SQL: Sending data through a URL

Problem

I was trying to send JSON data through a URL and it was trickier than I thought.
I was getting "bad URL" returned from the receiving sever because there were characters in the data which were interfering with the rest of the JSON record that I was trying to post. I needed to strip these out.

I tried a few things that I thought looked promising including UTL_URL.escape.
I also went through tons of forums and the below function ALMOST made the cut, but it couldn't handle large fields.

with trans_tbl(ch_frm, str_to) as (
     select '"',     '\"' from dual union
     select '/',     '\/' from dual union
     select '\',     '\\' from dual union
     select chr(8),  '\b' from dual union -- BS
     select chr(12), '\f' from dual union -- FF
     select chr(10), '\n' from dual union -- NL
     select chr(13), '\r' from dual union -- CR
     select chr(9),  '\t' from dual       -- HT
   ),
   inp_str(txt) as (
     select string_in from dual
   )
   select SUBSTR(max(replace(sys_connect_by_path(ch,'`'),'`')),1,32000) as c_text
   into s_converted   
   from (
   select lvl
    ,decode(str_to,null,substr(txt, lvl, 1),str_to) as ch
    from inp_str cross join (select level lvl from inp_str connect by level <= length(txt))
    left outer join trans_tbl on (ch_frm = substr(txt, lvl, 1))
    )
    connect by lvl = prior lvl+1
    start with lvl = 1;

Solution

I settled on this where b.question_text is a clob
regexp_replace(REGEXP_REPLACE(ASCIISTR(substr(replace(b.question_text,'"',''),1,3500)), '\\[[:xdigit:]]{4}', ''),'<.*?>')

The data was coming from a MSSQL database so "asciistr" ensures that we don't have any strange characters
It works in conjunction with  '\\[[:xdigit:]]{4}' to strip out the literals returns by asciistr.
Finally, another egexp_replace, this time with "<.*?>", which trips out all of the HTML tags in my data.
 The 3500 character limit was necessary in my case, but I'm not sure if this was just a restriction on my receiving server.

Acknowledgment

http://psoug.org/definition/ASCIISTR.htm
http://stackoverflow.com/questions/2236475/finding-and-removing-non-ascii-characters-from-an-oracle-varchar2