From 344d343431c014727dcb3abe9eba02e3d7f3e6a9 Mon Sep 17 00:00:00 2001
From: Bruce Ma <brucema19901024@gmail.com>
Date: Sat, 18 May 2019 13:58:33 +0800
Subject: [PATCH] bandwidth: get bandwidth interface in host ns through
 container interface

Signed-off-by: Bruce Ma <brucema19901024@gmail.com>
---
 plugins/meta/bandwidth/main.go | 49 ++++++++++++++++++++++++++--------
 1 file changed, 38 insertions(+), 11 deletions(-)

diff --git a/plugins/meta/bandwidth/main.go b/plugins/meta/bandwidth/main.go
index 6d800589..d967c932 100644
--- a/plugins/meta/bandwidth/main.go
+++ b/plugins/meta/bandwidth/main.go
@@ -17,7 +17,6 @@ package main
 import (
 	"crypto/sha1"
 	"encoding/json"
-	"errors"
 	"fmt"
 
 	"github.com/vishvananda/netlink"
@@ -28,6 +27,7 @@ import (
 	"github.com/containernetworking/cni/pkg/version"
 
 	"github.com/containernetworking/plugins/pkg/ip"
+	"github.com/containernetworking/plugins/pkg/ns"
 	bv "github.com/containernetworking/plugins/pkg/utils/buildversion"
 )
 
@@ -130,21 +130,35 @@ func getMTU(deviceName string) (int, error) {
 	return link.Attrs().MTU, nil
 }
 
-func getHostInterface(interfaces []*current.Interface) (*current.Interface, error) {
+// get the veth peer of container interface in host namespace
+func getHostInterface(interfaces []*current.Interface, containerIfName string, netns ns.NetNS) (*current.Interface, error) {
 	if len(interfaces) == 0 {
-		return nil, errors.New("no interfaces provided")
+		return nil, fmt.Errorf("no interfaces provided")
 	}
 
+	// get veth peer index of container interface
+	var peerIndex int
 	var err error
+	_ = netns.Do(func(_ ns.NetNS) error {
+		_, peerIndex, err = ip.GetVethPeerIfindex(containerIfName)
+		return nil
+	})
+	if peerIndex <= 0 {
+		return nil, fmt.Errorf("container interface %s has no veth peer: %v", containerIfName, err)
+	}
+
+	// find host interface by index
+	link, err := netlink.LinkByIndex(peerIndex)
+	if err != nil {
+		return nil, fmt.Errorf("veth peer with index %d is not in host ns", peerIndex)
+	}
 	for _, iface := range interfaces {
-		if iface.Sandbox == "" { // host interface
-			_, _, err = ip.GetVethPeerIfindex(iface.Name)
-			if err == nil {
-				return iface, err
-			}
+		if iface.Sandbox == "" && iface.Name == link.Attrs().Name {
+			return iface, nil
 		}
 	}
-	return nil, errors.New(fmt.Sprintf("no host interface found. last error: %s", err))
+
+	return nil, fmt.Errorf("no veth peer of container interface found in host ns")
 }
 
 func cmdAdd(args *skel.CmdArgs) error {
@@ -166,7 +180,14 @@ func cmdAdd(args *skel.CmdArgs) error {
 	if err != nil {
 		return fmt.Errorf("could not convert result to current version: %v", err)
 	}
-	hostInterface, err := getHostInterface(result.Interfaces)
+
+	netns, err := ns.GetNS(args.Netns)
+	if err != nil {
+		return fmt.Errorf("failed to open netns %q: %v", netns, err)
+	}
+	defer netns.Close()
+
+	hostInterface, err := getHostInterface(result.Interfaces, args.IfName, netns)
 	if err != nil {
 		return err
 	}
@@ -266,7 +287,13 @@ func cmdCheck(args *skel.CmdArgs) error {
 		return fmt.Errorf("could not convert result to current version: %v", err)
 	}
 
-	hostInterface, err := getHostInterface(result.Interfaces)
+	netns, err := ns.GetNS(args.Netns)
+	if err != nil {
+		return fmt.Errorf("failed to open netns %q: %v", netns, err)
+	}
+	defer netns.Close()
+
+	hostInterface, err := getHostInterface(result.Interfaces, args.IfName, netns)
 	if err != nil {
 		return err
 	}