Question

The code below is suppose to print out the TXT Resource Records i have in my zone file.
When i execute the code only with BLOCK 1 (BLOCK 2 not present) i get the name, Type, Class,TTL and Data Length for each of the 3 TXT RRs i have.
But when i execute the code only with BLOCK 2, i only get the answer for the first TXT RR and then an error message: ns_parserr: Message to long.
Can somebody plese help me with this problem.
Thanks in advance.

    int rrnum;  /* resource record number */
    ns_rr rr;   /* expanded resource record */
    for(rrnum = 0; rrnum < ns_msg_count(handle, ns_s_an); rrnum++)
    {
    //from section ns_s_an(ANSWER) take out answer number rrnum and put it in rr        
    if (ns_parserr(&handle, ns_s_an, rrnum, &rr)) {
        fprintf(stderr, "ns_parserr: %s\n", strerror(errno));
    }
    if (ns_rr_type(rr)==ns_t_txt){  
        //BLOCK 1
                    char *cp;
        cp=(char *)ns_rr_name(rr);
        printf("CP->%s\n",(char *)cp);
        int i1=ns_rr_type(rr);
        printf("Type->%d\n", i1);
        int i2=ns_rr_class(rr);
        printf("Class->%d\n", i2);      
        int i3=ns_rr_ttl(rr);
        printf("TTL->%d\n", i3);
        int i4=ns_rr_rdlen(rr);
        printf("Data Length->%d\n\n", i4);

                    //BLOCK 2
        u_char const *rdata=ns_rr_rdata(rr);
        printf("Data->%s\n",(u_char *)rdata);
        char *rdatatemp;
        rdatatemp=(char *)rdata;
        int len=strlen(rdata);
        printf("%d\n",len);
        rdatatemp[strlen(rdata)-2]='\0';
        printf("Data->%s\n",(u_char *)rdatatemp);   
    }
}

This is the result i get with the two blocks on:
vanco@vanco-laptop:~/Desktop$ gcc d2ip.c /usr/lib/libresolv.a
vanco@vanco-laptop:~/Desktop$ ./a.out http://www.example.com
CP->http://www.example.com
Type->16
Class->1
TTL->10800
Data Length->41

Data->(ver=dgw1 pre=8 id=0 name=www.example.com�

43
Data->(ver=dgw1 pre=8 id=0 name=www.example.com
ns_parserr: Message too long

Answer 1

You’re modifying the memory pointed to by the u_char const * returned by ns_rr_rdata(rr); via circumventing the const using a cast

u_char const *rdata=ns_rr_rdata(rr);
...
char *rdatatemp;
rdatatemp=(char *)rdata;
...
rdatatemp[strlen(rdata)-2]='\0';

You need to allocate a new char array and copy from rdata