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Pull request: dhcpd: wait for interfaces' ip addresses to appear
Merge in DNS/adguard-home from 2304-dncp-backoff to master Updates #2304. Squashed commit of the following: commit c9bff8b Author: Ainar Garipov <A.Garipov@AdGuard.COM> Date: Fri Nov 27 14:08:03 2020 +0300 dhcpd: try for 5s instead of 10s commit 983cf47 Author: Ainar Garipov <A.Garipov@AdGuard.COM> Date: Wed Nov 25 19:58:41 2020 +0300 dhcpd: wait for interfaces' ip addresses to appear
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,123 @@ | ||
| package dhcpd | ||
|
|
||
| import ( | ||
| "fmt" | ||
| "net" | ||
| "time" | ||
|
|
||
| "github.com/AdguardTeam/golibs/log" | ||
| ) | ||
|
|
||
| // ipVersion is a documentational alias for int. Use it when the integer means | ||
| // IP version. | ||
| type ipVersion = int | ||
|
|
||
| // IP version constants. | ||
| const ( | ||
| ipVersion4 ipVersion = 4 | ||
| ipVersion6 ipVersion = 6 | ||
| ) | ||
|
|
||
| // netIface is the interface for network interface methods. | ||
| type netIface interface { | ||
| Addrs() ([]net.Addr, error) | ||
| } | ||
|
|
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| // ifaceIPAddrs returns the interface's IP addresses. | ||
| func ifaceIPAddrs(iface netIface, ipv ipVersion) (ips []net.IP, err error) { | ||
| addrs, err := iface.Addrs() | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| for _, a := range addrs { | ||
| var ip net.IP | ||
| switch a := a.(type) { | ||
| case *net.IPAddr: | ||
| ip = a.IP | ||
| case *net.IPNet: | ||
| ip = a.IP | ||
| default: | ||
| continue | ||
| } | ||
|
|
||
| // Assume that net.(*Interface).Addrs can only return valid IPv4 | ||
| // and IPv6 addresses. Thus, if it isn't an IPv4 address, it | ||
| // must be an IPv6 one. | ||
| switch ipv { | ||
| case ipVersion4: | ||
| if ip4 := ip.To4(); ip4 != nil { | ||
| ips = append(ips, ip4) | ||
| } | ||
| case ipVersion6: | ||
| if ip6 := ip.To4(); ip6 == nil { | ||
| ips = append(ips, ip) | ||
| } | ||
| default: | ||
| return nil, fmt.Errorf("invalid ip version %d", ipv) | ||
| } | ||
| } | ||
|
|
||
| return ips, nil | ||
| } | ||
|
|
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| // Currently used defaults for ifaceDNSAddrs. | ||
| const ( | ||
| defaultMaxAttempts int = 10 | ||
|
|
||
| defaultBackoff time.Duration = 500 * time.Millisecond | ||
| ) | ||
|
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| // ifaceDNSIPAddrs returns IP addresses of the interface suitable to send to | ||
| // clients as DNS addresses. If err is nil, addrs contains either no addresses | ||
| // or at least two. | ||
| // | ||
| // It makes up to maxAttempts attempts to get the addresses if there are none, | ||
| // each time using the provided backoff. Sometimes an interface needs a few | ||
| // seconds to really ititialize. | ||
| // | ||
| // See https://github.com/AdguardTeam/AdGuardHome/issues/2304. | ||
| func ifaceDNSIPAddrs( | ||
| iface netIface, | ||
| ipv ipVersion, | ||
| maxAttempts int, | ||
| backoff time.Duration, | ||
| ) (addrs []net.IP, err error) { | ||
| var n int | ||
| waitForIP: | ||
| for n = 1; n <= maxAttempts; n++ { | ||
| addrs, err = ifaceIPAddrs(iface, ipv) | ||
| if err != nil { | ||
| return nil, fmt.Errorf("getting ip addrs: %w", err) | ||
| } | ||
|
|
||
| switch len(addrs) { | ||
| case 0: | ||
| log.Debug("dhcpv%d: attempt %d: no ip addresses", ipv, n) | ||
|
|
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| time.Sleep(backoff) | ||
| case 1: | ||
| // Some Android devices use 8.8.8.8 if there is not | ||
| // a secondary DNS server. Fix that by setting the | ||
| // secondary DNS address to the same address. | ||
| // | ||
| // See https://github.com/AdguardTeam/AdGuardHome/issues/1708. | ||
| log.Debug("dhcpv%d: setting secondary dns ip to itself", ipv) | ||
| addrs = append(addrs, addrs[0]) | ||
|
|
||
| fallthrough | ||
| default: | ||
| break waitForIP | ||
| } | ||
| } | ||
|
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| if len(addrs) == 0 { | ||
| // Don't return errors in case the users want to try and enable | ||
| // the DHCP server later. | ||
| log.Error("dhcpv%d: no ip address for interface after %d attempts and %s", ipv, n, time.Duration(n)*backoff) | ||
| } else { | ||
| log.Debug("dhcpv%d: got addresses %s after %d attempts", ipv, addrs, n) | ||
| } | ||
|
|
||
| return addrs, nil | ||
| } |
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