Pull request: all: fix lint and naming issues vol. 4
Merge in DNS/adguard-home from 2276-fix-lint-4 to master Updates #2276. Squashed commit of the following: commit 15d49184cd8ce1f8701bf3221e69418ca1778b36 Author: Ainar Garipov <A.Garipov@AdGuard.COM> Date: Tue Dec 8 15:51:34 2020 +0300 util: fix naming commit 3b9a86a0feb8c6e0b167e6e23105e8137b0dda76 Author: Ainar Garipov <A.Garipov@AdGuard.COM> Date: Tue Dec 8 15:41:10 2020 +0300 all: fix lint and naming issues vol. 4
This commit is contained in:
Ainar Garipov
353
internal/util/autohosts.go
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353
internal/util/autohosts.go
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package util
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import (
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"bufio"
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"io"
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"io/ioutil"
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"net"
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"os"
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"runtime"
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"strings"
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"sync"
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"github.com/miekg/dns"
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"github.com/AdguardTeam/golibs/log"
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"github.com/fsnotify/fsnotify"
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)
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type onChangedT func()
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// AutoHosts - automatic DNS records
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type AutoHosts struct {
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// lock protects table and tableReverse.
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lock sync.Mutex
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// table is the host-to-IPs map.
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table map[string][]net.IP
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// tableReverse is the IP-to-hosts map.
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//
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// TODO(a.garipov): Make better use of newtypes. Perhaps a custom map.
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tableReverse map[string][]string
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hostsFn string // path to the main hosts-file
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hostsDirs []string // paths to OS-specific directories with hosts-files
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watcher *fsnotify.Watcher // file and directory watcher object
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updateChan chan bool // signal for 'updateLoop' goroutine
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onChanged onChangedT // notification to other modules
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}
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// SetOnChanged - set callback function that will be called when the data is changed
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func (a *AutoHosts) SetOnChanged(onChanged onChangedT) {
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a.onChanged = onChanged
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}
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// Notify other modules
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func (a *AutoHosts) notify() {
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if a.onChanged == nil {
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return
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}
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a.onChanged()
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}
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// Init - initialize
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// hostsFn: Override default name for the hosts-file (optional)
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func (a *AutoHosts) Init(hostsFn string) {
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a.table = make(map[string][]net.IP)
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a.updateChan = make(chan bool, 2)
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a.hostsFn = "/etc/hosts"
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if runtime.GOOS == "windows" {
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a.hostsFn = os.ExpandEnv("$SystemRoot\\system32\\drivers\\etc\\hosts")
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}
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if len(hostsFn) != 0 {
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a.hostsFn = hostsFn
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}
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if IsOpenWRT() {
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a.hostsDirs = append(a.hostsDirs, "/tmp/hosts") // OpenWRT: "/tmp/hosts/dhcp.cfg01411c"
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}
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// Load hosts initially
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a.updateHosts()
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var err error
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a.watcher, err = fsnotify.NewWatcher()
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if err != nil {
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log.Error("AutoHosts: %s", err)
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}
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}
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// Start - start module
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func (a *AutoHosts) Start() {
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log.Debug("Start AutoHosts module")
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go a.updateLoop()
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a.updateChan <- true
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if a.watcher != nil {
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go a.watcherLoop()
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err := a.watcher.Add(a.hostsFn)
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if err != nil {
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log.Error("Error while initializing watcher for a file %s: %s", a.hostsFn, err)
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}
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for _, dir := range a.hostsDirs {
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err = a.watcher.Add(dir)
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if err != nil {
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log.Error("Error while initializing watcher for a directory %s: %s", dir, err)
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}
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}
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}
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}
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// Close - close module
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func (a *AutoHosts) Close() {
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a.updateChan <- false
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close(a.updateChan)
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if a.watcher != nil {
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_ = a.watcher.Close()
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}
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}
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// Process returns the list of IP addresses for the hostname or nil if nothing
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// found.
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func (a *AutoHosts) Process(host string, qtype uint16) []net.IP {
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if qtype == dns.TypePTR {
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return nil
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}
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var ipsCopy []net.IP
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a.lock.Lock()
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if ips, ok := a.table[host]; ok {
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ipsCopy = make([]net.IP, len(ips))
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copy(ipsCopy, ips)
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}
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a.lock.Unlock()
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log.Debug("AutoHosts: answer: %s -> %v", host, ipsCopy)
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return ipsCopy
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}
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// ProcessReverse processes a PTR request. It returns nil if nothing is found.
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func (a *AutoHosts) ProcessReverse(addr string, qtype uint16) (hosts []string) {
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if qtype != dns.TypePTR {
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return nil
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}
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ipReal := DNSUnreverseAddr(addr)
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if ipReal == nil {
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return nil
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}
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ipStr := ipReal.String()
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a.lock.Lock()
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defer a.lock.Unlock()
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hosts = a.tableReverse[ipStr]
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if len(hosts) == 0 {
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return nil // not found
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}
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log.Debug("AutoHosts: reverse-lookup: %s -> %s", addr, hosts)
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return hosts
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}
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// List returns an IP-to-hostnames table. It is safe for concurrent use.
