library/SIP_Templates.ttcn

module SIP_Templates {

import from SIPmsg_Types all;
import from TCCConversion_Functions all;
import from TCCOpenSecurity_Functions all;
import from TCCDateTime_Functions all;
import from Native_Functions all;
import from Osmocom_Types all;
import from Misc_Helpers all;

/* wrapper type to encapsulate the Addr_Union + parameter list used in From, To. ... */
type record SipAddr {
	Addr_Union 		addr,
	SemicolonParam_List	params optional
}

const charstring c_SIP_VERSION := "SIP/2.0";

template (value) GenericParam ts_Param(template (value) charstring id,
				       template (omit) charstring paramValue := omit) := {
	id := id,
	paramValue := paramValue
}
template (present) GenericParam tr_Param(template (present) charstring id := ?,
					 template charstring paramValue := *) := {
	id := id,
	paramValue := paramValue
}
function f_ts_Param_omit(template (value) charstring id,
			 template (omit) charstring paramValue := omit)
	return template (omit) GenericParam
{
	if (istemplatekind(paramValue, "omit")) {
		return omit;
	}
	return ts_Param(id, paramValue);
}

template (value) SipUrl ts_SipUrl(template (value) HostPort host_port,
				  template (omit) UserInfo user_info := omit,
				  template (value) charstring scheme := "sip") := {
	scheme := scheme,
	userInfo := user_info,
	hostPort := host_port,
	urlParameters := omit,
	headers := omit
}
template (present) SipUrl tr_SipUrl(template (present) HostPort host_port := ?,
				    template UserInfo user_info := *,
				    template (present) charstring scheme := "sip") := {
	scheme := scheme,
	userInfo := user_info,
	hostPort := host_port,
	urlParameters := *,
	headers := *
}

template (value) SipUrl ts_SipUrlHost(template (value) charstring host,
				      template (omit) integer portField := omit,
				      template (value) charstring scheme := "sip")
	:= ts_SipUrl(ts_HostPort(host, portField), scheme := scheme);

function ts_SipUrl_from_Addr_Union(template (value) Addr_Union au)
return template (value) SipUrl {
	if (ischosen(au.nameAddr)) {
		return au.nameAddr.addrSpec;
	} else { /* au.addrSpecUnion */
		return au.addrSpecUnion;
	}
}

// [20.5]
template (present) Allow tr_Allow(template Method_List methods := *) := {
	fieldName := ALLOW_E,
	methods := methods
}
template (value) Allow ts_Allow(template (omit) Method_List methods := omit) := {
	fieldName := ALLOW_E,
	methods := methods
}

template (present) Credentials tr_Credentials_DigestResponse(template (present) CommaParam_List digestResponse) := {
	digestResponse := digestResponse
}
template (value) Credentials ts_Credentials_DigestResponse(template (value) CommaParam_List digestResponse) := {
	digestResponse := digestResponse
}

template (value) Credentials ts_Credentials_DigestResponseMD5(
			template (value) charstring username,
			template (value) charstring realm,
			template (value) charstring nonce,
			template (value) charstring uri,
			template (value) charstring response,
			template (value) charstring opaque,
			template (value) charstring algorithm := "MD5",
			template (value) charstring qop := "auth",
			template (omit) charstring cnonce := omit,
			template (omit) charstring nc := omit
			) := {
	digestResponse := {
		// Already added by digestResponse automatically:
		//ts_Param("Digest", omit),
		ts_Param("username", f_sip_str_quote(username)),
		ts_Param("realm", f_sip_str_quote(realm)),
		ts_Param("nonce", f_sip_str_quote(nonce)),
		ts_Param("uri", f_sip_str_quote(uri)),
		ts_Param("response", f_sip_str_quote(response)),
		ts_Param("opaque", f_sip_str_quote(opaque)),
		ts_Param("algorithm", algorithm),
		ts_Param("qop", qop),
		// FIXME: If "omit" is passed, these below end up in;
		// "Dynamic test case error: Performing a valueof or send operation on a non-specific template of type @SIPmsg_Types.GenericParam"
		f_ts_Param_omit("cnonce", f_sip_str_quote(cnonce)),
		f_ts_Param_omit("nc", nc)
	}
}

template (value) Credentials ts_Credentials_OtherAuth(template (value) OtherAuth otherResponse) := {
	otherResponse := otherResponse
}

template (present) Authorization tr_Authorization(template (present) Credentials body) := {
	fieldName := AUTHORIZATION_E,
	body := body
}
template (value) Authorization ts_Authorization(template (value) Credentials body) := {
	fieldName := AUTHORIZATION_E,
	body := body
}

// [20.10]
template (present) NameAddr tr_NameAddr(template (present) SipUrl addrSpec := ?,
				      template charstring displayName := *) := {
	displayName := displayName,
	addrSpec := addrSpec
}
template (value) NameAddr ts_NameAddr(template (value) SipUrl addrSpec,
				      template (omit) charstring displayName := omit) := {
	displayName := displayName,
	addrSpec := addrSpec
}

template (present) Addr_Union tr_Addr_Union_NameAddr(template (present) NameAddr nameAddr := ?) := {
	nameAddr := nameAddr
}
template (value) Addr_Union ts_Addr_Union_NameAddr(template (value) NameAddr nameAddr) := {
	nameAddr := nameAddr
}

template (present) Addr_Union tr_Addr_Union_SipUrl(template (present) SipUrl sipUrl := ?) := {
	addrSpecUnion := sipUrl
}
template (value) Addr_Union ts_Addr_Union_SipUrl(template (value) SipUrl sipUrl) := {
	addrSpecUnion := sipUrl
}


template (present) ContactAddress tr_ContactAddress(template (present) Addr_Union addressField := ?,
						  template SemicolonParam_List contactParams := *) := {
	addressField := addressField,
	contactParams := contactParams
}
template (value) ContactAddress ts_ContactAddress(template (value) Addr_Union addressField,
						  template (omit) SemicolonParam_List contactParams := omit) := {
	addressField := addressField,
	contactParams := contactParams
}

template (present) Contact tr_Contact(template (present) ContactAddress_List contactAddresses := ?) := {
	fieldName := CONTACT_E,
	contactBody := {
		contactAddresses := contactAddresses
	}
}
template (value) Contact ts_Contact(template (value) ContactAddress_List contactAddresses) := {
	fieldName := CONTACT_E,
	contactBody := {
		contactAddresses := contactAddresses
	}
}

template (value) Contact ts_ContactWildcard := {
	fieldName := CONTACT_E,
	contactBody := {
		wildcard := "*"
	}
}

template (present) Contact tr_Contact_SipAddr(template (present) SipAddr contact_addr := ?)
	:= tr_Contact({ tr_ContactAddress(contact_addr.addr, contact_addr.params) });

private function f_tr_Contact_SipAddr(template SipAddr contact_addr) return template Contact
{
	if (istemplatekind(contact_addr, "omit")) {
		return omit;
	} else if (istemplatekind(contact_addr, "*")) {
		return *;
	}
	return tr_Contact_SipAddr(contact_addr);
}

template (value) Contact ts_Contact_SipAddr(template (value) SipAddr contact_addr)
	:= ts_Contact({ ts_ContactAddress(contact_addr.addr, contact_addr.params) });
private function ts_Contact_SipAddr_omit(template (omit) SipAddr contact_addr := omit) return template (omit) Contact
{
	if (istemplatekind(contact_addr, "omit")) {
		return omit;
	}
	return ts_Contact_SipAddr(contact_addr);
}


