diff options
| -rw-r--r-- | dhcpv4/dhcpv4.go | 6 | ||||
| -rw-r--r-- | dhcpv4/nclient4/client.go | 412 | ||||
| -rw-r--r-- | dhcpv4/nclient4/client_test.go | 326 | ||||
| -rw-r--r-- | dhcpv4/nclient4/conn_linux.go | 173 | ||||
| -rw-r--r-- | dhcpv4/nclient4/ipv4.go | 376 | ||||
| -rw-r--r-- | dhcpv4/server4/server.go | 117 | ||||
| -rw-r--r-- | dhcpv4/server4/server_test.go | 77 |
7 files changed, 1366 insertions, 121 deletions
diff --git a/dhcpv4/dhcpv4.go b/dhcpv4/dhcpv4.go index 0373764..f74ed40 100644 --- a/dhcpv4/dhcpv4.go +++ b/dhcpv4/dhcpv4.go @@ -225,13 +225,17 @@ func NewRequestFromOffer(offer *DHCPv4, modifiers ...Modifier) (*DHCPv4, error) // find server IP address serverIP := offer.ServerIdentifier() if serverIP == nil { - return nil, errors.New("Missing Server IP Address in DHCP Offer") + if offer.ServerIPAddr == nil || offer.ServerIPAddr.IsUnspecified() { + return nil, fmt.Errorf("missing Server IP Address in DHCP Offer") + } + serverIP = offer.ServerIPAddr } return New(PrependModifiers(modifiers, WithReply(offer), WithMessageType(MessageTypeRequest), WithServerIP(serverIP), + WithClientIP(offer.ClientIPAddr), WithOption(OptRequestedIPAddress(offer.YourIPAddr)), WithOption(OptServerIdentifier(serverIP)), )...) diff --git a/dhcpv4/nclient4/client.go b/dhcpv4/nclient4/client.go new file mode 100644 index 0000000..3c97a60 --- /dev/null +++ b/dhcpv4/nclient4/client.go @@ -0,0 +1,412 @@ +// Copyright 2018 the u-root Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// +build go1.12 + +// Package nclient4 is a small, minimum-functionality client for DHCPv4. +// +// It only supports the 4-way DHCPv4 Discover-Offer-Request-Ack handshake as +// well as the Request-Ack renewal process. +package nclient4 + +import ( + "bytes" + "context" + "errors" + "fmt" + "log" + "net" + "strings" + "sync" + "sync/atomic" + "time" + + "github.com/insomniacslk/dhcp/dhcpv4" +) + +const ( + defaultTimeout = 5 * time.Second + defaultRetries = 3 + defaultBufferCap = 5 + maxMessageSize = 1500 + + // ClientPort is the port that DHCP clients listen on. + ClientPort = 68 + + // ServerPort is the port that DHCP servers and relay agents listen on. + ServerPort = 67 +) + +var ( + // DefaultServers is the address of all link-local DHCP servers and + // relay agents. + DefaultServers = &net.UDPAddr{ + IP: net.IPv4bcast, + Port: ServerPort, + } +) + +var ( + // ErrNoResponse is returned when no response packet is received. + ErrNoResponse = errors.New("no matching response packet received") +) + +// pendingCh is a channel associated with a pending TransactionID. +type pendingCh struct { + // SendAndRead closes done to indicate that it wishes for no more + // messages for this particular XID. + done <-chan struct{} + + // ch is used by the receive loop to distribute DHCP messages. + ch chan<- *dhcpv4.DHCPv4 +} + +// Client is an IPv4 DHCP client. +type Client struct { + ifaceHWAddr net.HardwareAddr + conn net.PacketConn + timeout time.Duration + retry int + + // bufferCap is the channel capacity for each TransactionID. + bufferCap int + + // serverAddr is the UDP address to send all packets to. + // + // This may be an actual broadcast address, or a unicast address. + serverAddr *net.UDPAddr + + // closed is an atomic bool set to 1 when done is closed. + closed uint32 + + // done is closed to unblock the receive loop. + done chan struct{} + + // wg protects any spawned goroutines, namely the receiveLoop. + wg sync.WaitGroup + + pendingMu sync.Mutex + // pending stores the distribution channels for each pending + // TransactionID. receiveLoop uses this map to determine which channel + // to send a new DHCP message to. + pending map[dhcpv4.TransactionID]*pendingCh +} + +// New returns a client usable with an unconfigured interface. +func New(ifaceName string, ifaceHWAddr net.HardwareAddr, opts ...ClientOpt) (*Client, error) { + c := NewWithConn(nil, ifaceHWAddr, opts...) + + // Do this after so that a caller can still use a WithConn to override + // the connection. + if c.conn == nil { + pc, err := NewRawUDPConn(ifaceName, ClientPort) + if err != nil { + return nil, err + } + c.conn = pc + } + return c, nil +} + +// NewWithConn creates a new DHCP client that sends and receives packets on the +// given interface. +func NewWithConn(conn net.PacketConn, ifaceHWAddr net.HardwareAddr, opts ...ClientOpt) *Client { + c := &Client{ + ifaceHWAddr: ifaceHWAddr, + timeout: defaultTimeout, + retry: defaultRetries, + serverAddr: DefaultServers, + bufferCap: defaultBufferCap, + conn: conn, + + done: make(chan struct{}), + pending: make(map[dhcpv4.TransactionID]*pendingCh), + } + + for _, opt := range opts { + opt(c) + } + + c.wg.Add(1) + go c.receiveLoop() + return c +} + +// Close closes the underlying connection. +func (c *Client) Close() error { + // Make sure not to close done twice. + if !atomic.CompareAndSwapUint32(&c.closed, 0, 1) { + return nil + } + + err := c.conn.Close() + + // Closing c.done sets off a chain reaction: + // + // Any SendAndRead unblocks trying to receive more messages, which + // means rem() gets called. + // + // rem() should be unblocking receiveLoop if it is blocked. + // + // receiveLoop should then exit gracefully. + close(c.done) + + // Wait for receiveLoop to stop. + c.wg.Wait() + + return err +} + +func isErrClosing(err error) bool { + // Unfortunately, the epoll-connection-closed error is internal to the + // net library. + return strings.Contains(err.Error(), "use of closed network connection") +} + +func (c *Client) receiveLoop() { + defer c.wg.Done() + for { + // TODO: Clients can send a "max packet size" option in their + // packets, IIRC. Choose a reasonable size and set it. + b := make([]byte, maxMessageSize) + n, _, err := c.conn.ReadFrom(b) + if err != nil { + if !isErrClosing(err) { + log.Printf("error reading from UDP connection: %v", err) + } + return + } + + msg, err := dhcpv4.FromBytes(b[:n]) + if err != nil { + // Not a valid DHCP packet; keep listening. + continue + } + + if msg.OpCode != dhcpv4.OpcodeBootReply { + // Not a response message. + continue + } + + // This is a somewhat non-standard check, by the looks + // of RFC 2131. It should work as long as the DHCP + // server is spec-compliant for the HWAddr field. + if c.ifaceHWAddr != nil && !bytes.Equal(c.ifaceHWAddr, msg.ClientHWAddr) { + // Not for us. + continue + } + + c.pendingMu.Lock() + p, ok := c.pending[msg.TransactionID] + if ok { + select { + case <-p.done: + close(p.ch) + delete(c.pending, msg.TransactionID) + + // This send may block. + case p.ch <- msg: + } + } + c.pendingMu.Unlock() + } +} + +// ClientOpt is a function that configures the Client. +type ClientOpt func(*Client) + +// WithTimeout configures the retransmission timeout. +// +// Default is 5 seconds. +func WithTimeout(d time.Duration) ClientOpt { + return func(c *Client) { + c.timeout = d + } +} + +func withBufferCap(n int) ClientOpt { + return func(c *Client) { + c.bufferCap = n + } +} + +// WithRetry configures the number of retransmissions to attempt. +// +// Default is 3. +func WithRetry(r int) ClientOpt { + return func(c *Client) { + c.retry = r + } +} + +// WithConn configures the packet connection to use. +func WithConn(conn net.PacketConn) ClientOpt { + return func(c *Client) { + c.conn = conn + } +} + +// WithServerAddr configures the address to send messages to. +func WithServerAddr(n *net.UDPAddr) ClientOpt { + return func(c *Client) { + c.serverAddr = n + } +} + +// Matcher matches DHCP packets. +type Matcher func(*dhcpv4.DHCPv4) bool + +// IsMessageType returns a matcher that checks for the message type. +// +// If t is MessageTypeNone, all packets are matched. +func IsMessageType(t dhcpv4.MessageType) Matcher { + return func(p *dhcpv4.DHCPv4) bool { + return p.MessageType() == t || t == dhcpv4.MessageTypeNone + } +} + +// DiscoverOffer sends a DHCPDiscover message and returns the first valid offer +// received. +func (c *Client) DiscoverOffer(ctx context.Context, modifiers ...dhcpv4.Modifier) (*dhcpv4.DHCPv4, error) { + // RFC 2131, Section 4.4.1, Table 5 details what a DISCOVER packet should + // contain. + discover, err := dhcpv4.NewDiscovery(c.ifaceHWAddr, dhcpv4.PrependModifiers(modifiers, + dhcpv4.WithOption(dhcpv4.OptMaxMessageSize(maxMessageSize)))...) + if err != nil { + return nil, err + } + return c.SendAndRead(ctx, c.serverAddr, discover, IsMessageType(dhcpv4.MessageTypeOffer)) +} + +// Request completes the 4-way Discover-Offer-Request-Ack handshake. +// +// Note that modifiers will be applied *both* to Discover and Request packets. +func (c *Client) Request(ctx context.Context, modifiers ...dhcpv4.Modifier) (offer, ack *dhcpv4.DHCPv4, err error) { + offer, err = c.DiscoverOffer(ctx, modifiers...) + if err != nil { + return nil, nil, err + } + + // TODO(chrisko): should this be unicast to the server? + req, err := dhcpv4.NewRequestFromOffer(offer, dhcpv4.PrependModifiers(modifiers, + dhcpv4.WithOption(dhcpv4.OptMaxMessageSize(maxMessageSize)))...) + if err != nil { + return nil, nil, err + } + ack, err = c.SendAndRead(ctx, c.serverAddr, req, nil) + if err != nil { + return nil, nil, err + } + return offer, ack, nil +} + +// send sends p to destination and returns a response channel. +// +// Responses will be matched by transaction ID and ClientHWAddr. +// +// The returned lambda function must be called after all desired responses have +// been received in order to return the Transaction ID to the usable pool. +func (c *Client) send(dest *net.UDPAddr, msg *dhcpv4.DHCPv4) (resp <-chan *dhcpv4.DHCPv4, cancel func(), err error) { + c.pendingMu.Lock() + if _, ok := c.pending[msg.TransactionID]; ok { + c.pendingMu.Unlock() + return nil, nil, fmt.Errorf("transaction ID %s already in use", msg.TransactionID) + } + + ch := make(chan *dhcpv4.DHCPv4, c.bufferCap) + done := make(chan struct{}) + c.pending[msg.TransactionID] = &pendingCh{done: done, ch: ch} + c.pendingMu.Unlock() + + cancel = func() { + // Why can't we just close ch here? + // + // Because receiveLoop may potentially be blocked trying to + // send on ch. We gotta unblock it first, and then we can take + // the lock and remove the XID from the pending transaction + // map. + close(done) + + c.pendingMu.Lock() + if p, ok := c.pending[msg.TransactionID]; ok { + close(p.ch) + delete(c.pending, msg.TransactionID) + } + c.pendingMu.Unlock() + } + + if _, err := c.conn.WriteTo(msg.ToBytes(), dest); err != nil { + cancel() + return nil, nil, fmt.Errorf("error writing packet to connection: %v", err) + } + return ch, cancel, nil +} + +// This error should never be visible to users. +// It is used only to increase the timeout in retryFn. +var errDeadlineExceeded = errors.New("INTERNAL ERROR: deadline exceeded") + +// SendAndRead sends a packet p to a destination dest and waits for the first +// response matching `match` as well as its Transaction ID and ClientHWAddr. +// +// If match is nil, the first packet matching the Transaction ID and +// ClientHWAddr is returned. +func (c *Client) SendAndRead(ctx context.Context, dest *net.UDPAddr, p *dhcpv4.DHCPv4, match Matcher) (*dhcpv4.DHCPv4, error) { + var response *dhcpv4.DHCPv4 + err := c.retryFn(func(timeout time.Duration) error { + ch, rem, err := c.send(dest, p) + if err != nil { + return err + } + defer rem() + + for { + select { + case <-c.done: + return ErrNoResponse + + case <-time.After(timeout): + return errDeadlineExceeded + + case <-ctx.Done(): + return ctx.Err() + + case packet := <-ch: + if match == nil || match(packet) { + response = packet + return nil + } + } + } + }) + if err == errDeadlineExceeded { + return nil, ErrNoResponse + } + if err != nil { + return nil, err + } + return response, nil +} + +func (c *Client) retryFn(fn func(timeout time.Duration) error) error { + timeout := c.timeout + + // Each retry takes the amount of timeout at worst. + for i := 0; i < c.retry || c.retry < 0; i++ { + switch err := fn(timeout); err { + case nil: + // Got it! + return nil + + case errDeadlineExceeded: + // Double timeout, then retry. + timeout *= 2 + + default: + return err + } + } + + return errDeadlineExceeded +} diff --git a/dhcpv4/nclient4/client_test.go b/dhcpv4/nclient4/client_test.go new file mode 100644 index 0000000..d3ea68b --- /dev/null +++ b/dhcpv4/nclient4/client_test.go @@ -0,0 +1,326 @@ +// Copyright 2018 the u-root Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// +build go1.12 + +package nclient4 + +import ( + "bytes" + "context" + "fmt" + "net" + "sync" + "testing" + "time" + + "github.com/hugelgupf/socketpair" + "github.com/insomniacslk/dhcp/dhcpv4" + "github.com/insomniacslk/dhcp/dhcpv4/server4" +) + +type handler struct { + mu sync.Mutex + received []*dhcpv4.DHCPv4 + + // Each received packet can have more than one response (in theory, + // from different servers sending different Advertise, for example). + responses [][]*dhcpv4.DHCPv4 +} + +func (h *handler) handle(conn net.PacketConn, peer net.Addr, m *dhcpv4.DHCPv4) { + h.mu.Lock() + defer h.mu.Unlock() + + h.received = append(h.received, m) + + if len(h.responses) > 0 { + for _, resp := range h.responses[0] { + conn.WriteTo(resp.ToBytes(), peer) + } + h.responses = h.responses[1:] + } +} + +func serveAndClient(ctx context.Context, responses [][]*dhcpv4.DHCPv4, opts ...ClientOpt) (*Client, net.PacketConn) { + // Fake PacketConn connection. + clientRawConn, serverRawConn, err := socketpair.PacketSocketPair() + if err != nil { + panic(err) + } + + clientConn := NewBroadcastUDPConn(clientRawConn, &net.UDPAddr{IP: net.IPv4zero, Port: ClientPort}) + serverConn := NewBroadcastUDPConn(serverRawConn, &net.UDPAddr{Port: ServerPort}) + + o := []ClientOpt{WithRetry(1), WithTimeout(2 * time.Second)} + o = append(o, opts...) + mc := NewWithConn(clientConn, net.HardwareAddr{0xa, 0xb, 0xc, 0xd, 0xe, 0xf}, o...) + + h := &handler{responses: responses} + s, err := server4.NewServer(nil, h.handle, server4.WithConn(serverConn)) + if err != nil { + panic(err) + } + go s.Serve() + + return mc, serverConn +} + +func ComparePacket(got *dhcpv4.DHCPv4, want *dhcpv4.DHCPv4) error { + if got == nil && got == want { + return nil + } + if (want == nil || got == nil) && (got != want) { + return fmt.Errorf("packet got %v, want %v", got, want) + } + if bytes.Compare(got.ToBytes(), want.ToBytes()) != 0 { + return fmt.Errorf("packet got %v, want %v", got, want) + } + return nil +} + +func pktsExpected(got []*dhcpv4.DHCPv4, want []*dhcpv4.DHCPv4) error { + if len(got) != len(want) { + return fmt.Errorf("got %d packets, want %d packets", len(got), len(want)) + } + + for i := range got { + if err := ComparePacket(got[i], want[i]); err != nil { + return err + } + } + return nil +} + +func newPacketWeirdHWAddr(op dhcpv4.OpcodeType, xid dhcpv4.TransactionID) *dhcpv4.DHCPv4 { + p, err := dhcpv4.New() + if err != nil { + panic(fmt.Sprintf("newpacket: %v", err)) + } + p.OpCode = op + p.TransactionID = xid + p.ClientHWAddr = net.HardwareAddr{0xa, 0xb, 0xc, 0xd, 0xe, 0xf, 1, 2, 3, 4, 5, 6} + return p +} + +func newPacket(op dhcpv4.OpcodeType, xid dhcpv4.TransactionID) *dhcpv4.DHCPv4 { + p, err := dhcpv4.New() + if err != nil { + panic(fmt.Sprintf("newpacket: %v", err)) + } + p.OpCode = op + p.TransactionID = xid + p.ClientHWAddr = net.HardwareAddr{0xa, 0xb, 0xc, 0xd, 0xe, 0xf} + return p +} + +func TestSendAndRead(t *testing.T) { + for _, tt := range []struct { + desc string + send *dhcpv4.DHCPv4 + server []*dhcpv4.DHCPv4 + + // If want is nil, we assume server[0] contains what is wanted. + want *dhcpv4.DHCPv4 + wantErr error + }{ + { + desc: "two response packets", + send: newPacket(dhcpv4.OpcodeBootRequest, [4]byte{0x33, 0x33, 0x33, 0x33}), + server: []*dhcpv4.DHCPv4{ + newPacket(dhcpv4.OpcodeBootReply, [4]byte{0x33, 0x33, 0x33, 0x33}), + newPacket(dhcpv4.OpcodeBootReply, [4]byte{0x33, 0x33, 0x33, 0x33}), + newPacket(dhcpv4.OpcodeBootReply, [4]byte{0x33, 0x33, 0x33, 0x33}), + newPacket(dhcpv4.OpcodeBootReply, [4]byte{0x33, 0x33, 0x33, 0x33}), + newPacket(dhcpv4.OpcodeBootReply, [4]byte{0x33, 0x33, 0x33, 0x33}), + }, + want: newPacket(dhcpv4.OpcodeBootReply, [4]byte{0x33, 0x33, 0x33, 0x33}), + }, + { + desc: "one response packet", + send: newPacket(dhcpv4.OpcodeBootRequest, [4]byte{0x33, 0x33, 0x33, 0x33}), + server: []*dhcpv4.DHCPv4{ + newPacket(dhcpv4.OpcodeBootReply, [4]byte{0x33, 0x33, 0x33, 0x33}), + }, + want: newPacket(dhcpv4.OpcodeBootReply, [4]byte{0x33, 0x33, 0x33, 0x33}), + }, + { + desc: "one response packet, one invalid XID, one invalid opcode, one invalid hwaddr", + send: newPacket(dhcpv4.OpcodeBootRequest, [4]byte{0x33, 0x33, 0x33, 0x33}), + server: []*dhcpv4.DHCPv4{ + newPacket(dhcpv4.OpcodeBootReply, [4]byte{0x77, 0x33, 0x33, 0x33}), + newPacket(dhcpv4.OpcodeBootRequest, [4]byte{0x33, 0x33, 0x33, 0x33}), + newPacketWeirdHWAddr(dhcpv4.OpcodeBootReply, [4]byte{0x33, 0x33, 0x33, 0x33}), + newPacket(dhcpv4.OpcodeBootReply, [4]byte{0x33, 0x33, 0x33, 0x33}), + }, + want: newPacket(dhcpv4.OpcodeBootReply, [4]byte{0x33, 0x33, 0x33, 0x33}), + }, + { + desc: "discard wrong XID", + send: newPacket(dhcpv4.OpcodeBootRequest, [4]byte{0x33, 0x33, 0x33, 0x33}), + server: []*dhcpv4.DHCPv4{ + newPacket(dhcpv4.OpcodeBootReply, [4]byte{0, 0, 0, 0}), + }, + want: nil, // Explicitly