seydx
76 lines
1.6 KiB
Go
76 lines
1.6 KiB
Go
package rtsp
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import (
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"fmt"
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"net"
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"sync"
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)
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var mu sync.Mutex
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type UDPPortPair struct {
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RTPListener *net.UDPConn
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RTCPListener *net.UDPConn
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RTPPort int
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RTCPPort int
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}
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func (p *UDPPortPair) Close() {
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if p.RTPListener != nil {
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_ = p.RTPListener.Close()
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}
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if p.RTCPListener != nil {
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_ = p.RTCPListener.Close()
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}
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}
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func GetUDPPorts(ip net.IP, maxAttempts int) (*UDPPortPair, error) {
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mu.Lock()
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defer mu.Unlock()
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if ip == nil {
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ip = net.IPv4(0, 0, 0, 0)
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}
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for i := 0; i < maxAttempts; i++ {
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// Get a random even port from the OS
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tempListener, err := net.ListenUDP("udp", &net.UDPAddr{IP: ip, Port: 0})
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if err != nil {
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continue
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}
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addr := tempListener.LocalAddr().(*net.UDPAddr)
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basePort := addr.Port
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tempListener.Close()
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// 11. RTP over Network and Transport Protocols (https://www.ietf.org/rfc/rfc3550.txt)
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// For UDP and similar protocols,
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// RTP SHOULD use an even destination port number and the corresponding
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// RTCP stream SHOULD use the next higher (odd) destination port number
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if basePort%2 == 1 {
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basePort--
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}
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// Try to bind both ports
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rtpListener, err := net.ListenUDP("udp", &net.UDPAddr{IP: ip, Port: basePort})
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if err != nil {
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continue
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}
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rtcpListener, err := net.ListenUDP("udp", &net.UDPAddr{IP: ip, Port: basePort + 1})
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if err != nil {
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rtpListener.Close()
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continue
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}
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return &UDPPortPair{
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RTPListener: rtpListener,
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RTCPListener: rtcpListener,
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RTPPort: basePort,
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RTCPPort: basePort + 1,
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}, nil
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}
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return nil, fmt.Errorf("failed to allocate consecutive UDP ports after %d attempts", maxAttempts)
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}
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