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iptm.go
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iptm.go
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package iptm
import (
"os"
"os/exec"
"syscall"
"github.com/Azure/azure-container-networking/log"
"github.com/Azure/azure-container-networking/npm/util"
)
// IptEntry represents an iptables rule.
type IptEntry struct {
Name string
HashedName string
Chain string
Flag string
Specs []string
}
// IptablesManager stores iptables entries.
type IptablesManager struct {
OperationFlag string
}
// NewIptablesManager creates a new instance for IptablesManager object.
func NewIptablesManager() *IptablesManager {
iptMgr := &IptablesManager{
OperationFlag: "",
}
return iptMgr
}
// InitNpmChains initializes Azure NPM chains in iptables.
func (iptMgr *IptablesManager) InitNpmChains() error {
log.Printf("Initializing AZURE-NPM chains")
if err := iptMgr.AddChain(util.IptablesAzureChain); err != nil {
return err
}
// Insert AZURE-NPM chain to FORWARD chain.
entry := &IptEntry{
Chain: util.IptablesForwardChain,
Specs: []string{
util.IptablesJumpFlag,
util.IptablesAzureChain,
},
}
exists, err := iptMgr.Exists(entry)
if err != nil {
return err
}
if !exists {
iptMgr.OperationFlag = util.IptablesInsertionFlag
if _, err = iptMgr.Run(entry); err != nil {
log.Printf("Error adding AZURE-NPM chain to FORWARD chain\n")
return err
}
}
// Add default allow CONNECTED/RELATED rule to AZURE-NPM chain.
entry.Chain = util.IptablesAzureChain
entry.Specs = []string{
util.IptablesMatchFlag,
util.IptablesStateFlag,
util.IptablesMatchStateFlag,
util.IptablesRelatedState + "," + util.IptablesEstablishedState,
util.IptablesJumpFlag,
util.IptablesAccept,
}
exists, err = iptMgr.Exists(entry)
if err != nil {
return err
}
if !exists {
iptMgr.OperationFlag = util.IptablesInsertionFlag
if _, err = iptMgr.Run(entry); err != nil {
log.Printf("Error adding default allow CONNECTED/RELATED rule to AZURE-NPM chain\n")
return err
}
}
// Create AZURE-NPM-INGRESS-PORT chain.
if err := iptMgr.AddChain(util.IptablesAzureIngressPortChain); err != nil {
return err
}
// Insert AZURE-NPM-INGRESS-PORT chain to AZURE-NPM chain.
entry.Chain = util.IptablesAzureChain
entry.Specs = []string{util.IptablesJumpFlag, util.IptablesAzureIngressPortChain}
exists, err = iptMgr.Exists(entry)
if err != nil {
return err
}
if !exists {
iptMgr.OperationFlag = util.IptablesAppendFlag
if _, err := iptMgr.Run(entry); err != nil {
log.Printf("Error adding AZURE-NPM-INGRESS-PORT chain to AZURE-NPM chain\n")
return err
}
}
// Create AZURE-NPM-INGRESS-FROM-NS chain.
if err = iptMgr.AddChain(util.IptablesAzureIngressFromNsChain); err != nil {
return err
}
// Create AZURE-NPM-INGRESS-FROM-POD chain.
if err = iptMgr.AddChain(util.IptablesAzureIngressFromPodChain); err != nil {
return err
}
// Create AZURE-NPM-EGRESS-PORT chain.
if err := iptMgr.AddChain(util.IptablesAzureEgressPortChain); err != nil {
return err
}
// Insert AZURE-NPM-EGRESS-PORT chain to AZURE-NPM chain.
entry.Chain = util.IptablesAzureChain
entry.Specs = []string{util.IptablesJumpFlag, util.IptablesAzureEgressPortChain}
exists, err = iptMgr.Exists(entry)
if err != nil {
return err
}
if !exists {
iptMgr.OperationFlag = util.IptablesAppendFlag
if _, err := iptMgr.Run(entry); err != nil {
log.Printf("Error adding AZURE-NPM-EGRESS-PORT chain to AZURE-NPM chain\n")
return err
}
}
// Create AZURE-NPM-EGRESS-TO-NS chain.
if err = iptMgr.AddChain(util.IptablesAzureEgressToNsChain); err != nil {
return err
}
// Create AZURE-NPM-EGRESS-TO-POD chain.
if err = iptMgr.AddChain(util.IptablesAzureEgressToPodChain); err != nil {
return err
}
// Create AZURE-NPM-TARGET-SETS chain.
if err := iptMgr.AddChain(util.IptablesAzureTargetSetsChain); err != nil {
return err
}
// Insert AZURE-NPM-TARGET-SETS chain to AZURE-NPM chain.
entry.Chain = util.IptablesAzureChain
entry.Specs = []string{util.IptablesJumpFlag, util.IptablesAzureTargetSetsChain}
exists, err = iptMgr.Exists(entry)
if err != nil {
return err
}
if !exists {
iptMgr.OperationFlag = util.IptablesAppendFlag
if _, err := iptMgr.Run(entry); err != nil {
log.Printf("Error adding AZURE-NPM-TARGET-SETS chain to AZURE-NPM chain\n")
return err
}
}
return nil
}
// UninitNpmChains uninitializes Azure NPM chains in iptables.
