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package ice
import (
"fmt"
"github.com/pion/stun"
)
func newCandidatePair(local, remote Candidate, controlling bool) *candidatePair {
return &candidatePair{
iceRoleControlling: controlling,
remote: remote,
local: local,
state: CandidatePairStateWaiting,
}
}
// candidatePair represents a combination of a local and remote candidate
type candidatePair struct {
iceRoleControlling bool
remote Candidate
local Candidate
bindingRequestCount uint16
state CandidatePairState
nominated bool
}
func (p *candidatePair) String() string {
if p == nil {
return ""
}
return fmt.Sprintf("prio %d (local, prio %d) %s <-> %s (remote, prio %d)",
p.Priority(), p.local.Priority(), p.local, p.remote, p.remote.Priority())
}
func (p *candidatePair) Equal(other *candidatePair) bool {
if p == nil && other == nil {
return true
}
if p == nil || other == nil {
return false
}
return p.local.Equal(other.local) && p.remote.Equal(other.remote)
}
// RFC 5245 - 5.7.2. Computing Pair Priority and Ordering Pairs
// Let G be the priority for the candidate provided by the controlling
// agent. Let D be the priority for the candidate provided by the
// controlled agent.
// pair priority = 2^32*MIN(G,D) + 2*MAX(G,D) + (G>D?1:0)
func (p *candidatePair) Priority() uint64 {
var g uint32
var d uint32
if p.iceRoleControlling {
g = p.local.Priority()
d = p.remote.Priority()
} else {
g = p.remote.Priority()
d = p.local.Priority()
}
// Just implement these here rather
// than fooling around with the math package
min := func(x, y uint32) uint64 {
if x < y {
return uint64(x)
}
return uint64(y)
}
max := func(x, y uint32) uint64 {
if x > y {
return uint64(x)
}
return uint64(y)
}
cmp := func(x, y uint32) uint64 {
if x > y {
return uint64(1)
}
return uint64(0)
}
// 1<<32 overflows uint32; and if both g && d are
// maxUint32, this result would overflow uint64
return (1<<32-1)*min(g, d) + 2*max(g, d) + cmp(g, d)
}
func (p *candidatePair) Write(b []byte) (int, error) {
return p.local.writeTo(b, p.remote)
}
func (a *Agent) sendSTUN(msg *stun.Message, local, remote Candidate) {
_, err := local.writeTo(msg.Raw, remote)
if err != nil {
a.log.Tracef("failed to send STUN message: %s", err)
}
}
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