Pull request: 3538 dhcp options
Merge in DNS/adguard-home from 3538-dhcp-options to master Closes #3538. Updates #3366. Squashed commit of the following: commit 8b8cd118834aaf393fd13daf2afc9867794ee102 Author: Eugene Burkov <E.Burkov@AdGuard.COM> Date: Mon Sep 13 19:57:09 2021 +0300 dhcpd: imp tests commit 1789171283280b6934eed87137a693cd310a9c0a Author: Eugene Burkov <E.Burkov@AdGuard.COM> Date: Mon Sep 13 19:04:12 2021 +0300 dhcpd: fix ip version commit 07108a95a2026592e72cabecbf6275b6dd50c18a Author: Eugene Burkov <E.Burkov@AdGuard.COM> Date: Mon Sep 13 18:56:21 2021 +0300 all: imp log of changes commit 461441b3709bf1383abebffa4067ea89f4763d79 Author: Eugene Burkov <E.Burkov@AdGuard.COM> Date: Mon Sep 13 18:48:55 2021 +0300 dhcpd: imp code & docs, log changes commit 723f818baeadb9f0805cad96351a3b117155a103 Author: Eugene Burkov <E.Burkov@AdGuard.COM> Date: Mon Sep 13 17:27:30 2021 +0300 dhcpd: add default options commit 575e9d01cf95a564aed31d26a6cc9376850d321a Author: Eugene Burkov <E.Burkov@AdGuard.COM> Date: Wed Sep 8 13:05:01 2021 +0300 dhcpd: imp options logic
This commit is contained in:
Eugene Burkov
192
internal/dhcpd/options_unix.go
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192
internal/dhcpd/options_unix.go
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@@ -0,0 +1,192 @@
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//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
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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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"encoding/hex"
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"fmt"
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"net"
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"strconv"
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"strings"
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"github.com/AdguardTeam/golibs/errors"
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"github.com/AdguardTeam/golibs/log"
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"github.com/AdguardTeam/golibs/netutil"
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"github.com/insomniacslk/dhcp/dhcpv4"
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)
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// The aliases for DHCP option types available for explicit declaration.
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const (
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hexTyp = "hex"
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ipTyp = "ip"
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ipsTyp = "ips"
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textTyp = "text"
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)
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// parseDHCPOptionHex parses a DHCP option as a hex-encoded string. For
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// example:
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//
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// 252 hex 736f636b733a2f2f70726f78792e6578616d706c652e6f7267
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//
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func parseDHCPOptionHex(s string) (val dhcpv4.OptionValue, err error) {
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var data []byte
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data, err = hex.DecodeString(s)
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if err != nil {
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return nil, fmt.Errorf("decoding hex: %w", err)
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}
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return dhcpv4.OptionGeneric{Data: data}, nil
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}
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// parseDHCPOptionIP parses a DHCP option as a single IP address. For example:
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//
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// 6 ip 192.168.1.1
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//
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func parseDHCPOptionIP(s string) (val dhcpv4.OptionValue, err error) {
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var ip net.IP
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// All DHCPv4 options require IPv4, so don't put the 16-byte version.
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// Otherwise, the clients will receive weird data that looks like four
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// IPv4 addresses.
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//
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// See https://github.com/AdguardTeam/AdGuardHome/issues/2688.
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if ip, err = netutil.ParseIPv4(s); err != nil {
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return nil, err
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}
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return dhcpv4.IP(ip), nil
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}
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// parseDHCPOptionIPs parses a DHCP option as a comma-separates list of IP
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// addresses. For example:
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//
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// 6 ips 192.168.1.1,192.168.1.2
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//
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func parseDHCPOptionIPs(s string) (val dhcpv4.OptionValue, err error) {
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var ips dhcpv4.IPs
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var ip net.IP
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for i, ipStr := range strings.Split(s, ",") {
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// See notes in the ipDHCPOptionParserHandler.
