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state.go
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state.go
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// Copyright (c) 2018-2019, AT&T Intellectual Property. All rights reserved.
// SPDX-License-Identifier: GPL-2.0-only
package forwarding
import (
"bytes"
"errors"
"io"
"io/ioutil"
"os"
"path/filepath"
"regexp"
"strconv"
"strings"
"sync"
"sync/atomic"
"syscall"
"time"
"github.com/danos/vyatta-service-dns/internal/log"
"github.com/danos/vyatta-service-dns/internal/process"
"github.com/fsnotify/fsnotify"
"github.com/msoap/byline"
)
type StateData struct {
State struct {
QueriesForwarded uint64 `rfc7951:"queries-forwarded"`
QueriesAnswered uint64 `rfc7951:"queries-answered"`
Cache struct {
Size uint32 `rfc7951:"size"`
Entries uint64 `rfc7951:"cache-entries"`
ReusedEntries uint64 `rfc7951:"reused-cache-entries"`
} `rfc7951:"cache,omitempty"`
Nameservers []NameserverState `rfc7951:"nameservers,omitempty"`
} `rfc7951:"state,omitempty"`
}
type NameserverState struct {
IPAddress string `rfc7951:"address"`
Port uint16 `rfc7951:"port"`
QueriesSent uint64 `rfc7951:"queries-sent"`
QueriesRetriedOrFailed uint64 `rfc7951:"queries-retried-or-failed"`
Provenance string `rfc7951:"provenance"`
InUse bool `rfc7951:"in-use"`
DomainOverrideOnly bool `rfc7951:"domain-override-only"`
Domains []string `rfc7951:"domains,omitempty"`
}
type State struct {
mu sync.Mutex
state atomic.Value
p process.Process
statefile string
resolvfile string
conffile string
}
func NewState(config *Config) *State {
s := &State{
p: config.forwardingProcess,
statefile: config.statefile,
resolvfile: config.resolvfile,
conffile: config.conffile,
}
s.state.Store(&StateData{})
return s
}
func (s *State) Get() *StateData {
const logPrefix = "forwarding-state-get:"
// Only one Get at a time can happen since we have to destroy the old file.
s.mu.Lock()
defer s.mu.Unlock()
err := os.Truncate(s.statefile, 0)
if err != nil {
log.Dlog.Println(logPrefix, err)
}
watcher := s.prepareWatcher()
s.requestState()
gotIt := s.waitForState(watcher)
if !gotIt {
// Timeout or error, just return the previous state.
return s.state.Load().(*StateData)
}
stateFile, err := os.Open(s.statefile)
if err != nil {
log.Dlog.Println(logPrefix, err)
return s.state.Load().(*StateData)
}
defer stateFile.Close()
resolvFile, err := os.Open(s.resolvfile)
if err != nil {
log.Dlog.Println(logPrefix, err)
}
defer resolvFile.Close()
dnsmasqFile, err := os.Open(s.conffile)
if err != nil {
log.Dlog.Println(logPrefix, err)
}
defer dnsmasqFile.Close()
reader := &stateReader{
dnsmasqStateReader: stateFile,
resolvConfReader: resolvFile,
dnsmasqConfReader: dnsmasqFile,
}
state := reader.Read()
s.state.Store(state)
return state
}
func (s *State) requestState() {
const logPrefix = "forwarding state requester:"
err := s.p.Signal(syscall.SIGUSR1)
if err != nil {
log.Elog.Println(logPrefix, err)
}
}
func (s *State) prepareWatcher() *fsnotify.Watcher {
watcher, err := fsnotify.NewWatcher()
if err != nil {
panic(err)
}
watcher.Add(filepath.Dir(s.statefile))
return watcher
}
func (s *State) waitForState(watcher *fsnotify.Watcher) bool {
const logPrefix = "forwarding state watcher:"
defer watcher.Close()
for {
select {
case event := <-watcher.Events:
switch {
case event.Op&(fsnotify.CloseWrite|fsnotify.Write) != 0:
if event.Name != s.statefile {
continue
}
return true
}
case err := <-watcher.Errors:
log.Wlog.Println(logPrefix, err)
case <-time.After(1 * time.Second):
log.Wlog.Println(logPrefix, "timeout")
return false
}
}
}
type stateReader struct {
dnsmasqStateReader io.Reader
resolvConfReader io.Reader
dnsmasqConfReader io.Reader
}
func (s *stateReader) Read() *StateData {
//This is a more or less exact port of the old perl state parser.
