From 9b46209f1bf2ea30d91a1d20ccf9a908a5be5632 Mon Sep 17 00:00:00 2001
From: Siyuan <siyuan@buildjet.com>
Date: Mon, 13 Oct 2025 16:17:35 +0000
Subject: [PATCH] fix: clean up udhcpc processes

---
 network.go                    |  1 +
 pkg/nmlite/jetdhcpc/legacy.go | 15 +++++++++++----
 pkg/nmlite/manager.go         | 27 +++++++++++++++++++++++++++
 3 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/network.go b/network.go
index 719fdd0c..8a7c2761 100644
--- a/network.go
+++ b/network.go
@@ -151,6 +151,7 @@ func initNetwork() error {
 	if err := nm.AddInterface(NetIfName, nc); err != nil {
 		return fmt.Errorf("failed to add interface: %w", err)
 	}
+	_ = nm.CleanUpLegacyDHCPClients()
 
 	networkManager = nm
 
diff --git a/pkg/nmlite/jetdhcpc/legacy.go b/pkg/nmlite/jetdhcpc/legacy.go
index b8ee4c0b..6fa2ddf9 100644
--- a/pkg/nmlite/jetdhcpc/legacy.go
+++ b/pkg/nmlite/jetdhcpc/legacy.go
@@ -8,6 +8,8 @@ import (
 	"strconv"
 	"strings"
 	"syscall"
+
+	"github.com/rs/zerolog"
 )
 
 func readFileNoStat(filename string) ([]byte, error) {
@@ -36,7 +38,8 @@ func toCmdline(path string) ([]string, error) {
 	return strings.Split(string(bytes.TrimRight(data, "\x00")), "\x00"), nil
 }
 
-func (c *Client) killUdhcpc() error {
+// KillUdhcpC kills all udhcpc processes
+func KillUdhcpC(l *zerolog.Logger) error {
 	// read procfs for udhcpc processes
 	// we do not use procfs.AllProcs() because we want to avoid the overhead of reading the entire procfs
 	processes, err := os.ReadDir("/proc")
@@ -76,11 +79,11 @@ func (c *Client) killUdhcpc() error {
 	}
 
 	if len(matchedPids) == 0 {
-		c.l.Info().Msg("no udhcpc processes found")
+		l.Info().Msg("no udhcpc processes found")
 		return nil
 	}
 
-	c.l.Info().Ints("pids", matchedPids).Msg("found udhcpc processes, terminating")
+	l.Info().Ints("pids", matchedPids).Msg("found udhcpc processes, terminating")
 
 	for _, pid := range matchedPids {
 		err := syscall.Kill(pid, syscall.SIGTERM)
@@ -88,8 +91,12 @@ func (c *Client) killUdhcpc() error {
 			return err
 		}
 
-		c.l.Info().Int("pid", pid).Msg("terminated udhcpc process")
+		l.Info().Int("pid", pid).Msg("terminated udhcpc process")
 	}
 
 	return nil
 }
+
+func (c *Client) killUdhcpc() error {
+	return KillUdhcpC(c.l)
+}
diff --git a/pkg/nmlite/manager.go b/pkg/nmlite/manager.go
index d8a0ddd8..03496d9e 100644
--- a/pkg/nmlite/manager.go
+++ b/pkg/nmlite/manager.go
@@ -11,6 +11,7 @@ import (
 
 	"github.com/jetkvm/kvm/internal/logging"
 	"github.com/jetkvm/kvm/internal/network/types"
+	"github.com/jetkvm/kvm/pkg/nmlite/jetdhcpc"
 	"github.com/jetkvm/kvm/pkg/nmlite/link"
 	"github.com/rs/zerolog"
 )
@@ -214,6 +215,32 @@ func (nm *NetworkManager) SetOnDHCPLeaseChange(callback func(iface string, lease
 	nm.onDHCPLeaseChange = callback
 }
 
+func (nm *NetworkManager) shouldKillLegacyDHCPClients() bool {
+	nm.mu.RLock()
+	defer nm.mu.RUnlock()
+
+	// TODO: remove it when we need to support multiple interfaces
+	for _, im := range nm.interfaces {
+		if im.dhcpClient.clientType != "udhcpc" {
+			return true
+		}
+
+		if im.config.IPv4Mode.String != "dhcp" {
+			return true
+		}
+	}
+	return false
+}
+
+// CleanUpLegacyDHCPClients cleans up legacy DHCP clients
+func (nm *NetworkManager) CleanUpLegacyDHCPClients() error {
+	shouldKill := nm.shouldKillLegacyDHCPClients()
+	if shouldKill {
+		return jetdhcpc.KillUdhcpC(nm.logger)
+	}
+	return nil
+}
+
 // Stop stops the network manager and all managed interfaces
 func (nm *NetworkManager) Stop() error {
 	nm.mu.Lock()