// [20.14]
template (value) ContentLength ts_ContentLength(template (value) integer len := 0) := {
	fieldName := CONTENT_LENGTH_E,
	len := len
}
template (present) ContentLength tr_ContentLength(template (present) integer len := ?) := {
	fieldName := CONTENT_LENGTH_E,
	len := len
}

// [20.19]
template (value) Expires ts_Expires(template (value) DeltaSec deltaSec := "7200") := {
	fieldName := EXPIRES_E,
	deltaSec := deltaSec
}

// [RFC3455 5.4] + 3GPP 24.229 V8.7.0
template (present) Access_net_spec tr_Access_net_spec(template (present) charstring access_type := ?,
						      template SemicolonParam_List access_info := *) := {
	access_type := access_type,
	access_info := access_info
}
template (present) Access_net_spec tr_Access_net_spec_EUTRAN(template (present) charstring uli_str := ?) := {
	access_type := "3GPP-E-UTRAN-FDD",
	access_info := {tr_Param("utran-cell-id-3gpp", uli_str)}
}

// [RFC3455 5.4] + 3GPP 24.229 V8.7.0
template (present) P_Access_Network_Info tr_P_Access_Network_Info(template (present) Access_net_spec_list access_net_specs := ?) := {
	fieldName := P_ACCESS_NETWORK_INFO,
	access_net_specs := access_net_specs
}

// [RFC3455 4.1]
template (present) P_Assoc_uri_spec tr_P_Assoc_uri_spec(template (present) NameAddr p_asso_uri := ?,
							template SemicolonParam_List ai_params := *) := {
	p_asso_uri := p_asso_uri,
	ai_params := ai_params
}
template (value) P_Assoc_uri_spec ts_P_Assoc_uri_spec(template (value) NameAddr p_asso_uri,
						      template (omit) SemicolonParam_List ai_params := omit) := {
	p_asso_uri := p_asso_uri,
	ai_params := ai_params
}

// [RFC3455 4.1]
template (present) P_Associated_Uri tr_P_Associated_Uri(template (present) P_Assoc_uri_spec_list p_assoc_uris := ?) := {
	fieldName := P_ASSOCIATED_URI,
	p_assoc_uris := p_assoc_uris
}
template (value) P_Associated_Uri ts_P_Associated_Uri(template (value) P_Assoc_uri_spec_list p_assoc_uris := {}) := {
	fieldName := P_ASSOCIATED_URI,
	p_assoc_uris := p_assoc_uris
}

// [20.32]
template (value) Require ts_Require(template (value) OptionTag_List optionsTags := {}) := {
	fieldName := REQUIRE_E,
	optionsTags := optionsTags
}
template (present) Require tr_Require(template (present) OptionTag_List optionsTags := ?) := {
	fieldName := REQUIRE_E,
	optionsTags := optionsTags
}

// [20.35 RFC2616 14.38]
template (value) Server ts_Server(template (value) ServerVal_List serverBody := {}) := {
	fieldName := SERVER_E,
	serverBody := serverBody
}
template (present) Server tr_Server(template (present) ServerVal_List serverBody := ?) := {
	fieldName := SERVER_E,
	serverBody := serverBody
}

// [20.37]
template (value) Supported ts_Supported(template (value) OptionTag_List optionsTags := {}) := {
	fieldName := SUPPORTED_E,
	optionsTags := optionsTags
}
template (present) Supported tr_Supported(template (present) OptionTag_List optionsTags := ?) := {
	fieldName := SUPPORTED_E,
	optionsTags := optionsTags
}

// [20.41 RFC2616 14.43]
template (value) UserAgent ts_UserAgent(template (value) ServerVal_List userAgentBody := {}) := {
	fieldName := USER_AGENT_E,
	userAgentBody := userAgentBody
}
template (present) UserAgent tr_UserAgent(template (present) ServerVal_List userAgentBody := ?) := {
	fieldName := USER_AGENT_E,
	userAgentBody := userAgentBody
}


template (value) SipAddr ts_SipAddr(template (value) HostPort host_port,
				    template (omit) UserInfo user_info := omit,
				    template (omit) charstring displayName := omit,
				    template (omit) SemicolonParam_List params := omit) := {
	addr := {
		nameAddr := {
			displayName := displayName,
			addrSpec := ts_SipUrl(host_port, user_info)
		}
	},
	params := params
}
template (present) SipAddr tr_SipAddr(template (present) HostPort host_port := ?,
				      template UserInfo user_info := *,
				      template charstring displayName := *,
				      template SemicolonParam_List params := *) := {
	addr := {
		nameAddr := {
			displayName := displayName,
			addrSpec := tr_SipUrl(host_port, user_info)
		}
	},
	params := params
}

/* build a receive template from a value: substitute '*' for omit */
function tr_SipUrl_from_val(template (value) SipUrl tin) return template (present) SipUrl {
	var template (present) SipUrl ret := tin;

