feat: remove NewAckRequest and handle better transaction ACK request

sip/request.go

@@ -214,21 +214,21 @@ func (req *Request) Destination() string {
 	return fmt.Sprintf("%v:%v", host, port)
 }
 
-// NewAckRequest creates ACK request for 2xx INVITE
-// https://tools.ietf.org/html/rfc3261#section-13.2.2.4
-// NOTE: it does not copy Via header. This is left to transport or caller to enforce
-// Deprecated: use DialogClient for building dialogs
-func NewAckRequest(inviteRequest *Request, inviteResponse *Response, body []byte) *Request {
-	Recipient := &inviteRequest.Recipient
-	if contact := inviteResponse.Contact(); contact != nil {
-		Recipient = &contact.Address
-	}
+// newAckRequestNon2xx follows rules as here. This is not dialog ACK instead it is transaction ACK.
+// https://datatracker.ietf.org/doc/html/rfc3261#section-17.1.1.3
+func newAckRequestNon2xx(inviteRequest *Request, inviteResponse *Response, body []byte) *Request {
+	recipient := &inviteRequest.Recipient
 	ackRequest := NewRequest(
 		ACK,
-		*Recipient.Clone(),
+		*recipient.Clone(),
 	)
 	ackRequest.SipVersion = inviteRequest.SipVersion
 
+	// 	The ACK MUST contain a single Via header field, and
+	//  this MUST be equal to the top Via header field of the original
+	//  request.
+	CopyHeaders("Via", inviteRequest, ackRequest)
+
 	if len(inviteRequest.GetHeaders("Route")) > 0 {
 		CopyHeaders("Route", inviteRequest, ackRequest)
 	} else {
@@ -258,42 +258,24 @@ func NewAckRequest(inviteRequest *Request, inviteResponse *Response, body []byte
 		ackRequest.AppendHeader(h.headerClone())
 	}
 
+	// Seq header field in the ACK MUST contain the same
+	//    value for the sequence number as was present in the original request,
+	//    but the method parameter MUST be equal to "ACK"
 	cseq := ackRequest.CSeq()
 	cseq.MethodName = ACK
 
-	/*
-	   	A UAC SHOULD include a Contact header field in any target refresh
-	    requests within a dialog, and unless there is a need to change it,
-	    the URI SHOULD be the same as used in previous requests within the
-	    dialog.  If the "secure" flag is true, that URI MUST be a SIPS URI.
-	    As discussed in Section 12.2.2, a Contact header field in a target
-	    refresh request updates the remote target URI.  This allows a UA to
-	    provide a new contact address, should its address change during the
-	    duration of the dialog.
-	*/
-
 	if h := inviteRequest.Contact(); h != nil {
 		ackRequest.AppendHeader(h.headerClone())
 	}
 
 	ackRequest.SetBody(body)
 	ackRequest.SetTransport(inviteRequest.Transport())
 	ackRequest.SetSource(inviteRequest.Source())
-	// NOTE forcing here destination will be wrong if we have custom Route handling by proxies
-	// ackRequest.SetDestination(inviteRequest.Destination())
-
-	return ackRequest
-}
-
-func newAckRequestNon2xx(inviteRequest *Request, inviteResponse *Response, body []byte) *Request {
-	ackRequest := NewAckRequest(inviteRequest, inviteResponse, body)
-
-	CopyHeaders("Via", inviteRequest, ackRequest)
-	if inviteResponse.IsSuccess() {
-		// update branch, 2xx ACK is separate Tx
-		viaHop := ackRequest.Via()
-		viaHop.Params.Add("branch", GenerateBranch())
-	}
+	// if inviteResponse.IsSuccess() {
+	// 	// update branch, 2xx ACK is separate Tx
+	// 	viaHop := ackRequest.Via()
+	// 	viaHop.Params.Add("branch", GenerateBranch())
+	// }
 	return ackRequest
 }