empty. + wantErr: ErrNoResponse, + }, + { + desc: "no response, timeout", + send: newPacket(dhcpv4.OpcodeBootRequest, [4]byte{0x33, 0x33, 0x33, 0x33}), + wantErr: ErrNoResponse, + }, + } { + t.Run(tt.desc, func(t *testing.T) { + // Both server and client only get 2 seconds. + ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second) + defer cancel() + + mc, _ := serveAndClient(ctx, [][]*dhcpv4.DHCPv4{tt.server}, + // Use an unbuffered channel to make sure we + // have no deadlocks. + withBufferCap(0)) + defer mc.Close() + + rcvd, err := mc.SendAndRead(context.Background(), DefaultServers, tt.send, nil) + if err != tt.wantErr { + t.Error(err) + } + + if err := ComparePacket(rcvd, tt.want); err != nil { + t.Errorf("got unexpected packets: %v", err) + } + }) + } +} + +func TestParallelSendAndRead(t *testing.T) { + pkt := newPacket(dhcpv4.OpcodeBootRequest, [4]byte{0x33, 0x33, 0x33, 0x33}) + + // Both the server and client only get 2 seconds. + ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second) + defer cancel() + + mc, _ := serveAndClient(ctx, [][]*dhcpv4.DHCPv4{}, + WithTimeout(10*time.Second), + // Use an unbuffered channel to make sure nothing blocks. + withBufferCap(0)) + defer mc.Close() + + var wg sync.WaitGroup + + wg.Add(1) + go func() { + defer wg.Done() + if _, err := mc.SendAndRead(context.Background(), DefaultServers, pkt, nil); err != ErrNoResponse { + t.Errorf("SendAndRead(%v) = %v, want %v", pkt, err, ErrNoResponse) + } + }() + + wg.Add(1) + go func() { + defer wg.Done() + + time.Sleep(4 * time.Second) + + if err := mc.Close(); err != nil { + t.Errorf("closing failed: %v", err) + } + }() + + wg.Wait() +} + +func TestReuseXID(t *testing.T) { + pkt := newPacket(dhcpv4.OpcodeBootRequest, [4]byte{0x33, 0x33, 0x33, 0x33}) + + // Both the server and client only get 2 seconds. + ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second) + defer cancel() + + mc, _ := serveAndClient(ctx, [][]*dhcpv4.DHCPv4{}) + defer mc.Close() + + if _, err := mc.SendAndRead(context.Background(), DefaultServers, pkt, nil); err != ErrNoResponse { + t.Errorf("SendAndRead(%v) = %v, want %v", pkt, err, ErrNoResponse) + } + + if _, err := mc.SendAndRead(context.Background(), DefaultServers, pkt, nil); err != ErrNoResponse { + t.Errorf("SendAndRead(%v) = %v, want %v", pkt, err, ErrNoResponse) + } +} + +func TestSimpleSendAndReadDiscardGarbage(t *testing.T) { + pkt := newPacket(dhcpv4.OpcodeBootRequest, [4]byte{0x33, 0x33, 0x33, 0x33}) + + responses := newPacket(dhcpv4.OpcodeBootReply, [4]byte{0x33, 0x33, 0x33, 0x33}) + + // Both the server and client only get 2 seconds. + ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second) + defer cancel() + + mc, udpConn := serveAndClient(ctx, [][]*dhcpv4.DHCPv4{{responses}}) + defer mc.Close() + + // Too short for valid DHCPv4 packet. + udpConn.WriteTo([]byte{0x01}, nil) + udpConn.WriteTo([]byte{0x01, 0x2}, nil) + + rcvd, err := mc.SendAndRead(ctx, DefaultServers, pkt, nil) + if err != nil { + t.Errorf("SendAndRead(%v) = %v, want nil", pkt, err) + } + + if err := ComparePacket(rcvd, responses); err != nil { + t.Errorf("got unexpected packets: %v", err) + } +} + +func TestMultipleSendAndRead(t *testing.T) { + for _, tt := range []struct { + desc string + send []*dhcpv4.DHCPv4 + server [][]*dhcpv4.DHCPv4 + wantErr []error + }{ + { + desc: "two requests, two responses", + send: []*dhcpv4.DHCPv4{ + newPacket(dhcpv4.OpcodeBootRequest, [4]byte{0x33, 0x33, 0x33, 0x33}), + newPacket(dhcpv4.OpcodeBootRequest, [4]byte{0x44, 0x44, 0x44, 0x44}), + }, + server: [][]*dhcpv4.DHCPv4{ + []*dhcpv4.DHCPv4{ // Response for first packet. + newPacket(dhcpv4.OpcodeBootReply, [4]byte{0x33, 0x33, 0x33, 0x33}), + }, + []*dhcpv4.DHCPv4{ // Response for second packet. + newPacket(dhcpv4.OpcodeBootReply, [4]byte{0x44, 0x44, 0x44, 0x44}), + }, + }, + wantErr: []error{ + nil, + nil, + }, + }, + } { + // Both server and client only get 2 seconds. + ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second) + defer cancel() + + mc, _ := serveAndClient(ctx, tt.server) + defer mc.Close() + + for i, send := range tt.send { + ctx, cancel = context.WithTimeout(context.Background(), 2*time.Second) + defer cancel() + rcvd, err := mc.SendAndRead(ctx, DefaultServers, send, nil) + + if wantErr := tt.wantErr[i]; err != wantErr { + t.Errorf("SendAndReadOne(%v): got %v, want %v", send, err, wantErr) + } + if err := pktsExpected([]*dhcpv4.DHCPv4{rcvd}, tt.server[i]); err != nil { + t.Errorf("got unexpected packets: %v", err) + } + } + } +} diff --git a/dhcpv4/nclient4/conn_linux.go b/dhcpv4/nclient4/conn_linux.go new file mode 100644 index 0000000..00c8a32 --- /dev/null +++ b/dhcpv4/nclient4/conn_linux.go @@ -0,0 +1,173 @@ +// Copyright 2018 the u-root Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// +build go1.12 + +package nclient4 + +import ( + "fmt" + "io" + "net" + "os" + + "github.com/insomniacslk/dhcp/dhcpv4" + "github.com/mdlayher/ethernet" + "github.com/mdlayher/raw" + "github.com/u-root/u-root/pkg/uio" + "golang.org/x/sys/unix" +) + +var ( + // BroadcastMac is the broadcast MAC address. + // + // Any UDP packet sent to this address is broadcast on the subnet. + BroadcastMac = net.HardwareAddr([]byte{255, 255, 255, 255, 255, 255}) +) + +// NewIPv4UDPConn returns a UDP connection bound to both the interface and port +// given based on a IPv4 DGRAM socket. The UDP connection allows broadcasting. +// +// The interface must already be configured. +func NewIPv4UDPConn(iface string, port int) (net.PacketConn, error) { + fd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, unix.IPPROTO_UDP) + if err != nil { + return nil, fmt.Errorf("cannot get a UDP socket: %v", err) + } + f := os.NewFile(uintptr(fd), "") + // net.FilePacketConn