	/* if the port number is 5060, it may be omitted */
	if (ispresent(tin.hostPort.portField) and
	    valueof(tin.hostPort.portField) == 5060) {
		ret.hostPort.portField := 5060 ifpresent;
	}
	if (not ispresent(tin.userInfo.password)) {
		ret.userInfo.password := *;
	}

	return ret;
}
function tr_SipAddr_from_val(template (value) SipAddr tin) return template (present) SipAddr {
	var template (present) SipAddr ret := tin;

	if (not ispresent(tin.addr.nameAddr.displayName)) {
		ret.addr.nameAddr.displayName := *;
	} else if (f_str_tolower(f_sip_str_unquote(tin.addr.nameAddr.displayName)) == "anonymous") {
		/* if the user is Anonymous, it may be omitted */
		ret.addr.nameAddr.displayName := tin.addr.nameAddr.displayName ifpresent;
	}

	ret.addr.nameAddr.addrSpec := tr_SipUrl_from_val(tin.addr.nameAddr.addrSpec);

	if (not ispresent(tin.params)) {
		ret.params := *;
	}
	return ret;
}

function ts_SipAddr_from_Addr_Union(template (value) Addr_Union au,
				    template (omit) SemicolonParam_List	params := omit)
return template (value) SipAddr {
	var template (value) SipUrl addrSpec := ts_SipUrl_from_Addr_Union(au);
	var template (omit) charstring displayName;

	if (ischosen(au.nameAddr)) {
		displayName := au.nameAddr.displayName;
	} else { /* au.addrSpecUnion */
		displayName := omit
	}

	return ts_SipAddr(addrSpec.hostPort,
			  addrSpec.userInfo,
			  displayName,
			  params);
}

template (value) HostPort ts_HostPort(template (omit) charstring host := omit,
				      template (omit) integer portField := omit) := {
	host := host,
	portField := portField
}

template (present) HostPort tr_HostPort(template charstring host := *,
					template integer portField := *) := {
	host := host,
	portField := portField
}
function f_tr_HostPort(template charstring host := *,
		       template integer portField := *)
return template (present) HostPort {
	return f_tr_HostPort_opt_defport(tr_HostPort(host, portField));
}
function f_tr_HostPort_opt_defport(template (present) HostPort hp) return template (present) HostPort {
	var template (present) HostPort hpout := hp;
	/* if the port number is 5060, it may be omitted */
	if (isvalue(hp.portField) and valueof(hp.portField) == 5060) {
		hpout.portField := 5060 ifpresent;
	}
	return hpout;
}

function f_tr_SipUrl_opt_defport(template (present) SipUrl url) return template (present) SipUrl {
	var template (present) SipUrl urlout := url;
	urlout.hostPort := f_tr_HostPort_opt_defport(url.hostPort);
	return urlout;
}

template (value) UserInfo ts_UserInfo(template (value) charstring userOrTelephoneSubscriber,
				      template (omit) charstring password := omit) := {
	userOrTelephoneSubscriber := userOrTelephoneSubscriber,
	password := password
}
template (present) UserInfo tr_UserInfo(template (present) charstring userOrTelephoneSubscriber := ?,
					template charstring password := *) := {
	userOrTelephoneSubscriber := userOrTelephoneSubscriber,
	password := password
}

template (value) RequestLine ts_SIP_ReqLine(Method method,
					    template (value) SipUrl uri,
					    charstring ver := c_SIP_VERSION) := {
	method := method,
	requestUri := uri,
	sipVersion := ver
}
template (present) RequestLine tr_SIP_ReqLine(template (present) Method method := ?,
					      template (present) SipUrl uri := ?,
					      template (present) charstring ver := c_SIP_VERSION) := {
	method := method,
	requestUri := uri,
	sipVersion := ver
}

template (value) StatusLine ts_SIP_StatusLine(integer status_code, charstring reason) := {
	sipVersion := "SIP/2.0",
	statusCode := status_code,
	reasonPhrase := reason
}
template (present) StatusLine tr_SIP_StatusLine(template integer status_code,
						template charstring reason) := {
	sipVersion := "SIP/2.0",
	statusCode := status_code,
	reasonPhrase := reason
}


template (value) PDU_SIP_Request ts_SIP_req(template (value) RequestLine rl) := {
	requestLine := rl,
	msgHeader := c_SIP_msgHeader_empty,
	messageBody := omit,
	payload := omit
}

const Method_List c_SIP_defaultMethods := {
	"INVITE", "ACK", "BYE", "CANCEL", "OPTIONS", "PRACK", "MESSAGE", "SUBSCRIBE",
	"NOTIFY", "REFER", "UPDATE" };

private function f_ContentTypeOrOmit(template (omit) ContentType ct, template (omit) charstring body)
return template (omit) ContentType {
	/* if user explicitly stated no content type */
	if (istemplatekind(ct, "omit")) {
		return omit;
	}
	/* if there's no body, then there's no content-type either */
	if (istemplatekind(body, "omit")) {
		return omit;
	}
	return ct;
}

private function f_ContentLength(template (omit) charstring body)
return template (value) ContentLength {
	/* rfc3261 20.14: "If no body is present in a message, then the
	 * Content-Length header field value MUST be set to zero." */
	if (istemplatekind(body, "omit")) {
		return ts_ContentLength(0);
	}
	return ts_ContentLength(lengthof(body));
}

template (value) ContentType ts_CT_SDP := {
	fieldName := CONTENT_TYPE_E,
	mediaType := "application/sdp"
};

template (value) Via ts_Via_from(template (value) HostPort addr,
				 template (value) charstring transport := "UDP") := {
	fieldName := VIA_E,
	viaBody := {
		{
			sentProtocol := { "SIP", "2.0", transport },
			sentBy := addr,
			viaParams := omit
		}
	}
}
template (present) Via tr_Via_from(template (present) HostPort host_port := ?,
				   template (present) charstring transport := ?,
				   template SemicolonParam_List viaParams := *) := {
	fieldName := VIA_E,
	viaBody := {
		{
			sentProtocol := { "SIP", "2.0", ? },
			sentBy := host_port,
			viaParams := viaParams
		}
	}
}

template (present) OtherAuth
tr_OtherAuth(template (present) charstring authScheme := ?,
	     template (present) CommaParam_List authParams := ?) := {
	authScheme := authScheme,
	authParams := authParams
}

template (value) OtherAuth
ts_OtherAuth(template (value) charstring authScheme,
	     template (value) CommaParam_List authParams) := {
	authScheme := authScheme,
	authParams := authParams
}

template (present) Challenge
tr_Challenge_digestCln(template (present) CommaParam_List digestCln := ?) := {
	digestCln := digestCln
}

template (value) Challenge
ts_Challenge_digestCln(template (value) CommaParam_List digestCln) := {
	digestCln := digestCln
}

template (present) Challenge
tr_Challenge_otherChallenge(template (present) OtherAuth otherChallenge := ?) := {
	otherChallenge := otherChallenge
}

template (value) Challenge
ts_Challenge_otherChallenge(template (value) OtherAuth otherChallenge) := {
	otherChallenge := otherChallenge
}

template (present) WwwAuthenticate
tr_WwwAuthenticate(template (present) Challenge_list challenge := ?) := {
	fieldName := WWW_AUTHENTICATE_E,
	challenge := challenge
}

template (value) WwwAuthenticate
ts_WwwAuthenticate(template (value) Challenge_list challenge) := {
	fieldName := WWW_AUTHENTICATE_E,
	challenge := challenge
}

