modules_k/pv: Add s.sql transformation to turn PV into suitable SQL value.

This transformation outputs valid SQL values for various PV values:
 - <null> values are output as NULL
 - integers are output as integers
 - everything else is output as quoted and escaped string

Example:
	$var(null) = $null;
	$avp(null) = $null;
	$avp(str) = "String with \ illegal \\characters";
	$avp(nr) = 12345;
	$avp(strnr) = "12345";

	xlog("$$rm = $rm = $(rm{s.sql})");
	xlog("$$var(null) = $var(null) = $(var(null){s.sql})");
	xlog("$$avp(null) = $avp(null) = $(avp(null){s.sql})");
	xlog("$$avp(str) = $avp(str) = $(avp(str){s.sql})");
	xlog("$$avp(nr) = $avp(nr) = $(avp(nr){s.sql})");
	xlog("$$avp(strnr) = $avp(strnr) = $(avp(strnr){s.sql})");

Output:
$rm = ACK = 'ACK'
$var(null) = 0 = 0
$avp(null) = <null> = NULL
$avp(str) = String with \ illegal \characters = 'String with \\ illegal \\characters'
$avp(nr) = 12345 = 12345
$avp(strnr) = 12345 = '12345'

modules_k/pv/pv_trans.c

@@ -54,6 +54,7 @@
 
 /*! transformation buffer */
 static char _tr_buffer[TR_BUFFER_SIZE];
+static str _tr_null = { "NULL", 4 };
 
 
 /*!
@@ -73,7 +74,7 @@ int tr_eval_string(struct sip_msg *msg, tr_param_t *tp, int subtype,
 	pv_value_t v, w;
 	void *vp;
 
-	if(val==NULL || val->flags&PV_VAL_NULL)
+	if(val==NULL || (val->flags&PV_VAL_NULL && subtype != TR_S_SQL))
 		return -1;
 
 	switch(subtype)
@@ -593,6 +594,31 @@ int tr_eval_string(struct sip_msg *msg, tr_param_t *tp, int subtype,
 			val->rs.s = _tr_buffer;
 			break;
 
+		case TR_S_SQL:
+			if (val->flags&PV_VAL_NULL) {
+				val->flags = PV_VAL_STR;
+				val->rs = _tr_null;
+				break;
+			}
+			if(val->flags&PV_TYPE_INT || !(val->flags&PV_VAL_STR)) {
+				val->rs.s = int2str(val->ri, &val->rs.len);
+				val->flags = PV_VAL_STR;
+				break;
+			}
+			if(val->rs.len>TR_BUFFER_SIZE/2-1) {
+				LM_ERR("escape buffer to short");
+				return -1;
+			}
+			_tr_buffer[0] = '\'';
+			i = escape_common(_tr_buffer+1, val->rs.s, val->rs.len);
+			_tr_buffer[++i] = '\'';
+			_tr_buffer[++i] = '\0';
+			memset(val, 0, sizeof(pv_value_t));
+			val->flags = PV_VAL_STR;
+			val->rs.s = _tr_buffer;
+			val->rs.len = i;
+			break;
+
 		default:
 			LM_ERR("unknown subtype %d\n",
 					subtype);
@@ -1353,6 +1379,9 @@ char* tr_parse_string(str* in, trans_t *t)
 	} else if(name.len==3 && strncasecmp(name.s, "md5", 3)==0) {
 		t->subtype = TR_S_MD5;
 		goto done;
+	} else if(name.len==3 && strncasecmp(name.s, "sql", 3)==0) {
+		t->subtype = TR_S_SQL;
+		goto done;
 	} else if(name.len==7 && strncasecmp(name.s, "tolower", 7)==0) {
 		t->subtype = TR_S_TOLOWER;
 		goto done;

modules_k/pv/pv_trans.h

@@ -40,7 +40,7 @@ enum _tr_s_subtype {
 	TR_S_ESCAPECOMMON, TR_S_UNESCAPECOMMON, TR_S_ESCAPEUSER, TR_S_UNESCAPEUSER,
 	TR_S_ESCAPEPARAM, TR_S_UNESCAPEPARAM, TR_S_TOLOWER, TR_S_TOUPPER,
 	TR_S_STRIP, TR_S_STRIPTAIL, TR_S_PREFIXES, TR_S_PREFIXES_QUOT, TR_S_REPLACE,
-	TR_S_TIMEFORMAT
+	TR_S_TIMEFORMAT, TR_S_SQL
 };
 enum _tr_uri_subtype {
 	TR_URI_NONE=0, TR_URI_USER, TR_URI_HOST, TR_URI_PASSWD, TR_URI_PORT,