From d02b74a5dcfed4bfc8f2f8e545bca4d2afabb296 Mon Sep 17 00:00:00 2001 From: Googler Date: Fri, 27 Apr 2018 10:37:02 -0700 Subject: Check in gVisor. PiperOrigin-RevId: 194583126 Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463 --- pkg/tcpip/transport/udp/endpoint.go | 746 ++++++++++++++++++++++++++++++++++++ 1 file changed, 746 insertions(+) create mode 100644 pkg/tcpip/transport/udp/endpoint.go (limited to 'pkg/tcpip/transport/udp/endpoint.go') diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go new file mode 100644 index 000000000..80fa88c4c --- /dev/null +++ b/pkg/tcpip/transport/udp/endpoint.go @@ -0,0 +1,746 @@ +// Copyright 2016 The Netstack Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package udp + +import ( + "sync" + + "gvisor.googlesource.com/gvisor/pkg/sleep" + "gvisor.googlesource.com/gvisor/pkg/tcpip" + "gvisor.googlesource.com/gvisor/pkg/tcpip/buffer" + "gvisor.googlesource.com/gvisor/pkg/tcpip/header" + "gvisor.googlesource.com/gvisor/pkg/tcpip/stack" + "gvisor.googlesource.com/gvisor/pkg/waiter" +) + +type udpPacket struct { + udpPacketEntry + senderAddress tcpip.FullAddress + data buffer.VectorisedView `state:".(buffer.VectorisedView)"` + // views is used as buffer for data when its length is large + // enough to store a VectorisedView. + views [8]buffer.View `state:"nosave"` +} + +type endpointState int + +const ( + stateInitial endpointState = iota + stateBound + stateConnected + stateClosed +) + +// endpoint represents a UDP endpoint. This struct serves as the interface +// between users of the endpoint and the protocol implementation; it is legal to +// have concurrent goroutines make calls into the endpoint, they are properly +// synchronized. +type endpoint struct { + // The following fields are initialized at creation time and do not + // change throughout the lifetime of the endpoint. + stack *stack.Stack `state:"manual"` + netProto tcpip.NetworkProtocolNumber + waiterQueue *waiter.Queue + + // The following fields are used to manage the receive queue, and are + // protected by rcvMu. + rcvMu sync.Mutex `state:"nosave"` + rcvReady bool + rcvList udpPacketList + rcvBufSizeMax int `state:".(int)"` + rcvBufSize int + rcvClosed bool + + // The following fields are protected by the mu mutex. + mu sync.RWMutex `state:"nosave"` + sndBufSize int + id stack.TransportEndpointID + state endpointState + bindNICID tcpip.NICID + bindAddr tcpip.Address + regNICID tcpip.NICID + route stack.Route `state:"manual"` + dstPort uint16 + v6only bool + + // effectiveNetProtos contains the network protocols actually in use. In + // most cases it will only contain "netProto", but in cases like IPv6 + // endpoints with v6only set to false, this could include multiple + // protocols (e.g., IPv6 and IPv4) or a single different protocol (e.g., + // IPv4 when IPv6 endpoint is bound or connected to an IPv4 mapped + // address). + effectiveNetProtos []tcpip.NetworkProtocolNumber +} + +func newEndpoint(stack *stack.Stack, netProto tcpip.NetworkProtocolNumber, waiterQueue *waiter.Queue) *endpoint { + return &endpoint{ + stack: stack, + netProto: netProto, + waiterQueue: waiterQueue, + rcvBufSizeMax: 32 * 1024, + sndBufSize: 32 * 1024, + } +} + +// NewConnectedEndpoint creates a new endpoint in the connected state using the +// provided route. +func NewConnectedEndpoint(stack *stack.Stack, r *stack.Route, id stack.TransportEndpointID, waiterQueue *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) { + ep := newEndpoint(stack, r.NetProto, waiterQueue) + + // Register new endpoint so that packets are routed to it. + if err := stack.RegisterTransportEndpoint(r.NICID(), []tcpip.NetworkProtocolNumber{r.NetProto}, ProtocolNumber, id, ep); err != nil { + ep.Close() + return nil, err + } + + ep.id = id + ep.route = r.Clone() + ep.dstPort = id.RemotePort + ep.regNICID = r.NICID() + + ep.state = stateConnected + + return ep, nil +} + +// Close puts the