pv: added strip and striptail transformations

- s.strip and s.striptail transformations to remove prefix or suffix
  from pseudo-variables
- straightforward option instead of more complex format of s.substr for
  these two common operations in sip routing

modules_k/pv/pv_trans.c

@@ -415,6 +415,42 @@ int tr_eval_string(struct sip_msg *msg, tr_param_t *tp, int subtype,
 			val->rs = st;
 			break;
 
+		case TR_S_STRIP:
+		case TR_S_STRIPTAIL:
+			if(tp==NULL)
+			{
+				LM_ERR("strip invalid parameters\n");
+				return -1;
+			}
+			if(!(val->flags&PV_VAL_STR))
+				val->rs.s = int2str(val->ri, &val->rs.len);
+			if(tp->type==TR_PARAM_NUMBER)
+			{
+				i = tp->v.n;
+			} else {
+				if(pv_get_spec_value(msg, (pv_spec_p)tp->v.data, &v)!=0
+						|| (!(v.flags&PV_VAL_INT)))
+				{
+					LM_ERR("select cannot get p1\n");
+					return -1;
+				}
+				i = v.ri;
+			}
+			val->flags = PV_VAL_STR;
+			val->ri = 0;
+			if(i<=0)
+				break;
+			if(i>=val->rs.len)
+			{
+				val->rs.s = "";
+				val->rs.len = 0;
+				break;
+			}
+			if(subtype==TR_S_STRIP)
+				val->rs.s += i;
+			val->rs.len -= i;
+			break;
+
 		default:
 			LM_ERR("unknown subtype %d\n",
 					subtype);
@@ -1277,6 +1313,46 @@ char* tr_parse_string(str* in, trans_t *t)
 			goto error;
 		}
 		goto done;
+	} else if(name.len==5 && strncasecmp(name.s, "strip", 5)==0) {
+		t->subtype = TR_S_STRIP;
+		if(*p!=TR_PARAM_MARKER)
+		{
+			LM_ERR("invalid strip transformation: %.*s!\n",
+					in->len, in->s);
+			goto error;
+		}
+		p++;
+		_tr_parse_nparam(p, p0, tp, spec, n, sign, in, s);
+		t->params = tp;
+		tp = 0;
+		while(*p && (*p==' ' || *p=='\t' || *p=='\n')) p++;
+		if(*p!=TR_RBRACKET)
+		{
+			LM_ERR("invalid strip transformation: %.*s!!\n",
+				in->len, in->s);
+			goto error;
+		}
+		goto done;
+	} else if(name.len==9 && strncasecmp(name.s, "striptail", 9)==0) {
+		t->subtype = TR_S_STRIPTAIL;
+		if(*p!=TR_PARAM_MARKER)
+		{
+			LM_ERR("invalid striptail transformation: %.*s!\n",
+					in->len, in->s);
+			goto error;
+		}
+		p++;
+		_tr_parse_nparam(p, p0, tp, spec, n, sign, in, s);
+		t->params = tp;
+		tp = 0;
+		while(*p && (*p==' ' || *p=='\t' || *p=='\n')) p++;
+		if(*p!=TR_RBRACKET)
+		{
+			LM_ERR("invalid striptail transformation: %.*s!!\n",
+				in->len, in->s);
+			goto error;
+		}
+		goto done;
 	}
 
 	LM_ERR("unknown transformation: %.*s/%.*s/%d!\n", in->len, in->s,

modules_k/pv/pv_trans.h

@@ -38,7 +38,8 @@ enum _tr_s_subtype {
 	TR_S_NONE=0, TR_S_LEN, TR_S_INT, TR_S_MD5, TR_S_SUBSTR,
 	TR_S_SELECT, TR_S_ENCODEHEXA, TR_S_DECODEHEXA,
 	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_ESCAPEPARAM, TR_S_UNESCAPEPARAM, TR_S_TOLOWER, TR_S_TOUPPER,
+	TR_S_STRIP, TR_S_STRIPTAIL
 };
 enum _tr_uri_subtype {
 	TR_URI_NONE=0, TR_URI_USER, TR_URI_HOST, TR_URI_PASSWD, TR_URI_PORT,