// RFC3329
template (present) Security_client
tr_Security_client(template (present) Security_mechanism_list sec_mechanism_list := ?) := {
	fieldName := SECURITY_CLIENT_E,
	sec_mechanism_list := sec_mechanism_list
}
template (value) Security_client
ts_Security_client(template (value) Security_mechanism_list sec_mechanism_list) := {
	fieldName := SECURITY_CLIENT_E,
	sec_mechanism_list := sec_mechanism_list
}

template (present) Security_server
tr_Security_server(template (present) Security_mechanism_list sec_mechanism_list := ?) := {
	fieldName := SECURITY_SERVER_E,
	sec_mechanism_list := sec_mechanism_list
}
template (value) Security_server
ts_Security_server(template (value) Security_mechanism_list sec_mechanism_list) := {
	fieldName := SECURITY_SERVER_E,
	sec_mechanism_list := sec_mechanism_list
}

template (present) Security_mechanism
tr_Security_mechanism(template (present) charstring name := ?,
		      template SemicolonParam_List params := *) := {
	mechanism_name := name,
	mechanism_params := params
}
template (value) Security_mechanism
ts_Security_mechanism(template (value) charstring name,
		      template (omit) SemicolonParam_List params := omit) := {
	mechanism_name := name,
	mechanism_params := params
}

template (value) MessageHeader ts_SIP_msgHeader_empty := c_SIP_msgHeader_empty;
template (value) MessageHeader
ts_SIP_msgh_std(template (value) CallidString call_id,
		template (value) SipAddr from_addr,
		template (value) SipAddr to_addr,
		template (omit) Contact contact,
		template (value) charstring method,
		template (value) integer seq_nr,
		template (value) Via via,
		template (omit) ContentLength content_length := ts_ContentLength(0),
		template (omit) ContentType content_type := omit,
		template (omit)Authorization authorization := omit,
		template (omit) Allow allow := ts_Allow(c_SIP_defaultMethods),
		template (omit) Expires expires := omit,
		template (omit) P_Associated_Uri p_associated_uri := omit,
		template (omit) Require require := omit,
		template (omit) Security_client security_client := omit,
		template (omit) Security_server security_server := omit,
		template (omit) Server server := omit,
		template (omit) Supported supported := omit,
		template (omit) UserAgent userAgent := ts_UserAgent({ "osmo-ttcn3-hacks/0.23" }),
		template (omit) WwwAuthenticate wwwAuthenticate := omit
	) modifies ts_SIP_msgHeader_empty := {
	allow := allow,
	authorization := authorization,
	callId := {
		fieldName := CALL_ID_E,
		callid := call_id
	},
	contact := contact,
	contentLength := content_length,
	contentType := content_type,
	cSeq := {
		fieldName := CSEQ_E,
		seqNumber := seq_nr,
		method := method
	},
	expires := expires,
	fromField := {
		fieldName := FROM_E,
		addressField := from_addr.addr,
		fromParams := from_addr.params
	},
	p_associated_uri := p_associated_uri,
	require := require,
	security_client := security_client,
	security_server := security_server,
	server := server,
	supported := supported,
	toField := {
		fieldName := TO_E,
		addressField := to_addr.addr,
		toParams := to_addr.params
	},
	userAgent := userAgent,
	via := via,
	wwwAuthenticate := wwwAuthenticate
}

template (present) MessageHeader
tr_SIP_msgh_std(template CallidString call_id,
		template SipAddr from_addr,
		template SipAddr to_addr,
		template Contact contact,
		template (present) Via via := tr_Via_from(?),
		template charstring method,
		template integer seq_nr := ?,
		template ContentLength content_length := *,
		template ContentType content_type := *,
		template Allow allow := *,
		template Authorization authorization := *,
		template Expires expires := *,
		template P_Associated_Uri p_associated_uri := *,
		template Require require := *,
		template Security_client security_client := *,
		template Security_server security_server := *,
		template Server server := *,
		template Supported supported := *,
		template UserAgent userAgent := *,
		template WwwAuthenticate wwwAuthenticate := *
		) modifies t_SIP_msgHeader_any := {
	allow := allow,
	authorization := authorization,
	callId := {
		fieldName := CALL_ID_E,
		callid := call_id
	},
	contact := contact,
	contentLength := content_length,
	contentType := content_type,
	cSeq := {
		fieldName := CSEQ_E,
		seqNumber := seq_nr,
		method := method
	},
	expires := expires,
	fromField := {
		fieldName := FROM_E,
		addressField := from_addr.addr,
		fromParams := from_addr.params
	},
	p_associated_uri := p_associated_uri,
	require := require,
	security_client := security_client,
	security_server := security_server,
	server := server,
	supported := supported,
	toField := {
		fieldName := TO_E,
		addressField := to_addr.addr,
		toParams := to_addr.params
	},
	userAgent := userAgent,
	via := via,
	wwwAuthenticate := wwwAuthenticate
}


template (value) PDU_SIP_Request
ts_SIP_REGISTER(template (value) SipUrl sip_url_host_port,
		template (value) CallidString call_id,
		template (value) SipAddr from_addr,
		template (value) SipAddr to_addr,
		template (value) Via via,
		integer seq_nr,
		template (omit) Contact contact,
		template (omit) Expires expires,
		template (omit) Authorization authorization := omit,
		template (omit) Require require := omit,
		template (omit) Security_client security_client := omit,
		template (omit) Supported supported := omit,
		template (omit) charstring body := omit) := {
	requestLine := ts_SIP_ReqLine(REGISTER_E, sip_url_host_port),
	msgHeader := ts_SIP_msgh_std(call_id, from_addr, to_addr, contact,
				     "REGISTER", seq_nr, via,
				     content_length := f_ContentLength(body),
				     content_type := f_ContentTypeOrOmit(ts_CT_SDP, body),
				     authorization := authorization,
				     expires := expires,
				     require := require,
				     security_client := security_client,
				     supported := supported),
	messageBody := body,
	payload := omit
}
template (present) PDU_SIP_Request
tr_SIP_REGISTER(template (present) SipUrl sip_url_host_port := ?,
		template (present) CallidString call_id := ?,
		template (present) SipAddr from_addr := ?,
		template (present) SipAddr to_addr := ?,
		template (present) Via via := tr_Via_from(f_tr_HostPort_opt_defport(?)),
		template integer seq_nr := *,
		template Authorization authorization := *,
		template Contact contact := *,
		template Expires expires := *,
		template Require require := *,
		template Security_client security_client := *,
		template Supported supported := *,
		template charstring body := *) := {
	requestLine := tr_SIP_ReqLine(REGISTER_E, sip_url_host_port),
	msgHeader := tr_SIP_msgh_std(call_id, from_addr, to_addr, contact,
				     via, "REGISTER", seq_nr,
				     authorization := authorization,
				     expires := expires,
				     require := require,
				     security_client := security_client,
				     supported := supported),
	messageBody := body,
	payload := omit
}

