Pull request: all: fix lint and naming issues vol. 2
Merge in DNS/adguard-home from 2276-fix-lint-2 to master Updates #2276. Squashed commit of the following: commit 24760b9586bb31be134ef9518dbece485560b1a0 Author: Ainar Garipov <A.Garipov@AdGuard.COM> Date: Mon Dec 7 14:39:50 2020 +0300 all: fix lint and naming issues vol. 2
This commit is contained in:
Ainar Garipov
282
internal/dhcpd/checkother.go
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282
internal/dhcpd/checkother.go
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// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
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package dhcpd
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import (
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"bytes"
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"fmt"
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"net"
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"os"
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"runtime"
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"time"
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"github.com/AdguardTeam/AdGuardHome/internal/dhcpd/nclient4"
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"github.com/AdguardTeam/golibs/log"
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"github.com/insomniacslk/dhcp/dhcpv4"
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"github.com/insomniacslk/dhcp/dhcpv6"
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"github.com/insomniacslk/dhcp/dhcpv6/nclient6"
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"github.com/insomniacslk/dhcp/iana"
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)
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// CheckIfOtherDHCPServersPresentV4 sends a DHCP request to the specified network interface,
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// and waits for a response for a period defined by defaultDiscoverTime
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func CheckIfOtherDHCPServersPresentV4(ifaceName string) (bool, error) {
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iface, err := net.InterfaceByName(ifaceName)
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if err != nil {
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return false, fmt.Errorf("couldn't find interface by name %s: %w", ifaceName, err)
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}
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ifaceIPNet, err := ifaceIPAddrs(iface, ipVersion4)
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if err != nil {
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return false, fmt.Errorf("getting ipv4 addrs for iface %s: %w", ifaceName, err)
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}
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if len(ifaceIPNet) == 0 {
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return false, fmt.Errorf("interface %s has no ipv4 addresses", ifaceName)
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}
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// TODO(a.garipov): Find out what this is about. Perhaps this
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// information is outdated or at least incomplete.
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if runtime.GOOS == "darwin" {
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return false, fmt.Errorf("can't find DHCP server: not supported on macOS")
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}
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srcIP := ifaceIPNet[0]
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src := net.JoinHostPort(srcIP.String(), "68")
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dst := "255.255.255.255:67"
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hostname, _ := os.Hostname()
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req, err := dhcpv4.NewDiscovery(iface.HardwareAddr)
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if err != nil {
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return false, fmt.Errorf("dhcpv4.NewDiscovery: %w", err)
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}
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req.Options.Update(dhcpv4.OptClientIdentifier(iface.HardwareAddr))
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req.Options.Update(dhcpv4.OptHostName(hostname))
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// resolve 0.0.0.0:68
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udpAddr, err := net.ResolveUDPAddr("udp4", src)
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if err != nil {
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return false, fmt.Errorf("couldn't resolve UDP address %s: %w", src, err)
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}
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if !udpAddr.IP.To4().Equal(srcIP) {
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return false, fmt.Errorf("resolved UDP address is not %s: %w", src, err)
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}
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// resolve 255.255.255.255:67
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dstAddr, err := net.ResolveUDPAddr("udp4", dst)
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if err != nil {
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return false, fmt.Errorf("couldn't resolve UDP address %s: %w", dst, err)
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}
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// bind to 0.0.0.0:68
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log.Tracef("Listening to udp4 %+v", udpAddr)
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c, err := nclient4.NewRawUDPConn(ifaceName, 68)
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if err != nil {
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return false, fmt.Errorf("couldn't listen on :68: %w", err)
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}
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if c != nil {
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defer c.Close()
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}
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// send to 255.255.255.255:67
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_, err = c.WriteTo(req.ToBytes(), dstAddr)
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if err != nil {
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return false, fmt.Errorf("couldn't send a packet to %s: %w", dst, err)
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}
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for {
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ok, next, err := tryConn4(req, c, iface)
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if next {
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if err != nil {
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log.Debug("dhcpv4: trying a connection: %s", err)
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}
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continue
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}
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if err != nil {
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return false, err
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}
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return ok, nil
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}
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}
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// TODO(a.garipov): Refactor further. Inspect error handling, remove parameter
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// next, address the TODO, merge with tryConn6, etc.
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func tryConn4(req *dhcpv4.DHCPv4, c net.PacketConn, iface *net.Interface) (ok, next bool, err error) {
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// TODO: replicate dhclient's behavior of retrying several times with
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// progressively longer timeouts.
