question on ldap_escape_func in rlm_ldap.c (author: Kostas Kalevras)

[Qin Zhen]

Hi All,
I'm new to Radius, now encountered problems with ldap_escape_func in rlm_ldap. please help me since it's really a bit urgent. 


the comments regarding to this function is 'Add an ldap_escape_func. Escape the * character from the filter so that we can avoid the trivial DoS of username=*'. if i was not wrong, this function intends to filter out the * which follows the username, i.e, if username is 'userid*' in access-request packet, ldapsearch is only based on 'userid'. but what's the purpose for doing this and is it secure? or did i misunderstand the comments? 

the lastest version freeradius-1.0.5 has a slightly different version for this piece of code, 
*****************************************************************
freeradius-1.0.5
             if (strchr("*=\\,()", *in)) {
                        static const char *hex = "0123456789abcdef";
                        if (outlen <= 3) break;

                        *(out++) = '\\';
                        *(out++) = hex[((*in) >> 4) & 0x0f];
                        *(out++) = hex[(*in) & 0x0f];
                        outlen -= 3;
                        continue;
                }
**************************************************************
freeradius-1.0.4 and previous 

                if (strchr("*", *in)) {
                        in++;
                        outlen--;
                        continue;
                }

i couldn't figure out what does the change intend to do, is it to filter out '*', '\\', '()' and '=' from username? and why should it be in that way? please help me. thanks a lot in advance. 

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