template (value) PDU_SIP_Request
ts_SIP_INVITE(template (value) CallidString call_id,
	      template (value) SipAddr from_addr,
	      template (value) SipAddr to_addr,
	      template (value) Via via,
	      template (value) Contact contact,
	      integer seq_nr,
	      template (omit) charstring body := omit) := {
	requestLine := ts_SIP_ReqLine(INVITE_E, to_addr.addr.nameAddr.addrSpec),
	msgHeader := ts_SIP_msgh_std(call_id, from_addr, to_addr, contact,
				     "INVITE", seq_nr,
				     via,
				     content_length := f_ContentLength(body),
				     content_type := f_ContentTypeOrOmit(ts_CT_SDP, body)),
	messageBody := body,
	payload := omit
}
template (present) PDU_SIP_Request
tr_SIP_INVITE(template (present) SipUrl uri,
	      template CallidString call_id,
	      template SipAddr from_addr,
	      template SipAddr to_addr,
	      template Via via := tr_Via_from(f_tr_HostPort_opt_defport(?)),
	      template integer seq_nr,
	      template charstring body) := {
	requestLine := tr_SIP_ReqLine(INVITE_E, uri),
	msgHeader := tr_SIP_msgh_std(call_id, from_addr, to_addr, ?,
				     via, "INVITE", seq_nr),
	messageBody := body,
	payload := omit
}

template (value) PDU_SIP_Request
ts_SIP_BYE(CallidString call_id,
	   template (value) SipAddr from_addr,
	   template (value) SipAddr to_addr,
	   template (value) Via via,
	   integer seq_nr,
	   template (omit) charstring body) := {
	requestLine := ts_SIP_ReqLine(BYE_E, to_addr.addr.nameAddr.addrSpec),
	msgHeader := ts_SIP_msgh_std(call_id, from_addr, to_addr, omit, "BYE", seq_nr,
				     via,
				     content_length := f_ContentLength(body),
				     content_type := f_ContentTypeOrOmit(ts_CT_SDP, body)),
	messageBody := body,
	payload := omit
}

template (present) PDU_SIP_Request
tr_SIP_BYE(template (present) SipUrl uri,
	   template CallidString call_id,
	   template SipAddr from_addr,
	   template SipAddr to_addr,
	   template Via via,
	   template integer seq_nr,
	   template charstring body := *) := {
	requestLine := tr_SIP_ReqLine(BYE_E, uri),
	msgHeader := tr_SIP_msgh_std(call_id, from_addr, to_addr, omit,
				     via, "BYE", seq_nr),
	messageBody := body,
	payload := omit
}


template (value) PDU_SIP_Request
ts_SIP_ACK(template (value) CallidString call_id,
	   template (value) SipAddr from_addr,
	   template (value) SipAddr to_addr,
	   template (value) Via via,
	   integer seq_nr,
	   template (omit) charstring body) := {
	requestLine := ts_SIP_ReqLine(ACK_E, to_addr.addr.nameAddr.addrSpec),
	msgHeader := ts_SIP_msgh_std(call_id, from_addr, to_addr,
				     ts_Contact_SipAddr(from_addr),
				     "ACK", seq_nr,
				     via,
				     content_length := f_ContentLength(body),
				     content_type := f_ContentTypeOrOmit(ts_CT_SDP, body)),
	messageBody := body,
	payload := omit
}
template (present) PDU_SIP_Request
tr_SIP_ACK(template (present) SipUrl uri,
	   template CallidString call_id,
	   template SipAddr from_addr,
	   template SipAddr to_addr,
	   template Via via,
	   template integer seq_nr,
	   template charstring body) := {
	requestLine := tr_SIP_ReqLine(ACK_E, uri),
	msgHeader := tr_SIP_msgh_std(call_id, from_addr, to_addr, *,
				     via,
				     "ACK", seq_nr),
	messageBody := body,
	payload := omit
}

template (present) PDU_SIP_Request
tr_SIP_CANCEL(template (present) SipUrl uri,
	      template (present) CallidString call_id,
	      template (present) SipAddr from_addr,
	      template (present) SipAddr to_addr,
	      template (present) Via via,
	      template (present) integer seq_nr,
	      template charstring body := *) := {
	requestLine := tr_SIP_ReqLine(CANCEL_E, uri),
	msgHeader := tr_SIP_msgh_std(call_id, from_addr, to_addr, *,
				     via,
				     "CANCEL", seq_nr),
	messageBody := body,
	payload := omit
}

template (value) PDU_SIP_Response
ts_SIP_Response(template (value) CallidString call_id,
		template (value) SipAddr from_addr,
		template (value) SipAddr to_addr,
		charstring method,
		integer status_code,
		integer seq_nr,
		charstring reason,
		Via via,
		template (omit) Allow allow := omit,
		template (omit) P_Associated_Uri p_associated_uri := omit,
		template (omit) Require require := omit,
		template (omit) Server server := omit,
		template (omit) Supported supported := omit,
		template (omit) UserAgent userAgent := omit,
		template (omit) charstring body := omit) := {
	statusLine := ts_SIP_StatusLine(status_code, reason),
	msgHeader := ts_SIP_msgh_std(call_id, from_addr, to_addr, omit, method, seq_nr,
				     via,
				     content_length := f_ContentLength(body),
				     content_type := f_ContentTypeOrOmit(ts_CT_SDP, body),
				     allow := allow,
				     p_associated_uri := p_associated_uri,
				     require := require,
				     server := server,
				     supported := supported,
				     userAgent := userAgent),
	messageBody := body,
	payload := omit
}
/* 100 Trying */
template (value) PDU_SIP_Response
ts_SIP_Response_Trying(
	template (value) CallidString call_id,
	template (value) SipAddr from_addr,
	template (value) SipAddr to_addr,
	Via via,
	integer seq_nr,
	charstring method := "INVITE",
	template (omit) Allow allow := omit,
	template (omit) Server server := omit,
	template (omit) UserAgent userAgent := omit,
	template (omit) charstring body := omit) := {
	statusLine := ts_SIP_StatusLine(100, "Trying"),
	msgHeader := ts_SIP_msgh_std(call_id, from_addr, to_addr, omit, method, seq_nr,
				     via,
				     content_length := f_ContentLength(body),
				     content_type := f_ContentTypeOrOmit(ts_CT_SDP, body),
				     allow := allow,
				     server := server,
				     userAgent := userAgent),
	messageBody := body,
	payload := omit
}
/* 180 Ringing */
template (value) PDU_SIP_Response
ts_SIP_Response_Ringing(
	template (value) CallidString call_id,
	template (value) SipAddr from_addr,
	template (value) SipAddr to_addr,
	Via via,
	integer seq_nr,
	charstring method := "INVITE",
	template (omit) charstring body := omit) := {
	statusLine := ts_SIP_StatusLine(180, "Ringing"),
	msgHeader := ts_SIP_msgh_std(call_id, from_addr, to_addr, omit, method, seq_nr,
				     via,
				     content_length := f_ContentLength(body),
				     content_type := f_ContentTypeOrOmit(ts_CT_SDP, body)),
	messageBody := body,
	payload := omit
}

