pkg/meta/bandwidth: increase IfbDeviceName size

* Increase entroy from 2 bytes to 7 bytes to prevent collisions
* Extract common library function for hash with prefix
* Refactor portmap plugin to use library function

fixes #347

Co-authored-by: Cameron Moreau <cmoreau@pivotal.io>
Co-authored-by: Mikael Manukyan <mmanukyan@pivotal.io>

plugins/meta/bandwidth/bandwidth_linux_test.go

@@ -105,7 +105,7 @@ var _ = Describe("bandwidth test", func() {
 		hostIP = net.IP{169, 254, 0, 1}
 		containerIP = net.IP{10, 254, 0, 1}
 		hostIfaceMTU = 1024
-		ifbDeviceName = "5b6c"
+		ifbDeviceName = "bwpa8eda89404b7"
 
 		createVeth(hostNs.Path(), hostIfname, containerNs.Path(), containerIfname, hostIP, containerIP, hostIfaceMTU)
 	})

plugins/meta/bandwidth/main.go

@@ -15,7 +15,6 @@
 package main
 
 import (
-	"crypto/sha1"
 	"encoding/json"
 	"fmt"
 
@@ -28,9 +27,13 @@ import (
 
 	"github.com/containernetworking/plugins/pkg/ip"
 	"github.com/containernetworking/plugins/pkg/ns"
+	"github.com/containernetworking/plugins/pkg/utils"
 	bv "github.com/containernetworking/plugins/pkg/utils/buildversion"
 )
 
+const maxIfbDeviceLength = 15
+const ifbDevicePrefix = "bwp"
+
 // BandwidthEntry corresponds to a single entry in the bandwidth argument,
 // see CONVENTIONS.md
 type BandwidthEntry struct {
@@ -111,14 +114,8 @@ func validateRateAndBurst(rate int, burst int) error {
 	return nil
 }
 
-func getIfbDeviceName(networkName string, containerId string) (string, error) {
-	hash := sha1.New()
-	_, err := hash.Write([]byte(networkName + containerId))
-	if err != nil {
-		return "", err
-	}
-
-	return fmt.Sprintf("%x", hash.Sum(nil))[:4], nil
+func getIfbDeviceName(networkName string, containerId string) string {
+	return utils.MustFormatHashWithPrefix(maxIfbDeviceLength, ifbDevicePrefix, networkName+containerId)
 }
 
 func getMTU(deviceName string) (int, error) {
@@ -205,10 +202,7 @@ func cmdAdd(args *skel.CmdArgs) error {
 			return err
 		}
 
-		ifbDeviceName, err := getIfbDeviceName(conf.Name, args.ContainerID)
-		if err != nil {
-			return err
-		}
+		ifbDeviceName := getIfbDeviceName(conf.Name, args.ContainerID)
 
 		err = CreateIfb(ifbDeviceName, mtu)
 		if err != nil {
@@ -239,10 +233,7 @@ func cmdDel(args *skel.CmdArgs) error {
 		return err
 	}
 
-	ifbDeviceName, err := getIfbDeviceName(conf.Name, args.ContainerID)
-	if err != nil {
-		return err
-	}
+	ifbDeviceName := getIfbDeviceName(conf.Name, args.ContainerID)
 
 	if err := TeardownIfb(ifbDeviceName); err != nil {
 		return err
@@ -343,10 +334,7 @@ func cmdCheck(args *skel.CmdArgs) error {
 		latency := latencyInUsec(latencyInMillis)
 		limitInBytes := limit(uint64(rateInBytes), latency, uint32(burstInBytes))
 
-		ifbDeviceName, err := getIfbDeviceName(bwConf.Name, args.ContainerID)
-		if err != nil {
-			return err
-		}
+		ifbDeviceName := getIfbDeviceName(bwConf.Name, args.ContainerID)
 
 		ifbDevice, err := netlink.LinkByName(ifbDeviceName)
 		if err != nil {

plugins/meta/portmap/portmap.go

@@ -20,6 +20,7 @@ import (
 	"sort"
 	"strconv"
 
+	"github.com/containernetworking/plugins/pkg/utils"
 	"github.com/containernetworking/plugins/pkg/utils/sysctl"
 	"github.com/coreos/go-iptables/iptables"
 )
@@ -172,7 +173,7 @@ func genToplevelDnatChain() chain {
 func genDnatChain(netName, containerID string) chain {
 	return chain{
 		table:       "nat",
-		name:        formatChainName("DN-", netName, containerID),
+		name:        utils.MustFormatChainNameWithPrefix(netName, containerID, "DN-"),
 		entryChains: []string{TopLevelDNATChainName},
 	}
 }
@@ -323,11 +324,9 @@ func enableLocalnetRouting(ifName string) error {
 // genOldSnatChain is no longer used, but used to be created. We'll try and
 // tear it down in case the plugin version changed between ADD and DEL
 func genOldSnatChain(netName, containerID string) chain {
-	name := formatChainName("SN-", netName, containerID)
-
 	return chain{
 		table:       "nat",
-		name:        name,
+		name:        utils.MustFormatChainNameWithPrefix(netName, containerID, "SN-"),
 		entryChains: []string{OldTopLevelSNATChainName},
 	}
 }

plugins/meta/portmap/utils.go

@@ -15,7 +15,6 @@
 package main
 
 import (
-	"crypto/sha512"
 	"fmt"
 	"net"
 	"strconv"
@@ -24,8 +23,6 @@ import (
 	"github.com/vishvananda/netlink"
 )
 
-const maxChainNameLength = 28
-
 // fmtIpPort correctly formats ip:port literals for iptables and ip6tables -
 // need to wrap v6 literals in a []
 func fmtIpPort(ip net.IP, port int) string {
@@ -62,12 +59,6 @@ func getRoutableHostIF(containerIP net.IP) string {
 	return ""
 }
 
-func formatChainName(prefix, name, id string) string {
-	chainBytes := sha512.Sum512([]byte(name + id))
-	chain := fmt.Sprintf("CNI-%s%x", prefix, chainBytes)
-	return chain[:maxChainNameLength]
-}
-
 // groupByProto groups port numbers by protocol
 func groupByProto(entries []PortMapEntry) map[string][]int {
 	if len(entries) == 0 {