endpoint in a closed state and frees all resources +// associated with it. +func (e *endpoint) Close() { + e.mu.Lock() + defer e.mu.Unlock() + + switch e.state { + case stateBound, stateConnected: + e.stack.UnregisterTransportEndpoint(e.regNICID, e.effectiveNetProtos, ProtocolNumber, e.id) + } + + // Close the receive list and drain it. + e.rcvMu.Lock() + e.rcvClosed = true + e.rcvBufSize = 0 + for !e.rcvList.Empty() { + p := e.rcvList.Front() + e.rcvList.Remove(p) + } + e.rcvMu.Unlock() + + e.route.Release() + + // Update the state. + e.state = stateClosed +} + +// Read reads data from the endpoint. This method does not block if +// there is no data pending. +func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, *tcpip.Error) { + e.rcvMu.Lock() + + if e.rcvList.Empty() { + err := tcpip.ErrWouldBlock + if e.rcvClosed { + err = tcpip.ErrClosedForReceive + } + e.rcvMu.Unlock() + return buffer.View{}, err + } + + p := e.rcvList.Front() + e.rcvList.Remove(p) + e.rcvBufSize -= p.data.Size() + + e.rcvMu.Unlock() + + if addr != nil { + *addr = p.senderAddress + } + + return p.data.ToView(), nil +} + +// prepareForWrite prepares the endpoint for sending data. In particular, it +// binds it if it's still in the initial state. To do so, it must first +// reacquire the mutex in exclusive mode. +// +// Returns true for retry if preparation should be retried. +func (e *endpoint) prepareForWrite(to *tcpip.FullAddress) (retry bool, err *tcpip.Error) { + switch e.state { + case stateInitial: + case stateConnected: + return false, nil + + case stateBound: + if to == nil { + return false, tcpip.ErrDestinationRequired + } + return false, nil + default: + return false, tcpip.ErrInvalidEndpointState + } + + e.mu.RUnlock() + defer e.mu.RLock() + + e.mu.Lock() + defer e.mu.Unlock() + + // The state changed when we released the shared locked and re-acquired + // it in exclusive mode. Try again. + if e.state != stateInitial { + return true, nil + } + + // The state is still 'initial', so try to bind the endpoint. + if err := e.bindLocked(tcpip.FullAddress{}, nil); err != nil { + return false, err + } + + return true, nil +} + +// Write writes data to the endpoint's peer. This method does not block +// if the data cannot be written. +func (e *endpoint) Write(p tcpip.Payload, opts tcpip.WriteOptions) (uintptr, *tcpip.Error) { + // MSG_MORE is unimplemented. (This also means that MSG_EOR is a no-op.) + if opts.More { + return 0, tcpip.ErrInvalidOptionValue + } + + to := opts.To + + e.mu.RLock() + defer e.mu.RUnlock() + + // Prepare for write. + for { + retry, err := e.prepareForWrite(to) + if err != nil { + return 0, err + } + + if !retry { + break + } + } + + var route *stack.Route + var dstPort uint16 + if to == nil { + route = &e.route + dstPort = e.dstPort + + if route.IsResolutionRequired() { + // Promote lock to exclusive if using a shared route, given that it may need to + // change in Route.Resolve() call below. + e.mu.RUnlock() + defer e.mu.RLock() + + e.mu.Lock() + defer e.mu.Unlock() + + // Recheck state after lock was re-acquired. + if e.state != stateConnected { + return 0, tcpip.ErrInvalidEndpointState + } + } + } else { + // Reject destination address if it goes through a different + // NIC than the endpoint was bound to. + nicid := to.NIC + if e.bindNICID != 0 { + if nicid != 0 && nicid != e.bindNICID { + return 0, tcpip.ErrNoRoute + } + + nicid = e.bindNICID + } + + toCopy := *to + to = &toCopy + netProto, err := e.checkV4Mapped(to, true) + if err != nil { + return 0, err + } + + // Find the enpoint. + r, err := e.stack.FindRoute(nicid, e.bindAddr, to.Addr, netProto) + if err != nil { + return 0, err + } + defer r.Release() + + route = &r + dstPort = to.Port + } + + if route.IsResolutionRequired() { + waker := &sleep.Waker{} + if err := route.Resolve(waker); err != nil { + if err == tcpip.ErrWouldBlock { + // Link address needs to be resolved. Resolution was triggered