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if ip, err = netutil.ParseIPv4(ipStr); err != nil {
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return nil, fmt.Errorf("parsing ip at index %d: %w", i, err)
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}
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ips = append(ips, ip)
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}
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return ips, nil
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}
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// parseDHCPOptionText parses a DHCP option as a simple UTF-8 encoded
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// text. For example:
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//
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// 252 text http://192.168.1.1/wpad.dat
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//
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func parseDHCPOptionText(s string) (val dhcpv4.OptionValue) {
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return dhcpv4.OptionGeneric{Data: []byte(s)}
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}
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// parseDHCPOption parses an option. See the documentation of parseDHCPOption*
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// for more info.
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func parseDHCPOption(s string) (opt dhcpv4.Option, err error) {
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defer func() { err = errors.Annotate(err, "invalid option string %q: %w", s) }()
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s = strings.TrimSpace(s)
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parts := strings.SplitN(s, " ", 3)
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if len(parts) < 3 {
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return opt, errors.Error("need at least three fields")
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}
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var code64 uint64
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code64, err = strconv.ParseUint(parts[0], 10, 8)
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if err != nil {
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return opt, fmt.Errorf("parsing option code: %w", err)
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}
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var optVal dhcpv4.OptionValue
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switch typ, val := parts[1], parts[2]; typ {
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case hexTyp:
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optVal, err = parseDHCPOptionHex(val)
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case ipTyp:
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optVal, err = parseDHCPOptionIP(val)
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case ipsTyp:
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optVal, err = parseDHCPOptionIPs(val)
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case textTyp:
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optVal = parseDHCPOptionText(val)
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default:
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return opt, fmt.Errorf("unknown option type %q", typ)
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}
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if err != nil {
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return opt, err
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}
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return dhcpv4.Option{
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Code: dhcpv4.GenericOptionCode(code64),
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Value: optVal,
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}, nil
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}
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// prepareOptions builds the set of DHCP options according to host requirements
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// document and values from conf.
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func prepareOptions(conf V4ServerConf) (opts dhcpv4.Options) {
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opts = dhcpv4.Options{
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// Set default values for host configuration parameters listed
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// in Appendix A of RFC-2131. Those parameters, if requested by
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// client, should be returned with values defined by Host
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// Requirements Document.
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//
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// See https://datatracker.ietf.org/doc/html/rfc2131#appendix-A.
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//
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// See also https://datatracker.ietf.org/doc/html/rfc1122,
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// https://datatracker.ietf.org/doc/html/rfc1123, and
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// https://datatracker.ietf.org/doc/html/rfc2132.
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// IP-Layer Per Host
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dhcpv4.OptionNonLocalSourceRouting.Code(): []byte{0},
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// Set the current recommended default time to live for the
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// Internet Protocol which is 64, see
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// https://datatracker.ietf.org/doc/html/rfc1700.
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dhcpv4.OptionDefaultIPTTL.Code(): []byte{64},
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// IP-Layer Per Interface
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dhcpv4.OptionPerformMaskDiscovery.Code(): []byte{0},
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dhcpv4.OptionMaskSupplier.Code(): []byte{0},
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dhcpv4.OptionPerformRouterDiscovery.Code(): []byte{1},
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// The all-routers address is preferred wherever possible, see
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// https://datatracker.ietf.org/doc/html/rfc1256#section-5.1.
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dhcpv4.OptionRouterSolicitationAddress.Code(): net.IPv4allrouter.To4(),
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dhcpv4.OptionBroadcastAddress.Code(): net.IPv4bcast.To4(),
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// Link-Layer Per Interface
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dhcpv4.OptionTrailerEncapsulation.Code(): []byte{0},
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dhcpv4.OptionEthernetEncapsulation.Code(): []byte{0},
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// TCP Per Host
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dhcpv4.OptionTCPKeepaliveInterval.Code(): dhcpv4.Duration(0).ToBytes(),
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dhcpv4.OptionTCPKeepaliveGarbage.Code(): []byte{0},
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// Values From Configuration
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dhcpv4.OptionRouter.Code(): netutil.CloneIP(conf.subnet.IP),
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dhcpv4.OptionSubnetMask.Code(): dhcpv4.IPMask(conf.subnet.Mask).ToBytes(),
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}
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// Set values for explicitly configured options.
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for i, o := range conf.Options {
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opt, err := parseDHCPOption(o)
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if err != nil {
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log.Error("dhcpv4: bad option string at index %d: %s", i, err)
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continue
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}
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opts.Update(opt)
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}
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return opts
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}
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