From f974de115cbe4dea596174fe01d04072fff32f21 Mon Sep 17 00:00:00 2001
From: Hector <dev@hsmith.org>
Date: Thu, 14 Oct 2021 21:40:50 +0100
Subject: [PATCH] add new metrics for find time and max retry

---
 src/collector/f2b/socket.go  | 28 ++++++++++++++++++++++++++++
 src/socket/fail2banSocket.go | 36 ++++++++++++++++++++++++++----------
 src/socket/protocol.go       |  2 ++
 3 files changed, 56 insertions(+), 10 deletions(-)

diff --git a/src/collector/f2b/socket.go b/src/collector/f2b/socket.go
index 40764b3..7dadd95 100644
--- a/src/collector/f2b/socket.go
+++ b/src/collector/f2b/socket.go
@@ -51,6 +51,16 @@ var (
 		"How long an IP is banned for in this jail (in seconds)",
 		[]string{"jail"}, nil,
 	)
+	metricJailFindTime = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "config", "jail_find_time"),
+		"How far back will the filter look for failures in this jail (in seconds)",
+		[]string{"jail"}, nil,
+	)
+	metricJailMaxRetry = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "config", "jail_max_retries"),
+		"The number of failures allowed until the IP is banned by this jail",
+		[]string{"jail"}, nil,
+	)
 	metricVersionInfo = prometheus.NewDesc(
 		prometheus.BuildFQName(namespace, "", "version"),
 		"Version of the exporter and fail2ban server",
@@ -139,6 +149,24 @@ func (c *Collector) collectJailConfigMetrics(ch chan<- prometheus.Metric, s *soc
 			metricJailBanTime, prometheus.GaugeValue, float64(banTime), jail,
 		)
 	}
+	findTime, err := s.GetJailFindTime(jail)
+	if err != nil {
+		c.socketRequestErrorCount++
+		log.Printf("failed to get find time for jail %s: %v", jail, err)
+	} else {
+		ch <- prometheus.MustNewConstMetric(
+			metricJailFindTime, prometheus.GaugeValue, float64(findTime), jail,
+		)
+	}
+	maxRetry, err := s.GetJailMaxRetries(jail)
+	if err != nil {
+		c.socketRequestErrorCount++
+		log.Printf("failed to get max retries for jail %s: %v", jail, err)
+	} else {
+		ch <- prometheus.MustNewConstMetric(
+			metricJailMaxRetry, prometheus.GaugeValue, float64(maxRetry), jail,
+		)
+	}
 }
 
 func (c *Collector) collectVersionMetric(ch chan<- prometheus.Metric, s *socket.Fail2BanSocket) {
diff --git a/src/socket/fail2banSocket.go b/src/socket/fail2banSocket.go
index d51321a..0288dd9 100644
--- a/src/socket/fail2banSocket.go
+++ b/src/socket/fail2banSocket.go
@@ -120,17 +120,17 @@ func (s *Fail2BanSocket) GetJailStats(jail string) (JailStats, error) {
 
 func (s *Fail2BanSocket) GetJailBanTime(jail string) (int, error) {
 	command := fmt.Sprintf(banTimeCommandFmt, jail)
-	response, err := s.sendCommand(strings.Split(command, " "))
-	if err != nil {
-		return -1, err
-	}
+	return s.sendSimpleIntCommand(command)
+}
 
-	if lvl1, ok := response.(*types.Tuple); ok {
-		if banTime, ok := lvl1.Get(1).(int); ok {
-			return banTime, nil
-		}
-	}
-	return -1, newBadFormatError(command, response)
+func (s *Fail2BanSocket) GetJailFindTime(jail string) (int, error) {
+	command := fmt.Sprintf(findTimeCommandFmt, jail)
+	return s.sendSimpleIntCommand(command)
+}
+
+func (s *Fail2BanSocket) GetJailMaxRetries(jail string) (int, error) {
+	command := fmt.Sprintf(maxRetriesCommandFmt, jail)
+	return s.sendSimpleIntCommand(command)
 }
 
 func (s *Fail2BanSocket) GetServerVersion() (string, error) {
@@ -147,6 +147,22 @@ func (s *Fail2BanSocket) GetServerVersion() (string, error) {
 	return "", newBadFormatError(versionCommand, response)
 }
 
+// sendSimpleIntCommand sends a command to the fail2ban socket and parses the response to extract an int.
+// This command assumes that the response data is in the format of `(d, d)` where `d` is a number.
+func (s *Fail2BanSocket) sendSimpleIntCommand(command string) (int, error) {
+	response, err := s.sendCommand(strings.Split(command, " "))
+	if err != nil {
+		return -1, err
+	}
+
+	if lvl1, ok := response.(*types.Tuple); ok {
+		if banTime, ok := lvl1.Get(1).(int); ok {
+			return banTime, nil
+		}
+	}
+	return -1, newBadFormatError(command, response)
+}
+
 func newBadFormatError(command string, data interface{}) error {
 	return fmt.Errorf("(%s) unexpected response format - cannot parse: %v", command, data)
 }
diff --git a/src/socket/protocol.go b/src/socket/protocol.go
index 68ca5a8..54d3b6e 100644
--- a/src/socket/protocol.go
+++ b/src/socket/protocol.go
@@ -13,6 +13,8 @@ const (
 	statusCommand        = "status"
 	versionCommand       = "version"
 	banTimeCommandFmt    = "get %s bantime"
+	findTimeCommandFmt   = "get %s findtime"
+	maxRetriesCommandFmt = "get %s maxretry"
 	socketReadBufferSize = 1024
 )