the background. + // Better luck next time. + // + // TODO: queue up the request and send after link address + // is resolved. + route.RemoveWaker(waker) + return 0, tcpip.ErrNoLinkAddress + } + return 0, err + } + } + + v, err := p.Get(p.Size()) + if err != nil { + return 0, err + } + sendUDP(route, v, e.id.LocalPort, dstPort) + return uintptr(len(v)), nil +} + +// Peek only returns data from a single datagram, so do nothing here. +func (e *endpoint) Peek([][]byte) (uintptr, *tcpip.Error) { + return 0, nil +} + +// SetSockOpt sets a socket option. Currently not supported. +func (e *endpoint) SetSockOpt(opt interface{}) *tcpip.Error { + // TODO: Actually implement this. + switch v := opt.(type) { + case tcpip.V6OnlyOption: + // We only recognize this option on v6 endpoints. + if e.netProto != header.IPv6ProtocolNumber { + return tcpip.ErrInvalidEndpointState + } + + e.mu.Lock() + defer e.mu.Unlock() + + // We only allow this to be set when we're in the initial state. + if e.state != stateInitial { + return tcpip.ErrInvalidEndpointState + } + + e.v6only = v != 0 + } + return nil +} + +// GetSockOpt implements tcpip.Endpoint.GetSockOpt. +func (e *endpoint) GetSockOpt(opt interface{}) *tcpip.Error { + switch o := opt.(type) { + case tcpip.ErrorOption: + return nil + + case *tcpip.SendBufferSizeOption: + e.mu.Lock() + *o = tcpip.SendBufferSizeOption(e.sndBufSize) + e.mu.Unlock() + return nil + + case *tcpip.ReceiveBufferSizeOption: + e.rcvMu.Lock() + *o = tcpip.ReceiveBufferSizeOption(e.rcvBufSizeMax) + e.rcvMu.Unlock() + return nil + + case *tcpip.V6OnlyOption: + // We only recognize this option on v6 endpoints. + if e.netProto != header.IPv6ProtocolNumber { + return tcpip.ErrUnknownProtocolOption + } + + e.mu.Lock() + v := e.v6only + e.mu.Unlock() + + *o = 0 + if v { + *o = 1 + } + return nil + + case *tcpip.ReceiveQueueSizeOption: + e.rcvMu.Lock() + if e.rcvList.Empty() { + *o = 0 + } else { + p := e.rcvList.Front() + *o = tcpip.ReceiveQueueSizeOption(p.data.Size()) + } + e.rcvMu.Unlock() + return nil + } + + return tcpip.ErrUnknownProtocolOption +} + +// sendUDP sends a UDP segment via the provided network endpoint and under the +// provided identity. +func sendUDP(r *stack.Route, data buffer.View, localPort, remotePort uint16) *tcpip.Error { + // Allocate a buffer for the UDP header. + hdr := buffer.NewPrependable(header.UDPMinimumSize + int(r.MaxHeaderLength())) + + // Initialize the header. + udp := header.UDP(hdr.Prepend(header.UDPMinimumSize)) + + length := uint16(hdr.UsedLength()) + uint16(len(data)) + udp.Encode(&header.UDPFields{ + SrcPort: localPort, + DstPort: remotePort, + Length: length, + }) + + // Only calculate the checksum if offloading isn't supported. + if r.Capabilities()&stack.CapabilityChecksumOffload == 0 { + xsum := r.PseudoHeaderChecksum(ProtocolNumber) + if data != nil { + xsum = header.Checksum(data, xsum) + } + + udp.SetChecksum(^udp.CalculateChecksum(xsum, length)) + } + + return r.WritePacket(&hdr, data, ProtocolNumber) +} + +func (e *endpoint) checkV4Mapped(addr *tcpip.FullAddress, allowMismatch bool) (tcpip.NetworkProtocolNumber, *tcpip.Error) { + netProto := e.netProto + if header.IsV4MappedAddress(addr.Addr) { + // Fail if using a v4 mapped address on a v6only endpoint. + if e.v6only { + return 0, tcpip.ErrNoRoute + } + + netProto = header.IPv4ProtocolNumber + addr.Addr = addr.Addr[header.IPv6AddressSize-header.IPv4AddressSize:] + if addr.Addr == "\x00\x00\x00\x00" { + addr.Addr = "" + } + } + + // Fail if we're bound to an address length different from the one we're + // checking. + if l := len(e.id.LocalAddress); !allowMismatch && l != 0 && l != len(addr.Addr) { + return 0, tcpip.ErrInvalidEndpointState + } + + return netProto, nil +} + +// Connect connects the endpoint to its peer. Specifying a NIC is optional. +func (e *endpoint) Connect(addr tcpip.FullAddress) *tcpip.Error { + if addr.Port == 0 { + // We don't support