dups the FD, so we have to close this in any case. + defer f.Close() + + // Allow broadcasting. + if err := unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_BROADCAST, 1); err != nil { + return nil, fmt.Errorf("cannot set broadcasting on socket: %v", err) + } + // Allow reusing the addr to aid debugging. + if err := unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_REUSEADDR, 1); err != nil { + return nil, fmt.Errorf("cannot set reuseaddr on socket: %v", err) + } + if len(iface) != 0 { + // Bind directly to the interface. + if err := dhcpv4.BindToInterface(fd, iface); err != nil { + return nil, fmt.Errorf("cannot bind to interface %s: %v", iface, err) + } + } + // Bind to the port. + if err := unix.Bind(fd, &unix.SockaddrInet4{Port: port}); err != nil { + return nil, fmt.Errorf("cannot bind to port %d: %v", port, err) + } + + return net.FilePacketConn(f) +} + +// NewRawUDPConn returns a UDP connection bound to the interface and port +// given based on a raw packet socket. All packets are broadcasted. +// +// The interface can be completely unconfigured. +func NewRawUDPConn(iface string, port int) (net.PacketConn, error) { + ifc, err := net.InterfaceByName(iface) + if err != nil { + return nil, err + } + rawConn, err := raw.ListenPacket(ifc, uint16(ethernet.EtherTypeIPv4), &raw.Config{LinuxSockDGRAM: true}) + if err != nil { + return nil, err + } + return NewBroadcastUDPConn(rawConn, &net.UDPAddr{Port: port}), nil +} + +// BroadcastRawUDPConn uses a raw socket to send UDP packets to the broadcast +// MAC address. +type BroadcastRawUDPConn struct { + // PacketConn is a raw DGRAM socket. + net.PacketConn + + // boundAddr is the address this RawUDPConn is "bound" to. + // + // Calls to ReadFrom will only return packets destined to this address. + boundAddr *net.UDPAddr +} + +// NewBroadcastUDPConn returns a PacketConn that marshals and unmarshals UDP +// packets, sending them to the broadcast MAC at on rawPacketConn. +// +// Calls to ReadFrom will only return packets destined to boundAddr. +func NewBroadcastUDPConn(rawPacketConn net.PacketConn, boundAddr *net.UDPAddr) net.PacketConn { + return &BroadcastRawUDPConn{ + PacketConn: rawPacketConn, + boundAddr: boundAddr, + } +} + +func udpMatch(addr *net.UDPAddr, bound *net.UDPAddr) bool { + if bound == nil { + return true + } + if bound.IP != nil && !bound.IP.Equal(addr.IP) { + return false + } + return bound.Port == addr.Port +} + +// ReadFrom implements net.PacketConn.ReadFrom. +// +// ReadFrom reads raw IP packets and will try to match them against +// upc.boundAddr. Any matching packets are returned via the given buffer. +func (upc *BroadcastRawUDPConn) ReadFrom(b []byte) (int, net.Addr, error) { + ipLen := IPv4MaximumHeaderSize + udpLen := UDPMinimumSize + + for { + pkt := make([]byte, ipLen+udpLen+len(b)) + n, _, err := upc.PacketConn.ReadFrom(pkt) + if err != nil { + return 0, nil, err + } + if n == 0 { + return 0, nil, io.EOF + } + pkt = pkt[:n] + buf := uio.NewBigEndianBuffer(pkt) + + // To read the header length, access data directly. + ipHdr := IPv4(buf.Data()) + ipHdr = IPv4(buf.Consume(int(ipHdr.HeaderLength()))) + + if ipHdr.TransportProtocol() != UDPProtocolNumber { + continue + } + udpHdr := UDP(buf.Consume(udpLen)) + + addr := &net.UDPAddr{ + IP: net.IP(ipHdr.DestinationAddress()), + Port: int(udpHdr.DestinationPort()), + } + if !udpMatch(addr, upc.boundAddr) { + continue + } + srcAddr := &net.UDPAddr{ + IP: net.IP(ipHdr.SourceAddress()), + Port: int(udpHdr.SourcePort()), + } + return copy(b, buf.ReadAll()), srcAddr, nil + } +} + +// WriteTo implements net.PacketConn.WriteTo and broadcasts all packets at the +// raw socket level. +// +// WriteTo wraps the given packet in the appropriate UDP and IP header before +// sending it on the packet conn. +func (upc *BroadcastRawUDPConn) WriteTo(b []byte, addr net.Addr) (int, error) { + udpAddr, ok := addr.(*net.UDPAddr) + if !ok { + return 0, fmt.Errorf("must supply UDPAddr") + } + + // Using the boundAddr is not quite right here, but it works. + packet := udp4pkt(b, udpAddr, upc.boundAddr) + + // Broadcasting is not always right, but hell, what the ARP do I know. + return upc.PacketConn.WriteTo(packet, &raw.Addr{HardwareAddr: BroadcastMac}) +} diff --git a/dhcpv4/nclient4/ipv4.go b/dhcpv4/nclient4/ipv4.go new file mode 100644 index 0000000..81ba837 --- /dev/null +++ b/dhcpv4/nclient4/ipv4.go @@ -0,0 +1,376 @@ +// Copyright 2018 Google LLC +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. +// +// This file contains code taken from gVisor. + +// +build go1.12 + +package nclient4 + +import ( + "encoding/binary" + "net" + + "github.com/u-root/u-root/pkg/uio" +) + +const ( + versIHL = 0 + tos = 1 + totalLen = 2 + id = 4 + flagsFO = 6 + ttl = 8 + protocol = 9 + checksum = 10 + srcAddr = 12 + dstAddr = 16 +) + +// TransportProtocolNumber is the number of a transport protocol. +type TransportProtocolNumber uint32 + +// IPv4Fields contains the fields of an IPv4 packet. It is used to describe the +// fields of a packet that needs to be encoded. +type IPv4Fields struct { + // IHL is the "internet header length" field of an IPv4 packet. + IHL uint8 + + // TOS is the "type of service" field of an IPv4 packet. + TOS uint8 + + // TotalLength is the "total length" field of an IPv4 packet. + TotalLength uint16 + + // ID is the "identification" field of an IPv4 packet. + ID uint16 + + // Flags is the "flags" field of an IPv4 packet. + Flags uint8 + + // FragmentOffset is the "fragment offset" field of an IPv4 packet. + FragmentOffset uint16 + + // TTL is the "time to live" field of an IPv4 packet. + TTL uint8 + + // Protocol is the "protocol" field of an IPv4 packet. + Protocol uint8 + + // Checksum is the "checksum" field of