/* 401 Unauthorized */
template (value) PDU_SIP_Response
ts_SIP_Response_Unauthorized(
	template (value) CallidString call_id,
	template (value) SipAddr from_addr,
	template (value) SipAddr to_addr,
	Via via,
	template (value) WwwAuthenticate wwwAuthenticate,
	integer seq_nr,
	charstring method := "REGISTER",
	template (omit) Allow allow := omit,
	template (omit) P_Associated_Uri p_associated_uri := omit,
	template (omit) Security_server security_server := omit,
	template (omit) Server server := omit,
	template (omit) Supported supported := omit,
	template (omit) UserAgent userAgent := omit,
	template (omit) charstring body := omit) := {
	statusLine := ts_SIP_StatusLine(401, "Unauthorized"),
	msgHeader := ts_SIP_msgh_std(call_id, from_addr, to_addr, omit, method, seq_nr,
				     via,
				     content_length := f_ContentLength(body),
				     content_type := f_ContentTypeOrOmit(ts_CT_SDP, body),
				     allow := allow,
				     p_associated_uri := p_associated_uri,
				     security_server := security_server,
				     server := server,
				     supported := supported,
				     userAgent := userAgent,
				     wwwAuthenticate := wwwAuthenticate),
	messageBody := body,
	payload := omit
}

template (present) PDU_SIP_Response
tr_SIP_Response(template CallidString call_id,
		template SipAddr from_addr,
		template SipAddr to_addr,
		template (present) Via via := tr_Via_from(?),
		template Contact contact,
		template charstring method,
		template integer status_code,
		template integer seq_nr := ?,
		template charstring reason := ?,
		template charstring body := *) := {
	statusLine := tr_SIP_StatusLine(status_code, reason),
	msgHeader := tr_SIP_msgh_std(call_id, from_addr, to_addr, contact,
				     via,
				     method, seq_nr),
	messageBody := body,
	payload := omit
}

/* Expect during first REGISTER/INVITE/... when authorization is required: */
template (present) PDU_SIP_Response
tr_SIP_Response_Unauthorized(
	template CallidString call_id,
	template SipAddr from_addr,
	template SipAddr to_addr,
	template (present) Via via := tr_Via_from(?),
	template Contact contact := *,
	template (present) WwwAuthenticate wwwAuthenticate := ?,
	template integer seq_nr := ?,
	template charstring method := "REGISTER",
	template integer status_code := 401,
	template charstring reason := "Unauthorized",
	template charstring body := *) := {
	statusLine := tr_SIP_StatusLine(status_code, reason),
	msgHeader := tr_SIP_msgh_std(call_id, from_addr, to_addr, contact,
				     via,
				     method, seq_nr,
				     wwwAuthenticate := wwwAuthenticate),
	messageBody := body,
	payload := omit
}

/* 100 Trying */
template (present) PDU_SIP_Response
tr_SIP_Response_Trying(
	template CallidString call_id,
	template SipAddr from_addr,
	template SipAddr to_addr,
	template (present) Via via := tr_Via_from(?),
	template integer seq_nr := ?,
	template charstring method := "INVITE",
	template integer status_code := 100,
	template charstring reason := "Trying",
	template charstring body := *) := {
	statusLine := tr_SIP_StatusLine(status_code, reason),
	msgHeader := tr_SIP_msgh_std(call_id, from_addr, to_addr, omit,
				     via,
				     method, seq_nr),
	messageBody := body,
	payload := omit
}

/* 180 Ringing */
template (present) PDU_SIP_Response
tr_SIP_Response_Ringing(
	template CallidString call_id,
	template SipAddr from_addr,
	template SipAddr to_addr,
	template (present) Via via := tr_Via_from(?),
	template integer seq_nr := ?,
	template charstring method := "INVITE",
	template integer status_code := 180,
	template charstring reason := "Ringing",
	template charstring body := *) := {
	statusLine := tr_SIP_StatusLine(status_code, reason),
	msgHeader := tr_SIP_msgh_std(call_id, from_addr, to_addr, *,
				     via,
				     method, seq_nr),
	messageBody := body,
	payload := omit
}

/****************
 * FUNCTIONS:
 ****************/

function f_sip_param_find(GenericParam_List li,
			  template (present) charstring id := ?)
return template (omit) GenericParam {
	var integer i;

	for (i := 0; i < lengthof(li); i := i + 1) {
		if (not ispresent(li[i])) {
			continue;
		}
		if (match(li[i].id, id)) {
			return li[i];
		}
	}
	return omit;
}

function f_sip_param_find_or_fail(GenericParam_List li,
				  template (present) charstring id := ?)
return GenericParam {
	var template (omit) GenericParam parameter;
	parameter := f_sip_param_find(li, id);
	if (istemplatekind(parameter, "omit")) {
		Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
			log2str("Param ", id, " not found in ", li));
	}
	return valueof(parameter);
}

function f_sip_param_get_value(GenericParam_List li,
			       template (present) charstring id := ?)
return template (omit) charstring {
	var template (omit) GenericParam parameter;
	parameter := f_sip_param_find(li, id);
	if (istemplatekind(parameter, "omit")) {
		return omit;
	}
	return parameter.paramValue;
}

function f_sip_param_get_value_or_fail(GenericParam_List li,
					       template (present) charstring id := ?)
return template (omit) charstring {
	var GenericParam parameter;
	parameter := f_sip_param_find_or_fail(li, id);
	return parameter.paramValue;
}

function f_sip_param_get_value_present_or_fail(GenericParam_List li,
				       template (present) charstring id := ?)
return charstring {
	var GenericParam parameter;
	parameter := f_sip_param_find_or_fail(li, id);
	if (not ispresent(parameter.paramValue)) {
		Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
					log2str("Param ", id, " value not present in ", li));
	}
	return parameter.paramValue;
}

function f_sip_param_match_value(GenericParam_List li,
				 template (present) charstring id := ?,
				 template charstring exp_paramValue := *)
return boolean {
	var template (omit) charstring val;
	val := f_sip_param_get_value_or_fail(li, id);
	if (istemplatekind(val, "omit")) {
		return istemplatekind(val, "omit") or istemplatekind(val, "*");
	}
	return match(valueof(val), exp_paramValue);
}