connecting to port zero. + return tcpip.ErrInvalidEndpointState + } + + e.mu.Lock() + defer e.mu.Unlock() + + nicid := addr.NIC + localPort := uint16(0) + switch e.state { + case stateInitial: + case stateBound, stateConnected: + localPort = e.id.LocalPort + if e.bindNICID == 0 { + break + } + + if nicid != 0 && nicid != e.bindNICID { + return tcpip.ErrInvalidEndpointState + } + + nicid = e.bindNICID + default: + return tcpip.ErrInvalidEndpointState + } + + netProto, err := e.checkV4Mapped(&addr, false) + if err != nil { + return err + } + + // Find a route to the desired destination. + r, err := e.stack.FindRoute(nicid, e.bindAddr, addr.Addr, netProto) + if err != nil { + return err + } + defer r.Release() + + id := stack.TransportEndpointID{ + LocalAddress: r.LocalAddress, + LocalPort: localPort, + RemotePort: addr.Port, + RemoteAddress: r.RemoteAddress, + } + + // Even if we're connected, this endpoint can still be used to send + // packets on a different network protocol, so we register both even if + // v6only is set to false and this is an ipv6 endpoint. + netProtos := []tcpip.NetworkProtocolNumber{netProto} + if e.netProto == header.IPv6ProtocolNumber && !e.v6only { + netProtos = []tcpip.NetworkProtocolNumber{ + header.IPv4ProtocolNumber, + header.IPv6ProtocolNumber, + } + } + + id, err = e.registerWithStack(nicid, netProtos, id) + if err != nil { + return err + } + + // Remove the old registration. + if e.id.LocalPort != 0 { + e.stack.UnregisterTransportEndpoint(e.regNICID, e.effectiveNetProtos, ProtocolNumber, e.id) + } + + e.id = id + e.route = r.Clone() + e.dstPort = addr.Port + e.regNICID = nicid + e.effectiveNetProtos = netProtos + + e.state = stateConnected + + e.rcvMu.Lock() + e.rcvReady = true + e.rcvMu.Unlock() + + return nil +} + +// ConnectEndpoint is not supported. +func (*endpoint) ConnectEndpoint(tcpip.Endpoint) *tcpip.Error { + return tcpip.ErrInvalidEndpointState +} + +// Shutdown closes the read and/or write end of the endpoint connection +// to its peer. +func (e *endpoint) Shutdown(flags tcpip.ShutdownFlags) *tcpip.Error { + e.mu.RLock() + defer e.mu.RUnlock() + + if e.state != stateConnected { + return tcpip.ErrNotConnected + } + + if flags&tcpip.ShutdownRead != 0 { + e.rcvMu.Lock() + wasClosed := e.rcvClosed + e.rcvClosed = true + e.rcvMu.Unlock() + + if !wasClosed { + e.waiterQueue.Notify(waiter.EventIn) + } + } + + return nil +} + +// Listen is not supported by UDP, it just fails. +func (*endpoint) Listen(int) *tcpip.Error { + return tcpip.ErrNotSupported +} + +// Accept is not supported by UDP, it just fails. +func (*endpoint) Accept() (tcpip.Endpoint, *waiter.Queue, *tcpip.Error) { + return nil, nil, tcpip.ErrNotSupported +} + +func (e *endpoint) registerWithStack(nicid tcpip.NICID, netProtos []tcpip.NetworkProtocolNumber, id stack.TransportEndpointID) (stack.TransportEndpointID, *tcpip.Error) { + if id.LocalPort != 0 { + // The endpoint already has a local port, just attempt to + // register it. + err := e.stack.RegisterTransportEndpoint(nicid, netProtos, ProtocolNumber, id, e) + return id, err + } + + // We need to find a port for the endpoint. + _, err := e.stack.PickEphemeralPort(func(p uint16) (bool, *tcpip.Error) { + id.LocalPort = p + err := e.stack.RegisterTransportEndpoint(nicid, netProtos, ProtocolNumber, id, e) + switch err { + case nil: + return true, nil + case tcpip.ErrPortInUse: + return false, nil + default: + return false, err + } + }) + + return id, err +} + +func (e *endpoint) bindLocked(addr tcpip.FullAddress, commit func() *tcpip.Error) *tcpip.Error { + // Don't allow binding once endpoint is not in the initial state + // anymore. + if e.state != stateInitial { + return tcpip.ErrInvalidEndpointState + } + + netProto, err := e.checkV4Mapped(&addr, false) + if err != nil { + return err + } + + // Expand netProtos to include v4 and v6 if the caller is binding to a + // wildcard (empty) address, and this is an IPv6 