aa7818e1d3
* Update to avoid pseudo-random number This PR update the usage of rand so that non-global seed is used. Signed-off-by: Yong Tang <yong.tang.github@outlook.com> * Add concurrency-safe random source See https://stackoverflow.com/questions/48958886/how-to-create-a-thread-safe-rand-source Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
87 lines
1.7 KiB
Go
87 lines
1.7 KiB
Go
package loop
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import (
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"net"
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"strconv"
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"time"
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"github.com/coredns/caddy"
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"github.com/coredns/coredns/core/dnsserver"
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"github.com/coredns/coredns/plugin"
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"github.com/coredns/coredns/plugin/pkg/dnsutil"
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"github.com/coredns/coredns/plugin/pkg/rand"
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)
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func init() { plugin.Register("loop", setup) }
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func setup(c *caddy.Controller) error {
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l, err := parse(c)
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if err != nil {
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return plugin.Error("loop", err)
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}
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dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
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l.Next = next
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return l
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})
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// Send query to ourselves and see if it end up with us again.
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c.OnStartup(func() error {
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// Another Go function, otherwise we block startup and can't send the packet.
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go func() {
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deadline := time.Now().Add(30 * time.Second)
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conf := dnsserver.GetConfig(c)
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lh := conf.ListenHosts[0]
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addr := net.JoinHostPort(lh, conf.Port)
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for time.Now().Before(deadline) {
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l.setAddress(addr)
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if _, err := l.exchange(addr); err != nil {
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l.reset()
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time.Sleep(1 * time.Second)
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continue
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}
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go func() {
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time.Sleep(2 * time.Second)
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l.setDisabled()
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}()
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break
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}
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l.setDisabled()
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}()
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return nil
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})
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return nil
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}
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func parse(c *caddy.Controller) (*Loop, error) {
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i := 0
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zones := []string{"."}
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for c.Next() {
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if i > 0 {
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return nil, plugin.ErrOnce
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}
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i++
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if c.NextArg() {
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return nil, c.ArgErr()
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}
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if len(c.ServerBlockKeys) > 0 {
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zones = plugin.Host(c.ServerBlockKeys[0]).NormalizeExact()
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}
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}
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return New(zones[0]), nil
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}
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// qname returns a random name. <rand.Int()>.<rand.Int().<zone>.
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func qname(zone string) string {
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l1 := strconv.Itoa(r.Int())
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l2 := strconv.Itoa(r.Int())
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return dnsutil.Join(l1, l2, zone)
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}
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var r = rand.New(time.Now().UnixNano())
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