Add canonical peer status logging with sampling (#269)

* Add canonical peer status log

* Use %q formatting

* Use underscore for consistency

canonicallog/canonicallog.go

@@ -1,7 +1,10 @@
 package canonicallog
 
 import (
+	"fmt"
+	"math/rand"
 	"net"
+	"strings"
 
 	logging "github.com/ipfs/go-log/v2"
 	"github.com/libp2p/go-libp2p-core/peer"
@@ -15,7 +18,7 @@ var log = logging.WithSkip(logging.Logger("canonical-log"), 1)
 // Protocols should use this to identify a misbehaving peer to allow the end
 // user to easily identify these nodes across protocols and libp2p.
 func LogMisbehavingPeer(p peer.ID, peerAddr multiaddr.Multiaddr, component string, err error, msg string) {
-	log.Warnf("CANONICAL_MISBEHAVING_PEER: peer=%s addr=%s component=%s err=%v msg=%s", p, peerAddr.String(), component, err, msg)
+	log.Warnf("CANONICAL_MISBEHAVING_PEER: peer=%s addr=%s component=%s err=%q msg=%q", p, peerAddr.String(), component, err, msg)
 }
 
 // LogMisbehavingPeerNetAddr is the canonical way to log a misbehaving peer.
@@ -24,9 +27,30 @@ func LogMisbehavingPeer(p peer.ID, peerAddr multiaddr.Multiaddr, component strin
 func LogMisbehavingPeerNetAddr(p peer.ID, peerAddr net.Addr, component string, originalErr error, msg string) {
 	ma, err := manet.FromNetAddr(peerAddr)
 	if err != nil {
-		log.Warnf("CANONICAL_MISBEHAVING_PEER: peer=%s netAddr=%s component=%s err=%v msg=%s", p, peerAddr.String(), component, originalErr, msg)
+		log.Warnf("CANONICAL_MISBEHAVING_PEER: peer=%s net_addr=%s component=%s err=%q msg=%q", p, peerAddr.String(), component, originalErr, msg)
 		return
 	}
 
-	log.Warnf("CANONICAL_MISBEHAVING_PEER: peer=%s addr=%s component=%s err=%v msg=%s", p, ma, component, originalErr, msg)
+	LogMisbehavingPeer(p, ma, component, originalErr, msg)
+}
+
+// LogPeerStatus logs any useful information about a peer. It takes in a sample
+// rate and will only log one in every sampleRate messages (randomly). This is
+// useful in surfacing events that are normal in isolation, but may be abnormal
+// in large quantities. For example, a successful connection from an IP address
+// is normal. 10,000 connections from that same IP address is not normal. libp2p
+// itself does nothing besides emitting this log. Hook this up to another tool
+// like fail2ban to action on the log.
+func LogPeerStatus(sampleRate int, p peer.ID, peerAddr multiaddr.Multiaddr, keyVals ...string) {
+	if rand.Intn(sampleRate) == 0 {
+		keyValsStr := strings.Builder{}
+		for i, kOrV := range keyVals {
+			if i%2 == 0 {
+				fmt.Fprintf(&keyValsStr, " %v=", kOrV)
+			} else {
+				fmt.Fprintf(&keyValsStr, "%q", kOrV)
+			}
+		}
+		log.Infof("CANONICAL_PEER_STATUS: peer=%s addr=%s sample_rate=%v%s", p, peerAddr.String(), sampleRate, keyValsStr.String())
+	}
 }

canonicallog/canonicallog_test.go

@@ -5,13 +5,21 @@ import (
 	"net"
 	"testing"
 
+	logging "github.com/ipfs/go-log/v2"
 	"github.com/libp2p/go-libp2p-core/test"
 	"github.com/multiformats/go-multiaddr"
 )
 
 func TestLogs(t *testing.T) {
+	err := logging.SetLogLevel("canonical-log", "info")
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	LogMisbehavingPeer(test.RandPeerIDFatal(t), multiaddr.StringCast("/ip4/1.2.3.4"), "somecomponent", fmt.Errorf("something"), "hi")
 
 	netAddr := &net.TCPAddr{IP: net.ParseIP("127.0.0.1"), Port: 80}
-	LogMisbehavingPeerNetAddr(test.RandPeerIDFatal(t), netAddr, "somecomponent", fmt.Errorf("something"), "hi")
+	LogMisbehavingPeerNetAddr(test.RandPeerIDFatal(t), netAddr, "somecomponent", fmt.Errorf("something"), "hello \"world\"")
+
+	LogPeerStatus(1, test.RandPeerIDFatal(t), multiaddr.StringCast("/ip4/1.2.3.4"), "extra", "info")
 }