func (iptMgr *IptablesManager) UninitNpmChains() error {
IptablesAzureChainList := []string{
util.IptablesAzureChain,
util.IptablesAzureIngressPortChain,
util.IptablesAzureIngressFromNsChain,
util.IptablesAzureIngressFromPodChain,
util.IptablesAzureEgressPortChain,
util.IptablesAzureEgressToNsChain,
util.IptablesAzureEgressToPodChain,
util.IptablesAzureTargetSetsChain,
}
// Remove AZURE-NPM chain from FORWARD chain.
entry := &IptEntry{
Chain: util.IptablesForwardChain,
Specs: []string{
util.IptablesJumpFlag,
util.IptablesAzureChain,
},
}
iptMgr.OperationFlag = util.IptablesDeletionFlag
errCode, err := iptMgr.Run(entry)
if errCode != 1 && err != nil {
log.Printf("Error removing default rule from FORWARD chain\n")
return err
}
iptMgr.OperationFlag = util.IptablesFlushFlag
for _, chain := range IptablesAzureChainList {
entry := &IptEntry{
Chain: chain,
}
if _, err := iptMgr.Run(entry); err != nil {
log.Printf("Error flushing iptables chain %s\n", chain)
}
}
for _, chain := range IptablesAzureChainList {
if err := iptMgr.DeleteChain(chain); err != nil {
return err
}
}
return nil
}
// Exists checks if a rule exists in iptables.
func (iptMgr *IptablesManager) Exists(entry *IptEntry) (bool, error) {
iptMgr.OperationFlag = util.IptablesCheckFlag
returnCode, err := iptMgr.Run(entry)
if err == nil {
log.Printf("Rule exists. %+v\n", entry)
return true, nil
}
if returnCode == 1 {
log.Printf("Rule doesn't exist. %+v\n", entry)
return false, nil
}
return false, err
}
// AddChain adds a chain to iptables.
func (iptMgr *IptablesManager) AddChain(chain string) error {
entry := &IptEntry{
Chain: chain,
}
iptMgr.OperationFlag = util.IptablesChainCreationFlag
errCode, err := iptMgr.Run(entry)
if err != nil {
if errCode == 1 {
log.Printf("Chain already exists %s\n", entry.Chain)
return nil
}
log.Printf("Error creating iptables chain %s\n", entry.Chain)
return err
}
return nil
}
// DeleteChain deletes a chain from iptables.
func (iptMgr *IptablesManager) DeleteChain(chain string) error {
entry := &IptEntry{
Chain: chain,
}
iptMgr.OperationFlag = util.IptablesDestroyFlag
errCode, err := iptMgr.Run(entry)
if err != nil {
if errCode == 1 {
log.Printf("Chain doesn't exist %s\n", entry.Chain)
return nil
}
log.Printf("Error deleting iptables chain %s\n", entry.Chain)
return err
}
return nil
}
// Add adds a rule in iptables.
func (iptMgr *IptablesManager) Add(entry *IptEntry) error {
log.Printf("Add iptables entry: %+v\n", entry)
exists, err := iptMgr.Exists(entry)
if err != nil {
return err
}
if exists {
return nil
}
iptMgr.OperationFlag = util.IptablesInsertionFlag
if _, err := iptMgr.Run(entry); err != nil {
log.Printf("Error creating iptables rules.\n")
return err
}
return nil
}
// Delete removes a rule in iptables.
func (iptMgr *IptablesManager) Delete(entry *IptEntry) error {
log.Printf("Deleting iptables entry: %+v\n", entry)
exists, err := iptMgr.Exists(entry)
if err != nil {
return err
}
if !exists {
return nil
}
iptMgr.OperationFlag = util.IptablesDeletionFlag
if _, err := iptMgr.Run(entry); err != nil {
log.Printf("Error deleting iptables rules.\n")
return err
}
return nil
}
// Run execute an iptables command to update iptables.
func (iptMgr *IptablesManager) Run(entry *IptEntry) (int, error) {
cmdName := util.Iptables
cmdArgs := append([]string{iptMgr.OperationFlag, entry.Chain}, entry.Specs...)
cmdOut, err := exec.Command(cmdName, cmdArgs...).Output()
log.Printf("%s\n", string(cmdOut))
if msg, failed := err.(*exec.ExitError); failed {
errCode := msg.Sys().(syscall.WaitStatus).ExitStatus()
if errCode > 1 {
log.Printf("There was an error running command: %s\nArguments:%+v", err, cmdArgs)
}
return errCode, err
}
return 0, nil
}
// Save saves current iptables configuration to /var/log/iptables.conf
func (iptMgr *IptablesManager) Save(configFile string) error {
if len(configFile) == 0 {
configFile = util.IptablesConfigFile
}
// create the config file for writing
f, err := os.Create(configFile)
if err != nil {
log.Printf("Error opening file: %s.", configFile)
return err
}
defer f.Close()
cmd := exec.Command(util.IptablesSave)
cmd.Stdout = f
if err := cmd.Start(); err != nil {
log.Printf("Error running iptables-save.\n")
return err
}
cmd.Wait()
return nil
}
// Restore restores iptables configuration from /var/log/iptables.conf
func (iptMgr *IptablesManager) Restore(configFile string) error {
if len(configFile) == 0 {
configFile = util.IptablesConfigFile
}
// open the config file for reading
f, err := os.Open(configFile)
if err != nil {
log.Printf("Error opening file: %s.", configFile)
return err
}
defer f.Close()
cmd := exec.Command(util.IptablesRestore)
cmd.Stdin = f
if err := cmd.Start(); err != nil {
log.Printf("Error running iptables-restore.\n")
return err
}
cmd.Wait()
return nil
}