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log.Tracef("dhcpv4: waiting %v for an answer", defaultDiscoverTime)
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b := make([]byte, 1500)
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err = c.SetDeadline(time.Now().Add(defaultDiscoverTime))
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if err != nil {
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return false, false, fmt.Errorf("setting deadline: %w", err)
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}
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n, _, err := c.ReadFrom(b)
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if err != nil {
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if isTimeout(err) {
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log.Debug("dhcpv4: didn't receive dhcp response")
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return false, false, nil
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}
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return false, false, fmt.Errorf("receiving packet: %w", err)
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}
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log.Tracef("dhcpv4: received packet, %d bytes", n)
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response, err := dhcpv4.FromBytes(b[:n])
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if err != nil {
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log.Debug("dhcpv4: encoding: %s", err)
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return false, true, err
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}
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log.Debug("dhcpv4: received message from server: %s", response.Summary())
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if !(response.OpCode == dhcpv4.OpcodeBootReply &&
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response.HWType == iana.HWTypeEthernet &&
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bytes.Equal(response.ClientHWAddr, iface.HardwareAddr) &&
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bytes.Equal(response.TransactionID[:], req.TransactionID[:]) &&
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response.Options.Has(dhcpv4.OptionDHCPMessageType)) {
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log.Debug("dhcpv4: received message from server doesn't match our request")
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return false, true, nil
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}
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log.Tracef("dhcpv4: the packet is from an active dhcp server")
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return true, false, nil
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}
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// CheckIfOtherDHCPServersPresentV6 sends a DHCP request to the specified network interface,
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// and waits for a response for a period defined by defaultDiscoverTime
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func CheckIfOtherDHCPServersPresentV6(ifaceName string) (bool, error) {
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iface, err := net.InterfaceByName(ifaceName)
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if err != nil {
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return false, fmt.Errorf("dhcpv6: net.InterfaceByName: %s: %w", ifaceName, err)
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}
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ifaceIPNet, err := ifaceIPAddrs(iface, ipVersion6)
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if err != nil {
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return false, fmt.Errorf("getting ipv6 addrs for iface %s: %w", ifaceName, err)
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}
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if len(ifaceIPNet) == 0 {
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return false, fmt.Errorf("interface %s has no ipv6 addresses", ifaceName)
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}
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srcIP := ifaceIPNet[0]
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src := net.JoinHostPort(srcIP.String(), "546")
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dst := "[ff02::1:2]:547"
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req, err := dhcpv6.NewSolicit(iface.HardwareAddr)
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if err != nil {
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return false, fmt.Errorf("dhcpv6: dhcpv6.NewSolicit: %w", err)
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}
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udpAddr, err := net.ResolveUDPAddr("udp6", src)
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if err != nil {
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return false, fmt.Errorf("dhcpv6: Couldn't resolve UDP address %s: %w", src, err)
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}
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if !udpAddr.IP.To16().Equal(srcIP) {
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return false, fmt.Errorf("dhcpv6: Resolved UDP address is not %s: %w", src, err)
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}
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dstAddr, err := net.ResolveUDPAddr("udp6", dst)
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if err != nil {
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return false, fmt.Errorf("dhcpv6: Couldn't resolve UDP address %s: %w", dst, err)
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}
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log.Debug("DHCPv6: Listening to udp6 %+v", udpAddr)
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c, err := nclient6.NewIPv6UDPConn(ifaceName, dhcpv6.DefaultClientPort)
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if err != nil {
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return false, fmt.Errorf("dhcpv6: Couldn't listen on :546: %w", err)
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}
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if c != nil {
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defer c.Close()
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}
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_, err = c.WriteTo(req.ToBytes(), dstAddr)
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if err != nil {
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return false, fmt.Errorf("dhcpv6: Couldn't send a packet to %s: %w", dst, err)
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}
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for {
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ok, next, err := tryConn6(req, c)
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if next {
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if err != nil {
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log.Debug("dhcpv6: trying a connection: %s", err)
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}
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continue
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}
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if err != nil {
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return false, err
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}
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return ok, nil
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}
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}
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// TODO(a.garipov): See the comment on tryConn4. Sigh…
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func tryConn6(req *dhcpv6.Message, c net.PacketConn) (ok, next bool, err error) {
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// TODO: replicate dhclient's behavior of retrying several times with
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// progressively longer timeouts.
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log.Tracef("dhcpv6: waiting %v for an answer", defaultDiscoverTime)
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b := make([]byte, 4096)
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err = c.SetDeadline(time.Now().Add(defaultDiscoverTime))
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if err != nil {
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return false, false, fmt.Errorf("setting deadline: %w", err)
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}
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n, _, err := c.ReadFrom(b)
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if err != nil {
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if isTimeout(err) {
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log.Debug("dhcpv6: didn't receive dhcp response")
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return false, false, nil
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}
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return false, false, fmt.Errorf("receiving packet: %w", err)
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}
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log.Tracef("dhcpv6: received packet, %d bytes", n)
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response, err := dhcpv6.FromBytes(b[:n])
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if err != nil {
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log.Debug("dhcpv6: encoding: %s", err)
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return false, true, err
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}
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log.Debug("dhcpv6: received message from server: %s", response.Summary())
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cid := req.Options.ClientID()
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msg, err := response.GetInnerMessage()
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if err != nil {
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log.Debug("dhcpv6: resp.GetInnerMessage(): %s", err)
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return false, true, err
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}
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rcid := msg.Options.ClientID()
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if !(response.Type() == dhcpv6.MessageTypeAdvertise &&
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msg.TransactionID == req.TransactionID &&
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rcid != nil &&
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cid.Equal(*rcid)) {
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log.Debug("dhcpv6: received message from server doesn't match our request")
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return false, true, nil
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}
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log.Tracef("dhcpv6: the packet is from an active dhcp server")
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return true, false, nil
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}
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