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package ice
import (
"context"
"fmt"
"hash/crc32"
"net"
"strconv"
"strings"
"sync/atomic"
"time"
"github.com/pion/logging"
"github.com/pion/stun"
)
type candidateBase struct {
id string
networkType NetworkType
candidateType CandidateType
component uint16
address string
port int
relatedAddress *CandidateRelatedAddress
tcpType TCPType
resolvedAddr net.Addr
lastSent atomic.Value
lastReceived atomic.Value
conn net.PacketConn
currAgent *Agent
closeCh chan struct{}
closedCh chan struct{}
foundationOverride string
priorityOverride uint32
}
// Done implements context.Context
func (c *candidateBase) Done() <-chan struct{} {
return c.closeCh
}
// Err implements context.Context
func (c *candidateBase) Err() error {
select {
case <-c.closedCh:
return ErrRunCanceled
default:
return nil
}
}
// Deadline implements context.Context
func (c *candidateBase) Deadline() (deadline time.Time, ok bool) {
return time.Time{}, false
}
// Value implements context.Context
func (c *candidateBase) Value(key interface{}) interface{} {
return nil
}
// ID returns Candidate ID
func (c *candidateBase) ID() string {
return c.id
}
func (c *candidateBase) Foundation() string {
if c.foundationOverride != "" {
return c.foundationOverride
}
return fmt.Sprintf("%d", crc32.ChecksumIEEE([]byte(c.Type().String()+c.address+c.networkType.String())))
}
// Address returns Candidate Address
func (c *candidateBase) Address() string {
return c.address
}
// Port returns Candidate Port
func (c *candidateBase) Port() int {
return c.port
}
// Type returns candidate type
func (c *candidateBase) Type() CandidateType {
return c.candidateType
}
// NetworkType returns candidate NetworkType
func (c *candidateBase) NetworkType() NetworkType {
return c.networkType
}
// Component returns candidate component
func (c *candidateBase) Component() uint16 {
return c.component
}
func (c *candidateBase) SetComponent(component uint16) {
c.component = component
}
// LocalPreference returns the local preference for this candidate
func (c *candidateBase) LocalPreference() uint16 {
if c.NetworkType().IsTCP() {
// RFC 6544, section 4.2
//
// In Section 4.1.2.1 of [RFC5245], a recommended formula for UDP ICE
// candidate prioritization is defined. For TCP candidates, the same
// formula and candidate type preferences SHOULD be used, and the
// RECOMMENDED type preferences for the new candidate types defined in
// this document (see Section 5) are 105 for NAT-assisted candidates and
// 75 for UDP-tunneled candidates.
//
// (...)
//
// With TCP candidates, the local preference part of the recommended
// priority formula is updated to also include the directionality
// (active, passive, or simultaneous-open) of the TCP connection. The
// RECOMMENDED local preference is then defined as:
//
// local preference = (2^13) * direction-pref + other-pref
//
// The direction-pref MUST be between 0 and 7 (both inclusive), with 7
// being the most preferred. The other-pref MUST be between 0 and 8191
// (both inclusive), with 8191 being the most preferred. It is
// RECOMMENDED that the host, UDP-tunneled, and relayed TCP candidates
// have the direction-pref assigned as follows: 6 for active, 4 for
// passive, and 2 for S-O. For the NAT-assisted and server reflexive
// candidates, the RECOMMENDED values are: 6 for S-O, 4 for active, and
// 2 for passive.
//
// (...)
//
// If any two candidates have the same type-preference and direction-
// pref, they MUST have a unique other-pref. With this specification,
// this usually only happens with multi-homed hosts, in which case
// other-pref is the preference for the particular IP address from which
// the candidate was obtained. When there is only a single IP address,
// this value SHOULD be set to the maximum allowed value (8191).