an IPv4 packet. + Checksum uint16 + + // SrcAddr is the "source ip address" of an IPv4 packet. + SrcAddr net.IP + + // DstAddr is the "destination ip address" of an IPv4 packet. + DstAddr net.IP +} + +// IPv4 represents an ipv4 header stored in a byte array. +// Most of the methods of IPv4 access to the underlying slice without +// checking the boundaries and could panic because of 'index out of range'. +// Always call IsValid() to validate an instance of IPv4 before using other methods. +type IPv4 []byte + +const ( + // IPv4MinimumSize is the minimum size of a valid IPv4 packet. + IPv4MinimumSize = 20 + + // IPv4MaximumHeaderSize is the maximum size of an IPv4 header. Given + // that there are only 4 bits to represents the header length in 32-bit + // units, the header cannot exceed 15*4 = 60 bytes. + IPv4MaximumHeaderSize = 60 + + // IPv4AddressSize is the size, in bytes, of an IPv4 address. + IPv4AddressSize = 4 + + // IPv4Version is the version of the ipv4 protocol. + IPv4Version = 4 +) + +var ( + // IPv4Broadcast is the broadcast address of the IPv4 procotol. + IPv4Broadcast = net.IP{0xff, 0xff, 0xff, 0xff} + + // IPv4Any is the non-routable IPv4 "any" meta address. + IPv4Any = net.IP{0, 0, 0, 0} +) + +// Flags that may be set in an IPv4 packet. +const ( + IPv4FlagMoreFragments = 1 << iota + IPv4FlagDontFragment +) + +// HeaderLength returns the value of the "header length" field of the ipv4 +// header. +func (b IPv4) HeaderLength() uint8 { + return (b[versIHL] & 0xf) * 4 +} + +// Protocol returns the value of the protocol field of the ipv4 header. +func (b IPv4) Protocol() uint8 { + return b[protocol] +} + +// SourceAddress returns the "source address" field of the ipv4 header. +func (b IPv4) SourceAddress() net.IP { + return net.IP(b[srcAddr : srcAddr+IPv4AddressSize]) +} + +// DestinationAddress returns the "destination address" field of the ipv4 +// header. +func (b IPv4) DestinationAddress() net.IP { + return net.IP(b[dstAddr : dstAddr+IPv4AddressSize]) +} + +// TransportProtocol implements Network.TransportProtocol. +func (b IPv4) TransportProtocol() TransportProtocolNumber { + return TransportProtocolNumber(b.Protocol()) +} + +// Payload implements Network.Payload. +func (b IPv4) Payload() []byte { + return b[b.HeaderLength():][:b.PayloadLength()] +} + +// PayloadLength returns the length of the payload portion of the ipv4 packet. +func (b IPv4) PayloadLength() uint16 { + return b.TotalLength() - uint16(b.HeaderLength()) +} + +// TotalLength returns the "total length" field of the ipv4 header. +func (b IPv4) TotalLength() uint16 { + return binary.BigEndian.Uint16(b[totalLen:]) +} + +// SetTotalLength sets the "total length" field of the ipv4 header. +func (b IPv4) SetTotalLength(totalLength uint16) { + binary.BigEndian.PutUint16(b[totalLen:], totalLength) +} + +// SetChecksum sets the checksum field of the ipv4 header. +func (b IPv4) SetChecksum(v uint16) { + binary.BigEndian.PutUint16(b[checksum:], v) +} + +// SetFlagsFragmentOffset sets the "flags" and "fragment offset" fields of the +// ipv4 header. +func (b IPv4) SetFlagsFragmentOffset(flags uint8, offset uint16) { + v := (uint16(flags) << 13) | (offset >> 3) + binary.BigEndian.PutUint16(b[flagsFO:], v) +} + +// SetSourceAddress sets the "source address" field of the ipv4 header. +func (b IPv4) SetSourceAddress(addr net.IP) { + copy(b[srcAddr:srcAddr+IPv4AddressSize], addr.To4()) +} + +// SetDestinationAddress sets the "destination address" field of the ipv4 +// header. +func (b IPv4) SetDestinationAddress(addr net.IP) { + copy(b[dstAddr:dstAddr+IPv4AddressSize], addr.To4()) +} + +// CalculateChecksum calculates the checksum of the ipv4 header. +func (b IPv4) CalculateChecksum() uint16 { + return Checksum(b[:b.HeaderLength()], 0) +} + +// Encode encodes all the fields of the ipv4 header. +func (b IPv4) Encode(i *IPv4Fields) { + b[versIHL] = (4 << 4) | ((i.IHL / 4) & 0xf) + b[tos] = i.TOS + b.SetTotalLength(i.TotalLength) + binary.BigEndian.PutUint16(b[id:], i.ID) + b.SetFlagsFragmentOffset(i.Flags, i.FragmentOffset) + b[ttl] = i.TTL + b[protocol] = i.Protocol + b.SetChecksum(i.Checksum) + copy(b[srcAddr:srcAddr+IPv4AddressSize], i.SrcAddr) + copy(b[dstAddr:dstAddr+IPv4AddressSize], i.DstAddr) +} + +const ( + udpSrcPort = 0 + udpDstPort = 2 + udpLength = 4 + udpChecksum = 6 +) + +// UDPFields contains the fields of a UDP packet. It is used to describe the +// fields of a packet that needs to be encoded. +type UDPFields struct { + // SrcPort is the "source port" field of a UDP packet. + SrcPort uint16 + + // DstPort is the "destination port" field of a UDP packet. + DstPort uint16 + + // Length is the "length" field of a UDP packet. + Length uint16 + + // Checksum is the "checksum" field of a UDP packet. + Checksum uint16 +} + +// UDP represents a UDP header stored in a byte array. +type UDP []byte + +const ( + // UDPMinimumSize is the minimum size of a valid UDP packet. + UDPMinimumSize = 8 + + // UDPProtocolNumber is UDP's transport protocol number. + UDPProtocolNumber TransportProtocolNumber = 17 +) + +// SourcePort returns the "source port" field of the udp header. +func (b UDP) SourcePort() uint16 { + return binary.BigEndian.Uint16(b[udpSrcPort:]) +} + +// DestinationPort returns the "destination port" field of the udp header. +func (b UDP) DestinationPort() uint16 { + return binary.BigEndian.Uint16(b[udpDstPort:]) +} + +// Length returns the "length" field of the udp header. +func (b UDP) Length() uint16 { + return binary.BigEndian.Uint16(b[udpLength:]) +} + +// SetSourcePort sets the "source port" field of the udp header. +func (b UDP) SetSourcePort(port uint16) { + binary.BigEndian.PutUint16(b[udpSrcPort:], port) +} + +// SetDestinationPort sets the "destination