Does go-gtp allow to create the GTP headers?

[vggonzalez]

Hi!

I need to go through an already established GTP tunnel. To do so, I need to create the GTP header. I was wondering if your project has any kind of facilities for it. I've been looking through it and so far I couldn't find any or a similar example.

Regards,
Víctor

[wmnsk]

You can create the packet with message.NewTPDU and marshal it into a binary with Marshal(). Then you can write it to UDP conn.

import "github.com/wmnsk/go-gtp/gtpv1/message"

msg := message.NewTPDU(teid, payload)

b, err := msg.Marshal()
if err := nil {
    // ...
}

if _, err := conn.WriteTo(b, raddr); err := nil {
    // ...
}

If you need to set values to more fields in GTPv1 header(other than TEID), create the message from Header struct by yourself instead.

go-gtp/gtpv1/message/header.go

Lines 18 to 27 in 3cac31b

	// Header is a GTPv1 common header.
	type Header struct {
	Flags uint8
	Type uint8
	Length uint16
	TEID uint32
	SequenceNumber uint16
	Reserved uint16
	Payload []byte
	}

msg := &message.Header{
   // ...
}

Hope this helps.

[wmnsk]

@vggonzalez
Let me know when you need more help.