function f_sip_param_match_value_or_fail(GenericParam_List li,
					 template (present) charstring id := ?,
					 template charstring exp_paramValue := *)
{
	var template (omit) charstring val := f_sip_param_get_value_or_fail(li, id);
	if (istemplatekind(val, "omit")) {
		if (istemplatekind(val, "omit") or istemplatekind(val, "*")) {
			return;
		} else {
			Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
						log2str("Param ", id, " match failed: val ", val,
							" vs exp ", exp_paramValue));
		}
	}
	if (not match(valueof(val), exp_paramValue)) {
		Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
					log2str("Param ", id, " match failed: val ", val,
						" vs exp ", exp_paramValue));
	}
}

function f_sip_param_remove(template (omit) GenericParam_List li_tpl, charstring id)
return GenericParam_List {
	var integer i;
	var GenericParam_List li;
	var GenericParam_List new_li := {};

	if (istemplatekind(li_tpl, "omit")) {
		return {};
	}

	li := valueof(li_tpl);
	for (i := 0; i < lengthof(li); i := i + 1) {
		if (not ispresent(li[i]) or
		    not match(li[i].id, id)) {
			new_li := new_li & {li[i]};
		}
	}
	return new_li;
}

function f_sip_param_set(template (omit) GenericParam_List li_tpl, charstring id, charstring val)
return GenericParam_List {
	var integer i;
	var GenericParam_List li;
	var GenericParam_List new_li := {};
	var boolean found := false;

	if (istemplatekind(li_tpl, "omit")) {
		return { valueof(ts_Param(id, val)) };
	}

	li := valueof(li_tpl);
	for (i := 0; i < lengthof(li); i := i + 1) {
		if (not ispresent(li[i]) or
		    not match(li[i].id, id)) {
			new_li := new_li & {li[i]};
			continue;
		}
		new_li := new_li & { valueof(ts_Param(li[i].id, val)) };
		found := true;
	}

	if (not found) {
		new_li := new_li & { valueof(ts_Param(id, val)) };
	}
	return new_li;
}

/* Make sure string is quoted. */
function f_sip_str_quote(template (value) charstring val) return charstring {
	var charstring str := valueof(val);
	if (lengthof(str) == 0) {
		return "";
	}

	if (str[0] != "\"") {
		return "\"" & str & "\"";
	}
	return str;
}

/* Make sure string is unquoted.
 * Similar to unq() in RFC 2617 */
function f_sip_str_unquote(template (value) charstring val) return charstring {
	var charstring str := valueof(val);
	var integer len := lengthof(str);

	if (len <= 1) {
		return str;
	}

	if (str[0] == "\"" and str[len - 1] == "\"") {
		return substr(str, 1, len - 2);
	}
	return str;
}

/* RFC 2617 3.2.2.2 A1 */
function f_sip_digest_A1(charstring user, charstring realm, charstring password) return charstring {

	/* RFC 2617 3.2.2.2 A1 */
	var charstring A1 := f_sip_str_unquote(user) & ":" &
			     f_sip_str_unquote(realm) & ":" &
			     password;
	var charstring digestA1 := f_str_tolower(f_calculateMD5(A1));
	log("A1: md5('", A1, "') = ", digestA1);
	return digestA1;
}

/* RFC 2617 3.2.2.2 A2 */
function f_sip_digest_A2(charstring method, charstring uri) return charstring {

	var charstring A2 := method & ":" & uri
	var charstring digestA2 := f_str_tolower(f_calculateMD5(A2));
	log("A2: md5('", A2, "') = ", digestA2);
	return digestA2;
}

/* RFC 2617 3.2.2.1 Request-Digest */
function f_sip_digest_RequestDigest(charstring digestA1, charstring nonce,
				    charstring nc, charstring cnonce,
				    charstring qop, charstring digestA2) return charstring {
	var charstring digest_data := f_sip_str_unquote(nonce) & ":" &
				      nc & ":" &
				      cnonce & ":" &
				      f_sip_str_unquote(qop) & ":" &
				      digestA2;
	var charstring req_digest := f_sip_digest_KD(digestA1, digest_data);
	log("Request-Digest: md5('", digestA1, ":", digest_data ,"') = ", req_digest);
	return req_digest;
}

/* RFC 2617 3.2.1 The WWW-Authenticate Response Header
 * KD(secret, data) = H(concat(secret, ":", data))
 */
function f_sip_digest_KD(charstring secret, charstring data) return charstring {
	return f_str_tolower(f_calculateMD5(secret & ":" & data));
}

/* Digest Auth: RFC 2617 */
function f_sip_digest_gen_Authorization(WwwAuthenticate www_authenticate,
				 charstring user, charstring password,
				 charstring method, charstring uri,
				 charstring cnonce := "0a4f113b", integer nc_int := 1) return Authorization {
	var CommaParam_List digestCln;
	var template (value) Authorization authorization;
	var template (value) Credentials cred;
	var template (omit) GenericParam rx_param;

	digestCln := www_authenticate.challenge[0].digestCln;

	var charstring algorithm;
	rx_param := f_sip_param_find(digestCln, "algorithm");
	if (istemplatekind(rx_param, "omit")) {
		/* Assume MD5 if not set */
		algorithm := "MD5"
	} else {
		algorithm := valueof(rx_param.paramValue);
		if (f_strstr(algorithm, "MD5") == -1) {
			Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
						log2str("Unexpected algorithm: ", algorithm));
		}
	}

	var charstring realm := f_sip_param_get_value_present_or_fail(digestCln, "realm");
	var charstring nonce := f_sip_param_get_value_present_or_fail(digestCln, "nonce");
	var charstring opaque := f_sip_param_get_value_present_or_fail(digestCln, "opaque");
	var charstring qop := f_sip_param_get_value_present_or_fail(digestCln, "qop");

	if (f_strstr(qop, "auth") == -1) {
		Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail, log2str("Unexpected qop: ", qop));
	}
	var charstring selected_qop := "auth";

	/* RFC 2617 3.2.2.2 A1 */
	var charstring digestA1 := f_sip_digest_A1(user, realm, password);
	/* RFC 2617 3.2.2.3 A2 */
	var charstring digestA2 := f_sip_digest_A2(method, uri);

	/* RFC 2617 3.2.2.1 Request-Digest */
	var charstring nc := f_str_tolower(hex2str(int2hex(nc_int, 8)));
	var charstring req_digest := f_sip_digest_RequestDigest(digestA1, nonce,
								nc, cnonce,
								selected_qop, digestA2);

	cred := ts_Credentials_DigestResponseMD5(user, realm, nonce,
						 uri, req_digest,
						 opaque, algorithm, selected_qop, cnonce, nc);

	authorization := ts_Authorization(cred);
	return valueof(authorization);
}

/* RFC 2617 3.5 Example */
function f_sip_digest_selftest() {
/*
The following example assumes that an access-protected document is
being requested from the server via a GET request. The URI of the
document is "http://www.nowhere.org/dir/index.html". Both client and
server know that the username for this document is "Mufasa", and the
password is "Circle Of Life" (with one space between each of the
three words).