endpoint with v6only + // set to false. + netProtos := []tcpip.NetworkProtocolNumber{netProto} + if netProto == header.IPv6ProtocolNumber && !e.v6only && addr.Addr == "" { + netProtos = []tcpip.NetworkProtocolNumber{ + header.IPv6ProtocolNumber, + header.IPv4ProtocolNumber, + } + } + + if len(addr.Addr) != 0 { + // A local address was specified, verify that it's valid. + if e.stack.CheckLocalAddress(addr.NIC, netProto, addr.Addr) == 0 { + return tcpip.ErrBadLocalAddress + } + } + + id := stack.TransportEndpointID{ + LocalPort: addr.Port, + LocalAddress: addr.Addr, + } + id, err = e.registerWithStack(addr.NIC, netProtos, id) + if err != nil { + return err + } + if commit != nil { + if err := commit(); err != nil { + // Unregister, the commit failed. + e.stack.UnregisterTransportEndpoint(addr.NIC, netProtos, ProtocolNumber, id) + return err + } + } + + e.id = id + e.regNICID = addr.NIC + e.effectiveNetProtos = netProtos + + // Mark endpoint as bound. + e.state = stateBound + + e.rcvMu.Lock() + e.rcvReady = true + e.rcvMu.Unlock() + + return nil +} + +// Bind binds the endpoint to a specific local address and port. +// Specifying a NIC is optional. +func (e *endpoint) Bind(addr tcpip.FullAddress, commit func() *tcpip.Error) *tcpip.Error { + e.mu.Lock() + defer e.mu.Unlock() + + err := e.bindLocked(addr, commit) + if err != nil { + return err + } + + e.bindNICID = addr.NIC + e.bindAddr = addr.Addr + + return nil +} + +// GetLocalAddress returns the address to which the endpoint is bound. +func (e *endpoint) GetLocalAddress() (tcpip.FullAddress, *tcpip.Error) { + e.mu.RLock() + defer e.mu.RUnlock() + + return tcpip.FullAddress{ + NIC: e.regNICID, + Addr: e.id.LocalAddress, + Port: e.id.LocalPort, + }, nil +} + +// GetRemoteAddress returns the address to which the endpoint is connected. +func (e *endpoint) GetRemoteAddress() (tcpip.FullAddress, *tcpip.Error) { + e.mu.RLock() + defer e.mu.RUnlock() + + if e.state != stateConnected { + return tcpip.FullAddress{}, tcpip.ErrNotConnected + } + + return tcpip.FullAddress{ + NIC: e.regNICID, + Addr: e.id.RemoteAddress, + Port: e.id.RemotePort, + }, nil +} + +// Readiness returns the current readiness of the endpoint. For example, if +// waiter.EventIn is set, the endpoint is immediately readable. +func (e *endpoint) Readiness(mask waiter.EventMask) waiter.EventMask { + // The endpoint is always writable. + result := waiter.EventOut & mask + + // Determine if the endpoint is readable if requested. + if (mask & waiter.EventIn) != 0 { + e.rcvMu.Lock() + if !e.rcvList.Empty() || e.rcvClosed { + result |= waiter.EventIn + } + e.rcvMu.Unlock() + } + + return result +} + +// HandlePacket is called by the stack when new packets arrive to this transport +// endpoint. +func (e *endpoint) HandlePacket(r *stack.Route, id stack.TransportEndpointID, vv *buffer.VectorisedView) { + // Get the header then trim it from the view. + hdr := header.UDP(vv.First()) + if int(hdr.Length()) > vv.Size() { + // Malformed packet. + return + } + + vv.TrimFront(header.UDPMinimumSize) + + e.rcvMu.Lock() + + // Drop the packet if our buffer is currently full. + if !e.rcvReady || e.rcvClosed || e.rcvBufSize >= e.rcvBufSizeMax { + e.rcvMu.Unlock() + return + } + + wasEmpty := e.rcvBufSize == 0 + + // Push new packet into receive list and increment the buffer size. + pkt := &udpPacket{ + senderAddress: tcpip.FullAddress{ + NIC: r.NICID(), + Addr: id.RemoteAddress, + Port: hdr.SourcePort(), + }, + } + pkt.data = vv.Clone(pkt.views[:]) + e.rcvList.PushBack(pkt) + e.rcvBufSize += vv.Size() + + e.rcvMu.Unlock() + + // Notify any waiters that there's data to be read now. + if wasEmpty { + e.waiterQueue.Notify(waiter.EventIn) + } +} + +// HandleControlPacket implements stack.TransportEndpoint.HandleControlPacket. +func (e *endpoint) HandleControlPacket(id stack.TransportEndpointID, typ stack.ControlType, extra uint32, vv *buffer.VectorisedView) { +} -- cgit v1.2.3