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Pull request: 3443 dhcp broadcast 

Merge in DNS/adguard-home from 3443-fix-wired-dhcp to master

Updates #3443.

Squashed commit of the following:

commit ec7c3b73e274ba7c05c5856cb2f4ea218ad46870
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Sep 7 18:21:07 2021 +0300

    dhcpd: imp docs & naming

commit d87c646af44d837c81aa032e82aad846bde97bc8
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Sep 7 16:56:36 2021 +0300

    dhcpd: fix build tags & log changes

commit cbd0b3c1aa0efb32aeaa9130111719ab3861e817
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Sep 7 16:26:50 2021 +0300

    dhcpd: revert 3443 & imp broadcasting
This commit is contained in:
Eugene Burkov 2021-09-07 18:33:23 +03:00
parent bdd0ca5423
commit b77ceaaf55
8 changed files with 404 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
CHANGELOG.md
View File

@ -110,6 +110,7 @@ In this release, the schema version has changed from 10 to 12.
### Fixed
- DHCP now follows RFCs more closely ([#3443]).
- Occasional panics when reading old statistics databases ([#3506]).
- `reload` service action on macOS and FreeBSD ([#3457]).
- Inaccurate using of service actions in the installation script ([#3450]).
@ -177,6 +178,7 @@ In this release, the schema version has changed from 10 to 12.
[#3417]: https://github.com/AdguardTeam/AdGuardHome/issues/3417
[#3435]: https://github.com/AdguardTeam/AdGuardHome/issues/3435
[#3437]: https://github.com/AdguardTeam/AdGuardHome/issues/3437
[#3443]: https://github.com/AdguardTeam/AdGuardHome/issues/3443
[#3450]: https://github.com/AdguardTeam/AdGuardHome/issues/3450
[#3457]: https://github.com/AdguardTeam/AdGuardHome/issues/3457
[#3506]: https://github.com/AdguardTeam/AdGuardHome/issues/3506

37
internal/dhcpd/broadcast_bsd.go Normal file
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@ -0,0 +1,37 @@
//go:build freebsd || openbsd
// +build freebsd openbsd
package dhcpd
import (
"net"
"github.com/AdguardTeam/golibs/log"
"github.com/insomniacslk/dhcp/dhcpv4"
)
// broadcast sends resp to the broadcast address specific for network interface.
func (s *v4Server) broadcast(peer net.Addr, conn net.PacketConn, resp *dhcpv4.DHCPv4) {
// peer is expected to be of type *net.UDPConn as the server4.NewServer
// initializes it.
udpPeer, ok := peer.(*net.UDPAddr)
if !ok {
log.Error("dhcpv4: peer is of unexpected type %T", peer)
return
}
// Despite the fact that server4.NewIPv4UDPConn explicitly sets socket
// options to allow broadcasting, it also binds the connection to a
// specific interface. On FreeBSD and OpenBSD conn.WriteTo causes
// errors while writing to the addresses that belong to another
// interface. So, use the broadcast address specific for the binded
// interface.
udpPeer.IP = s.conf.broadcastIP
log.Debug("dhcpv4: sending to %s: %s", peer, resp.Summary())
if _, err := conn.WriteTo(resp.ToBytes(), peer); err != nil {
log.Error("dhcpv4: conn.Write to %s failed: %s", peer, err)
}
}