//It has been slightly cleaned up, but could probably be cleaner.
state := s.ReadState()
s.ReadProvenance(state)
return state
}
func (s *stateReader) ReadState() *StateData {
if s.dnsmasqStateReader == nil {
return &StateData{}
}
return readStateData(s.dnsmasqStateReader)
}
func (s *stateReader) ReadProvenance(state *StateData) {
if s.resolvConfReader == nil || s.dnsmasqConfReader == nil {
return
}
resolvNs := readResolvNs(s.resolvConfReader)
dhcpNs := readDhclientNs()
pppNs := readPPPNs()
dnsmasqNs := readDnsmasqNs(s.dnsmasqConfReader)
ns := make(map[string]*NameserverState)
resolvNsM := make(map[string]struct{})
// By default nothing is in use by dnsmasq unless there are no
// configured non-domain override servers
inUse := true
for _, ns := range dnsmasqNs {
if ns.Domain == "" {
inUse = false
break
}
}
// Find all the nameservers the system knows about and their provenance.
// This may not be entirely correct but replicates the legacy behavior.
for _, n := range resolvNs {
resolvNsM[n] = struct{}{}
ns[n] = &NameserverState{
IPAddress: n,
Port: 53,
Provenance: "system",
InUse: inUse,
}
}
// Only record dhcpNs that make it into resolv.conf
for _, n := range dhcpNs {
_, ok := resolvNsM[n]
if !ok {
continue
}
ns[n] = &NameserverState{
IPAddress: n,
Port: 53,
Provenance: "dhcp",
InUse: inUse,
}
}
// Only record pppNs that make it into resolv.conf
for _, n := range pppNs {
_, ok := resolvNsM[n]
if !ok {
continue
}
ns[n] = &NameserverState{
IPAddress: n,
Port: 53,
Provenance: "ppp",
InUse: inUse,
}
}
// Adjust the list for the dnsmasq configuration file
for _, n := range dnsmasqNs {
s, ok := ns[n.Server]
if ok {
s.Provenance = "configuration"
s.InUse = true
if n.Domain != "" {
s.Domains = append(s.Domains, n.Domain)
} else {
s.DomainOverrideOnly = false
}
} else {
s := &NameserverState{
IPAddress: n.Server,
Port: 53,
Provenance: "configuration",
InUse: true,
DomainOverrideOnly: true,
}
if n.Domain != "" {
s.Domains = []string{n.Domain}
} else {
s.DomainOverrideOnly = false
}
ns[n.Server] = s
}
}
// Update the list of servers discovered by the state file
seen := make(map[string]struct{})
for i, v := range state.State.Nameservers {
seen[v.IPAddress] = struct{}{}
s, ok := ns[v.IPAddress]
if !ok {
continue
}
v.Provenance = s.Provenance
v.Domains = s.Domains
v.InUse = s.InUse
v.DomainOverrideOnly = s.DomainOverrideOnly
state.State.Nameservers[i] = v
}
// Finally add in any servers that weren't in the state file
for k, v := range ns {
if _, ok := seen[k]; ok {
continue
}
state.State.Nameservers = append(state.State.Nameservers, *v)
}
}
func readStateData(r io.Reader) *StateData {
logPrefix := "read-state-data"
state := &StateData{}
data, err := ioutil.ReadAll(r)
if err != nil {
return state
}
br := bytes.NewReader(data)
err = readCacheStats(state, br)
if err != nil {
log.Dlog.Println(logPrefix, err)
}
br.Reset(data)
err = readQueryStats(state, br)
if err != nil {
log.Dlog.Println(logPrefix, err)
}
br.Reset(data)
err = readNameserverStats(state, br)
if err != nil {
log.Dlog.Println(logPrefix, err)
}
return state
}
func readCacheStats(state *StateData, r io.Reader) error {
return byline.NewReader(r).
GrepByRegexp(regexp.MustCompile("cache size")).
AWKMode(func(line string, fields []string, vars byline.AWKVars) (string, error) {
if len(fields) < 8 {
log.Dlog.Println("read-cache-stats",
errors.New("invalid cache statistics line in log file"))
return "", nil
}
size, err := strconv.ParseUint(strings.Trim(fields[6], ","), 10, 32)
if err != nil {
log.Dlog.Println("read-cache-stats:", "cache size:", err)
}
state.State.Cache.Size = uint32(size)
entries := strings.Split(fields[7], "/")
if len(entries) != 2 {
log.Dlog.Println("read-cache-stats",
errors.New("cache entries: unexpected format of entries field"))
return "", nil
}
all, err := strconv.ParseUint(entries[1], 10, 64)
if err != nil {
log.Dlog.Println("read-cache-stats:", "cache entries:", err)
}
reused, err := strconv.ParseUint(entries[0], 10, 64)
if err != nil {
log.Dlog.Println("read-cache-stats:", "cache entries:", err)
}
state.State.Cache.Entries = all
state.State.Cache.ReusedEntries = reused
return "", nil
}).
Discard()
}
func readQueryStats(state *StateData, r io.Reader) error {
return byline.NewReader(r).
GrepByRegexp(regexp.MustCompile("queries forwarded")).
