How to define a dynamic string data type in postgres extension?

I am trying to define a custom data type in postgreSQL that takes two arguments: a long long int (int8 in postgres) and a dynamic string (varchar or TEXT in postgres). I am able to get the long long int working but I am having troubles to implement the dynamic string. This is what I have in my c code for the in and out functions:

In function:

 Datum object3d_in(PG_FUNCTION_ARGS) {
    char* str = PG_GETARG_CSTRING(0);
    long long int timeStamp;
    char *temp;
    Object3d *result;

    if (sscanf(str, "(%lli, %s)", &timeStamp, temp) != 2)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                        errmsg("Invalid input syntax for object3d: \"%s\"",
                                str)));

    result = (Object3d *) palloc(sizeof(Object3d));
    result->timeStamp = timeStamp;

    result->object = (char*) palloc(sizeof(char)*(strlen(temp) + 1));
    sscanf(str, "(%lli, %s)", &timeStamp, result->object); //Reload
    PG_RETURN_POINTER(result);
}

Out function:

Datum object3d_out(PG_FUNCTION_ARGS) {
    Object3d *object3d = (Object3d *) PG_GETARG_POINTER(0);
    char *result;
    result = (char *) palloc(128);
    snprintf(result, 128, "[%lli, %s]", object3d->timeStamp, object3d->object);
    PG_RETURN_CSTRING(result);
}

postgres type commands:

CREATE TYPE object3d;

CREATE FUNCTION object3d_in(cstring)
RETURNS object3d
AS 'mdobject.dll'
LANGUAGE C IMMUTABLE STRICT;

CREATE FUNCTION object3d_out(object3d)
RETURNS cstring
AS 'mdobject.dll'
LANGUAGE C IMMUTABLE STRICT; 

CREATE TYPE object3d(
    INTERNALLENGTH = 128, 
    input = object3d_in,
    output = object3d_out
);

CREATE TABLE listobject3d (id integer, theobject object3d);
INSERT INTO listobject3d VALUES (random()*100, '(203,12 )'); 
INSERT INTO listobject3d VALUES (random()*100, '(20120202,r )');
INSERT INTO listobject3d VALUES (random()*100, '(20120203,c )');
INSERT INTO listobject3d VALUES (random()*100, '(20120203,triangle )');

Output:

SELECT * FROM listobject3d;

 id |     theobject
----+-------------------
 21 | [203, 12]
 42 | [20120202, /\x01]
 19 | [20120203, /\x01]
 33 | [20120203,     ]
(4 rows)