87
internal/dhcpd/broadcast_bsd_test.go Normal file
View File

@ -0,0 +1,87 @@
//go:build freebsd || openbsd
// +build freebsd openbsd
package dhcpd
import (
"bytes"
"net"
"testing"
"github.com/AdguardTeam/golibs/netutil"
"github.com/insomniacslk/dhcp/dhcpv4"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
func TestV4Server_Send_broadcast(t *testing.T) {
b := &bytes.Buffer{}
var peer *net.UDPAddr
conn := &fakePacketConn{
writeTo: func(p []byte, addr net.Addr) (n int, err error) {
udpPeer, ok := addr.(*net.UDPAddr)
require.True(t, ok)
peer = cloneUDPAddr(udpPeer)
n, err = b.Write(p)
require.NoError(t, err)
return n, nil
},
}
defaultPeer := &net.UDPAddr{
IP: net.IP{1, 2, 3, 4},
// Use neither client nor server port.
Port: 1234,
}
s := &v4Server{
conf: V4ServerConf{
broadcastIP: net.IP{1, 2, 3, 255},
},
}
testCases := []struct {
name string
req *dhcpv4.DHCPv4
resp *dhcpv4.DHCPv4
}{{
name: "nak",
req: &dhcpv4.DHCPv4{
GatewayIPAddr: netutil.IPv4Zero(),
},
resp: &dhcpv4.DHCPv4{
Options: dhcpv4.OptionsFromList(
dhcpv4.OptMessageType(dhcpv4.MessageTypeNak),
),
},
}, {
name: "fully_unspecified",
req: &dhcpv4.DHCPv4{
GatewayIPAddr: netutil.IPv4Zero(),
ClientIPAddr: netutil.IPv4Zero(),
},
resp: &dhcpv4.DHCPv4{
Options: dhcpv4.OptionsFromList(
dhcpv4.OptMessageType(dhcpv4.MessageTypeOffer),
),
},
}}
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
s.send(cloneUDPAddr(defaultPeer), conn, tc.req, tc.resp)
assert.EqualValues(t, tc.resp.ToBytes(), b.Bytes())
assert.Equal(t, &net.UDPAddr{
IP: s.conf.broadcastIP,
Port: defaultPeer.Port,
Zone: defaultPeer.Zone,
}, peer)
})
b.Reset()
peer = nil
}
}

51
internal/dhcpd/broadcast_others.go Normal file
View File

@ -0,0 +1,51 @@
//go:build aix || darwin || dragonfly || linux || netbsd || solaris
// +build aix darwin dragonfly linux netbsd solaris
package dhcpd
import (
"net"
"github.com/AdguardTeam/golibs/log"
"github.com/insomniacslk/dhcp/dhcpv4"
)
// broadcast sends resp to the broadcast address specific for network interface.
func (s *v4Server) broadcast(peer net.Addr, conn net.PacketConn, resp *dhcpv4.DHCPv4) {
respData := resp.ToBytes()
log.Debug("dhcpv4: sending to %s: %s", peer, resp.Summary())
// This write to 0xffffffff reverts some behavior changes made in
// https://github.com/AdguardTeam/AdGuardHome/issues/3289. The DHCP
// server should broadcast the message to 0xffffffff but it's
// inconsistent with the actual mental model of DHCP implementation
// which requires the network interface selection to bind to.
//
// See https://github.com/AdguardTeam/AdGuardHome/issues/3480 and
// https://github.com/AdguardTeam/AdGuardHome/issues/3366.
//
// See also https://github.com/AdguardTeam/AdGuardHome/issues/3539.
if _, err := conn.WriteTo(respData, peer); err != nil {
log.Error("dhcpv4: conn.Write to %s failed: %s", peer, err)
}
// peer is expected to be of type *net.UDPConn as the server4.NewServer
// initializes it.
udpPeer, ok := peer.(*net.UDPAddr)
if !ok {
log.Error("dhcpv4: peer is of unexpected type %T", peer)
return
}
// Broadcast the message one more time using the interface-specific
// broadcast address.
udpPeer.IP = s.conf.broadcastIP
log.Debug("dhcpv4: sending to %s: %s", peer, resp.Summary())
if _, err := conn.WriteTo(respData, peer); err != nil {
log.Error("dhcpv4: conn.Write to %s failed: %s", peer, err)
}
}

