
 		}
 	}
 }
+
+// filterFailures returns resolvers where the last test failed.
+// A resolver is considered failing if it has a LastFail time that is
+// more recent than LastSuccess (or if it has never succeeded).
+func filterFailures(stats []ResolverStats) []ResolverStats {
+	var failures []ResolverStats
+	for _, s := range stats {
+		if s.LastError == "" {
+			continue
+		}
+		// Consider it failing if last_fail > last_success
+		if s.LastFail != nil {
+			if s.LastSuccess == nil || s.LastFail.After(*s.LastSuccess) {
+				failures = append(failures, s)
+			}
+		}
+	}
+	sort.Slice(failures, func(i, j int) bool {
+		if failures[i].Type != failures[j].Type {
+			return failures[i].Type < failures[j].Type
+		}
+		return failures[i].Name < failures[j].Name
+	})
+	return failures
+}