HTTP/1.1 401 Unauthorized
WWW-Authenticate: Digest
	realm="testrealm@host.com",
	qop="auth,auth-int",
	nonce="dcd98b7102dd2f0e8b11d0f600bfb0c093",
	opaque="5ccc069c403ebaf9f0171e9517f40e41"

Authorization: Digest username="Mufasa",
	realm="testrealm@host.com",
	nonce="dcd98b7102dd2f0e8b11d0f600bfb0c093",
	uri="/dir/index.html",
	qop=auth,
	nc=00000001,
	cnonce="0a4f113b",
	response="6629fae49393a05397450978507c4ef1",
	opaque="5ccc069c403ebaf9f0171e9517f40e41"
*/
	var template (value) CommaParam_List digestCln := {
		ts_Param("realm", f_sip_str_quote("testrealm@host.com")),
		ts_Param("qop", f_sip_str_quote("auth,auth-int")),
		ts_Param("nonce", f_sip_str_quote("dcd98b7102dd2f0e8b11d0f600bfb0c093")),
		ts_Param("opaque", f_sip_str_quote("5ccc069c403ebaf9f0171e9517f40e41"))
	};
	var template (value) WwwAuthenticate www_authenticate :=
		ts_WwwAuthenticate( { ts_Challenge_digestCln(digestCln) } )

	var Authorization authorization :=
		f_sip_digest_gen_Authorization(valueof(www_authenticate),
					       "Mufasa",
					       "Circle Of Life",
					       "GET",
					       "/dir/index.html",
					       cnonce := "0a4f113b",
					       nc_int := 1);

	var CommaParam_List digestResp := authorization.body.digestResponse;
	f_sip_param_match_value_or_fail(digestResp, "realm",	f_sip_str_quote("testrealm@host.com"));
	f_sip_param_match_value_or_fail(digestResp, "nonce",	f_sip_str_quote("dcd98b7102dd2f0e8b11d0f600bfb0c093"));
	f_sip_param_match_value_or_fail(digestResp, "uri",	f_sip_str_quote("/dir/index.html"));
	f_sip_param_match_value_or_fail(digestResp, "qop",	"auth");
	f_sip_param_match_value_or_fail(digestResp, "nc",	"00000001");
	f_sip_param_match_value_or_fail(digestResp, "cnonce",	f_sip_str_quote("0a4f113b"));
	f_sip_param_match_value_or_fail(digestResp, "response",	f_sip_str_quote("6629fae49393a05397450978507c4ef1"));
	f_sip_param_match_value_or_fail(digestResp, "opaque",	f_sip_str_quote("5ccc069c403ebaf9f0171e9517f40e41"));
}

/* RFC 3261 8.1.1.5:
 * "The sequence number value MUST be expressible as a 32-bit unsigned integer
 *  and MUST be less than 2**31."
 */
function f_sip_rand_seq_nr() return integer {
	 /* 2**31 = 2147483648 */
	return f_rnd_int(2147483648)
}

function f_sip_next_seq_nr(integer seq_nr) return integer {
	return (seq_nr + 1) mod 2147483648;
}

function f_sip_Request_inc_seq_nr(inout template (value) PDU_SIP_Request req) {
	req.msgHeader.cSeq.seqNumber := f_sip_next_seq_nr(valueof(req.msgHeader.cSeq.seqNumber));
}

function f_sip_rand_tag() return charstring {
	/* Tags shall have at least 32 bit of randomness */
	var integer rnd_int := f_rnd_int(4294967296);
	/* Make collisions harder by appending time to the final string: */
	var integer ts_int := f_time_ms() mod 4294967296;
	return hex2str(int2hex(rnd_int, 8)) & "-" & hex2str(int2hex(ts_int, 8));
}

/* Generate a "branch" tag value.
 * RFC 3261 p.105 section 8:
 * "A common way to create this value is to compute a
 * cryptographic hash of the To tag, From tag, Call-ID header
 * field, the Request-URI of the request received (before
 * translation), the topmost Via header, and the sequence number
 * from the CSeq header field, in addition to any Proxy-Require
 * and Proxy-Authorization header fields that may be present.  The
 * algorithm used to compute the hash is implementation-dependent,
 * but MD5 (RFC 1321 [35]),expressed in hexadecimal, is a reasonable
 * choice."
 * See also Section 8.1.1.7:
 * "The branch ID inserted by an element compliant with this
 * specification MUST always begin with the characters "z9hG4bK"."
 */
const charstring sip_magic_cookie := "z9hG4bK";
function f_sip_gen_branch(charstring tag_to,
			  charstring tag_from,
			  charstring tag_call_id,
			  integer cseq) return charstring {
	var charstring str := tag_to & tag_from & tag_call_id & int2str(cseq);
	var charstring hash := f_calculateMD5(str);
	var charstring branch := sip_magic_cookie & hash;
	return branch;
}

function f_sip_HostPort_to_str(HostPort host_port) return charstring {
	var charstring str := "";
	if (ispresent(host_port.host)) {
		str := host_port.host;
	}
	if (ispresent(host_port.portField)) {
		str := str & ":" & int2str(host_port.portField);
	}
	return str;
}

function f_sip_SipUrl_to_str(SipUrl uri) return charstring {
	var charstring str := uri.scheme & ":";
	if (ispresent(uri.userInfo)) {
		str := str & uri.userInfo.userOrTelephoneSubscriber & "@";
	}
	str := str & f_sip_HostPort_to_str(uri.hostPort);
	return str;
}

function f_sip_NameAddr_to_str(NameAddr naddr) return charstring {
	if (ispresent(naddr.displayName)) {
		return naddr.displayName & " <" & f_sip_SipUrl_to_str(naddr.addrSpec) & ">";
	} else {
		return f_sip_SipUrl_to_str(naddr.addrSpec);
	}
}

function f_sip_SipAddr_to_str(SipAddr sip_addr) return charstring {
	if (ischosen(sip_addr.addr.nameAddr)) {
		return f_sip_NameAddr_to_str(sip_addr.addr.nameAddr);
	} else {
		return f_sip_SipUrl_to_str(sip_addr.addr.addrSpecUnion);
	}
}

}