96
internal/dhcpd/broadcast_others_test.go Normal file
View File

@ -0,0 +1,96 @@
//go:build aix || darwin || dragonfly || linux || netbsd || solaris
// +build aix darwin dragonfly linux netbsd solaris
package dhcpd
import (
"bytes"
"net"
"testing"
"github.com/AdguardTeam/golibs/netutil"
"github.com/insomniacslk/dhcp/dhcpv4"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
func TestV4Server_Send_broadcast(t *testing.T) {
b := &bytes.Buffer{}
var peers []*net.UDPAddr
conn := &fakePacketConn{
writeTo: func(p []byte, addr net.Addr) (n int, err error) {
udpPeer, ok := addr.(*net.UDPAddr)
require.True(t, ok)
peers = append(peers, cloneUDPAddr(udpPeer))
n, err = b.Write(p)
require.NoError(t, err)
return n, nil
},
}
defaultPeer := &net.UDPAddr{
IP: net.IP{1, 2, 3, 4},
// Use neither client nor server port.
Port: 1234,
}
s := &v4Server{
conf: V4ServerConf{
broadcastIP: net.IP{1, 2, 3, 255},
},
}
testCases := []struct {
name string
req *dhcpv4.DHCPv4
resp *dhcpv4.DHCPv4
}{{
name: "nak",
req: &dhcpv4.DHCPv4{
GatewayIPAddr: netutil.IPv4Zero(),
},
resp: &dhcpv4.DHCPv4{
Options: dhcpv4.OptionsFromList(
dhcpv4.OptMessageType(dhcpv4.MessageTypeNak),
),
},
}, {
name: "fully_unspecified",
req: &dhcpv4.DHCPv4{
GatewayIPAddr: netutil.IPv4Zero(),
ClientIPAddr: netutil.IPv4Zero(),
},
resp: &dhcpv4.DHCPv4{
Options: dhcpv4.OptionsFromList(
dhcpv4.OptMessageType(dhcpv4.MessageTypeOffer),
),
},
}}
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
s.send(cloneUDPAddr(defaultPeer), conn, tc.req, tc.resp)
// The same response is written twice.
respData := tc.resp.ToBytes()
assert.EqualValues(t, append(respData, respData...), b.Bytes())
require.Len(t, peers, 2)
assert.Equal(t, &net.UDPAddr{
IP: defaultPeer.IP,
Port: defaultPeer.Port,
}, peers[0])
assert.Equal(t, &net.UDPAddr{
IP: s.conf.broadcastIP,
Port: defaultPeer.Port,
}, peers[1])
})
b.Reset()
peers = nil
}
}

10
internal/dhcpd/dhcpd_test.go
View File

@ -10,6 +10,7 @@ import (
"time"
"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
"github.com/AdguardTeam/golibs/netutil"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
@ -136,3 +137,12 @@ func TestNormalizeLeases(t *testing.T) {
assert.Equal(t, leases[1].HWAddr, staticLeases[1].HWAddr)
assert.Equal(t, leases[2].HWAddr, dynLeases[1].HWAddr)
}
// cloneUDPAddr returns a deep copy of a.
func cloneUDPAddr(a *net.UDPAddr) (copy *net.UDPAddr) {
return &net.UDPAddr{
IP: netutil.CloneIP(a.IP),
Port: a.Port,
Zone: a.Zone,
}
}

