Pull request: 3225 bsd dhcp

Merge in DNS/adguard-home from 3225-bsd-dhcp to master Closes #3225. Closes #3417. Squashed commit of the following: commit e7ea691824c7ebc8cafd8c9e206679346cbc8592 Author: Eugene Burkov <e.burkov@adguard.com> Date: Thu Aug 12 17:02:02 2021 +0300 all: imp code, docs commit 5b598fc18a9b69a0256569f4c691bb6a2193dfbd Author: Eugene Burkov <e.burkov@adguard.com> Date: Thu Aug 12 16:28:12 2021 +0300 all: mv logic, imp code, docs, log changes commit e3e1577a668fe3e5c61d075c390e4bd7268181ba Author: Eugene Burkov <e.burkov@adguard.com> Date: Thu Aug 12 14:15:10 2021 +0300 dhcpd: imp checkother commit 3cc8b058195c30a7ef0b7741ee8463270d9e47ff Author: Eugene Burkov <e.burkov@adguard.com> Date: Wed Aug 11 13:20:18 2021 +0300 all: imp bsd support
2021-08-12 17:33:53 +03:00
parent 00f2927663
commit 506b459842
21 changed files with 522 additions and 272 deletions
--- a/internal/aghnet/interfaces.go
+++ b/internal/aghnet/interfaces.go
@@ -0,0 +1,118 @@
+package aghnet
+
+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)
+}
+
+// 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
+}
+
+// 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
+	for n = 1; n <= maxAttempts; n++ {
+		addrs, err = IfaceIPAddrs(iface, ipv)
+		if err != nil {
+			return nil, fmt.Errorf("getting ip addrs: %w", err)
+		}
+
+		if len(addrs) > 0 {
+			break
+		}
+
+		log.Debug("dhcpv%d: attempt %d: no ip addresses", ipv, n)
+
+		time.Sleep(backoff)
+	}
+
+	switch len(addrs) {
+	case 0:
+		// Don't return errors in case the users want to try and enable
+		// the DHCP server later.
+		t := time.Duration(n) * backoff
+		log.Error("dhcpv%d: no ip for iface after %d attempts and %s", ipv, n, t)
+
+		return nil, nil
+	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])
+	default:
+		// Go on.
+	}
+
+	log.Debug("dhcpv%d: got addresses %s after %d attempts", ipv, addrs, n)
+
+	return addrs, nil
+}