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func (a *AutoHosts) List() (ipToHosts map[string][]string) {
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a.lock.Lock()
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defer a.lock.Unlock()
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ipToHosts = make(map[string][]string, len(a.tableReverse))
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for k, v := range a.tableReverse {
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ipToHosts[k] = v
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}
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return ipToHosts
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}
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// update table
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func (a *AutoHosts) updateTable(table map[string][]net.IP, host string, ipAddr net.IP) {
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ips, ok := table[host]
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if ok {
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for _, ip := range ips {
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if ip.Equal(ipAddr) {
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// IP already exists: don't add duplicates
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ok = false
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break
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}
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}
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if !ok {
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ips = append(ips, ipAddr)
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table[host] = ips
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}
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} else {
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table[host] = []net.IP{ipAddr}
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ok = true
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}
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if ok {
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log.Debug("AutoHosts: added %s -> %s", ipAddr, host)
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}
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}
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// updateTableRev updates the reverse address table.
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func (a *AutoHosts) updateTableRev(tableRev map[string][]string, newHost string, ipAddr net.IP) {
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ipStr := ipAddr.String()
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hosts, ok := tableRev[ipStr]
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if !ok {
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tableRev[ipStr] = []string{newHost}
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log.Debug("AutoHosts: added reverse-address %s -> %s", ipStr, newHost)
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return
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}
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for _, host := range hosts {
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if host == newHost {
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return
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}
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}
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tableRev[ipStr] = append(tableRev[ipStr], newHost)
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log.Debug("AutoHosts: added reverse-address %s -> %s", ipStr, newHost)
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}
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// Read IP-hostname pairs from file
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// Multiple hostnames per line (per one IP) is supported.
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func (a *AutoHosts) load(table map[string][]net.IP, tableRev map[string][]string, fn string) {
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f, err := os.Open(fn)
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if err != nil {
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log.Error("AutoHosts: %s", err)
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return
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}
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defer f.Close()
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r := bufio.NewReader(f)
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log.Debug("AutoHosts: loading hosts from file %s", fn)
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finish := false
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for !finish {
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line, err := r.ReadString('\n')
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if err == io.EOF {
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finish = true
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} else if err != nil {
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log.Error("AutoHosts: %s", err)
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return
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}
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line = strings.TrimSpace(line)
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if len(line) == 0 || line[0] == '#' {
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continue
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}
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fields := strings.Fields(line)
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if len(fields) < 2 {
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continue
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}
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ipAddr := net.ParseIP(fields[0])
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if ipAddr == nil {
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continue
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}
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for i := 1; i != len(fields); i++ {
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host := fields[i]
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if len(host) == 0 {
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break
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}
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sharp := strings.IndexByte(host, '#')
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if sharp == 0 {
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break // skip the rest of the line after #
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} else if sharp > 0 {
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host = host[:sharp]
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}
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a.updateTable(table, host, ipAddr)
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a.updateTableRev(tableRev, host, ipAddr)
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if sharp >= 0 {
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break // skip the rest of the line after #
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}
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}
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}
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}
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// Receive notifications from fsnotify package
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func (a *AutoHosts) watcherLoop() {
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for {
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select {
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case event, ok := <-a.watcher.Events:
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if !ok {
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return
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}
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repeat := true
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for repeat {
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select {
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case <-a.watcher.Events:
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// Skip this duplicating event
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default:
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repeat = false
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}
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}
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if event.Op&fsnotify.Write == fsnotify.Write {
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log.Debug("AutoHosts: modified: %s", event.Name)
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select {
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case a.updateChan <- true:
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// sent a signal to 'updateLoop' goroutine
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default:
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// queue is full
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}
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}
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case err, ok := <-a.watcher.Errors:
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if !ok {
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return
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}
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log.Error("AutoHosts: %s", err)
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}
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}
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}
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// updateLoop reads static hosts from system files.
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func (a *AutoHosts) updateLoop() {
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for ok := range a.updateChan {
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if !ok {
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log.Debug("Finished AutoHosts update loop")
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return
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}
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a.updateHosts()
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}
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}
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// updateHosts - loads system hosts
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func (a *AutoHosts) updateHosts() {
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table := make(map[string][]net.IP)
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tableRev := make(map[string][]string)
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a.load(table, tableRev, a.hostsFn)
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for _, dir := range a.hostsDirs {
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fis, err := ioutil.ReadDir(dir)
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if err != nil {
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if !os.IsNotExist(err) {
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log.Error("AutoHosts: Opening directory: %s: %s", dir, err)
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}
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continue
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}
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for _, fi := range fis {
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a.load(table, tableRev, dir+"/"+fi.Name())
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}
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}
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a.lock.Lock()
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a.table = table
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a.tableReverse = tableRev
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a.lock.Unlock()
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a.notify()
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}
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