56
internal/dhcpd/v4.go
View File

@ -928,28 +928,50 @@ func (s *v4Server) packetHandler(conn net.PacketConn, peer net.Addr, req *dhcpv4
resp.Options.Update(dhcpv4.OptMessageType(dhcpv4.MessageTypeNak))
}
// peer is expected to be of type *net.UDPConn as the server4.NewServer
// initializes it.
udpPeer, ok := peer.(*net.UDPAddr)
if !ok {
log.Error("dhcpv4: peer is of unexpected type %T", peer)
s.send(peer, conn, req, resp)
}
// send writes resp for peer to conn considering the req's fields and options
// according to RFC-2131.
//
// See https://datatracker.ietf.org/doc/html/rfc2131#section-4.1.
func (s *v4Server) send(peer net.Addr, conn net.PacketConn, req, resp *dhcpv4.DHCPv4) {
var unicast bool
if giaddr, unspec := req.GatewayIPAddr, netutil.IPv4Zero(); !giaddr.Equal(unspec) {
// Send any return messages to the server port on the BOOTP
// relay agent whose address appears in giaddr.
peer = &net.UDPAddr{
IP: giaddr,
Port: dhcpv4.ServerPort,
}
unicast = true
} else if mtype := resp.MessageType(); mtype == dhcpv4.MessageTypeNak {
// Broadcast any DHCPNAK messages to 0xffffffff.
} else if ciaddr := req.ClientIPAddr; !ciaddr.Equal(unspec) {
// Unicast DHCPOFFER and DHCPACK messages to the address in
// ciaddr.
peer = &net.UDPAddr{
IP: ciaddr,
Port: dhcpv4.ClientPort,
}
unicast = true
}
// TODO(e.burkov): Unicast the message to the actual link-layer address
// of the client if broadcast bit is not set. Perhaps, use custom
// connection when creating the server.
//
// See https://github.com/AdguardTeam/AdGuardHome/issues/3443.
if !unicast {
s.broadcast(peer, conn, resp)
return
}
// Despite the fact that server4.NewIPv4UDPConn explicitly sets socket
// options to allow broadcasting, it also binds the connection to a
// specific interface. On FreeBSD conn.WriteTo causes errors while
// writing to the addresses that belong to another interface. So, use
// the broadcast address specific for the binded interface in case
// server4.Server.Serve sets it to net.IPv4Bcast.
if udpPeer.IP.Equal(net.IPv4bcast) {
udpPeer.IP = s.conf.broadcastIP
}
log.Debug("dhcpv4: sending to %s: %s", peer, resp.Summary())
log.Debug("dhcpv4: sending: %s", resp.Summary())
_, err = conn.WriteTo(resp.ToBytes(), peer)
_, err := conn.WriteTo(resp.ToBytes(), peer)
if err != nil {
log.Error("dhcpv4: conn.Write to %s failed: %s", peer, err)
}

82
internal/dhcpd/v4_test.go
View File

@ -4,9 +4,11 @@
package dhcpd
import (
"bytes"
"net"
"testing"
"github.com/AdguardTeam/golibs/netutil"
"github.com/insomniacslk/dhcp/dhcpv4"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
@ -365,3 +367,83 @@ func TestNormalizeHostname(t *testing.T) {
})
}
}
// fakePacketConn is a mock implementation of net.PacketConn to simplify
// testing.
type fakePacketConn struct {
// writeTo is used to substitute net.PacketConn's WriteTo method.
writeTo func(p []byte, addr net.Addr) (n int, err error)
// net.PacketConn is embedded here simply to make *fakePacketConn a
// net.PacketConn without actually implementing all methods.
net.PacketConn
}
// WriteTo implements net.PacketConn interface for *fakePacketConn.
func (fc *fakePacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
return fc.writeTo(p, addr)
}
func TestV4Server_Send_unicast(t *testing.T) {
b := &bytes.Buffer{}
var peer *net.UDPAddr
conn := &fakePacketConn{
writeTo: func(p []byte, addr net.Addr) (n int, err error) {
udpPeer, ok := addr.(*net.UDPAddr)
require.True(t, ok)
peer = cloneUDPAddr(udpPeer)
n, err = b.Write(p)
require.NoError(t, err)
return n, nil
},
}
defaultPeer := &net.UDPAddr{
IP: net.IP{1, 2, 3, 4},
// Use neither client nor server port.
Port: 1234,
}
defaultResp := &dhcpv4.DHCPv4{
OpCode: dhcpv4.OpcodeBootReply,
}
s := &v4Server{}
testCases := []struct {
name string
req *dhcpv4.DHCPv4
wantPeer net.Addr
}{{
name: "relay_agent",
req: &dhcpv4.DHCPv4{
GatewayIPAddr: defaultPeer.IP,
},
wantPeer: &net.UDPAddr{
IP: defaultPeer.IP,
Port: dhcpv4.ServerPort,
},
}, {
name: "known_client",
req: &dhcpv4.DHCPv4{
GatewayIPAddr: netutil.IPv4Zero(),
ClientIPAddr: net.IP{2, 3, 4, 5},
},
wantPeer: &net.UDPAddr{
IP: net.IP{2, 3, 4, 5},
Port: dhcpv4.ClientPort,
},
}}
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
s.send(defaultPeer, conn, tc.req, defaultResp)
assert.EqualValues(t, defaultResp.ToBytes(), b.Bytes())
assert.Equal(t, tc.wantPeer, peer)
})
b.Reset()
peer = nil
}
}