CID 498025 and CID 498031: Overflowed constant INTEGER_OVERFLOW

Undetected overflow could lead to an infinite loop on ISC_R_NOSPACE being returned. In practice this will only happen if we have a coding error as no rdataset is big enough to overflow a 2G buffer but we should add an INSIST to detect this.

181        while (!done) {
182                isc_buffer_allocate(mctx, &b, size);
183                result = dns_rdata_totext(rdata, NULL, b);
184                if (result == ISC_R_SUCCESS) {
185                        printf("%.*s\n", (int)isc_buffer_usedlength(b),
186                               (char *)isc_buffer_base(b));
187                        done = true;
188                } else if (result != ISC_R_NOSPACE) {
189                        check_result(result, "dns_rdata_totext");
190                }
191                isc_buffer_free(&b);
     	
CID 498025: (#1 of 1): Overflowed constant (INTEGER_OVERFLOW)
overflow_const: Expression size, which is equal to 0, overflows the type that receives it, an unsigned integer 32 bits wide.
192                size *= 2;
193        }

181retry:
182        isc_buffer_allocate(mctx, &b, bufsize);
183        result = dns_rdata_totext(rdata, NULL, b);
184        if (result == ISC_R_NOSPACE) {
185                isc_buffer_free(&b);
     	
CID 498031: (#1 of 1): Overflowed constant (INTEGER_OVERFLOW)
overflow_const: Expression bufsize, which is equal to 0, overflows the type that receives it, an unsigned integer 32 bits wide.
186                bufsize *= 2;
187                goto retry;
188        }