fix: alert: Check UDPbuffer-size

node/builder.go

@@ -90,6 +90,7 @@ const (
 	// health checks
 	CheckFDLimit
 	CheckFvmConcurrency
+	CheckUDPBufferSize
 	LegacyMarketsEOL
 
 	// libp2p
@@ -169,6 +170,7 @@ func defaults() []Option {
 
 		Override(CheckFDLimit, modules.CheckFdLimit(build.DefaultFDLimit)),
 		Override(CheckFvmConcurrency, modules.CheckFvmConcurrency()),
+		Override(CheckUDPBufferSize, modules.CheckUDPBufferSize(2048*1024)),
 
 		Override(new(system.MemoryConstraints), modules.MemoryConstraints),
 		Override(InitMemoryWatchdog, modules.MemoryWatchdog),

node/modules/alerts.go

@@ -1,8 +1,10 @@
 package modules
 
 import (
+	"net"
 	"os"
 	"strconv"
+	"syscall"
 
 	"github.com/filecoin-project/lotus/journal/alerting"
 	"github.com/filecoin-project/lotus/lib/ulimit"
@@ -35,6 +37,69 @@ func CheckFdLimit(min uint64) func(al *alerting.Alerting) {
 	}
 }
 
+func CheckUDPBufferSize(wanted int) func(al *alerting.Alerting) {
+	return func(al *alerting.Alerting) {
+		conn, err := net.Dial("udp", "localhost:0")
+		if err != nil {
+			alert := al.AddAlertType("process", "udp-buffer-size")
+			al.Raise(alert, map[string]string{
+				"message": "Failed to create UDP connection",
+				"error":   err.Error(),
+			})
+			return
+		}
+		defer func() {
+			if err := conn.Close(); err != nil {
+				log.Warnf("Failed to close connection: %s", err)
+			}
+		}()
+
+		udpConn, ok := conn.(*net.UDPConn)
+		if !ok {
+			alert := al.AddAlertType("process", "udp-buffer-size")
+			al.Raise(alert, map[string]string{
+				"message": "Failed to cast connection to UDPConn",
+			})
+			return
+		}
+
+		file, err := udpConn.File()
+		if err != nil {
+			alert := al.AddAlertType("process", "udp-buffer-size")
+			al.Raise(alert, map[string]string{
+				"message": "Failed to get file descriptor from UDPConn",
+				"error":   err.Error(),
+			})
+			return
+		}
+		defer func() {
+			if err := file.Close(); err != nil {
+				log.Warnf("Failed to close file: %s", err)
+			}
+		}()
+
+		size, err := syscall.GetsockoptInt(int(file.Fd()), syscall.SOL_SOCKET, syscall.SO_RCVBUF)
+		if err != nil {
+			alert := al.AddAlertType("process", "udp-buffer-size")
+			al.Raise(alert, map[string]string{
+				"message": "Failed to get UDP buffer size",
+				"error":   err.Error(),
+			})
+			return
+		}
+
+		if size < wanted {
+			alert := al.AddAlertType("process", "udp-buffer-size")
+			al.Raise(alert, map[string]interface{}{
+				"message":      "UDP buffer size is low",
+				"current_size": size,
+				"wanted_size":  wanted,
+				"help":         "See https://github.com/quic-go/quic-go/wiki/UDP-Buffer-Sizes for details.",
+			})
+		}
+	}
+}
+
 func LegacyMarketsEOL(al *alerting.Alerting) {
 	// Add alert if lotus-miner legacy markets subsystem is still in use
 	alert := al.AddAlertType("system", "EOL")