@@ -842,7 +842,7 @@ if(is_rfc1918("$rd")) {

 	<section id="nathelper.set_contact_alias">

 		<title>

-		<function moreinfo="none">set_contact_alias()</function>

+		<function moreinfo="none">set_contact_alias([trim])</function>

 		</title>

 		<para>

 		Adds an <quote>;alias=ip~port~transport</quote> parameter to the

@@ -850,6 +850,16 @@ if(is_rfc1918("$rd")) {

 		The new contact URI is immediately visible to other modules in the

 		way the <function>fix_nated_contact()</function> does it.

 		</para>

+		<para>Meaning of parameters:</para>

+		<itemizedlist>

+			<listitem>

+				<para>

+					<emphasis>trim</emphasis> - by default, set_contact_alias() will not detect and trim an

+					already existing alias parameter. If this optional parameter is set to "1", set_contact_alias()

+					will trim the existing alias before adding a new one.

+				</para>

+			</listitem>

+		</itemizedlist>

 		<para>

 		This function can be used from

 		REQUEST_ROUTE, ONREPLY_ROUTE, BRANCH_ROUTE, and FAILURE_ROUTE.

@@ -110,6 +110,7 @@ static int fix_nated_contact_f(struct sip_msg *, char *, char *);

 static int add_contact_alias_0_f(struct sip_msg *, char *, char *);

 static int add_contact_alias_3_f(struct sip_msg *, char *, char *, char *);

 static int set_contact_alias_f(struct sip_msg *msg, char *str1, char *str2);

+static int w_set_contact_alias_f(struct sip_msg *msg, char *str1, char *str2);

 static int handle_ruri_alias_f(struct sip_msg *, char *, char *);

 static int pv_get_rr_count_f(struct sip_msg *, pv_param_t *, pv_value_t *);

 static int pv_get_rr_top_count_f(struct sip_msg *, pv_param_t *, pv_value_t *);

@@ -212,6 +213,8 @@ static cmd_export_t cmds[] = {

 	{"set_contact_alias",  (cmd_function)set_contact_alias_f,  0,

 		0, 0,

 		REQUEST_ROUTE|ONREPLY_ROUTE|BRANCH_ROUTE|LOCAL_ROUTE},

+	{"set_contact_alias",  (cmd_function)w_set_contact_alias_f, 1,

+		fixup_int_1, 0, REQUEST_ROUTE|ONREPLY_ROUTE|BRANCH_ROUTE|LOCAL_ROUTE},

 	{"handle_ruri_alias",  (cmd_function)handle_ruri_alias_f,    0,

 		0, 0,

 		REQUEST_ROUTE|BRANCH_ROUTE|LOCAL_ROUTE},

@@ -704,10 +707,12 @@ static int fix_nated_contact_f(struct sip_msg *msg, char *str1, char *str2)

  * Replaces ip:port pair in the Contact: field with the source address

  * of the packet.

  */

-static int set_contact_alias(struct sip_msg *msg)

+static int set_contact_alias(struct sip_msg *msg, int trim)

 {

 	char nbuf[MAX_URI_SIZE];

+	char cbuf[MAX_URI_SIZE];

 	str nuri;

+	str curi;

 	int br;

 	int offset, len;

@@ -718,16 +723,24 @@ static int set_contact_alias(struct sip_msg *msg)

 	nuri.s = nbuf;

 	nuri.len = MAX_URI_SIZE;

+	curi.s = cbuf;

+	curi.len = MAX_URI_SIZE;

 	if(get_contact_uri(msg, &uri, &c) == -1)

 		return -1;

 	if((c->uri.s < msg->buf) || (c->uri.s > (msg->buf + msg->len))) {

 		LM_ERR("you can't update contact twice, check your config!\n");

 		return -1;

 	}

-

-	if(uri_add_rcv_alias(msg, &c->uri, &nuri) < 0) {

-		LM_DBG("cannot add the alias parameter\n");

-		return -1;

+	if(trim > 0 && uri_trim_rcv_alias(&c->uri, &curi) > 0) {

+		if(uri_add_rcv_alias(msg, &curi, &nuri) < 0) {

+			LM_DBG("cannot add the alias parameter\n");

+			return -1;

+		}

+	} else {

+		if(uri_add_rcv_alias(msg, &c->uri, &nuri) < 0) {

+			LM_DBG("cannot add the alias parameter\n");

+			return -1;

+		}

 	}

 	br = 1;

@@ -767,9 +780,31 @@ static int set_contact_alias(struct sip_msg *msg)

 	return 1;

 }

+static int ki_set_contact_alias(struct sip_msg *msg)

+{

+	return set_contact_alias(msg, 0);

+}

+

+static int ki_set_contact_alias_trim(struct sip_msg *msg)

+{

+	return set_contact_alias(msg, 1);

+}

+

 static int set_contact_alias_f(struct sip_msg *msg, char *str1, char *str2)

 {

-	return set_contact_alias(msg);

+	return set_contact_alias(msg, 0);

+}

+

+static int w_set_contact_alias_f(struct sip_msg *msg, char *str1, char *str2)

+{

+	int i = 0;

+	if(str1) {

+		if(get_int_fparam(&i, msg, (fparam_t *)str1) < 0)

+			return -1;

+	}

+	if(i > 1)

+		i = 1;

+	return set_contact_alias(msg, i);

 }

 #define SALIAS ";alias="

@@ -2689,7 +2724,12 @@ static sr_kemi_t sr_kemi_nathelper_exports[] = {

 			SR_KEMIP_NONE, SR_KEMIP_NONE, SR_KEMIP_NONE }

 	},

 	{ str_init("nathelper"), str_init("set_contact_alias"),

-		SR_KEMIP_INT, set_contact_alias,

+		SR_KEMIP_INT, ki_set_contact_alias,

+		{ SR_KEMIP_NONE, SR_KEMIP_NONE, SR_KEMIP_NONE,

+			SR_KEMIP_NONE, SR_KEMIP_NONE, SR_KEMIP_NONE }

+	},

+	{ str_init("nathelper"), str_init("set_contact_alias_trim"),

+		SR_KEMIP_INT, ki_set_contact_alias_trim,

 		{ SR_KEMIP_NONE, SR_KEMIP_NONE, SR_KEMIP_NONE,

 			SR_KEMIP_NONE, SR_KEMIP_NONE, SR_KEMIP_NONE }

 	},