port" field of the udp header. +func (b UDP) SetDestinationPort(port uint16) { + binary.BigEndian.PutUint16(b[udpDstPort:], port) +} + +// SetChecksum sets the "checksum" field of the udp header. +func (b UDP) SetChecksum(checksum uint16) { + binary.BigEndian.PutUint16(b[udpChecksum:], checksum) +} + +// Payload returns the data contained in the UDP datagram. +func (b UDP) Payload() []byte { + return b[UDPMinimumSize:] +} + +// Checksum returns the "checksum" field of the udp header. +func (b UDP) Checksum() uint16 { + return binary.BigEndian.Uint16(b[udpChecksum:]) +} + +// CalculateChecksum calculates the checksum of the udp packet, given the total +// length of the packet and the checksum of the network-layer pseudo-header +// (excluding the total length) and the checksum of the payload. +func (b UDP) CalculateChecksum(partialChecksum uint16, totalLen uint16) uint16 { + // Add the length portion of the checksum to the pseudo-checksum. + tmp := make([]byte, 2) + binary.BigEndian.PutUint16(tmp, totalLen) + checksum := Checksum(tmp, partialChecksum) + + // Calculate the rest of the checksum. + return Checksum(b[:UDPMinimumSize], checksum) +} + +// Encode encodes all the fields of the udp header. +func (b UDP) Encode(u *UDPFields) { + binary.BigEndian.PutUint16(b[udpSrcPort:], u.SrcPort) + binary.BigEndian.PutUint16(b[udpDstPort:], u.DstPort) + binary.BigEndian.PutUint16(b[udpLength:], u.Length) + binary.BigEndian.PutUint16(b[udpChecksum:], u.Checksum) +} + +func calculateChecksum(buf []byte, initial uint32) uint16 { + v := initial + + l := len(buf) + if l&1 != 0 { + l-- + v += uint32(buf[l]) << 8 + } + + for i := 0; i < l; i += 2 { + v += (uint32(buf[i]) << 8) + uint32(buf[i+1]) + } + + return ChecksumCombine(uint16(v), uint16(v>>16)) +} + +// Checksum calculates the checksum (as defined in RFC 1071) of the bytes in the +// given byte array. +// +// The initial checksum must have been computed on an even number of bytes. +func Checksum(buf []byte, initial uint16) uint16 { + return calculateChecksum(buf, uint32(initial)) +} + +// ChecksumCombine combines the two uint16 to form their checksum. This is done +// by adding them and the carry. +// +// Note that checksum a must have been computed on an even number of bytes. +func ChecksumCombine(a, b uint16) uint16 { + v := uint32(a) + uint32(b) + return uint16(v + v>>16) +} + +// PseudoHeaderChecksum calculates the pseudo-header checksum for the +// given destination protocol and network address, ignoring the length +// field. Pseudo-headers are needed by transport layers when calculating +// their own checksum. +func PseudoHeaderChecksum(protocol TransportProtocolNumber, srcAddr net.IP, dstAddr net.IP) uint16 { + xsum := Checksum([]byte(srcAddr), 0) + xsum = Checksum([]byte(dstAddr), xsum) + return Checksum([]byte{0, uint8(protocol)}, xsum) +} + +func udp4pkt(packet []byte, dest *net.UDPAddr, src *net.UDPAddr) []byte { + ipLen := IPv4MinimumSize + udpLen := UDPMinimumSize + + h := make([]byte, 0, ipLen+udpLen+len(packet)) + hdr := uio.NewBigEndianBuffer(h) + + ipv4fields := &IPv4Fields{ + IHL: IPv4MinimumSize, + TotalLength: uint16(ipLen + udpLen + len(packet)), + TTL: 30, + Protocol: uint8(UDPProtocolNumber), + SrcAddr: src.IP.To4(), + DstAddr: dest.IP.To4(), + } + ipv4hdr := IPv4(hdr.WriteN(ipLen)) + ipv4hdr.Encode(ipv4fields) + ipv4hdr.SetChecksum(^ipv4hdr.CalculateChecksum()) + + udphdr := UDP(hdr.WriteN(udpLen)) + udphdr.Encode(&UDPFields{ + SrcPort: uint16(src.Port), + DstPort: uint16(dest.Port), + Length: uint16(udpLen + len(packet)), + }) + + xsum := Checksum(packet, PseudoHeaderChecksum( + ipv4hdr.TransportProtocol(), ipv4fields.SrcAddr, ipv4fields.DstAddr)) + udphdr.SetChecksum(^udphdr.CalculateChecksum(xsum, udphdr.Length())) + + hdr.WriteBytes(packet) + return hdr.Data() +} diff --git a/dhcpv4/server4/server.go b/dhcpv4/server4/server.go index 5ef4479..1ccd5f4 100644 --- a/dhcpv4/server4/server.go +++ b/dhcpv4/server4/server.go @@ -1,11 +1,9 @@ package server4 import ( - "fmt" "log" "net" "sync" - "time" "github.com/insomniacslk/dhcp/dhcpv4" ) @@ -36,7 +34,7 @@ import ( "github.com/insomniacslk/dhcp/dhcpv4" ) -func handler(conn net.PacketConn, peer net.Addr, m dhcpv4.DHCPv4) { +func handler(conn net.PacketConn, peer net.Addr, m *dhcpv4.DHCPv4) { // this function will just print the received DHCPv4 message, without replying log.Print(m.Summary()) } @@ -46,12 +44,14 @@ func main() { IP: net.ParseIP("127.0.0.1"), Port: 67, } - server := dhcpv4.NewServer(laddr, handler) - - defer server.Close() - if err := server.ActivateAndServe(); err != nil { - log.Panic(err) + server, err := dhcpv4.NewServer(laddr, handler) + if err != nil { + log.Fatal(err) } + + // This never returns. If you want to do other stuff, dump it into a + // goroutine. + server.Serve() } */ @@ -66,98 +66,61 @@ type Server struct { connMutex sync.Mutex shouldStop chan bool Handler Handler - localAddr net.UDPAddr -} - -// LocalAddr returns the local address of the listening socket, or nil if not -// listening -func (s *Server) LocalAddr() net.Addr { - s.connMutex.Lock() - defer s.connMutex.Unlock() - if s.conn == nil { - return nil - } - return s.conn.LocalAddr() } -// ActivateAndServe starts the DHCPv4 server. The listener will run in -// background, and can be interrupted with `Server.Close`. -func (s *Server) ActivateAndServe() error { - s.connMutex.Lock() - if s.conn != nil { - // this may panic if s.conn is closed but not reset properly. For that - // you should use `Server.Close`. - s.Close() - } - conn, err := net.ListenUDP("udp4", &s.localAddr) - if err != nil { - s.connMutex.Unlock() - return err - } - s.conn = conn - s.connMutex.Unlock() - var ( - pc *net.UDPConn - ok bool - ) - if pc, ok = s.conn.