var otherPref uint16 = 8191
directionPref := func() uint16 {
switch c.Type() {
case CandidateTypeHost, CandidateTypeRelay:
switch c.tcpType {
case TCPTypeActive:
return 6
case TCPTypePassive:
return 4
case TCPTypeSimultaneousOpen:
return 2
case TCPTypeUnspecified:
return 0
}
case CandidateTypePeerReflexive, CandidateTypeServerReflexive:
switch c.tcpType {
case TCPTypeSimultaneousOpen:
return 6
case TCPTypeActive:
return 4
case TCPTypePassive:
return 2
case TCPTypeUnspecified:
return 0
}
case CandidateTypeUnspecified:
return 0
}
return 0
}()
return (1<<13)*directionPref + otherPref
}
return defaultLocalPreference
}
// RelatedAddress returns *CandidateRelatedAddress
func (c *candidateBase) RelatedAddress() *CandidateRelatedAddress {
return c.relatedAddress
}
func (c *candidateBase) TCPType() TCPType {
return c.tcpType
}
// start runs the candidate using the provided connection
func (c *candidateBase) start(a *Agent, conn net.PacketConn, initializedCh <-chan struct{}) {
if c.conn != nil {
c.agent().log.Warn("Can't start already started candidateBase")
return
}
c.currAgent = a
c.conn = conn
c.closeCh = make(chan struct{})
c.closedCh = make(chan struct{})
go c.recvLoop(initializedCh)
}
func (c *candidateBase) recvLoop(initializedCh <-chan struct{}) {
defer func() {
close(c.closedCh)
}()
select {
case <-initializedCh:
case <-c.closeCh:
return
}
log := c.agent().log
buffer := make([]byte, receiveMTU)
for {
n, srcAddr, err := c.conn.ReadFrom(buffer)
if err != nil {
return
}
handleInboundCandidateMsg(c, c, buffer[:n], srcAddr, log)
}
}
func handleInboundCandidateMsg(ctx context.Context, c Candidate, buffer []byte, srcAddr net.Addr, log logging.LeveledLogger) {
if stun.IsMessage(buffer) {
m := &stun.Message{
Raw: make([]byte, len(buffer)),
}
// Explicitly copy raw buffer so Message can own the memory.
copy(m.Raw, buffer)
if err := m.Decode(); err != nil {
log.Warnf("Failed to handle decode ICE from %s to %s: %v", c.addr(), srcAddr, err)
return
}
err := c.agent().run(ctx, func(ctx context.Context, agent *Agent) {
agent.handleInbound(m, c, srcAddr)
})
if err != nil {
log.Warnf("Failed to handle message: %v", err)
}
return
}
if !c.agent().validateNonSTUNTraffic(c, srcAddr) {
log.Warnf("Discarded message from %s, not a valid remote candidate", c.addr())
return
}
// NOTE This will return packetio.ErrFull if the buffer ever manages to fill up.
if _, err := c.agent().buffer.Write(buffer); err != nil {
log.Warnf("failed to write packet")
}
}
// close stops the recvLoop
func (c *candidateBase) close() error {
// If conn has never been started will be nil
if c.Done() == nil {
return nil
}
// Assert that conn has not already been closed
select {
case <-c.Done():
return nil
default:
}
var firstErr error
// Unblock recvLoop
close(c.closeCh)
if err := c.conn.SetDeadline(time.Now()); err != nil {
firstErr = err
}
// Close the conn
if err := c.conn.Close(); err != nil && firstErr == nil {
firstErr = err
}
if firstErr != nil {
return firstErr
}
// Wait until the recvLoop is closed
<-c.closedCh
return nil
}
func (c *candidateBase) writeTo(raw []byte, dst Candidate) (int, error) {
n, err := c.conn.WriteTo(raw, dst.addr())
if err != nil {
c.agent().log.Warnf("%s: %v", errSendPacket, err)
return n, nil
}
c.seen(true)
return n, nil
}
// Priority computes the priority for this ICE Candidate
func (c *candidateBase) Priority() uint32 {
if c.priorityOverride != 0 {
return c.priorityOverride
}
// The local preference MUST be an integer from 0 (lowest preference) to
// 65535 (highest preference) inclusive. When there is only a single IP
// address, this value SHOULD be set to 65535. If there are multiple
// candidates for a particular component for a particular data stream
// that have the same type, the local preference MUST be unique for each
// one.