AWKMode(func(line string, fields []string, vars byline.AWKVars) (string, error) {
if len(fields) < 11 {
log.Dlog.Println("read-query-stats",
errors.New("invalid query statistics line in log file"))
return "", nil
}
forwarded, err := strconv.ParseUint(strings.Trim(fields[6], ","), 10, 64)
if err != nil {
log.Dlog.Println("read-query-stats:", "forwarded:", err)
}
state.State.QueriesForwarded = forwarded
answered, err := strconv.ParseUint(fields[10], 10, 64)
if err != nil {
log.Dlog.Println("read-query-stats:", "answered:", err)
}
state.State.QueriesAnswered = answered
return "", nil
}).
Discard()
}
func readNameserverStats(state *StateData, r io.Reader) error {
var nameservers []NameserverState
err := byline.NewReader(r).
GrepByRegexp(regexp.MustCompile("server")).
AWKMode(func(line string, fields []string, vars byline.AWKVars) (string, error) {
if len(fields) < 13 {
log.Dlog.Println("read-nameserver-stats:",
errors.New("invalid server line in log file: "+line))
return "", nil
}
queriesSent, err := strconv.ParseUint(strings.Trim(fields[8], ","), 10, 64)
if err != nil {
log.Dlog.Println("read-nameserver-stats:", "sent:", err)
}
queriesRetried, err := strconv.ParseUint(fields[12], 10, 64)
if err != nil {
log.Dlog.Println("read-nameserver-stats:", "retried:", err)
}
serverPort := strings.Split(strings.Trim(fields[5], ":"), "#")
var server string
var port uint64
if len(serverPort) != 2 {
log.Dlog.Println("read-nameserver-stats:",
errors.New("invalid server line in log file: "+line))
return "", nil
}
server = serverPort[0]
port, err = strconv.ParseUint(serverPort[1], 10, 16)
if err != nil {
log.Dlog.Println("read-nameserver-stats:", "port:", err)
}
nameservers = append(nameservers, NameserverState{
IPAddress: server,
Port: uint16(port),
QueriesSent: queriesSent,
QueriesRetriedOrFailed: queriesRetried,
Provenance: "system",
InUse: true,
})
return "", nil
}).
Discard()
state.State.Nameservers = nameservers
return err
}
func readResolvNs(r io.Reader) []string {
var ns []string
err := byline.NewReader(r).
GrepByRegexp(regexp.MustCompile("^nameserver")).
AWKMode(func(line string, fields []string, vars byline.AWKVars) (string, error) {
ns = append(ns, fields[1])
return "", nil
}).
Discard()
if err != nil {
log.Dlog.Println("read-resolv-nameservers:", err)
}
return ns
}
func readAllGlobNs(glob string) []string {
var out []string
files, err := filepath.Glob(glob)
if err != nil {
log.Dlog.Println("read-all-glob-ns", glob+":", err)
return nil
}
for _, file := range files {
f, err := os.Open(file)
if err != nil {
log.Dlog.Println("read-all-glob-ns", glob+":", err)
continue
}
out = append(out, readResolvNs(f)...)
f.Close()
}
return out
}
func readDhclientNs() []string {
const (
dhclientResolvPat = "/var/lib/dhcp/dhclient-*-resolv.conf"
)
return readAllGlobNs(dhclientResolvPat)
}
func readPPPNs() []string {
const (
pppResolvPat = "/etc/ppp/resolv-*.conf"
)
return readAllGlobNs(pppResolvPat)
}
type dnsMasqNs struct {
Server string
Domain string
}
func readDnsmasqNs(r io.Reader) []dnsMasqNs {
var ns []dnsMasqNs
serverExp := regexp.MustCompile("server=")
confDirExp := regexp.MustCompile("conf-dir=")
err := byline.NewReader(r).
SetFS(regexp.MustCompile("[=\\s]+")).
AWKMode(func(line string, fields []string, vars byline.AWKVars) (string, error) {
switch {
case serverExp.MatchString(line):
if fields[3] == "domain-override" {
domIp := strings.Split(fields[1], "/")
ns = append(ns, dnsMasqNs{Server: domIp[2], Domain: domIp[1]})
} else {
ns = append(ns, dnsMasqNs{Server: fields[1]})
}
return "", nil
case confDirExp.MatchString(line):
dirGlob := strings.Split(fields[1], ",")
dir := dirGlob[0]
globs := dirGlob[1:]
for _, glob := range globs {
globpath := dir + "/" + glob
files, err := filepath.Glob(globpath)
if err != nil {
log.Dlog.Println("read-dnsmasq-conf-dir", glob+":", err)
continue
}
for _, file := range files {
f, err := os.Open(file)
if err != nil {
log.Dlog.Println("read-dnsmasq-conf-dir", glob+":", err)
continue
}
ns = append(ns, readDnsmasqNs(f)...)
f.Close()
}
}
}
return "", nil
}).
Discard()
if err != nil {
log.Dlog.Println("read-dnsmasq-nameservers:", err)
}
return ns
}