(*net.UDPConn); !ok { - return fmt.Errorf("error: not an UDPConn") - } - if pc == nil { - return fmt.Errorf("ActivateAndServe: invalid nil PacketConn") - } - log.Printf("Server listening on %s", pc.LocalAddr()) +// Serve serves requests. +func (s *Server) Serve() { + log.Printf("Server listening on %s", s.conn.LocalAddr()) log.Print("Ready to handle requests") for { - select { - case <-s.shouldStop: - break - case <-time.After(time.Millisecond): - } - pc.SetReadDeadline(time.Now().Add(time.Second)) rbuf := make([]byte, 4096) // FIXME this is bad - n, peer, err := pc.ReadFrom(rbuf) + n, peer, err := s.conn.ReadFrom(rbuf) if err != nil { - switch err.(type) { - case net.Error: - if !err.(net.Error).Timeout() { - return err - } - // if timeout, silently skip and continue - default: - // complain and continue - log.Printf("Error reading from packet conn: %v", err) - } - continue + log.Printf("Error reading from packet conn: %v", err) + return } log.Printf("Handling request from %v", peer) + m, err := dhcpv4.FromBytes(rbuf[:n]) if err != nil { log.Printf("Error parsing DHCPv4 request: %v", err) continue } - go s.Handler(pc, peer, m) + go s.Handler(s.conn, peer, m) } } // Close sends a termination request to the server, and closes the UDP listener func (s *Server) Close() error { - s.shouldStop <- true - s.connMutex.Lock() - defer s.connMutex.Unlock() - if s.conn != nil { - ret := s.conn.Close() - s.conn = nil - return ret + return s.conn.Close() +} + +// ServerOpt adds optional configuration to a server. +type ServerOpt func(s *Server) + +// WithConn configures the server with the given connection. +func WithConn(c net.PacketConn) ServerOpt { + return func(s *Server) { + s.conn = c } - return nil } // NewServer initializes and returns a new Server object -func NewServer(addr net.UDPAddr, handler Handler) *Server { - return &Server{ - localAddr: addr, +func NewServer(addr *net.UDPAddr, handler Handler, opt ...ServerOpt) (*Server, error) { + s := &Server{ Handler: handler, shouldStop: make(chan bool, 1), } + + for _, o := range opt { + o(s) + } + if s.conn == nil { + var err error + s.conn, err = net.ListenUDP("udp4", addr) + if err != nil { + return nil, err + } + } + return s, nil } diff --git a/dhcpv4/server4/server_test.go b/dhcpv4/server4/server_test.go index f6ce18e..a6895d2 100644 --- a/dhcpv4/server4/server_test.go +++ b/dhcpv4/server4/server_test.go @@ -1,8 +1,9 @@ -// +build integration +// +build go1.12 package server4 import ( + "context" "log" "math/rand" "net" @@ -10,7 +11,7 @@ import ( "time" "github.com/insomniacslk/dhcp/dhcpv4" - "github.com/insomniacslk/dhcp/dhcpv4/client4" + "github.com/insomniacslk/dhcp/dhcpv4/nclient4" "github.com/insomniacslk/dhcp/interfaces" "github.com/stretchr/testify/require" ) @@ -61,68 +62,58 @@ func DORAHandler(conn net.PacketConn, peer net.Addr, m *dhcpv4.DHCPv4) { // utility function to set up a client and a server instance and run it in // background. The caller needs to call Server.Close() once finished. -func setUpClientAndServer(handler Handler) (*client4.Client, *Server) { +func setUpClientAndServer(t *testing.T, iface net.Interface, handler Handler) (*nclient4.Client, *Server) { // strong assumption, I know loAddr := net.ParseIP("127.0.0.1") - laddr := net.UDPAddr{ + saddr := net.UDPAddr{ IP: loAddr, Port: randPort(), } - s := NewServer(laddr, handler) - go s.ActivateAndServe() - - c := client4.NewClient() - // FIXME this doesn't deal well with raw sockets, the actual 0 will be used - // in the UDP header as source port - c.LocalAddr = &net.UDPAddr{IP: loAddr, Port: randPort()} - for { - if s.LocalAddr() != nil { - break - } - time.Sleep(10 * time.Millisecond) - log.Printf("Waiting for server to run...") + caddr := net.UDPAddr{ + IP: loAddr, + Port: randPort(), } - c.RemoteAddr = s.LocalAddr() - log.Printf("Client.RemoteAddr: %s", c.RemoteAddr) - - return c, s -} - -func TestNewServer(t *testing.T) { - laddr := net.UDPAddr{ - IP: net.ParseIP("127.0.0.1"), - Port: 0, + s, err := NewServer(&saddr, handler) + if err != nil { + t.Fatal(err) } - s := NewServer(laddr, DORAHandler) - defer s.Close() + go s.Serve() - require.NotNil(t, s) - require.Nil(t, s.conn) - require.Equal(t, laddr, s.localAddr) - require.NotNil(t, s.Handler) + clientConn, err := nclient4.NewIPv4UDPConn("", caddr.Port) + if err != nil { + t.Fatal(err) + } + c := nclient4.NewWithConn(clientConn, iface.HardwareAddr, nclient4.WithServerAddr(&saddr)) + return c, s } -func TestServerActivateAndServe(t *testing.T) { - c, s := setUpClientAndServer(DORAHandler) - defer s.Close() - +func TestServer(t *testing.T) { ifaces, err := interfaces.GetLoopbackInterfaces() require.NoError(t, err) require.NotEqual(t, 0, len(ifaces)) + // lo has a HardwareAddr of "nil". The client will drop all packets + // that don't match the HWAddr of the client interface. + hwaddr := net.HardwareAddr{1, 2, 3, 4, 5, 6} + ifaces[0].HardwareAddr = hwaddr + + c, s := setUpClientAndServer(t, ifaces[0], DORAHandler) + defer func() { + require.Nil(t, s.Close()) + }() + xid := dhcpv4.TransactionID{0xaa, 0xbb, 0xcc, 0xdd} - hwaddr := net.HardwareAddr{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf} modifiers := []dhcpv4.Modifier{ dhcpv4.WithTransactionID(xid), - dhcpv4.WithHwAddr(hwaddr), + dhcpv4.WithHwAddr(ifaces[0].HardwareAddr), } - conv, err := c.Exchange(ifaces[0].Name, modifiers...) + offer, ack, err := c.Request(context.Background(), modifiers...) require.NoError(t, err) - require.Equal(t, 4, len(conv)) - for _, p := range conv { + require.NotNil(t, offer, ack) + for _, p := range []*dhcpv4.DHCPv4{offer, ack} { require.Equal(t, xid, p.TransactionID) - require.Equal(t, hwaddr, p.ClientHWAddr) + require.Equal(t, ifaces[0].HardwareAddr, p.ClientHWAddr) } } |