return (1<<24)*uint32(c.Type().Preference()) +
(1<<8)*uint32(c.LocalPreference()) +
uint32(256-c.Component())
}
// Equal is used to compare two candidateBases
func (c *candidateBase) Equal(other Candidate) bool {
return c.NetworkType() == other.NetworkType() &&
c.Type() == other.Type() &&
c.Address() == other.Address() &&
c.Port() == other.Port() &&
c.TCPType() == other.TCPType() &&
c.RelatedAddress().Equal(other.RelatedAddress())
}
// String makes the candidateBase printable
func (c *candidateBase) String() string {
return fmt.Sprintf("%s %s %s:%d%s", c.NetworkType(), c.Type(), c.Address(), c.Port(), c.relatedAddress)
}
// LastReceived returns a time.Time indicating the last time
// this candidate was received
func (c *candidateBase) LastReceived() time.Time {
lastReceived := c.lastReceived.Load()
if lastReceived == nil {
return time.Time{}
}
return lastReceived.(time.Time)
}
func (c *candidateBase) setLastReceived(t time.Time) {
c.lastReceived.Store(t)
}
// LastSent returns a time.Time indicating the last time
// this candidate was sent
func (c *candidateBase) LastSent() time.Time {
lastSent := c.lastSent.Load()
if lastSent == nil {
return time.Time{}
}
return lastSent.(time.Time)
}
func (c *candidateBase) setLastSent(t time.Time) {
c.lastSent.Store(t)
}
func (c *candidateBase) seen(outbound bool) {
if outbound {
c.setLastSent(time.Now())
} else {
c.setLastReceived(time.Now())
}
}
func (c *candidateBase) addr() net.Addr {
return c.resolvedAddr
}
func (c *candidateBase) agent() *Agent {
return c.currAgent
}
func (c *candidateBase) context() context.Context {
return c
}
func (c *candidateBase) copy() (Candidate, error) {
return UnmarshalCandidate(c.Marshal())
}
// Marshal returns the string representation of the ICECandidate
func (c *candidateBase) Marshal() string {
val := c.Foundation()
if val == " " {
val = ""
}
val = fmt.Sprintf("%s %d %s %d %s %d typ %s",
val,
c.Component(),
c.NetworkType().NetworkShort(),
c.Priority(),
c.Address(),
c.Port(),
c.Type())
if c.tcpType != TCPTypeUnspecified {
val += fmt.Sprintf(" tcptype %s", c.tcpType.String())
}
if r := c.RelatedAddress(); r != nil && r.Address != "" && r.Port != 0 {
val = fmt.Sprintf("%s raddr %s rport %d",
val,
r.Address,
r.Port)
}
return val
}
// UnmarshalCandidate creates a Candidate from its string representation
func UnmarshalCandidate(raw string) (Candidate, error) {
split := strings.Fields(raw)
// Foundation not specified: not RFC 8445 compliant but seen in the wild
if len(raw) != 0 && raw[0] == ' ' {
split = append([]string{" "}, split...)
}
if len(split) < 8 {
return nil, fmt.Errorf("%w (%d)", errAttributeTooShortICECandidate, len(split))
}
// Foundation
foundation := split[0]
// Component
rawComponent, err := strconv.ParseUint(split[1], 10, 16)
if err != nil {
return nil, fmt.Errorf("%w: %v", errParseComponent, err)
}
component := uint16(rawComponent)
// Protocol
protocol := split[2]
// Priority
priorityRaw, err := strconv.ParseUint(split[3], 10, 32)
if err != nil {
return nil, fmt.Errorf("%w: %v", errParsePriority, err)
}
priority := uint32(priorityRaw)
// Address
address := split[4]
// Port
rawPort, err := strconv.ParseUint(split[5], 10, 16)
if err != nil {
return nil, fmt.Errorf("%w: %v", errParsePort, err)
}
port := int(rawPort)
typ := split[7]
relatedAddress := ""
relatedPort := 0
tcpType := TCPTypeUnspecified
if len(split) > 8 {
split = split[8:]
if split[0] == "raddr" {
if len(split) < 4 {
return nil, fmt.Errorf("%w: incorrect length", errParseRelatedAddr)
}
// RelatedAddress
relatedAddress = split[1]
// RelatedPort
rawRelatedPort, parseErr := strconv.ParseUint(split[3], 10, 16)
if parseErr != nil {
return nil, fmt.Errorf("%w: %v", errParsePort, parseErr)
}
relatedPort = int(rawRelatedPort)
} else if split[0] == "tcptype" {
if len(split) < 2 {
return nil, fmt.Errorf("%w: incorrect length", errParseTypType)
}
tcpType = NewTCPType(split[1])
}
}
switch typ {
case "host":
return NewCandidateHost(&CandidateHostConfig{"", protocol, address, port, component, priority, foundation, tcpType})
case "srflx":
return NewCandidateServerReflexive(&CandidateServerReflexiveConfig{"", protocol, address, port, component, priority, foundation, relatedAddress, relatedPort})
case "prflx":
return NewCandidatePeerReflexive(&CandidatePeerReflexiveConfig{"", protocol, address, port, component, priority, foundation, relatedAddress, relatedPort})
case "relay":
return NewCandidateRelay(&CandidateRelayConfig{"", protocol, address, port, component, priority, foundation, relatedAddress, relatedPort, "", nil})
default:
}
return nil, fmt.Errorf("%w (%s)", ErrUnknownCandidateTyp, typ)
}
